[bugfix] Close reader gracefully when streaming recache of remote media to fileserver api caller (#1281)

* close pipereader on failed data function

* gently slurp the bytes

* readability updates

* go fmt

* tidy up file server tests + add more cases

* start moving io wrappers to separate iotools package. Remove use of buffering while piping recache stream

Signed-off-by: kim <grufwub@gmail.com>

* add license text

Signed-off-by: kim <grufwub@gmail.com>
Co-authored-by: kim <grufwub@gmail.com>

internal/api/client/fileserver/fileserver_test.go

@@ -0,0 +1,109 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero 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 Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package fileserver_test
+
+import (
+	"context"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/api/client/fileserver"
+	"github.com/superseriousbusiness/gotosocial/internal/concurrency"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/email"
+	"github.com/superseriousbusiness/gotosocial/internal/federation"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/media"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/internal/processing"
+	"github.com/superseriousbusiness/gotosocial/internal/storage"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+	"github.com/superseriousbusiness/gotosocial/testrig"
+)
+
+type FileserverTestSuite struct {
+	// standard suite interfaces
+	suite.Suite
+	db           db.DB
+	storage      *storage.Driver
+	federator    federation.Federator
+	tc           typeutils.TypeConverter
+	processor    processing.Processor
+	mediaManager media.Manager
+	oauthServer  oauth.Server
+	emailSender  email.Sender
+
+	// standard suite models
+	testTokens       map[string]*gtsmodel.Token
+	testClients      map[string]*gtsmodel.Client
+	testApplications map[string]*gtsmodel.Application
+	testUsers        map[string]*gtsmodel.User
+	testAccounts     map[string]*gtsmodel.Account
+	testAttachments  map[string]*gtsmodel.MediaAttachment
+
+	// item being tested
+	fileServer *fileserver.FileServer
+}
+
+/*
+	TEST INFRASTRUCTURE
+*/
+
+func (suite *FileserverTestSuite) SetupSuite() {
+	testrig.InitTestConfig()
+	testrig.InitTestLog()
+
+	fedWorker := concurrency.NewWorkerPool[messages.FromFederator](-1, -1)
+	clientWorker := concurrency.NewWorkerPool[messages.FromClientAPI](-1, -1)
+
+	suite.db = testrig.NewTestDB()
+	suite.storage = testrig.NewInMemoryStorage()
+	suite.federator = testrig.NewTestFederator(suite.db, testrig.NewTestTransportController(testrig.NewMockHTTPClient(nil, "../../../../testrig/media"), suite.db, fedWorker), suite.storage, suite.mediaManager, fedWorker)
+	suite.emailSender = testrig.NewEmailSender("../../../../web/template/", nil)
+
+	suite.processor = testrig.NewTestProcessor(suite.db, suite.storage, suite.federator, suite.emailSender, testrig.NewTestMediaManager(suite.db, suite.storage), clientWorker, fedWorker)
+	suite.tc = testrig.NewTestTypeConverter(suite.db)
+	suite.mediaManager = testrig.NewTestMediaManager(suite.db, suite.storage)
+	suite.oauthServer = testrig.NewTestOauthServer(suite.db)
+
+	suite.fileServer = fileserver.New(suite.processor).(*fileserver.FileServer)
+}
+
+func (suite *FileserverTestSuite) SetupTest() {
+	testrig.StandardDBSetup(suite.db, nil)
+	testrig.StandardStorageSetup(suite.storage, "../../../../testrig/media")
+	suite.testTokens = testrig.NewTestTokens()
+	suite.testClients = testrig.NewTestClients()
+	suite.testApplications = testrig.NewTestApplications()
+	suite.testUsers = testrig.NewTestUsers()
+	suite.testAccounts = testrig.NewTestAccounts()
+	suite.testAttachments = testrig.NewTestAttachments()
+}
+
+func (suite *FileserverTestSuite) TearDownSuite() {
+	if err := suite.db.Stop(context.Background()); err != nil {
+		log.Panicf("error closing db connection: %s", err)
+	}
+}
+
+func (suite *FileserverTestSuite) TearDownTest() {
+	testrig.StandardDBTeardown(suite.db)
+	testrig.StandardStorageTeardown(suite.storage)
+}

internal/api/client/fileserver/servefile.go

@@ -19,7 +19,9 @@
 package fileserver
 
 import (
+	"bytes"
 	"fmt"
+	"io"
 	"net/http"
 	"strconv"
 
