Grand test fixup (#138)

* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig

.drone.yml

@@ -1,13 +1,37 @@
+---
+### Drone configuration file for GoToSocial.
+### Connects to https://drone.superseriousbusiness.org to perform testing, linting, and automatic builds/pushes to docker.
+###
+### For documentation on drone, see: https://docs.drone.io/
+### For documentation on drone docker pipelines in particular: https://docs.drone.io/pipeline/docker/overview/
+
 kind: pipeline
 type: docker
-name: dockerpublish
+name: default
 steps:
-  - name: publish image
+
+# We use golangci-lint for linting.
+# See: https://golangci-lint.run/
+- name: lint
+  image: golangci/golangci-lint:v1.41.1
+  commands:
+  - golangci-lint run --timeout 5m0s --tests=false --verbose
+
+- name: test
+  image: golang:1.16.4
+  environment:
+    GTS_DB_ADDRESS: postgres
+  commands:
+  # `-count 1`  => run all tests at least once
+  # `-p 1`      => run maximum one test at a time
+  # `./...`     => run all tests
+  - go test -count 1 -p 1 ./...
+
+- name: publish
   image: plugins/docker
   settings:
     auto_tag: true
-      username:
+    username: gotosocial
-        from_secret: gts_docker_username
     password:
       from_secret: gts_docker_password
     repo: superseriousbusiness/gotosocial
@@ -16,3 +40,16 @@ steps:
     event:
       exclude:
         - pull_request
+
+services:
+# We need this postgres service running for the test step.
+# See: https://docs.drone.io/pipeline/docker/syntax/services/
+- name: postgres
+  image: postgres
+  environment:
+    POSTGRES_PASSWORD: postgres
+---
+kind: signature
+hmac: 78dd20d97444a9e2904552d56eb52f43ad30ba27e1d897a5ea6808971f9a0ae2
+
+...

.github/workflows/golangci-lint.yml

@@ -1,37 +0,0 @@
-name: golangci-lint
-on:
-  push:
-    tags:
-      - v*
-    branches:
-      - main
-  pull_request:
-jobs:
-  golangci:
-    name: lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: golangci-lint
-        uses: golangci/golangci-lint-action@v2
-        with:
-          # Optional: version of golangci-lint to use in form of v1.2 or v1.2.3 or `latest` to use the latest version
-          version: v1.29
-
-          # Optional: working directory, useful for monorepos
-          # working-directory: somedir
-
-          # Optional: golangci-lint command line arguments.
-          # args: --issues-exit-code=0
-
-          # Optional: show only new issues if it's a pull request. The default value is `false`.
-          # only-new-issues: true
-
-          # Optional: if set to true then the action will use pre-installed Go.
-          # skip-go-installation: true
-
-          # Optional: if set to true then the action don't cache or restore ~/go/pkg.
-          # skip-pkg-cache: true
-
-          # Optional: if set to true then the action don't cache or restore ~/.cache/go-build.
-          # skip-build-cache: true

CONTRIBUTING.md

@@ -10,9 +10,7 @@ Check the [issues](https://github.com/superseriousbusiness/gotosocial/issues) to
 
 ## Communications
 
-Before starting on something, please comment on an issue to say that you're working on it, and send a message to `@dumpsterqueer@ondergrond.org` (Mastodon) to let them know.
+Before starting on something, please comment on an issue to say that you're working on it, and/or drop into the GoToSocial Matrix room [here](https://matrix.to/#/#gotosocial:superseriousbusiness.org).
-
-You can also drop into the GoToSocial Matrix room [here](https://matrix.to/#/!mdShFtfScQvVSmjIKX:ondergrond.org?via=ondergrond.org).
 
 This is the recommended way of keeping in touch with other developers, asking direct questions about code, and letting everyone know what you're up to.
 
@@ -36,6 +34,38 @@ If there are no errors, great, you're good to go!
 
 To work with the stylesheet for templates, you need [Node.js](https://nodejs.org/en/download/), then run `yarn install` in `web/source/`. Recompiling the bundle.css is `node build.js` but can be automated with [nodemon](https://www.npmjs.com/package/nodemon) on file change: `nodemon -w style.css build.js`.
 
+### Golang forking quirks
+
+One of the quirks of Golang is that it relies on the source management path being the same as the one used within `go.mod` and in package imports within individual Go files. This makes working with forks a bit awkward.
+
+Let's say you fork GoToSocial to `github.com/yourgithubname/gotosocial`, and then clone that repository to `~/go/src/github.com/yourgithubname/gotosocial`. You will probably run into errors trying to run tests or build, so you might change your `go.mod` file so that the module is called `github.com/yourgithubname/gotosocial` instead of `github.com/superseriousbusiness/gotosocial`. But then this breaks all the imports within the project. Nightmare! So now you have to go through the source files and painstakingly replace `github.com/superseriousbusiness/gotosocial` with `github.com/yourgithubname/gotosocial`. This works OK, but when you decide to make a pull request against the original repo, all the changed paths are included! Argh!
+
+The correct solution to this is to fork, then clone the upstream repository, then set `origin` of the upstream repository to that of your fork.
+
+See [this blogpost](https://blog.sgmansfield.com/2016/06/working-with-forks-in-go/) for more details.
+
+In case this post disappears, here are the steps (slightly modified):
+
+>
+> Pull the original package from the canonical place with the standard go get command:
+> 
+> `go get github.com/superseriousbusiness/gotosocial`
+> 
+> Fork the repository on Github or set up whatever other remote git repo you will be using. In this case, I would go to Github and fork the repository.
+> 
+> Navigate to the top level of the repository on your computer. Note that this might not be the specific package you’re using:
+> 
+> `cd $GOPATH/src/github.com/superseriousbusiness/gotosocial`
+> 
+> Rename the current origin remote to upstream:
+> 
+> `git remote rename origin upstream`
+> 
+> Add your fork as origin:
+> 
+> `git remote add origin git@github.com/yourgithubname/gotosocial`
+>
+
 ## Setting up your test environment
 
 GoToSocial provides a [testrig](https://github.com/superseriousbusiness/gotosocial/tree/main/testrig) with a bunch of mock packages you can use in integration tests.

Dockerfile

@@ -12,8 +12,11 @@ ADD cmd /go/src/github.com/superseriousbusiness/gotosocial/cmd
 ADD internal /go/src/github.com/superseriousbusiness/gotosocial/internal
 ADD testrig /go/src/github.com/superseriousbusiness/gotosocial/testrig
 ADD docs/swagger.go /go/src/github.com/superseriousbusiness/gotosocial/docs/swagger.go
+
+# dependencies and vendor
 ADD go.mod /go/src/github.com/superseriousbusiness/gotosocial/go.mod
 ADD go.sum /go/src/github.com/superseriousbusiness/gotosocial/go.sum
+ADD vendor /go/src/github.com/superseriousbusiness/gotosocial/vendor
 
 # move .git dir and version for versioning
 ADD .git /go/src/github.com/superseriousbusiness/gotosocial/.git

README.md

@@ -107,6 +107,10 @@ Proper documentation for running and maintaining GoToSocial will be forthcoming
 
 For now (if you want to run it pre-alpha, like a beast), check out the [quick and dirty getting started guide](https://docs.gotosocial.org/en/latest/installation_guide/quick_and_dirty/).
 
+## Contributing
+
+You wanna contribute to GtS? Great! ❤️❤️❤️ Check out the issues page to see if there's anything you wanna jump in on, and read the [CONTRIBUTING.md](./CONTRIBUTING.md) file for guidelines and setting up your dev environment.
+
 ## Contact
 
 For questions and comments, you can [join our Matrix channel](https://matrix.to/#/#gotosocial:superseriousbusiness.org) at `#gotosocial:superseriousbusiness.org`. This is the quickest way to reach the devs. You can also mail [admin@gotosocial.org](mailto:admin@gotosocial.org).

internal/api/client/media/mediacreate_test.go

@@ -156,7 +156,7 @@ func (suite *MediaCreateTestSuite) TestStatusCreatePOSTImageHandlerSuccessful()
 	}
 
 	// check response
-	suite.EqualValues(http.StatusAccepted, recorder.Code)
+	suite.EqualValues(http.StatusOK, recorder.Code)
 
 	result := recorder.Result()
 	defer result.Body.Close()

internal/api/client/status/statuscreate_test.go

@@ -96,7 +96,7 @@ func (suite *StatusCreateTestSuite) TestPostNewStatus() {
 		"status":       {"this is a brand new status! #helloworld"},
 		"spoiler_text": {"hello hello"},
 		"sensitive":    {"true"},
-		"visibility_advanced": {"mutuals_only"},
+		"visibility":   {string(model.VisibilityMutualsOnly)},
 		"likeable":     {"false"},
 		"replyable":    {"false"},
 		"federated":    {"false"},
@@ -120,7 +120,7 @@ func (suite *StatusCreateTestSuite) TestPostNewStatus() {
 	assert.Equal(suite.T(), "hello hello", statusReply.SpoilerText)
 	assert.Equal(suite.T(), "<p>this is a brand new status! <a href=\"http://localhost:8080/tags/helloworld\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\">#<span>helloworld</span></a></p>", statusReply.Content)
 	assert.True(suite.T(), statusReply.Sensitive)
-	assert.Equal(suite.T(), model.VisibilityPrivate, statusReply.Visibility)
+	assert.Equal(suite.T(), model.VisibilityPrivate, statusReply.Visibility) // even though we set this status to mutuals only, it should serialize to private, because masto has no idea about mutuals_only
 	assert.Len(suite.T(), statusReply.Tags, 1)
 	assert.Equal(suite.T(), model.Tag{
 		Name: "helloworld",
@@ -161,13 +161,11 @@ func (suite *StatusCreateTestSuite) TestPostAnotherNewStatus() {
 	b, err := ioutil.ReadAll(result.Body)
 	assert.NoError(suite.T(), err)
 
-	fmt.Println(string(b))
-
 	statusReply := &model.Status{}
 	err = json.Unmarshal(b, statusReply)
 	assert.NoError(suite.T(), err)
 
-	assert.Equal(suite.T(), "<p><a href=\"http://localhost:8080/tags/test\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\">#<span>test</span></a> alright, should be able to post <a href=\"http://localhost:8080/tags/links\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\">#<span>links</span></a> with fragments in them now, let&#39;s see........<br/><br/><a href=\"https://docs.gotosocial.org/en/latest/user_guide/posts/#links\" rel=\"noopener nofollow noreferrer\" target=\"_blank\">docs.gotosocial.org/en/latest/user_guide/posts/#links</a><br/><a href=\"http://localhost:8080/tags/gotosocial\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\">#<span>gotosocial</span></a><br/><br/>(tobi remember to pull the docker image challenge)</p>", statusReply.Content)
+	assert.Equal(suite.T(), "\u003cp\u003e\u003ca href=\"http://localhost:8080/tags/test\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\"\u003e#\u003cspan\u003etest\u003c/span\u003e\u003c/a\u003e alright, should be able to post \u003ca href=\"http://localhost:8080/tags/links\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\"\u003e#\u003cspan\u003elinks\u003c/span\u003e\u003c/a\u003e with fragments in them now, let\u0026#39;s see........\u003cbr/\u003e\u003cbr/\u003e\u003ca href=\"https://docs.gotosocial.org/en/latest/user_guide/posts/#links\" rel=\"noopener nofollow noreferrer\" target=\"_blank\"\u003edocs.gotosocial.org/en/latest/user_guide/posts/#links\u003c/a\u003e\u003cbr/\u003e\u003cbr/\u003e\u003ca href=\"http://localhost:8080/tags/gotosocial\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\"\u003e#\u003cspan\u003egotosocial\u003c/span\u003e\u003c/a\u003e\u003cbr/\u003e\u003cbr/\u003e(tobi remember to pull the docker image challenge)\u003c/p\u003e", statusReply.Content)
 }
 
 func (suite *StatusCreateTestSuite) TestPostNewStatusWithEmoji() {

internal/federation/federator_test.go

@@ -19,18 +19,13 @@
 package federation_test
 
 import (
-	"bytes"
 	"context"
-	"crypto/x509"
-	"encoding/pem"
-	"fmt"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
-	"strings"
 	"testing"
 
 	"github.com/go-fed/activity/pub"
+	"github.com/go-fed/httpsig"
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/suite"
@@ -117,63 +112,31 @@ func (suite *ProtocolTestSuite) TestAuthenticatePostInbox() {
 	sendingAccount := suite.accounts["remote_account_1"]
 	inboxAccount := suite.accounts["local_account_1"]
 
-	encodedPublicKey, err := x509.MarshalPKIXPublicKey(sendingAccount.PublicKey)
+	tc := testrig.NewTestTransportController(testrig.NewMockHTTPClient(nil), suite.db)
-	assert.NoError(suite.T(), err)
-	publicKeyBytes := pem.EncodeToMemory(&pem.Block{
-		Type:  "PUBLIC KEY",
-		Bytes: encodedPublicKey,
-	})
-	publicKeyString := strings.ReplaceAll(string(publicKeyBytes), "\n", "\\n")
-
-	// for this test we need the client to return the public key of the activity creator on the 'remote' instance
-	responseBodyString := fmt.Sprintf(`
-	{
-		"@context": [
-			"https://www.w3.org/ns/activitystreams",
-			"https://w3id.org/security/v1"
-		],
-
-		"id": "%s",
-		"type": "Person",
-		"preferredUsername": "%s",
-		"inbox": "%s",
-
-		"publicKey": {
-			"id": "%s",
-			"owner": "%s",
-			"publicKeyPem": "%s"
-		}
-	}`, sendingAccount.URI, sendingAccount.Username, sendingAccount.InboxURI, sendingAccount.PublicKeyURI, sendingAccount.URI, publicKeyString)
-
-	// create a transport controller whose client will just return the response body string we specified above
-	tc := testrig.NewTestTransportController(testrig.NewMockHTTPClient(func(req *http.Request) (*http.Response, error) {
-		r := ioutil.NopCloser(bytes.NewReader([]byte(responseBodyString)))
-		return &http.Response{
-			StatusCode: 200,
-			Body:       r,
-		}, nil
-	}), suite.db)
-
 	// now setup module being tested, with the mock transport controller
 	federator := federation.NewFederator(suite.db, testrig.NewTestFederatingDB(suite.db), tc, suite.config, suite.log, suite.typeConverter, testrig.NewTestMediaHandler(suite.db, suite.storage))
 
-	// setup request
+	request := httptest.NewRequest(http.MethodPost, "http://localhost:8080/users/the_mighty_zork/inbox", nil)
+	// we need these headers for the request to be validated
+	request.Header.Set("Signature", activity.SignatureHeader)
+	request.Header.Set("Date", activity.DateHeader)
+	request.Header.Set("Digest", activity.DigestHeader)
+
+	verifier, err := httpsig.NewVerifier(request)
+	assert.NoError(suite.T(), err)
+
 	ctx := context.Background()
 	// by the time AuthenticatePostInbox is called, PostInboxRequestBodyHook should have already been called,
 	// which should have set the account and username onto the request. We can replicate that behavior here:
 	ctxWithAccount := context.WithValue(ctx, util.APAccount, inboxAccount)
 	ctxWithActivity := context.WithValue(ctxWithAccount, util.APActivity, activity)
+	ctxWithVerifier := context.WithValue(ctxWithActivity, util.APRequestingPublicKeyVerifier, verifier)
 
-	request := httptest.NewRequest(http.MethodPost, "http://localhost:8080/users/the_mighty_zork/inbox", nil) // the endpoint we're hitting
-	// we need these headers for the request to be validated
-	request.Header.Set("Signature", activity.SignatureHeader)
-	request.Header.Set("Date", activity.DateHeader)
-	request.Header.Set("Digest", activity.DigestHeader)
 	// we can pass this recorder as a writer and read it back after
 	recorder := httptest.NewRecorder()
 
 	// trigger the function being tested, and return the new context it creates
-	newContext, authed, err := federator.AuthenticatePostInbox(ctxWithActivity, recorder, request)
+	newContext, authed, err := federator.AuthenticatePostInbox(ctxWithVerifier, recorder, request)
 	assert.NoError(suite.T(), err)
 	assert.True(suite.T(), authed)
 

internal/oauth/clientstore_test.go

@@ -21,12 +21,10 @@ import (
 	"context"
 	"testing"
 
-	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/suite"
-	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
-	"github.com/superseriousbusiness/gotosocial/internal/db/pg"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/testrig"
 	"github.com/superseriousbusiness/oauth2/v4/models"
 )
 
@@ -43,7 +41,7 @@ const ()
 
 // SetupSuite sets some variables on the suite that we can use as consts (more or less) throughout
 func (suite *PgClientStoreTestSuite) SetupSuite() {
-	suite.testClientID = "test-client-id"
+	suite.testClientID = "01FCVB74EW6YBYAEY7QG9CQQF6"
 	suite.testClientSecret = "test-client-secret"
 	suite.testClientDomain = "https://example.org"
 	suite.testClientUserID = "test-client-user-id"
@@ -51,50 +49,13 @@ func (suite *PgClientStoreTestSuite) SetupSuite() {
 
 // SetupTest creates a postgres connection and creates the oauth_clients table before each test
 func (suite *PgClientStoreTestSuite) SetupTest() {
-	log := logrus.New()
+	suite.db = testrig.NewTestDB()
-	log.SetLevel(logrus.TraceLevel)
+	testrig.StandardDBSetup(suite.db, nil)
-	c := config.Empty()
-	c.DBConfig = &config.DBConfig{
-		Type:            "postgres",
-		Address:         "localhost",
-		Port:            5432,
-		User:            "postgres",
-		Password:        "postgres",
-		Database:        "postgres",
-		ApplicationName: "gotosocial",
-	}
-	db, err := pg.NewPostgresService(context.Background(), c, log)
-	if err != nil {
-		logrus.Panicf("error creating database connection: %s", err)
-	}
-
-	suite.db = db
-
-	models := []interface{}{
-		&oauth.Client{},
-	}
-
-	for _, m := range models {
-		if err := suite.db.CreateTable(m); err != nil {
-			logrus.Panicf("db connection error: %s", err)
-		}
-	}
 }
 
 // TearDownTest drops the oauth_clients table and closes the pg connection after each test
 func (suite *PgClientStoreTestSuite) TearDownTest() {
-	models := []interface{}{
+	testrig.StandardDBTeardown(suite.db)
-		&oauth.Client{},
-	}
-	for _, m := range models {
-		if err := suite.db.DropTable(m); err != nil {
-			logrus.Panicf("error dropping table: %s", err)
-		}
-	}
-	if err := suite.db.Stop(context.Background()); err != nil {
-		logrus.Panicf("error closing db connection: %s", err)
-	}
-	suite.db = nil
 }
 
 func (suite *PgClientStoreTestSuite) TestClientStoreSetAndGet() {

internal/typeutils/astointernal_test.go

@@ -25,7 +25,6 @@ import (
 	"testing"
 
 	"github.com/go-fed/activity/streams"
-	"github.com/go-fed/activity/streams/vocab"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/suite"
 	"github.com/superseriousbusiness/gotosocial/internal/ap"
@@ -375,62 +374,6 @@ func (suite *ASToInternalTestSuite) TestParseGargron() {
 	// TODO: write assertions here, rn we're just eyeballing the output
 }
 
-func (suite *ASToInternalTestSuite) TestParseStatus() {
-	m := make(map[string]interface{})
-	err := json.Unmarshal([]byte(statusWithEmojisAndTagsAsActivityJson), &m)
-	assert.NoError(suite.T(), err)
-
-	t, err := streams.ToType(context.Background(), m)
-	assert.NoError(suite.T(), err)
-
-	create, ok := t.(vocab.ActivityStreamsCreate)
-	assert.True(suite.T(), ok)
-
-	obj := create.GetActivityStreamsObject()
-	assert.NotNil(suite.T(), obj)
-
-	first := obj.Begin()
-	assert.NotNil(suite.T(), first)
-
-	rep, ok := first.GetType().(ap.Statusable)
-	assert.True(suite.T(), ok)
-
-	status, err := suite.typeconverter.ASStatusToStatus(rep)
-	assert.NoError(suite.T(), err)
-
-	assert.Len(suite.T(), status.GTSEmojis, 3)
-	// assert.Len(suite.T(), status.GTSTags, 2) TODO: implement this first so that it can pick up tags
-}
-
-func (suite *ASToInternalTestSuite) TestParseStatusWithMention() {
-	m := make(map[string]interface{})
-	err := json.Unmarshal([]byte(statusWithMentionsActivityJson), &m)
-	assert.NoError(suite.T(), err)
-
-	t, err := streams.ToType(context.Background(), m)
-	assert.NoError(suite.T(), err)
-
-	create, ok := t.(vocab.ActivityStreamsCreate)
-	assert.True(suite.T(), ok)
-
-	obj := create.GetActivityStreamsObject()
-	assert.NotNil(suite.T(), obj)
-
-	first := obj.Begin()
-	assert.NotNil(suite.T(), first)
-
-	rep, ok := first.GetType().(ap.Statusable)
-	assert.True(suite.T(), ok)
-
-	status, err := suite.typeconverter.ASStatusToStatus(rep)
-	assert.NoError(suite.T(), err)
-
-	fmt.Printf("%+v", status)
-
-	assert.Len(suite.T(), status.GTSMentions, 1)
-	fmt.Println(status.GTSMentions[0])
-}
-
 func (suite *ASToInternalTestSuite) TearDownTest() {
 	testrig.StandardDBTeardown(suite.db)
 }

internal/typeutils/frontendtointernal.go

@@ -32,6 +32,8 @@ func (c *converter) MastoVisToVis(m model.Visibility) gtsmodel.Visibility {
 		return gtsmodel.VisibilityUnlocked
 	case model.VisibilityPrivate:
 		return gtsmodel.VisibilityFollowersOnly
+	case model.VisibilityMutualsOnly:
+		return gtsmodel.VisibilityMutualsOnly
 	case model.VisibilityDirect:
 		return gtsmodel.VisibilityDirect
 	}

testrig/db.go

@@ -20,6 +20,7 @@ package testrig
 
 import (
 	"context"
+	"os"
 
 	"github.com/sirupsen/logrus"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
@@ -52,9 +53,17 @@ var testModels []interface{} = []interface{}{
 	&oauth.Client{},
 }
 
-// NewTestDB returns a new initialized, empty database for testing
+// NewTestDB returns a new initialized, empty database for testing.
+//
+// If the environment variable GTS_DB_ADDRESS is set, it will take that
+// value as the database address instead.
 func NewTestDB() db.DB {
 	config := NewTestConfig()
+	alternateAddress := os.Getenv("GTS_DB_ADDRESS")
+	if alternateAddress != "" {
+		config.DBConfig.Address = alternateAddress
+	}
+
 	l := logrus.New()
 	l.SetLevel(logrus.TraceLevel)
 	testDB, err := pg.NewPostgresService(context.Background(), config, l)

vendor/github.com/aymerick/douceur/LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Aymerick JEHANNE
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

vendor/github.com/aymerick/douceur/css/declaration.go

@@ -0,0 +1,60 @@
+package css
+
+import "fmt"
+
+// Declaration represents a parsed style property
+type Declaration struct {
+	Property  string
+	Value     string
+	Important bool
+}
+
+// NewDeclaration instanciates a new Declaration
+func NewDeclaration() *Declaration {
+	return &Declaration{}
+}
+
+// Returns string representation of the Declaration
+func (decl *Declaration) String() string {
+	return decl.StringWithImportant(true)
+}
+
+// StringWithImportant returns string representation with optional !important part
+func (decl *Declaration) StringWithImportant(option bool) string {
+	result := fmt.Sprintf("%s: %s", decl.Property, decl.Value)
+
+	if option && decl.Important {
+		result += " !important"
+	}
+
+	result += ";"
+
+	return result
+}
+
+// Equal returns true if both Declarations are equals
+func (decl *Declaration) Equal(other *Declaration) bool {
+	return (decl.Property == other.Property) && (decl.Value == other.Value) && (decl.Important == other.Important)
+}
+
+//
+// DeclarationsByProperty
+//
+
+// DeclarationsByProperty represents sortable style declarations
+type DeclarationsByProperty []*Declaration
+
+// Implements sort.Interface
+func (declarations DeclarationsByProperty) Len() int {
+	return len(declarations)
+}
+
+// Implements sort.Interface
+func (declarations DeclarationsByProperty) Swap(i, j int) {
+	declarations[i], declarations[j] = declarations[j], declarations[i]
+}
+
+// Implements sort.Interface
+func (declarations DeclarationsByProperty) Less(i, j int) bool {
+	return declarations[i].Property < declarations[j].Property
+}

vendor/github.com/aymerick/douceur/css/rule.go

@@ -0,0 +1,230 @@
+package css
+
+import (
+	"fmt"
+	"strings"
+)
+
+const (
+	indentSpace = 2
+)
+
+// RuleKind represents a Rule kind
+type RuleKind int
+
+// Rule kinds
+const (
+	QualifiedRule RuleKind = iota
+	AtRule
+)
+
+// At Rules than have Rules inside their block instead of Declarations
+var atRulesWithRulesBlock = []string{
+	"@document", "@font-feature-values", "@keyframes", "@media", "@supports",
+}
+
+// Rule represents a parsed CSS rule
+type Rule struct {
+	Kind RuleKind
+
+	// At Rule name (eg: "@media")
+	Name string
+
+	// Raw prelude
+	Prelude string
+
+	// Qualified Rule selectors parsed from prelude
+	Selectors []string
+
+	// Style properties
+	Declarations []*Declaration
+
+	// At Rule embedded rules
+	Rules []*Rule
+
+	// Current rule embedding level
+	EmbedLevel int
+}
+
+// NewRule instanciates a new Rule
+func NewRule(kind RuleKind) *Rule {
+	return &Rule{
+		Kind: kind,
+	}
+}
+
+// Returns string representation of rule kind
+func (kind RuleKind) String() string {
+	switch kind {
+	case QualifiedRule:
+		return "Qualified Rule"
+	case AtRule:
+		return "At Rule"
+	default:
+		return "WAT"
+	}
+}
+
+// EmbedsRules returns true if this rule embeds another rules
+func (rule *Rule) EmbedsRules() bool {
+	if rule.Kind == AtRule {
+		for _, atRuleName := range atRulesWithRulesBlock {
+			if rule.Name == atRuleName {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+// Equal returns true if both rules are equals
+func (rule *Rule) Equal(other *Rule) bool {
+	if (rule.Kind != other.Kind) ||
+		(rule.Prelude != other.Prelude) ||
+		(rule.Name != other.Name) {
+		return false
+	}
+
+	if (len(rule.Selectors) != len(other.Selectors)) ||
+		(len(rule.Declarations) != len(other.Declarations)) ||
+		(len(rule.Rules) != len(other.Rules)) {
+		return false
+	}
+
+	for i, sel := range rule.Selectors {
+		if sel != other.Selectors[i] {
+			return false
+		}
+	}
+
+	for i, decl := range rule.Declarations {
+		if !decl.Equal(other.Declarations[i]) {
+			return false
+		}
+	}
+
+	for i, rule := range rule.Rules {
+		if !rule.Equal(other.Rules[i]) {
+			return false
+		}
+	}
+
+	return true
+}
+
+// Diff returns a string representation of rules differences
+func (rule *Rule) Diff(other *Rule) []string {
+	result := []string{}
+
+	if rule.Kind != other.Kind {
+		result = append(result, fmt.Sprintf("Kind: %s | %s", rule.Kind.String(), other.Kind.String()))
+	}
+
+	if rule.Prelude != other.Prelude {
+		result = append(result, fmt.Sprintf("Prelude: \"%s\" | \"%s\"", rule.Prelude, other.Prelude))
+	}
+
+	if rule.Name != other.Name {
+		result = append(result, fmt.Sprintf("Name: \"%s\" | \"%s\"", rule.Name, other.Name))
+	}
+
+	if len(rule.Selectors) != len(other.Selectors) {
+		result = append(result, fmt.Sprintf("Selectors: %v | %v", strings.Join(rule.Selectors, ", "), strings.Join(other.Selectors, ", ")))
+	} else {
+		for i, sel := range rule.Selectors {
+			if sel != other.Selectors[i] {
+				result = append(result, fmt.Sprintf("Selector: \"%s\" | \"%s\"", sel, other.Selectors[i]))
+			}
+		}
+	}
+
+	if len(rule.Declarations) != len(other.Declarations) {
+		result = append(result, fmt.Sprintf("Declarations Nb: %d | %d", len(rule.Declarations), len(other.Declarations)))
+	} else {
+		for i, decl := range rule.Declarations {
+			if !decl.Equal(other.Declarations[i]) {
+				result = append(result, fmt.Sprintf("Declaration: \"%s\" | \"%s\"", decl.String(), other.Declarations[i].String()))
+			}
+		}
+	}
+
+	if len(rule.Rules) != len(other.Rules) {
+		result = append(result, fmt.Sprintf("Rules Nb: %d | %d", len(rule.Rules), len(other.Rules)))
+	} else {
+
+		for i, rule := range rule.Rules {
+			if !rule.Equal(other.Rules[i]) {
+				result = append(result, fmt.Sprintf("Rule: \"%s\" | \"%s\"", rule.String(), other.Rules[i].String()))
+			}
+		}
+	}
+
+	return result
+}
+
+// Returns the string representation of a rule
+func (rule *Rule) String() string {
+	result := ""
+
+	if rule.Kind == QualifiedRule {
+		for i, sel := range rule.Selectors {
+			if i != 0 {
+				result += ", "
+			}
+			result += sel
+		}
+	} else {
+		// AtRule
+		result += fmt.Sprintf("%s", rule.Name)
+
+		if rule.Prelude != "" {
+			if result != "" {
+				result += " "
+			}
+			result += fmt.Sprintf("%s", rule.Prelude)
+		}
+	}
+
+	if (len(rule.Declarations) == 0) && (len(rule.Rules) == 0) {
+		result += ";"
+	} else {
+		result += " {\n"
+
+		if rule.EmbedsRules() {
+			for _, subRule := range rule.Rules {
+				result += fmt.Sprintf("%s%s\n", rule.indent(), subRule.String())
+			}
+		} else {
+			for _, decl := range rule.Declarations {
+				result += fmt.Sprintf("%s%s\n", rule.indent(), decl.String())
+			}
+		}
+
+		result += fmt.Sprintf("%s}", rule.indentEndBlock())
+	}
+
+	return result
+}
+
+// Returns identation spaces for declarations and rules
+func (rule *Rule) indent() string {
+	result := ""
+
+	for i := 0; i < ((rule.EmbedLevel + 1) * indentSpace); i++ {
+		result += " "
+	}
+
+	return result
+}
+
+// Returns identation spaces for end of block character
+func (rule *Rule) indentEndBlock() string {
+	result := ""
+
+	for i := 0; i < (rule.EmbedLevel * indentSpace); i++ {
+		result += " "
+	}
+
+	return result
+}

vendor/github.com/aymerick/douceur/css/stylesheet.go

@@ -0,0 +1,25 @@
+package css
+
+// Stylesheet represents a parsed stylesheet
+type Stylesheet struct {
+	Rules []*Rule
+}
+
+// NewStylesheet instanciate a new Stylesheet
+func NewStylesheet() *Stylesheet {
+	return &Stylesheet{}
+}
+
+// Returns string representation of the Stylesheet
+func (sheet *Stylesheet) String() string {
+	result := ""
+
+	for _, rule := range sheet.Rules {
+		if result != "" {
+			result += "\n"
+		}
+		result += rule.String()
+	}
+
+	return result
+}

vendor/github.com/aymerick/douceur/parser/parser.go

@@ -0,0 +1,409 @@
+package parser
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/gorilla/css/scanner"
+
+	"github.com/aymerick/douceur/css"
+)
+
+const (
+	importantSuffixRegexp = `(?i)\s*!important\s*$`
+)
+
+var (
+	importantRegexp *regexp.Regexp
+)
+
+// Parser represents a CSS parser
+type Parser struct {
+	scan *scanner.Scanner // Tokenizer
+
+	// Tokens parsed but not consumed yet
+	tokens []*scanner.Token
+
+	// Rule embedding level
+	embedLevel int
+}
+
+func init() {
+	importantRegexp = regexp.MustCompile(importantSuffixRegexp)
+}
+
+// NewParser instanciates a new parser
+func NewParser(txt string) *Parser {
+	return &Parser{
+		scan: scanner.New(txt),
+	}
+}
+
+// Parse parses a whole stylesheet
+func Parse(text string) (*css.Stylesheet, error) {
+	result, err := NewParser(text).ParseStylesheet()
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+// ParseDeclarations parses CSS declarations
+func ParseDeclarations(text string) ([]*css.Declaration, error) {
+	result, err := NewParser(text).ParseDeclarations()
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+// ParseStylesheet parses a stylesheet
+func (parser *Parser) ParseStylesheet() (*css.Stylesheet, error) {
+	result := css.NewStylesheet()
+
+	// Parse BOM
+	if _, err := parser.parseBOM(); err != nil {
+		return result, err
+	}
+
+	// Parse list of rules
+	rules, err := parser.ParseRules()
+	if err != nil {
+		return result, err
+	}
+
+	result.Rules = rules
+
+	return result, nil
+}
+
+// ParseRules parses a list of rules
+func (parser *Parser) ParseRules() ([]*css.Rule, error) {
+	result := []*css.Rule{}
+
+	inBlock := false
+	if parser.tokenChar("{") {
+		// parsing a block of rules
+		inBlock = true
+		parser.embedLevel++
+
+		parser.shiftToken()
+	}
+
+	for parser.tokenParsable() {
+		if parser.tokenIgnorable() {
+			parser.shiftToken()
+		} else if parser.tokenChar("}") {
+			if !inBlock {
+				errMsg := fmt.Sprintf("Unexpected } character: %s", parser.nextToken().String())
+				return result, errors.New(errMsg)
+			}
+
+			parser.shiftToken()
+			parser.embedLevel--
+
+			// finished
+			break
+		} else {
+			rule, err := parser.ParseRule()
+			if err != nil {
+				return result, err
+			}
+
+			rule.EmbedLevel = parser.embedLevel
+			result = append(result, rule)
+		}
+	}
+
+	return result, parser.err()
+}
+
+// ParseRule parses a rule
+func (parser *Parser) ParseRule() (*css.Rule, error) {
+	if parser.tokenAtKeyword() {
+		return parser.parseAtRule()
+	}
+
+	return parser.parseQualifiedRule()
+}
+
+// ParseDeclarations parses a list of declarations
+func (parser *Parser) ParseDeclarations() ([]*css.Declaration, error) {
+	result := []*css.Declaration{}
+
+	if parser.tokenChar("{") {
+		parser.shiftToken()
+	}
+
+	for parser.tokenParsable() {
+		if parser.tokenIgnorable() {
+			parser.shiftToken()
+		} else if parser.tokenChar("}") {
+			// end of block
+			parser.shiftToken()
+			break
+		} else {
+			declaration, err := parser.ParseDeclaration()
+			if err != nil {
+				return result, err
+			}
+
+			result = append(result, declaration)
+		}
+	}
+
+	return result, parser.err()
+}
+
+// ParseDeclaration parses a declaration
+func (parser *Parser) ParseDeclaration() (*css.Declaration, error) {
+	result := css.NewDeclaration()
+	curValue := ""
+
+	for parser.tokenParsable() {
+		if parser.tokenChar(":") {
+			result.Property = strings.TrimSpace(curValue)
+			curValue = ""
+
+			parser.shiftToken()
+		} else if parser.tokenChar(";") || parser.tokenChar("}") {
+			if result.Property == "" {
+				errMsg := fmt.Sprintf("Unexpected ; character: %s", parser.nextToken().String())
+				return result, errors.New(errMsg)
+			}
+
+			if importantRegexp.MatchString(curValue) {
+				result.Important = true
+				curValue = importantRegexp.ReplaceAllString(curValue, "")
+			}
+
+			result.Value = strings.TrimSpace(curValue)
+
+			if parser.tokenChar(";") {
+				parser.shiftToken()
+			}
+
+			// finished
+			break
+		} else {
+			token := parser.shiftToken()
+			curValue += token.Value
+		}
+	}
+
+	// log.Printf("[parsed] Declaration: %s", result.String())
+
+	return result, parser.err()
+}
+
+// Parse an At Rule
+func (parser *Parser) parseAtRule() (*css.Rule, error) {
+	// parse rule name (eg: "@import")
+	token := parser.shiftToken()
+
+	result := css.NewRule(css.AtRule)
+	result.Name = token.Value
+
+	for parser.tokenParsable() {
+		if parser.tokenChar(";") {
+			parser.shiftToken()
+
+			// finished
+			break
+		} else if parser.tokenChar("{") {
+			if result.EmbedsRules() {
+				// parse rules block
+				rules, err := parser.ParseRules()
+				if err != nil {
+					return result, err
+				}
+
+				result.Rules = rules
+			} else {
+				// parse declarations block
+				declarations, err := parser.ParseDeclarations()
+				if err != nil {
+					return result, err
+				}
+
+				result.Declarations = declarations
+			}
+
+			// finished
+			break
+		} else {
+			// parse prelude
+			prelude, err := parser.parsePrelude()
+			if err != nil {
+				return result, err
+			}
+
+			result.Prelude = prelude
+		}
+	}
+
+	// log.Printf("[parsed] Rule: %s", result.String())
+
+	return result, parser.err()
+}
+
+// Parse a Qualified Rule
+func (parser *Parser) parseQualifiedRule() (*css.Rule, error) {
+	result := css.NewRule(css.QualifiedRule)
+
+	for parser.tokenParsable() {
+		if parser.tokenChar("{") {
+			if result.Prelude == "" {
+				errMsg := fmt.Sprintf("Unexpected { character: %s", parser.nextToken().String())
+				return result, errors.New(errMsg)
+			}
+
+			// parse declarations block
+			declarations, err := parser.ParseDeclarations()
+			if err != nil {
+				return result, err
+			}
+
+			result.Declarations = declarations
+
+			// finished
+			break
+		} else {
+			// parse prelude
+			prelude, err := parser.parsePrelude()
+			if err != nil {
+				return result, err
+			}
+
+			result.Prelude = prelude
+		}
+	}
+
+	result.Selectors = strings.Split(result.Prelude, ",")
+	for i, sel := range result.Selectors {
+		result.Selectors[i] = strings.TrimSpace(sel)
+	}
+
+	// log.Printf("[parsed] Rule: %s", result.String())
+
+	return result, parser.err()
+}
+
+// Parse Rule prelude
+func (parser *Parser) parsePrelude() (string, error) {
+	result := ""
+
+	for parser.tokenParsable() && !parser.tokenEndOfPrelude() {
+		token := parser.shiftToken()
+		result += token.Value
+	}
+
+	result = strings.TrimSpace(result)
+
+	// log.Printf("[parsed] prelude: %s", result)
+
+	return result, parser.err()
+}
+
+// Parse BOM
+func (parser *Parser) parseBOM() (bool, error) {
+	if parser.nextToken().Type == scanner.TokenBOM {
+		parser.shiftToken()
+		return true, nil
+	}
+
+	return false, parser.err()
+}
+
+// Returns next token without removing it from tokens buffer
+func (parser *Parser) nextToken() *scanner.Token {
+	if len(parser.tokens) == 0 {
+		// fetch next token
+		nextToken := parser.scan.Next()
+
+		// log.Printf("[token] %s => %v", nextToken.Type.String(), nextToken.Value)
+
+		// queue it
+		parser.tokens = append(parser.tokens, nextToken)
+	}
+
+	return parser.tokens[0]
+}
+
+// Returns next token and remove it from the tokens buffer
+func (parser *Parser) shiftToken() *scanner.Token {
+	var result *scanner.Token
+
+	result, parser.tokens = parser.tokens[0], parser.tokens[1:]
+	return result
+}
+
+// Returns tokenizer error, or nil if no error
+func (parser *Parser) err() error {
+	if parser.tokenError() {
+		token := parser.nextToken()
+		return fmt.Errorf("Tokenizer error: %s", token.String())
+	}
+
+	return nil
+}
+
+// Returns true if next token is Error
+func (parser *Parser) tokenError() bool {
+	return parser.nextToken().Type == scanner.TokenError
+}
+
+// Returns true if next token is EOF
+func (parser *Parser) tokenEOF() bool {
+	return parser.nextToken().Type == scanner.TokenEOF
+}
+
+// Returns true if next token is a whitespace
+func (parser *Parser) tokenWS() bool {
+	return parser.nextToken().Type == scanner.TokenS
+}
+
+// Returns true if next token is a comment
+func (parser *Parser) tokenComment() bool {
+	return parser.nextToken().Type == scanner.TokenComment
+}
+
+// Returns true if next token is a CDO or a CDC
+func (parser *Parser) tokenCDOorCDC() bool {
+	switch parser.nextToken().Type {
+	case scanner.TokenCDO, scanner.TokenCDC:
+		return true
+	default:
+		return false
+	}
+}
+
+// Returns true if next token is ignorable
+func (parser *Parser) tokenIgnorable() bool {
+	return parser.tokenWS() || parser.tokenComment() || parser.tokenCDOorCDC()
+}
+
+// Returns true if next token is parsable
+func (parser *Parser) tokenParsable() bool {
+	return !parser.tokenEOF() && !parser.tokenError()
+}
+
+// Returns true if next token is an At Rule keyword
+func (parser *Parser) tokenAtKeyword() bool {
+	return parser.nextToken().Type == scanner.TokenAtKeyword
+}
+
+// Returns true if next token is given character
+func (parser *Parser) tokenChar(value string) bool {
+	token := parser.nextToken()
+	return (token.Type == scanner.TokenChar) && (token.Value == value)
+}
+
+// Returns true if next token marks the end of a prelude
+func (parser *Parser) tokenEndOfPrelude() bool {
+	return parser.tokenChar(";") || parser.tokenChar("{")
+}

vendor/github.com/buckket/go-blurhash/.gitignore

@@ -0,0 +1,2 @@
+.idea
+coverage.txt

vendor/github.com/buckket/go-blurhash/.travis.yml

@@ -0,0 +1,14 @@
+language: go
+
+go:
+  - 1.13.x
+  - 1.14.x
+
+install:
+  - go get -t -v ./...
+
+script:
+  - go test -race -coverprofile=coverage.txt -covermode=atomic ./...
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)

vendor/github.com/buckket/go-blurhash/LICENSE

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
+freedoms that you received.  You must make sure that they, too, receive
+or can get the source code.  And you must show them these terms so they
+know their rights.
+
+  Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.
+
+  For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.
+
+  Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
+can do so.  This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software.  The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products.  If such problems arise substantially in other domains, we
+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.
+
+  Finally, every program is threatened constantly by software patents.
+States should not allow patents to restrict development and use of
+software on general-purpose computers, but in those that do, we wish to
+avoid the special danger that patents applied to a free program could
+make it effectively proprietary.  To prevent this, the GPL assures that
+patents cannot be used to render the program non-free.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
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+  "This License" refers to version 3 of the GNU General Public License.
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+  "Copyright" also means copyright-like laws that apply to other kinds of
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+  2. Basic Permissions.
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+  All rights granted under this License are granted for the term of
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+
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+similar laws prohibiting or restricting circumvention of such
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+  4. Conveying Verbatim Copies.
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+  You may convey verbatim copies of the Program's source code as you
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+  You may convey a covered work in object code form under the terms
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+    copy of the Corresponding Source for all the software in the
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+  A "User Product" is either (1) a "consumer product", which means any
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+  If you convey an object code work under this section in, or with, or
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+  Corresponding Source conveyed, and Installation Information provided,
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+unpacking, reading or copying.
+
+  7. Additional Terms.
+
+  "Additional permissions" are terms that supplement the terms of this
+License by making exceptions from one or more of its conditions.
+Additional permissions that are applicable to the entire Program shall
+be treated as though they were included in this License, to the extent
+that they are valid under applicable law.  If additional permissions
+apply only to part of the Program, that part may be used separately
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+this License without regard to the additional permissions.
+
+  When you convey a copy of a covered work, you may at your option
+remove any additional permissions from that copy, or from any part of
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+that material) supplement the terms of this License with terms:
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+    terms of sections 15 and 16 of this License; or
+
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+  All other non-permissive additional terms are considered "further
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+  Additional terms, permissive or non-permissive, may be stated in the
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+  8. Termination.
+
+  You may not propagate or modify a covered work except as expressly
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+this License (including any patent licenses granted under the third
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+
+  However, if you cease all violation of this License, then your
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+  Termination of your rights under this section does not terminate the
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+
+  9. Acceptance Not Required for Having Copies.
+
+  You are not required to accept this License in order to receive or
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+occurring solely as a consequence of using peer-to-peer transmission
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+
+  10. Automatic Licensing of Downstream Recipients.
+
+  Each time you convey a covered work, the recipient automatically
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+  An "entity transaction" is a transaction transferring control of an
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+any patent claim is infringed by making, using, selling, offering for
+sale, or importing the Program or any portion of it.
+
+  11. Patents.
+
+  A "contributor" is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's "contributor version".
+
+  A contributor's "essential patent claims" are all patent claims
+owned or controlled by the contributor, whether already acquired or
+hereafter acquired, that would be infringed by some manner, permitted
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+
+  Each contributor grants you a non-exclusive, worldwide, royalty-free
+patent license under the contributor's essential patent claims, to
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+
+  In the following three paragraphs, a "patent license" is any express
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+  If you convey a covered work, knowingly relying on a patent license,
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+
+  If, pursuant to or in connection with a single transaction or
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+
+  A patent license is "discriminatory" if it does not include within
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+conditioned on the non-exercise of one or more of the rights that are
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+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
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+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
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+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
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+option of following the terms and conditions either of that numbered
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+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
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+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
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+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
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+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

vendor/github.com/buckket/go-blurhash/README.md

@@ -0,0 +1,96 @@
+# go-blurhash [![Build Status](https://travis-ci.org/buckket/go-blurhash.svg)](https://travis-ci.org/buckket/go-blurhash) [![Go Report Card](https://goreportcard.com/badge/github.com/buckket/go-blurhash)](https://goreportcard.com/report/github.com/buckket/go-blurhash) [![codecov](https://codecov.io/gh/buckket/go-blurhash/branch/master/graph/badge.svg)](https://codecov.io/gh/buckket/go-blurhash) [![GoDoc](https://godoc.org/github.com/buckket/go-blurhash?status.svg)](https://pkg.go.dev/github.com/buckket/go-blurhash)
+
+**go-blurhash** is a pure Go implementation of the [BlurHash](https://github.com/woltapp/blurhash) algorithm, which is used by
+[Mastodon](https://github.com/tootsuite/mastodon) an other Fediverse software to implement a swift way of preloading placeholder images as well
+as hiding sensitive media. Read more about it [here](https://blog.joinmastodon.org/2019/05/improving-support-for-adult-content-on-mastodon/).
+
+**tl;dr:** BlurHash is a compact representation of a placeholder for an image.
+
+This library allows generating the BlurHash of a given image, as well as
+reconstructing a blurred version with specified dimensions from a given BlurHash.
+
+This library is based on the following reference implementations:
+- Encoder: [https://github.com/woltapp/blurhash/blob/master/C](https://github.com/woltapp/blurhash/blob/master/C) (C)
+- Deocder: [https://github.com/woltapp/blurhash/blob/master/TypeScript](https://github.com/woltapp/blurhash/blob/master/TypeScript) (TypeScript)
+
+BlurHash is written by [Dag Ågren](https://github.com/DagAgren) / [Wolt](https://github.com/woltapp).
+
+|            | Before                         | After                          |
+| ---------- |:------------------------------:| :-----------------------------:|
+| **Image**  | ![alt text][test]              | "LFE.@D9F01_2%L%MIVD*9Goe-;WB" |
+| **Hash**   | "LFE.@D9F01_2%L%MIVD*9Goe-;WB" | ![alt text][test_blur]
+
+[test]: test.png "Blurhash example input."
+[test_blur]: test_blur.png "Blurhash example output"
+
+## Installation
+
+### From source
+
+    go get -u github.com/buckket/go-blurhash
+
+## Usage
+
+go-blurhash exports three functions:
+```go
+func blurhash.Encode(xComponents, yComponents int, rgba image.Image) (string, error)
+func blurhash.Decode(hash string, width, height, punch int) (image.Image, error)
+func blurhash.Components(hash string) (xComponents, yComponents int, err error)
+```
+
+Here’s a simple demonstration. Check [pkg.go.dev](https://pkg.go.dev/github.com/buckket/go-blurhash) for the full documentation.
+
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/buckket/go-blurhash"
+	"image/png"
+	"os"
+)
+
+func main() {
+	// Generate the BlurHash for a given image
+	imageFile, _ := os.Open("test.png")
+	loadedImage, err := png.Decode(imageFile)
+	str, _ := blurhash.Encode(4, 3, loadedImage)
+	if err != nil {
+		// Handle errors
+	}
+	fmt.Printf("Hash: %s\n", str)
+
+	// Generate an image for a given BlurHash
+	// Width will be 300px and Height will be 500px
+	// Punch specifies the contrasts and defaults to 1
+	img, err := blurhash.Decode(str, 300, 500, 1)
+	if err != nil {
+		// Handle errors
+	}
+	f, _ := os.Create("test_blur.png")
+	_ = png.Encode(f, img)
+	
+	// Get the x and y components used for encoding a given BlurHash
+	x, y, err := blurhash.Components("LFE.@D9F01_2%L%MIVD*9Goe-;WB")
+	if err != nil {
+		// Handle errors
+	}
+	fmt.Printf("xComponents: %d, yComponents: %d", x, y)
+}
+```
+
+## Limitations
+
+- Presumably a bit slower than the C implementation (TODO: Benchmarks)
+
+## Notes
+
+- As mentioned [here](https://github.com/woltapp/blurhash#how-fast-is-encoding-decoding), it’s best to
+generate very small images (~32x32px) via BlurHash and scale them up to the desired dimensions afterwards for optimal performance.
+- Since [#2](https://github.com/buckket/go-blurhash/pull/2) we diverted from the reference implementation by memorizing sRGBtoLinear values, thus increasing encoding speed at the cost of higher memory usage.
+- Starting with v1.1.0 the signature of blurhash.Encode() has changed slightly (see [#3](https://github.com/buckket/go-blurhash/issues/3)).
+
+## License
+
+ GNU GPLv3+
+ 

vendor/github.com/buckket/go-blurhash/base83/base83.go

@@ -0,0 +1,58 @@
+package base83
+
+import (
+	"fmt"
+	"math"
+	"strings"
+)
+
+const characters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~"
+
+// An InvalidCharacterError occurs when a characters is found which is not part of the Base83 character set.
+type InvalidCharacterError rune
+
+func (e InvalidCharacterError) Error() string {
+	return fmt.Sprintf("base83: invalid string (character %q out of range)", rune(e))
+}
+
+// An InvalidLengthError occurs when a given value cannot be encoded to a string of given length.
+type InvalidLengthError int
+
+func (e InvalidLengthError) Error() string {
+	return fmt.Sprintf("base83: invalid length (%d)", int(e))
+}
+
+// Encode will encode the given integer value to a Base83 string with given length.
+// If length is too short to encode the given value InvalidLengthError will be returned.
+func Encode(value, length int) (string, error) {
+	divisor := int(math.Pow(83, float64(length)))
+	if value/divisor != 0 {
+		return "", InvalidLengthError(length)
+	}
+	divisor /= 83
+
+	var str strings.Builder
+	str.Grow(length)
+	for i := 0; i < length; i++ {
+		if divisor <= 0 {
+			return "", InvalidLengthError(length)
+		}
+		digit := (value / divisor) % 83
+		divisor /= 83
+		str.WriteRune(rune(characters[digit]))
+	}
+
+	return str.String(), nil
+}
+
+// Decode will decode the given Base83 string to an integer.
+func Decode(str string) (value int, err error) {
+	for _, r := range str {
+		idx := strings.IndexRune(characters, r)
+		if idx == -1 {
+			return 0, InvalidCharacterError(r)
+		}
+		value = value*83 + idx
+	}
+	return value, nil
+}