@@ -120,5 +122,14 @@ func (m *FileServer) ServeFile(c *gin.Context) {
 		return
 	}
 
-	c.DataFromReader(http.StatusOK, content.ContentLength, format, content.Content, nil)
+	// try to slurp the first few bytes to make sure we have something
+	b := bytes.NewBuffer(make([]byte, 0, 64))
+	if _, err := io.CopyN(b, content.Content, 64); err != nil {
+		err = fmt.Errorf("ServeFile: error reading from content: %w", err)
+		api.ErrorHandler(c, gtserror.NewErrorNotFound(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	// we're good, return the slurped bytes + the rest of the content
+	c.DataFromReader(http.StatusOK, content.ContentLength, format, io.MultiReader(b, content.Content), nil)
 }

internal/api/client/fileserver/servefile_test.go

@@ -20,196 +20,251 @@ package fileserver_test
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
-	"github.com/gin-gonic/gin"
 	"github.com/stretchr/testify/suite"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/fileserver"
-	"github.com/superseriousbusiness/gotosocial/internal/concurrency"
-	"github.com/superseriousbusiness/gotosocial/internal/db"
-	"github.com/superseriousbusiness/gotosocial/internal/email"
-	"github.com/superseriousbusiness/gotosocial/internal/federation"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
-	"github.com/superseriousbusiness/gotosocial/internal/log"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
-	"github.com/superseriousbusiness/gotosocial/internal/messages"
-	"github.com/superseriousbusiness/gotosocial/internal/oauth"
-	"github.com/superseriousbusiness/gotosocial/internal/processing"
-	"github.com/superseriousbusiness/gotosocial/internal/storage"
-	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
 	"github.com/superseriousbusiness/gotosocial/testrig"
 )
 
 type ServeFileTestSuite struct {
-	// standard suite interfaces
+	FileserverTestSuite
-	suite.Suite
-	db           db.DB
-	storage      *storage.Driver
-	federator    federation.Federator
-	tc           typeutils.TypeConverter
-	processor    processing.Processor
-	mediaManager media.Manager
-	oauthServer  oauth.Server
-	emailSender  email.Sender
-
-	// standard suite models
-	testTokens       map[string]*gtsmodel.Token
-	testClients      map[string]*gtsmodel.Client
-	testApplications map[string]*gtsmodel.Application
-	testUsers        map[string]*gtsmodel.User
-	testAccounts     map[string]*gtsmodel.Account
-	testAttachments  map[string]*gtsmodel.MediaAttachment
-
-	// item being tested
-	fileServer *fileserver.FileServer
 }
 