vendor/github.com/buckket/go-blurhash/decode.go

@@ -0,0 +1,109 @@
+package blurhash
+
+import (
+	"fmt"
+	"github.com/buckket/go-blurhash/base83"
+	"image"
+	"image/color"
+	"math"
+)
+
+// An InvalidHashError occurs when the given hash is either too short or the length does not match its size flag.
+type InvalidHashError string
+
+func (e InvalidHashError) Error() string {
+	return fmt.Sprintf("blurhash: %s", string(e))
+}
+
+// Components decodes and returns the number of x and y components in the given BlurHash.
+func Components(hash string) (xComponents, yComponents int, err error) {
+	if len(hash) < 6 {
+		return 0, 0, InvalidHashError("hash is invalid (too short)")
+	}
+
+	sizeFlag, err := base83.Decode(string(hash[0]))
+	if err != nil {
+		return 0, 0, err
+	}
+
+	yComponents = (sizeFlag / 9) + 1
+	xComponents = (sizeFlag % 9) + 1
+
+	if len(hash) != 4+2*xComponents*yComponents {
+		return 0, 0, InvalidHashError("hash is invalid (length mismatch)")
+	}
+
+	return xComponents, yComponents, nil
+}
+
+// Decode generates an image of the given BlurHash with a size of width and height.
+// Punch is a multiplier that adjusts the contrast of the resulting image.
+func Decode(hash string, width, height, punch int) (image.Image, error) {
+	xComp, yComp, err := Components(hash)
+	if err != nil {
+		return nil, err
+	}
+
+	quantisedMaximumValue, err := base83.Decode(string(hash[1]))
+	if err != nil {
+		return nil, err
+	}
+	maximumValue := (float64(quantisedMaximumValue) + 1) / 166
+
+	if punch == 0 {
+		punch = 1
+	}
+
+	colors := make([][3]float64, xComp*yComp)
+
+	for i := range colors {
+		if i == 0 {
+			value, err := base83.Decode(hash[2:6])
+			if err != nil {
+				return nil, err
+			}
+			colors[i] = decodeDC(value)
+		} else {
+			value, err := base83.Decode(hash[4+i*2 : 6+i*2])
+			if err != nil {
+				return nil, err
+			}
+			colors[i] = decodeAC(value, maximumValue*float64(punch))
+		}
+	}
+
+	img := image.NewNRGBA(image.Rect(0, 0, width, height))
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			var r, g, b float64
+			for j := 0; j < yComp; j++ {
+				for i := 0; i < xComp; i++ {
+					basis := math.Cos(math.Pi*float64(x)*float64(i)/float64(width)) *
+						math.Cos(math.Pi*float64(y)*float64(j)/float64(height))
+					pcolor := colors[i+j*xComp]
+					r += pcolor[0] * basis
+					g += pcolor[1] * basis
+					b += pcolor[2] * basis
+				}
+			}
+			img.SetNRGBA(x, y, color.NRGBA{R: uint8(linearTosRGB(r)), G: uint8(linearTosRGB(g)), B: uint8(linearTosRGB(b)), A: 255})
+		}
+	}
+
+	return img, nil
+}
+
+func decodeDC(value int) [3]float64 {
+	return [3]float64{sRGBToLinear(value >> 16), sRGBToLinear(value >> 8 & 255), sRGBToLinear(value & 255)}
+}
+
+func decodeAC(value int, maximumValue float64) [3]float64 {
+	quantR := math.Floor(float64(value) / (19 * 19))
+	quantG := math.Mod(math.Floor(float64(value)/19), 19)
+	quantB := math.Mod(float64(value), 19)
+	sp := func(quant float64) float64 {
+		return signPow((quant-9)/9, 2.0) * maximumValue
+	}
+	return [3]float64{sp(quantR), sp(quantG), sp(quantB)}
+}

vendor/github.com/buckket/go-blurhash/encode.go

@@ -0,0 +1,164 @@
+package blurhash
+
+import (
+	"fmt"
+	"github.com/buckket/go-blurhash/base83"
+	"image"
+	"math"
+	"strings"
+)
+
+func init() {
+	initLinearTable(channelToLinear[:])
+}
+
+var channelToLinear [256]float64
+
+func initLinearTable(table []float64) {
+	for i := range table {
+		channelToLinear[i] = sRGBToLinear(i)
+	}
+}
+
+// An InvalidParameterError occurs when an invalid argument is passed to either the Decode or Encode function.
+type InvalidParameterError struct {
+	Value     int
+	Parameter string
+}
+
+func (e InvalidParameterError) Error() string {
+	return fmt.Sprintf("blurhash: %sComponents (%d) must be element of [1-9]", e.Parameter, e.Value)
+}
+
+// An EncodingError represents an error that occurred during the encoding of the given value.
+// This most likely means that your input image is invalid and can not be processed.
+type EncodingError string
+
+func (e EncodingError) Error() string {
+	return fmt.Sprintf("blurhash: %s", string(e))
+}
+
+// Encode calculates the Blurhash for an image using the given x and y component counts.
+// The x and y components have to be between 1 and 9 respectively.
+// The image must be of image.Image type.
+func Encode(xComponents int, yComponents int, rgba image.Image) (string, error) {
+	if xComponents < 1 || xComponents > 9 {
+		return "", InvalidParameterError{xComponents, "x"}
+	}
+	if yComponents < 1 || yComponents > 9 {
+		return "", InvalidParameterError{yComponents, "y"}
+	}
+
+	var blurhash strings.Builder
+	blurhash.Grow(4 + 2*xComponents*yComponents)
+
+	// Size Flag
+	str, err := base83.Encode((xComponents-1)+(yComponents-1)*9, 1)
+	if err != nil {
+		return "", EncodingError("could not encode size flag")
+	}
+	blurhash.WriteString(str)
+
+	factors := make([]float64, yComponents*xComponents*3)
+	multiplyBasisFunction(rgba, factors, xComponents, yComponents)
+
+	var maximumValue float64
+	var quantisedMaximumValue int
+	var acCount = xComponents*yComponents - 1
+	if acCount > 0 {
+		var actualMaximumValue float64
+		for i := 0; i < acCount*3; i++ {
+			actualMaximumValue = math.Max(math.Abs(factors[i+3]), actualMaximumValue)
+		}
+		quantisedMaximumValue = int(math.Max(0, math.Min(82, math.Floor(actualMaximumValue*166-0.5))))
+		maximumValue = (float64(quantisedMaximumValue) + 1) / 166
+	} else {
+		maximumValue = 1
+	}
+
+	// Quantised max AC component
+	str, err = base83.Encode(quantisedMaximumValue, 1)
+	if err != nil {
+		return "", EncodingError("could not encode quantised max AC component")
+	}
+	blurhash.WriteString(str)
+
+	// DC value
+	str, err = base83.Encode(encodeDC(factors[0], factors[1], factors[2]), 4)
+	if err != nil {
+		return "", EncodingError("could not encode DC value")
+	}
+	blurhash.WriteString(str)
+
+	// AC values
+	for i := 0; i < acCount; i++ {
+		str, err = base83.Encode(encodeAC(factors[3+(i*3+0)], factors[3+(i*3+1)], factors[3+(i*3+2)], maximumValue), 2)
+		if err != nil {
+			return "", EncodingError("could not encode AC value")
+		}
+		blurhash.WriteString(str)
+	}
+
+	if blurhash.Len() != 4+2*xComponents*yComponents {
+		return "", EncodingError("hash does not match expected size")
+	}
+
+	return blurhash.String(), nil
+}
+
+func multiplyBasisFunction(rgba image.Image, factors []float64, xComponents int, yComponents int) {
+	height := rgba.Bounds().Max.Y
+	width := rgba.Bounds().Max.X
+
+	xvalues := make([][]float64, xComponents)
+	for xComponent := 0; xComponent < xComponents; xComponent++ {
+		xvalues[xComponent] = make([]float64, width)
+		for x := 0; x < width; x++ {
+			xvalues[xComponent][x] = math.Cos(math.Pi * float64(xComponent) * float64(x) / float64(width))
+		}
+	}
+
+	yvalues := make([][]float64, yComponents)
+	for yComponent := 0; yComponent < yComponents; yComponent++ {
+		yvalues[yComponent] = make([]float64, height)
+		for y := 0; y < height; y++ {
+			yvalues[yComponent][y] = math.Cos(math.Pi * float64(yComponent) * float64(y) / float64(height))
+		}
+	}
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			rt, gt, bt, _ := rgba.At(x, y).RGBA()
+			lr := channelToLinear[rt>>8]
+			lg := channelToLinear[gt>>8]
+			lb := channelToLinear[bt>>8]
+
+			for yc := 0; yc < yComponents; yc++ {
+				for xc := 0; xc < xComponents; xc++ {
+
+					scale := 1 / float64(width*height)
+
+					if xc != 0 || yc != 0 {
+						scale = 2 / float64(width*height)
+					}
+
+					basis := xvalues[xc][x] * yvalues[yc][y]
+					factors[0+xc*3+yc*3*xComponents] += lr * basis * scale
+					factors[1+xc*3+yc*3*xComponents] += lg * basis * scale
+					factors[2+xc*3+yc*3*xComponents] += lb * basis * scale
+				}
+			}
+		}
+	}
+}
+
+func encodeDC(r, g, b float64) int {
+	return (linearTosRGB(r) << 16) + (linearTosRGB(g) << 8) + linearTosRGB(b)
+}
+
+func encodeAC(r, g, b, maximumValue float64) int {
+	quant := func(f float64) int {
+		return int(math.Max(0, math.Min(18, math.Floor(signPow(f/maximumValue, 0.5)*9+9.5))))
+	}
+	return quant(r)*19*19 + quant(g)*19 + quant(b)
+}

vendor/github.com/buckket/go-blurhash/go.mod

@@ -0,0 +1,3 @@
+module github.com/buckket/go-blurhash
+
+go 1.14

vendor/github.com/buckket/go-blurhash/utils.go

@@ -0,0 +1,23 @@
+package blurhash
+
+import "math"
+
+func linearTosRGB(value float64) int {
+	v := math.Max(0, math.Min(1, value))
+	if v <= 0.0031308 {
+		return int(v*12.92*255 + 0.5)
+	}
+	return int((1.055*math.Pow(v, 1/2.4)-0.055)*255 + 0.5)
+}
+
+func sRGBToLinear(value int) float64 {
+	v := float64(value) / 255
+	if v <= 0.04045 {
+		return v / 12.92
+	}
+	return math.Pow((v+0.055)/1.055, 2.4)
+}
+
+func signPow(value, exp float64) float64 {
+	return math.Copysign(math.Pow(math.Abs(value), exp), value)
+}

vendor/github.com/coreos/go-oidc/v3/LICENSE

@@ -0,0 +1,202 @@
+Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
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+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
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+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} {name of copyright owner}
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+

vendor/github.com/coreos/go-oidc/v3/NOTICE

@@ -0,0 +1,5 @@
+CoreOS Project
+Copyright 2014 CoreOS, Inc
+
+This product includes software developed at CoreOS, Inc.
+(http://www.coreos.com/).

vendor/github.com/coreos/go-oidc/v3/oidc/jose.go

@@ -0,0 +1,16 @@
+package oidc
+
+// JOSE asymmetric signing algorithm values as defined by RFC 7518
+//
+// see: https://tools.ietf.org/html/rfc7518#section-3.1
+const (
+	RS256 = "RS256" // RSASSA-PKCS-v1.5 using SHA-256
+	RS384 = "RS384" // RSASSA-PKCS-v1.5 using SHA-384
+	RS512 = "RS512" // RSASSA-PKCS-v1.5 using SHA-512
+	ES256 = "ES256" // ECDSA using P-256 and SHA-256
+	ES384 = "ES384" // ECDSA using P-384 and SHA-384
+	ES512 = "ES512" // ECDSA using P-521 and SHA-512
+	PS256 = "PS256" // RSASSA-PSS using SHA256 and MGF1-SHA256
+	PS384 = "PS384" // RSASSA-PSS using SHA384 and MGF1-SHA384
+	PS512 = "PS512" // RSASSA-PSS using SHA512 and MGF1-SHA512
+)

vendor/github.com/coreos/go-oidc/v3/oidc/jwks.go

@@ -0,0 +1,208 @@
+package oidc
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"sync"
+	"time"
+
+	jose "gopkg.in/square/go-jose.v2"
+)
+
+// NewRemoteKeySet returns a KeySet that can validate JSON web tokens by using HTTP
+// GETs to fetch JSON web token sets hosted at a remote URL. This is automatically
+// used by NewProvider using the URLs returned by OpenID Connect discovery, but is
+// exposed for providers that don't support discovery or to prevent round trips to the
+// discovery URL.
+//
+// The returned KeySet is a long lived verifier that caches keys based on cache-control
+// headers. Reuse a common remote key set instead of creating new ones as needed.
+func NewRemoteKeySet(ctx context.Context, jwksURL string) *RemoteKeySet {
+	return newRemoteKeySet(ctx, jwksURL, time.Now)
+}
+
+func newRemoteKeySet(ctx context.Context, jwksURL string, now func() time.Time) *RemoteKeySet {
+	if now == nil {
+		now = time.Now
+	}
+	return &RemoteKeySet{jwksURL: jwksURL, ctx: cloneContext(ctx), now: now}
+}
+
+// RemoteKeySet is a KeySet implementation that validates JSON web tokens against
+// a jwks_uri endpoint.
+type RemoteKeySet struct {
+	jwksURL string
+	ctx     context.Context
+	now     func() time.Time
+
+	// guard all other fields
+	mu sync.Mutex
+
+	// inflight suppresses parallel execution of updateKeys and allows
+	// multiple goroutines to wait for its result.
+	inflight *inflight
+
+	// A set of cached keys.
+	cachedKeys []jose.JSONWebKey
+}
+
+// inflight is used to wait on some in-flight request from multiple goroutines.
+type inflight struct {
+	doneCh chan struct{}
+
+	keys []jose.JSONWebKey
+	err  error
+}
+
+func newInflight() *inflight {
+	return &inflight{doneCh: make(chan struct{})}
+}
+
+// wait returns a channel that multiple goroutines can receive on. Once it returns
+// a value, the inflight request is done and result() can be inspected.
+func (i *inflight) wait() <-chan struct{} {
+	return i.doneCh
+}
+
+// done can only be called by a single goroutine. It records the result of the
+// inflight request and signals other goroutines that the result is safe to
+// inspect.
+func (i *inflight) done(keys []jose.JSONWebKey, err error) {
+	i.keys = keys
+	i.err = err
+	close(i.doneCh)
+}
+
+// result cannot be called until the wait() channel has returned a value.
+func (i *inflight) result() ([]jose.JSONWebKey, error) {
+	return i.keys, i.err
+}
+
+// VerifySignature validates a payload against a signature from the jwks_uri.
+//
+// Users MUST NOT call this method directly and should use an IDTokenVerifier
+// instead. This method skips critical validations such as 'alg' values and is
+// only exported to implement the KeySet interface.
+func (r *RemoteKeySet) VerifySignature(ctx context.Context, jwt string) ([]byte, error) {
+	jws, err := jose.ParseSigned(jwt)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: malformed jwt: %v", err)
+	}
+	return r.verify(ctx, jws)
+}
+
+func (r *RemoteKeySet) verify(ctx context.Context, jws *jose.JSONWebSignature) ([]byte, error) {
+	// We don't support JWTs signed with multiple signatures.
+	keyID := ""
+	for _, sig := range jws.Signatures {
+		keyID = sig.Header.KeyID
+		break
+	}
+
+	keys := r.keysFromCache()
+	for _, key := range keys {
+		if keyID == "" || key.KeyID == keyID {
+			if payload, err := jws.Verify(&key); err == nil {
+				return payload, nil
+			}
+		}
+	}
+
+	// If the kid doesn't match, check for new keys from the remote. This is the
+	// strategy recommended by the spec.
+	//
+	// https://openid.net/specs/openid-connect-core-1_0.html#RotateSigKeys
+	keys, err := r.keysFromRemote(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("fetching keys %v", err)
+	}
+
+	for _, key := range keys {
+		if keyID == "" || key.KeyID == keyID {
+			if payload, err := jws.Verify(&key); err == nil {
+				return payload, nil
+			}
+		}
+	}
+	return nil, errors.New("failed to verify id token signature")
+}
+
+func (r *RemoteKeySet) keysFromCache() (keys []jose.JSONWebKey) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.cachedKeys
+}
+
+// keysFromRemote syncs the key set from the remote set, records the values in the
+// cache, and returns the key set.
+func (r *RemoteKeySet) keysFromRemote(ctx context.Context) ([]jose.JSONWebKey, error) {
+	// Need to lock to inspect the inflight request field.
+	r.mu.Lock()
+	// If there's not a current inflight request, create one.
+	if r.inflight == nil {
+		r.inflight = newInflight()
+
+		// This goroutine has exclusive ownership over the current inflight
+		// request. It releases the resource by nil'ing the inflight field
+		// once the goroutine is done.
+		go func() {
+			// Sync keys and finish inflight when that's done.
+			keys, err := r.updateKeys()
+
+			r.inflight.done(keys, err)
+
+			// Lock to update the keys and indicate that there is no longer an
+			// inflight request.
+			r.mu.Lock()
+			defer r.mu.Unlock()
+
+			if err == nil {
+				r.cachedKeys = keys
+			}
+
+			// Free inflight so a different request can run.
+			r.inflight = nil
+		}()
+	}
+	inflight := r.inflight
+	r.mu.Unlock()
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case <-inflight.wait():
+		return inflight.result()
+	}
+}
+
+func (r *RemoteKeySet) updateKeys() ([]jose.JSONWebKey, error) {
+	req, err := http.NewRequest("GET", r.jwksURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: can't create request: %v", err)
+	}
+
+	resp, err := doRequest(r.ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: get keys failed %v", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read response body: %v", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("oidc: get keys failed: %s %s", resp.Status, body)
+	}
+
+	var keySet jose.JSONWebKeySet
+	err = unmarshalResp(resp, body, &keySet)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: failed to decode keys: %v %s", err, body)
+	}
+	return keySet.Keys, nil
+}

vendor/github.com/coreos/go-oidc/v3/oidc/oidc.go

@@ -0,0 +1,459 @@
+// Package oidc implements OpenID Connect client logic for the golang.org/x/oauth2 package.
+package oidc
+
+import (
+	"context"
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"hash"
+	"io/ioutil"
+	"mime"
+	"net/http"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+	jose "gopkg.in/square/go-jose.v2"
+)
+
+const (
+	// ScopeOpenID is the mandatory scope for all OpenID Connect OAuth2 requests.
+	ScopeOpenID = "openid"
+
+	// ScopeOfflineAccess is an optional scope defined by OpenID Connect for requesting
+	// OAuth2 refresh tokens.
+	//
+	// Support for this scope differs between OpenID Connect providers. For instance
+	// Google rejects it, favoring appending "access_type=offline" as part of the
+	// authorization request instead.
+	//
+	// See: https://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess
+	ScopeOfflineAccess = "offline_access"
+)
+
+var (
+	errNoAtHash      = errors.New("id token did not have an access token hash")
+	errInvalidAtHash = errors.New("access token hash does not match value in ID token")
+)
+
+// ClientContext returns a new Context that carries the provided HTTP client.
+//
+// This method sets the same context key used by the golang.org/x/oauth2 package,
+// so the returned context works for that package too.
+//
+//    myClient := &http.Client{}
+//    ctx := oidc.ClientContext(parentContext, myClient)
+//
+//    // This will use the custom client
+//    provider, err := oidc.NewProvider(ctx, "https://accounts.example.com")
+//
+func ClientContext(ctx context.Context, client *http.Client) context.Context {
+	return context.WithValue(ctx, oauth2.HTTPClient, client)
+}
+
+// cloneContext copies a context's bag-of-values into a new context that isn't
+// associated with its cancelation. This is used to initialize remote keys sets
+// which run in the background and aren't associated with the initial context.
+func cloneContext(ctx context.Context) context.Context {
+	cp := context.Background()
+	if c, ok := ctx.Value(oauth2.HTTPClient).(*http.Client); ok {
+		cp = ClientContext(cp, c)
+	}
+	return cp
+}
+
+func doRequest(ctx context.Context, req *http.Request) (*http.Response, error) {
+	client := http.DefaultClient
+	if c, ok := ctx.Value(oauth2.HTTPClient).(*http.Client); ok {
+		client = c
+	}
+	return client.Do(req.WithContext(ctx))
+}
+
+// Provider represents an OpenID Connect server's configuration.
+type Provider struct {
+	issuer      string
+	authURL     string
+	tokenURL    string
+	userInfoURL string
+	algorithms  []string
+
+	// Raw claims returned by the server.
+	rawClaims []byte
+
+	remoteKeySet KeySet
+}
+
+type cachedKeys struct {
+	keys   []jose.JSONWebKey
+	expiry time.Time
+}
+
+type providerJSON struct {
+	Issuer      string   `json:"issuer"`
+	AuthURL     string   `json:"authorization_endpoint"`
+	TokenURL    string   `json:"token_endpoint"`
+	JWKSURL     string   `json:"jwks_uri"`
+	UserInfoURL string   `json:"userinfo_endpoint"`
+	Algorithms  []string `json:"id_token_signing_alg_values_supported"`
+}
+
+// supportedAlgorithms is a list of algorithms explicitly supported by this
+// package. If a provider supports other algorithms, such as HS256 or none,
+// those values won't be passed to the IDTokenVerifier.
+var supportedAlgorithms = map[string]bool{
+	RS256: true,
+	RS384: true,
+	RS512: true,
+	ES256: true,
+	ES384: true,
+	ES512: true,
+	PS256: true,
+	PS384: true,
+	PS512: true,
+}
+
+// NewProvider uses the OpenID Connect discovery mechanism to construct a Provider.
+//
+// The issuer is the URL identifier for the service. For example: "https://accounts.google.com"
+// or "https://login.salesforce.com".
+func NewProvider(ctx context.Context, issuer string) (*Provider, error) {
+	wellKnown := strings.TrimSuffix(issuer, "/") + "/.well-known/openid-configuration"
+	req, err := http.NewRequest("GET", wellKnown, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := doRequest(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read response body: %v", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("%s: %s", resp.Status, body)
+	}
+
+	var p providerJSON
+	err = unmarshalResp(resp, body, &p)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: failed to decode provider discovery object: %v", err)
+	}
+
+	if p.Issuer != issuer {
+		return nil, fmt.Errorf("oidc: issuer did not match the issuer returned by provider, expected %q got %q", issuer, p.Issuer)
+	}
+	var algs []string
+	for _, a := range p.Algorithms {
+		if supportedAlgorithms[a] {
+			algs = append(algs, a)
+		}
+	}
+	return &Provider{
+		issuer:       p.Issuer,
+		authURL:      p.AuthURL,
+		tokenURL:     p.TokenURL,
+		userInfoURL:  p.UserInfoURL,
+		algorithms:   algs,
+		rawClaims:    body,
+		remoteKeySet: NewRemoteKeySet(cloneContext(ctx), p.JWKSURL),
+	}, nil
+}
+
+// Claims unmarshals raw fields returned by the server during discovery.
+//
+//    var claims struct {
+//        ScopesSupported []string `json:"scopes_supported"`
+//        ClaimsSupported []string `json:"claims_supported"`
+//    }
+//
+//    if err := provider.Claims(&claims); err != nil {
+//        // handle unmarshaling error
+//    }
+//
+// For a list of fields defined by the OpenID Connect spec see:
+// https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata
+func (p *Provider) Claims(v interface{}) error {
+	if p.rawClaims == nil {
+		return errors.New("oidc: claims not set")
+	}
+	return json.Unmarshal(p.rawClaims, v)
+}
+
+// Endpoint returns the OAuth2 auth and token endpoints for the given provider.
+func (p *Provider) Endpoint() oauth2.Endpoint {
+	return oauth2.Endpoint{AuthURL: p.authURL, TokenURL: p.tokenURL}
+}
+
+// UserInfo represents the OpenID Connect userinfo claims.
+type UserInfo struct {
+	Subject       string `json:"sub"`
+	Profile       string `json:"profile"`
+	Email         string `json:"email"`
+	EmailVerified bool   `json:"email_verified"`
+
+	claims []byte
+}
+
+type userInfoRaw struct {
+	Subject string `json:"sub"`
+	Profile string `json:"profile"`
+	Email   string `json:"email"`
+	// Handle providers that return email_verified as a string
+	// https://forums.aws.amazon.com/thread.jspa?messageID=949441&#949441 and
+	// https://discuss.elastic.co/t/openid-error-after-authenticating-against-aws-cognito/206018/11
+	EmailVerified stringAsBool `json:"email_verified"`
+}
+
+// Claims unmarshals the raw JSON object claims into the provided object.
+func (u *UserInfo) Claims(v interface{}) error {
+	if u.claims == nil {
+		return errors.New("oidc: claims not set")
+	}
+	return json.Unmarshal(u.claims, v)
+}
+
+// UserInfo uses the token source to query the provider's user info endpoint.
+func (p *Provider) UserInfo(ctx context.Context, tokenSource oauth2.TokenSource) (*UserInfo, error) {
+	if p.userInfoURL == "" {
+		return nil, errors.New("oidc: user info endpoint is not supported by this provider")
+	}
+
+	req, err := http.NewRequest("GET", p.userInfoURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: create GET request: %v", err)
+	}
+
+	token, err := tokenSource.Token()
+	if err != nil {
+		return nil, fmt.Errorf("oidc: get access token: %v", err)
+	}
+	token.SetAuthHeader(req)
+
+	resp, err := doRequest(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("%s: %s", resp.Status, body)
+	}
+
+	ct := resp.Header.Get("Content-Type")
+	mediaType, _, parseErr := mime.ParseMediaType(ct)
+	if parseErr == nil && mediaType == "application/jwt" {
+		payload, err := p.remoteKeySet.VerifySignature(ctx, string(body))
+		if err != nil {
+			return nil, fmt.Errorf("oidc: invalid userinfo jwt signature %v", err)
+		}
+		body = payload
+	}
+
+	var userInfo userInfoRaw
+	if err := json.Unmarshal(body, &userInfo); err != nil {
+		return nil, fmt.Errorf("oidc: failed to decode userinfo: %v", err)
+	}
+	return &UserInfo{
+		Subject:       userInfo.Subject,
+		Profile:       userInfo.Profile,
+		Email:         userInfo.Email,
+		EmailVerified: bool(userInfo.EmailVerified),
+		claims:        body,
+	}, nil
+}
+
+// IDToken is an OpenID Connect extension that provides a predictable representation
+// of an authorization event.
+//
+// The ID Token only holds fields OpenID Connect requires. To access additional
+// claims returned by the server, use the Claims method.
+type IDToken struct {
+	// The URL of the server which issued this token. OpenID Connect
+	// requires this value always be identical to the URL used for
+	// initial discovery.
+	//
+	// Note: Because of a known issue with Google Accounts' implementation
+	// this value may differ when using Google.
+	//
+	// See: https://developers.google.com/identity/protocols/OpenIDConnect#obtainuserinfo
+	Issuer string
+
+	// The client ID, or set of client IDs, that this token is issued for. For
+	// common uses, this is the client that initialized the auth flow.
+	//
+	// This package ensures the audience contains an expected value.
+	Audience []string
+
+	// A unique string which identifies the end user.
+	Subject string
+
+	// Expiry of the token. Ths package will not process tokens that have
+	// expired unless that validation is explicitly turned off.
+	Expiry time.Time
+	// When the token was issued by the provider.
+	IssuedAt time.Time
+
+	// Initial nonce provided during the authentication redirect.
+	//
+	// This package does NOT provided verification on the value of this field
+	// and it's the user's responsibility to ensure it contains a valid value.
+	Nonce string
+
+	// at_hash claim, if set in the ID token. Callers can verify an access token
+	// that corresponds to the ID token using the VerifyAccessToken method.
+	AccessTokenHash string
+
+	// signature algorithm used for ID token, needed to compute a verification hash of an
+	// access token
+	sigAlgorithm string
+
+	// Raw payload of the id_token.
+	claims []byte
+
+	// Map of distributed claim names to claim sources
+	distributedClaims map[string]claimSource
+}
+
+// Claims unmarshals the raw JSON payload of the ID Token into a provided struct.
+//
+//		idToken, err := idTokenVerifier.Verify(rawIDToken)
+//		if err != nil {
+//			// handle error
+//		}
+//		var claims struct {
+//			Email         string `json:"email"`
+//			EmailVerified bool   `json:"email_verified"`
+//		}
+//		if err := idToken.Claims(&claims); err != nil {
+//			// handle error
+//		}
+//
+func (i *IDToken) Claims(v interface{}) error {
+	if i.claims == nil {
+		return errors.New("oidc: claims not set")
+	}
+	return json.Unmarshal(i.claims, v)
+}
+
+// VerifyAccessToken verifies that the hash of the access token that corresponds to the iD token
+// matches the hash in the id token. It returns an error if the hashes  don't match.
+// It is the caller's responsibility to ensure that the optional access token hash is present for the ID token
+// before calling this method. See https://openid.net/specs/openid-connect-core-1_0.html#CodeIDToken
+func (i *IDToken) VerifyAccessToken(accessToken string) error {
+	if i.AccessTokenHash == "" {
+		return errNoAtHash
+	}
+	var h hash.Hash
+	switch i.sigAlgorithm {
+	case RS256, ES256, PS256:
+		h = sha256.New()
+	case RS384, ES384, PS384:
+		h = sha512.New384()
+	case RS512, ES512, PS512:
+		h = sha512.New()
+	default:
+		return fmt.Errorf("oidc: unsupported signing algorithm %q", i.sigAlgorithm)
+	}
+	h.Write([]byte(accessToken)) // hash documents that Write will never return an error
+	sum := h.Sum(nil)[:h.Size()/2]
+	actual := base64.RawURLEncoding.EncodeToString(sum)
+	if actual != i.AccessTokenHash {
+		return errInvalidAtHash
+	}
+	return nil
+}
+
+type idToken struct {
+	Issuer       string                 `json:"iss"`
+	Subject      string                 `json:"sub"`
+	Audience     audience               `json:"aud"`
+	Expiry       jsonTime               `json:"exp"`
+	IssuedAt     jsonTime               `json:"iat"`
+	NotBefore    *jsonTime              `json:"nbf"`
+	Nonce        string                 `json:"nonce"`
+	AtHash       string                 `json:"at_hash"`
+	ClaimNames   map[string]string      `json:"_claim_names"`
+	ClaimSources map[string]claimSource `json:"_claim_sources"`
+}
+
+type claimSource struct {
+	Endpoint    string `json:"endpoint"`
+	AccessToken string `json:"access_token"`
+}
+
+type stringAsBool bool
+
+func (sb *stringAsBool) UnmarshalJSON(b []byte) error {
+	switch string(b) {
+	case "true", `"true"`:
+		*sb = stringAsBool(true)
+	case "false", `"false"`:
+		*sb = stringAsBool(false)
+	default:
+		return errors.New("invalid value for boolean")
+	}
+	return nil
+}
+
+type audience []string
+
+func (a *audience) UnmarshalJSON(b []byte) error {
+	var s string
+	if json.Unmarshal(b, &s) == nil {
+		*a = audience{s}
+		return nil
+	}
+	var auds []string
+	if err := json.Unmarshal(b, &auds); err != nil {
+		return err
+	}
+	*a = audience(auds)
+	return nil
+}
+
+type jsonTime time.Time
+
+func (j *jsonTime) UnmarshalJSON(b []byte) error {
+	var n json.Number
+	if err := json.Unmarshal(b, &n); err != nil {
+		return err
+	}
+	var unix int64
+
+	if t, err := n.Int64(); err == nil {
+		unix = t
+	} else {
+		f, err := n.Float64()
+		if err != nil {
+			return err
+		}
+		unix = int64(f)
+	}
+	*j = jsonTime(time.Unix(unix, 0))
+	return nil
+}
+
+func unmarshalResp(r *http.Response, body []byte, v interface{}) error {
+	err := json.Unmarshal(body, &v)
+	if err == nil {
+		return nil
+	}
+	ct := r.Header.Get("Content-Type")
+	mediaType, _, parseErr := mime.ParseMediaType(ct)
+	if parseErr == nil && mediaType == "application/json" {
+		return fmt.Errorf("got Content-Type = application/json, but could not unmarshal as JSON: %v", err)
+	}
+	return fmt.Errorf("expected Content-Type = application/json, got %q: %v", ct, err)
+}

vendor/github.com/coreos/go-oidc/v3/oidc/verify.go

@@ -0,0 +1,336 @@
+package oidc
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+	jose "gopkg.in/square/go-jose.v2"
+)
+
+const (
+	issuerGoogleAccounts         = "https://accounts.google.com"
+	issuerGoogleAccountsNoScheme = "accounts.google.com"
+)
+
+// KeySet is a set of publc JSON Web Keys that can be used to validate the signature
+// of JSON web tokens. This is expected to be backed by a remote key set through
+// provider metadata discovery or an in-memory set of keys delivered out-of-band.
+type KeySet interface {
+	// VerifySignature parses the JSON web token, verifies the signature, and returns
+	// the raw payload. Header and claim fields are validated by other parts of the
+	// package. For example, the KeySet does not need to check values such as signature
+	// algorithm, issuer, and audience since the IDTokenVerifier validates these values
+	// independently.
+	//
+	// If VerifySignature makes HTTP requests to verify the token, it's expected to
+	// use any HTTP client associated with the context through ClientContext.
+	VerifySignature(ctx context.Context, jwt string) (payload []byte, err error)
+}
+
+// IDTokenVerifier provides verification for ID Tokens.
+type IDTokenVerifier struct {
+	keySet KeySet
+	config *Config
+	issuer string
+}
+
+// NewVerifier returns a verifier manually constructed from a key set and issuer URL.
+//
+// It's easier to use provider discovery to construct an IDTokenVerifier than creating
+// one directly. This method is intended to be used with provider that don't support
+// metadata discovery, or avoiding round trips when the key set URL is already known.
+//
+// This constructor can be used to create a verifier directly using the issuer URL and
+// JSON Web Key Set URL without using discovery:
+//
+//		keySet := oidc.NewRemoteKeySet(ctx, "https://www.googleapis.com/oauth2/v3/certs")
+//		verifier := oidc.NewVerifier("https://accounts.google.com", keySet, config)
+//
+// Since KeySet is an interface, this constructor can also be used to supply custom
+// public key sources. For example, if a user wanted to supply public keys out-of-band
+// and hold them statically in-memory:
+//
+//		// Custom KeySet implementation.
+//		keySet := newStatisKeySet(publicKeys...)
+//
+//		// Verifier uses the custom KeySet implementation.
+//		verifier := oidc.NewVerifier("https://auth.example.com", keySet, config)
+//
+func NewVerifier(issuerURL string, keySet KeySet, config *Config) *IDTokenVerifier {
+	return &IDTokenVerifier{keySet: keySet, config: config, issuer: issuerURL}
+}
+
+// Config is the configuration for an IDTokenVerifier.
+type Config struct {
+	// Expected audience of the token. For a majority of the cases this is expected to be
+	// the ID of the client that initialized the login flow. It may occasionally differ if
+	// the provider supports the authorizing party (azp) claim.
+	//
+	// If not provided, users must explicitly set SkipClientIDCheck.
+	ClientID string
+	// If specified, only this set of algorithms may be used to sign the JWT.
+	//
+	// If the IDTokenVerifier is created from a provider with (*Provider).Verifier, this
+	// defaults to the set of algorithms the provider supports. Otherwise this values
+	// defaults to RS256.
+	SupportedSigningAlgs []string
+
+	// If true, no ClientID check performed. Must be true if ClientID field is empty.
+	SkipClientIDCheck bool
+	// If true, token expiry is not checked.
+	SkipExpiryCheck bool
+
+	// SkipIssuerCheck is intended for specialized cases where the the caller wishes to
+	// defer issuer validation. When enabled, callers MUST independently verify the Token's
+	// Issuer is a known good value.
+	//
+	// Mismatched issuers often indicate client mis-configuration. If mismatches are
+	// unexpected, evaluate if the provided issuer URL is incorrect instead of enabling
+	// this option.
+	SkipIssuerCheck bool
+
+	// Time function to check Token expiry. Defaults to time.Now
+	Now func() time.Time
+}
+
+// Verifier returns an IDTokenVerifier that uses the provider's key set to verify JWTs.
+//
+// The returned IDTokenVerifier is tied to the Provider's context and its behavior is
+// undefined once the Provider's context is canceled.
+func (p *Provider) Verifier(config *Config) *IDTokenVerifier {
+	if len(config.SupportedSigningAlgs) == 0 && len(p.algorithms) > 0 {
+		// Make a copy so we don't modify the config values.
+		cp := &Config{}
+		*cp = *config
+		cp.SupportedSigningAlgs = p.algorithms
+		config = cp
+	}
+	return NewVerifier(p.issuer, p.remoteKeySet, config)
+}
+
+func parseJWT(p string) ([]byte, error) {
+	parts := strings.Split(p, ".")
+	if len(parts) < 2 {
+		return nil, fmt.Errorf("oidc: malformed jwt, expected 3 parts got %d", len(parts))
+	}
+	payload, err := base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("oidc: malformed jwt payload: %v", err)
+	}
+	return payload, nil
+}
+
+func contains(sli []string, ele string) bool {
+	for _, s := range sli {
+		if s == ele {
+			return true
+		}
+	}
+	return false
+}
+
+// Returns the Claims from the distributed JWT token
+func resolveDistributedClaim(ctx context.Context, verifier *IDTokenVerifier, src claimSource) ([]byte, error) {
+	req, err := http.NewRequest("GET", src.Endpoint, nil)
+	if err != nil {
+		return nil, fmt.Errorf("malformed request: %v", err)
+	}
+	if src.AccessToken != "" {
+		req.Header.Set("Authorization", "Bearer "+src.AccessToken)
+	}
+
+	resp, err := doRequest(ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: Request to endpoint failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read response body: %v", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("oidc: request failed: %v", resp.StatusCode)
+	}
+
+	token, err := verifier.Verify(ctx, string(body))
+	if err != nil {
+		return nil, fmt.Errorf("malformed response body: %v", err)
+	}
+
+	return token.claims, nil
+}
+
+func parseClaim(raw []byte, name string, v interface{}) error {
+	var parsed map[string]json.RawMessage
+	if err := json.Unmarshal(raw, &parsed); err != nil {
+		return err
+	}
+
+	val, ok := parsed[name]
+	if !ok {
+		return fmt.Errorf("claim doesn't exist: %s", name)
+	}
+
+	return json.Unmarshal([]byte(val), v)
+}
+
+// Verify parses a raw ID Token, verifies it's been signed by the provider, performs
+// any additional checks depending on the Config, and returns the payload.
+//
+// Verify does NOT do nonce validation, which is the callers responsibility.
+//
+// See: https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation
+//
+//    oauth2Token, err := oauth2Config.Exchange(ctx, r.URL.Query().Get("code"))
+//    if err != nil {
+//        // handle error
+//    }
+//
+//    // Extract the ID Token from oauth2 token.
+//    rawIDToken, ok := oauth2Token.Extra("id_token").(string)
+//    if !ok {
+//        // handle error
+//    }
+//
+//    token, err := verifier.Verify(ctx, rawIDToken)
+//
+func (v *IDTokenVerifier) Verify(ctx context.Context, rawIDToken string) (*IDToken, error) {
+	jws, err := jose.ParseSigned(rawIDToken)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: malformed jwt: %v", err)
+	}
+
+	// Throw out tokens with invalid claims before trying to verify the token. This lets
+	// us do cheap checks before possibly re-syncing keys.
+	payload, err := parseJWT(rawIDToken)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: malformed jwt: %v", err)
+	}
+	var token idToken
+	if err := json.Unmarshal(payload, &token); err != nil {
+		return nil, fmt.Errorf("oidc: failed to unmarshal claims: %v", err)
+	}
+
+	distributedClaims := make(map[string]claimSource)
+
+	//step through the token to map claim names to claim sources"
+	for cn, src := range token.ClaimNames {
+		if src == "" {
+			return nil, fmt.Errorf("oidc: failed to obtain source from claim name")
+		}
+		s, ok := token.ClaimSources[src]
+		if !ok {
+			return nil, fmt.Errorf("oidc: source does not exist")
+		}
+		distributedClaims[cn] = s
+	}
+
+	t := &IDToken{
+		Issuer:            token.Issuer,
+		Subject:           token.Subject,
+		Audience:          []string(token.Audience),
+		Expiry:            time.Time(token.Expiry),
+		IssuedAt:          time.Time(token.IssuedAt),
+		Nonce:             token.Nonce,
+		AccessTokenHash:   token.AtHash,
+		claims:            payload,
+		distributedClaims: distributedClaims,
+	}
+
+	// Check issuer.
+	if !v.config.SkipIssuerCheck && t.Issuer != v.issuer {
+		// Google sometimes returns "accounts.google.com" as the issuer claim instead of
+		// the required "https://accounts.google.com". Detect this case and allow it only
+		// for Google.
+		//
+		// We will not add hooks to let other providers go off spec like this.
+		if !(v.issuer == issuerGoogleAccounts && t.Issuer == issuerGoogleAccountsNoScheme) {
+			return nil, fmt.Errorf("oidc: id token issued by a different provider, expected %q got %q", v.issuer, t.Issuer)
+		}
+	}
+
+	// If a client ID has been provided, make sure it's part of the audience. SkipClientIDCheck must be true if ClientID is empty.
+	//
+	// This check DOES NOT ensure that the ClientID is the party to which the ID Token was issued (i.e. Authorized party).
+	if !v.config.SkipClientIDCheck {
+		if v.config.ClientID != "" {
+			if !contains(t.Audience, v.config.ClientID) {
+				return nil, fmt.Errorf("oidc: expected audience %q got %q", v.config.ClientID, t.Audience)
+			}
+		} else {
+			return nil, fmt.Errorf("oidc: invalid configuration, clientID must be provided or SkipClientIDCheck must be set")
+		}
+	}
+
+	// If a SkipExpiryCheck is false, make sure token is not expired.
+	if !v.config.SkipExpiryCheck {
+		now := time.Now
+		if v.config.Now != nil {
+			now = v.config.Now
+		}
+		nowTime := now()
+
+		if t.Expiry.Before(nowTime) {
+			return nil, fmt.Errorf("oidc: token is expired (Token Expiry: %v)", t.Expiry)
+		}
+
+		// If nbf claim is provided in token, ensure that it is indeed in the past.
+		if token.NotBefore != nil {
+			nbfTime := time.Time(*token.NotBefore)
+			leeway := 1 * time.Minute
+
+			if nowTime.Add(leeway).Before(nbfTime) {
+				return nil, fmt.Errorf("oidc: current time %v before the nbf (not before) time: %v", nowTime, nbfTime)
+			}
+		}
+	}
+
+	switch len(jws.Signatures) {
+	case 0:
+		return nil, fmt.Errorf("oidc: id token not signed")
+	case 1:
+	default:
+		return nil, fmt.Errorf("oidc: multiple signatures on id token not supported")
+	}
+
+	sig := jws.Signatures[0]
+	supportedSigAlgs := v.config.SupportedSigningAlgs
+	if len(supportedSigAlgs) == 0 {
+		supportedSigAlgs = []string{RS256}
+	}
+
+	if !contains(supportedSigAlgs, sig.Header.Algorithm) {
+		return nil, fmt.Errorf("oidc: id token signed with unsupported algorithm, expected %q got %q", supportedSigAlgs, sig.Header.Algorithm)
+	}
+
+	t.sigAlgorithm = sig.Header.Algorithm
+
+	gotPayload, err := v.keySet.VerifySignature(ctx, rawIDToken)
+	if err != nil {
+		return nil, fmt.Errorf("failed to verify signature: %v", err)
+	}
+
+	// Ensure that the payload returned by the square actually matches the payload parsed earlier.
+	if !bytes.Equal(gotPayload, payload) {
+		return nil, errors.New("oidc: internal error, payload parsed did not match previous payload")
+	}
+
+	return t, nil
+}
+
+// Nonce returns an auth code option which requires the ID Token created by the
+// OpenID Connect provider to contain the specified nonce.
+func Nonce(nonce string) oauth2.AuthCodeOption {
+	return oauth2.SetAuthURLParam("nonce", nonce)
+}

vendor/github.com/cpuguy83/go-md2man/v2/LICENSE.md

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Brian Goff
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/cpuguy83/go-md2man/v2/md2man/md2man.go

@@ -0,0 +1,14 @@
+package md2man
+
+import (
+	"github.com/russross/blackfriday/v2"
+)
+
+// Render converts a markdown document into a roff formatted document.
+func Render(doc []byte) []byte {
+	renderer := NewRoffRenderer()
+
+	return blackfriday.Run(doc,
+		[]blackfriday.Option{blackfriday.WithRenderer(renderer),
+			blackfriday.WithExtensions(renderer.GetExtensions())}...)
+}

vendor/github.com/cpuguy83/go-md2man/v2/md2man/roff.go

@@ -0,0 +1,336 @@
+package md2man
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/russross/blackfriday/v2"
+)
+
+// roffRenderer implements the blackfriday.Renderer interface for creating
+// roff format (manpages) from markdown text
+type roffRenderer struct {
+	extensions   blackfriday.Extensions
+	listCounters []int
+	firstHeader  bool
+	firstDD      bool
+	listDepth    int
+}
+
+const (
+	titleHeader      = ".TH "
+	topLevelHeader   = "\n\n.SH "
+	secondLevelHdr   = "\n.SH "
+	otherHeader      = "\n.SS "
+	crTag            = "\n"
+	emphTag          = "\\fI"
+	emphCloseTag     = "\\fP"
+	strongTag        = "\\fB"
+	strongCloseTag   = "\\fP"
+	breakTag         = "\n.br\n"
+	paraTag          = "\n.PP\n"
+	hruleTag         = "\n.ti 0\n\\l'\\n(.lu'\n"
+	linkTag          = "\n\\[la]"
+	linkCloseTag     = "\\[ra]"
+	codespanTag      = "\\fB\\fC"
+	codespanCloseTag = "\\fR"
+	codeTag          = "\n.PP\n.RS\n\n.nf\n"
+	codeCloseTag     = "\n.fi\n.RE\n"
+	quoteTag         = "\n.PP\n.RS\n"
+	quoteCloseTag    = "\n.RE\n"
+	listTag          = "\n.RS\n"
+	listCloseTag     = "\n.RE\n"
+	dtTag            = "\n.TP\n"
+	dd2Tag           = "\n"
+	tableStart       = "\n.TS\nallbox;\n"
+	tableEnd         = ".TE\n"
+	tableCellStart   = "T{\n"
+	tableCellEnd     = "\nT}\n"
+)
+
+// NewRoffRenderer creates a new blackfriday Renderer for generating roff documents
+// from markdown
+func NewRoffRenderer() *roffRenderer { // nolint: golint
+	var extensions blackfriday.Extensions
+
+	extensions |= blackfriday.NoIntraEmphasis
+	extensions |= blackfriday.Tables
+	extensions |= blackfriday.FencedCode
+	extensions |= blackfriday.SpaceHeadings
+	extensions |= blackfriday.Footnotes
+	extensions |= blackfriday.Titleblock
+	extensions |= blackfriday.DefinitionLists
+	return &roffRenderer{
+		extensions: extensions,
+	}
+}
+
+// GetExtensions returns the list of extensions used by this renderer implementation
+func (r *roffRenderer) GetExtensions() blackfriday.Extensions {
+	return r.extensions
+}
+
+// RenderHeader handles outputting the header at document start
+func (r *roffRenderer) RenderHeader(w io.Writer, ast *blackfriday.Node) {
+	// disable hyphenation
+	out(w, ".nh\n")
+}
+
+// RenderFooter handles outputting the footer at the document end; the roff
+// renderer has no footer information
+func (r *roffRenderer) RenderFooter(w io.Writer, ast *blackfriday.Node) {
+}
+
+// RenderNode is called for each node in a markdown document; based on the node
+// type the equivalent roff output is sent to the writer
+func (r *roffRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+
+	var walkAction = blackfriday.GoToNext
+
+	switch node.Type {
+	case blackfriday.Text:
+		escapeSpecialChars(w, node.Literal)
+	case blackfriday.Softbreak:
+		out(w, crTag)
+	case blackfriday.Hardbreak:
+		out(w, breakTag)
+	case blackfriday.Emph:
+		if entering {
+			out(w, emphTag)
+		} else {
+			out(w, emphCloseTag)
+		}
+	case blackfriday.Strong:
+		if entering {
+			out(w, strongTag)
+		} else {
+			out(w, strongCloseTag)
+		}
+	case blackfriday.Link:
+		if !entering {
+			out(w, linkTag+string(node.LinkData.Destination)+linkCloseTag)
+		}
+	case blackfriday.Image:
+		// ignore images
+		walkAction = blackfriday.SkipChildren
+	case blackfriday.Code:
+		out(w, codespanTag)
+		escapeSpecialChars(w, node.Literal)
+		out(w, codespanCloseTag)
+	case blackfriday.Document:
+		break
+	case blackfriday.Paragraph:
+		// roff .PP markers break lists
+		if r.listDepth > 0 {
+			return blackfriday.GoToNext
+		}
+		if entering {
+			out(w, paraTag)
+		} else {
+			out(w, crTag)
+		}
+	case blackfriday.BlockQuote:
+		if entering {
+			out(w, quoteTag)
+		} else {
+			out(w, quoteCloseTag)
+		}
+	case blackfriday.Heading:
+		r.handleHeading(w, node, entering)
+	case blackfriday.HorizontalRule:
+		out(w, hruleTag)
+	case blackfriday.List:
+		r.handleList(w, node, entering)
+	case blackfriday.Item:
+		r.handleItem(w, node, entering)
+	case blackfriday.CodeBlock:
+		out(w, codeTag)
+		escapeSpecialChars(w, node.Literal)
+		out(w, codeCloseTag)
+	case blackfriday.Table:
+		r.handleTable(w, node, entering)
+	case blackfriday.TableHead:
+	case blackfriday.TableBody:
+	case blackfriday.TableRow:
+		// no action as cell entries do all the nroff formatting
+		return blackfriday.GoToNext
+	case blackfriday.TableCell:
+		r.handleTableCell(w, node, entering)
+	case blackfriday.HTMLSpan:
+		// ignore other HTML tags
+	default:
+		fmt.Fprintln(os.Stderr, "WARNING: go-md2man does not handle node type "+node.Type.String())
+	}
+	return walkAction
+}
+
+func (r *roffRenderer) handleHeading(w io.Writer, node *blackfriday.Node, entering bool) {
+	if entering {
+		switch node.Level {
+		case 1:
+			if !r.firstHeader {
+				out(w, titleHeader)
+				r.firstHeader = true
+				break
+			}
+			out(w, topLevelHeader)
+		case 2:
+			out(w, secondLevelHdr)
+		default:
+			out(w, otherHeader)
+		}
+	}
+}
+
+func (r *roffRenderer) handleList(w io.Writer, node *blackfriday.Node, entering bool) {
+	openTag := listTag
+	closeTag := listCloseTag
+	if node.ListFlags&blackfriday.ListTypeDefinition != 0 {
+		// tags for definition lists handled within Item node
+		openTag = ""
+		closeTag = ""
+	}
+	if entering {
+		r.listDepth++
+		if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
+			r.listCounters = append(r.listCounters, 1)
+		}
+		out(w, openTag)
+	} else {
+		if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
+			r.listCounters = r.listCounters[:len(r.listCounters)-1]
+		}
+		out(w, closeTag)
+		r.listDepth--
+	}
+}
+
+func (r *roffRenderer) handleItem(w io.Writer, node *blackfriday.Node, entering bool) {
+	if entering {
+		if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
+			out(w, fmt.Sprintf(".IP \"%3d.\" 5\n", r.listCounters[len(r.listCounters)-1]))
+			r.listCounters[len(r.listCounters)-1]++
+		} else if node.ListFlags&blackfriday.ListTypeTerm != 0 {
+			// DT (definition term): line just before DD (see below).
+			out(w, dtTag)
+			r.firstDD = true
+		} else if node.ListFlags&blackfriday.ListTypeDefinition != 0 {
+			// DD (definition description): line that starts with ": ".
+			//
+			// We have to distinguish between the first DD and the
+			// subsequent ones, as there should be no vertical
+			// whitespace between the DT and the first DD.
+			if r.firstDD {
+				r.firstDD = false
+			} else {
+				out(w, dd2Tag)
+			}
+		} else {
+			out(w, ".IP \\(bu 2\n")
+		}
+	} else {
+		out(w, "\n")
+	}
+}
+
+func (r *roffRenderer) handleTable(w io.Writer, node *blackfriday.Node, entering bool) {
+	if entering {
+		out(w, tableStart)
+		// call walker to count cells (and rows?) so format section can be produced
+		columns := countColumns(node)
+		out(w, strings.Repeat("l ", columns)+"\n")
+		out(w, strings.Repeat("l ", columns)+".\n")
+	} else {
+		out(w, tableEnd)
+	}
+}
+
+func (r *roffRenderer) handleTableCell(w io.Writer, node *blackfriday.Node, entering bool) {
+	if entering {
+		var start string
+		if node.Prev != nil && node.Prev.Type == blackfriday.TableCell {
+			start = "\t"
+		}
+		if node.IsHeader {
+			start += codespanTag
+		} else if nodeLiteralSize(node) > 30 {
+			start += tableCellStart
+		}
+		out(w, start)
+	} else {
+		var end string
+		if node.IsHeader {
+			end = codespanCloseTag
+		} else if nodeLiteralSize(node) > 30 {
+			end = tableCellEnd
+		}
+		if node.Next == nil && end != tableCellEnd {
+			// Last cell: need to carriage return if we are at the end of the
+			// header row and content isn't wrapped in a "tablecell"
+			end += crTag
+		}
+		out(w, end)
+	}
+}
+
+func nodeLiteralSize(node *blackfriday.Node) int {
+	total := 0
+	for n := node.FirstChild; n != nil; n = n.FirstChild {
+		total += len(n.Literal)
+	}
+	return total
+}
+
+// because roff format requires knowing the column count before outputting any table
+// data we need to walk a table tree and count the columns
+func countColumns(node *blackfriday.Node) int {
+	var columns int
+
+	node.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+		switch node.Type {
+		case blackfriday.TableRow:
+			if !entering {
+				return blackfriday.Terminate
+			}
+		case blackfriday.TableCell:
+			if entering {
+				columns++
+			}
+		default:
+		}
+		return blackfriday.GoToNext
+	})
+	return columns
+}
+
+func out(w io.Writer, output string) {
+	io.WriteString(w, output) // nolint: errcheck
+}
+
+func escapeSpecialChars(w io.Writer, text []byte) {
+	for i := 0; i < len(text); i++ {
+		// escape initial apostrophe or period
+		if len(text) >= 1 && (text[0] == '\'' || text[0] == '.') {
+			out(w, "\\&")
+		}
+
+		// directly copy normal characters
+		org := i
+
+		for i < len(text) && text[i] != '\\' {
+			i++
+		}
+		if i > org {
+			w.Write(text[org:i]) // nolint: errcheck
+		}
+
+		// escape a character
+		if i >= len(text) {
+			break
+		}
+
+		w.Write([]byte{'\\', text[i]}) // nolint: errcheck
+	}
+}

vendor/github.com/davecgh/go-spew/LICENSE

@@ -0,0 +1,15 @@
+ISC License
+
+Copyright (c) 2012-2016 Dave Collins <dave@davec.name>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

vendor/github.com/davecgh/go-spew/spew/bypass.go

@@ -0,0 +1,145 @@
+// Copyright (c) 2015-2016 Dave Collins <dave@davec.name>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// NOTE: Due to the following build constraints, this file will only be compiled
+// when the code is not running on Google App Engine, compiled by GopherJS, and
+// "-tags safe" is not added to the go build command line.  The "disableunsafe"
+// tag is deprecated and thus should not be used.
+// Go versions prior to 1.4 are disabled because they use a different layout
+// for interfaces which make the implementation of unsafeReflectValue more complex.
+// +build !js,!appengine,!safe,!disableunsafe,go1.4
+
+package spew
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+const (
+	// UnsafeDisabled is a build-time constant which specifies whether or
+	// not access to the unsafe package is available.
+	UnsafeDisabled = false
+
+	// ptrSize is the size of a pointer on the current arch.
+	ptrSize = unsafe.Sizeof((*byte)(nil))
+)
+
+type flag uintptr
+
+var (
+	// flagRO indicates whether the value field of a reflect.Value
+	// is read-only.
+	flagRO flag
+
+	// flagAddr indicates whether the address of the reflect.Value's
+	// value may be taken.
+	flagAddr flag
+)
+
+// flagKindMask holds the bits that make up the kind
+// part of the flags field. In all the supported versions,
+// it is in the lower 5 bits.
+const flagKindMask = flag(0x1f)
+
+// Different versions of Go have used different
+// bit layouts for the flags type. This table
+// records the known combinations.
+var okFlags = []struct {
+	ro, addr flag
+}{{
+	// From Go 1.4 to 1.5
+	ro:   1 << 5,
+	addr: 1 << 7,
+}, {
+	// Up to Go tip.
+	ro:   1<<5 | 1<<6,
+	addr: 1 << 8,
+}}
+
+var flagValOffset = func() uintptr {
+	field, ok := reflect.TypeOf(reflect.Value{}).FieldByName("flag")
+	if !ok {
+		panic("reflect.Value has no flag field")
+	}
+	return field.Offset
+}()
+
+// flagField returns a pointer to the flag field of a reflect.Value.
+func flagField(v *reflect.Value) *flag {
+	return (*flag)(unsafe.Pointer(uintptr(unsafe.Pointer(v)) + flagValOffset))
+}
+
+// unsafeReflectValue converts the passed reflect.Value into a one that bypasses
+// the typical safety restrictions preventing access to unaddressable and
+// unexported data.  It works by digging the raw pointer to the underlying
+// value out of the protected value and generating a new unprotected (unsafe)
+// reflect.Value to it.
+//
+// This allows us to check for implementations of the Stringer and error
+// interfaces to be used for pretty printing ordinarily unaddressable and
+// inaccessible values such as unexported struct fields.
+func unsafeReflectValue(v reflect.Value) reflect.Value {
+	if !v.IsValid() || (v.CanInterface() && v.CanAddr()) {
+		return v
+	}
+	flagFieldPtr := flagField(&v)
+	*flagFieldPtr &^= flagRO
+	*flagFieldPtr |= flagAddr
+	return v
+}
+
+// Sanity checks against future reflect package changes
+// to the type or semantics of the Value.flag field.
+func init() {
+	field, ok := reflect.TypeOf(reflect.Value{}).FieldByName("flag")
+	if !ok {
+		panic("reflect.Value has no flag field")
+	}
+	if field.Type.Kind() != reflect.TypeOf(flag(0)).Kind() {
+		panic("reflect.Value flag field has changed kind")
+	}
+	type t0 int
+	var t struct {
+		A t0
+		// t0 will have flagEmbedRO set.
+		t0
+		// a will have flagStickyRO set
+		a t0
+	}
+	vA := reflect.ValueOf(t).FieldByName("A")
+	va := reflect.ValueOf(t).FieldByName("a")
+	vt0 := reflect.ValueOf(t).FieldByName("t0")
+
+	// Infer flagRO from the difference between the flags
+	// for the (otherwise identical) fields in t.
+	flagPublic := *flagField(&vA)
+	flagWithRO := *flagField(&va) | *flagField(&vt0)
+	flagRO = flagPublic ^ flagWithRO
+
+	// Infer flagAddr from the difference between a value
+	// taken from a pointer and not.
+	vPtrA := reflect.ValueOf(&t).Elem().FieldByName("A")
+	flagNoPtr := *flagField(&vA)
+	flagPtr := *flagField(&vPtrA)
+	flagAddr = flagNoPtr ^ flagPtr
+
+	// Check that the inferred flags tally with one of the known versions.
+	for _, f := range okFlags {
+		if flagRO == f.ro && flagAddr == f.addr {
+			return
+		}
+	}
+	panic("reflect.Value read-only flag has changed semantics")
+}

vendor/github.com/davecgh/go-spew/spew/bypasssafe.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2015-2016 Dave Collins <dave@davec.name>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// NOTE: Due to the following build constraints, this file will only be compiled
+// when the code is running on Google App Engine, compiled by GopherJS, or
+// "-tags safe" is added to the go build command line.  The "disableunsafe"
+// tag is deprecated and thus should not be used.
+// +build js appengine safe disableunsafe !go1.4
+
+package spew
+
+import "reflect"
+
+const (
+	// UnsafeDisabled is a build-time constant which specifies whether or
+	// not access to the unsafe package is available.
+	UnsafeDisabled = true
+)
+
+// unsafeReflectValue typically converts the passed reflect.Value into a one
+// that bypasses the typical safety restrictions preventing access to
+// unaddressable and unexported data.  However, doing this relies on access to
+// the unsafe package.  This is a stub version which simply returns the passed
+// reflect.Value when the unsafe package is not available.
+func unsafeReflectValue(v reflect.Value) reflect.Value {
+	return v
+}

vendor/github.com/davecgh/go-spew/spew/common.go

@@ -0,0 +1,341 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"reflect"
+	"sort"
+	"strconv"
+)
+
+// Some constants in the form of bytes to avoid string overhead.  This mirrors
+// the technique used in the fmt package.
+var (
+	panicBytes            = []byte("(PANIC=")
+	plusBytes             = []byte("+")
+	iBytes                = []byte("i")
+	trueBytes             = []byte("true")
+	falseBytes            = []byte("false")
+	interfaceBytes        = []byte("(interface {})")
+	commaNewlineBytes     = []byte(",\n")
+	newlineBytes          = []byte("\n")
+	openBraceBytes        = []byte("{")
+	openBraceNewlineBytes = []byte("{\n")
+	closeBraceBytes       = []byte("}")
+	asteriskBytes         = []byte("*")
+	colonBytes            = []byte(":")
+	colonSpaceBytes       = []byte(": ")
+	openParenBytes        = []byte("(")
+	closeParenBytes       = []byte(")")
+	spaceBytes            = []byte(" ")
+	pointerChainBytes     = []byte("->")
+	nilAngleBytes         = []byte("<nil>")
+	maxNewlineBytes       = []byte("<max depth reached>\n")
+	maxShortBytes         = []byte("<max>")
+	circularBytes         = []byte("<already shown>")
+	circularShortBytes    = []byte("<shown>")
+	invalidAngleBytes     = []byte("<invalid>")
+	openBracketBytes      = []byte("[")
+	closeBracketBytes     = []byte("]")
+	percentBytes          = []byte("%")
+	precisionBytes        = []byte(".")
+	openAngleBytes        = []byte("<")
+	closeAngleBytes       = []byte(">")
+	openMapBytes          = []byte("map[")
+	closeMapBytes         = []byte("]")
+	lenEqualsBytes        = []byte("len=")
+	capEqualsBytes        = []byte("cap=")
+)
+
+// hexDigits is used to map a decimal value to a hex digit.
+var hexDigits = "0123456789abcdef"
+
+// catchPanic handles any panics that might occur during the handleMethods
+// calls.
+func catchPanic(w io.Writer, v reflect.Value) {
+	if err := recover(); err != nil {
+		w.Write(panicBytes)
+		fmt.Fprintf(w, "%v", err)
+		w.Write(closeParenBytes)
+	}
+}
+
+// handleMethods attempts to call the Error and String methods on the underlying
+// type the passed reflect.Value represents and outputes the result to Writer w.
+//
+// It handles panics in any called methods by catching and displaying the error
+// as the formatted value.
+func handleMethods(cs *ConfigState, w io.Writer, v reflect.Value) (handled bool) {
+	// We need an interface to check if the type implements the error or
+	// Stringer interface.  However, the reflect package won't give us an
+	// interface on certain things like unexported struct fields in order
+	// to enforce visibility rules.  We use unsafe, when it's available,
+	// to bypass these restrictions since this package does not mutate the
+	// values.
+	if !v.CanInterface() {
+		if UnsafeDisabled {
+			return false
+		}
+
+		v = unsafeReflectValue(v)
+	}
+
+	// Choose whether or not to do error and Stringer interface lookups against
+	// the base type or a pointer to the base type depending on settings.
+	// Technically calling one of these methods with a pointer receiver can
+	// mutate the value, however, types which choose to satisify an error or
+	// Stringer interface with a pointer receiver should not be mutating their
+	// state inside these interface methods.
+	if !cs.DisablePointerMethods && !UnsafeDisabled && !v.CanAddr() {
+		v = unsafeReflectValue(v)
+	}
+	if v.CanAddr() {
+		v = v.Addr()
+	}
+
+	// Is it an error or Stringer?
+	switch iface := v.Interface().(type) {
+	case error:
+		defer catchPanic(w, v)
+		if cs.ContinueOnMethod {
+			w.Write(openParenBytes)
+			w.Write([]byte(iface.Error()))
+			w.Write(closeParenBytes)
+			w.Write(spaceBytes)
+			return false
+		}
+
+		w.Write([]byte(iface.Error()))
+		return true
+
+	case fmt.Stringer:
+		defer catchPanic(w, v)
+		if cs.ContinueOnMethod {
+			w.Write(openParenBytes)
+			w.Write([]byte(iface.String()))
+			w.Write(closeParenBytes)
+			w.Write(spaceBytes)
+			return false
+		}
+		w.Write([]byte(iface.String()))
+		return true
+	}
+	return false
+}
+
+// printBool outputs a boolean value as true or false to Writer w.
+func printBool(w io.Writer, val bool) {
+	if val {
+		w.Write(trueBytes)
+	} else {
+		w.Write(falseBytes)
+	}
+}
+
+// printInt outputs a signed integer value to Writer w.
+func printInt(w io.Writer, val int64, base int) {
+	w.Write([]byte(strconv.FormatInt(val, base)))
+}
+
+// printUint outputs an unsigned integer value to Writer w.
+func printUint(w io.Writer, val uint64, base int) {
+	w.Write([]byte(strconv.FormatUint(val, base)))
+}
+
+// printFloat outputs a floating point value using the specified precision,
+// which is expected to be 32 or 64bit, to Writer w.
+func printFloat(w io.Writer, val float64, precision int) {
+	w.Write([]byte(strconv.FormatFloat(val, 'g', -1, precision)))
+}
+
+// printComplex outputs a complex value using the specified float precision
+// for the real and imaginary parts to Writer w.
+func printComplex(w io.Writer, c complex128, floatPrecision int) {
+	r := real(c)
+	w.Write(openParenBytes)
+	w.Write([]byte(strconv.FormatFloat(r, 'g', -1, floatPrecision)))
+	i := imag(c)
+	if i >= 0 {
+		w.Write(plusBytes)
+	}
+	w.Write([]byte(strconv.FormatFloat(i, 'g', -1, floatPrecision)))
+	w.Write(iBytes)
+	w.Write(closeParenBytes)
+}
+
+// printHexPtr outputs a uintptr formatted as hexadecimal with a leading '0x'
+// prefix to Writer w.
+func printHexPtr(w io.Writer, p uintptr) {
+	// Null pointer.
+	num := uint64(p)
+	if num == 0 {
+		w.Write(nilAngleBytes)
+		return
+	}
+
+	// Max uint64 is 16 bytes in hex + 2 bytes for '0x' prefix
+	buf := make([]byte, 18)
+
+	// It's simpler to construct the hex string right to left.
+	base := uint64(16)
+	i := len(buf) - 1
+	for num >= base {
+		buf[i] = hexDigits[num%base]
+		num /= base
+		i--
+	}
+	buf[i] = hexDigits[num]
+
+	// Add '0x' prefix.
+	i--
+	buf[i] = 'x'
+	i--
+	buf[i] = '0'
+
+	// Strip unused leading bytes.
+	buf = buf[i:]
+	w.Write(buf)
+}
+
+// valuesSorter implements sort.Interface to allow a slice of reflect.Value
+// elements to be sorted.
+type valuesSorter struct {
+	values  []reflect.Value
+	strings []string // either nil or same len and values
+	cs      *ConfigState
+}
+
+// newValuesSorter initializes a valuesSorter instance, which holds a set of
+// surrogate keys on which the data should be sorted.  It uses flags in
+// ConfigState to decide if and how to populate those surrogate keys.
+func newValuesSorter(values []reflect.Value, cs *ConfigState) sort.Interface {
+	vs := &valuesSorter{values: values, cs: cs}
+	if canSortSimply(vs.values[0].Kind()) {
+		return vs
+	}
+	if !cs.DisableMethods {
+		vs.strings = make([]string, len(values))
+		for i := range vs.values {
+			b := bytes.Buffer{}
+			if !handleMethods(cs, &b, vs.values[i]) {
+				vs.strings = nil
+				break
+			}
+			vs.strings[i] = b.String()
+		}
+	}
+	if vs.strings == nil && cs.SpewKeys {
+		vs.strings = make([]string, len(values))
+		for i := range vs.values {
+			vs.strings[i] = Sprintf("%#v", vs.values[i].Interface())
+		}
+	}
+	return vs
+}
+
+// canSortSimply tests whether a reflect.Kind is a primitive that can be sorted
+// directly, or whether it should be considered for sorting by surrogate keys
+// (if the ConfigState allows it).
+func canSortSimply(kind reflect.Kind) bool {
+	// This switch parallels valueSortLess, except for the default case.
+	switch kind {
+	case reflect.Bool:
+		return true
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		return true
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		return true
+	case reflect.Float32, reflect.Float64:
+		return true
+	case reflect.String:
+		return true
+	case reflect.Uintptr:
+		return true
+	case reflect.Array:
+		return true
+	}
+	return false
+}
+
+// Len returns the number of values in the slice.  It is part of the
+// sort.Interface implementation.
+func (s *valuesSorter) Len() int {
+	return len(s.values)
+}
+
+// Swap swaps the values at the passed indices.  It is part of the
+// sort.Interface implementation.
+func (s *valuesSorter) Swap(i, j int) {
+	s.values[i], s.values[j] = s.values[j], s.values[i]
+	if s.strings != nil {
+		s.strings[i], s.strings[j] = s.strings[j], s.strings[i]
+	}
+}
+
+// valueSortLess returns whether the first value should sort before the second
+// value.  It is used by valueSorter.Less as part of the sort.Interface
+// implementation.
+func valueSortLess(a, b reflect.Value) bool {
+	switch a.Kind() {
+	case reflect.Bool:
+		return !a.Bool() && b.Bool()
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		return a.Int() < b.Int()
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		return a.Uint() < b.Uint()
+	case reflect.Float32, reflect.Float64:
+		return a.Float() < b.Float()
+	case reflect.String:
+		return a.String() < b.String()
+	case reflect.Uintptr:
+		return a.Uint() < b.Uint()
+	case reflect.Array:
+		// Compare the contents of both arrays.
+		l := a.Len()
+		for i := 0; i < l; i++ {
+			av := a.Index(i)
+			bv := b.Index(i)
+			if av.Interface() == bv.Interface() {
+				continue
+			}
+			return valueSortLess(av, bv)
+		}
+	}
+	return a.String() < b.String()
+}
+
+// Less returns whether the value at index i should sort before the
+// value at index j.  It is part of the sort.Interface implementation.
+func (s *valuesSorter) Less(i, j int) bool {
+	if s.strings == nil {
+		return valueSortLess(s.values[i], s.values[j])
+	}
+	return s.strings[i] < s.strings[j]
+}
+
+// sortValues is a sort function that handles both native types and any type that
+// can be converted to error or Stringer.  Other inputs are sorted according to
+// their Value.String() value to ensure display stability.
+func sortValues(values []reflect.Value, cs *ConfigState) {
+	if len(values) == 0 {
+		return
+	}
+	sort.Sort(newValuesSorter(values, cs))
+}

vendor/github.com/davecgh/go-spew/spew/config.go

@@ -0,0 +1,306 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+)
+
+// ConfigState houses the configuration options used by spew to format and
+// display values.  There is a global instance, Config, that is used to control
+// all top-level Formatter and Dump functionality.  Each ConfigState instance
+// provides methods equivalent to the top-level functions.
+//
+// The zero value for ConfigState provides no indentation.  You would typically
+// want to set it to a space or a tab.
+//
+// Alternatively, you can use NewDefaultConfig to get a ConfigState instance
+// with default settings.  See the documentation of NewDefaultConfig for default
+// values.
+type ConfigState struct {
+	// Indent specifies the string to use for each indentation level.  The
+	// global config instance that all top-level functions use set this to a
+	// single space by default.  If you would like more indentation, you might
+	// set this to a tab with "\t" or perhaps two spaces with "  ".
+	Indent string
+
+	// MaxDepth controls the maximum number of levels to descend into nested
+	// data structures.  The default, 0, means there is no limit.
+	//
+	// NOTE: Circular data structures are properly detected, so it is not
+	// necessary to set this value unless you specifically want to limit deeply
+	// nested data structures.
+	MaxDepth int
+
+	// DisableMethods specifies whether or not error and Stringer interfaces are
+	// invoked for types that implement them.
+	DisableMethods bool
+
+	// DisablePointerMethods specifies whether or not to check for and invoke
+	// error and Stringer interfaces on types which only accept a pointer
+	// receiver when the current type is not a pointer.
+	//
+	// NOTE: This might be an unsafe action since calling one of these methods
+	// with a pointer receiver could technically mutate the value, however,
+	// in practice, types which choose to satisify an error or Stringer
+	// interface with a pointer receiver should not be mutating their state
+	// inside these interface methods.  As a result, this option relies on
+	// access to the unsafe package, so it will not have any effect when
+	// running in environments without access to the unsafe package such as
+	// Google App Engine or with the "safe" build tag specified.
+	DisablePointerMethods bool
+
+	// DisablePointerAddresses specifies whether to disable the printing of
+	// pointer addresses. This is useful when diffing data structures in tests.
+	DisablePointerAddresses bool
+
+	// DisableCapacities specifies whether to disable the printing of capacities
+	// for arrays, slices, maps and channels. This is useful when diffing
+	// data structures in tests.
+	DisableCapacities bool
+
+	// ContinueOnMethod specifies whether or not recursion should continue once
+	// a custom error or Stringer interface is invoked.  The default, false,
+	// means it will print the results of invoking the custom error or Stringer
+	// interface and return immediately instead of continuing to recurse into
+	// the internals of the data type.
+	//
+	// NOTE: This flag does not have any effect if method invocation is disabled
+	// via the DisableMethods or DisablePointerMethods options.
+	ContinueOnMethod bool
+
+	// SortKeys specifies map keys should be sorted before being printed. Use
+	// this to have a more deterministic, diffable output.  Note that only
+	// native types (bool, int, uint, floats, uintptr and string) and types
+	// that support the error or Stringer interfaces (if methods are
+	// enabled) are supported, with other types sorted according to the
+	// reflect.Value.String() output which guarantees display stability.
+	SortKeys bool
+
+	// SpewKeys specifies that, as a last resort attempt, map keys should
+	// be spewed to strings and sorted by those strings.  This is only
+	// considered if SortKeys is true.
+	SpewKeys bool
+}
+
+// Config is the active configuration of the top-level functions.
+// The configuration can be changed by modifying the contents of spew.Config.
+var Config = ConfigState{Indent: " "}
+
+// Errorf is a wrapper for fmt.Errorf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the formatted string as a value that satisfies error.  See NewFormatter
+// for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Errorf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Errorf(format string, a ...interface{}) (err error) {
+	return fmt.Errorf(format, c.convertArgs(a)...)
+}
+
+// Fprint is a wrapper for fmt.Fprint that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprint(w, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprint(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprint(w, c.convertArgs(a)...)
+}
+
+// Fprintf is a wrapper for fmt.Fprintf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintf(w, format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error) {
+	return fmt.Fprintf(w, format, c.convertArgs(a)...)
+}
+
+// Fprintln is a wrapper for fmt.Fprintln that treats each argument as if it
+// passed with a Formatter interface returned by c.NewFormatter.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintln(w, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprintln(w, c.convertArgs(a)...)
+}
+
+// Print is a wrapper for fmt.Print that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Print(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Print(a ...interface{}) (n int, err error) {
+	return fmt.Print(c.convertArgs(a)...)
+}
+
+// Printf is a wrapper for fmt.Printf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Printf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Printf(format string, a ...interface{}) (n int, err error) {
+	return fmt.Printf(format, c.convertArgs(a)...)
+}
+
+// Println is a wrapper for fmt.Println that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Println(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Println(a ...interface{}) (n int, err error) {
+	return fmt.Println(c.convertArgs(a)...)
+}
+
+// Sprint is a wrapper for fmt.Sprint that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprint(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprint(a ...interface{}) string {
+	return fmt.Sprint(c.convertArgs(a)...)
+}
+
+// Sprintf is a wrapper for fmt.Sprintf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprintf(format string, a ...interface{}) string {
+	return fmt.Sprintf(format, c.convertArgs(a)...)
+}
+
+// Sprintln is a wrapper for fmt.Sprintln that treats each argument as if it
+// were passed with a Formatter interface returned by c.NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintln(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprintln(a ...interface{}) string {
+	return fmt.Sprintln(c.convertArgs(a)...)
+}
+
+/*
+NewFormatter returns a custom formatter that satisfies the fmt.Formatter
+interface.  As a result, it integrates cleanly with standard fmt package
+printing functions.  The formatter is useful for inline printing of smaller data
+types similar to the standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), and %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Typically this function shouldn't be called directly.  It is much easier to make
+use of the custom formatter by calling one of the convenience functions such as
+c.Printf, c.Println, or c.Printf.
+*/
+func (c *ConfigState) NewFormatter(v interface{}) fmt.Formatter {
+	return newFormatter(c, v)
+}
+
+// Fdump formats and displays the passed arguments to io.Writer w.  It formats
+// exactly the same as Dump.
+func (c *ConfigState) Fdump(w io.Writer, a ...interface{}) {
+	fdump(c, w, a...)
+}
+
+/*
+Dump displays the passed parameters to standard out with newlines, customizable
+indentation, and additional debug information such as complete types and all
+pointer addresses used to indirect to the final value.  It provides the
+following features over the built-in printing facilities provided by the fmt
+package:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output
+
+The configuration options are controlled by modifying the public members
+of c.  See ConfigState for options documentation.
+
+See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to
+get the formatted result as a string.
+*/
+func (c *ConfigState) Dump(a ...interface{}) {
+	fdump(c, os.Stdout, a...)
+}
+
+// Sdump returns a string with the passed arguments formatted exactly the same
+// as Dump.
+func (c *ConfigState) Sdump(a ...interface{}) string {
+	var buf bytes.Buffer
+	fdump(c, &buf, a...)
+	return buf.String()
+}
+
+// convertArgs accepts a slice of arguments and returns a slice of the same
+// length with each argument converted to a spew Formatter interface using
+// the ConfigState associated with s.
+func (c *ConfigState) convertArgs(args []interface{}) (formatters []interface{}) {
+	formatters = make([]interface{}, len(args))
+	for index, arg := range args {
+		formatters[index] = newFormatter(c, arg)
+	}
+	return formatters
+}
+
+// NewDefaultConfig returns a ConfigState with the following default settings.
+//
+// 	Indent: " "
+// 	MaxDepth: 0
+// 	DisableMethods: false
+// 	DisablePointerMethods: false
+// 	ContinueOnMethod: false
+// 	SortKeys: false
+func NewDefaultConfig() *ConfigState {
+	return &ConfigState{Indent: " "}
+}

vendor/github.com/davecgh/go-spew/spew/doc.go

@@ -0,0 +1,211 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+Package spew implements a deep pretty printer for Go data structures to aid in
+debugging.
+
+A quick overview of the additional features spew provides over the built-in
+printing facilities for Go data types are as follows:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output (only when using
+	  Dump style)
+
+There are two different approaches spew allows for dumping Go data structures:
+
+	* Dump style which prints with newlines, customizable indentation,
+	  and additional debug information such as types and all pointer addresses
+	  used to indirect to the final value
+	* A custom Formatter interface that integrates cleanly with the standard fmt
+	  package and replaces %v, %+v, %#v, and %#+v to provide inline printing
+	  similar to the default %v while providing the additional functionality
+	  outlined above and passing unsupported format verbs such as %x and %q
+	  along to fmt
+
+Quick Start
+
+This section demonstrates how to quickly get started with spew.  See the
+sections below for further details on formatting and configuration options.
+
+To dump a variable with full newlines, indentation, type, and pointer
+information use Dump, Fdump, or Sdump:
+	spew.Dump(myVar1, myVar2, ...)
+	spew.Fdump(someWriter, myVar1, myVar2, ...)
+	str := spew.Sdump(myVar1, myVar2, ...)
+
+Alternatively, if you would prefer to use format strings with a compacted inline
+printing style, use the convenience wrappers Printf, Fprintf, etc with
+%v (most compact), %+v (adds pointer addresses), %#v (adds types), or
+%#+v (adds types and pointer addresses):
+	spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+	spew.Fprintf(someWriter, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Fprintf(someWriter, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+
+Configuration Options
+
+Configuration of spew is handled by fields in the ConfigState type.  For
+convenience, all of the top-level functions use a global state available
+via the spew.Config global.
+
+It is also possible to create a ConfigState instance that provides methods
+equivalent to the top-level functions.  This allows concurrent configuration
+options.  See the ConfigState documentation for more details.
+
+The following configuration options are available:
+	* Indent
+		String to use for each indentation level for Dump functions.
+		It is a single space by default.  A popular alternative is "\t".
+
+	* MaxDepth
+		Maximum number of levels to descend into nested data structures.
+		There is no limit by default.
+
+	* DisableMethods
+		Disables invocation of error and Stringer interface methods.
+		Method invocation is enabled by default.
+
+	* DisablePointerMethods
+		Disables invocation of error and Stringer interface methods on types
+		which only accept pointer receivers from non-pointer variables.
+		Pointer method invocation is enabled by default.
+
+	* DisablePointerAddresses
+		DisablePointerAddresses specifies whether to disable the printing of
+		pointer addresses. This is useful when diffing data structures in tests.
+
+	* DisableCapacities
+		DisableCapacities specifies whether to disable the printing of
+		capacities for arrays, slices, maps and channels. This is useful when
+		diffing data structures in tests.
+
+	* ContinueOnMethod
+		Enables recursion into types after invoking error and Stringer interface
+		methods. Recursion after method invocation is disabled by default.
+
+	* SortKeys
+		Specifies map keys should be sorted before being printed. Use
+		this to have a more deterministic, diffable output.  Note that
+		only native types (bool, int, uint, floats, uintptr and string)
+		and types which implement error or Stringer interfaces are
+		supported with other types sorted according to the
+		reflect.Value.String() output which guarantees display
+		stability.  Natural map order is used by default.
+
+	* SpewKeys
+		Specifies that, as a last resort attempt, map keys should be
+		spewed to strings and sorted by those strings.  This is only
+		considered if SortKeys is true.
+
+Dump Usage
+
+Simply call spew.Dump with a list of variables you want to dump:
+
+	spew.Dump(myVar1, myVar2, ...)
+
+You may also call spew.Fdump if you would prefer to output to an arbitrary
+io.Writer.  For example, to dump to standard error:
+
+	spew.Fdump(os.Stderr, myVar1, myVar2, ...)
+
+A third option is to call spew.Sdump to get the formatted output as a string:
+
+	str := spew.Sdump(myVar1, myVar2, ...)
+
+Sample Dump Output
+
+See the Dump example for details on the setup of the types and variables being
+shown here.
+
+	(main.Foo) {
+	 unexportedField: (*main.Bar)(0xf84002e210)({
+	  flag: (main.Flag) flagTwo,
+	  data: (uintptr) <nil>
+	 }),
+	 ExportedField: (map[interface {}]interface {}) (len=1) {
+	  (string) (len=3) "one": (bool) true
+	 }
+	}
+
+Byte (and uint8) arrays and slices are displayed uniquely like the hexdump -C
+command as shown.
+	([]uint8) (len=32 cap=32) {
+	 00000000  11 12 13 14 15 16 17 18  19 1a 1b 1c 1d 1e 1f 20  |............... |
+	 00000010  21 22 23 24 25 26 27 28  29 2a 2b 2c 2d 2e 2f 30  |!"#$%&'()*+,-./0|
+	 00000020  31 32                                             |12|
+	}
+
+Custom Formatter
+
+Spew provides a custom formatter that implements the fmt.Formatter interface
+so that it integrates cleanly with standard fmt package printing functions. The
+formatter is useful for inline printing of smaller data types similar to the
+standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Custom Formatter Usage
+
+The simplest way to make use of the spew custom formatter is to call one of the
+convenience functions such as spew.Printf, spew.Println, or spew.Printf.  The
+functions have syntax you are most likely already familiar with:
+
+	spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+	spew.Println(myVar, myVar2)
+	spew.Fprintf(os.Stderr, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Fprintf(os.Stderr, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+
+See the Index for the full list convenience functions.
+
+Sample Formatter Output
+
+Double pointer to a uint8:
+	  %v: <**>5
+	 %+v: <**>(0xf8400420d0->0xf8400420c8)5
+	 %#v: (**uint8)5
+	%#+v: (**uint8)(0xf8400420d0->0xf8400420c8)5
+
+Pointer to circular struct with a uint8 field and a pointer to itself:
+	  %v: <*>{1 <*><shown>}
+	 %+v: <*>(0xf84003e260){ui8:1 c:<*>(0xf84003e260)<shown>}
+	 %#v: (*main.circular){ui8:(uint8)1 c:(*main.circular)<shown>}
+	%#+v: (*main.circular)(0xf84003e260){ui8:(uint8)1 c:(*main.circular)(0xf84003e260)<shown>}
+
+See the Printf example for details on the setup of variables being shown
+here.
+
+Errors
+
+Since it is possible for custom Stringer/error interfaces to panic, spew
+detects them and handles them internally by printing the panic information
+inline with the output.  Since spew is intended to provide deep pretty printing
+capabilities on structures, it intentionally does not return any errors.
+*/
+package spew

vendor/github.com/davecgh/go-spew/spew/dump.go

@@ -0,0 +1,509 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	// uint8Type is a reflect.Type representing a uint8.  It is used to
+	// convert cgo types to uint8 slices for hexdumping.
+	uint8Type = reflect.TypeOf(uint8(0))
+
+	// cCharRE is a regular expression that matches a cgo char.
+	// It is used to detect character arrays to hexdump them.
+	cCharRE = regexp.MustCompile(`^.*\._Ctype_char$`)
+
+	// cUnsignedCharRE is a regular expression that matches a cgo unsigned
+	// char.  It is used to detect unsigned character arrays to hexdump
+	// them.
+	cUnsignedCharRE = regexp.MustCompile(`^.*\._Ctype_unsignedchar$`)
+
+	// cUint8tCharRE is a regular expression that matches a cgo uint8_t.
+	// It is used to detect uint8_t arrays to hexdump them.
+	cUint8tCharRE = regexp.MustCompile(`^.*\._Ctype_uint8_t$`)
+)
+
+// dumpState contains information about the state of a dump operation.
+type dumpState struct {
+	w                io.Writer
+	depth            int
+	pointers         map[uintptr]int
+	ignoreNextType   bool
+	ignoreNextIndent bool
+	cs               *ConfigState
+}
+
+// indent performs indentation according to the depth level and cs.Indent
+// option.
+func (d *dumpState) indent() {
+	if d.ignoreNextIndent {
+		d.ignoreNextIndent = false
+		return
+	}
+	d.w.Write(bytes.Repeat([]byte(d.cs.Indent), d.depth))
+}
+
+// unpackValue returns values inside of non-nil interfaces when possible.
+// This is useful for data types like structs, arrays, slices, and maps which
+// can contain varying types packed inside an interface.
+func (d *dumpState) unpackValue(v reflect.Value) reflect.Value {
+	if v.Kind() == reflect.Interface && !v.IsNil() {
+		v = v.Elem()
+	}
+	return v
+}
+
+// dumpPtr handles formatting of pointers by indirecting them as necessary.
+func (d *dumpState) dumpPtr(v reflect.Value) {
+	// Remove pointers at or below the current depth from map used to detect
+	// circular refs.
+	for k, depth := range d.pointers {
+		if depth >= d.depth {
+			delete(d.pointers, k)
+		}
+	}
+
+	// Keep list of all dereferenced pointers to show later.
+	pointerChain := make([]uintptr, 0)
+
+	// Figure out how many levels of indirection there are by dereferencing
+	// pointers and unpacking interfaces down the chain while detecting circular
+	// references.
+	nilFound := false
+	cycleFound := false
+	indirects := 0
+	ve := v
+	for ve.Kind() == reflect.Ptr {
+		if ve.IsNil() {
+			nilFound = true
+			break
+		}
+		indirects++
+		addr := ve.Pointer()
+		pointerChain = append(pointerChain, addr)
+		if pd, ok := d.pointers[addr]; ok && pd < d.depth {
+			cycleFound = true
+			indirects--
+			break
+		}
+		d.pointers[addr] = d.depth
+
+		ve = ve.Elem()
+		if ve.Kind() == reflect.Interface {
+			if ve.IsNil() {
+				nilFound = true
+				break
+			}
+			ve = ve.Elem()
+		}
+	}
+
+	// Display type information.
+	d.w.Write(openParenBytes)
+	d.w.Write(bytes.Repeat(asteriskBytes, indirects))
+	d.w.Write([]byte(ve.Type().String()))
+	d.w.Write(closeParenBytes)
+
+	// Display pointer information.
+	if !d.cs.DisablePointerAddresses && len(pointerChain) > 0 {
+		d.w.Write(openParenBytes)
+		for i, addr := range pointerChain {
+			if i > 0 {
+				d.w.Write(pointerChainBytes)
+			}
+			printHexPtr(d.w, addr)
+		}
+		d.w.Write(closeParenBytes)
+	}
+
+	// Display dereferenced value.
+	d.w.Write(openParenBytes)
+	switch {
+	case nilFound:
+		d.w.Write(nilAngleBytes)
+
+	case cycleFound:
+		d.w.Write(circularBytes)
+
+	default:
+		d.ignoreNextType = true
+		d.dump(ve)
+	}
+	d.w.Write(closeParenBytes)
+}
+
+// dumpSlice handles formatting of arrays and slices.  Byte (uint8 under
+// reflection) arrays and slices are dumped in hexdump -C fashion.
+func (d *dumpState) dumpSlice(v reflect.Value) {
+	// Determine whether this type should be hex dumped or not.  Also,
+	// for types which should be hexdumped, try to use the underlying data
+	// first, then fall back to trying to convert them to a uint8 slice.
+	var buf []uint8
+	doConvert := false
+	doHexDump := false
+	numEntries := v.Len()
+	if numEntries > 0 {
+		vt := v.Index(0).Type()
+		vts := vt.String()
+		switch {
+		// C types that need to be converted.
+		case cCharRE.MatchString(vts):
+			fallthrough
+		case cUnsignedCharRE.MatchString(vts):
+			fallthrough
+		case cUint8tCharRE.MatchString(vts):
+			doConvert = true
+
+		// Try to use existing uint8 slices and fall back to converting
+		// and copying if that fails.
+		case vt.Kind() == reflect.Uint8:
+			// We need an addressable interface to convert the type
+			// to a byte slice.  However, the reflect package won't
+			// give us an interface on certain things like
+			// unexported struct fields in order to enforce
+			// visibility rules.  We use unsafe, when available, to
+			// bypass these restrictions since this package does not
+			// mutate the values.
+			vs := v
+			if !vs.CanInterface() || !vs.CanAddr() {
+				vs = unsafeReflectValue(vs)
+			}
+			if !UnsafeDisabled {
+				vs = vs.Slice(0, numEntries)
+
+				// Use the existing uint8 slice if it can be
+				// type asserted.
+				iface := vs.Interface()
+				if slice, ok := iface.([]uint8); ok {
+					buf = slice
+					doHexDump = true
+					break
+				}
+			}
+
+			// The underlying data needs to be converted if it can't
+			// be type asserted to a uint8 slice.
+			doConvert = true
+		}
+
+		// Copy and convert the underlying type if needed.
+		if doConvert && vt.ConvertibleTo(uint8Type) {
+			// Convert and copy each element into a uint8 byte
+			// slice.
+			buf = make([]uint8, numEntries)
+			for i := 0; i < numEntries; i++ {
+				vv := v.Index(i)
+				buf[i] = uint8(vv.Convert(uint8Type).Uint())
+			}
+			doHexDump = true
+		}
+	}
+
+	// Hexdump the entire slice as needed.
+	if doHexDump {
+		indent := strings.Repeat(d.cs.Indent, d.depth)
+		str := indent + hex.Dump(buf)
+		str = strings.Replace(str, "\n", "\n"+indent, -1)
+		str = strings.TrimRight(str, d.cs.Indent)
+		d.w.Write([]byte(str))
+		return
+	}
+
+	// Recursively call dump for each item.
+	for i := 0; i < numEntries; i++ {
+		d.dump(d.unpackValue(v.Index(i)))
+		if i < (numEntries - 1) {
+			d.w.Write(commaNewlineBytes)
+		} else {
+			d.w.Write(newlineBytes)
+		}
+	}
+}
+
+// dump is the main workhorse for dumping a value.  It uses the passed reflect
+// value to figure out what kind of object we are dealing with and formats it
+// appropriately.  It is a recursive function, however circular data structures
+// are detected and handled properly.
+func (d *dumpState) dump(v reflect.Value) {
+	// Handle invalid reflect values immediately.
+	kind := v.Kind()
+	if kind == reflect.Invalid {
+		d.w.Write(invalidAngleBytes)
+		return
+	}
+
+	// Handle pointers specially.
+	if kind == reflect.Ptr {
+		d.indent()
+		d.dumpPtr(v)
+		return
+	}
+
+	// Print type information unless already handled elsewhere.
+	if !d.ignoreNextType {
+		d.indent()
+		d.w.Write(openParenBytes)
+		d.w.Write([]byte(v.Type().String()))
+		d.w.Write(closeParenBytes)
+		d.w.Write(spaceBytes)
+	}
+	d.ignoreNextType = false
+
+	// Display length and capacity if the built-in len and cap functions
+	// work with the value's kind and the len/cap itself is non-zero.
+	valueLen, valueCap := 0, 0
+	switch v.Kind() {
+	case reflect.Array, reflect.Slice, reflect.Chan:
+		valueLen, valueCap = v.Len(), v.Cap()
+	case reflect.Map, reflect.String:
+		valueLen = v.Len()
+	}
+	if valueLen != 0 || !d.cs.DisableCapacities && valueCap != 0 {
+		d.w.Write(openParenBytes)
+		if valueLen != 0 {
+			d.w.Write(lenEqualsBytes)
+			printInt(d.w, int64(valueLen), 10)
+		}
+		if !d.cs.DisableCapacities && valueCap != 0 {
+			if valueLen != 0 {
+				d.w.Write(spaceBytes)
+			}
+			d.w.Write(capEqualsBytes)
+			printInt(d.w, int64(valueCap), 10)
+		}
+		d.w.Write(closeParenBytes)
+		d.w.Write(spaceBytes)
+	}
+
+	// Call Stringer/error interfaces if they exist and the handle methods flag
+	// is enabled
+	if !d.cs.DisableMethods {
+		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
+			if handled := handleMethods(d.cs, d.w, v); handled {
+				return
+			}
+		}
+	}
+
+	switch kind {
+	case reflect.Invalid:
+		// Do nothing.  We should never get here since invalid has already
+		// been handled above.
+
+	case reflect.Bool:
+		printBool(d.w, v.Bool())
+
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		printInt(d.w, v.Int(), 10)
+
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		printUint(d.w, v.Uint(), 10)
+
+	case reflect.Float32:
+		printFloat(d.w, v.Float(), 32)
+
+	case reflect.Float64:
+		printFloat(d.w, v.Float(), 64)
+
+	case reflect.Complex64:
+		printComplex(d.w, v.Complex(), 32)
+
+	case reflect.Complex128:
+		printComplex(d.w, v.Complex(), 64)
+
+	case reflect.Slice:
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+			break
+		}
+		fallthrough
+
+	case reflect.Array:
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			d.dumpSlice(v)
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.String:
+		d.w.Write([]byte(strconv.Quote(v.String())))
+
+	case reflect.Interface:
+		// The only time we should get here is for nil interfaces due to
+		// unpackValue calls.
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+		}
+
+	case reflect.Ptr:
+		// Do nothing.  We should never get here since pointers have already
+		// been handled above.
+
+	case reflect.Map:
+		// nil maps should be indicated as different than empty maps
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+			break
+		}
+
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			numEntries := v.Len()
+			keys := v.MapKeys()
+			if d.cs.SortKeys {
+				sortValues(keys, d.cs)
+			}
+			for i, key := range keys {
+				d.dump(d.unpackValue(key))
+				d.w.Write(colonSpaceBytes)
+				d.ignoreNextIndent = true
+				d.dump(d.unpackValue(v.MapIndex(key)))
+				if i < (numEntries - 1) {
+					d.w.Write(commaNewlineBytes)
+				} else {
+					d.w.Write(newlineBytes)
+				}
+			}
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.Struct:
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			vt := v.Type()
+			numFields := v.NumField()
+			for i := 0; i < numFields; i++ {
+				d.indent()
+				vtf := vt.Field(i)
+				d.w.Write([]byte(vtf.Name))
+				d.w.Write(colonSpaceBytes)
+				d.ignoreNextIndent = true
+				d.dump(d.unpackValue(v.Field(i)))
+				if i < (numFields - 1) {
+					d.w.Write(commaNewlineBytes)
+				} else {
+					d.w.Write(newlineBytes)
+				}
+			}
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.Uintptr:
+		printHexPtr(d.w, uintptr(v.Uint()))
+
+	case reflect.UnsafePointer, reflect.Chan, reflect.Func:
+		printHexPtr(d.w, v.Pointer())
+
+	// There were not any other types at the time this code was written, but
+	// fall back to letting the default fmt package handle it in case any new
+	// types are added.
+	default:
+		if v.CanInterface() {
+			fmt.Fprintf(d.w, "%v", v.Interface())
+		} else {
+			fmt.Fprintf(d.w, "%v", v.String())
+		}
+	}
+}
+
+// fdump is a helper function to consolidate the logic from the various public
+// methods which take varying writers and config states.
+func fdump(cs *ConfigState, w io.Writer, a ...interface{}) {
+	for _, arg := range a {
+		if arg == nil {
+			w.Write(interfaceBytes)
+			w.Write(spaceBytes)
+			w.Write(nilAngleBytes)
+			w.Write(newlineBytes)
+			continue
+		}
+
+		d := dumpState{w: w, cs: cs}
+		d.pointers = make(map[uintptr]int)
+		d.dump(reflect.ValueOf(arg))
+		d.w.Write(newlineBytes)
+	}
+}
+
+// Fdump formats and displays the passed arguments to io.Writer w.  It formats
+// exactly the same as Dump.
+func Fdump(w io.Writer, a ...interface{}) {
+	fdump(&Config, w, a...)
+}
+
+// Sdump returns a string with the passed arguments formatted exactly the same
+// as Dump.
+func Sdump(a ...interface{}) string {
+	var buf bytes.Buffer
+	fdump(&Config, &buf, a...)
+	return buf.String()
+}
+
+/*
+Dump displays the passed parameters to standard out with newlines, customizable
+indentation, and additional debug information such as complete types and all
+pointer addresses used to indirect to the final value.  It provides the
+following features over the built-in printing facilities provided by the fmt
+package:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output
+
+The configuration options are controlled by an exported package global,
+spew.Config.  See ConfigState for options documentation.
+
+See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to
+get the formatted result as a string.
+*/
+func Dump(a ...interface{}) {
+	fdump(&Config, os.Stdout, a...)
+}