-/*
+// GetFile is just a convenience function to save repetition in this test suite.
-	TEST INFRASTRUCTURE
+// It takes the required params to serve a file, calls the handler, and returns
-*/
+// the http status code, the response headers, and the parsed body bytes.
-
+func (suite *ServeFileTestSuite) GetFile(
-func (suite *ServeFileTestSuite) SetupSuite() {
+	accountID string,
-	// setup standard items
+	mediaType media.Type,
-	testrig.InitTestConfig()
+	mediaSize media.Size,
-	testrig.InitTestLog()
+	filename string,
-
+) (code int, headers http.Header, body []byte) {
-	fedWorker := concurrency.NewWorkerPool[messages.FromFederator](-1, -1)
-	clientWorker := concurrency.NewWorkerPool[messages.FromClientAPI](-1, -1)
-
-	suite.db = testrig.NewTestDB()
-	suite.storage = testrig.NewInMemoryStorage()
-	suite.federator = testrig.NewTestFederator(suite.db, testrig.NewTestTransportController(testrig.NewMockHTTPClient(nil, "../../../../testrig/media"), suite.db, fedWorker), suite.storage, suite.mediaManager, fedWorker)
-	suite.emailSender = testrig.NewEmailSender("../../../../web/template/", nil)
-
-	suite.processor = testrig.NewTestProcessor(suite.db, suite.storage, suite.federator, suite.emailSender, testrig.NewTestMediaManager(suite.db, suite.storage), clientWorker, fedWorker)
-	suite.tc = testrig.NewTestTypeConverter(suite.db)
-	suite.mediaManager = testrig.NewTestMediaManager(suite.db, suite.storage)
-	suite.oauthServer = testrig.NewTestOauthServer(suite.db)
-
-	// setup module being tested
-	suite.fileServer = fileserver.New(suite.processor).(*fileserver.FileServer)
-}
-
-func (suite *ServeFileTestSuite) TearDownSuite() {
-	if err := suite.db.Stop(context.Background()); err != nil {
-		log.Panicf("error closing db connection: %s", err)
-	}
-}
-
-func (suite *ServeFileTestSuite) SetupTest() {
-	testrig.StandardDBSetup(suite.db, nil)
-	testrig.StandardStorageSetup(suite.storage, "../../../../testrig/media")
-	suite.testTokens = testrig.NewTestTokens()
-	suite.testClients = testrig.NewTestClients()
-	suite.testApplications = testrig.NewTestApplications()
-	suite.testUsers = testrig.NewTestUsers()
-	suite.testAccounts = testrig.NewTestAccounts()
-	suite.testAttachments = testrig.NewTestAttachments()
-}
-
-func (suite *ServeFileTestSuite) TearDownTest() {
-	testrig.StandardDBTeardown(suite.db)
-	testrig.StandardStorageTeardown(suite.storage)
-}
-
-/*
-	ACTUAL TESTS
-*/
-
-func (suite *ServeFileTestSuite) TestServeOriginalFileSuccessful() {
-	targetAttachment, ok := suite.testAttachments["admin_account_status_1_attachment_1"]
-	suite.True(ok)
-	suite.NotNil(targetAttachment)
-
 	recorder := httptest.NewRecorder()
-	ctx, _ := testrig.CreateGinTestContext(recorder, nil)
-	ctx.Request = httptest.NewRequest(http.MethodGet, targetAttachment.URL, nil)
-	ctx.Request.Header.Set("accept", "*/*")
 
-	// normally the router would populate these params from the path values,
+	ctx, _ := testrig.CreateGinTestContext(recorder, nil)
-	// but because we're calling the ServeFile function directly, we need to set them manually.
+	ctx.Request = httptest.NewRequest(http.MethodGet, "http://localhost:8080/whatever", nil)
-	ctx.Params = gin.Params{
+	ctx.Request.Header.Set("accept", "*/*")
-		gin.Param{
+	ctx.AddParam(fileserver.AccountIDKey, accountID)
-			Key:   fileserver.AccountIDKey,
+	ctx.AddParam(fileserver.MediaTypeKey, string(mediaType))
-			Value: targetAttachment.AccountID,
+	ctx.AddParam(fileserver.MediaSizeKey, string(mediaSize))
-		},
+	ctx.AddParam(fileserver.FileNameKey, filename)
-		gin.Param{
+
-			Key:   fileserver.MediaTypeKey,
+	suite.fileServer.ServeFile(ctx)
-			Value: string(media.TypeAttachment),
+	code = recorder.Code
-		},
+	headers = recorder.Result().Header
-		gin.Param{
+
-			Key:   fileserver.MediaSizeKey,
+	var err error
-			Value: string(media.SizeOriginal),
+	body, err = ioutil.ReadAll(recorder.Body)
-		},
+	if err != nil {
-		gin.Param{
+		suite.FailNow(err.Error())
-			Key:   fileserver.FileNameKey,
-			Value: fmt.Sprintf("%s.jpeg", targetAttachment.ID),
-		},
 	}
 
-	// call the function we're testing and check status code
+	return
-	suite.fileServer.ServeFile(ctx)
-	suite.EqualValues(http.StatusOK, recorder.Code)
-	suite.EqualValues("image/jpeg", recorder.Header().Get("content-type"))
-
-	b, err := ioutil.ReadAll(recorder.Body)
-	suite.NoError(err)
-	suite.NotNil(b)
-
-	fileInStorage, err := suite.storage.Get(ctx, targetAttachment.File.Path)
-	suite.NoError(err)
-	suite.NotNil(fileInStorage)
-	suite.Equal(b, fileInStorage)
 }
 