vendor/github.com/davecgh/go-spew/spew/format.go

@@ -0,0 +1,419 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// supportedFlags is a list of all the character flags supported by fmt package.
+const supportedFlags = "0-+# "
+
+// formatState implements the fmt.Formatter interface and contains information
+// about the state of a formatting operation.  The NewFormatter function can
+// be used to get a new Formatter which can be used directly as arguments
+// in standard fmt package printing calls.
+type formatState struct {
+	value          interface{}
+	fs             fmt.State
+	depth          int
+	pointers       map[uintptr]int
+	ignoreNextType bool
+	cs             *ConfigState
+}
+
+// buildDefaultFormat recreates the original format string without precision
+// and width information to pass in to fmt.Sprintf in the case of an
+// unrecognized type.  Unless new types are added to the language, this
+// function won't ever be called.
+func (f *formatState) buildDefaultFormat() (format string) {
+	buf := bytes.NewBuffer(percentBytes)
+
+	for _, flag := range supportedFlags {
+		if f.fs.Flag(int(flag)) {
+			buf.WriteRune(flag)
+		}
+	}
+
+	buf.WriteRune('v')
+
+	format = buf.String()
+	return format
+}
+
+// constructOrigFormat recreates the original format string including precision
+// and width information to pass along to the standard fmt package.  This allows
+// automatic deferral of all format strings this package doesn't support.
+func (f *formatState) constructOrigFormat(verb rune) (format string) {
+	buf := bytes.NewBuffer(percentBytes)
+
+	for _, flag := range supportedFlags {
+		if f.fs.Flag(int(flag)) {
+			buf.WriteRune(flag)
+		}
+	}
+
+	if width, ok := f.fs.Width(); ok {
+		buf.WriteString(strconv.Itoa(width))
+	}
+
+	if precision, ok := f.fs.Precision(); ok {
+		buf.Write(precisionBytes)
+		buf.WriteString(strconv.Itoa(precision))
+	}
+
+	buf.WriteRune(verb)
+
+	format = buf.String()
+	return format
+}
+
+// unpackValue returns values inside of non-nil interfaces when possible and
+// ensures that types for values which have been unpacked from an interface
+// are displayed when the show types flag is also set.
+// This is useful for data types like structs, arrays, slices, and maps which
+// can contain varying types packed inside an interface.
+func (f *formatState) unpackValue(v reflect.Value) reflect.Value {
+	if v.Kind() == reflect.Interface {
+		f.ignoreNextType = false
+		if !v.IsNil() {
+			v = v.Elem()
+		}
+	}
+	return v
+}
+
+// formatPtr handles formatting of pointers by indirecting them as necessary.
+func (f *formatState) formatPtr(v reflect.Value) {
+	// Display nil if top level pointer is nil.
+	showTypes := f.fs.Flag('#')
+	if v.IsNil() && (!showTypes || f.ignoreNextType) {
+		f.fs.Write(nilAngleBytes)
+		return
+	}
+
+	// Remove pointers at or below the current depth from map used to detect
+	// circular refs.
+	for k, depth := range f.pointers {
+		if depth >= f.depth {
+			delete(f.pointers, k)
+		}
+	}
+
+	// Keep list of all dereferenced pointers to possibly show later.
+	pointerChain := make([]uintptr, 0)
+
+	// Figure out how many levels of indirection there are by derferencing
+	// pointers and unpacking interfaces down the chain while detecting circular
+	// references.
+	nilFound := false
+	cycleFound := false
+	indirects := 0
+	ve := v
+	for ve.Kind() == reflect.Ptr {
+		if ve.IsNil() {
+			nilFound = true
+			break
+		}
+		indirects++
+		addr := ve.Pointer()
+		pointerChain = append(pointerChain, addr)
+		if pd, ok := f.pointers[addr]; ok && pd < f.depth {
+			cycleFound = true
+			indirects--
+			break
+		}
+		f.pointers[addr] = f.depth
+
+		ve = ve.Elem()
+		if ve.Kind() == reflect.Interface {
+			if ve.IsNil() {
+				nilFound = true
+				break
+			}
+			ve = ve.Elem()
+		}
+	}
+
+	// Display type or indirection level depending on flags.
+	if showTypes && !f.ignoreNextType {
+		f.fs.Write(openParenBytes)
+		f.fs.Write(bytes.Repeat(asteriskBytes, indirects))
+		f.fs.Write([]byte(ve.Type().String()))
+		f.fs.Write(closeParenBytes)
+	} else {
+		if nilFound || cycleFound {
+			indirects += strings.Count(ve.Type().String(), "*")
+		}
+		f.fs.Write(openAngleBytes)
+		f.fs.Write([]byte(strings.Repeat("*", indirects)))
+		f.fs.Write(closeAngleBytes)
+	}
+
+	// Display pointer information depending on flags.
+	if f.fs.Flag('+') && (len(pointerChain) > 0) {
+		f.fs.Write(openParenBytes)
+		for i, addr := range pointerChain {
+			if i > 0 {
+				f.fs.Write(pointerChainBytes)
+			}
+			printHexPtr(f.fs, addr)
+		}
+		f.fs.Write(closeParenBytes)
+	}
+
+	// Display dereferenced value.
+	switch {
+	case nilFound:
+		f.fs.Write(nilAngleBytes)
+
+	case cycleFound:
+		f.fs.Write(circularShortBytes)
+
+	default:
+		f.ignoreNextType = true
+		f.format(ve)
+	}
+}
+
+// format is the main workhorse for providing the Formatter interface.  It
+// uses the passed reflect value to figure out what kind of object we are
+// dealing with and formats it appropriately.  It is a recursive function,
+// however circular data structures are detected and handled properly.
+func (f *formatState) format(v reflect.Value) {
+	// Handle invalid reflect values immediately.
+	kind := v.Kind()
+	if kind == reflect.Invalid {
+		f.fs.Write(invalidAngleBytes)
+		return
+	}
+
+	// Handle pointers specially.
+	if kind == reflect.Ptr {
+		f.formatPtr(v)
+		return
+	}
+
+	// Print type information unless already handled elsewhere.
+	if !f.ignoreNextType && f.fs.Flag('#') {
+		f.fs.Write(openParenBytes)
+		f.fs.Write([]byte(v.Type().String()))
+		f.fs.Write(closeParenBytes)
+	}
+	f.ignoreNextType = false
+
+	// Call Stringer/error interfaces if they exist and the handle methods
+	// flag is enabled.
+	if !f.cs.DisableMethods {
+		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
+			if handled := handleMethods(f.cs, f.fs, v); handled {
+				return
+			}
+		}
+	}
+
+	switch kind {
+	case reflect.Invalid:
+		// Do nothing.  We should never get here since invalid has already
+		// been handled above.
+
+	case reflect.Bool:
+		printBool(f.fs, v.Bool())
+
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		printInt(f.fs, v.Int(), 10)
+
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		printUint(f.fs, v.Uint(), 10)
+
+	case reflect.Float32:
+		printFloat(f.fs, v.Float(), 32)
+
+	case reflect.Float64:
+		printFloat(f.fs, v.Float(), 64)
+
+	case reflect.Complex64:
+		printComplex(f.fs, v.Complex(), 32)
+
+	case reflect.Complex128:
+		printComplex(f.fs, v.Complex(), 64)
+
+	case reflect.Slice:
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+			break
+		}
+		fallthrough
+
+	case reflect.Array:
+		f.fs.Write(openBracketBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			numEntries := v.Len()
+			for i := 0; i < numEntries; i++ {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				f.ignoreNextType = true
+				f.format(f.unpackValue(v.Index(i)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeBracketBytes)
+
+	case reflect.String:
+		f.fs.Write([]byte(v.String()))
+
+	case reflect.Interface:
+		// The only time we should get here is for nil interfaces due to
+		// unpackValue calls.
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+		}
+
+	case reflect.Ptr:
+		// Do nothing.  We should never get here since pointers have already
+		// been handled above.
+
+	case reflect.Map:
+		// nil maps should be indicated as different than empty maps
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+			break
+		}
+
+		f.fs.Write(openMapBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			keys := v.MapKeys()
+			if f.cs.SortKeys {
+				sortValues(keys, f.cs)
+			}
+			for i, key := range keys {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				f.ignoreNextType = true
+				f.format(f.unpackValue(key))
+				f.fs.Write(colonBytes)
+				f.ignoreNextType = true
+				f.format(f.unpackValue(v.MapIndex(key)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeMapBytes)
+
+	case reflect.Struct:
+		numFields := v.NumField()
+		f.fs.Write(openBraceBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			vt := v.Type()
+			for i := 0; i < numFields; i++ {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				vtf := vt.Field(i)
+				if f.fs.Flag('+') || f.fs.Flag('#') {
+					f.fs.Write([]byte(vtf.Name))
+					f.fs.Write(colonBytes)
+				}
+				f.format(f.unpackValue(v.Field(i)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeBraceBytes)
+
+	case reflect.Uintptr:
+		printHexPtr(f.fs, uintptr(v.Uint()))
+
+	case reflect.UnsafePointer, reflect.Chan, reflect.Func:
+		printHexPtr(f.fs, v.Pointer())
+
+	// There were not any other types at the time this code was written, but
+	// fall back to letting the default fmt package handle it if any get added.
+	default:
+		format := f.buildDefaultFormat()
+		if v.CanInterface() {
+			fmt.Fprintf(f.fs, format, v.Interface())
+		} else {
+			fmt.Fprintf(f.fs, format, v.String())
+		}
+	}
+}
+
+// Format satisfies the fmt.Formatter interface. See NewFormatter for usage
+// details.
+func (f *formatState) Format(fs fmt.State, verb rune) {
+	f.fs = fs
+
+	// Use standard formatting for verbs that are not v.
+	if verb != 'v' {
+		format := f.constructOrigFormat(verb)
+		fmt.Fprintf(fs, format, f.value)
+		return
+	}
+
+	if f.value == nil {
+		if fs.Flag('#') {
+			fs.Write(interfaceBytes)
+		}
+		fs.Write(nilAngleBytes)
+		return
+	}
+
+	f.format(reflect.ValueOf(f.value))
+}
+
+// newFormatter is a helper function to consolidate the logic from the various
+// public methods which take varying config states.
+func newFormatter(cs *ConfigState, v interface{}) fmt.Formatter {
+	fs := &formatState{value: v, cs: cs}
+	fs.pointers = make(map[uintptr]int)
+	return fs
+}
+
+/*
+NewFormatter returns a custom formatter that satisfies the fmt.Formatter
+interface.  As a result, it integrates cleanly with standard fmt package
+printing functions.  The formatter is useful for inline printing of smaller data
+types similar to the standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Typically this function shouldn't be called directly.  It is much easier to make
+use of the custom formatter by calling one of the convenience functions such as
+Printf, Println, or Fprintf.
+*/
+func NewFormatter(v interface{}) fmt.Formatter {
+	return newFormatter(&Config, v)
+}

vendor/github.com/davecgh/go-spew/spew/spew.go

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"fmt"
+	"io"
+)
+
+// Errorf is a wrapper for fmt.Errorf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the formatted string as a value that satisfies error.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Errorf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Errorf(format string, a ...interface{}) (err error) {
+	return fmt.Errorf(format, convertArgs(a)...)
+}
+
+// Fprint is a wrapper for fmt.Fprint that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprint(w, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprint(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprint(w, convertArgs(a)...)
+}
+
+// Fprintf is a wrapper for fmt.Fprintf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintf(w, format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error) {
+	return fmt.Fprintf(w, format, convertArgs(a)...)
+}
+
+// Fprintln is a wrapper for fmt.Fprintln that treats each argument as if it
+// passed with a default Formatter interface returned by NewFormatter.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintln(w, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprintln(w, convertArgs(a)...)
+}
+
+// Print is a wrapper for fmt.Print that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Print(spew.NewFormatter(a), spew.NewFormatter(b))
+func Print(a ...interface{}) (n int, err error) {
+	return fmt.Print(convertArgs(a)...)
+}
+
+// Printf is a wrapper for fmt.Printf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Printf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Printf(format string, a ...interface{}) (n int, err error) {
+	return fmt.Printf(format, convertArgs(a)...)
+}
+
+// Println is a wrapper for fmt.Println that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Println(spew.NewFormatter(a), spew.NewFormatter(b))
+func Println(a ...interface{}) (n int, err error) {
+	return fmt.Println(convertArgs(a)...)
+}
+
+// Sprint is a wrapper for fmt.Sprint that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprint(spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprint(a ...interface{}) string {
+	return fmt.Sprint(convertArgs(a)...)
+}
+
+// Sprintf is a wrapper for fmt.Sprintf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprintf(format string, a ...interface{}) string {
+	return fmt.Sprintf(format, convertArgs(a)...)
+}
+
+// Sprintln is a wrapper for fmt.Sprintln that treats each argument as if it
+// were passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintln(spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprintln(a ...interface{}) string {
+	return fmt.Sprintln(convertArgs(a)...)
+}
+
+// convertArgs accepts a slice of arguments and returns a slice of the same
+// length with each argument converted to a default spew Formatter interface.
+func convertArgs(args []interface{}) (formatters []interface{}) {
+	formatters = make([]interface{}, len(args))
+	for index, arg := range args {
+		formatters[index] = NewFormatter(arg)
+	}
+	return formatters
+}

vendor/github.com/dgrijalva/jwt-go/.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+bin
+
+

vendor/github.com/dgrijalva/jwt-go/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+script:
+    - go vet ./...
+    - go test -v ./...
+
+go:
+  - 1.3
+  - 1.4
+  - 1.5
+  - 1.6
+  - 1.7
+  - tip

vendor/github.com/dgrijalva/jwt-go/LICENSE

@@ -0,0 +1,8 @@
+Copyright (c) 2012 Dave Grijalva
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

vendor/github.com/dgrijalva/jwt-go/MIGRATION_GUIDE.md

@@ -0,0 +1,97 @@
+## Migration Guide from v2 -> v3
+
+Version 3 adds several new, frequently requested features.  To do so, it introduces a few breaking changes.  We've worked to keep these as minimal as possible.  This guide explains the breaking changes and how you can quickly update your code.
+
+### `Token.Claims` is now an interface type
+
+The most requested feature from the 2.0 verison of this library was the ability to provide a custom type to the JSON parser for claims. This was implemented by introducing a new interface, `Claims`, to replace `map[string]interface{}`.  We also included two concrete implementations of `Claims`: `MapClaims` and `StandardClaims`.
+
+`MapClaims` is an alias for `map[string]interface{}` with built in validation behavior.  It is the default claims type when using `Parse`.  The usage is unchanged except you must type cast the claims property.
+
+The old example for parsing a token looked like this..
+
+```go
+	if token, err := jwt.Parse(tokenString, keyLookupFunc); err == nil {
+		fmt.Printf("Token for user %v expires %v", token.Claims["user"], token.Claims["exp"])
+	}
+```
+
+is now directly mapped to...
+
+```go
+	if token, err := jwt.Parse(tokenString, keyLookupFunc); err == nil {
+		claims := token.Claims.(jwt.MapClaims)
+		fmt.Printf("Token for user %v expires %v", claims["user"], claims["exp"])
+	}
+```
+
+`StandardClaims` is designed to be embedded in your custom type.  You can supply a custom claims type with the new `ParseWithClaims` function.  Here's an example of using a custom claims type.
+
+```go
+	type MyCustomClaims struct {
+		User string
+		*StandardClaims
+	}
+	
+	if token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, keyLookupFunc); err == nil {
+		claims := token.Claims.(*MyCustomClaims)
+		fmt.Printf("Token for user %v expires %v", claims.User, claims.StandardClaims.ExpiresAt)
+	}
+```
+
+### `ParseFromRequest` has been moved
+
+To keep this library focused on the tokens without becoming overburdened with complex request processing logic, `ParseFromRequest` and its new companion `ParseFromRequestWithClaims` have been moved to a subpackage, `request`.  The method signatues have also been augmented to receive a new argument: `Extractor`.
+
+`Extractors` do the work of picking the token string out of a request.  The interface is simple and composable.
+
+This simple parsing example:
+
+```go
+	if token, err := jwt.ParseFromRequest(tokenString, req, keyLookupFunc); err == nil {
+		fmt.Printf("Token for user %v expires %v", token.Claims["user"], token.Claims["exp"])
+	}
+```
+
+is directly mapped to:
+
+```go
+	if token, err := request.ParseFromRequest(req, request.OAuth2Extractor, keyLookupFunc); err == nil {
+		claims := token.Claims.(jwt.MapClaims)
+		fmt.Printf("Token for user %v expires %v", claims["user"], claims["exp"])
+	}
+```
+
+There are several concrete `Extractor` types provided for your convenience:
+
+* `HeaderExtractor` will search a list of headers until one contains content.
+* `ArgumentExtractor` will search a list of keys in request query and form arguments until one contains content.
+* `MultiExtractor` will try a list of `Extractors` in order until one returns content.
+* `AuthorizationHeaderExtractor` will look in the `Authorization` header for a `Bearer` token.
+* `OAuth2Extractor` searches the places an OAuth2 token would be specified (per the spec): `Authorization` header and `access_token` argument
+* `PostExtractionFilter` wraps an `Extractor`, allowing you to process the content before it's parsed.  A simple example is stripping the `Bearer ` text from a header
+
+
+### RSA signing methods no longer accept `[]byte` keys
+
+Due to a [critical vulnerability](https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/), we've decided the convenience of accepting `[]byte` instead of `rsa.PublicKey` or `rsa.PrivateKey` isn't worth the risk of misuse.
+
+To replace this behavior, we've added two helper methods: `ParseRSAPrivateKeyFromPEM(key []byte) (*rsa.PrivateKey, error)` and `ParseRSAPublicKeyFromPEM(key []byte) (*rsa.PublicKey, error)`.  These are just simple helpers for unpacking PEM encoded PKCS1 and PKCS8 keys. If your keys are encoded any other way, all you need to do is convert them to the `crypto/rsa` package's types.
+
+```go 
+	func keyLookupFunc(*Token) (interface{}, error) {
+		// Don't forget to validate the alg is what you expect:
+		if _, ok := token.Method.(*jwt.SigningMethodRSA); !ok {
+			return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
+		}
+		
+		// Look up key 
+		key, err := lookupPublicKey(token.Header["kid"])
+		if err != nil {
+			return nil, err
+		}
+		
+		// Unpack key from PEM encoded PKCS8
+		return jwt.ParseRSAPublicKeyFromPEM(key)
+	}
+```

vendor/github.com/dgrijalva/jwt-go/README.md

@@ -0,0 +1,100 @@
+# jwt-go
+
+[![Build Status](https://travis-ci.org/dgrijalva/jwt-go.svg?branch=master)](https://travis-ci.org/dgrijalva/jwt-go)
+[![GoDoc](https://godoc.org/github.com/dgrijalva/jwt-go?status.svg)](https://godoc.org/github.com/dgrijalva/jwt-go)
+
+A [go](http://www.golang.org) (or 'golang' for search engine friendliness) implementation of [JSON Web Tokens](http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html)
+
+**NEW VERSION COMING:** There have been a lot of improvements suggested since the version 3.0.0 released in 2016. I'm working now on cutting two different releases: 3.2.0 will contain any non-breaking changes or enhancements. 4.0.0 will follow shortly which will include breaking changes. See the 4.0.0 milestone to get an idea of what's coming. If you have other ideas, or would like to participate in 4.0.0, now's the time. If you depend on this library and don't want to be interrupted, I recommend you use your dependency mangement tool to pin to version 3. 
+
+**SECURITY NOTICE:** Some older versions of Go have a security issue in the cryotp/elliptic. Recommendation is to upgrade to at least 1.8.3. See issue #216 for more detail.
+
+**SECURITY NOTICE:** It's important that you [validate the `alg` presented is what you expect](https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/). This library attempts to make it easy to do the right thing by requiring key types match the expected alg, but you should take the extra step to verify it in your usage.  See the examples provided.
+
+## What the heck is a JWT?
+
+JWT.io has [a great introduction](https://jwt.io/introduction) to JSON Web Tokens.
+
+In short, it's a signed JSON object that does something useful (for example, authentication).  It's commonly used for `Bearer` tokens in Oauth 2.  A token is made of three parts, separated by `.`'s.  The first two parts are JSON objects, that have been [base64url](http://tools.ietf.org/html/rfc4648) encoded.  The last part is the signature, encoded the same way.
+
+The first part is called the header.  It contains the necessary information for verifying the last part, the signature.  For example, which encryption method was used for signing and what key was used.
+
+The part in the middle is the interesting bit.  It's called the Claims and contains the actual stuff you care about.  Refer to [the RFC](http://self-issued.info/docs/draft-jones-json-web-token.html) for information about reserved keys and the proper way to add your own.
+
+## What's in the box?
+
+This library supports the parsing and verification as well as the generation and signing of JWTs.  Current supported signing algorithms are HMAC SHA, RSA, RSA-PSS, and ECDSA, though hooks are present for adding your own.
+
+## Examples
+
+See [the project documentation](https://godoc.org/github.com/dgrijalva/jwt-go) for examples of usage:
+
+* [Simple example of parsing and validating a token](https://godoc.org/github.com/dgrijalva/jwt-go#example-Parse--Hmac)
+* [Simple example of building and signing a token](https://godoc.org/github.com/dgrijalva/jwt-go#example-New--Hmac)
+* [Directory of Examples](https://godoc.org/github.com/dgrijalva/jwt-go#pkg-examples)
+
+## Extensions
+
+This library publishes all the necessary components for adding your own signing methods.  Simply implement the `SigningMethod` interface and register a factory method using `RegisterSigningMethod`.  
+
+Here's an example of an extension that integrates with the Google App Engine signing tools: https://github.com/someone1/gcp-jwt-go
+
+## Compliance
+
+This library was last reviewed to comply with [RTF 7519](http://www.rfc-editor.org/info/rfc7519) dated May 2015 with a few notable differences:
+
+* In order to protect against accidental use of [Unsecured JWTs](http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html#UnsecuredJWT), tokens using `alg=none` will only be accepted if the constant `jwt.UnsafeAllowNoneSignatureType` is provided as the key.
+
+## Project Status & Versioning
+
+This library is considered production ready.  Feedback and feature requests are appreciated.  The API should be considered stable.  There should be very few backwards-incompatible changes outside of major version updates (and only with good reason).
+
+This project uses [Semantic Versioning 2.0.0](http://semver.org).  Accepted pull requests will land on `master`.  Periodically, versions will be tagged from `master`.  You can find all the releases on [the project releases page](https://github.com/dgrijalva/jwt-go/releases).
+
+While we try to make it obvious when we make breaking changes, there isn't a great mechanism for pushing announcements out to users.  You may want to use this alternative package include: `gopkg.in/dgrijalva/jwt-go.v3`.  It will do the right thing WRT semantic versioning.
+
+**BREAKING CHANGES:*** 
+* Version 3.0.0 includes _a lot_ of changes from the 2.x line, including a few that break the API.  We've tried to break as few things as possible, so there should just be a few type signature changes.  A full list of breaking changes is available in `VERSION_HISTORY.md`.  See `MIGRATION_GUIDE.md` for more information on updating your code.
+
+## Usage Tips
+
+### Signing vs Encryption
+
+A token is simply a JSON object that is signed by its author. this tells you exactly two things about the data:
+
+* The author of the token was in the possession of the signing secret
+* The data has not been modified since it was signed
+
+It's important to know that JWT does not provide encryption, which means anyone who has access to the token can read its contents. If you need to protect (encrypt) the data, there is a companion spec, `JWE`, that provides this functionality. JWE is currently outside the scope of this library.
+
+### Choosing a Signing Method
+
+There are several signing methods available, and you should probably take the time to learn about the various options before choosing one.  The principal design decision is most likely going to be symmetric vs asymmetric.
+
+Symmetric signing methods, such as HSA, use only a single secret. This is probably the simplest signing method to use since any `[]byte` can be used as a valid secret. They are also slightly computationally faster to use, though this rarely is enough to matter. Symmetric signing methods work the best when both producers and consumers of tokens are trusted, or even the same system. Since the same secret is used to both sign and validate tokens, you can't easily distribute the key for validation.
+
+Asymmetric signing methods, such as RSA, use different keys for signing and verifying tokens. This makes it possible to produce tokens with a private key, and allow any consumer to access the public key for verification.
+
+### Signing Methods and Key Types
+
+Each signing method expects a different object type for its signing keys. See the package documentation for details. Here are the most common ones:
+
+* The [HMAC signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodHMAC) (`HS256`,`HS384`,`HS512`) expect `[]byte` values for signing and validation
+* The [RSA signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodRSA) (`RS256`,`RS384`,`RS512`) expect `*rsa.PrivateKey` for signing and `*rsa.PublicKey` for validation
+* The [ECDSA signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodECDSA) (`ES256`,`ES384`,`ES512`) expect `*ecdsa.PrivateKey` for signing and `*ecdsa.PublicKey` for validation
+
+### JWT and OAuth
+
+It's worth mentioning that OAuth and JWT are not the same thing. A JWT token is simply a signed JSON object. It can be used anywhere such a thing is useful. There is some confusion, though, as JWT is the most common type of bearer token used in OAuth2 authentication.
+
+Without going too far down the rabbit hole, here's a description of the interaction of these technologies:
+
+* OAuth is a protocol for allowing an identity provider to be separate from the service a user is logging in to. For example, whenever you use Facebook to log into a different service (Yelp, Spotify, etc), you are using OAuth.
+* OAuth defines several options for passing around authentication data. One popular method is called a "bearer token". A bearer token is simply a string that _should_ only be held by an authenticated user. Thus, simply presenting this token proves your identity. You can probably derive from here why a JWT might make a good bearer token.
+* Because bearer tokens are used for authentication, it's important they're kept secret. This is why transactions that use bearer tokens typically happen over SSL.
+
+## More
+
+Documentation can be found [on godoc.org](http://godoc.org/github.com/dgrijalva/jwt-go).
+
+The command line utility included in this project (cmd/jwt) provides a straightforward example of token creation and parsing as well as a useful tool for debugging your own integration. You'll also find several implementation examples in the documentation.

vendor/github.com/dgrijalva/jwt-go/VERSION_HISTORY.md

@@ -0,0 +1,118 @@
+## `jwt-go` Version History
+
+#### 3.2.0
+
+* Added method `ParseUnverified` to allow users to split up the tasks of parsing and validation
+* HMAC signing method returns `ErrInvalidKeyType` instead of `ErrInvalidKey` where appropriate
+* Added options to `request.ParseFromRequest`, which allows for an arbitrary list of modifiers to parsing behavior. Initial set include `WithClaims` and `WithParser`. Existing usage of this function will continue to work as before.
+* Deprecated `ParseFromRequestWithClaims` to simplify API in the future.
+
+#### 3.1.0
+
+* Improvements to `jwt` command line tool
+* Added `SkipClaimsValidation` option to `Parser`
+* Documentation updates
+
+#### 3.0.0
+
+* **Compatibility Breaking Changes**: See MIGRATION_GUIDE.md for tips on updating your code
+	* Dropped support for `[]byte` keys when using RSA signing methods.  This convenience feature could contribute to security vulnerabilities involving mismatched key types with signing methods.
+	* `ParseFromRequest` has been moved to `request` subpackage and usage has changed
+	* The `Claims` property on `Token` is now type `Claims` instead of `map[string]interface{}`.  The default value is type `MapClaims`, which is an alias to `map[string]interface{}`.  This makes it possible to use a custom type when decoding claims.
+* Other Additions and Changes
+	* Added `Claims` interface type to allow users to decode the claims into a custom type
+	* Added `ParseWithClaims`, which takes a third argument of type `Claims`.  Use this function instead of `Parse` if you have a custom type you'd like to decode into.
+	* Dramatically improved the functionality and flexibility of `ParseFromRequest`, which is now in the `request` subpackage
+	* Added `ParseFromRequestWithClaims` which is the `FromRequest` equivalent of `ParseWithClaims`
+	* Added new interface type `Extractor`, which is used for extracting JWT strings from http requests.  Used with `ParseFromRequest` and `ParseFromRequestWithClaims`.
+	* Added several new, more specific, validation errors to error type bitmask
+	* Moved examples from README to executable example files
+	* Signing method registry is now thread safe
+	* Added new property to `ValidationError`, which contains the raw error returned by calls made by parse/verify (such as those returned by keyfunc or json parser)
+
+#### 2.7.0
+
+This will likely be the last backwards compatible release before 3.0.0, excluding essential bug fixes.
+
+* Added new option `-show` to the `jwt` command that will just output the decoded token without verifying
+* Error text for expired tokens includes how long it's been expired
+* Fixed incorrect error returned from `ParseRSAPublicKeyFromPEM`
+* Documentation updates
+
+#### 2.6.0
+
+* Exposed inner error within ValidationError
+* Fixed validation errors when using UseJSONNumber flag
+* Added several unit tests
+
+#### 2.5.0
+
+* Added support for signing method none.  You shouldn't use this.  The API tries to make this clear.
+* Updated/fixed some documentation
+* Added more helpful error message when trying to parse tokens that begin with `BEARER `
+
+#### 2.4.0
+
+* Added new type, Parser, to allow for configuration of various parsing parameters
+	* You can now specify a list of valid signing methods.  Anything outside this set will be rejected.
+	* You can now opt to use the `json.Number` type instead of `float64` when parsing token JSON
+* Added support for [Travis CI](https://travis-ci.org/dgrijalva/jwt-go)
+* Fixed some bugs with ECDSA parsing
+
+#### 2.3.0
+
+* Added support for ECDSA signing methods
+* Added support for RSA PSS signing methods (requires go v1.4)
+
+#### 2.2.0
+
+* Gracefully handle a `nil` `Keyfunc` being passed to `Parse`.  Result will now be the parsed token and an error, instead of a panic.
+
+#### 2.1.0
+
+Backwards compatible API change that was missed in 2.0.0.
+
+* The `SignedString` method on `Token` now takes `interface{}` instead of `[]byte`
+
+#### 2.0.0
+
+There were two major reasons for breaking backwards compatibility with this update.  The first was a refactor required to expand the width of the RSA and HMAC-SHA signing implementations.  There will likely be no required code changes to support this change.
+
+The second update, while unfortunately requiring a small change in integration, is required to open up this library to other signing methods.  Not all keys used for all signing methods have a single standard on-disk representation.  Requiring `[]byte` as the type for all keys proved too limiting.  Additionally, this implementation allows for pre-parsed tokens to be reused, which might matter in an application that parses a high volume of tokens with a small set of keys.  Backwards compatibilty has been maintained for passing `[]byte` to the RSA signing methods, but they will also accept `*rsa.PublicKey` and `*rsa.PrivateKey`.
+
+It is likely the only integration change required here will be to change `func(t *jwt.Token) ([]byte, error)` to `func(t *jwt.Token) (interface{}, error)` when calling `Parse`.
+
+* **Compatibility Breaking Changes**
+	* `SigningMethodHS256` is now `*SigningMethodHMAC` instead of `type struct`
+	* `SigningMethodRS256` is now `*SigningMethodRSA` instead of `type struct`
+	* `KeyFunc` now returns `interface{}` instead of `[]byte`
+	* `SigningMethod.Sign` now takes `interface{}` instead of `[]byte` for the key
+	* `SigningMethod.Verify` now takes `interface{}` instead of `[]byte` for the key
+* Renamed type `SigningMethodHS256` to `SigningMethodHMAC`.  Specific sizes are now just instances of this type.
+    * Added public package global `SigningMethodHS256`
+    * Added public package global `SigningMethodHS384`
+    * Added public package global `SigningMethodHS512`
+* Renamed type `SigningMethodRS256` to `SigningMethodRSA`.  Specific sizes are now just instances of this type.
+    * Added public package global `SigningMethodRS256`
+    * Added public package global `SigningMethodRS384`
+    * Added public package global `SigningMethodRS512`
+* Moved sample private key for HMAC tests from an inline value to a file on disk.  Value is unchanged.
+* Refactored the RSA implementation to be easier to read
+* Exposed helper methods `ParseRSAPrivateKeyFromPEM` and `ParseRSAPublicKeyFromPEM`
+
+#### 1.0.2
+
+* Fixed bug in parsing public keys from certificates
+* Added more tests around the parsing of keys for RS256
+* Code refactoring in RS256 implementation.  No functional changes
+
+#### 1.0.1
+
+* Fixed panic if RS256 signing method was passed an invalid key
+
+#### 1.0.0
+
+* First versioned release
+* API stabilized
+* Supports creating, signing, parsing, and validating JWT tokens
+* Supports RS256 and HS256 signing methods

vendor/github.com/dgrijalva/jwt-go/claims.go

@@ -0,0 +1,134 @@
+package jwt
+
+import (
+	"crypto/subtle"
+	"fmt"
+	"time"
+)
+
+// For a type to be a Claims object, it must just have a Valid method that determines
+// if the token is invalid for any supported reason
+type Claims interface {
+	Valid() error
+}
+
+// Structured version of Claims Section, as referenced at
+// https://tools.ietf.org/html/rfc7519#section-4.1
+// See examples for how to use this with your own claim types
+type StandardClaims struct {
+	Audience  string `json:"aud,omitempty"`
+	ExpiresAt int64  `json:"exp,omitempty"`
+	Id        string `json:"jti,omitempty"`
+	IssuedAt  int64  `json:"iat,omitempty"`
+	Issuer    string `json:"iss,omitempty"`
+	NotBefore int64  `json:"nbf,omitempty"`
+	Subject   string `json:"sub,omitempty"`
+}
+
+// Validates time based claims "exp, iat, nbf".
+// There is no accounting for clock skew.
+// As well, if any of the above claims are not in the token, it will still
+// be considered a valid claim.
+func (c StandardClaims) Valid() error {
+	vErr := new(ValidationError)
+	now := TimeFunc().Unix()
+
+	// The claims below are optional, by default, so if they are set to the
+	// default value in Go, let's not fail the verification for them.
+	if c.VerifyExpiresAt(now, false) == false {
+		delta := time.Unix(now, 0).Sub(time.Unix(c.ExpiresAt, 0))
+		vErr.Inner = fmt.Errorf("token is expired by %v", delta)
+		vErr.Errors |= ValidationErrorExpired
+	}
+
+	if c.VerifyIssuedAt(now, false) == false {
+		vErr.Inner = fmt.Errorf("Token used before issued")
+		vErr.Errors |= ValidationErrorIssuedAt
+	}
+
+	if c.VerifyNotBefore(now, false) == false {
+		vErr.Inner = fmt.Errorf("token is not valid yet")
+		vErr.Errors |= ValidationErrorNotValidYet
+	}
+
+	if vErr.valid() {
+		return nil
+	}
+
+	return vErr
+}
+
+// Compares the aud claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyAudience(cmp string, req bool) bool {
+	return verifyAud(c.Audience, cmp, req)
+}
+
+// Compares the exp claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyExpiresAt(cmp int64, req bool) bool {
+	return verifyExp(c.ExpiresAt, cmp, req)
+}
+
+// Compares the iat claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuedAt(cmp int64, req bool) bool {
+	return verifyIat(c.IssuedAt, cmp, req)
+}
+
+// Compares the iss claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuer(cmp string, req bool) bool {
+	return verifyIss(c.Issuer, cmp, req)
+}
+
+// Compares the nbf claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyNotBefore(cmp int64, req bool) bool {
+	return verifyNbf(c.NotBefore, cmp, req)
+}
+
+// ----- helpers
+
+func verifyAud(aud string, cmp string, required bool) bool {
+	if aud == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(aud), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyExp(exp int64, now int64, required bool) bool {
+	if exp == 0 {
+		return !required
+	}
+	return now <= exp
+}
+
+func verifyIat(iat int64, now int64, required bool) bool {
+	if iat == 0 {
+		return !required
+	}
+	return now >= iat
+}
+
+func verifyIss(iss string, cmp string, required bool) bool {
+	if iss == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(iss), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyNbf(nbf int64, now int64, required bool) bool {
+	if nbf == 0 {
+		return !required
+	}
+	return now >= nbf
+}

vendor/github.com/dgrijalva/jwt-go/doc.go

@@ -0,0 +1,4 @@
+// Package jwt is a Go implementation of JSON Web Tokens: http://self-issued.info/docs/draft-jones-json-web-token.html
+//
+// See README.md for more info.
+package jwt

vendor/github.com/dgrijalva/jwt-go/ecdsa.go

@@ -0,0 +1,148 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/rand"
+	"errors"
+	"math/big"
+)
+
+var (
+	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
+	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
+)
+
+// Implements the ECDSA family of signing methods signing methods
+// Expects *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for verification
+type SigningMethodECDSA struct {
+	Name      string
+	Hash      crypto.Hash
+	KeySize   int
+	CurveBits int
+}
+
+// Specific instances for EC256 and company
+var (
+	SigningMethodES256 *SigningMethodECDSA
+	SigningMethodES384 *SigningMethodECDSA
+	SigningMethodES512 *SigningMethodECDSA
+)
+
+func init() {
+	// ES256
+	SigningMethodES256 = &SigningMethodECDSA{"ES256", crypto.SHA256, 32, 256}
+	RegisterSigningMethod(SigningMethodES256.Alg(), func() SigningMethod {
+		return SigningMethodES256
+	})
+
+	// ES384
+	SigningMethodES384 = &SigningMethodECDSA{"ES384", crypto.SHA384, 48, 384}
+	RegisterSigningMethod(SigningMethodES384.Alg(), func() SigningMethod {
+		return SigningMethodES384
+	})
+
+	// ES512
+	SigningMethodES512 = &SigningMethodECDSA{"ES512", crypto.SHA512, 66, 521}
+	RegisterSigningMethod(SigningMethodES512.Alg(), func() SigningMethod {
+		return SigningMethodES512
+	})
+}
+
+func (m *SigningMethodECDSA) Alg() string {
+	return m.Name
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an ecdsa.PublicKey struct
+func (m *SigningMethodECDSA) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	// Get the key
+	var ecdsaKey *ecdsa.PublicKey
+	switch k := key.(type) {
+	case *ecdsa.PublicKey:
+		ecdsaKey = k
+	default:
+		return ErrInvalidKeyType
+	}
+
+	if len(sig) != 2*m.KeySize {
+		return ErrECDSAVerification
+	}
+
+	r := big.NewInt(0).SetBytes(sig[:m.KeySize])
+	s := big.NewInt(0).SetBytes(sig[m.KeySize:])
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	if verifystatus := ecdsa.Verify(ecdsaKey, hasher.Sum(nil), r, s); verifystatus == true {
+		return nil
+	} else {
+		return ErrECDSAVerification
+	}
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an ecdsa.PrivateKey struct
+func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string, error) {
+	// Get the key
+	var ecdsaKey *ecdsa.PrivateKey
+	switch k := key.(type) {
+	case *ecdsa.PrivateKey:
+		ecdsaKey = k
+	default:
+		return "", ErrInvalidKeyType
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return r, s
+	if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
+		curveBits := ecdsaKey.Curve.Params().BitSize
+
+		if m.CurveBits != curveBits {
+			return "", ErrInvalidKey
+		}
+
+		keyBytes := curveBits / 8
+		if curveBits%8 > 0 {
+			keyBytes += 1
+		}
+
+		// We serialize the outpus (r and s) into big-endian byte arrays and pad
+		// them with zeros on the left to make sure the sizes work out. Both arrays
+		// must be keyBytes long, and the output must be 2*keyBytes long.
+		rBytes := r.Bytes()
+		rBytesPadded := make([]byte, keyBytes)
+		copy(rBytesPadded[keyBytes-len(rBytes):], rBytes)
+
+		sBytes := s.Bytes()
+		sBytesPadded := make([]byte, keyBytes)
+		copy(sBytesPadded[keyBytes-len(sBytes):], sBytes)
+
+		out := append(rBytesPadded, sBytesPadded...)
+
+		return EncodeSegment(out), nil
+	} else {
+		return "", err
+	}
+}

vendor/github.com/dgrijalva/jwt-go/ecdsa_utils.go

@@ -0,0 +1,67 @@
+package jwt
+
+import (
+	"crypto/ecdsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+)
+
+var (
+	ErrNotECPublicKey  = errors.New("Key is not a valid ECDSA public key")
+	ErrNotECPrivateKey = errors.New("Key is not a valid ECDSA private key")
+)
+
+// Parse PEM encoded Elliptic Curve Private Key Structure
+func ParseECPrivateKeyFromPEM(key []byte) (*ecdsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParseECPrivateKey(block.Bytes); err != nil {
+		return nil, err
+	}
+
+	var pkey *ecdsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PrivateKey); !ok {
+		return nil, ErrNotECPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 public key
+func ParseECPublicKeyFromPEM(key []byte) (*ecdsa.PublicKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
+		if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
+			parsedKey = cert.PublicKey
+		} else {
+			return nil, err
+		}
+	}
+
+	var pkey *ecdsa.PublicKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PublicKey); !ok {
+		return nil, ErrNotECPublicKey
+	}
+
+	return pkey, nil
+}

vendor/github.com/dgrijalva/jwt-go/errors.go

@@ -0,0 +1,59 @@
+package jwt
+
+import (
+	"errors"
+)
+
+// Error constants
+var (
+	ErrInvalidKey      = errors.New("key is invalid")
+	ErrInvalidKeyType  = errors.New("key is of invalid type")
+	ErrHashUnavailable = errors.New("the requested hash function is unavailable")
+)
+
+// The errors that might occur when parsing and validating a token
+const (
+	ValidationErrorMalformed        uint32 = 1 << iota // Token is malformed
+	ValidationErrorUnverifiable                        // Token could not be verified because of signing problems
+	ValidationErrorSignatureInvalid                    // Signature validation failed
+
+	// Standard Claim validation errors
+	ValidationErrorAudience      // AUD validation failed
+	ValidationErrorExpired       // EXP validation failed
+	ValidationErrorIssuedAt      // IAT validation failed
+	ValidationErrorIssuer        // ISS validation failed
+	ValidationErrorNotValidYet   // NBF validation failed
+	ValidationErrorId            // JTI validation failed
+	ValidationErrorClaimsInvalid // Generic claims validation error
+)
+
+// Helper for constructing a ValidationError with a string error message
+func NewValidationError(errorText string, errorFlags uint32) *ValidationError {
+	return &ValidationError{
+		text:   errorText,
+		Errors: errorFlags,
+	}
+}
+
+// The error from Parse if token is not valid
+type ValidationError struct {
+	Inner  error  // stores the error returned by external dependencies, i.e.: KeyFunc
+	Errors uint32 // bitfield.  see ValidationError... constants
+	text   string // errors that do not have a valid error just have text
+}
+
+// Validation error is an error type
+func (e ValidationError) Error() string {
+	if e.Inner != nil {
+		return e.Inner.Error()
+	} else if e.text != "" {
+		return e.text
+	} else {
+		return "token is invalid"
+	}
+}
+
+// No errors
+func (e *ValidationError) valid() bool {
+	return e.Errors == 0
+}

vendor/github.com/dgrijalva/jwt-go/hmac.go

@@ -0,0 +1,95 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/hmac"
+	"errors"
+)
+
+// Implements the HMAC-SHA family of signing methods signing methods
+// Expects key type of []byte for both signing and validation
+type SigningMethodHMAC struct {
+	Name string
+	Hash crypto.Hash
+}
+
+// Specific instances for HS256 and company
+var (
+	SigningMethodHS256  *SigningMethodHMAC
+	SigningMethodHS384  *SigningMethodHMAC
+	SigningMethodHS512  *SigningMethodHMAC
+	ErrSignatureInvalid = errors.New("signature is invalid")
+)
+
+func init() {
+	// HS256
+	SigningMethodHS256 = &SigningMethodHMAC{"HS256", crypto.SHA256}
+	RegisterSigningMethod(SigningMethodHS256.Alg(), func() SigningMethod {
+		return SigningMethodHS256
+	})
+
+	// HS384
+	SigningMethodHS384 = &SigningMethodHMAC{"HS384", crypto.SHA384}
+	RegisterSigningMethod(SigningMethodHS384.Alg(), func() SigningMethod {
+		return SigningMethodHS384
+	})
+
+	// HS512
+	SigningMethodHS512 = &SigningMethodHMAC{"HS512", crypto.SHA512}
+	RegisterSigningMethod(SigningMethodHS512.Alg(), func() SigningMethod {
+		return SigningMethodHS512
+	})
+}
+
+func (m *SigningMethodHMAC) Alg() string {
+	return m.Name
+}
+
+// Verify the signature of HSXXX tokens.  Returns nil if the signature is valid.
+func (m *SigningMethodHMAC) Verify(signingString, signature string, key interface{}) error {
+	// Verify the key is the right type
+	keyBytes, ok := key.([]byte)
+	if !ok {
+		return ErrInvalidKeyType
+	}
+
+	// Decode signature, for comparison
+	sig, err := DecodeSegment(signature)
+	if err != nil {
+		return err
+	}
+
+	// Can we use the specified hashing method?
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+
+	// This signing method is symmetric, so we validate the signature
+	// by reproducing the signature from the signing string and key, then
+	// comparing that against the provided signature.
+	hasher := hmac.New(m.Hash.New, keyBytes)
+	hasher.Write([]byte(signingString))
+	if !hmac.Equal(sig, hasher.Sum(nil)) {
+		return ErrSignatureInvalid
+	}
+
+	// No validation errors.  Signature is good.
+	return nil
+}
+
+// Implements the Sign method from SigningMethod for this signing method.
+// Key must be []byte
+func (m *SigningMethodHMAC) Sign(signingString string, key interface{}) (string, error) {
+	if keyBytes, ok := key.([]byte); ok {
+		if !m.Hash.Available() {
+			return "", ErrHashUnavailable
+		}
+
+		hasher := hmac.New(m.Hash.New, keyBytes)
+		hasher.Write([]byte(signingString))
+
+		return EncodeSegment(hasher.Sum(nil)), nil
+	}
+
+	return "", ErrInvalidKeyType
+}

vendor/github.com/dgrijalva/jwt-go/map_claims.go

@@ -0,0 +1,94 @@
+package jwt
+
+import (
+	"encoding/json"
+	"errors"
+	// "fmt"
+)
+
+// Claims type that uses the map[string]interface{} for JSON decoding
+// This is the default claims type if you don't supply one
+type MapClaims map[string]interface{}
+
+// Compares the aud claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyAudience(cmp string, req bool) bool {
+	aud, _ := m["aud"].(string)
+	return verifyAud(aud, cmp, req)
+}
+
+// Compares the exp claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyExpiresAt(cmp int64, req bool) bool {
+	switch exp := m["exp"].(type) {
+	case float64:
+		return verifyExp(int64(exp), cmp, req)
+	case json.Number:
+		v, _ := exp.Int64()
+		return verifyExp(v, cmp, req)
+	}
+	return req == false
+}
+
+// Compares the iat claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyIssuedAt(cmp int64, req bool) bool {
+	switch iat := m["iat"].(type) {
+	case float64:
+		return verifyIat(int64(iat), cmp, req)
+	case json.Number:
+		v, _ := iat.Int64()
+		return verifyIat(v, cmp, req)
+	}
+	return req == false
+}
+
+// Compares the iss claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyIssuer(cmp string, req bool) bool {
+	iss, _ := m["iss"].(string)
+	return verifyIss(iss, cmp, req)
+}
+
+// Compares the nbf claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyNotBefore(cmp int64, req bool) bool {
+	switch nbf := m["nbf"].(type) {
+	case float64:
+		return verifyNbf(int64(nbf), cmp, req)
+	case json.Number:
+		v, _ := nbf.Int64()
+		return verifyNbf(v, cmp, req)
+	}
+	return req == false
+}
+
+// Validates time based claims "exp, iat, nbf".
+// There is no accounting for clock skew.
+// As well, if any of the above claims are not in the token, it will still
+// be considered a valid claim.
+func (m MapClaims) Valid() error {
+	vErr := new(ValidationError)
+	now := TimeFunc().Unix()
+
+	if m.VerifyExpiresAt(now, false) == false {
+		vErr.Inner = errors.New("Token is expired")
+		vErr.Errors |= ValidationErrorExpired
+	}
+
+	if m.VerifyIssuedAt(now, false) == false {
+		vErr.Inner = errors.New("Token used before issued")
+		vErr.Errors |= ValidationErrorIssuedAt
+	}
+
+	if m.VerifyNotBefore(now, false) == false {
+		vErr.Inner = errors.New("Token is not valid yet")
+		vErr.Errors |= ValidationErrorNotValidYet
+	}
+
+	if vErr.valid() {
+		return nil
+	}
+
+	return vErr
+}

vendor/github.com/dgrijalva/jwt-go/none.go

@@ -0,0 +1,52 @@
+package jwt
+
+// Implements the none signing method.  This is required by the spec
+// but you probably should never use it.
+var SigningMethodNone *signingMethodNone
+
+const UnsafeAllowNoneSignatureType unsafeNoneMagicConstant = "none signing method allowed"
+
+var NoneSignatureTypeDisallowedError error
+
+type signingMethodNone struct{}
+type unsafeNoneMagicConstant string
+
+func init() {
+	SigningMethodNone = &signingMethodNone{}
+	NoneSignatureTypeDisallowedError = NewValidationError("'none' signature type is not allowed", ValidationErrorSignatureInvalid)
+
+	RegisterSigningMethod(SigningMethodNone.Alg(), func() SigningMethod {
+		return SigningMethodNone
+	})
+}
+
+func (m *signingMethodNone) Alg() string {
+	return "none"
+}
+
+// Only allow 'none' alg type if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Verify(signingString, signature string, key interface{}) (err error) {
+	// Key must be UnsafeAllowNoneSignatureType to prevent accidentally
+	// accepting 'none' signing method
+	if _, ok := key.(unsafeNoneMagicConstant); !ok {
+		return NoneSignatureTypeDisallowedError
+	}
+	// If signing method is none, signature must be an empty string
+	if signature != "" {
+		return NewValidationError(
+			"'none' signing method with non-empty signature",
+			ValidationErrorSignatureInvalid,
+		)
+	}
+
+	// Accept 'none' signing method.
+	return nil
+}
+
+// Only allow 'none' signing if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Sign(signingString string, key interface{}) (string, error) {
+	if _, ok := key.(unsafeNoneMagicConstant); ok {
+		return "", nil
+	}
+	return "", NoneSignatureTypeDisallowedError
+}

vendor/github.com/dgrijalva/jwt-go/parser.go

@@ -0,0 +1,148 @@
+package jwt
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+type Parser struct {
+	ValidMethods         []string // If populated, only these methods will be considered valid
+	UseJSONNumber        bool     // Use JSON Number format in JSON decoder
+	SkipClaimsValidation bool     // Skip claims validation during token parsing
+}
+
+// Parse, validate, and return a token.
+// keyFunc will receive the parsed token and should return the key for validating.
+// If everything is kosher, err will be nil
+func (p *Parser) Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
+	return p.ParseWithClaims(tokenString, MapClaims{}, keyFunc)
+}
+
+func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
+	token, parts, err := p.ParseUnverified(tokenString, claims)
+	if err != nil {
+		return token, err
+	}
+
+	// Verify signing method is in the required set
+	if p.ValidMethods != nil {
+		var signingMethodValid = false
+		var alg = token.Method.Alg()
+		for _, m := range p.ValidMethods {
+			if m == alg {
+				signingMethodValid = true
+				break
+			}
+		}
+		if !signingMethodValid {
+			// signing method is not in the listed set
+			return token, NewValidationError(fmt.Sprintf("signing method %v is invalid", alg), ValidationErrorSignatureInvalid)
+		}
+	}
+
+	// Lookup key
+	var key interface{}
+	if keyFunc == nil {
+		// keyFunc was not provided.  short circuiting validation
+		return token, NewValidationError("no Keyfunc was provided.", ValidationErrorUnverifiable)
+	}
+	if key, err = keyFunc(token); err != nil {
+		// keyFunc returned an error
+		if ve, ok := err.(*ValidationError); ok {
+			return token, ve
+		}
+		return token, &ValidationError{Inner: err, Errors: ValidationErrorUnverifiable}
+	}
+
+	vErr := &ValidationError{}
+
+	// Validate Claims
+	if !p.SkipClaimsValidation {
+		if err := token.Claims.Valid(); err != nil {
+
+			// If the Claims Valid returned an error, check if it is a validation error,
+			// If it was another error type, create a ValidationError with a generic ClaimsInvalid flag set
+			if e, ok := err.(*ValidationError); !ok {
+				vErr = &ValidationError{Inner: err, Errors: ValidationErrorClaimsInvalid}
+			} else {
+				vErr = e
+			}
+		}
+	}
+
+	// Perform validation
+	token.Signature = parts[2]
+	if err = token.Method.Verify(strings.Join(parts[0:2], "."), token.Signature, key); err != nil {
+		vErr.Inner = err
+		vErr.Errors |= ValidationErrorSignatureInvalid
+	}
+
+	if vErr.valid() {
+		token.Valid = true
+		return token, nil
+	}
+
+	return token, vErr
+}
+
+// WARNING: Don't use this method unless you know what you're doing
+//
+// This method parses the token but doesn't validate the signature. It's only
+// ever useful in cases where you know the signature is valid (because it has
+// been checked previously in the stack) and you want to extract values from
+// it.
+func (p *Parser) ParseUnverified(tokenString string, claims Claims) (token *Token, parts []string, err error) {
+	parts = strings.Split(tokenString, ".")
+	if len(parts) != 3 {
+		return nil, parts, NewValidationError("token contains an invalid number of segments", ValidationErrorMalformed)
+	}
+
+	token = &Token{Raw: tokenString}
+
+	// parse Header
+	var headerBytes []byte
+	if headerBytes, err = DecodeSegment(parts[0]); err != nil {
+		if strings.HasPrefix(strings.ToLower(tokenString), "bearer ") {
+			return token, parts, NewValidationError("tokenstring should not contain 'bearer '", ValidationErrorMalformed)
+		}
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	if err = json.Unmarshal(headerBytes, &token.Header); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// parse Claims
+	var claimBytes []byte
+	token.Claims = claims
+
+	if claimBytes, err = DecodeSegment(parts[1]); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
+	if p.UseJSONNumber {
+		dec.UseNumber()
+	}
+	// JSON Decode.  Special case for map type to avoid weird pointer behavior
+	if c, ok := token.Claims.(MapClaims); ok {
+		err = dec.Decode(&c)
+	} else {
+		err = dec.Decode(&claims)
+	}
+	// Handle decode error
+	if err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// Lookup signature method
+	if method, ok := token.Header["alg"].(string); ok {
+		if token.Method = GetSigningMethod(method); token.Method == nil {
+			return token, parts, NewValidationError("signing method (alg) is unavailable.", ValidationErrorUnverifiable)
+		}
+	} else {
+		return token, parts, NewValidationError("signing method (alg) is unspecified.", ValidationErrorUnverifiable)
+	}
+
+	return token, parts, nil
+}

vendor/github.com/dgrijalva/jwt-go/rsa.go

@@ -0,0 +1,101 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+// Implements the RSA family of signing methods signing methods
+// Expects *rsa.PrivateKey for signing and *rsa.PublicKey for validation
+type SigningMethodRSA struct {
+	Name string
+	Hash crypto.Hash
+}
+
+// Specific instances for RS256 and company
+var (
+	SigningMethodRS256 *SigningMethodRSA
+	SigningMethodRS384 *SigningMethodRSA
+	SigningMethodRS512 *SigningMethodRSA
+)
+
+func init() {
+	// RS256
+	SigningMethodRS256 = &SigningMethodRSA{"RS256", crypto.SHA256}
+	RegisterSigningMethod(SigningMethodRS256.Alg(), func() SigningMethod {
+		return SigningMethodRS256
+	})
+
+	// RS384
+	SigningMethodRS384 = &SigningMethodRSA{"RS384", crypto.SHA384}
+	RegisterSigningMethod(SigningMethodRS384.Alg(), func() SigningMethod {
+		return SigningMethodRS384
+	})
+
+	// RS512
+	SigningMethodRS512 = &SigningMethodRSA{"RS512", crypto.SHA512}
+	RegisterSigningMethod(SigningMethodRS512.Alg(), func() SigningMethod {
+		return SigningMethodRS512
+	})
+}
+
+func (m *SigningMethodRSA) Alg() string {
+	return m.Name
+}
+
+// Implements the Verify method from SigningMethod
+// For this signing method, must be an *rsa.PublicKey structure.
+func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	var rsaKey *rsa.PublicKey
+	var ok bool
+
+	if rsaKey, ok = key.(*rsa.PublicKey); !ok {
+		return ErrInvalidKeyType
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, must be an *rsa.PrivateKey structure.
+func (m *SigningMethodRSA) Sign(signingString string, key interface{}) (string, error) {
+	var rsaKey *rsa.PrivateKey
+	var ok bool
+
+	// Validate type of key
+	if rsaKey, ok = key.(*rsa.PrivateKey); !ok {
+		return "", ErrInvalidKey
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return the encoded bytes
+	if sigBytes, err := rsa.SignPKCS1v15(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil)); err == nil {
+		return EncodeSegment(sigBytes), nil
+	} else {
+		return "", err
+	}
+}

vendor/github.com/dgrijalva/jwt-go/rsa_pss.go

@@ -0,0 +1,126 @@
+// +build go1.4
+
+package jwt
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+// Implements the RSAPSS family of signing methods signing methods
+type SigningMethodRSAPSS struct {
+	*SigningMethodRSA
+	Options *rsa.PSSOptions
+}
+
+// Specific instances for RS/PS and company
+var (
+	SigningMethodPS256 *SigningMethodRSAPSS
+	SigningMethodPS384 *SigningMethodRSAPSS
+	SigningMethodPS512 *SigningMethodRSAPSS
+)
+
+func init() {
+	// PS256
+	SigningMethodPS256 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS256",
+			Hash: crypto.SHA256,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA256,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS256.Alg(), func() SigningMethod {
+		return SigningMethodPS256
+	})
+
+	// PS384
+	SigningMethodPS384 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS384",
+			Hash: crypto.SHA384,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA384,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS384.Alg(), func() SigningMethod {
+		return SigningMethodPS384
+	})
+
+	// PS512
+	SigningMethodPS512 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS512",
+			Hash: crypto.SHA512,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA512,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS512.Alg(), func() SigningMethod {
+		return SigningMethodPS512
+	})
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an rsa.PublicKey struct
+func (m *SigningMethodRSAPSS) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	var rsaKey *rsa.PublicKey
+	switch k := key.(type) {
+	case *rsa.PublicKey:
+		rsaKey = k
+	default:
+		return ErrInvalidKey
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	return rsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, m.Options)
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an rsa.PrivateKey struct
+func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (string, error) {
+	var rsaKey *rsa.PrivateKey
+
+	switch k := key.(type) {
+	case *rsa.PrivateKey:
+		rsaKey = k
+	default:
+		return "", ErrInvalidKeyType
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return the encoded bytes
+	if sigBytes, err := rsa.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); err == nil {
+		return EncodeSegment(sigBytes), nil
+	} else {
+		return "", err
+	}
+}

vendor/github.com/dgrijalva/jwt-go/rsa_utils.go

@@ -0,0 +1,101 @@
+package jwt
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+)
+
+var (
+	ErrKeyMustBePEMEncoded = errors.New("Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key")
+	ErrNotRSAPrivateKey    = errors.New("Key is not a valid RSA private key")
+	ErrNotRSAPublicKey     = errors.New("Key is not a valid RSA public key")
+)
+
+// Parse PEM encoded PKCS1 or PKCS8 private key
+func ParseRSAPrivateKeyFromPEM(key []byte) (*rsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKCS1PrivateKey(block.Bytes); err != nil {
+		if parsedKey, err = x509.ParsePKCS8PrivateKey(block.Bytes); err != nil {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
+		return nil, ErrNotRSAPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 private key protected with password
+func ParseRSAPrivateKeyFromPEMWithPassword(key []byte, password string) (*rsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	var parsedKey interface{}
+
+	var blockDecrypted []byte
+	if blockDecrypted, err = x509.DecryptPEMBlock(block, []byte(password)); err != nil {
+		return nil, err
+	}
+
+	if parsedKey, err = x509.ParsePKCS1PrivateKey(blockDecrypted); err != nil {
+		if parsedKey, err = x509.ParsePKCS8PrivateKey(blockDecrypted); err != nil {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
+		return nil, ErrNotRSAPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 public key
+func ParseRSAPublicKeyFromPEM(key []byte) (*rsa.PublicKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
+		if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
+			parsedKey = cert.PublicKey
+		} else {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PublicKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PublicKey); !ok {
+		return nil, ErrNotRSAPublicKey
+	}
+
+	return pkey, nil
+}

vendor/github.com/dgrijalva/jwt-go/signing_method.go

@@ -0,0 +1,35 @@
+package jwt
+
+import (
+	"sync"
+)
+
+var signingMethods = map[string]func() SigningMethod{}
+var signingMethodLock = new(sync.RWMutex)
+
+// Implement SigningMethod to add new methods for signing or verifying tokens.
+type SigningMethod interface {
+	Verify(signingString, signature string, key interface{}) error // Returns nil if signature is valid
+	Sign(signingString string, key interface{}) (string, error)    // Returns encoded signature or error
+	Alg() string                                                   // returns the alg identifier for this method (example: 'HS256')
+}
+
+// Register the "alg" name and a factory function for signing method.
+// This is typically done during init() in the method's implementation
+func RegisterSigningMethod(alg string, f func() SigningMethod) {
+	signingMethodLock.Lock()
+	defer signingMethodLock.Unlock()
+
+	signingMethods[alg] = f
+}
+
+// Get a signing method from an "alg" string
+func GetSigningMethod(alg string) (method SigningMethod) {
+	signingMethodLock.RLock()
+	defer signingMethodLock.RUnlock()
+
+	if methodF, ok := signingMethods[alg]; ok {
+		method = methodF()
+	}
+	return
+}

vendor/github.com/dgrijalva/jwt-go/token.go

@@ -0,0 +1,108 @@
+package jwt
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+// TimeFunc provides the current time when parsing token to validate "exp" claim (expiration time).
+// You can override it to use another time value.  This is useful for testing or if your
+// server uses a different time zone than your tokens.
+var TimeFunc = time.Now
+
+// Parse methods use this callback function to supply
+// the key for verification.  The function receives the parsed,
+// but unverified Token.  This allows you to use properties in the
+// Header of the token (such as `kid`) to identify which key to use.
+type Keyfunc func(*Token) (interface{}, error)
+
+// A JWT Token.  Different fields will be used depending on whether you're
+// creating or parsing/verifying a token.
+type Token struct {
+	Raw       string                 // The raw token.  Populated when you Parse a token
+	Method    SigningMethod          // The signing method used or to be used
+	Header    map[string]interface{} // The first segment of the token
+	Claims    Claims                 // The second segment of the token
+	Signature string                 // The third segment of the token.  Populated when you Parse a token
+	Valid     bool                   // Is the token valid?  Populated when you Parse/Verify a token
+}
+
+// Create a new Token.  Takes a signing method
+func New(method SigningMethod) *Token {
+	return NewWithClaims(method, MapClaims{})
+}
+
+func NewWithClaims(method SigningMethod, claims Claims) *Token {
+	return &Token{
+		Header: map[string]interface{}{
+			"typ": "JWT",
+			"alg": method.Alg(),
+		},
+		Claims: claims,
+		Method: method,
+	}
+}
+
+// Get the complete, signed token
+func (t *Token) SignedString(key interface{}) (string, error) {
+	var sig, sstr string
+	var err error
+	if sstr, err = t.SigningString(); err != nil {
+		return "", err
+	}
+	if sig, err = t.Method.Sign(sstr, key); err != nil {
+		return "", err
+	}
+	return strings.Join([]string{sstr, sig}, "."), nil
+}
+
+// Generate the signing string.  This is the
+// most expensive part of the whole deal.  Unless you
+// need this for something special, just go straight for
+// the SignedString.
+func (t *Token) SigningString() (string, error) {
+	var err error
+	parts := make([]string, 2)
+	for i, _ := range parts {
+		var jsonValue []byte
+		if i == 0 {
+			if jsonValue, err = json.Marshal(t.Header); err != nil {
+				return "", err
+			}
+		} else {
+			if jsonValue, err = json.Marshal(t.Claims); err != nil {
+				return "", err
+			}
+		}
+
+		parts[i] = EncodeSegment(jsonValue)
+	}
+	return strings.Join(parts, "."), nil
+}
+
+// Parse, validate, and return a token.
+// keyFunc will receive the parsed token and should return the key for validating.
+// If everything is kosher, err will be nil
+func Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
+	return new(Parser).Parse(tokenString, keyFunc)
+}
+
+func ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
+	return new(Parser).ParseWithClaims(tokenString, claims, keyFunc)
+}
+
+// Encode JWT specific base64url encoding with padding stripped
+func EncodeSegment(seg []byte) string {
+	return strings.TrimRight(base64.URLEncoding.EncodeToString(seg), "=")
+}
+
+// Decode JWT specific base64url encoding with padding stripped
+func DecodeSegment(seg string) ([]byte, error) {
+	if l := len(seg) % 4; l > 0 {
+		seg += strings.Repeat("=", 4-l)
+	}
+
+	return base64.URLEncoding.DecodeString(seg)
+}

vendor/github.com/dsoprea/go-exif/.travis.yml

@@ -0,0 +1,24 @@
+language: go
+go:
+  - master
+  - stable
+  - "1.14"
+  - "1.13"
+  - "1.12"
+env:
+  - GO111MODULE=on
+install:
+  - go get -t ./...
+script:
+# v1
+  - go test -v .
+  - go test -v ./exif-read-tool
+# v2
+  - cd v2
+  - go test -v ./...
+  - cd ..
+# v3. Coverage reports comes from this.
+  - cd v3
+  - go test -v ./... -coverprofile=coverage.txt -covermode=atomic
+after_success:
+  - curl -s https://codecov.io/bash | bash

vendor/github.com/dsoprea/go-exif/LICENSE

@@ -0,0 +1,9 @@
+MIT LICENSE
+
+Copyright 2019 Dustin Oprea
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/dsoprea/go-exif/README.md

@@ -0,0 +1,206 @@
+[![Build Status](https://travis-ci.org/dsoprea/go-exif.svg?branch=master)](https://travis-ci.org/dsoprea/go-exif)
+[![codecov](https://codecov.io/gh/dsoprea/go-exif/branch/master/graph/badge.svg)](https://codecov.io/gh/dsoprea/go-exif)
+[![Go Report Card](https://goreportcard.com/badge/github.com/dsoprea/go-exif/v3)](https://goreportcard.com/report/github.com/dsoprea/go-exif/v3)
+[![GoDoc](https://godoc.org/github.com/dsoprea/go-exif/v3?status.svg)](https://godoc.org/github.com/dsoprea/go-exif/v3)
+
+# Overview
+
+This package provides native Go functionality to parse an existing EXIF block, update an existing EXIF block, or add a new EXIF block.
+
+
+# Getting
+
+To get the project and dependencies:
+
+```
+$ go get -t github.com/dsoprea/go-exif/v3
+```
+
+
+# Scope
+
+This project is concerned only with parsing and encoding raw EXIF data. It does
+not understand specific file-formats. This package assumes you know how to
+extract the raw EXIF data from a file, such as a JPEG, and, if you want to
+update it, know how to write it back. File-specific formats are not the concern
+of *go-exif*, though we provide
+[exif.SearchAndExtractExif][search-and-extract-exif] and
+[exif.SearchFileAndExtractExif][search-file-and-extract-exif] as brute-force
+search mechanisms that will help you explore the EXIF information for newer
+formats that you might not yet have any way to parse.
+
+That said, the author also provides the following projects to support the
+efficient processing of the corresponding image formats:
+
+- [go-jpeg-image-structure](https://github.com/dsoprea/go-jpeg-image-structure)
+- [go-png-image-structure](https://github.com/dsoprea/go-png-image-structure)
+- [go-tiff-image-structure](https://github.com/dsoprea/go-tiff-image-structure)
+- [go-heic-exif-extractor](https://github.com/dsoprea/go-heic-exif-extractor)
+
+See the [SetExif example in go-jpeg-image-structure][jpeg-set-exif] for
+practical information on getting started with JPEG files.
+
+
+# Usage
+
+The package provides a set of [working examples][examples] and is covered by
+unit-tests. Please look to these for getting familiar with how to read and write
+EXIF.
+
+Create an instance of the `Exif` type and call `Scan()` with a byte-slice, where
+the first byte is the beginning of the raw EXIF data. You may pass a callback
+that will be invoked for every tag or `nil` if you do not want one. If no
+callback is given, you are effectively just validating the structure or parsing
+of the image.
+
+Obviously, it is most efficient to properly parse the media file and then
+provide the specific EXIF data to be parsed, but there is also a heuristic for
+finding the EXIF data within the media blob, directly. This means that, at least
+for testing or curiosity, **you do not have to parse or even understand the
+format of image or audio file in order to find and decode the EXIF information
+inside of it.** See the usage of the `SearchAndExtractExif` method in the
+example.
+
+The library often refers to an IFD with an "IFD path" (e.g. IFD/Exif,
+IFD/GPSInfo). A "fully-qualified" IFD-path is one that includes an index
+describing which specific sibling IFD is being referred to if not the first one
+(e.g. IFD1, the IFD where the thumbnail is expressed per the TIFF standard).
+
+There is an "IFD mapping" and a "tag index" that must be created and passed to
+the library from the top. These contain all of the knowledge of the IFD
+hierarchies and their tag-IDs (the IFD mapping) and the tags that they are
+allowed to host (the tag index). There are convenience functions to load them
+with the standard TIFF information, but you, alternatively, may choose
+something totally different (to support parsing any kind of EXIF data that does
+not follow or is not relevant to TIFF at all).
+
+
+# Standards and Customization
+
+This project is configuration driven. By default, it has no knowledge of tags
+and IDs until you load them prior to using (which is incorporated in the
+examples). You are just as easily able to add additional custom IFDs and custom
+tags for them. If desired, you could completely ignore the standard information
+and load *totally* non-standard IFDs and tags.
+
+This would be useful for divergent implementations that add non-standard
+information to images. It would also be useful if there is some need to just
+store a flat list of tags in an image for simplified, proprietary usage.
+
+
+# Reader Tool
+
+There is a runnable reading/dumping tool included:
+
+```
+$ go get github.com/dsoprea/go-exif/v3/command/exif-read-tool
+$ exif-read-tool --filepath "<media file-path>"
+```
+
+Example output:
+
+```
+IFD-PATH=[IFD] ID=(0x010f) NAME=[Make] COUNT=(6) TYPE=[ASCII] VALUE=[Canon]
+IFD-PATH=[IFD] ID=(0x0110) NAME=[Model] COUNT=(22) TYPE=[ASCII] VALUE=[Canon EOS 5D Mark III]
+IFD-PATH=[IFD] ID=(0x0112) NAME=[Orientation] COUNT=(1) TYPE=[SHORT] VALUE=[1]
+IFD-PATH=[IFD] ID=(0x011a) NAME=[XResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD-PATH=[IFD] ID=(0x011b) NAME=[YResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD-PATH=[IFD] ID=(0x0128) NAME=[ResolutionUnit] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD-PATH=[IFD] ID=(0x0132) NAME=[DateTime] COUNT=(20) TYPE=[ASCII] VALUE=[2017:12:02 08:18:50]
+...
+```
+
+You can also print the raw, parsed data as JSON:
+
+```
+$ exif-read-tool --filepath "<media file-path>" -json
+```
+
+Example output:
+
+```
+[
+    {
+        "ifd_path": "IFD",
+        "fq_ifd_path": "IFD",
+        "ifd_index": 0,
+        "tag_id": 271,
+        "tag_name": "Make",
+        "tag_type_id": 2,
+        "tag_type_name": "ASCII",
+        "unit_count": 6,
+        "value": "Canon",
+        "value_string": "Canon"
+    },
+    {
+        "ifd_path": "IFD",
+...
+```
+
+
+# Testing
+
+The traditional method:
+
+```
+$ go test github.com/dsoprea/go-exif/v3/...
+```
+
+
+# Release Notes
+
+## v3 Release
+
+This release primarily introduces an interchangeable data-layer, where any
+`io.ReadSeeker` can be used to read EXIF data rather than necessarily loading
+the EXIF blob into memory first.
+
+Several backwards-incompatible clean-ups were also included in this release. See
+[releases][releases] for more information.
+
+## v2 Release
+
+Features a heavily reflowed interface that makes usage much simpler. The
+undefined-type tag-processing (which affects most photographic images) has also
+been overhauled and streamlined. It is now complete and stable. Adoption is
+strongly encouraged.
+
+
+# *Contributing*
+
+EXIF has an excellently-documented structure but there are a lot of devices and
+manufacturers out there. There are only so many files that we can personally
+find to test against, and most of these are images that have been generated only
+in the past few years. JPEG, being the largest implementor of EXIF, has been
+around for even longer (but not much). Therefore, there is a lot of
+compatibility to test for.
+
+**If you are able to help by running the included reader-tool against all of the
+EXIF-compatible files you have, it would be deeply appreciated. This is mostly
+going to be JPEG files (but not all variations). If you are able to test a large
+number of files (thousands or millions) then please post an issue mentioning how
+many files you have processed. If you had failures, then please share them and
+try to support efforts to understand them.**
+
+If you are able to test 100K+ files, I will give you credit on the project. The
+further back in time your images reach, the higher in the list your name/company
+will go.
+
+
+# Contributors/Testing
+
+Thank you to the following users for solving non-trivial issues, supporting the
+project with solving edge-case problems in specific images, or otherwise
+providing their non-trivial time or image corpus to test go-exif:
+
+- [philip-firstorder](https://github.com/philip-firstorder) (200K images)
+- [matchstick](https://github.com/matchstick) (102K images)
+
+In addition to these, it has been tested on my own collection, north of 478K
+images.
+
+[search-and-extract-exif]: https://godoc.org/github.com/dsoprea/go-exif/v3#SearchAndExtractExif
+[search-file-and-extract-exif]: https://godoc.org/github.com/dsoprea/go-exif/v3#SearchFileAndExtractExif
+[jpeg-set-exif]: https://godoc.org/github.com/dsoprea/go-jpeg-image-structure#example-SegmentList-SetExif
+[examples]: https://godoc.org/github.com/dsoprea/go-exif/v3#pkg-examples
+[releases]: https://github.com/dsoprea/go-exif/releases

vendor/github.com/dsoprea/go-exif/error.go

@@ -0,0 +1,10 @@
+package exif
+
+import (
+	"errors"
+)
+
+var (
+	ErrTagNotFound    = errors.New("tag not found")
+	ErrTagNotStandard = errors.New("tag not a standard tag")
+)

vendor/github.com/dsoprea/go-exif/exif.go

@@ -0,0 +1,247 @@
+package exif
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+
+	"encoding/binary"
+	"io/ioutil"
+
+	"github.com/dsoprea/go-logging"
+)
+
+const (
+	// ExifAddressableAreaStart is the absolute offset in the file that all
+	// offsets are relative to.
+	ExifAddressableAreaStart = uint32(0x0)
+
+	// ExifDefaultFirstIfdOffset is essentially the number of bytes in addition
+	// to `ExifAddressableAreaStart` that you have to move in order to escape
+	// the rest of the header and get to the earliest point where we can put
+	// stuff (which has to be the first IFD). This is the size of the header
+	// sequence containing the two-character byte-order, two-character fixed-
+	// bytes, and the four bytes describing the first-IFD offset.
+	ExifDefaultFirstIfdOffset = uint32(2 + 2 + 4)
+)
+
+var (
+	exifLogger = log.NewLogger("exif.exif")
+
+	// EncodeDefaultByteOrder is the default byte-order for encoding operations.
+	EncodeDefaultByteOrder = binary.BigEndian
+
+	// Default byte order for tests.
+	TestDefaultByteOrder = binary.BigEndian
+
+	BigEndianBoBytes    = [2]byte{'M', 'M'}
+	LittleEndianBoBytes = [2]byte{'I', 'I'}
+
+	ByteOrderLookup = map[[2]byte]binary.ByteOrder{
+		BigEndianBoBytes:    binary.BigEndian,
+		LittleEndianBoBytes: binary.LittleEndian,
+	}
+
+	ByteOrderLookupR = map[binary.ByteOrder][2]byte{
+		binary.BigEndian:    BigEndianBoBytes,
+		binary.LittleEndian: LittleEndianBoBytes,
+	}
+
+	ExifFixedBytesLookup = map[binary.ByteOrder][2]byte{
+		binary.LittleEndian: {0x2a, 0x00},
+		binary.BigEndian:    {0x00, 0x2a},
+	}
+)
+
+var (
+	ErrNoExif          = errors.New("no exif data")
+	ErrExifHeaderError = errors.New("exif header error")
+)
+
+// SearchAndExtractExif returns a slice from the beginning of the EXIF data to
+// end of the file (it's not practical to try and calculate where the data
+// actually ends; it needs to be formally parsed).
+func SearchAndExtractExif(data []byte) (rawExif []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	// Search for the beginning of the EXIF information. The EXIF is near the
+	// beginning of our/most JPEGs, so this has a very low cost.
+
+	foundAt := -1
+	for i := 0; i < len(data); i++ {
+		if _, err := ParseExifHeader(data[i:]); err == nil {
+			foundAt = i
+			break
+		} else if log.Is(err, ErrNoExif) == false {
+			return nil, err
+		}
+	}
+
+	if foundAt == -1 {
+		return nil, ErrNoExif
+	}
+
+	return data[foundAt:], nil
+}
+
+// SearchFileAndExtractExif returns a slice from the beginning of the EXIF data
+// to the end of the file (it's not practical to try and calculate where the
+// data actually ends).
+func SearchFileAndExtractExif(filepath string) (rawExif []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	// Open the file.
+
+	f, err := os.Open(filepath)
+	log.PanicIf(err)
+
+	defer f.Close()
+
+	data, err := ioutil.ReadAll(f)
+	log.PanicIf(err)
+
+	rawExif, err = SearchAndExtractExif(data)
+	log.PanicIf(err)
+
+	return rawExif, nil
+}
+
+type ExifHeader struct {
+	ByteOrder      binary.ByteOrder
+	FirstIfdOffset uint32
+}
+
+func (eh ExifHeader) String() string {
+	return fmt.Sprintf("ExifHeader<BYTE-ORDER=[%v] FIRST-IFD-OFFSET=(0x%02x)>", eh.ByteOrder, eh.FirstIfdOffset)
+}
+
+// ParseExifHeader parses the bytes at the very top of the header.
+//
+// This will panic with ErrNoExif on any data errors so that we can double as
+// an EXIF-detection routine.
+func ParseExifHeader(data []byte) (eh ExifHeader, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Good reference:
+	//
+	//      CIPA DC-008-2016; JEITA CP-3451D
+	//      -> http://www.cipa.jp/std/documents/e/DC-008-Translation-2016-E.pdf
+
+	if len(data) < 2 {
+		exifLogger.Warningf(nil, "Not enough data for EXIF header (1): (%d)", len(data))
+		return eh, ErrNoExif
+	}
+
+	byteOrderBytes := [2]byte{data[0], data[1]}
+
+	byteOrder, found := ByteOrderLookup[byteOrderBytes]
+	if found == false {
+		// exifLogger.Warningf(nil, "EXIF byte-order not recognized: [%v]", byteOrderBytes)
+		return eh, ErrNoExif
+	}
+
+	if len(data) < 4 {
+		exifLogger.Warningf(nil, "Not enough data for EXIF header (2): (%d)", len(data))
+		return eh, ErrNoExif
+	}
+
+	fixedBytes := [2]byte{data[2], data[3]}
+	expectedFixedBytes := ExifFixedBytesLookup[byteOrder]
+	if fixedBytes != expectedFixedBytes {
+		// exifLogger.Warningf(nil, "EXIF header fixed-bytes should be [%v] but are: [%v]", expectedFixedBytes, fixedBytes)
+		return eh, ErrNoExif
+	}
+
+	if len(data) < 2 {
+		exifLogger.Warningf(nil, "Not enough data for EXIF header (3): (%d)", len(data))
+		return eh, ErrNoExif
+	}
+
+	firstIfdOffset := byteOrder.Uint32(data[4:8])
+
+	eh = ExifHeader{
+		ByteOrder:      byteOrder,
+		FirstIfdOffset: firstIfdOffset,
+	}
+
+	return eh, nil
+}
+
+// Visit recursively invokes a callback for every tag.
+func Visit(rootIfdName string, ifdMapping *IfdMapping, tagIndex *TagIndex, exifData []byte, visitor RawTagVisitor) (eh ExifHeader, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	eh, err = ParseExifHeader(exifData)
+	log.PanicIf(err)
+
+	ie := NewIfdEnumerate(ifdMapping, tagIndex, exifData, eh.ByteOrder)
+
+	err = ie.Scan(rootIfdName, eh.FirstIfdOffset, visitor, true)
+	log.PanicIf(err)
+
+	return eh, nil
+}
+
+// Collect recursively builds a static structure of all IFDs and tags.
+func Collect(ifdMapping *IfdMapping, tagIndex *TagIndex, exifData []byte) (eh ExifHeader, index IfdIndex, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	eh, err = ParseExifHeader(exifData)
+	log.PanicIf(err)
+
+	ie := NewIfdEnumerate(ifdMapping, tagIndex, exifData, eh.ByteOrder)
+
+	index, err = ie.Collect(eh.FirstIfdOffset, true)
+	log.PanicIf(err)
+
+	return eh, index, nil
+}
+
+// BuildExifHeader constructs the bytes that go in the very beginning.
+func BuildExifHeader(byteOrder binary.ByteOrder, firstIfdOffset uint32) (headerBytes []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	b := new(bytes.Buffer)
+
+	// This is the point in the data that all offsets are relative to.
+	boBytes := ByteOrderLookupR[byteOrder]
+	_, err = b.WriteString(string(boBytes[:]))
+	log.PanicIf(err)
+
+	fixedBytes := ExifFixedBytesLookup[byteOrder]
+
+	_, err = b.Write(fixedBytes[:])
+	log.PanicIf(err)
+
+	err = binary.Write(b, byteOrder, firstIfdOffset)
+	log.PanicIf(err)
+
+	return b.Bytes(), nil
+}

vendor/github.com/dsoprea/go-exif/go.mod

@@ -0,0 +1,11 @@
+module github.com/dsoprea/go-exif
+
+go 1.13
+
+require (
+	github.com/dsoprea/go-logging v0.0.0-20190624164917-c4f10aab7696
+	github.com/go-errors/errors v1.0.1 // indirect
+	github.com/golang/geo v0.0.0-20190916061304-5b978397cfec
+	golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 // indirect
+	gopkg.in/yaml.v2 v2.2.7
+)

vendor/github.com/dsoprea/go-exif/go.sum

@@ -0,0 +1,14 @@
+github.com/dsoprea/go-logging v0.0.0-20190624164917-c4f10aab7696 h1:VGFnZAcLwPpt1sHlAxml+pGLZz9A2s+K/s1YNhPC91Y=
+github.com/dsoprea/go-logging v0.0.0-20190624164917-c4f10aab7696/go.mod h1:Nm/x2ZUNRW6Fe5C3LxdY1PyZY5wmDv/s5dkPJ/VB3iA=
+github.com/go-errors/errors v1.0.1 h1:LUHzmkK3GUKUrL/1gfBUxAHzcev3apQlezX/+O7ma6w=
+github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
+github.com/golang/geo v0.0.0-20190916061304-5b978397cfec h1:lJwO/92dFXWeXOZdoGXgptLmNLwynMSHUmU6besqtiw=
+github.com/golang/geo v0.0.0-20190916061304-5b978397cfec/go.mod h1:QZ0nwyI2jOfgRAoBvP+ab5aRr7c9x7lhGEJrKvBwjWI=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 h1:efeOvDhwQ29Dj3SdAV/MJf8oukgn+8D8WgaCaRMchF8=
+golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.7 h1:VUgggvou5XRW9mHwD/yXxIYSMtY0zoKQf/v226p2nyo=
+gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

vendor/github.com/dsoprea/go-exif/gps.go

@@ -0,0 +1,56 @@
+package exif
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/golang/geo/s2"
+)
+
+var (
+	ErrGpsCoordinatesNotValid = errors.New("GPS coordinates not valid")
+)
+
+type GpsDegrees struct {
+	Orientation               byte
+	Degrees, Minutes, Seconds float64
+}
+
+func (d GpsDegrees) String() string {
+	return fmt.Sprintf("Degrees<O=[%s] D=(%g) M=(%g) S=(%g)>", string([]byte{d.Orientation}), d.Degrees, d.Minutes, d.Seconds)
+}
+
+func (d GpsDegrees) Decimal() float64 {
+	decimal := float64(d.Degrees) + float64(d.Minutes)/60.0 + float64(d.Seconds)/3600.0
+
+	if d.Orientation == 'S' || d.Orientation == 'W' {
+		return -decimal
+	} else {
+		return decimal
+	}
+}
+
+type GpsInfo struct {
+	Latitude, Longitude GpsDegrees
+	Altitude            int
+	Timestamp           time.Time
+}
+
+func (gi *GpsInfo) String() string {
+	return fmt.Sprintf("GpsInfo<LAT=(%.05f) LON=(%.05f) ALT=(%d) TIME=[%s]>", gi.Latitude.Decimal(), gi.Longitude.Decimal(), gi.Altitude, gi.Timestamp)
+}
+
+func (gi *GpsInfo) S2CellId() s2.CellID {
+	latitude := gi.Latitude.Decimal()
+	longitude := gi.Longitude.Decimal()
+
+	ll := s2.LatLngFromDegrees(latitude, longitude)
+	cellId := s2.CellIDFromLatLng(ll)
+
+	if cellId.IsValid() == false {
+		panic(ErrGpsCoordinatesNotValid)
+	}
+
+	return cellId
+}

vendor/github.com/dsoprea/go-exif/ifd.go

@@ -0,0 +1,407 @@
+package exif
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/dsoprea/go-logging"
+)
+
+const (
+	// IFD names. The paths that we referred to the IFDs with are comprised of
+	// these.
+
+	IfdStandard = "IFD"
+	IfdExif     = "Exif"
+	IfdGps      = "GPSInfo"
+	IfdIop      = "Iop"
+
+	// Tag IDs for child IFDs.
+
+	IfdExifId = 0x8769
+	IfdGpsId  = 0x8825
+	IfdIopId  = 0xA005
+
+	// Just a placeholder.
+
+	IfdRootId = 0x0000
+
+	// The paths of the standard IFDs expressed in the standard IFD-mappings
+	// and as the group-names in the tag data.
+
+	IfdPathStandard        = "IFD"
+	IfdPathStandardExif    = "IFD/Exif"
+	IfdPathStandardExifIop = "IFD/Exif/Iop"
+	IfdPathStandardGps     = "IFD/GPSInfo"
+)
+
+var (
+	ifdLogger = log.NewLogger("exif.ifd")
+)
+
+var (
+	ErrChildIfdNotMapped = errors.New("no child-IFD for that tag-ID under parent")
+)
+
+// type IfdIdentity struct {
+// 	ParentIfdName string
+// 	IfdName       string
+// }
+
+// func (ii IfdIdentity) String() string {
+// 	return fmt.Sprintf("IfdIdentity<PARENT-NAME=[%s] NAME=[%s]>", ii.ParentIfdName, ii.IfdName)
+// }
+
+type MappedIfd struct {
+	ParentTagId uint16
+	Placement   []uint16
+	Path        []string
+
+	Name     string
+	TagId    uint16
+	Children map[uint16]*MappedIfd
+}
+
+func (mi *MappedIfd) String() string {
+	pathPhrase := mi.PathPhrase()
+	return fmt.Sprintf("MappedIfd<(0x%04X) [%s] PATH=[%s]>", mi.TagId, mi.Name, pathPhrase)
+}
+
+func (mi *MappedIfd) PathPhrase() string {
+	return strings.Join(mi.Path, "/")
+}
+
+// IfdMapping describes all of the IFDs that we currently recognize.
+type IfdMapping struct {
+	rootNode *MappedIfd
+}
+
+func NewIfdMapping() (ifdMapping *IfdMapping) {
+	rootNode := &MappedIfd{
+		Path:     make([]string, 0),
+		Children: make(map[uint16]*MappedIfd),
+	}
+
+	return &IfdMapping{
+		rootNode: rootNode,
+	}
+}
+
+func NewIfdMappingWithStandard() (ifdMapping *IfdMapping) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	im := NewIfdMapping()
+
+	err := LoadStandardIfds(im)
+	log.PanicIf(err)
+
+	return im
+}
+
+func (im *IfdMapping) Get(parentPlacement []uint16) (childIfd *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ptr := im.rootNode
+	for _, tagId := range parentPlacement {
+		if descendantPtr, found := ptr.Children[tagId]; found == false {
+			log.Panicf("ifd child with tag-ID (%04x) not registered: [%s]", tagId, ptr.PathPhrase())
+		} else {
+			ptr = descendantPtr
+		}
+	}
+
+	return ptr, nil
+}
+
+func (im *IfdMapping) GetWithPath(pathPhrase string) (mi *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if pathPhrase == "" {
+		log.Panicf("path-phrase is empty")
+	}
+
+	path := strings.Split(pathPhrase, "/")
+	ptr := im.rootNode
+
+	for _, name := range path {
+		var hit *MappedIfd
+		for _, mi := range ptr.Children {
+			if mi.Name == name {
+				hit = mi
+				break
+			}
+		}
+
+		if hit == nil {
+			log.Panicf("ifd child with name [%s] not registered: [%s]", name, ptr.PathPhrase())
+		}
+
+		ptr = hit
+	}
+
+	return ptr, nil
+}
+
+// GetChild is a convenience function to get the child path for a given parent
+// placement and child tag-ID.
+func (im *IfdMapping) GetChild(parentPathPhrase string, tagId uint16) (mi *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	mi, err = im.GetWithPath(parentPathPhrase)
+	log.PanicIf(err)
+
+	for _, childMi := range mi.Children {
+		if childMi.TagId == tagId {
+			return childMi, nil
+		}
+	}
+
+	// Whether or not an IFD is defined in data, such an IFD is not registered
+	// and would be unknown.
+	log.Panic(ErrChildIfdNotMapped)
+	return nil, nil
+}
+
+type IfdTagIdAndIndex struct {
+	Name  string
+	TagId uint16
+	Index int
+}
+
+func (itii IfdTagIdAndIndex) String() string {
+	return fmt.Sprintf("IfdTagIdAndIndex<NAME=[%s] ID=(%04x) INDEX=(%d)>", itii.Name, itii.TagId, itii.Index)
+}
+
+// ResolvePath takes a list of names, which can also be suffixed with indices
+// (to identify the second, third, etc.. sibling IFD) and returns a list of
+// tag-IDs and those indices.
+//
+// Example:
+//
+// - IFD/Exif/Iop
+// - IFD0/Exif/Iop
+//
+// This is the only call that supports adding the numeric indices.
+func (im *IfdMapping) ResolvePath(pathPhrase string) (lineage []IfdTagIdAndIndex, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	pathPhrase = strings.TrimSpace(pathPhrase)
+
+	if pathPhrase == "" {
+		log.Panicf("can not resolve empty path-phrase")
+	}
+
+	path := strings.Split(pathPhrase, "/")
+	lineage = make([]IfdTagIdAndIndex, len(path))
+
+	ptr := im.rootNode
+	empty := IfdTagIdAndIndex{}
+	for i, name := range path {
+		indexByte := name[len(name)-1]
+		index := 0
+		if indexByte >= '0' && indexByte <= '9' {
+			index = int(indexByte - '0')
+			name = name[:len(name)-1]
+		}
+
+		itii := IfdTagIdAndIndex{}
+		for _, mi := range ptr.Children {
+			if mi.Name != name {
+				continue
+			}
+
+			itii.Name = name
+			itii.TagId = mi.TagId
+			itii.Index = index
+
+			ptr = mi
+
+			break
+		}
+
+		if itii == empty {
+			log.Panicf("ifd child with name [%s] not registered: [%s]", name, pathPhrase)
+		}
+
+		lineage[i] = itii
+	}
+
+	return lineage, nil
+}
+
+func (im *IfdMapping) FqPathPhraseFromLineage(lineage []IfdTagIdAndIndex) (fqPathPhrase string) {
+	fqPathParts := make([]string, len(lineage))
+	for i, itii := range lineage {
+		if itii.Index > 0 {
+			fqPathParts[i] = fmt.Sprintf("%s%d", itii.Name, itii.Index)
+		} else {
+			fqPathParts[i] = itii.Name
+		}
+	}
+
+	return strings.Join(fqPathParts, "/")
+}
+
+func (im *IfdMapping) PathPhraseFromLineage(lineage []IfdTagIdAndIndex) (pathPhrase string) {
+	pathParts := make([]string, len(lineage))
+	for i, itii := range lineage {
+		pathParts[i] = itii.Name
+	}
+
+	return strings.Join(pathParts, "/")
+}
+
+// StripPathPhraseIndices returns a non-fully-qualified path-phrase (no
+// indices).
+func (im *IfdMapping) StripPathPhraseIndices(pathPhrase string) (strippedPathPhrase string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	lineage, err := im.ResolvePath(pathPhrase)
+	log.PanicIf(err)
+
+	strippedPathPhrase = im.PathPhraseFromLineage(lineage)
+	return strippedPathPhrase, nil
+}
+
+// Add puts the given IFD at the given position of the tree. The position of the
+// tree is referred to as the placement and is represented by a set of tag-IDs,
+// where the leftmost is the root tag and the tags going to the right are
+// progressive descendants.
+func (im *IfdMapping) Add(parentPlacement []uint16, tagId uint16, name string) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! It would be nicer to provide a list of names in the placement rather than tag-IDs.
+
+	ptr, err := im.Get(parentPlacement)
+	log.PanicIf(err)
+
+	path := make([]string, len(parentPlacement)+1)
+	if len(parentPlacement) > 0 {
+		copy(path, ptr.Path)
+	}
+
+	path[len(path)-1] = name
+
+	placement := make([]uint16, len(parentPlacement)+1)
+	if len(placement) > 0 {
+		copy(placement, ptr.Placement)
+	}
+
+	placement[len(placement)-1] = tagId
+
+	childIfd := &MappedIfd{
+		ParentTagId: ptr.TagId,
+		Path:        path,
+		Placement:   placement,
+		Name:        name,
+		TagId:       tagId,
+		Children:    make(map[uint16]*MappedIfd),
+	}
+
+	if _, found := ptr.Children[tagId]; found == true {
+		log.Panicf("child IFD with tag-ID (%04x) already registered under IFD [%s] with tag-ID (%04x)", tagId, ptr.Name, ptr.TagId)
+	}
+
+	ptr.Children[tagId] = childIfd
+
+	return nil
+}
+
+func (im *IfdMapping) dumpLineages(stack []*MappedIfd, input []string) (output []string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	currentIfd := stack[len(stack)-1]
+
+	output = input
+	for _, childIfd := range currentIfd.Children {
+		stackCopy := make([]*MappedIfd, len(stack)+1)
+
+		copy(stackCopy, stack)
+		stackCopy[len(stack)] = childIfd
+
+		// Add to output, but don't include the obligatory root node.
+		parts := make([]string, len(stackCopy)-1)
+		for i, mi := range stackCopy[1:] {
+			parts[i] = mi.Name
+		}
+
+		output = append(output, strings.Join(parts, "/"))
+
+		output, err = im.dumpLineages(stackCopy, output)
+		log.PanicIf(err)
+	}
+
+	return output, nil
+}
+
+func (im *IfdMapping) DumpLineages() (output []string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	stack := []*MappedIfd{im.rootNode}
+	output = make([]string, 0)
+
+	output, err = im.dumpLineages(stack, output)
+	log.PanicIf(err)
+
+	return output, nil
+}
+
+func LoadStandardIfds(im *IfdMapping) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	err = im.Add([]uint16{}, IfdRootId, IfdStandard)
+	log.PanicIf(err)
+
+	err = im.Add([]uint16{IfdRootId}, IfdExifId, IfdExif)
+	log.PanicIf(err)
+
+	err = im.Add([]uint16{IfdRootId, IfdExifId}, IfdIopId, IfdIop)
+	log.PanicIf(err)
+
+	err = im.Add([]uint16{IfdRootId}, IfdGpsId, IfdGps)
+	log.PanicIf(err)
+
+	return nil
+}

vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go

@@ -0,0 +1,530 @@
+package exif
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+const (
+	// Tag-ID + Tag-Type + Unit-Count + Value/Offset.
+	IfdTagEntrySize = uint32(2 + 2 + 4 + 4)
+)
+
+type ByteWriter struct {
+	b         *bytes.Buffer
+	byteOrder binary.ByteOrder
+}
+
+func NewByteWriter(b *bytes.Buffer, byteOrder binary.ByteOrder) (bw *ByteWriter) {
+	return &ByteWriter{
+		b:         b,
+		byteOrder: byteOrder,
+	}
+}
+
+func (bw ByteWriter) writeAsBytes(value interface{}) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	err = binary.Write(bw.b, bw.byteOrder, value)
+	log.PanicIf(err)
+
+	return nil
+}
+
+func (bw ByteWriter) WriteUint32(value uint32) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	err = bw.writeAsBytes(value)
+	log.PanicIf(err)
+
+	return nil
+}
+
+func (bw ByteWriter) WriteUint16(value uint16) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	err = bw.writeAsBytes(value)
+	log.PanicIf(err)
+
+	return nil
+}
+
+func (bw ByteWriter) WriteFourBytes(value []byte) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	len_ := len(value)
+	if len_ != 4 {
+		log.Panicf("value is not four-bytes: (%d)", len_)
+	}
+
+	_, err = bw.b.Write(value)
+	log.PanicIf(err)
+
+	return nil
+}
+
+// ifdOffsetIterator keeps track of where the next IFD should be written by
+// keeping track of where the offsets start, the data that has been added, and
+// bumping the offset *when* the data is added.
+type ifdDataAllocator struct {
+	offset uint32
+	b      bytes.Buffer
+}
+
+func newIfdDataAllocator(ifdDataAddressableOffset uint32) *ifdDataAllocator {
+	return &ifdDataAllocator{
+		offset: ifdDataAddressableOffset,
+	}
+}
+
+func (ida *ifdDataAllocator) Allocate(value []byte) (offset uint32, err error) {
+	_, err = ida.b.Write(value)
+	log.PanicIf(err)
+
+	offset = ida.offset
+	ida.offset += uint32(len(value))
+
+	return offset, nil
+}
+
+func (ida *ifdDataAllocator) NextOffset() uint32 {
+	return ida.offset
+}
+
+func (ida *ifdDataAllocator) Bytes() []byte {
+	return ida.b.Bytes()
+}
+
+// IfdByteEncoder converts an IB to raw bytes (for writing) while also figuring
+// out all of the allocations and indirection that is required for extended
+// data.
+type IfdByteEncoder struct {
+	// journal holds a list of actions taken while encoding.
+	journal [][3]string
+}
+
+func NewIfdByteEncoder() (ibe *IfdByteEncoder) {
+	return &IfdByteEncoder{
+		journal: make([][3]string, 0),
+	}
+}
+
+func (ibe *IfdByteEncoder) Journal() [][3]string {
+	return ibe.journal
+}
+
+func (ibe *IfdByteEncoder) TableSize(entryCount int) uint32 {
+	// Tag-Count + (Entry-Size * Entry-Count) + Next-IFD-Offset.
+	return uint32(2) + (IfdTagEntrySize * uint32(entryCount)) + uint32(4)
+}
+
+func (ibe *IfdByteEncoder) pushToJournal(where, direction, format string, args ...interface{}) {
+	event := [3]string{
+		direction,
+		where,
+		fmt.Sprintf(format, args...),
+	}
+
+	ibe.journal = append(ibe.journal, event)
+}
+
+// PrintJournal prints a hierarchical representation of the steps taken during
+// encoding.
+func (ibe *IfdByteEncoder) PrintJournal() {
+	maxWhereLength := 0
+	for _, event := range ibe.journal {
+		where := event[1]
+
+		len_ := len(where)
+		if len_ > maxWhereLength {
+			maxWhereLength = len_
+		}
+	}
+
+	level := 0
+	for i, event := range ibe.journal {
+		direction := event[0]
+		where := event[1]
+		message := event[2]
+
+		if direction != ">" && direction != "<" && direction != "-" {
+			log.Panicf("journal operation not valid: [%s]", direction)
+		}
+
+		if direction == "<" {
+			if level <= 0 {
+				log.Panicf("journal operations unbalanced (too many closes)")
+			}
+
+			level--
+		}
+
+		indent := strings.Repeat("  ", level)
+
+		fmt.Printf("%3d %s%s %s: %s\n", i, indent, direction, where, message)
+
+		if direction == ">" {
+			level++
+		}
+	}
+
+	if level != 0 {
+		log.Panicf("journal operations unbalanced (too many opens)")
+	}
+}
+
+// encodeTagToBytes encodes the given tag to a byte stream. If
+// `nextIfdOffsetToWrite` is more than (0), recurse into child IFDs
+// (`nextIfdOffsetToWrite` is required in order for them to know where the its
+// IFD data will be written, in order for them to know the offset of where
+// their allocated-data block will start, which follows right behind).
+func (ibe *IfdByteEncoder) encodeTagToBytes(ib *IfdBuilder, bt *BuilderTag, bw *ByteWriter, ida *ifdDataAllocator, nextIfdOffsetToWrite uint32) (childIfdBlock []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Write tag-ID.
+	err = bw.WriteUint16(bt.tagId)
+	log.PanicIf(err)
+
+	// Works for both values and child IFDs (which have an official size of
+	// LONG).
+	err = bw.WriteUint16(uint16(bt.typeId))
+	log.PanicIf(err)
+
+	// Write unit-count.
+
+	if bt.value.IsBytes() == true {
+		effectiveType := bt.typeId
+		if bt.typeId == TypeUndefined {
+			effectiveType = TypeByte
+		}
+
+		// It's a non-unknown value.Calculate the count of values of
+		// the type that we're writing and the raw bytes for the whole list.
+
+		typeSize := uint32(effectiveType.Size())
+
+		valueBytes := bt.value.Bytes()
+
+		len_ := len(valueBytes)
+		unitCount := uint32(len_) / typeSize
+
+		if _, found := tagsWithoutAlignment[bt.tagId]; found == false {
+			remainder := uint32(len_) % typeSize
+
+			if remainder > 0 {
+				log.Panicf("tag (0x%04x) value of (%d) bytes not evenly divisible by type-size (%d)", bt.tagId, len_, typeSize)
+			}
+		}
+
+		err = bw.WriteUint32(unitCount)
+		log.PanicIf(err)
+
+		// Write four-byte value/offset.
+
+		if len_ > 4 {
+			offset, err := ida.Allocate(valueBytes)
+			log.PanicIf(err)
+
+			err = bw.WriteUint32(offset)
+			log.PanicIf(err)
+		} else {
+			fourBytes := make([]byte, 4)
+			copy(fourBytes, valueBytes)
+
+			err = bw.WriteFourBytes(fourBytes)
+			log.PanicIf(err)
+		}
+	} else {
+		if bt.value.IsIb() == false {
+			log.Panicf("tag value is not a byte-slice but also not a child IB: %v", bt)
+		}
+
+		// Write unit-count (one LONG representing one offset).
+		err = bw.WriteUint32(1)
+		log.PanicIf(err)
+
+		if nextIfdOffsetToWrite > 0 {
+			var err error
+
+			ibe.pushToJournal("encodeTagToBytes", ">", "[%s]->[%s]", ib.ifdPath, bt.value.Ib().ifdPath)
+
+			// Create the block of IFD data and everything it requires.
+			childIfdBlock, err = ibe.encodeAndAttachIfd(bt.value.Ib(), nextIfdOffsetToWrite)
+			log.PanicIf(err)
+
+			ibe.pushToJournal("encodeTagToBytes", "<", "[%s]->[%s]", bt.value.Ib().ifdPath, ib.ifdPath)
+
+			// Use the next-IFD offset for it. The IFD will actually get
+			// attached after we return.
+			err = bw.WriteUint32(nextIfdOffsetToWrite)
+			log.PanicIf(err)
+
+		} else {
+			// No child-IFDs are to be allocated. Finish the entry with a NULL
+			// pointer.
+
+			ibe.pushToJournal("encodeTagToBytes", "-", "*Not* descending to child: [%s]", bt.value.Ib().ifdPath)
+
+			err = bw.WriteUint32(0)
+			log.PanicIf(err)
+		}
+	}
+
+	return childIfdBlock, nil
+}
+
+// encodeIfdToBytes encodes the given IB to a byte-slice. We are given the
+// offset at which this IFD will be written. This method is used called both to
+// pre-determine how big the table is going to be (so that we can calculate the
+// address to allocate data at) as well as to write the final table.
+//
+// It is necessary to fully realize the table in order to predetermine its size
+// because it is not enough to know the size of the table: If there are child
+// IFDs, we will not be able to allocate them without first knowing how much
+// data we need to allocate for the current IFD.
+func (ibe *IfdByteEncoder) encodeIfdToBytes(ib *IfdBuilder, ifdAddressableOffset uint32, nextIfdOffsetToWrite uint32, setNextIb bool) (data []byte, tableSize uint32, dataSize uint32, childIfdSizes []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ibe.pushToJournal("encodeIfdToBytes", ">", "%s", ib)
+
+	tableSize = ibe.TableSize(len(ib.tags))
+
+	b := new(bytes.Buffer)
+	bw := NewByteWriter(b, ib.byteOrder)
+
+	// Write tag count.
+	err = bw.WriteUint16(uint16(len(ib.tags)))
+	log.PanicIf(err)
+
+	ida := newIfdDataAllocator(ifdAddressableOffset)
+
+	childIfdBlocks := make([][]byte, 0)
+
+	// Write raw bytes for each tag entry. Allocate larger data to be referred
+	// to in the follow-up data-block as required. Any "unknown"-byte tags that
+	// we can't parse will not be present here (using AddTagsFromExisting(), at
+	// least).
+	for _, bt := range ib.tags {
+		childIfdBlock, err := ibe.encodeTagToBytes(ib, bt, bw, ida, nextIfdOffsetToWrite)
+		log.PanicIf(err)
+
+		if childIfdBlock != nil {
+			// We aren't allowed to have non-nil child IFDs if we're just
+			// sizing things up.
+			if nextIfdOffsetToWrite == 0 {
+				log.Panicf("no IFD offset provided for child-IFDs; no new child-IFDs permitted")
+			}
+
+			nextIfdOffsetToWrite += uint32(len(childIfdBlock))
+			childIfdBlocks = append(childIfdBlocks, childIfdBlock)
+		}
+	}
+
+	dataBytes := ida.Bytes()
+	dataSize = uint32(len(dataBytes))
+
+	childIfdSizes = make([]uint32, len(childIfdBlocks))
+	childIfdsTotalSize := uint32(0)
+	for i, childIfdBlock := range childIfdBlocks {
+		len_ := uint32(len(childIfdBlock))
+		childIfdSizes[i] = len_
+		childIfdsTotalSize += len_
+	}
+
+	// N the link from this IFD to the next IFD that will be written in the
+	// next cycle.
+	if setNextIb == true {
+		// Write address of next IFD in chain. This will be the original
+		// allocation offset plus the size of everything we have allocated for
+		// this IFD and its child-IFDs.
+		//
+		// It is critical that this number is stepped properly. We experienced
+		// an issue whereby it first looked like we were duplicating the IFD and
+		// then that we were duplicating the tags in the wrong IFD, and then
+		// finally we determined that the next-IFD offset for the first IFD was
+		// accidentally pointing back to the EXIF IFD, so we were visiting it
+		// twice when visiting through the tags after decoding. It was an
+		// expensive bug to find.
+
+		ibe.pushToJournal("encodeIfdToBytes", "-", "Setting 'next' IFD to (0x%08x).", nextIfdOffsetToWrite)
+
+		err := bw.WriteUint32(nextIfdOffsetToWrite)
+		log.PanicIf(err)
+	} else {
+		err := bw.WriteUint32(0)
+		log.PanicIf(err)
+	}
+
+	_, err = b.Write(dataBytes)
+	log.PanicIf(err)
+
+	// Append any child IFD blocks after our table and data blocks. These IFDs
+	// were equipped with the appropriate offset information so it's expected
+	// that all offsets referred to by these will be correct.
+	//
+	// Note that child-IFDs are append after the current IFD and before the
+	// next IFD, as opposed to the root IFDs, which are chained together but
+	// will be interrupted by these child-IFDs (which is expected, per the
+	// standard).
+
+	for _, childIfdBlock := range childIfdBlocks {
+		_, err = b.Write(childIfdBlock)
+		log.PanicIf(err)
+	}
+
+	ibe.pushToJournal("encodeIfdToBytes", "<", "%s", ib)
+
+	return b.Bytes(), tableSize, dataSize, childIfdSizes, nil
+}
+
+// encodeAndAttachIfd is a reentrant function that processes the IFD chain.
+func (ibe *IfdByteEncoder) encodeAndAttachIfd(ib *IfdBuilder, ifdAddressableOffset uint32) (data []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ibe.pushToJournal("encodeAndAttachIfd", ">", "%s", ib)
+
+	b := new(bytes.Buffer)
+
+	i := 0
+
+	for thisIb := ib; thisIb != nil; thisIb = thisIb.nextIb {
+
+		// Do a dry-run in order to pre-determine its size requirement.
+
+		ibe.pushToJournal("encodeAndAttachIfd", ">", "Beginning encoding process: (%d) [%s]", i, thisIb.ifdPath)
+
+		ibe.pushToJournal("encodeAndAttachIfd", ">", "Calculating size: (%d) [%s]", i, thisIb.ifdPath)
+
+		_, tableSize, allocatedDataSize, _, err := ibe.encodeIfdToBytes(thisIb, ifdAddressableOffset, 0, false)
+		log.PanicIf(err)
+
+		ibe.pushToJournal("encodeAndAttachIfd", "<", "Finished calculating size: (%d) [%s]", i, thisIb.ifdPath)
+
+		ifdAddressableOffset += tableSize
+		nextIfdOffsetToWrite := ifdAddressableOffset + allocatedDataSize
+
+		ibe.pushToJournal("encodeAndAttachIfd", ">", "Next IFD will be written at offset (0x%08x)", nextIfdOffsetToWrite)
+
+		// Write our IFD as well as any child-IFDs (now that we know the offset
+		// where new IFDs and their data will be allocated).
+
+		setNextIb := thisIb.nextIb != nil
+
+		ibe.pushToJournal("encodeAndAttachIfd", ">", "Encoding starting: (%d) [%s] NEXT-IFD-OFFSET-TO-WRITE=(0x%08x)", i, thisIb.ifdPath, nextIfdOffsetToWrite)
+
+		tableAndAllocated, effectiveTableSize, effectiveAllocatedDataSize, childIfdSizes, err :=
+			ibe.encodeIfdToBytes(thisIb, ifdAddressableOffset, nextIfdOffsetToWrite, setNextIb)
+
+		log.PanicIf(err)
+
+		if effectiveTableSize != tableSize {
+			log.Panicf("written table size does not match the pre-calculated table size: (%d) != (%d) %s", effectiveTableSize, tableSize, ib)
+		} else if effectiveAllocatedDataSize != allocatedDataSize {
+			log.Panicf("written allocated-data size does not match the pre-calculated allocated-data size: (%d) != (%d) %s", effectiveAllocatedDataSize, allocatedDataSize, ib)
+		}
+
+		ibe.pushToJournal("encodeAndAttachIfd", "<", "Encoding done: (%d) [%s]", i, thisIb.ifdPath)
+
+		totalChildIfdSize := uint32(0)
+		for _, childIfdSize := range childIfdSizes {
+			totalChildIfdSize += childIfdSize
+		}
+
+		if len(tableAndAllocated) != int(tableSize+allocatedDataSize+totalChildIfdSize) {
+			log.Panicf("IFD table and data is not a consistent size: (%d) != (%d)", len(tableAndAllocated), tableSize+allocatedDataSize+totalChildIfdSize)
+		}
+
+		// TODO(dustin): We might want to verify the original tableAndAllocated length, too.
+
+		_, err = b.Write(tableAndAllocated)
+		log.PanicIf(err)
+
+		// Advance past what we've allocated, thus far.
+
+		ifdAddressableOffset += allocatedDataSize + totalChildIfdSize
+
+		ibe.pushToJournal("encodeAndAttachIfd", "<", "Finishing encoding process: (%d) [%s] [FINAL:] NEXT-IFD-OFFSET-TO-WRITE=(0x%08x)", i, ib.ifdPath, nextIfdOffsetToWrite)
+
+		i++
+	}
+
+	ibe.pushToJournal("encodeAndAttachIfd", "<", "%s", ib)
+
+	return b.Bytes(), nil
+}
+
+// EncodeToExifPayload is the base encoding step that transcribes the entire IB
+// structure to its on-disk layout.
+func (ibe *IfdByteEncoder) EncodeToExifPayload(ib *IfdBuilder) (data []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	data, err = ibe.encodeAndAttachIfd(ib, ExifDefaultFirstIfdOffset)
+	log.PanicIf(err)
+
+	return data, nil
+}
+
+// EncodeToExif calls EncodeToExifPayload and then packages the result into a
+// complete EXIF block.
+func (ibe *IfdByteEncoder) EncodeToExif(ib *IfdBuilder) (data []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	encodedIfds, err := ibe.EncodeToExifPayload(ib)
+	log.PanicIf(err)
+
+	// Wrap the IFD in a formal EXIF block.
+
+	b := new(bytes.Buffer)
+
+	headerBytes, err := BuildExifHeader(ib.byteOrder, ExifDefaultFirstIfdOffset)
+	log.PanicIf(err)
+
+	_, err = b.Write(headerBytes)
+	log.PanicIf(err)
+
+	_, err = b.Write(encodedIfds)
+	log.PanicIf(err)
+
+	return b.Bytes(), nil
+}