-func (suite *ServeFileTestSuite) TestServeSmallFileSuccessful() {
+// UncacheAttachment is a convenience function that uncaches the targetAttachment by
-	targetAttachment, ok := suite.testAttachments["admin_account_status_1_attachment_1"]
+// removing its associated files from storage, and updating the database.
-	suite.True(ok)
+func (suite *ServeFileTestSuite) UncacheAttachment(targetAttachment *gtsmodel.MediaAttachment) {
-	suite.NotNil(targetAttachment)
+	ctx := context.Background()
 
-	recorder := httptest.NewRecorder()
+	cached := false
-	ctx, _ := testrig.CreateGinTestContext(recorder, nil)
+	targetAttachment.Cached = &cached
-	ctx.Request = httptest.NewRequest(http.MethodGet, targetAttachment.Thumbnail.URL, nil)
-	ctx.Request.Header.Set("accept", "*/*")
 
-	// normally the router would populate these params from the path values,
+	if err := suite.db.UpdateByID(ctx, targetAttachment, targetAttachment.ID, "cached"); err != nil {
-	// but because we're calling the ServeFile function directly, we need to set them manually.
+		suite.FailNow(err.Error())
-	ctx.Params = gin.Params{
+	}
-		gin.Param{
+	if err := suite.storage.Delete(ctx, targetAttachment.File.Path); err != nil {
-			Key:   fileserver.AccountIDKey,
+		suite.FailNow(err.Error())
-			Value: targetAttachment.AccountID,
+	}
-		},
+	if err := suite.storage.Delete(ctx, targetAttachment.Thumbnail.Path); err != nil {
-		gin.Param{
+		suite.FailNow(err.Error())
-			Key:   fileserver.MediaTypeKey,
+	}
-			Value: string(media.TypeAttachment),
+}
-		},
+
-		gin.Param{
+func (suite *ServeFileTestSuite) TestServeOriginalLocalFileOK() {
-			Key:   fileserver.MediaSizeKey,
+	targetAttachment := &gtsmodel.MediaAttachment{}
-			Value: string(media.SizeSmall),
+	*targetAttachment = *suite.testAttachments["admin_account_status_1_attachment_1"]
-		},
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.File.Path)
-		gin.Param{
+	if err != nil {
-			Key:   fileserver.FileNameKey,
+		suite.FailNow(err.Error())
-			Value: fmt.Sprintf("%s.jpeg", targetAttachment.ID),
-		},
 	}
 
-	// call the function we're testing and check status code
+	code, headers, body := suite.GetFile(
-	suite.fileServer.ServeFile(ctx)
+		targetAttachment.AccountID,
-	suite.EqualValues(http.StatusOK, recorder.Code)
+		media.TypeAttachment,
-	suite.EqualValues("image/jpeg", recorder.Header().Get("content-type"))
+		media.SizeOriginal,
+		targetAttachment.ID+".jpeg",
+	)
 
-	b, err := ioutil.ReadAll(recorder.Body)
+	suite.Equal(http.StatusOK, code)
-	suite.NoError(err)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
-	suite.NotNil(b)
+	suite.Equal(fileInStorage, body)
+}
 
-	fileInStorage, err := suite.storage.Get(ctx, targetAttachment.Thumbnail.Path)
+func (suite *ServeFileTestSuite) TestServeSmallLocalFileOK() {
-	suite.NoError(err)
+	targetAttachment := &gtsmodel.MediaAttachment{}
-	suite.NotNil(fileInStorage)
+	*targetAttachment = *suite.testAttachments["admin_account_status_1_attachment_1"]
-	suite.Equal(b, fileInStorage)
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.Thumbnail.Path)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	code, headers, body := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeSmall,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusOK, code)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
+	suite.Equal(fileInStorage, body)
+}
+
+func (suite *ServeFileTestSuite) TestServeOriginalRemoteFileOK() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.File.Path)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	code, headers, body := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeOriginal,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusOK, code)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
+	suite.Equal(fileInStorage, body)
+}
+
+func (suite *ServeFileTestSuite) TestServeSmallRemoteFileOK() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.Thumbnail.Path)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	code, headers, body := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeSmall,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusOK, code)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
+	suite.Equal(fileInStorage, body)
+}
+
+func (suite *ServeFileTestSuite) TestServeOriginalRemoteFileRecache() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.File.Path)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	// uncache the attachment so we'll have to refetch it from the 'remote' instance
+	suite.UncacheAttachment(targetAttachment)
+
+	code, headers, body := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeOriginal,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusOK, code)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
+	suite.Equal(fileInStorage, body)
+}
+
+func (suite *ServeFileTestSuite) TestServeSmallRemoteFileRecache() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+	fileInStorage, err := suite.storage.Get(context.Background(), targetAttachment.Thumbnail.Path)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	// uncache the attachment so we'll have to refetch it from the 'remote' instance
+	suite.UncacheAttachment(targetAttachment)
+
+	code, headers, body := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeSmall,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusOK, code)
+	suite.Equal("image/jpeg", headers.Get("content-type"))
+	suite.Equal(fileInStorage, body)
+}
+
+func (suite *ServeFileTestSuite) TestServeOriginalRemoteFileRecacheNotFound() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+
+	// uncache the attachment *and* set the remote URL to something that will return a 404
+	suite.UncacheAttachment(targetAttachment)
+	targetAttachment.RemoteURL = "http://nothing.at.this.url/weeeeeeeee"
+	if err := suite.db.UpdateByID(context.Background(), targetAttachment, targetAttachment.ID, "remote_url"); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	code, _, _ := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeOriginal,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusNotFound, code)
+}
+
+func (suite *ServeFileTestSuite) TestServeSmallRemoteFileRecacheNotFound() {
+	targetAttachment := &gtsmodel.MediaAttachment{}
+	*targetAttachment = *suite.testAttachments["remote_account_1_status_1_attachment_1"]
+
+	// uncache the attachment *and* set the remote URL to something that will return a 404
+	suite.UncacheAttachment(targetAttachment)
+	targetAttachment.RemoteURL = "http://nothing.at.this.url/weeeeeeeee"
+	if err := suite.db.UpdateByID(context.Background(), targetAttachment, targetAttachment.ID, "remote_url"); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	code, _, _ := suite.GetFile(
+		targetAttachment.AccountID,
+		media.TypeAttachment,
+		media.SizeSmall,
+		targetAttachment.ID+".jpeg",
+	)
+
+	suite.Equal(http.StatusNotFound, code)
+}
+
+// Callers trying to get some random-ass file that doesn't exist should just get a 404
+func (suite *ServeFileTestSuite) TestServeFileNotFound() {
+	code, _, _ := suite.GetFile(
+		"01GMMY4G9B0QEG0PQK5Q5JGJWZ",
+		media.TypeAttachment,
+		media.SizeOriginal,
+		"01GMMY68Y7E5DJ3CA3Y9SS8524.jpeg",
+	)
+
+	suite.Equal(http.StatusNotFound, code)
 }
 