vendor/github.com/dsoprea/go-exif/ifd_tag_entry.go

@@ -0,0 +1,233 @@
+package exif
+
+import (
+	"fmt"
+	"reflect"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	iteLogger = log.NewLogger("exif.ifd_tag_entry")
+)
+
+type IfdTagEntry struct {
+	TagId          uint16
+	TagIndex       int
+	TagType        TagTypePrimitive
+	UnitCount      uint32
+	ValueOffset    uint32
+	RawValueOffset []byte
+
+	// ChildIfdName is the right most atom in the IFD-path. We need this to
+	// construct the fully-qualified IFD-path.
+	ChildIfdName string
+
+	// ChildIfdPath is the IFD-path of the child if this tag represents a child
+	// IFD.
+	ChildIfdPath string
+
+	// ChildFqIfdPath is the IFD-path of the child if this tag represents a
+	// child IFD. Includes indices.
+	ChildFqIfdPath string
+
+	// TODO(dustin): !! IB's host the child-IBs directly in the tag, but that's not the case here. Refactor to accomodate it for a consistent experience.
+
+	// IfdPath is the IFD that this tag belongs to.
+	IfdPath string
+
+	// TODO(dustin): !! We now parse and read the value immediately. Update the rest of the logic to use this and get rid of all of the staggered and different resolution mechanisms.
+	value              []byte
+	isUnhandledUnknown bool
+}
+
+func (ite *IfdTagEntry) String() string {
+	return fmt.Sprintf("IfdTagEntry<TAG-IFD-PATH=[%s] TAG-ID=(0x%04x) TAG-TYPE=[%s] UNIT-COUNT=(%d)>", ite.IfdPath, ite.TagId, TypeNames[ite.TagType], ite.UnitCount)
+}
+
+// TODO(dustin): TODO(dustin): Stop exporting IfdPath and TagId.
+//
+// func (ite *IfdTagEntry) IfdPath() string {
+// 	return ite.IfdPath
+// }
+
+// TODO(dustin): TODO(dustin): Stop exporting IfdPath and TagId.
+//
+// func (ite *IfdTagEntry) TagId() uint16 {
+// 	return ite.TagId
+// }
+
+// ValueString renders a string from whatever the value in this tag is.
+func (ite *IfdTagEntry) ValueString(addressableData []byte, byteOrder binary.ByteOrder) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	valueContext :=
+		newValueContextFromTag(
+			ite,
+			addressableData,
+			byteOrder)
+
+	if ite.TagType == TypeUndefined {
+		valueRaw, err := valueContext.Undefined()
+		log.PanicIf(err)
+
+		value = fmt.Sprintf("%v", valueRaw)
+	} else {
+		value, err = valueContext.Format()
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// ValueBytes renders a specific list of bytes from the value in this tag.
+func (ite *IfdTagEntry) ValueBytes(addressableData []byte, byteOrder binary.ByteOrder) (value []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Return the exact bytes of the unknown-type value. Returning a string
+	// (`ValueString`) is easy because we can just pass everything to
+	// `Sprintf()`. Returning the raw, typed value (`Value`) is easy
+	// (obviously). However, here, in order to produce the list of bytes, we
+	// need to coerce whatever `Undefined()` returns.
+	if ite.TagType == TypeUndefined {
+		valueContext :=
+			newValueContextFromTag(
+				ite,
+				addressableData,
+				byteOrder)
+
+		value, err := valueContext.Undefined()
+		log.PanicIf(err)
+
+		switch value.(type) {
+		case []byte:
+			return value.([]byte), nil
+		case TagUnknownType_UnknownValue:
+			b := []byte(value.(TagUnknownType_UnknownValue))
+			return b, nil
+		case string:
+			return []byte(value.(string)), nil
+		case UnknownTagValue:
+			valueBytes, err := value.(UnknownTagValue).ValueBytes()
+			log.PanicIf(err)
+
+			return valueBytes, nil
+		default:
+			// TODO(dustin): !! Finish translating the rest of the types (make reusable and replace into other similar implementations?)
+			log.Panicf("can not produce bytes for unknown-type tag (0x%04x) (2): [%s]", ite.TagId, reflect.TypeOf(value))
+		}
+	}
+
+	originalType := NewTagType(ite.TagType, byteOrder)
+	byteCount := uint32(originalType.Type().Size()) * ite.UnitCount
+
+	tt := NewTagType(TypeByte, byteOrder)
+
+	if tt.valueIsEmbedded(byteCount) == true {
+		iteLogger.Debugf(nil, "Reading BYTE value (ITE; embedded).")
+
+		// In this case, the bytes normally used for the offset are actually
+		// data.
+		value, err = tt.ParseBytes(ite.RawValueOffset, byteCount)
+		log.PanicIf(err)
+	} else {
+		iteLogger.Debugf(nil, "Reading BYTE value (ITE; at offset).")
+
+		value, err = tt.ParseBytes(addressableData[ite.ValueOffset:], byteCount)
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// Value returns the specific, parsed, typed value from the tag.
+func (ite *IfdTagEntry) Value(addressableData []byte, byteOrder binary.ByteOrder) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	valueContext :=
+		newValueContextFromTag(
+			ite,
+			addressableData,
+			byteOrder)
+
+	if ite.TagType == TypeUndefined {
+		value, err = valueContext.Undefined()
+		log.PanicIf(err)
+	} else {
+		tt := NewTagType(ite.TagType, byteOrder)
+
+		value, err = tt.Resolve(valueContext)
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// IfdTagEntryValueResolver instances know how to resolve the values for any
+// tag for a particular EXIF block.
+type IfdTagEntryValueResolver struct {
+	addressableData []byte
+	byteOrder       binary.ByteOrder
+}
+
+func NewIfdTagEntryValueResolver(exifData []byte, byteOrder binary.ByteOrder) (itevr *IfdTagEntryValueResolver) {
+	return &IfdTagEntryValueResolver{
+		addressableData: exifData[ExifAddressableAreaStart:],
+		byteOrder:       byteOrder,
+	}
+}
+
+// ValueBytes will resolve embedded or allocated data from the tag and return the raw bytes.
+func (itevr *IfdTagEntryValueResolver) ValueBytes(ite *IfdTagEntry) (value []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// OBSOLETE(dustin): This is now redundant. Use `(*ValueContext).readRawEncoded()` instead of this method.
+
+	valueContext := newValueContextFromTag(
+		ite,
+		itevr.addressableData,
+		itevr.byteOrder)
+
+	rawBytes, err := valueContext.readRawEncoded()
+	log.PanicIf(err)
+
+	return rawBytes, nil
+}
+
+func (itevr *IfdTagEntryValueResolver) Value(ite *IfdTagEntry) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// OBSOLETE(dustin): This is now redundant. Use `(*ValueContext).Values()` instead of this method.
+
+	valueContext := newValueContextFromTag(
+		ite,
+		itevr.addressableData,
+		itevr.byteOrder)
+
+	values, err := valueContext.Values()
+	log.PanicIf(err)
+
+	return values, nil
+}

vendor/github.com/dsoprea/go-exif/package.go

@@ -0,0 +1,4 @@
+// exif parses raw EXIF information given a block of raw EXIF data.
+//
+// v1 of go-exif is now deprecated. Please use v2.
+package exif

vendor/github.com/dsoprea/go-exif/parser.go

@@ -0,0 +1,190 @@
+package exif
+
+import (
+	"bytes"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+type Parser struct {
+}
+
+func (p *Parser) ParseBytes(data []byte, unitCount uint32) (value []uint8, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeByte.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = []uint8(data[:count])
+
+	return value, nil
+}
+
+// ParseAscii returns a string and auto-strips the trailing NUL character.
+func (p *Parser) ParseAscii(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	if len(data) == 0 || data[count-1] != 0 {
+		s := string(data[:count])
+		typeLogger.Warningf(nil, "ascii not terminated with nul as expected: [%v]", s)
+
+		return s, nil
+	} else {
+		// Auto-strip the NUL from the end. It serves no purpose outside of
+		// encoding semantics.
+
+		return string(data[:count-1]), nil
+	}
+}
+
+// ParseAsciiNoNul returns a string without any consideration for a trailing NUL
+// character.
+func (p *Parser) ParseAsciiNoNul(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	return string(data[:count]), nil
+}
+
+func (p *Parser) ParseShorts(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeShort.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint16, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint16(data[i*2:])
+	}
+
+	return value, nil
+}
+
+func (p *Parser) ParseLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint32, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint32(data[i*4:])
+	}
+
+	return value, nil
+}
+
+func (p *Parser) ParseRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]Rational, count)
+	for i := 0; i < count; i++ {
+		value[i].Numerator = byteOrder.Uint32(data[i*8:])
+		value[i].Denominator = byteOrder.Uint32(data[i*8+4:])
+	}
+
+	return value, nil
+}
+
+func (p *Parser) ParseSignedLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]int32, count)
+	for i := 0; i < count; i++ {
+		err := binary.Read(b, byteOrder, &value[i])
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+func (p *Parser) ParseSignedRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]SignedRational, count)
+	for i := 0; i < count; i++ {
+		err = binary.Read(b, byteOrder, &value[i].Numerator)
+		log.PanicIf(err)
+
+		err = binary.Read(b, byteOrder, &value[i].Denominator)
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}

vendor/github.com/dsoprea/go-exif/tag_type.go

@@ -0,0 +1,397 @@
+package exif
+
+// NOTE(dustin): Most of this file encapsulates deprecated functionality and awaits being dumped in a future release.
+
+import (
+	"fmt"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+type TagType struct {
+	tagType   TagTypePrimitive
+	name      string
+	byteOrder binary.ByteOrder
+}
+
+func NewTagType(tagType TagTypePrimitive, byteOrder binary.ByteOrder) TagType {
+	name, found := TypeNames[tagType]
+	if found == false {
+		log.Panicf("tag-type not valid: 0x%04x", tagType)
+	}
+
+	return TagType{
+		tagType:   tagType,
+		name:      name,
+		byteOrder: byteOrder,
+	}
+}
+
+func (tt TagType) String() string {
+	return fmt.Sprintf("TagType<NAME=[%s]>", tt.name)
+}
+
+func (tt TagType) Name() string {
+	return tt.name
+}
+
+func (tt TagType) Type() TagTypePrimitive {
+	return tt.tagType
+}
+
+func (tt TagType) ByteOrder() binary.ByteOrder {
+	return tt.byteOrder
+}
+
+func (tt TagType) Size() int {
+
+	// DEPRECATED(dustin): `(TagTypePrimitive).Size()` should be used, directly.
+
+	return tt.Type().Size()
+}
+
+// valueIsEmbedded will return a boolean indicating whether the value should be
+// found directly within the IFD entry or an offset to somewhere else.
+func (tt TagType) valueIsEmbedded(unitCount uint32) bool {
+	return (tt.tagType.Size() * int(unitCount)) <= 4
+}
+
+func (tt TagType) readRawEncoded(valueContext ValueContext) (rawBytes []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	unitSizeRaw := uint32(tt.tagType.Size())
+
+	if tt.valueIsEmbedded(valueContext.UnitCount()) == true {
+		byteLength := unitSizeRaw * valueContext.UnitCount()
+		return valueContext.RawValueOffset()[:byteLength], nil
+	} else {
+		return valueContext.AddressableData()[valueContext.ValueOffset() : valueContext.ValueOffset()+valueContext.UnitCount()*unitSizeRaw], nil
+	}
+}
+
+func (tt TagType) ParseBytes(data []byte, unitCount uint32) (value []uint8, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseBytes()` should be used.
+
+	value, err = parser.ParseBytes(data, unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ParseAscii returns a string and auto-strips the trailing NUL character.
+func (tt TagType) ParseAscii(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseAscii()` should be used.
+
+	value, err = parser.ParseAscii(data, unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ParseAsciiNoNul returns a string without any consideration for a trailing NUL
+// character.
+func (tt TagType) ParseAsciiNoNul(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseAsciiNoNul()` should be used.
+
+	value, err = parser.ParseAsciiNoNul(data, unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ParseShorts(data []byte, unitCount uint32) (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseShorts()` should be used.
+
+	value, err = parser.ParseShorts(data, unitCount, tt.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ParseLongs(data []byte, unitCount uint32) (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseLongs()` should be used.
+
+	value, err = parser.ParseLongs(data, unitCount, tt.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ParseRationals(data []byte, unitCount uint32) (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseRationals()` should be used.
+
+	value, err = parser.ParseRationals(data, unitCount, tt.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ParseSignedLongs(data []byte, unitCount uint32) (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseSignedLongs()` should be used.
+
+	value, err = parser.ParseSignedLongs(data, unitCount, tt.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ParseSignedRationals(data []byte, unitCount uint32) (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(*Parser).ParseSignedRationals()` should be used.
+
+	value, err = parser.ParseSignedRationals(data, unitCount, tt.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadByteValues(valueContext ValueContext) (value []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadBytes()` should be used.
+
+	value, err = valueContext.ReadBytes()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadAsciiValue(valueContext ValueContext) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadAscii()` should be used.
+
+	value, err = valueContext.ReadAscii()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadAsciiNoNulValue(valueContext ValueContext) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadAsciiNoNul()` should be used.
+
+	value, err = valueContext.ReadAsciiNoNul()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadShortValues(valueContext ValueContext) (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadShorts()` should be used.
+
+	value, err = valueContext.ReadShorts()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadLongValues(valueContext ValueContext) (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadLongs()` should be used.
+
+	value, err = valueContext.ReadLongs()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadRationalValues(valueContext ValueContext) (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadRationals()` should be used.
+
+	value, err = valueContext.ReadRationals()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadSignedLongValues(valueContext ValueContext) (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadSignedLongs()` should be used.
+
+	value, err = valueContext.ReadSignedLongs()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+func (tt TagType) ReadSignedRationalValues(valueContext ValueContext) (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).ReadSignedRationals()` should be used.
+
+	value, err = valueContext.ReadSignedRationals()
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ResolveAsString resolves the given value and returns a flat string.
+//
+// Where the type is not ASCII, `justFirst` indicates whether to just stringify
+// the first item in the slice (or return an empty string if the slice is
+// empty).
+//
+// Since this method lacks the information to process unknown-type tags (e.g.
+// byte-order, tag-ID, IFD type), it will return an error if attempted. See
+// `Undefined()`.
+func (tt TagType) ResolveAsString(valueContext ValueContext, justFirst bool) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if justFirst == true {
+		value, err = valueContext.FormatFirst()
+		log.PanicIf(err)
+	} else {
+		value, err = valueContext.Format()
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// Resolve knows how to resolve the given value.
+//
+// Since this method lacks the information to process unknown-type tags (e.g.
+// byte-order, tag-ID, IFD type), it will return an error if attempted. See
+// `Undefined()`.
+func (tt TagType) Resolve(valueContext *ValueContext) (values interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `(ValueContext).Values()` should be used.
+
+	values, err = valueContext.Values()
+	log.PanicIf(err)
+
+	return values, nil
+}
+
+// Encode knows how to encode the given value to a byte slice.
+func (tt TagType) Encode(value interface{}) (encoded []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ve := NewValueEncoder(tt.byteOrder)
+
+	ed, err := ve.EncodeWithType(tt, value)
+	log.PanicIf(err)
+
+	return ed.Encoded, err
+}
+
+func (tt TagType) FromString(valueString string) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// DEPRECATED(dustin): `EncodeStringToBytes()` should be used.
+
+	value, err = EncodeStringToBytes(tt.tagType, valueString)
+	log.PanicIf(err)
+
+	return value, nil
+}

vendor/github.com/dsoprea/go-exif/tags.go

@@ -0,0 +1,229 @@
+package exif
+
+import (
+	"fmt"
+
+	"github.com/dsoprea/go-logging"
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	// IFD1
+
+	ThumbnailOffsetTagId = 0x0201
+	ThumbnailSizeTagId   = 0x0202
+
+	// Exif
+
+	TagVersionId = 0x0000
+
+	TagLatitudeId     = 0x0002
+	TagLatitudeRefId  = 0x0001
+	TagLongitudeId    = 0x0004
+	TagLongitudeRefId = 0x0003
+
+	TagTimestampId = 0x0007
+	TagDatestampId = 0x001d
+
+	TagAltitudeId    = 0x0006
+	TagAltitudeRefId = 0x0005
+)
+
+var (
+	// tagsWithoutAlignment is a tag-lookup for tags whose value size won't
+	// necessarily be a multiple of its tag-type.
+	tagsWithoutAlignment = map[uint16]struct{}{
+		// The thumbnail offset is stored as a long, but its data is a binary
+		// blob (not a slice of longs).
+		ThumbnailOffsetTagId: {},
+	}
+)
+
+var (
+	tagsLogger = log.NewLogger("exif.tags")
+)
+
+// File structures.
+
+type encodedTag struct {
+	// id is signed, here, because YAML doesn't have enough information to
+	// support unsigned.
+	Id       int    `yaml:"id"`
+	Name     string `yaml:"name"`
+	TypeName string `yaml:"type_name"`
+}
+
+// Indexing structures.
+
+type IndexedTag struct {
+	Id      uint16
+	Name    string
+	IfdPath string
+	Type    TagTypePrimitive
+}
+
+func (it *IndexedTag) String() string {
+	return fmt.Sprintf("TAG<ID=(0x%04x) NAME=[%s] IFD=[%s]>", it.Id, it.Name, it.IfdPath)
+}
+
+func (it *IndexedTag) IsName(ifdPath, name string) bool {
+	return it.Name == name && it.IfdPath == ifdPath
+}
+
+func (it *IndexedTag) Is(ifdPath string, id uint16) bool {
+	return it.Id == id && it.IfdPath == ifdPath
+}
+
+type TagIndex struct {
+	tagsByIfd  map[string]map[uint16]*IndexedTag
+	tagsByIfdR map[string]map[string]*IndexedTag
+}
+
+func NewTagIndex() *TagIndex {
+	ti := new(TagIndex)
+
+	ti.tagsByIfd = make(map[string]map[uint16]*IndexedTag)
+	ti.tagsByIfdR = make(map[string]map[string]*IndexedTag)
+
+	return ti
+}
+
+func (ti *TagIndex) Add(it *IndexedTag) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Store by ID.
+
+	family, found := ti.tagsByIfd[it.IfdPath]
+	if found == false {
+		family = make(map[uint16]*IndexedTag)
+		ti.tagsByIfd[it.IfdPath] = family
+	}
+
+	if _, found := family[it.Id]; found == true {
+		log.Panicf("tag-ID defined more than once for IFD [%s]: (%02x)", it.IfdPath, it.Id)
+	}
+
+	family[it.Id] = it
+
+	// Store by name.
+
+	familyR, found := ti.tagsByIfdR[it.IfdPath]
+	if found == false {
+		familyR = make(map[string]*IndexedTag)
+		ti.tagsByIfdR[it.IfdPath] = familyR
+	}
+
+	if _, found := familyR[it.Name]; found == true {
+		log.Panicf("tag-name defined more than once for IFD [%s]: (%s)", it.IfdPath, it.Name)
+	}
+
+	familyR[it.Name] = it
+
+	return nil
+}
+
+// Get returns information about the non-IFD tag.
+func (ti *TagIndex) Get(ifdPath string, id uint16) (it *IndexedTag, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if len(ti.tagsByIfd) == 0 {
+		err := LoadStandardTags(ti)
+		log.PanicIf(err)
+	}
+
+	family, found := ti.tagsByIfd[ifdPath]
+	if found == false {
+		log.Panic(ErrTagNotFound)
+	}
+
+	it, found = family[id]
+	if found == false {
+		log.Panic(ErrTagNotFound)
+	}
+
+	return it, nil
+}
+
+// Get returns information about the non-IFD tag.
+func (ti *TagIndex) GetWithName(ifdPath string, name string) (it *IndexedTag, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if len(ti.tagsByIfdR) == 0 {
+		err := LoadStandardTags(ti)
+		log.PanicIf(err)
+	}
+
+	it, found := ti.tagsByIfdR[ifdPath][name]
+	if found != true {
+		log.Panic(ErrTagNotFound)
+	}
+
+	return it, nil
+}
+
+// LoadStandardTags registers the tags that all devices/applications should
+// support.
+func LoadStandardTags(ti *TagIndex) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Read static data.
+
+	encodedIfds := make(map[string][]encodedTag)
+
+	err = yaml.Unmarshal([]byte(tagsYaml), encodedIfds)
+	log.PanicIf(err)
+
+	// Load structure.
+
+	count := 0
+	for ifdPath, tags := range encodedIfds {
+		for _, tagInfo := range tags {
+			tagId := uint16(tagInfo.Id)
+			tagName := tagInfo.Name
+			tagTypeName := tagInfo.TypeName
+
+			// TODO(dustin): !! Non-standard types, but found in real data. Ignore for right now.
+			if tagTypeName == "SSHORT" || tagTypeName == "FLOAT" || tagTypeName == "DOUBLE" {
+				continue
+			}
+
+			tagTypeId, found := TypeNamesR[tagTypeName]
+			if found == false {
+				log.Panicf("type [%s] for [%s] not valid", tagTypeName, tagName)
+				continue
+			}
+
+			it := &IndexedTag{
+				IfdPath: ifdPath,
+				Id:      tagId,
+				Name:    tagName,
+				Type:    tagTypeId,
+			}
+
+			err = ti.Add(it)
+			log.PanicIf(err)
+
+			count++
+		}
+	}
+
+	tagsLogger.Debugf(nil, "(%d) tags loaded.", count)
+
+	return nil
+}

vendor/github.com/dsoprea/go-exif/tags_data.go

@@ -0,0 +1,951 @@
+package exif
+
+var (
+	// From assets/tags.yaml . Needs to be here so it's embedded in the binary.
+	tagsYaml = `
+# Notes:
+#
+# This file was produced from http://www.exiv2.org/tags.html, using the included
+# tool, though that document appears to have some duplicates when all IDs are
+# supposed to be unique (EXIF information only has IDs, not IFDs; IFDs are
+# determined by our pre-existing knowledge of those tags).
+#
+# The webpage that we've produced this file from appears to indicate that
+# ImageWidth is represented by both 0x0100 and 0x0001 depending on whether the
+# encoding is RGB or YCbCr.
+IFD/Exif:
+- id: 0x829a
+  name: ExposureTime
+  type_name: RATIONAL
+- id: 0x829d
+  name: FNumber
+  type_name: RATIONAL
+- id: 0x8822
+  name: ExposureProgram
+  type_name: SHORT
+- id: 0x8824
+  name: SpectralSensitivity
+  type_name: ASCII
+- id: 0x8827
+  name: ISOSpeedRatings
+  type_name: SHORT
+- id: 0x8828
+  name: OECF
+  type_name: UNDEFINED
+- id: 0x8830
+  name: SensitivityType
+  type_name: SHORT
+- id: 0x8831
+  name: StandardOutputSensitivity
+  type_name: LONG
+- id: 0x8832
+  name: RecommendedExposureIndex
+  type_name: LONG
+- id: 0x8833
+  name: ISOSpeed
+  type_name: LONG
+- id: 0x8834
+  name: ISOSpeedLatitudeyyy
+  type_name: LONG
+- id: 0x8835
+  name: ISOSpeedLatitudezzz
+  type_name: LONG
+- id: 0x9000
+  name: ExifVersion
+  type_name: UNDEFINED
+- id: 0x9003
+  name: DateTimeOriginal
+  type_name: ASCII
+- id: 0x9004
+  name: DateTimeDigitized
+  type_name: ASCII
+- id: 0x9101
+  name: ComponentsConfiguration
+  type_name: UNDEFINED
+- id: 0x9102
+  name: CompressedBitsPerPixel
+  type_name: RATIONAL
+- id: 0x9201
+  name: ShutterSpeedValue
+  type_name: SRATIONAL
+- id: 0x9202
+  name: ApertureValue
+  type_name: RATIONAL
+- id: 0x9203
+  name: BrightnessValue
+  type_name: SRATIONAL
+- id: 0x9204
+  name: ExposureBiasValue
+  type_name: SRATIONAL
+- id: 0x9205
+  name: MaxApertureValue
+  type_name: RATIONAL
+- id: 0x9206
+  name: SubjectDistance
+  type_name: RATIONAL
+- id: 0x9207
+  name: MeteringMode
+  type_name: SHORT
+- id: 0x9208
+  name: LightSource
+  type_name: SHORT
+- id: 0x9209
+  name: Flash
+  type_name: SHORT
+- id: 0x920a
+  name: FocalLength
+  type_name: RATIONAL
+- id: 0x9214
+  name: SubjectArea
+  type_name: SHORT
+- id: 0x927c
+  name: MakerNote
+  type_name: UNDEFINED
+- id: 0x9286
+  name: UserComment
+  type_name: UNDEFINED
+- id: 0x9290
+  name: SubSecTime
+  type_name: ASCII
+- id: 0x9291
+  name: SubSecTimeOriginal
+  type_name: ASCII
+- id: 0x9292
+  name: SubSecTimeDigitized
+  type_name: ASCII
+- id: 0xa000
+  name: FlashpixVersion
+  type_name: UNDEFINED
+- id: 0xa001
+  name: ColorSpace
+  type_name: SHORT
+- id: 0xa002
+  name: PixelXDimension
+  type_name: LONG
+- id: 0xa003
+  name: PixelYDimension
+  type_name: LONG
+- id: 0xa004
+  name: RelatedSoundFile
+  type_name: ASCII
+- id: 0xa005
+  name: InteroperabilityTag
+  type_name: LONG
+- id: 0xa20b
+  name: FlashEnergy
+  type_name: RATIONAL
+- id: 0xa20c
+  name: SpatialFrequencyResponse
+  type_name: UNDEFINED
+- id: 0xa20e
+  name: FocalPlaneXResolution
+  type_name: RATIONAL
+- id: 0xa20f
+  name: FocalPlaneYResolution
+  type_name: RATIONAL
+- id: 0xa210
+  name: FocalPlaneResolutionUnit
+  type_name: SHORT
+- id: 0xa214
+  name: SubjectLocation
+  type_name: SHORT
+- id: 0xa215
+  name: ExposureIndex
+  type_name: RATIONAL
+- id: 0xa217
+  name: SensingMethod
+  type_name: SHORT
+- id: 0xa300
+  name: FileSource
+  type_name: UNDEFINED
+- id: 0xa301
+  name: SceneType
+  type_name: UNDEFINED
+- id: 0xa302
+  name: CFAPattern
+  type_name: UNDEFINED
+- id: 0xa401
+  name: CustomRendered
+  type_name: SHORT
+- id: 0xa402
+  name: ExposureMode
+  type_name: SHORT
+- id: 0xa403
+  name: WhiteBalance
+  type_name: SHORT
+- id: 0xa404
+  name: DigitalZoomRatio
+  type_name: RATIONAL
+- id: 0xa405
+  name: FocalLengthIn35mmFilm
+  type_name: SHORT
+- id: 0xa406
+  name: SceneCaptureType
+  type_name: SHORT
+- id: 0xa407
+  name: GainControl
+  type_name: SHORT
+- id: 0xa408
+  name: Contrast
+  type_name: SHORT
+- id: 0xa409
+  name: Saturation
+  type_name: SHORT
+- id: 0xa40a
+  name: Sharpness
+  type_name: SHORT
+- id: 0xa40b
+  name: DeviceSettingDescription
+  type_name: UNDEFINED
+- id: 0xa40c
+  name: SubjectDistanceRange
+  type_name: SHORT
+- id: 0xa420
+  name: ImageUniqueID
+  type_name: ASCII
+- id: 0xa430
+  name: CameraOwnerName
+  type_name: ASCII
+- id: 0xa431
+  name: BodySerialNumber
+  type_name: ASCII
+- id: 0xa432
+  name: LensSpecification
+  type_name: RATIONAL
+- id: 0xa433
+  name: LensMake
+  type_name: ASCII
+- id: 0xa434
+  name: LensModel
+  type_name: ASCII
+- id: 0xa435
+  name: LensSerialNumber
+  type_name: ASCII
+IFD/GPSInfo:
+- id: 0x0000
+  name: GPSVersionID
+  type_name: BYTE
+- id: 0x0001
+  name: GPSLatitudeRef
+  type_name: ASCII
+- id: 0x0002
+  name: GPSLatitude
+  type_name: RATIONAL
+- id: 0x0003
+  name: GPSLongitudeRef
+  type_name: ASCII
+- id: 0x0004
+  name: GPSLongitude
+  type_name: RATIONAL
+- id: 0x0005
+  name: GPSAltitudeRef
+  type_name: BYTE
+- id: 0x0006
+  name: GPSAltitude
+  type_name: RATIONAL
+- id: 0x0007
+  name: GPSTimeStamp
+  type_name: RATIONAL
+- id: 0x0008
+  name: GPSSatellites
+  type_name: ASCII
+- id: 0x0009
+  name: GPSStatus
+  type_name: ASCII
+- id: 0x000a
+  name: GPSMeasureMode
+  type_name: ASCII
+- id: 0x000b
+  name: GPSDOP
+  type_name: RATIONAL
+- id: 0x000c
+  name: GPSSpeedRef
+  type_name: ASCII
+- id: 0x000d
+  name: GPSSpeed
+  type_name: RATIONAL
+- id: 0x000e
+  name: GPSTrackRef
+  type_name: ASCII
+- id: 0x000f
+  name: GPSTrack
+  type_name: RATIONAL
+- id: 0x0010
+  name: GPSImgDirectionRef
+  type_name: ASCII
+- id: 0x0011
+  name: GPSImgDirection
+  type_name: RATIONAL
+- id: 0x0012
+  name: GPSMapDatum
+  type_name: ASCII
+- id: 0x0013
+  name: GPSDestLatitudeRef
+  type_name: ASCII
+- id: 0x0014
+  name: GPSDestLatitude
+  type_name: RATIONAL
+- id: 0x0015
+  name: GPSDestLongitudeRef
+  type_name: ASCII
+- id: 0x0016
+  name: GPSDestLongitude
+  type_name: RATIONAL
+- id: 0x0017
+  name: GPSDestBearingRef
+  type_name: ASCII
+- id: 0x0018
+  name: GPSDestBearing
+  type_name: RATIONAL
+- id: 0x0019
+  name: GPSDestDistanceRef
+  type_name: ASCII
+- id: 0x001a
+  name: GPSDestDistance
+  type_name: RATIONAL
+- id: 0x001b
+  name: GPSProcessingMethod
+  type_name: UNDEFINED
+- id: 0x001c
+  name: GPSAreaInformation
+  type_name: UNDEFINED
+- id: 0x001d
+  name: GPSDateStamp
+  type_name: ASCII
+- id: 0x001e
+  name: GPSDifferential
+  type_name: SHORT
+IFD:
+- id: 0x000b
+  name: ProcessingSoftware
+  type_name: ASCII
+- id: 0x00fe
+  name: NewSubfileType
+  type_name: LONG
+- id: 0x00ff
+  name: SubfileType
+  type_name: SHORT
+- id: 0x0100
+  name: ImageWidth
+  type_name: LONG
+- id: 0x0101
+  name: ImageLength
+  type_name: LONG
+- id: 0x0102
+  name: BitsPerSample
+  type_name: SHORT
+- id: 0x0103
+  name: Compression
+  type_name: SHORT
+- id: 0x0106
+  name: PhotometricInterpretation
+  type_name: SHORT
+- id: 0x0107
+  name: Thresholding
+  type_name: SHORT
+- id: 0x0108
+  name: CellWidth
+  type_name: SHORT
+- id: 0x0109
+  name: CellLength
+  type_name: SHORT
+- id: 0x010a
+  name: FillOrder
+  type_name: SHORT
+- id: 0x010d
+  name: DocumentName
+  type_name: ASCII
+- id: 0x010e
+  name: ImageDescription
+  type_name: ASCII
+- id: 0x010f
+  name: Make
+  type_name: ASCII
+- id: 0x0110
+  name: Model
+  type_name: ASCII
+- id: 0x0111
+  name: StripOffsets
+  type_name: LONG
+- id: 0x0112
+  name: Orientation
+  type_name: SHORT
+- id: 0x0115
+  name: SamplesPerPixel
+  type_name: SHORT
+- id: 0x0116
+  name: RowsPerStrip
+  type_name: LONG
+- id: 0x0117
+  name: StripByteCounts
+  type_name: LONG
+- id: 0x011a
+  name: XResolution
+  type_name: RATIONAL
+- id: 0x011b
+  name: YResolution
+  type_name: RATIONAL
+- id: 0x011c
+  name: PlanarConfiguration
+  type_name: SHORT
+- id: 0x0122
+  name: GrayResponseUnit
+  type_name: SHORT
+- id: 0x0123
+  name: GrayResponseCurve
+  type_name: SHORT
+- id: 0x0124
+  name: T4Options
+  type_name: LONG
+- id: 0x0125
+  name: T6Options
+  type_name: LONG
+- id: 0x0128
+  name: ResolutionUnit
+  type_name: SHORT
+- id: 0x0129
+  name: PageNumber
+  type_name: SHORT
+- id: 0x012d
+  name: TransferFunction
+  type_name: SHORT
+- id: 0x0131
+  name: Software
+  type_name: ASCII
+- id: 0x0132
+  name: DateTime
+  type_name: ASCII
+- id: 0x013b
+  name: Artist
+  type_name: ASCII
+- id: 0x013c
+  name: HostComputer
+  type_name: ASCII
+- id: 0x013d
+  name: Predictor
+  type_name: SHORT
+- id: 0x013e
+  name: WhitePoint
+  type_name: RATIONAL
+- id: 0x013f
+  name: PrimaryChromaticities
+  type_name: RATIONAL
+- id: 0x0140
+  name: ColorMap
+  type_name: SHORT
+- id: 0x0141
+  name: HalftoneHints
+  type_name: SHORT
+- id: 0x0142
+  name: TileWidth
+  type_name: SHORT
+- id: 0x0143
+  name: TileLength
+  type_name: SHORT
+- id: 0x0144
+  name: TileOffsets
+  type_name: SHORT
+- id: 0x0145
+  name: TileByteCounts
+  type_name: SHORT
+- id: 0x014a
+  name: SubIFDs
+  type_name: LONG
+- id: 0x014c
+  name: InkSet
+  type_name: SHORT
+- id: 0x014d
+  name: InkNames
+  type_name: ASCII
+- id: 0x014e
+  name: NumberOfInks
+  type_name: SHORT
+- id: 0x0150
+  name: DotRange
+  type_name: BYTE
+- id: 0x0151
+  name: TargetPrinter
+  type_name: ASCII
+- id: 0x0152
+  name: ExtraSamples
+  type_name: SHORT
+- id: 0x0153
+  name: SampleFormat
+  type_name: SHORT
+- id: 0x0154
+  name: SMinSampleValue
+  type_name: SHORT
+- id: 0x0155
+  name: SMaxSampleValue
+  type_name: SHORT
+- id: 0x0156
+  name: TransferRange
+  type_name: SHORT
+- id: 0x0157
+  name: ClipPath
+  type_name: BYTE
+- id: 0x0158
+  name: XClipPathUnits
+  type_name: SSHORT
+- id: 0x0159
+  name: YClipPathUnits
+  type_name: SSHORT
+- id: 0x015a
+  name: Indexed
+  type_name: SHORT
+- id: 0x015b
+  name: JPEGTables
+  type_name: UNDEFINED
+- id: 0x015f
+  name: OPIProxy
+  type_name: SHORT
+- id: 0x0200
+  name: JPEGProc
+  type_name: LONG
+- id: 0x0201
+  name: JPEGInterchangeFormat
+  type_name: LONG
+- id: 0x0202
+  name: JPEGInterchangeFormatLength
+  type_name: LONG
+- id: 0x0203
+  name: JPEGRestartInterval
+  type_name: SHORT
+- id: 0x0205
+  name: JPEGLosslessPredictors
+  type_name: SHORT
+- id: 0x0206
+  name: JPEGPointTransforms
+  type_name: SHORT
+- id: 0x0207
+  name: JPEGQTables
+  type_name: LONG
+- id: 0x0208
+  name: JPEGDCTables
+  type_name: LONG
+- id: 0x0209
+  name: JPEGACTables
+  type_name: LONG
+- id: 0x0211
+  name: YCbCrCoefficients
+  type_name: RATIONAL
+- id: 0x0212
+  name: YCbCrSubSampling
+  type_name: SHORT
+- id: 0x0213
+  name: YCbCrPositioning
+  type_name: SHORT
+- id: 0x0214
+  name: ReferenceBlackWhite
+  type_name: RATIONAL
+- id: 0x02bc
+  name: XMLPacket
+  type_name: BYTE
+- id: 0x4746
+  name: Rating
+  type_name: SHORT
+- id: 0x4749
+  name: RatingPercent
+  type_name: SHORT
+- id: 0x800d
+  name: ImageID
+  type_name: ASCII
+- id: 0x828d
+  name: CFARepeatPatternDim
+  type_name: SHORT
+- id: 0x828e
+  name: CFAPattern
+  type_name: BYTE
+- id: 0x828f
+  name: BatteryLevel
+  type_name: RATIONAL
+- id: 0x8298
+  name: Copyright
+  type_name: ASCII
+- id: 0x829a
+  name: ExposureTime
+  type_name: RATIONAL
+- id: 0x829d
+  name: FNumber
+  type_name: RATIONAL
+- id: 0x83bb
+  name: IPTCNAA
+  type_name: LONG
+- id: 0x8649
+  name: ImageResources
+  type_name: BYTE
+- id: 0x8769
+  name: ExifTag
+  type_name: LONG
+- id: 0x8773
+  name: InterColorProfile
+  type_name: UNDEFINED
+- id: 0x8822
+  name: ExposureProgram
+  type_name: SHORT
+- id: 0x8824
+  name: SpectralSensitivity
+  type_name: ASCII
+- id: 0x8825
+  name: GPSTag
+  type_name: LONG
+- id: 0x8827
+  name: ISOSpeedRatings
+  type_name: SHORT
+- id: 0x8828
+  name: OECF
+  type_name: UNDEFINED
+- id: 0x8829
+  name: Interlace
+  type_name: SHORT
+- id: 0x882a
+  name: TimeZoneOffset
+  type_name: SSHORT
+- id: 0x882b
+  name: SelfTimerMode
+  type_name: SHORT
+- id: 0x9003
+  name: DateTimeOriginal
+  type_name: ASCII
+- id: 0x9102
+  name: CompressedBitsPerPixel
+  type_name: RATIONAL
+- id: 0x9201
+  name: ShutterSpeedValue
+  type_name: SRATIONAL
+- id: 0x9202
+  name: ApertureValue
+  type_name: RATIONAL
+- id: 0x9203
+  name: BrightnessValue
+  type_name: SRATIONAL
+- id: 0x9204
+  name: ExposureBiasValue
+  type_name: SRATIONAL
+- id: 0x9205
+  name: MaxApertureValue
+  type_name: RATIONAL
+- id: 0x9206
+  name: SubjectDistance
+  type_name: SRATIONAL
+- id: 0x9207
+  name: MeteringMode
+  type_name: SHORT
+- id: 0x9208
+  name: LightSource
+  type_name: SHORT
+- id: 0x9209
+  name: Flash
+  type_name: SHORT
+- id: 0x920a
+  name: FocalLength
+  type_name: RATIONAL
+- id: 0x920b
+  name: FlashEnergy
+  type_name: RATIONAL
+- id: 0x920c
+  name: SpatialFrequencyResponse
+  type_name: UNDEFINED
+- id: 0x920d
+  name: Noise
+  type_name: UNDEFINED
+- id: 0x920e
+  name: FocalPlaneXResolution
+  type_name: RATIONAL
+- id: 0x920f
+  name: FocalPlaneYResolution
+  type_name: RATIONAL
+- id: 0x9210
+  name: FocalPlaneResolutionUnit
+  type_name: SHORT
+- id: 0x9211
+  name: ImageNumber
+  type_name: LONG
+- id: 0x9212
+  name: SecurityClassification
+  type_name: ASCII
+- id: 0x9213
+  name: ImageHistory
+  type_name: ASCII
+- id: 0x9214
+  name: SubjectLocation
+  type_name: SHORT
+- id: 0x9215
+  name: ExposureIndex
+  type_name: RATIONAL
+- id: 0x9216
+  name: TIFFEPStandardID
+  type_name: BYTE
+- id: 0x9217
+  name: SensingMethod
+  type_name: SHORT
+- id: 0x9c9b
+  name: XPTitle
+  type_name: BYTE
+- id: 0x9c9c
+  name: XPComment
+  type_name: BYTE
+- id: 0x9c9d
+  name: XPAuthor
+  type_name: BYTE
+- id: 0x9c9e
+  name: XPKeywords
+  type_name: BYTE
+- id: 0x9c9f
+  name: XPSubject
+  type_name: BYTE
+- id: 0xc4a5
+  name: PrintImageMatching
+  type_name: UNDEFINED
+- id: 0xc612
+  name: DNGVersion
+  type_name: BYTE
+- id: 0xc613
+  name: DNGBackwardVersion
+  type_name: BYTE
+- id: 0xc614
+  name: UniqueCameraModel
+  type_name: ASCII
+- id: 0xc615
+  name: LocalizedCameraModel
+  type_name: BYTE
+- id: 0xc616
+  name: CFAPlaneColor
+  type_name: BYTE
+- id: 0xc617
+  name: CFALayout
+  type_name: SHORT
+- id: 0xc618
+  name: LinearizationTable
+  type_name: SHORT
+- id: 0xc619
+  name: BlackLevelRepeatDim
+  type_name: SHORT
+- id: 0xc61a
+  name: BlackLevel
+  type_name: RATIONAL
+- id: 0xc61b
+  name: BlackLevelDeltaH
+  type_name: SRATIONAL
+- id: 0xc61c
+  name: BlackLevelDeltaV
+  type_name: SRATIONAL
+- id: 0xc61d
+  name: WhiteLevel
+  type_name: SHORT
+- id: 0xc61e
+  name: DefaultScale
+  type_name: RATIONAL
+- id: 0xc61f
+  name: DefaultCropOrigin
+  type_name: SHORT
+- id: 0xc620
+  name: DefaultCropSize
+  type_name: SHORT
+- id: 0xc621
+  name: ColorMatrix1
+  type_name: SRATIONAL
+- id: 0xc622
+  name: ColorMatrix2
+  type_name: SRATIONAL
+- id: 0xc623
+  name: CameraCalibration1
+  type_name: SRATIONAL
+- id: 0xc624
+  name: CameraCalibration2
+  type_name: SRATIONAL
+- id: 0xc625
+  name: ReductionMatrix1
+  type_name: SRATIONAL
+- id: 0xc626
+  name: ReductionMatrix2
+  type_name: SRATIONAL
+- id: 0xc627
+  name: AnalogBalance
+  type_name: RATIONAL
+- id: 0xc628
+  name: AsShotNeutral
+  type_name: SHORT
+- id: 0xc629
+  name: AsShotWhiteXY
+  type_name: RATIONAL
+- id: 0xc62a
+  name: BaselineExposure
+  type_name: SRATIONAL
+- id: 0xc62b
+  name: BaselineNoise
+  type_name: RATIONAL
+- id: 0xc62c
+  name: BaselineSharpness
+  type_name: RATIONAL
+- id: 0xc62d
+  name: BayerGreenSplit
+  type_name: LONG
+- id: 0xc62e
+  name: LinearResponseLimit
+  type_name: RATIONAL
+- id: 0xc62f
+  name: CameraSerialNumber
+  type_name: ASCII
+- id: 0xc630
+  name: LensInfo
+  type_name: RATIONAL
+- id: 0xc631
+  name: ChromaBlurRadius
+  type_name: RATIONAL
+- id: 0xc632
+  name: AntiAliasStrength
+  type_name: RATIONAL
+- id: 0xc633
+  name: ShadowScale
+  type_name: SRATIONAL
+- id: 0xc634
+  name: DNGPrivateData
+  type_name: BYTE
+- id: 0xc635
+  name: MakerNoteSafety
+  type_name: SHORT
+- id: 0xc65a
+  name: CalibrationIlluminant1
+  type_name: SHORT
+- id: 0xc65b
+  name: CalibrationIlluminant2
+  type_name: SHORT
+- id: 0xc65c
+  name: BestQualityScale
+  type_name: RATIONAL
+- id: 0xc65d
+  name: RawDataUniqueID
+  type_name: BYTE
+- id: 0xc68b
+  name: OriginalRawFileName
+  type_name: BYTE
+- id: 0xc68c
+  name: OriginalRawFileData
+  type_name: UNDEFINED
+- id: 0xc68d
+  name: ActiveArea
+  type_name: SHORT
+- id: 0xc68e
+  name: MaskedAreas
+  type_name: SHORT
+- id: 0xc68f
+  name: AsShotICCProfile
+  type_name: UNDEFINED
+- id: 0xc690
+  name: AsShotPreProfileMatrix
+  type_name: SRATIONAL
+- id: 0xc691
+  name: CurrentICCProfile
+  type_name: UNDEFINED
+- id: 0xc692
+  name: CurrentPreProfileMatrix
+  type_name: SRATIONAL
+- id: 0xc6bf
+  name: ColorimetricReference
+  type_name: SHORT
+- id: 0xc6f3
+  name: CameraCalibrationSignature
+  type_name: BYTE
+- id: 0xc6f4
+  name: ProfileCalibrationSignature
+  type_name: BYTE
+- id: 0xc6f6
+  name: AsShotProfileName
+  type_name: BYTE
+- id: 0xc6f7
+  name: NoiseReductionApplied
+  type_name: RATIONAL
+- id: 0xc6f8
+  name: ProfileName
+  type_name: BYTE
+- id: 0xc6f9
+  name: ProfileHueSatMapDims
+  type_name: LONG
+- id: 0xc6fa
+  name: ProfileHueSatMapData1
+  type_name: FLOAT
+- id: 0xc6fb
+  name: ProfileHueSatMapData2
+  type_name: FLOAT
+- id: 0xc6fc
+  name: ProfileToneCurve
+  type_name: FLOAT
+- id: 0xc6fd
+  name: ProfileEmbedPolicy
+  type_name: LONG
+- id: 0xc6fe
+  name: ProfileCopyright
+  type_name: BYTE
+- id: 0xc714
+  name: ForwardMatrix1
+  type_name: SRATIONAL
+- id: 0xc715
+  name: ForwardMatrix2
+  type_name: SRATIONAL
+- id: 0xc716
+  name: PreviewApplicationName
+  type_name: BYTE
+- id: 0xc717
+  name: PreviewApplicationVersion
+  type_name: BYTE
+- id: 0xc718
+  name: PreviewSettingsName
+  type_name: BYTE
+- id: 0xc719
+  name: PreviewSettingsDigest
+  type_name: BYTE
+- id: 0xc71a
+  name: PreviewColorSpace
+  type_name: LONG
+- id: 0xc71b
+  name: PreviewDateTime
+  type_name: ASCII
+- id: 0xc71c
+  name: RawImageDigest
+  type_name: UNDEFINED
+- id: 0xc71d
+  name: OriginalRawFileDigest
+  type_name: UNDEFINED
+- id: 0xc71e
+  name: SubTileBlockSize
+  type_name: LONG
+- id: 0xc71f
+  name: RowInterleaveFactor
+  type_name: LONG
+- id: 0xc725
+  name: ProfileLookTableDims
+  type_name: LONG
+- id: 0xc726
+  name: ProfileLookTableData
+  type_name: FLOAT
+- id: 0xc740
+  name: OpcodeList1
+  type_name: UNDEFINED
+- id: 0xc741
+  name: OpcodeList2
+  type_name: UNDEFINED
+- id: 0xc74e
+  name: OpcodeList3
+  type_name: UNDEFINED
+- id: 0xc761
+  name: NoiseProfile
+  type_name: DOUBLE
+IFD/Exif/Iop:
+- id: 0x0001
+  name: InteroperabilityIndex
+  type_name: ASCII
+- id: 0x0002
+  name: InteroperabilityVersion
+  type_name: UNDEFINED
+- id: 0x1000
+  name: RelatedImageFileFormat
+  type_name: ASCII
+- id: 0x1001
+  name: RelatedImageWidth
+  type_name: LONG
+- id: 0x1002
+  name: RelatedImageLength
+  type_name: LONG
+`
+)