 func TestServeFileTestSuite(t *testing.T) {

internal/iotools/io.go

@@ -0,0 +1,121 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero 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 Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package iotools
+
+import (
+	"io"
+)
+
+// ReadFnCloser takes an io.Reader and wraps it to use the provided function to implement io.Closer.
+func ReadFnCloser(r io.Reader, close func() error) io.ReadCloser {
+	return &readFnCloser{
+		Reader: r,
+		close:  close,
+	}
+}
+
+type readFnCloser struct {
+	io.Reader
+	close func() error
+}
+
+func (r *readFnCloser) Close() error {
+	return r.close()
+}
+
+// WriteFnCloser takes an io.Writer and wraps it to use the provided function to implement io.Closer.
+func WriteFnCloser(w io.Writer, close func() error) io.WriteCloser {
+	return &writeFnCloser{
+		Writer: w,
+		close:  close,
+	}
+}
+
+type writeFnCloser struct {
+	io.Writer
+	close func() error
+}
+
+func (r *writeFnCloser) Close() error {
+	return r.close()
+}
+
+// SilentReader wraps an io.Reader to silence any
+// error output during reads. Instead they are stored
+// and accessible (not concurrency safe!) via .Error().
+type SilentReader struct {
+	io.Reader
+	err error
+}
+
+// SilenceReader wraps an io.Reader within SilentReader{}.
+func SilenceReader(r io.Reader) *SilentReader {
+	return &SilentReader{Reader: r}
+}
+
+func (r *SilentReader) Read(b []byte) (int, error) {
+	n, err := r.Reader.Read(b)
+	if err != nil {
+		// Store error for now
+		if r.err == nil {
+			r.err = err
+		}
+
+		// Pretend we're happy
+		// to continue reading.
+		n = len(b)
+	}
+	return n, nil
+}
+
+func (r *SilentReader) Error() error {
+	return r.err
+}
+
+// SilentWriter wraps an io.Writer to silence any
+// error output during writes. Instead they are stored
+// and accessible (not concurrency safe!) via .Error().
+type SilentWriter struct {
+	io.Writer
+	err error
+}
+
+// SilenceWriter wraps an io.Writer within SilentWriter{}.
+func SilenceWriter(w io.Writer) *SilentWriter {
+	return &SilentWriter{Writer: w}
+}
+
+func (w *SilentWriter) Write(b []byte) (int, error) {
+	n, err := w.Writer.Write(b)
+	if err != nil {
+		// Store error for now
+		if w.err == nil {
+			w.err = err
+		}
+
+		// Pretend we're happy
+		// to continue writing.
+		n = len(b)
+	}
+	return n, nil
+}
+
+func (w *SilentWriter) Error() error {
+	return w.err
+}

internal/processing/media/getfile.go

@@ -19,7 +19,6 @@
 package media
 
 import (
-	"bufio"
 	"context"
 	"fmt"
 	"io"
@@ -29,7 +28,7 @@ import (
 	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
-	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/iotools"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
 	"github.com/superseriousbusiness/gotosocial/internal/transport"
 	"github.com/superseriousbusiness/gotosocial/internal/uris"
@@ -135,7 +134,6 @@ func (p *processor) getAttachmentContent(ctx context.Context, requestingAccount
 	}
 
 	var data media.DataFunc
-	var postDataCallback media.PostDataCallbackFunc
 
 	if mediaSize == media.SizeSmall {
 		// if it's the thumbnail that's requested then the user will have to wait a bit while we process the
@@ -155,7 +153,7 @@ func (p *processor) getAttachmentContent(ctx context.Context, requestingAccount
 		//
 		// this looks a bit like this:
 		//
-		//                http fetch                   buffered pipe
+		//                http fetch                       pipe
 		// remote server ------------> data function ----------------> api caller
 		//                                   |
 		//                                   | tee
@@ -163,54 +161,58 @@ func (p *processor) getAttachmentContent(ctx context.Context, requestingAccount
 		//                                   ▼
 		//                            instance storage
 
-		// Buffer each end of the pipe, so that if the caller drops the connection during the flow, the tee
+		// This pipe will connect the caller to the in-process media retrieval...
-		// reader can continue without having to worry about tee-ing into a closed or blocked pipe.
 		pipeReader, pipeWriter := io.Pipe()
-		bufferedWriter := bufio.NewWriterSize(pipeWriter, int(attachmentContent.ContentLength))
-		bufferedReader := bufio.NewReaderSize(pipeReader, int(attachmentContent.ContentLength))
 
-		// the caller will read from the buffered reader, so it doesn't matter if they drop out without reading everything
+		// Wrap the output pipe to silence any errors during the actual media
-		attachmentContent.Content = io.NopCloser(bufferedReader)
+		// streaming process. We catch the error later but they must be silenced
+		// during stream to prevent interruptions to storage of the actual media.
+		silencedWriter := iotools.SilenceWriter(pipeWriter)
 