vendor/github.com/dsoprea/go-exif/tags_undefined.go

@@ -0,0 +1,417 @@
+package exif
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"crypto/sha1"
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+const (
+	UnparseableUnknownTagValuePlaceholder = "!UNKNOWN"
+)
+
+// TODO(dustin): Rename "unknown" in symbol names to "undefined" in the next release.
+//
+// See https://github.com/dsoprea/go-exif/issues/27 .
+
+const (
+	TagUnknownType_9298_UserComment_Encoding_ASCII     = iota
+	TagUnknownType_9298_UserComment_Encoding_JIS       = iota
+	TagUnknownType_9298_UserComment_Encoding_UNICODE   = iota
+	TagUnknownType_9298_UserComment_Encoding_UNDEFINED = iota
+)
+
+const (
+	TagUnknownType_9101_ComponentsConfiguration_Channel_Y  = 0x1
+	TagUnknownType_9101_ComponentsConfiguration_Channel_Cb = 0x2
+	TagUnknownType_9101_ComponentsConfiguration_Channel_Cr = 0x3
+	TagUnknownType_9101_ComponentsConfiguration_Channel_R  = 0x4
+	TagUnknownType_9101_ComponentsConfiguration_Channel_G  = 0x5
+	TagUnknownType_9101_ComponentsConfiguration_Channel_B  = 0x6
+)
+
+const (
+	TagUnknownType_9101_ComponentsConfiguration_OTHER = iota
+	TagUnknownType_9101_ComponentsConfiguration_RGB   = iota
+	TagUnknownType_9101_ComponentsConfiguration_YCBCR = iota
+)
+
+var (
+	TagUnknownType_9298_UserComment_Encoding_Names = map[int]string{
+		TagUnknownType_9298_UserComment_Encoding_ASCII:     "ASCII",
+		TagUnknownType_9298_UserComment_Encoding_JIS:       "JIS",
+		TagUnknownType_9298_UserComment_Encoding_UNICODE:   "UNICODE",
+		TagUnknownType_9298_UserComment_Encoding_UNDEFINED: "UNDEFINED",
+	}
+
+	TagUnknownType_9298_UserComment_Encodings = map[int][]byte{
+		TagUnknownType_9298_UserComment_Encoding_ASCII:     {'A', 'S', 'C', 'I', 'I', 0, 0, 0},
+		TagUnknownType_9298_UserComment_Encoding_JIS:       {'J', 'I', 'S', 0, 0, 0, 0, 0},
+		TagUnknownType_9298_UserComment_Encoding_UNICODE:   {'U', 'n', 'i', 'c', 'o', 'd', 'e', 0},
+		TagUnknownType_9298_UserComment_Encoding_UNDEFINED: {0, 0, 0, 0, 0, 0, 0, 0},
+	}
+
+	TagUnknownType_9101_ComponentsConfiguration_Names = map[int]string{
+		TagUnknownType_9101_ComponentsConfiguration_OTHER: "OTHER",
+		TagUnknownType_9101_ComponentsConfiguration_RGB:   "RGB",
+		TagUnknownType_9101_ComponentsConfiguration_YCBCR: "YCBCR",
+	}
+
+	TagUnknownType_9101_ComponentsConfiguration_Configurations = map[int][]byte{
+		TagUnknownType_9101_ComponentsConfiguration_RGB: {
+			TagUnknownType_9101_ComponentsConfiguration_Channel_R,
+			TagUnknownType_9101_ComponentsConfiguration_Channel_G,
+			TagUnknownType_9101_ComponentsConfiguration_Channel_B,
+			0,
+		},
+
+		TagUnknownType_9101_ComponentsConfiguration_YCBCR: {
+			TagUnknownType_9101_ComponentsConfiguration_Channel_Y,
+			TagUnknownType_9101_ComponentsConfiguration_Channel_Cb,
+			TagUnknownType_9101_ComponentsConfiguration_Channel_Cr,
+			0,
+		},
+	}
+)
+
+// TODO(dustin): Rename `UnknownTagValue` to `UndefinedTagValue`.
+
+type UnknownTagValue interface {
+	ValueBytes() ([]byte, error)
+}
+
+// TODO(dustin): Rename `TagUnknownType_GeneralString` to `TagUnknownType_GeneralString`.
+
+type TagUnknownType_GeneralString string
+
+func (gs TagUnknownType_GeneralString) ValueBytes() (value []byte, err error) {
+	return []byte(gs), nil
+}
+
+// TODO(dustin): Rename `TagUnknownType_9298_UserComment` to `TagUndefinedType_9298_UserComment`.
+
+type TagUnknownType_9298_UserComment struct {
+	EncodingType  int
+	EncodingBytes []byte
+}
+
+func (uc TagUnknownType_9298_UserComment) String() string {
+	var valuePhrase string
+
+	if len(uc.EncodingBytes) <= 8 {
+		valuePhrase = fmt.Sprintf("%v", uc.EncodingBytes)
+	} else {
+		valuePhrase = fmt.Sprintf("%v...", uc.EncodingBytes[:8])
+	}
+
+	return fmt.Sprintf("UserComment<SIZE=(%d) ENCODING=[%s] V=%v LEN=(%d)>", len(uc.EncodingBytes), TagUnknownType_9298_UserComment_Encoding_Names[uc.EncodingType], valuePhrase, len(uc.EncodingBytes))
+}
+
+func (uc TagUnknownType_9298_UserComment) ValueBytes() (value []byte, err error) {
+	encodingTypeBytes, found := TagUnknownType_9298_UserComment_Encodings[uc.EncodingType]
+	if found == false {
+		log.Panicf("encoding-type not valid for unknown-type tag 9298 (UserComment): (%d)", uc.EncodingType)
+	}
+
+	value = make([]byte, len(uc.EncodingBytes)+8)
+
+	copy(value[:8], encodingTypeBytes)
+	copy(value[8:], uc.EncodingBytes)
+
+	return value, nil
+}
+
+// TODO(dustin): Rename `TagUnknownType_927C_MakerNote` to `TagUndefinedType_927C_MakerNote`.
+
+type TagUnknownType_927C_MakerNote struct {
+	MakerNoteType  []byte
+	MakerNoteBytes []byte
+}
+
+func (mn TagUnknownType_927C_MakerNote) String() string {
+	parts := make([]string, 20)
+	for i, c := range mn.MakerNoteType {
+		parts[i] = fmt.Sprintf("%02x", c)
+	}
+
+	h := sha1.New()
+
+	_, err := h.Write(mn.MakerNoteBytes)
+	log.PanicIf(err)
+
+	digest := h.Sum(nil)
+
+	return fmt.Sprintf("MakerNote<TYPE-ID=[%s] LEN=(%d) SHA1=[%020x]>", strings.Join(parts, " "), len(mn.MakerNoteBytes), digest)
+}
+
+func (uc TagUnknownType_927C_MakerNote) ValueBytes() (value []byte, err error) {
+	return uc.MakerNoteBytes, nil
+}
+
+// TODO(dustin): Rename `TagUnknownType_9101_ComponentsConfiguration` to `TagUndefinedType_9101_ComponentsConfiguration`.
+
+type TagUnknownType_9101_ComponentsConfiguration struct {
+	ConfigurationId    int
+	ConfigurationBytes []byte
+}
+
+func (cc TagUnknownType_9101_ComponentsConfiguration) String() string {
+	return fmt.Sprintf("ComponentsConfiguration<ID=[%s] BYTES=%v>", TagUnknownType_9101_ComponentsConfiguration_Names[cc.ConfigurationId], cc.ConfigurationBytes)
+}
+
+func (uc TagUnknownType_9101_ComponentsConfiguration) ValueBytes() (value []byte, err error) {
+	return uc.ConfigurationBytes, nil
+}
+
+// TODO(dustin): Rename `EncodeUnknown_9286` to `EncodeUndefined_9286`.
+
+func EncodeUnknown_9286(uc TagUnknownType_9298_UserComment) (encoded []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	b := new(bytes.Buffer)
+
+	encodingTypeBytes := TagUnknownType_9298_UserComment_Encodings[uc.EncodingType]
+
+	_, err = b.Write(encodingTypeBytes)
+	log.PanicIf(err)
+
+	_, err = b.Write(uc.EncodingBytes)
+	log.PanicIf(err)
+
+	return b.Bytes(), nil
+}
+
+type EncodeableUndefinedValue struct {
+	IfdPath    string
+	TagId      uint16
+	Parameters interface{}
+}
+
+func EncodeUndefined(ifdPath string, tagId uint16, value interface{}) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! Finish implementing these.
+	if ifdPath == IfdPathStandardExif {
+		if tagId == 0x9286 {
+			encoded, err := EncodeUnknown_9286(value.(TagUnknownType_9298_UserComment))
+			log.PanicIf(err)
+
+			ed.Type = TypeUndefined
+			ed.Encoded = encoded
+			ed.UnitCount = uint32(len(encoded))
+
+			return ed, nil
+		}
+	}
+
+	log.Panicf("undefined value not encodable: %s (0x%02x)", ifdPath, tagId)
+
+	// Never called.
+	return EncodedData{}, nil
+}
+
+// TODO(dustin): Rename `TagUnknownType_UnknownValue` to `TagUndefinedType_UnknownValue`.
+
+type TagUnknownType_UnknownValue []byte
+
+func (tutuv TagUnknownType_UnknownValue) String() string {
+	parts := make([]string, len(tutuv))
+	for i, c := range tutuv {
+		parts[i] = fmt.Sprintf("%02x", c)
+	}
+
+	h := sha1.New()
+
+	_, err := h.Write(tutuv)
+	log.PanicIf(err)
+
+	digest := h.Sum(nil)
+
+	return fmt.Sprintf("Unknown<DATA=[%s] LEN=(%d) SHA1=[%020x]>", strings.Join(parts, " "), len(tutuv), digest)
+}
+
+// UndefinedValue knows how to resolve the value for most unknown-type tags.
+func UndefinedValue(ifdPath string, tagId uint16, valueContext interface{}, byteOrder binary.ByteOrder) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Stop exporting this. Use `(*ValueContext).Undefined()`.
+
+	var valueContextPtr *ValueContext
+
+	if vc, ok := valueContext.(*ValueContext); ok == true {
+		// Legacy usage.
+
+		valueContextPtr = vc
+	} else {
+		// Standard usage.
+
+		valueContextValue := valueContext.(ValueContext)
+		valueContextPtr = &valueContextValue
+	}
+
+	typeLogger.Debugf(nil, "UndefinedValue: IFD-PATH=[%s] TAG-ID=(0x%02x)", ifdPath, tagId)
+
+	if ifdPath == IfdPathStandardExif {
+		if tagId == 0x9000 {
+			// ExifVersion
+
+			valueContextPtr.SetUnknownValueType(TypeAsciiNoNul)
+
+			valueString, err := valueContextPtr.ReadAsciiNoNul()
+			log.PanicIf(err)
+
+			return TagUnknownType_GeneralString(valueString), nil
+		} else if tagId == 0xa000 {
+			// FlashpixVersion
+
+			valueContextPtr.SetUnknownValueType(TypeAsciiNoNul)
+
+			valueString, err := valueContextPtr.ReadAsciiNoNul()
+			log.PanicIf(err)
+
+			return TagUnknownType_GeneralString(valueString), nil
+		} else if tagId == 0x9286 {
+			// UserComment
+
+			valueContextPtr.SetUnknownValueType(TypeByte)
+
+			valueBytes, err := valueContextPtr.ReadBytes()
+			log.PanicIf(err)
+
+			unknownUc := TagUnknownType_9298_UserComment{
+				EncodingType:  TagUnknownType_9298_UserComment_Encoding_UNDEFINED,
+				EncodingBytes: []byte{},
+			}
+
+			encoding := valueBytes[:8]
+			for encodingIndex, encodingBytes := range TagUnknownType_9298_UserComment_Encodings {
+				if bytes.Compare(encoding, encodingBytes) == 0 {
+					uc := TagUnknownType_9298_UserComment{
+						EncodingType:  encodingIndex,
+						EncodingBytes: valueBytes[8:],
+					}
+
+					return uc, nil
+				}
+			}
+
+			typeLogger.Warningf(nil, "User-comment encoding not valid. Returning 'unknown' type (the default).")
+			return unknownUc, nil
+		} else if tagId == 0x927c {
+			// MakerNote
+			// TODO(dustin): !! This is the Wild Wild West. This very well might be a child IFD, but any and all OEM's define their own formats. If we're going to be writing changes and this is complete EXIF (which may not have the first eight bytes), it might be fine. However, if these are just IFDs they'll be relative to the main EXIF, this will invalidate the MakerNote data for IFDs and any other implementations that use offsets unless we can interpret them all. It be best to return to this later and just exclude this from being written for now, though means a loss of a wealth of image metadata.
+			//                  -> We can also just blindly try to interpret as an IFD and just validate that it's looks good (maybe it will even have a 'next ifd' pointer that we can validate is 0x0).
+
+			valueContextPtr.SetUnknownValueType(TypeByte)
+
+			valueBytes, err := valueContextPtr.ReadBytes()
+			log.PanicIf(err)
+
+			// TODO(dustin): Doesn't work, but here as an example.
+			//             ie := NewIfdEnumerate(valueBytes, byteOrder)
+
+			// // TODO(dustin): !! Validate types (might have proprietary types, but it might be worth splitting the list between valid and not valid; maybe fail if a certain proportion are invalid, or maybe aren't less then a certain small integer)?
+			//             ii, err := ie.Collect(0x0)
+
+			//             for _, entry := range ii.RootIfd.Entries {
+			//                 fmt.Printf("ENTRY: 0x%02x %d\n", entry.TagId, entry.TagType)
+			//             }
+
+			mn := TagUnknownType_927C_MakerNote{
+				MakerNoteType: valueBytes[:20],
+
+				// MakerNoteBytes has the whole length of bytes. There's always
+				// the chance that the first 20 bytes includes actual data.
+				MakerNoteBytes: valueBytes,
+			}
+
+			return mn, nil
+		} else if tagId == 0x9101 {
+			// ComponentsConfiguration
+
+			valueContextPtr.SetUnknownValueType(TypeByte)
+
+			valueBytes, err := valueContextPtr.ReadBytes()
+			log.PanicIf(err)
+
+			for configurationId, configurationBytes := range TagUnknownType_9101_ComponentsConfiguration_Configurations {
+				if bytes.Compare(valueBytes, configurationBytes) == 0 {
+					cc := TagUnknownType_9101_ComponentsConfiguration{
+						ConfigurationId:    configurationId,
+						ConfigurationBytes: valueBytes,
+					}
+
+					return cc, nil
+				}
+			}
+
+			cc := TagUnknownType_9101_ComponentsConfiguration{
+				ConfigurationId:    TagUnknownType_9101_ComponentsConfiguration_OTHER,
+				ConfigurationBytes: valueBytes,
+			}
+
+			return cc, nil
+		}
+	} else if ifdPath == IfdPathStandardGps {
+		if tagId == 0x001c {
+			// GPSAreaInformation
+
+			valueContextPtr.SetUnknownValueType(TypeAsciiNoNul)
+
+			valueString, err := valueContextPtr.ReadAsciiNoNul()
+			log.PanicIf(err)
+
+			return TagUnknownType_GeneralString(valueString), nil
+		} else if tagId == 0x001b {
+			// GPSProcessingMethod
+
+			valueContextPtr.SetUnknownValueType(TypeAsciiNoNul)
+
+			valueString, err := valueContextPtr.ReadAsciiNoNul()
+			log.PanicIf(err)
+
+			return TagUnknownType_GeneralString(valueString), nil
+		}
+	} else if ifdPath == IfdPathStandardExifIop {
+		if tagId == 0x0002 {
+			// InteropVersion
+
+			valueContextPtr.SetUnknownValueType(TypeAsciiNoNul)
+
+			valueString, err := valueContextPtr.ReadAsciiNoNul()
+			log.PanicIf(err)
+
+			return TagUnknownType_GeneralString(valueString), nil
+		}
+	}
+
+	// TODO(dustin): !! Still need to do:
+	//
+	// complex: 0xa302, 0xa20c, 0x8828
+	// long: 0xa301, 0xa300
+	//
+	// 0xa40b is device-specific and unhandled.
+	//
+	// See https://github.com/dsoprea/go-exif/issues/26.
+
+	// We have no choice but to return the error. We have no way of knowing how
+	// much data there is without already knowing what data-type this tag is.
+	return nil, ErrUnhandledUnknownTypedTag
+}

vendor/github.com/dsoprea/go-exif/type.go

@@ -0,0 +1,310 @@
+package exif
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+type TagTypePrimitive uint16
+
+func (typeType TagTypePrimitive) String() string {
+	return TypeNames[typeType]
+}
+
+func (tagType TagTypePrimitive) Size() int {
+	if tagType == TypeByte {
+		return 1
+	} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
+		return 1
+	} else if tagType == TypeShort {
+		return 2
+	} else if tagType == TypeLong {
+		return 4
+	} else if tagType == TypeRational {
+		return 8
+	} else if tagType == TypeSignedLong {
+		return 4
+	} else if tagType == TypeSignedRational {
+		return 8
+	} else {
+		log.Panicf("can not determine tag-value size for type (%d): [%s]", tagType, TypeNames[tagType])
+
+		// Never called.
+		return 0
+	}
+}
+
+const (
+	TypeByte           TagTypePrimitive = 1
+	TypeAscii          TagTypePrimitive = 2
+	TypeShort          TagTypePrimitive = 3
+	TypeLong           TagTypePrimitive = 4
+	TypeRational       TagTypePrimitive = 5
+	TypeUndefined      TagTypePrimitive = 7
+	TypeSignedLong     TagTypePrimitive = 9
+	TypeSignedRational TagTypePrimitive = 10
+
+	// TypeAsciiNoNul is just a pseudo-type, for our own purposes.
+	TypeAsciiNoNul TagTypePrimitive = 0xf0
+)
+
+var (
+	typeLogger = log.NewLogger("exif.type")
+)
+
+var (
+	// TODO(dustin): Rename TypeNames() to typeNames() and add getter.
+	TypeNames = map[TagTypePrimitive]string{
+		TypeByte:           "BYTE",
+		TypeAscii:          "ASCII",
+		TypeShort:          "SHORT",
+		TypeLong:           "LONG",
+		TypeRational:       "RATIONAL",
+		TypeUndefined:      "UNDEFINED",
+		TypeSignedLong:     "SLONG",
+		TypeSignedRational: "SRATIONAL",
+
+		TypeAsciiNoNul: "_ASCII_NO_NUL",
+	}
+
+	TypeNamesR = map[string]TagTypePrimitive{}
+)
+
+var (
+	// ErrNotEnoughData is used when there isn't enough data to accomodate what
+	// we're trying to parse (sizeof(type) * unit_count).
+	ErrNotEnoughData = errors.New("not enough data for type")
+
+	// ErrWrongType is used when we try to parse anything other than the
+	// current type.
+	ErrWrongType = errors.New("wrong type, can not parse")
+
+	// ErrUnhandledUnknownTag is used when we try to parse a tag that's
+	// recorded as an "unknown" type but not a documented tag (therefore
+	// leaving us not knowning how to read it).
+	ErrUnhandledUnknownTypedTag = errors.New("not a standard unknown-typed tag")
+)
+
+type Rational struct {
+	Numerator   uint32
+	Denominator uint32
+}
+
+type SignedRational struct {
+	Numerator   int32
+	Denominator int32
+}
+
+func TagTypeSize(tagType TagTypePrimitive) int {
+
+	// DEPRECATED(dustin): `(TagTypePrimitive).Size()` should be used, directly.
+
+	return tagType.Size()
+}
+
+// Format returns a stringified value for the given bytes. Automatically
+// calculates count based on type size.
+func Format(rawBytes []byte, tagType TagTypePrimitive, justFirst bool, byteOrder binary.ByteOrder) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! Add tests
+
+	typeSize := tagType.Size()
+
+	if len(rawBytes)%typeSize != 0 {
+		log.Panicf("byte-count (%d) does not align for [%s] type with a size of (%d) bytes", len(rawBytes), TypeNames[tagType], typeSize)
+	}
+
+	// unitCount is the calculated unit-count. This should equal the original
+	// value from the tag (pre-resolution).
+	unitCount := uint32(len(rawBytes) / typeSize)
+
+	// Truncate the items if it's not bytes or a string and we just want the first.
+
+	valueSuffix := ""
+	if justFirst == true && unitCount > 1 && tagType != TypeByte && tagType != TypeAscii && tagType != TypeAsciiNoNul {
+		unitCount = 1
+		valueSuffix = "..."
+	}
+
+	if tagType == TypeByte {
+		items, err := parser.ParseBytes(rawBytes, unitCount)
+		log.PanicIf(err)
+
+		return DumpBytesToString(items), nil
+	} else if tagType == TypeAscii {
+		phrase, err := parser.ParseAscii(rawBytes, unitCount)
+		log.PanicIf(err)
+
+		return phrase, nil
+	} else if tagType == TypeAsciiNoNul {
+		phrase, err := parser.ParseAsciiNoNul(rawBytes, unitCount)
+		log.PanicIf(err)
+
+		return phrase, nil
+	} else if tagType == TypeShort {
+		items, err := parser.ParseShorts(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+
+		if len(items) > 0 {
+			if justFirst == true {
+				return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
+			} else {
+				return fmt.Sprintf("%v", items), nil
+			}
+		} else {
+			return "", nil
+		}
+	} else if tagType == TypeLong {
+		items, err := parser.ParseLongs(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+
+		if len(items) > 0 {
+			if justFirst == true {
+				return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
+			} else {
+				return fmt.Sprintf("%v", items), nil
+			}
+		} else {
+			return "", nil
+		}
+	} else if tagType == TypeRational {
+		items, err := parser.ParseRationals(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+
+		if len(items) > 0 {
+			parts := make([]string, len(items))
+			for i, r := range items {
+				parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
+			}
+
+			if justFirst == true {
+				return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
+			} else {
+				return fmt.Sprintf("%v", parts), nil
+			}
+		} else {
+			return "", nil
+		}
+	} else if tagType == TypeSignedLong {
+		items, err := parser.ParseSignedLongs(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+
+		if len(items) > 0 {
+			if justFirst == true {
+				return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
+			} else {
+				return fmt.Sprintf("%v", items), nil
+			}
+		} else {
+			return "", nil
+		}
+	} else if tagType == TypeSignedRational {
+		items, err := parser.ParseSignedRationals(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+
+		parts := make([]string, len(items))
+		for i, r := range items {
+			parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
+		}
+
+		if len(items) > 0 {
+			if justFirst == true {
+				return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
+			} else {
+				return fmt.Sprintf("%v", parts), nil
+			}
+		} else {
+			return "", nil
+		}
+	} else {
+		// Affects only "unknown" values, in general.
+		log.Panicf("value of type [%s] can not be formatted into string", tagType.String())
+
+		// Never called.
+		return "", nil
+	}
+}
+
+func EncodeStringToBytes(tagType TagTypePrimitive, valueString string) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if tagType == TypeUndefined {
+		// TODO(dustin): Circle back to this.
+		log.Panicf("undefined-type values are not supported")
+	}
+
+	if tagType == TypeByte {
+		return []byte(valueString), nil
+	} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
+		// Whether or not we're putting an NUL on the end is only relevant for
+		// byte-level encoding. This function really just supports a user
+		// interface.
+
+		return valueString, nil
+	} else if tagType == TypeShort {
+		n, err := strconv.ParseUint(valueString, 10, 16)
+		log.PanicIf(err)
+
+		return uint16(n), nil
+	} else if tagType == TypeLong {
+		n, err := strconv.ParseUint(valueString, 10, 32)
+		log.PanicIf(err)
+
+		return uint32(n), nil
+	} else if tagType == TypeRational {
+		parts := strings.SplitN(valueString, "/", 2)
+
+		numerator, err := strconv.ParseUint(parts[0], 10, 32)
+		log.PanicIf(err)
+
+		denominator, err := strconv.ParseUint(parts[1], 10, 32)
+		log.PanicIf(err)
+
+		return Rational{
+			Numerator:   uint32(numerator),
+			Denominator: uint32(denominator),
+		}, nil
+	} else if tagType == TypeSignedLong {
+		n, err := strconv.ParseInt(valueString, 10, 32)
+		log.PanicIf(err)
+
+		return int32(n), nil
+	} else if tagType == TypeSignedRational {
+		parts := strings.SplitN(valueString, "/", 2)
+
+		numerator, err := strconv.ParseInt(parts[0], 10, 32)
+		log.PanicIf(err)
+
+		denominator, err := strconv.ParseInt(parts[1], 10, 32)
+		log.PanicIf(err)
+
+		return SignedRational{
+			Numerator:   int32(numerator),
+			Denominator: int32(denominator),
+		}, nil
+	}
+
+	log.Panicf("from-string encoding for type not supported; this shouldn't happen: [%s]", tagType.String())
+	return nil, nil
+}
+
+func init() {
+	for typeId, typeName := range TypeNames {
+		TypeNamesR[typeName] = typeId
+	}
+}

vendor/github.com/dsoprea/go-exif/type_encode.go

@@ -0,0 +1,262 @@
+package exif
+
+import (
+	"bytes"
+	"reflect"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	typeEncodeLogger = log.NewLogger("exif.type_encode")
+)
+
+// EncodedData encapsulates the compound output of an encoding operation.
+type EncodedData struct {
+	Type    TagTypePrimitive
+	Encoded []byte
+
+	// TODO(dustin): Is this really necessary? We might have this just to correlate to the incoming stream format (raw bytes and a unit-count both for incoming and outgoing).
+	UnitCount uint32
+}
+
+type ValueEncoder struct {
+	byteOrder binary.ByteOrder
+}
+
+func NewValueEncoder(byteOrder binary.ByteOrder) *ValueEncoder {
+	return &ValueEncoder{
+		byteOrder: byteOrder,
+	}
+}
+
+func (ve *ValueEncoder) encodeBytes(value []uint8) (ed EncodedData, err error) {
+	ed.Type = TypeByte
+	ed.Encoded = []byte(value)
+	ed.UnitCount = uint32(len(value))
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeAscii(value string) (ed EncodedData, err error) {
+	ed.Type = TypeAscii
+
+	ed.Encoded = []byte(value)
+	ed.Encoded = append(ed.Encoded, 0)
+
+	ed.UnitCount = uint32(len(ed.Encoded))
+
+	return ed, nil
+}
+
+// encodeAsciiNoNul returns a string encoded as a byte-string without a trailing
+// NUL byte.
+//
+// Note that:
+//
+// 1. This type can not be automatically encoded using `Encode()`. The default
+//    mode is to encode *with* a trailing NUL byte using `encodeAscii`. Only
+//    certain undefined-type tags using an unterminated ASCII string and these
+//    are exceptional in nature.
+//
+// 2. The presence of this method allows us to completely test the complimentary
+//    no-nul parser.
+//
+func (ve *ValueEncoder) encodeAsciiNoNul(value string) (ed EncodedData, err error) {
+	ed.Type = TypeAsciiNoNul
+	ed.Encoded = []byte(value)
+	ed.UnitCount = uint32(len(ed.Encoded))
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeShorts(value []uint16) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*2)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint16(ed.Encoded[i*2:(i+1)*2], value[i])
+	}
+
+	ed.Type = TypeShort
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeLongs(value []uint32) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*4)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint32(ed.Encoded[i*4:(i+1)*4], value[i])
+	}
+
+	ed.Type = TypeLong
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeRationals(value []Rational) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*8)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint32(ed.Encoded[i*8+0:i*8+4], value[i].Numerator)
+		ve.byteOrder.PutUint32(ed.Encoded[i*8+4:i*8+8], value[i].Denominator)
+	}
+
+	ed.Type = TypeRational
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeSignedLongs(value []int32) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+
+	b := bytes.NewBuffer(make([]byte, 0, 8*ed.UnitCount))
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		err := binary.Write(b, ve.byteOrder, value[i])
+		log.PanicIf(err)
+	}
+
+	ed.Type = TypeSignedLong
+	ed.Encoded = b.Bytes()
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeSignedRationals(value []SignedRational) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+
+	b := bytes.NewBuffer(make([]byte, 0, 8*ed.UnitCount))
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		err := binary.Write(b, ve.byteOrder, value[i].Numerator)
+		log.PanicIf(err)
+
+		err = binary.Write(b, ve.byteOrder, value[i].Denominator)
+		log.PanicIf(err)
+	}
+
+	ed.Type = TypeSignedRational
+	ed.Encoded = b.Bytes()
+
+	return ed, nil
+}
+
+// Encode returns bytes for the given value, infering type from the actual
+// value. This does not support `TypeAsciiNoNull` (all strings are encoded as
+// `TypeAscii`).
+func (ve *ValueEncoder) Encode(value interface{}) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): This is redundant with EncodeWithType. Refactor one to use the other.
+
+	switch value.(type) {
+	case []byte:
+		ed, err = ve.encodeBytes(value.([]byte))
+		log.PanicIf(err)
+	case string:
+		ed, err = ve.encodeAscii(value.(string))
+		log.PanicIf(err)
+	case []uint16:
+		ed, err = ve.encodeShorts(value.([]uint16))
+		log.PanicIf(err)
+	case []uint32:
+		ed, err = ve.encodeLongs(value.([]uint32))
+		log.PanicIf(err)
+	case []Rational:
+		ed, err = ve.encodeRationals(value.([]Rational))
+		log.PanicIf(err)
+	case []int32:
+		ed, err = ve.encodeSignedLongs(value.([]int32))
+		log.PanicIf(err)
+	case []SignedRational:
+		ed, err = ve.encodeSignedRationals(value.([]SignedRational))
+		log.PanicIf(err)
+	default:
+		log.Panicf("value not encodable: [%s] [%v]", reflect.TypeOf(value), value)
+	}
+
+	return ed, nil
+}
+
+// EncodeWithType returns bytes for the given value, using the given `TagType`
+// value to determine how to encode. This supports `TypeAsciiNoNul`.
+func (ve *ValueEncoder) EncodeWithType(tt TagType, value interface{}) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): This is redundant with Encode. Refactor one to use the other.
+
+	switch tt.Type() {
+	case TypeByte:
+		ed, err = ve.encodeBytes(value.([]byte))
+		log.PanicIf(err)
+	case TypeAscii:
+		ed, err = ve.encodeAscii(value.(string))
+		log.PanicIf(err)
+	case TypeAsciiNoNul:
+		ed, err = ve.encodeAsciiNoNul(value.(string))
+		log.PanicIf(err)
+	case TypeShort:
+		ed, err = ve.encodeShorts(value.([]uint16))
+		log.PanicIf(err)
+	case TypeLong:
+		ed, err = ve.encodeLongs(value.([]uint32))
+		log.PanicIf(err)
+	case TypeRational:
+		ed, err = ve.encodeRationals(value.([]Rational))
+		log.PanicIf(err)
+	case TypeSignedLong:
+		ed, err = ve.encodeSignedLongs(value.([]int32))
+		log.PanicIf(err)
+	case TypeSignedRational:
+		ed, err = ve.encodeSignedRationals(value.([]SignedRational))
+		log.PanicIf(err)
+	default:
+		log.Panicf("value not encodable (with type): %v [%v]", tt, value)
+	}
+
+	return ed, nil
+}

vendor/github.com/dsoprea/go-exif/utility.go

@@ -0,0 +1,222 @@
+package exif
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/dsoprea/go-logging"
+)
+
+func DumpBytes(data []byte) {
+	fmt.Printf("DUMP: ")
+	for _, x := range data {
+		fmt.Printf("%02x ", x)
+	}
+
+	fmt.Printf("\n")
+}
+
+func DumpBytesClause(data []byte) {
+	fmt.Printf("DUMP: ")
+
+	fmt.Printf("[]byte { ")
+
+	for i, x := range data {
+		fmt.Printf("0x%02x", x)
+
+		if i < len(data)-1 {
+			fmt.Printf(", ")
+		}
+	}
+
+	fmt.Printf(" }\n")
+}
+
+func DumpBytesToString(data []byte) string {
+	b := new(bytes.Buffer)
+
+	for i, x := range data {
+		_, err := b.WriteString(fmt.Sprintf("%02x", x))
+		log.PanicIf(err)
+
+		if i < len(data)-1 {
+			_, err := b.WriteRune(' ')
+			log.PanicIf(err)
+		}
+	}
+
+	return b.String()
+}
+
+func DumpBytesClauseToString(data []byte) string {
+	b := new(bytes.Buffer)
+
+	for i, x := range data {
+		_, err := b.WriteString(fmt.Sprintf("0x%02x", x))
+		log.PanicIf(err)
+
+		if i < len(data)-1 {
+			_, err := b.WriteString(", ")
+			log.PanicIf(err)
+		}
+	}
+
+	return b.String()
+}
+
+// ParseExifFullTimestamp parses dates like "2018:11:30 13:01:49" into a UTC
+// `time.Time` struct.
+func ParseExifFullTimestamp(fullTimestampPhrase string) (timestamp time.Time, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	parts := strings.Split(fullTimestampPhrase, " ")
+	datestampValue, timestampValue := parts[0], parts[1]
+
+	dateParts := strings.Split(datestampValue, ":")
+
+	year, err := strconv.ParseUint(dateParts[0], 10, 16)
+	if err != nil {
+		log.Panicf("could not parse year")
+	}
+
+	month, err := strconv.ParseUint(dateParts[1], 10, 8)
+	if err != nil {
+		log.Panicf("could not parse month")
+	}
+
+	day, err := strconv.ParseUint(dateParts[2], 10, 8)
+	if err != nil {
+		log.Panicf("could not parse day")
+	}
+
+	timeParts := strings.Split(timestampValue, ":")
+
+	hour, err := strconv.ParseUint(timeParts[0], 10, 8)
+	if err != nil {
+		log.Panicf("could not parse hour")
+	}
+
+	minute, err := strconv.ParseUint(timeParts[1], 10, 8)
+	if err != nil {
+		log.Panicf("could not parse minute")
+	}
+
+	second, err := strconv.ParseUint(timeParts[2], 10, 8)
+	if err != nil {
+		log.Panicf("could not parse second")
+	}
+
+	timestamp = time.Date(int(year), time.Month(month), int(day), int(hour), int(minute), int(second), 0, time.UTC)
+	return timestamp, nil
+}
+
+// ExifFullTimestampString produces a string like "2018:11:30 13:01:49" from a
+// `time.Time` struct. It will attempt to convert to UTC first.
+func ExifFullTimestampString(t time.Time) (fullTimestampPhrase string) {
+	t = t.UTC()
+
+	return fmt.Sprintf("%04d:%02d:%02d %02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
+}
+
+// ExifTag is one simple representation of a tag in a flat list of all of them.
+type ExifTag struct {
+	IfdPath string `json:"ifd_path"`
+
+	TagId   uint16 `json:"id"`
+	TagName string `json:"name"`
+
+	TagTypeId   TagTypePrimitive `json:"type_id"`
+	TagTypeName string           `json:"type_name"`
+	Value       interface{}      `json:"value"`
+	ValueBytes  []byte           `json:"value_bytes"`
+
+	ChildIfdPath string `json:"child_ifd_path"`
+}
+
+// String returns a string representation.
+func (et ExifTag) String() string {
+	return fmt.Sprintf("ExifTag<IFD-PATH=[%s] TAG-ID=(0x%02x) TAG-NAME=[%s] TAG-TYPE=[%s] VALUE=[%v] VALUE-BYTES=(%d) CHILD-IFD-PATH=[%s]", et.IfdPath, et.TagId, et.TagName, et.TagTypeName, et.Value, len(et.ValueBytes), et.ChildIfdPath)
+}
+
+// GetFlatExifData returns a simple, flat representation of all tags.
+func GetFlatExifData(exifData []byte) (exifTags []ExifTag, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	im := NewIfdMappingWithStandard()
+	ti := NewTagIndex()
+
+	_, index, err := Collect(im, ti, exifData)
+	log.PanicIf(err)
+
+	q := []*Ifd{index.RootIfd}
+
+	exifTags = make([]ExifTag, 0)
+
+	for len(q) > 0 {
+		var ifd *Ifd
+		ifd, q = q[0], q[1:]
+
+		ti := NewTagIndex()
+		for _, ite := range ifd.Entries {
+			tagName := ""
+
+			it, err := ti.Get(ifd.IfdPath, ite.TagId)
+			if err != nil {
+				// If it's a non-standard tag, just leave the name blank.
+				if log.Is(err, ErrTagNotFound) != true {
+					log.PanicIf(err)
+				}
+			} else {
+				tagName = it.Name
+			}
+
+			value, err := ifd.TagValue(ite)
+			if err != nil {
+				if err == ErrUnhandledUnknownTypedTag {
+					value = UnparseableUnknownTagValuePlaceholder
+				} else {
+					log.Panic(err)
+				}
+			}
+
+			valueBytes, err := ifd.TagValueBytes(ite)
+			if err != nil && err != ErrUnhandledUnknownTypedTag {
+				log.Panic(err)
+			}
+
+			et := ExifTag{
+				IfdPath:      ifd.IfdPath,
+				TagId:        ite.TagId,
+				TagName:      tagName,
+				TagTypeId:    ite.TagType,
+				TagTypeName:  TypeNames[ite.TagType],
+				Value:        value,
+				ValueBytes:   valueBytes,
+				ChildIfdPath: ite.ChildIfdPath,
+			}
+
+			exifTags = append(exifTags, et)
+		}
+
+		for _, childIfd := range ifd.Children {
+			q = append(q, childIfd)
+		}
+
+		if ifd.NextIfd != nil {
+			q = append(q, ifd.NextIfd)
+		}
+	}
+
+	return exifTags, nil
+}

vendor/github.com/dsoprea/go-exif/v2/LICENSE

@@ -0,0 +1,9 @@
+MIT LICENSE
+
+Copyright 2019 Dustin Oprea
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/dsoprea/go-exif/v2/common/ifd.go

@@ -0,0 +1,659 @@
+package exifcommon
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	ifdLogger = log.NewLogger("exifcommon.ifd")
+)
+
+var (
+	ErrChildIfdNotMapped = errors.New("no child-IFD for that tag-ID under parent")
+)
+
+// MappedIfd is one node in the IFD-mapping.
+type MappedIfd struct {
+	ParentTagId uint16
+	Placement   []uint16
+	Path        []string
+
+	Name     string
+	TagId    uint16
+	Children map[uint16]*MappedIfd
+}
+
+// String returns a descriptive string.
+func (mi *MappedIfd) String() string {
+	pathPhrase := mi.PathPhrase()
+	return fmt.Sprintf("MappedIfd<(0x%04X) [%s] PATH=[%s]>", mi.TagId, mi.Name, pathPhrase)
+}
+
+// PathPhrase returns a non-fully-qualified IFD path.
+func (mi *MappedIfd) PathPhrase() string {
+	return strings.Join(mi.Path, "/")
+}
+
+// TODO(dustin): Refactor this to use IfdIdentity structs.
+
+// IfdMapping describes all of the IFDs that we currently recognize.
+type IfdMapping struct {
+	rootNode *MappedIfd
+}
+
+// NewIfdMapping returns a new IfdMapping struct.
+func NewIfdMapping() (ifdMapping *IfdMapping) {
+	rootNode := &MappedIfd{
+		Path:     make([]string, 0),
+		Children: make(map[uint16]*MappedIfd),
+	}
+
+	return &IfdMapping{
+		rootNode: rootNode,
+	}
+}
+
+// NewIfdMappingWithStandard retruns a new IfdMapping struct preloaded with the
+// standard IFDs.
+func NewIfdMappingWithStandard() (ifdMapping *IfdMapping) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	im := NewIfdMapping()
+
+	err := LoadStandardIfds(im)
+	log.PanicIf(err)
+
+	return im
+}
+
+// Get returns the node given the path slice.
+func (im *IfdMapping) Get(parentPlacement []uint16) (childIfd *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ptr := im.rootNode
+	for _, tagId := range parentPlacement {
+		if descendantPtr, found := ptr.Children[tagId]; found == false {
+			log.Panicf("ifd child with tag-ID (%04x) not registered: [%s]", tagId, ptr.PathPhrase())
+		} else {
+			ptr = descendantPtr
+		}
+	}
+
+	return ptr, nil
+}
+
+// GetWithPath returns the node given the path string.
+func (im *IfdMapping) GetWithPath(pathPhrase string) (mi *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if pathPhrase == "" {
+		log.Panicf("path-phrase is empty")
+	}
+
+	path := strings.Split(pathPhrase, "/")
+	ptr := im.rootNode
+
+	for _, name := range path {
+		var hit *MappedIfd
+		for _, mi := range ptr.Children {
+			if mi.Name == name {
+				hit = mi
+				break
+			}
+		}
+
+		if hit == nil {
+			log.Panicf("ifd child with name [%s] not registered: [%s]", name, ptr.PathPhrase())
+		}
+
+		ptr = hit
+	}
+
+	return ptr, nil
+}
+
+// GetChild is a convenience function to get the child path for a given parent
+// placement and child tag-ID.
+func (im *IfdMapping) GetChild(parentPathPhrase string, tagId uint16) (mi *MappedIfd, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	mi, err = im.GetWithPath(parentPathPhrase)
+	log.PanicIf(err)
+
+	for _, childMi := range mi.Children {
+		if childMi.TagId == tagId {
+			return childMi, nil
+		}
+	}
+
+	// Whether or not an IFD is defined in data, such an IFD is not registered
+	// and would be unknown.
+	log.Panic(ErrChildIfdNotMapped)
+	return nil, nil
+}
+
+// IfdTagIdAndIndex represents a specific part of the IFD path.
+//
+// This is a legacy type.
+type IfdTagIdAndIndex struct {
+	Name  string
+	TagId uint16
+	Index int
+}
+
+// String returns a descriptive string.
+func (itii IfdTagIdAndIndex) String() string {
+	return fmt.Sprintf("IfdTagIdAndIndex<NAME=[%s] ID=(%04x) INDEX=(%d)>", itii.Name, itii.TagId, itii.Index)
+}
+
+// ResolvePath takes a list of names, which can also be suffixed with indices
+// (to identify the second, third, etc.. sibling IFD) and returns a list of
+// tag-IDs and those indices.
+//
+// Example:
+//
+// - IFD/Exif/Iop
+// - IFD0/Exif/Iop
+//
+// This is the only call that supports adding the numeric indices.
+func (im *IfdMapping) ResolvePath(pathPhrase string) (lineage []IfdTagIdAndIndex, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	pathPhrase = strings.TrimSpace(pathPhrase)
+
+	if pathPhrase == "" {
+		log.Panicf("can not resolve empty path-phrase")
+	}
+
+	path := strings.Split(pathPhrase, "/")
+	lineage = make([]IfdTagIdAndIndex, len(path))
+
+	ptr := im.rootNode
+	empty := IfdTagIdAndIndex{}
+	for i, name := range path {
+		indexByte := name[len(name)-1]
+		index := 0
+		if indexByte >= '0' && indexByte <= '9' {
+			index = int(indexByte - '0')
+			name = name[:len(name)-1]
+		}
+
+		itii := IfdTagIdAndIndex{}
+		for _, mi := range ptr.Children {
+			if mi.Name != name {
+				continue
+			}
+
+			itii.Name = name
+			itii.TagId = mi.TagId
+			itii.Index = index
+
+			ptr = mi
+
+			break
+		}
+
+		if itii == empty {
+			log.Panicf("ifd child with name [%s] not registered: [%s]", name, pathPhrase)
+		}
+
+		lineage[i] = itii
+	}
+
+	return lineage, nil
+}
+
+// FqPathPhraseFromLineage returns the fully-qualified IFD path from the slice.
+func (im *IfdMapping) FqPathPhraseFromLineage(lineage []IfdTagIdAndIndex) (fqPathPhrase string) {
+	fqPathParts := make([]string, len(lineage))
+	for i, itii := range lineage {
+		if itii.Index > 0 {
+			fqPathParts[i] = fmt.Sprintf("%s%d", itii.Name, itii.Index)
+		} else {
+			fqPathParts[i] = itii.Name
+		}
+	}
+
+	return strings.Join(fqPathParts, "/")
+}
+
+// PathPhraseFromLineage returns the non-fully-qualified IFD path from the
+// slice.
+func (im *IfdMapping) PathPhraseFromLineage(lineage []IfdTagIdAndIndex) (pathPhrase string) {
+	pathParts := make([]string, len(lineage))
+	for i, itii := range lineage {
+		pathParts[i] = itii.Name
+	}
+
+	return strings.Join(pathParts, "/")
+}
+
+// StripPathPhraseIndices returns a non-fully-qualified path-phrase (no
+// indices).
+func (im *IfdMapping) StripPathPhraseIndices(pathPhrase string) (strippedPathPhrase string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	lineage, err := im.ResolvePath(pathPhrase)
+	log.PanicIf(err)
+
+	strippedPathPhrase = im.PathPhraseFromLineage(lineage)
+	return strippedPathPhrase, nil
+}
+
+// Add puts the given IFD at the given position of the tree. The position of the
+// tree is referred to as the placement and is represented by a set of tag-IDs,
+// where the leftmost is the root tag and the tags going to the right are
+// progressive descendants.
+func (im *IfdMapping) Add(parentPlacement []uint16, tagId uint16, name string) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! It would be nicer to provide a list of names in the placement rather than tag-IDs.
+
+	ptr, err := im.Get(parentPlacement)
+	log.PanicIf(err)
+
+	path := make([]string, len(parentPlacement)+1)
+	if len(parentPlacement) > 0 {
+		copy(path, ptr.Path)
+	}
+
+	path[len(path)-1] = name
+
+	placement := make([]uint16, len(parentPlacement)+1)
+	if len(placement) > 0 {
+		copy(placement, ptr.Placement)
+	}
+
+	placement[len(placement)-1] = tagId
+
+	childIfd := &MappedIfd{
+		ParentTagId: ptr.TagId,
+		Path:        path,
+		Placement:   placement,
+		Name:        name,
+		TagId:       tagId,
+		Children:    make(map[uint16]*MappedIfd),
+	}
+
+	if _, found := ptr.Children[tagId]; found == true {
+		log.Panicf("child IFD with tag-ID (%04x) already registered under IFD [%s] with tag-ID (%04x)", tagId, ptr.Name, ptr.TagId)
+	}
+
+	ptr.Children[tagId] = childIfd
+
+	return nil
+}
+
+func (im *IfdMapping) dumpLineages(stack []*MappedIfd, input []string) (output []string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	currentIfd := stack[len(stack)-1]
+
+	output = input
+	for _, childIfd := range currentIfd.Children {
+		stackCopy := make([]*MappedIfd, len(stack)+1)
+
+		copy(stackCopy, stack)
+		stackCopy[len(stack)] = childIfd
+
+		// Add to output, but don't include the obligatory root node.
+		parts := make([]string, len(stackCopy)-1)
+		for i, mi := range stackCopy[1:] {
+			parts[i] = mi.Name
+		}
+
+		output = append(output, strings.Join(parts, "/"))
+
+		output, err = im.dumpLineages(stackCopy, output)
+		log.PanicIf(err)
+	}
+
+	return output, nil
+}
+
+// DumpLineages returns a slice of strings representing all mappings.
+func (im *IfdMapping) DumpLineages() (output []string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	stack := []*MappedIfd{im.rootNode}
+	output = make([]string, 0)
+
+	output, err = im.dumpLineages(stack, output)
+	log.PanicIf(err)
+
+	return output, nil
+}
+
+// LoadStandardIfds loads the standard IFDs into the mapping.
+func LoadStandardIfds(im *IfdMapping) (err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	err = im.Add(
+		[]uint16{},
+		IfdStandardIfdIdentity.TagId(), IfdStandardIfdIdentity.Name())
+
+	log.PanicIf(err)
+
+	err = im.Add(
+		[]uint16{IfdStandardIfdIdentity.TagId()},
+		IfdExifStandardIfdIdentity.TagId(), IfdExifStandardIfdIdentity.Name())
+
+	log.PanicIf(err)
+
+	err = im.Add(
+		[]uint16{IfdStandardIfdIdentity.TagId(), IfdExifStandardIfdIdentity.TagId()},
+		IfdExifIopStandardIfdIdentity.TagId(), IfdExifIopStandardIfdIdentity.Name())
+
+	log.PanicIf(err)
+
+	err = im.Add(
+		[]uint16{IfdStandardIfdIdentity.TagId()},
+		IfdGpsInfoStandardIfdIdentity.TagId(), IfdGpsInfoStandardIfdIdentity.Name())
+
+	log.PanicIf(err)
+
+	return nil
+}
+
+// IfdTag describes a single IFD tag and its parent (if any).
+type IfdTag struct {
+	parentIfdTag *IfdTag
+	tagId        uint16
+	name         string
+}
+
+func NewIfdTag(parentIfdTag *IfdTag, tagId uint16, name string) IfdTag {
+	return IfdTag{
+		parentIfdTag: parentIfdTag,
+		tagId:        tagId,
+		name:         name,
+	}
+}
+
+// ParentIfd returns the IfdTag of this IFD's parent.
+func (it IfdTag) ParentIfd() *IfdTag {
+	return it.parentIfdTag
+}
+
+// TagId returns the tag-ID of this IFD.
+func (it IfdTag) TagId() uint16 {
+	return it.tagId
+}
+
+// Name returns the simple name of this IFD.
+func (it IfdTag) Name() string {
+	return it.name
+}
+
+// String returns a descriptive string.
+func (it IfdTag) String() string {
+	parentIfdPhrase := ""
+	if it.parentIfdTag != nil {
+		parentIfdPhrase = fmt.Sprintf(" PARENT=(0x%04x)[%s]", it.parentIfdTag.tagId, it.parentIfdTag.name)
+	}
+
+	return fmt.Sprintf("IfdTag<TAG-ID=(0x%04x) NAME=[%s]%s>", it.tagId, it.name, parentIfdPhrase)
+}
+
+var (
+	// rootStandardIfd is the standard root IFD.
+	rootStandardIfd = NewIfdTag(nil, 0x0000, "IFD") // IFD
+
+	// exifStandardIfd is the standard "Exif" IFD.
+	exifStandardIfd = NewIfdTag(&rootStandardIfd, 0x8769, "Exif") // IFD/Exif
+
+	// iopStandardIfd is the standard "Iop" IFD.
+	iopStandardIfd = NewIfdTag(&exifStandardIfd, 0xA005, "Iop") // IFD/Exif/Iop
+
+	// gpsInfoStandardIfd is the standard "GPS" IFD.
+	gpsInfoStandardIfd = NewIfdTag(&rootStandardIfd, 0x8825, "GPSInfo") // IFD/GPSInfo
+)
+
+// IfdIdentityPart represents one component in an IFD path.
+type IfdIdentityPart struct {
+	Name  string
+	Index int
+}
+
+// String returns a fully-qualified IFD path.
+func (iip IfdIdentityPart) String() string {
+	if iip.Index > 0 {
+		return fmt.Sprintf("%s%d", iip.Name, iip.Index)
+	} else {
+		return iip.Name
+	}
+}
+
+// UnindexedString returned a non-fully-qualified IFD path.
+func (iip IfdIdentityPart) UnindexedString() string {
+	return iip.Name
+}
+
+// IfdIdentity represents a single IFD path and provides access to various
+// information and representations.
+//
+// Only global instances can be used for equality checks.
+type IfdIdentity struct {
+	ifdTag    IfdTag
+	parts     []IfdIdentityPart
+	ifdPath   string
+	fqIfdPath string
+}
+
+// NewIfdIdentity returns a new IfdIdentity struct.
+func NewIfdIdentity(ifdTag IfdTag, parts ...IfdIdentityPart) (ii *IfdIdentity) {
+	ii = &IfdIdentity{
+		ifdTag: ifdTag,
+		parts:  parts,
+	}
+
+	ii.ifdPath = ii.getIfdPath()
+	ii.fqIfdPath = ii.getFqIfdPath()
+
+	return ii
+}
+
+// NewIfdIdentityFromString parses a string like "IFD/Exif" or "IFD1" or
+// something more exotic with custom IFDs ("SomeIFD4/SomeChildIFD6"). Note that
+// this will valid the unindexed IFD structure (because the standard tags from
+// the specification are unindexed), but not, obviously, any indices (e.g.
+// the numbers in "IFD0", "IFD1", "SomeIFD4/SomeChildIFD6"). It is
+// required for the caller to check whether these specific instances
+// were actually parsed out of the stream.
+func NewIfdIdentityFromString(im *IfdMapping, fqIfdPath string) (ii *IfdIdentity, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	lineage, err := im.ResolvePath(fqIfdPath)
+	log.PanicIf(err)
+
+	var lastIt *IfdTag
+	identityParts := make([]IfdIdentityPart, len(lineage))
+	for i, itii := range lineage {
+		// Build out the tag that will eventually point to the IFD represented
+		// by the right-most part in the IFD path.
+
+		it := &IfdTag{
+			parentIfdTag: lastIt,
+			tagId:        itii.TagId,
+			name:         itii.Name,
+		}
+
+		lastIt = it
+
+		// Create the next IfdIdentity part.
+
+		iip := IfdIdentityPart{
+			Name:  itii.Name,
+			Index: itii.Index,
+		}
+
+		identityParts[i] = iip
+	}
+
+	ii = NewIfdIdentity(*lastIt, identityParts...)
+	return ii, nil
+}
+
+func (ii *IfdIdentity) getFqIfdPath() string {
+	partPhrases := make([]string, len(ii.parts))
+	for i, iip := range ii.parts {
+		partPhrases[i] = iip.String()
+	}
+
+	return strings.Join(partPhrases, "/")
+}
+
+func (ii *IfdIdentity) getIfdPath() string {
+	partPhrases := make([]string, len(ii.parts))
+	for i, iip := range ii.parts {
+		partPhrases[i] = iip.UnindexedString()
+	}
+
+	return strings.Join(partPhrases, "/")
+}
+
+// String returns a fully-qualified IFD path.
+func (ii *IfdIdentity) String() string {
+	return ii.fqIfdPath
+}
+
+// UnindexedString returns a non-fully-qualified IFD path.
+func (ii *IfdIdentity) UnindexedString() string {
+	return ii.ifdPath
+}
+
+// IfdTag returns the tag struct behind this IFD.
+func (ii *IfdIdentity) IfdTag() IfdTag {
+	return ii.ifdTag
+}
+
+// TagId returns the tag-ID of the IFD.
+func (ii *IfdIdentity) TagId() uint16 {
+	return ii.ifdTag.TagId()
+}
+
+// LeafPathPart returns the last right-most path-part, which represents the
+// current IFD.
+func (ii *IfdIdentity) LeafPathPart() IfdIdentityPart {
+	return ii.parts[len(ii.parts)-1]
+}
+
+// Name returns the simple name of this IFD.
+func (ii *IfdIdentity) Name() string {
+	return ii.LeafPathPart().Name
+}
+
+// Index returns the index of this IFD (more then one IFD under a parent IFD
+// will be numbered [0..n]).
+func (ii *IfdIdentity) Index() int {
+	return ii.LeafPathPart().Index
+}
+
+// Equals returns true if the two IfdIdentity instances are effectively
+// identical.
+//
+// Since there's no way to get a specific fully-qualified IFD path without a
+// certain slice of parts and all other fields are also derived from this,
+// checking that the fully-qualified IFD path is equals is sufficient.
+func (ii *IfdIdentity) Equals(ii2 *IfdIdentity) bool {
+	return ii.String() == ii2.String()
+}
+
+// NewChild creates an IfdIdentity for an IFD that is a child of the current
+// IFD.
+func (ii *IfdIdentity) NewChild(childIfdTag IfdTag, index int) (iiChild *IfdIdentity) {
+	if *childIfdTag.parentIfdTag != ii.ifdTag {
+		log.Panicf("can not add child; we are not the parent:\nUS=%v\nCHILD=%v", ii.ifdTag, childIfdTag)
+	}
+
+	childPart := IfdIdentityPart{childIfdTag.name, index}
+	childParts := append(ii.parts, childPart)
+
+	iiChild = NewIfdIdentity(childIfdTag, childParts...)
+	return iiChild
+}
+
+// NewSibling creates an IfdIdentity for an IFD that is a sibling to the current
+// one.
+func (ii *IfdIdentity) NewSibling(index int) (iiSibling *IfdIdentity) {
+	parts := make([]IfdIdentityPart, len(ii.parts))
+
+	copy(parts, ii.parts)
+	parts[len(parts)-1].Index = index
+
+	iiSibling = NewIfdIdentity(ii.ifdTag, parts...)
+	return iiSibling
+}
+
+var (
+	// IfdStandardIfdIdentity represents the IFD path for IFD0.
+	IfdStandardIfdIdentity = NewIfdIdentity(rootStandardIfd, IfdIdentityPart{"IFD", 0})
+
+	// IfdExifStandardIfdIdentity represents the IFD path for IFD0/Exif0.
+	IfdExifStandardIfdIdentity = IfdStandardIfdIdentity.NewChild(exifStandardIfd, 0)
+
+	// IfdExifIopStandardIfdIdentity represents the IFD path for IFD0/Exif0/Iop0.
+	IfdExifIopStandardIfdIdentity = IfdExifStandardIfdIdentity.NewChild(iopStandardIfd, 0)
+
+	// IfdGPSInfoStandardIfdIdentity represents the IFD path for IFD0/GPSInfo0.
+	IfdGpsInfoStandardIfdIdentity = IfdStandardIfdIdentity.NewChild(gpsInfoStandardIfd, 0)
+
+	// Ifd1StandardIfdIdentity represents the IFD path for IFD1.
+	Ifd1StandardIfdIdentity = NewIfdIdentity(rootStandardIfd, IfdIdentityPart{"IFD", 1})
+)
+
+var (
+	IfdPathStandard        = IfdStandardIfdIdentity
+	IfdPathStandardExif    = IfdExifStandardIfdIdentity
+	IfdPathStandardExifIop = IfdExifIopStandardIfdIdentity
+	IfdPathStandardGps     = IfdGpsInfoStandardIfdIdentity
+)

vendor/github.com/dsoprea/go-exif/v2/common/parser.go

@@ -0,0 +1,219 @@
+package exifcommon
+
+import (
+	"bytes"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	parserLogger = log.NewLogger("exifcommon.parser")
+)
+
+// Parser knows how to parse all well-defined, encoded EXIF types.
+type Parser struct {
+}
+
+// ParseBytesknows how to parse a byte-type value.
+func (p *Parser) ParseBytes(data []byte, unitCount uint32) (value []uint8, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeByte.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = []uint8(data[:count])
+
+	return value, nil
+}
+
+// ParseAscii returns a string and auto-strips the trailing NUL character that
+// should be at the end of the encoding.
+func (p *Parser) ParseAscii(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	if len(data) == 0 || data[count-1] != 0 {
+		s := string(data[:count])
+		parserLogger.Warningf(nil, "ascii not terminated with nul as expected: [%v]", s)
+
+		return s, nil
+	}
+
+	// Auto-strip the NUL from the end. It serves no purpose outside of
+	// encoding semantics.
+
+	return string(data[:count-1]), nil
+}
+
+// ParseAsciiNoNul returns a string without any consideration for a trailing NUL
+// character.
+func (p *Parser) ParseAsciiNoNul(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	return string(data[:count]), nil
+}
+
+// ParseShorts knows how to parse an encoded list of shorts.
+func (p *Parser) ParseShorts(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeShort.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint16, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint16(data[i*2:])
+	}
+
+	return value, nil
+}
+
+// ParseLongs knows how to encode an encoded list of unsigned longs.
+func (p *Parser) ParseLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint32, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint32(data[i*4:])
+	}
+
+	return value, nil
+}
+
+// ParseRationals knows how to parse an encoded list of unsigned rationals.
+func (p *Parser) ParseRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]Rational, count)
+	for i := 0; i < count; i++ {
+		value[i].Numerator = byteOrder.Uint32(data[i*8:])
+		value[i].Denominator = byteOrder.Uint32(data[i*8+4:])
+	}
+
+	return value, nil
+}
+
+// ParseSignedLongs knows how to parse an encoded list of signed longs.
+func (p *Parser) ParseSignedLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]int32, count)
+	for i := 0; i < count; i++ {
+		err := binary.Read(b, byteOrder, &value[i])
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// ParseSignedRationals knows how to parse an encoded list of signed
+// rationals.
+func (p *Parser) ParseSignedRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]SignedRational, count)
+	for i := 0; i < count; i++ {
+		err = binary.Read(b, byteOrder, &value[i].Numerator)
+		log.PanicIf(err)
+
+		err = binary.Read(b, byteOrder, &value[i].Denominator)
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}

vendor/github.com/dsoprea/go-exif/v2/common/testing_common.go

@@ -0,0 +1,88 @@
+package exifcommon
+
+import (
+	"os"
+	"path"
+
+	"encoding/binary"
+	"io/ioutil"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	moduleRootPath = ""
+
+	testExifData []byte = nil
+
+	// EncodeDefaultByteOrder is the default byte-order for encoding operations.
+	EncodeDefaultByteOrder = binary.BigEndian
+
+	// Default byte order for tests.
+	TestDefaultByteOrder = binary.BigEndian
+)
+
+func GetModuleRootPath() string {
+	if moduleRootPath == "" {
+		moduleRootPath = os.Getenv("EXIF_MODULE_ROOT_PATH")
+		if moduleRootPath != "" {
+			return moduleRootPath
+		}
+
+		currentWd, err := os.Getwd()
+		log.PanicIf(err)
+
+		currentPath := currentWd
+
+		visited := make([]string, 0)
+
+		for {
+			tryStampFilepath := path.Join(currentPath, ".MODULE_ROOT")
+
+			_, err := os.Stat(tryStampFilepath)
+			if err != nil && os.IsNotExist(err) != true {
+				log.Panic(err)
+			} else if err == nil {
+				break
+			}
+
+			visited = append(visited, tryStampFilepath)
+
+			currentPath = path.Dir(currentPath)
+			if currentPath == "/" {
+				log.Panicf("could not find module-root: %v", visited)
+			}
+		}
+
+		moduleRootPath = currentPath
+	}
+
+	return moduleRootPath
+}
+
+func GetTestAssetsPath() string {
+	moduleRootPath := GetModuleRootPath()
+	assetsPath := path.Join(moduleRootPath, "assets")
+
+	return assetsPath
+}
+
+func getTestImageFilepath() string {
+	assetsPath := GetTestAssetsPath()
+	testImageFilepath := path.Join(assetsPath, "NDM_8901.jpg")
+	return testImageFilepath
+}
+
+func getTestExifData() []byte {
+	if testExifData == nil {
+		assetsPath := GetTestAssetsPath()
+		filepath := path.Join(assetsPath, "NDM_8901.jpg.exif")
+
+		var err error
+
+		testExifData, err = ioutil.ReadFile(filepath)
+		log.PanicIf(err)
+	}
+
+	return testExifData
+}

vendor/github.com/dsoprea/go-exif/v2/common/type.go

@@ -0,0 +1,452 @@
+package exifcommon
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	typeLogger = log.NewLogger("exif.type")
+)
+
+var (
+	// ErrNotEnoughData is used when there isn't enough data to accommodate what
+	// we're trying to parse (sizeof(type) * unit_count).
+	ErrNotEnoughData = errors.New("not enough data for type")
+
+	// ErrWrongType is used when we try to parse anything other than the
+	// current type.
+	ErrWrongType = errors.New("wrong type, can not parse")
+
+	// ErrUnhandledUndefinedTypedTag is used when we try to parse a tag that's
+	// recorded as an "unknown" type but not a documented tag (therefore
+	// leaving us not knowning how to read it).
+	ErrUnhandledUndefinedTypedTag = errors.New("not a standard unknown-typed tag")
+)
+
+// TagTypePrimitive is a type-alias that let's us easily lookup type properties.
+type TagTypePrimitive uint16
+
+const (
+	// TypeByte describes an encoded list of bytes.
+	TypeByte TagTypePrimitive = 1
+
+	// TypeAscii describes an encoded list of characters that is terminated
+	// with a NUL in its encoded form.
+	TypeAscii TagTypePrimitive = 2
+
+	// TypeShort describes an encoded list of shorts.
+	TypeShort TagTypePrimitive = 3
+
+	// TypeLong describes an encoded list of longs.
+	TypeLong TagTypePrimitive = 4
+
+	// TypeRational describes an encoded list of rationals.
+	TypeRational TagTypePrimitive = 5
+
+	// TypeUndefined describes an encoded value that has a complex/non-clearcut
+	// interpretation.
+	TypeUndefined TagTypePrimitive = 7
+
+	// We've seen type-8, but have no documentation on it.
+
+	// TypeSignedLong describes an encoded list of signed longs.
+	TypeSignedLong TagTypePrimitive = 9
+
+	// TypeSignedRational describes an encoded list of signed rationals.
+	TypeSignedRational TagTypePrimitive = 10
+
+	// TypeAsciiNoNul is just a pseudo-type, for our own purposes.
+	TypeAsciiNoNul TagTypePrimitive = 0xf0
+)
+
+// String returns the name of the type
+func (typeType TagTypePrimitive) String() string {
+	return TypeNames[typeType]
+}
+
+// Size returns the size of one atomic unit of the type.
+func (tagType TagTypePrimitive) Size() int {
+	if tagType == TypeByte {
+		return 1
+	} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
+		return 1
+	} else if tagType == TypeShort {
+		return 2
+	} else if tagType == TypeLong {
+		return 4
+	} else if tagType == TypeRational {
+		return 8
+	} else if tagType == TypeSignedLong {
+		return 4
+	} else if tagType == TypeSignedRational {
+		return 8
+	} else {
+		log.Panicf("can not determine tag-value size for type (%d): [%s]", tagType, TypeNames[tagType])
+
+		// Never called.
+		return 0
+	}
+}
+
+// IsValid returns true if tagType is a valid type.
+func (tagType TagTypePrimitive) IsValid() bool {
+
+	// TODO(dustin): Add test
+
+	return tagType == TypeByte ||
+		tagType == TypeAscii ||
+		tagType == TypeAsciiNoNul ||
+		tagType == TypeShort ||
+		tagType == TypeLong ||
+		tagType == TypeRational ||
+		tagType == TypeSignedLong ||
+		tagType == TypeSignedRational ||
+		tagType == TypeUndefined
+}
+
+var (
+	// TODO(dustin): Rename TypeNames() to typeNames() and add getter.
+	TypeNames = map[TagTypePrimitive]string{
+		TypeByte:           "BYTE",
+		TypeAscii:          "ASCII",
+		TypeShort:          "SHORT",
+		TypeLong:           "LONG",
+		TypeRational:       "RATIONAL",
+		TypeUndefined:      "UNDEFINED",
+		TypeSignedLong:     "SLONG",
+		TypeSignedRational: "SRATIONAL",
+
+		TypeAsciiNoNul: "_ASCII_NO_NUL",
+	}
+
+	typeNamesR = map[string]TagTypePrimitive{}
+)
+
+// Rational describes an unsigned rational value.
+type Rational struct {
+	// Numerator is the numerator of the rational value.
+	Numerator uint32
+
+	// Denominator is the numerator of the rational value.
+	Denominator uint32
+}
+
+// SignedRational describes a signed rational value.
+type SignedRational struct {
+	// Numerator is the numerator of the rational value.
+	Numerator int32
+
+	// Denominator is the numerator of the rational value.
+	Denominator int32
+}
+
+// Format returns a stringified value for the given encoding. Automatically
+// parses. Automatically calculates count based on type size. This function
+// also supports undefined-type values (the ones that we support, anyway) by
+// way of the String() method that they all require. We can't be more specific
+// because we're a base package and we can't refer to it.
+func FormatFromType(value interface{}, justFirst bool) (phrase string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! Add test
+
+	switch t := value.(type) {
+	case []byte:
+		return DumpBytesToString(t), nil
+	case string:
+		return t, nil
+	case []uint16:
+		if len(t) == 0 {
+			return "", nil
+		}
+
+		if justFirst == true {
+			var valueSuffix string
+			if len(t) > 1 {
+				valueSuffix = "..."
+			}
+
+			return fmt.Sprintf("%v%s", t[0], valueSuffix), nil
+		}
+
+		return fmt.Sprintf("%v", t), nil
+	case []uint32:
+		if len(t) == 0 {
+			return "", nil
+		}
+
+		if justFirst == true {
+			var valueSuffix string
+			if len(t) > 1 {
+				valueSuffix = "..."
+			}
+
+			return fmt.Sprintf("%v%s", t[0], valueSuffix), nil
+		}
+
+		return fmt.Sprintf("%v", t), nil
+	case []Rational:
+		if len(t) == 0 {
+			return "", nil
+		}
+
+		parts := make([]string, len(t))
+		for i, r := range t {
+			parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
+
+			if justFirst == true {
+				break
+			}
+		}
+
+		if justFirst == true {
+			var valueSuffix string
+			if len(t) > 1 {
+				valueSuffix = "..."
+			}
+
+			return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
+		}
+
+		return fmt.Sprintf("%v", parts), nil
+	case []int32:
+		if len(t) == 0 {
+			return "", nil
+		}
+
+		if justFirst == true {
+			var valueSuffix string
+			if len(t) > 1 {
+				valueSuffix = "..."
+			}
+
+			return fmt.Sprintf("%v%s", t[0], valueSuffix), nil
+		}
+
+		return fmt.Sprintf("%v", t), nil
+	case []SignedRational:
+		if len(t) == 0 {
+			return "", nil
+		}
+
+		parts := make([]string, len(t))
+		for i, r := range t {
+			parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
+
+			if justFirst == true {
+				break
+			}
+		}
+
+		if justFirst == true {
+			var valueSuffix string
+			if len(t) > 1 {
+				valueSuffix = "..."
+			}
+
+			return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
+		}
+
+		return fmt.Sprintf("%v", parts), nil
+	case fmt.Stringer:
+		// An undefined value that is documented (or that we otherwise support).
+		return t.String(), nil
+	default:
+		// Affects only "unknown" values, in general.
+		log.Panicf("type can not be formatted into string: %v", reflect.TypeOf(value).Name())
+
+		// Never called.
+		return "", nil
+	}
+}
+
+// Format returns a stringified value for the given encoding. Automatically
+// parses. Automatically calculates count based on type size.
+func FormatFromBytes(rawBytes []byte, tagType TagTypePrimitive, justFirst bool, byteOrder binary.ByteOrder) (phrase string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): !! Add test
+
+	typeSize := tagType.Size()
+
+	if len(rawBytes)%typeSize != 0 {
+		log.Panicf("byte-count (%d) does not align for [%s] type with a size of (%d) bytes", len(rawBytes), TypeNames[tagType], typeSize)
+	}
+
+	// unitCount is the calculated unit-count. This should equal the original
+	// value from the tag (pre-resolution).
+	unitCount := uint32(len(rawBytes) / typeSize)
+
+	// Truncate the items if it's not bytes or a string and we just want the first.
+
+	var value interface{}
+
+	switch tagType {
+	case TypeByte:
+		var err error
+
+		value, err = parser.ParseBytes(rawBytes, unitCount)
+		log.PanicIf(err)
+	case TypeAscii:
+		var err error
+
+		value, err = parser.ParseAscii(rawBytes, unitCount)
+		log.PanicIf(err)
+	case TypeAsciiNoNul:
+		var err error
+
+		value, err = parser.ParseAsciiNoNul(rawBytes, unitCount)
+		log.PanicIf(err)
+	case TypeShort:
+		var err error
+
+		value, err = parser.ParseShorts(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+	case TypeLong:
+		var err error
+
+		value, err = parser.ParseLongs(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+	case TypeRational:
+		var err error
+
+		value, err = parser.ParseRationals(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+	case TypeSignedLong:
+		var err error
+
+		value, err = parser.ParseSignedLongs(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+	case TypeSignedRational:
+		var err error
+
+		value, err = parser.ParseSignedRationals(rawBytes, unitCount, byteOrder)
+		log.PanicIf(err)
+	default:
+		// Affects only "unknown" values, in general.
+		log.Panicf("value of type [%s] can not be formatted into string", tagType.String())
+
+		// Never called.
+		return "", nil
+	}
+
+	phrase, err = FormatFromType(value, justFirst)
+	log.PanicIf(err)
+
+	return phrase, nil
+}
+
+// TranslateStringToType converts user-provided strings to properly-typed
+// values. If a string, returns a string. Else, assumes that it's a single
+// number. If a list needs to be processed, it is the caller's responsibility to
+// split it (according to whichever convention has been established).
+func TranslateStringToType(tagType TagTypePrimitive, valueString string) (value interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if tagType == TypeUndefined {
+		// The caller should just call String() on the decoded type.
+		log.Panicf("undefined-type values are not supported")
+	}
+
+	if tagType == TypeByte {
+		wide, err := strconv.ParseInt(valueString, 16, 8)
+		log.PanicIf(err)
+
+		return byte(wide), nil
+	} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
+		// Whether or not we're putting an NUL on the end is only relevant for
+		// byte-level encoding. This function really just supports a user
+		// interface.
+
+		return valueString, nil
+	} else if tagType == TypeShort {
+		n, err := strconv.ParseUint(valueString, 10, 16)
+		log.PanicIf(err)
+
+		return uint16(n), nil
+	} else if tagType == TypeLong {
+		n, err := strconv.ParseUint(valueString, 10, 32)
+		log.PanicIf(err)
+
+		return uint32(n), nil
+	} else if tagType == TypeRational {
+		parts := strings.SplitN(valueString, "/", 2)
+
+		numerator, err := strconv.ParseUint(parts[0], 10, 32)
+		log.PanicIf(err)
+
+		denominator, err := strconv.ParseUint(parts[1], 10, 32)
+		log.PanicIf(err)
+
+		return Rational{
+			Numerator:   uint32(numerator),
+			Denominator: uint32(denominator),
+		}, nil
+	} else if tagType == TypeSignedLong {
+		n, err := strconv.ParseInt(valueString, 10, 32)
+		log.PanicIf(err)
+
+		return int32(n), nil
+	} else if tagType == TypeSignedRational {
+		parts := strings.SplitN(valueString, "/", 2)
+
+		numerator, err := strconv.ParseInt(parts[0], 10, 32)
+		log.PanicIf(err)
+
+		denominator, err := strconv.ParseInt(parts[1], 10, 32)
+		log.PanicIf(err)
+
+		return SignedRational{
+			Numerator:   int32(numerator),
+			Denominator: int32(denominator),
+		}, nil
+	}
+
+	log.Panicf("from-string encoding for type not supported; this shouldn't happen: [%s]", tagType.String())
+	return nil, nil
+}
+
+// GetTypeByName returns the `TagTypePrimitive` for the given type name.
+// Returns (0) if not valid.
+func GetTypeByName(typeName string) (tagType TagTypePrimitive, found bool) {
+	tagType, found = typeNamesR[typeName]
+	return tagType, found
+}
+
+// BasicTag describes a single tag for any purpose.
+type BasicTag struct {
+	// FqIfdPath is the fully-qualified IFD-path.
+	FqIfdPath string
+
+	// IfdPath is the unindexed IFD-path.
+	IfdPath string
+
+	// TagId is the tag-ID.
+	TagId uint16
+}
+
+func init() {
+	for typeId, typeName := range TypeNames {
+		typeNamesR[typeName] = typeId
+	}
+}

vendor/github.com/dsoprea/go-exif/v2/common/utility.go

@@ -0,0 +1,79 @@
+package exifcommon
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	"github.com/dsoprea/go-logging"
+)
+
+// DumpBytes prints a list of hex-encoded bytes.
+func DumpBytes(data []byte) {
+	fmt.Printf("DUMP: ")
+	for _, x := range data {
+		fmt.Printf("%02x ", x)
+	}
+
+	fmt.Printf("\n")
+}
+
+// DumpBytesClause prints a list like DumpBytes(), but encapsulated in
+// "[]byte { ... }".
+func DumpBytesClause(data []byte) {
+	fmt.Printf("DUMP: ")
+
+	fmt.Printf("[]byte { ")
+
+	for i, x := range data {
+		fmt.Printf("0x%02x", x)
+
+		if i < len(data)-1 {
+			fmt.Printf(", ")
+		}
+	}
+
+	fmt.Printf(" }\n")
+}
+
+// DumpBytesToString returns a stringified list of hex-encoded bytes.
+func DumpBytesToString(data []byte) string {
+	b := new(bytes.Buffer)
+
+	for i, x := range data {
+		_, err := b.WriteString(fmt.Sprintf("%02x", x))
+		log.PanicIf(err)
+
+		if i < len(data)-1 {
+			_, err := b.WriteRune(' ')
+			log.PanicIf(err)
+		}
+	}
+
+	return b.String()
+}
+
+// DumpBytesClauseToString returns a comma-separated list of hex-encoded bytes.
+func DumpBytesClauseToString(data []byte) string {
+	b := new(bytes.Buffer)
+
+	for i, x := range data {
+		_, err := b.WriteString(fmt.Sprintf("0x%02x", x))
+		log.PanicIf(err)
+
+		if i < len(data)-1 {
+			_, err := b.WriteString(", ")
+			log.PanicIf(err)
+		}
+	}
+
+	return b.String()
+}
+
+// ExifFullTimestampString produces a string like "2018:11:30 13:01:49" from a
+// `time.Time` struct. It will attempt to convert to UTC first.
+func ExifFullTimestampString(t time.Time) (fullTimestampPhrase string) {
+	t = t.UTC()
+
+	return fmt.Sprintf("%04d:%02d:%02d %02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
+}

vendor/github.com/dsoprea/go-exif/v2/common/value_context.go

@@ -0,0 +1,412 @@
+package exifcommon
+
+import (
+	"errors"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	parser *Parser
+)
+
+var (
+	// ErrNotFarValue indicates that an offset-based lookup was attempted for a
+	// non-offset-based (embedded) value.
+	ErrNotFarValue = errors.New("not a far value")
+)
+
+// ValueContext embeds all of the parameters required to find and extract the
+// actual tag value.
+type ValueContext struct {
+	unitCount       uint32
+	valueOffset     uint32
+	rawValueOffset  []byte
+	addressableData []byte
+
+	tagType   TagTypePrimitive
+	byteOrder binary.ByteOrder
+
+	// undefinedValueTagType is the effective type to use if this is an
+	// "undefined" value.
+	undefinedValueTagType TagTypePrimitive
+
+	ifdPath string
+	tagId   uint16
+}
+
+// TODO(dustin): We can update newValueContext() to derive `valueOffset` itself (from `rawValueOffset`).
+
+// NewValueContext returns a new ValueContext struct.
+func NewValueContext(ifdPath string, tagId uint16, unitCount, valueOffset uint32, rawValueOffset, addressableData []byte, tagType TagTypePrimitive, byteOrder binary.ByteOrder) *ValueContext {
+	return &ValueContext{
+		unitCount:       unitCount,
+		valueOffset:     valueOffset,
+		rawValueOffset:  rawValueOffset,
+		addressableData: addressableData,
+
+		tagType:   tagType,
+		byteOrder: byteOrder,
+
+		ifdPath: ifdPath,
+		tagId:   tagId,
+	}
+}
+
+// SetUndefinedValueType sets the effective type if this is an unknown-type tag.
+func (vc *ValueContext) SetUndefinedValueType(tagType TagTypePrimitive) {
+	if vc.tagType != TypeUndefined {
+		log.Panicf("can not set effective type for unknown-type tag because this is *not* an unknown-type tag")
+	}
+
+	vc.undefinedValueTagType = tagType
+}
+
+// UnitCount returns the embedded unit-count.
+func (vc *ValueContext) UnitCount() uint32 {
+	return vc.unitCount
+}
+
+// ValueOffset returns the value-offset decoded as a `uint32`.
+func (vc *ValueContext) ValueOffset() uint32 {
+	return vc.valueOffset
+}
+
+// RawValueOffset returns the uninterpreted value-offset. This is used for
+// embedded values (values small enough to fit within the offset bytes rather
+// than needing to be stored elsewhere and referred to by an actual offset).
+func (vc *ValueContext) RawValueOffset() []byte {
+	return vc.rawValueOffset
+}
+
+// AddressableData returns the block of data that we can dereference into.
+func (vc *ValueContext) AddressableData() []byte {
+	return vc.addressableData
+}
+
+// ByteOrder returns the byte-order of numbers.
+func (vc *ValueContext) ByteOrder() binary.ByteOrder {
+	return vc.byteOrder
+}
+
+// IfdPath returns the path of the IFD containing this tag.
+func (vc *ValueContext) IfdPath() string {
+	return vc.ifdPath
+}
+
+// TagId returns the ID of the tag that we represent.
+func (vc *ValueContext) TagId() uint16 {
+	return vc.tagId
+}
+
+// isEmbedded returns whether the value is embedded or a reference. This can't
+// be precalculated since the size is not defined for all types (namely the
+// "undefined" types).
+func (vc *ValueContext) isEmbedded() bool {
+	tagType := vc.effectiveValueType()
+
+	return (tagType.Size() * int(vc.unitCount)) <= 4
+}
+
+// SizeInBytes returns the number of bytes that this value requires. The
+// underlying call will panic if the type is UNDEFINED. It is the
+// responsibility of the caller to preemptively check that.
+func (vc *ValueContext) SizeInBytes() int {
+	tagType := vc.effectiveValueType()
+
+	return tagType.Size() * int(vc.unitCount)
+}
+
+// effectiveValueType returns the effective type of the unknown-type tag or, if
+// not unknown, the actual type.
+func (vc *ValueContext) effectiveValueType() (tagType TagTypePrimitive) {
+	if vc.tagType == TypeUndefined {
+		tagType = vc.undefinedValueTagType
+
+		if tagType == 0 {
+			log.Panicf("undefined-value type not set")
+		}
+	} else {
+		tagType = vc.tagType
+	}
+
+	return tagType
+}
+
+// readRawEncoded returns the encoded bytes for the value that we represent.
+func (vc *ValueContext) readRawEncoded() (rawBytes []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	tagType := vc.effectiveValueType()
+
+	unitSizeRaw := uint32(tagType.Size())
+
+	if vc.isEmbedded() == true {
+		byteLength := unitSizeRaw * vc.unitCount
+		return vc.rawValueOffset[:byteLength], nil
+	}
+
+	return vc.addressableData[vc.valueOffset : vc.valueOffset+vc.unitCount*unitSizeRaw], nil
+}
+
+// GetFarOffset returns the offset if the value is not embedded [within the
+// pointer itself] or an error if an embedded value.
+func (vc *ValueContext) GetFarOffset() (offset uint32, err error) {
+	if vc.isEmbedded() == true {
+		return 0, ErrNotFarValue
+	}
+
+	return vc.valueOffset, nil
+}
+
+// ReadRawEncoded returns the encoded bytes for the value that we represent.
+func (vc *ValueContext) ReadRawEncoded() (rawBytes []byte, err error) {
+
+	// TODO(dustin): Remove this method and rename readRawEncoded in its place.
+
+	return vc.readRawEncoded()
+}
+
+// Format returns a string representation for the value.
+//
+// Where the type is not ASCII, `justFirst` indicates whether to just stringify
+// the first item in the slice (or return an empty string if the slice is
+// empty).
+//
+// Since this method lacks the information to process undefined-type tags (e.g.
+// byte-order, tag-ID, IFD type), it will return an error if attempted. See
+// `Undefined()`.
+func (vc *ValueContext) Format() (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawBytes, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	phrase, err := FormatFromBytes(rawBytes, vc.effectiveValueType(), false, vc.byteOrder)
+	log.PanicIf(err)
+
+	return phrase, nil
+}
+
+// FormatFirst is similar to `Format` but only gets and stringifies the first
+// item.
+func (vc *ValueContext) FormatFirst() (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawBytes, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	phrase, err := FormatFromBytes(rawBytes, vc.tagType, true, vc.byteOrder)
+	log.PanicIf(err)
+
+	return phrase, nil
+}
+
+// ReadBytes parses the encoded byte-array from the value-context.
+func (vc *ValueContext) ReadBytes() (value []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseBytes(rawValue, vc.unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadAscii parses the encoded NUL-terminated ASCII string from the value-
+// context.
+func (vc *ValueContext) ReadAscii() (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseAscii(rawValue, vc.unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadAsciiNoNul parses the non-NUL-terminated encoded ASCII string from the
+// value-context.
+func (vc *ValueContext) ReadAsciiNoNul() (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseAsciiNoNul(rawValue, vc.unitCount)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadShorts parses the list of encoded shorts from the value-context.
+func (vc *ValueContext) ReadShorts() (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseShorts(rawValue, vc.unitCount, vc.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadLongs parses the list of encoded, unsigned longs from the value-context.
+func (vc *ValueContext) ReadLongs() (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseLongs(rawValue, vc.unitCount, vc.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadRationals parses the list of encoded, unsigned rationals from the value-
+// context.
+func (vc *ValueContext) ReadRationals() (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseRationals(rawValue, vc.unitCount, vc.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadSignedLongs parses the list of encoded, signed longs from the value-context.
+func (vc *ValueContext) ReadSignedLongs() (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseSignedLongs(rawValue, vc.unitCount, vc.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// ReadSignedRationals parses the list of encoded, signed rationals from the
+// value-context.
+func (vc *ValueContext) ReadSignedRationals() (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	rawValue, err := vc.readRawEncoded()
+	log.PanicIf(err)
+
+	value, err = parser.ParseSignedRationals(rawValue, vc.unitCount, vc.byteOrder)
+	log.PanicIf(err)
+
+	return value, nil
+}
+
+// Values knows how to resolve the given value. This value is always a list
+// (undefined-values aside), so we're named accordingly.
+//
+// Since this method lacks the information to process unknown-type tags (e.g.
+// byte-order, tag-ID, IFD type), it will return an error if attempted. See
+// `Undefined()`.
+func (vc *ValueContext) Values() (values interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	if vc.tagType == TypeByte {
+		values, err = vc.ReadBytes()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeAscii {
+		values, err = vc.ReadAscii()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeAsciiNoNul {
+		values, err = vc.ReadAsciiNoNul()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeShort {
+		values, err = vc.ReadShorts()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeLong {
+		values, err = vc.ReadLongs()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeRational {
+		values, err = vc.ReadRationals()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeSignedLong {
+		values, err = vc.ReadSignedLongs()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeSignedRational {
+		values, err = vc.ReadSignedRationals()
+		log.PanicIf(err)
+	} else if vc.tagType == TypeUndefined {
+		log.Panicf("will not parse undefined-type value")
+
+		// Never called.
+		return nil, nil
+	} else {
+		log.Panicf("value of type [%s] is unparseable", vc.tagType)
+		// Never called.
+		return nil, nil
+	}
+
+	return values, nil
+}
+
+func init() {
+	parser = new(Parser)
+}

vendor/github.com/dsoprea/go-exif/v2/common/value_encoder.go

@@ -0,0 +1,229 @@
+package exifcommon
+
+import (
+	"bytes"
+	"reflect"
+	"time"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	typeEncodeLogger = log.NewLogger("exif.type_encode")
+)
+
+// EncodedData encapsulates the compound output of an encoding operation.
+type EncodedData struct {
+	Type    TagTypePrimitive
+	Encoded []byte
+
+	// TODO(dustin): Is this really necessary? We might have this just to correlate to the incoming stream format (raw bytes and a unit-count both for incoming and outgoing).
+	UnitCount uint32
+}
+
+// ValueEncoder knows how to encode values of every type to bytes.
+type ValueEncoder struct {
+	byteOrder binary.ByteOrder
+}
+
+// NewValueEncoder returns a new ValueEncoder.
+func NewValueEncoder(byteOrder binary.ByteOrder) *ValueEncoder {
+	return &ValueEncoder{
+		byteOrder: byteOrder,
+	}
+}
+
+func (ve *ValueEncoder) encodeBytes(value []uint8) (ed EncodedData, err error) {
+	ed.Type = TypeByte
+	ed.Encoded = []byte(value)
+	ed.UnitCount = uint32(len(value))
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeAscii(value string) (ed EncodedData, err error) {
+	ed.Type = TypeAscii
+
+	ed.Encoded = []byte(value)
+	ed.Encoded = append(ed.Encoded, 0)
+
+	ed.UnitCount = uint32(len(ed.Encoded))
+
+	return ed, nil
+}
+
+// encodeAsciiNoNul returns a string encoded as a byte-string without a trailing
+// NUL byte.
+//
+// Note that:
+//
+// 1. This type can not be automatically encoded using `Encode()`. The default
+//    mode is to encode *with* a trailing NUL byte using `encodeAscii`. Only
+//    certain undefined-type tags using an unterminated ASCII string and these
+//    are exceptional in nature.
+//
+// 2. The presence of this method allows us to completely test the complimentary
+//    no-nul parser.
+//
+func (ve *ValueEncoder) encodeAsciiNoNul(value string) (ed EncodedData, err error) {
+	ed.Type = TypeAsciiNoNul
+	ed.Encoded = []byte(value)
+	ed.UnitCount = uint32(len(ed.Encoded))
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeShorts(value []uint16) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*2)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint16(ed.Encoded[i*2:(i+1)*2], value[i])
+	}
+
+	ed.Type = TypeShort
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeLongs(value []uint32) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*4)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint32(ed.Encoded[i*4:(i+1)*4], value[i])
+	}
+
+	ed.Type = TypeLong
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeRationals(value []Rational) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+	ed.Encoded = make([]byte, ed.UnitCount*8)
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		ve.byteOrder.PutUint32(ed.Encoded[i*8+0:i*8+4], value[i].Numerator)
+		ve.byteOrder.PutUint32(ed.Encoded[i*8+4:i*8+8], value[i].Denominator)
+	}
+
+	ed.Type = TypeRational
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeSignedLongs(value []int32) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+
+	b := bytes.NewBuffer(make([]byte, 0, 8*ed.UnitCount))
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		err := binary.Write(b, ve.byteOrder, value[i])
+		log.PanicIf(err)
+	}
+
+	ed.Type = TypeSignedLong
+	ed.Encoded = b.Bytes()
+
+	return ed, nil
+}
+
+func (ve *ValueEncoder) encodeSignedRationals(value []SignedRational) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	ed.UnitCount = uint32(len(value))
+
+	b := bytes.NewBuffer(make([]byte, 0, 8*ed.UnitCount))
+
+	for i := uint32(0); i < ed.UnitCount; i++ {
+		err := binary.Write(b, ve.byteOrder, value[i].Numerator)
+		log.PanicIf(err)
+
+		err = binary.Write(b, ve.byteOrder, value[i].Denominator)
+		log.PanicIf(err)
+	}
+
+	ed.Type = TypeSignedRational
+	ed.Encoded = b.Bytes()
+
+	return ed, nil
+}
+
+// Encode returns bytes for the given value, infering type from the actual
+// value. This does not support `TypeAsciiNoNull` (all strings are encoded as
+// `TypeAscii`).
+func (ve *ValueEncoder) Encode(value interface{}) (ed EncodedData, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	switch value.(type) {
+	case []byte:
+		ed, err = ve.encodeBytes(value.([]byte))
+		log.PanicIf(err)
+	case string:
+		ed, err = ve.encodeAscii(value.(string))
+		log.PanicIf(err)
+	case []uint16:
+		ed, err = ve.encodeShorts(value.([]uint16))
+		log.PanicIf(err)
+	case []uint32:
+		ed, err = ve.encodeLongs(value.([]uint32))
+		log.PanicIf(err)
+	case []Rational:
+		ed, err = ve.encodeRationals(value.([]Rational))
+		log.PanicIf(err)
+	case []int32:
+		ed, err = ve.encodeSignedLongs(value.([]int32))
+		log.PanicIf(err)
+	case []SignedRational:
+		ed, err = ve.encodeSignedRationals(value.([]SignedRational))
+		log.PanicIf(err)
+	case time.Time:
+		// For convenience, if the user doesn't want to deal with translation
+		// semantics with timestamps.
+
+		t := value.(time.Time)
+		s := ExifFullTimestampString(t)
+
+		ed, err = ve.encodeAscii(s)
+		log.PanicIf(err)
+	default:
+		log.Panicf("value not encodable: [%s] [%v]", reflect.TypeOf(value), value)
+	}
+
+	return ed, nil
+}

vendor/github.com/dsoprea/go-exif/v2/error.go

@@ -0,0 +1,14 @@
+package exif
+
+import (
+	"errors"
+)
+
+var (
+	// ErrTagNotFound indicates that the tag was not found.
+	ErrTagNotFound = errors.New("tag not found")
+
+	// ErrTagNotKnown indicates that the tag is not registered with us as a
+	// known tag.
+	ErrTagNotKnown = errors.New("tag is not known")
+)

vendor/github.com/dsoprea/go-exif/v2/exif.go

@@ -0,0 +1,258 @@
+package exif
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+
+	"encoding/binary"
+	"io/ioutil"
+
+	"github.com/dsoprea/go-logging"
+
+	"github.com/dsoprea/go-exif/v2/common"
+)
+
+const (
+	// ExifAddressableAreaStart is the absolute offset in the file that all
+	// offsets are relative to.
+	ExifAddressableAreaStart = uint32(0x0)
+
+	// ExifDefaultFirstIfdOffset is essentially the number of bytes in addition
+	// to `ExifAddressableAreaStart` that you have to move in order to escape
+	// the rest of the header and get to the earliest point where we can put
+	// stuff (which has to be the first IFD). This is the size of the header
+	// sequence containing the two-character byte-order, two-character fixed-
+	// bytes, and the four bytes describing the first-IFD offset.
+	ExifDefaultFirstIfdOffset = uint32(2 + 2 + 4)
+)
+
+const (
+	// ExifSignatureLength is the number of bytes in the EXIF signature (which
+	// customarily includes the first IFD offset).
+	ExifSignatureLength = 8
+)
+
+var (
+	exifLogger = log.NewLogger("exif.exif")
+
+	ExifBigEndianSignature    = [4]byte{'M', 'M', 0x00, 0x2a}
+	ExifLittleEndianSignature = [4]byte{'I', 'I', 0x2a, 0x00}
+)
+
+var (
+	ErrNoExif          = errors.New("no exif data")
+	ErrExifHeaderError = errors.New("exif header error")
+)
+
+// SearchAndExtractExif searches for an EXIF blob in the byte-slice.
+func SearchAndExtractExif(data []byte) (rawExif []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	b := bytes.NewBuffer(data)
+
+	rawExif, err = SearchAndExtractExifWithReader(b)
+	if err != nil {
+		if err == ErrNoExif {
+			return nil, err
+		}
+
+		log.Panic(err)
+	}
+
+	return rawExif, nil
+}
+
+// SearchAndExtractExifWithReader searches for an EXIF blob using an
+// `io.Reader`. We can't know how much long the EXIF data is without parsing it,
+// so this will likely grab up a lot of the image-data, too.
+func SearchAndExtractExifWithReader(r io.Reader) (rawExif []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Search for the beginning of the EXIF information. The EXIF is near the
+	// beginning of most JPEGs, so this likely doesn't have a high cost (at
+	// least, again, with JPEGs).
+
+	br := bufio.NewReader(r)
+	discarded := 0
+
+	for {
+		window, err := br.Peek(ExifSignatureLength)
+		if err != nil {
+			if err == io.EOF {
+				return nil, ErrNoExif
+			}
+
+			log.Panic(err)
+		}
+
+		_, err = ParseExifHeader(window)
+		if err != nil {
+			if log.Is(err, ErrNoExif) == true {
+				// No EXIF. Move forward by one byte.
+
+				_, err := br.Discard(1)
+				log.PanicIf(err)
+
+				discarded++
+
+				continue
+			}
+
+			// Some other error.
+			log.Panic(err)
+		}
+
+		break
+	}
+
+	exifLogger.Debugf(nil, "Found EXIF blob (%d) bytes from initial position.", discarded)
+
+	rawExif, err = ioutil.ReadAll(br)
+	log.PanicIf(err)
+
+	return rawExif, nil
+}
+
+// SearchFileAndExtractExif returns a slice from the beginning of the EXIF data
+// to the end of the file (it's not practical to try and calculate where the
+// data actually ends).
+func SearchFileAndExtractExif(filepath string) (rawExif []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Open the file.
+
+	f, err := os.Open(filepath)
+	log.PanicIf(err)
+
+	defer f.Close()
+
+	rawExif, err = SearchAndExtractExifWithReader(f)
+	log.PanicIf(err)
+
+	return rawExif, nil
+}
+
+type ExifHeader struct {
+	ByteOrder      binary.ByteOrder
+	FirstIfdOffset uint32
+}
+
+func (eh ExifHeader) String() string {
+	return fmt.Sprintf("ExifHeader<BYTE-ORDER=[%v] FIRST-IFD-OFFSET=(0x%02x)>", eh.ByteOrder, eh.FirstIfdOffset)
+}
+
+// ParseExifHeader parses the bytes at the very top of the header.
+//
+// This will panic with ErrNoExif on any data errors so that we can double as
+// an EXIF-detection routine.
+func ParseExifHeader(data []byte) (eh ExifHeader, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// Good reference:
+	//
+	//      CIPA DC-008-2016; JEITA CP-3451D
+	//      -> http://www.cipa.jp/std/documents/e/DC-008-Translation-2016-E.pdf
+
+	if len(data) < ExifSignatureLength {
+		exifLogger.Warningf(nil, "Not enough data for EXIF header: (%d)", len(data))
+		return eh, ErrNoExif
+	}
+
+	if bytes.Equal(data[:4], ExifBigEndianSignature[:]) == true {
+		eh.ByteOrder = binary.BigEndian
+	} else if bytes.Equal(data[:4], ExifLittleEndianSignature[:]) == true {
+		eh.ByteOrder = binary.LittleEndian
+	} else {
+		return eh, ErrNoExif
+	}
+
+	eh.FirstIfdOffset = eh.ByteOrder.Uint32(data[4:8])
+
+	return eh, nil
+}
+
+// Visit recursively invokes a callback for every tag.
+func Visit(rootIfdIdentity *exifcommon.IfdIdentity, ifdMapping *exifcommon.IfdMapping, tagIndex *TagIndex, exifData []byte, visitor TagVisitorFn) (eh ExifHeader, furthestOffset uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	eh, err = ParseExifHeader(exifData)
+	log.PanicIf(err)
+
+	ie := NewIfdEnumerate(ifdMapping, tagIndex, exifData, eh.ByteOrder)
+
+	_, err = ie.Scan(rootIfdIdentity, eh.FirstIfdOffset, visitor)
+	log.PanicIf(err)
+
+	furthestOffset = ie.FurthestOffset()
+
+	return eh, furthestOffset, nil
+}
+
+// Collect recursively builds a static structure of all IFDs and tags.
+func Collect(ifdMapping *exifcommon.IfdMapping, tagIndex *TagIndex, exifData []byte) (eh ExifHeader, index IfdIndex, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	eh, err = ParseExifHeader(exifData)
+	log.PanicIf(err)
+
+	ie := NewIfdEnumerate(ifdMapping, tagIndex, exifData, eh.ByteOrder)
+
+	index, err = ie.Collect(eh.FirstIfdOffset)
+	log.PanicIf(err)
+
+	return eh, index, nil
+}
+
+// BuildExifHeader constructs the bytes that go at the front of the stream.
+func BuildExifHeader(byteOrder binary.ByteOrder, firstIfdOffset uint32) (headerBytes []byte, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	b := new(bytes.Buffer)
+
+	var signatureBytes []byte
+	if byteOrder == binary.BigEndian {
+		signatureBytes = ExifBigEndianSignature[:]
+	} else {
+		signatureBytes = ExifLittleEndianSignature[:]
+	}
+
+	_, err = b.Write(signatureBytes)
+	log.PanicIf(err)
+
+	err = binary.Write(b, byteOrder, firstIfdOffset)
+	log.PanicIf(err)
+
+	return b.Bytes(), nil
+}

vendor/github.com/dsoprea/go-exif/v2/go.mod

@@ -0,0 +1,15 @@
+module github.com/dsoprea/go-exif/v2
+
+go 1.13
+
+// Development only
+// replace github.com/dsoprea/go-logging => ../../go-logging
+
+require (
+	github.com/dsoprea/go-logging v0.0.0-20200517223158-a10564966e9d
+	github.com/dsoprea/go-utility v0.0.0-20200711062821-fab8125e9bdf // indirect
+	github.com/golang/geo v0.0.0-20200319012246-673a6f80352d
+	github.com/jessevdk/go-flags v1.4.0
+	golang.org/x/net v0.0.0-20200513185701-a91f0712d120 // indirect
+	gopkg.in/yaml.v2 v2.3.0
+)