+		// Pass the reader side of the pipe to the caller to slurp from.
+		attachmentContent.Content = pipeReader
+
+		// Create a data function which injects the writer end of the pipe
+		// into the data retrieval process. If something goes wrong while
+		// doing the data retrieval, we hang up the underlying pipeReader
+		// to indicate to the caller that no data is available. It's up to
+		// the caller of this processor function to handle that gracefully.
 		data = func(innerCtx context.Context) (io.ReadCloser, int64, error) {
 			t, err := p.transportController.NewTransportForUsername(innerCtx, requestingUsername)
 			if err != nil {
+				// propagate the transport error to read end of pipe.
+				_ = pipeWriter.CloseWithError(fmt.Errorf("error getting transport for user: %w", err))
 				return nil, 0, err
 			}
 
 			readCloser, fileSize, err := t.DereferenceMedia(transport.WithFastfail(innerCtx), remoteMediaIRI)
 			if err != nil {
+				// propagate the dereference error to read end of pipe.
+				_ = pipeWriter.CloseWithError(fmt.Errorf("error dereferencing media: %w", err))
 				return nil, 0, err
 			}
 
-			// Make a TeeReader so that everything read from the readCloser by the media manager will be written into the bufferedWriter.
+			// Make a TeeReader so that everything read from the readCloser,
-			// We wrap this in a teeReadCloser which implements io.ReadCloser, so that whoever uses the teeReader can close the readCloser
+			// aka the remote instance, will also be written into the pipe.
-			// when they're done with it.
+			teeReader := io.TeeReader(readCloser, silencedWriter)
-			trc := teeReadCloser{
-				teeReader: io.TeeReader(readCloser, bufferedWriter),
-				close:     readCloser.Close,
-			}
 
-			return trc, fileSize, nil
+			// Wrap teereader to implement original readcloser's close,
-		}
+			// and also ensuring that we close the pipe from write end.
-
+			return iotools.ReadFnCloser(teeReader, func() error {
-		// close the pipewriter after data has been piped into it, so the reader on the other side doesn't block;
-		// we don't need to close the reader here because that's the caller's responsibility
-		postDataCallback = func(innerCtx context.Context) error {
-			// close the underlying pipe writer when we're done with it
 				defer func() {
-				if err := pipeWriter.Close(); err != nil {
+					// We use the error (if any) encountered by the
-					log.Errorf("getAttachmentContent: error closing pipeWriter: %s", err)
+					// silenced writer to close connection to make sure it
-				}
+					// gets propagated to the attachment.Content reader.
+					_ = pipeWriter.CloseWithError(silencedWriter.Error())
 				}()
 
-			// and flush the buffered writer into the buffer of the reader
+				return readCloser.Close()
-			return bufferedWriter.Flush()
+			}), fileSize, nil
 		}
 	}
 
 	// put the media recached in the queue
-	processingMedia, err := p.mediaManager.RecacheMedia(ctx, data, postDataCallback, wantedMediaID)
+	processingMedia, err := p.mediaManager.RecacheMedia(ctx, data, nil, wantedMediaID)
 	if err != nil {
 		return nil, gtserror.NewErrorNotFound(fmt.Errorf("error recaching media: %s", err))
 	}

internal/processing/media/getfile_test.go

@@ -19,6 +19,7 @@
 package media_test
 
 import (
+	"bytes"
 	"context"
 	"io"
 	"path"
@@ -143,9 +144,13 @@ func (suite *GetFileTestSuite) TestGetRemoteFileUncachedInterrupted() {
 	suite.NotNil(content)
 
 	// only read the first kilobyte and then stop
-	b := make([]byte, 1024)
+	b := make([]byte, 0, 1024)
-	_, err = content.Content.Read(b)
+	if !testrig.WaitFor(func() bool {
-	suite.NoError(err)
+		read, err := io.CopyN(bytes.NewBuffer(b), content.Content, 1024)
+		return err == nil && read == 1024
+	}) {
+		suite.FailNow("timed out trying to read first 1024 bytes")
+	}
 
 	// close the reader
 	suite.NoError(content.Content.Close())

internal/processing/media/util.go

@@ -20,7 +20,6 @@ package media
 
 import (
 	"fmt"
-	"io"
 	"strconv"
 	"strings"
 )
@@ -62,16 +61,3 @@ func parseFocus(focus string) (focusx, focusy float32, err error) {
 	focusy = float32(fy)
 	return
 }
-
-type teeReadCloser struct {
-	teeReader io.Reader
-	close     func() error
-}
-
-func (t teeReadCloser) Read(p []byte) (n int, err error) {
-	return t.teeReader.Read(p)
-}
-
-func (t teeReadCloser) Close() error {
-	return t.close()
-}