303 lines
7.8 KiB
Go
303 lines
7.8 KiB
Go
// Copyright 2014 The Gogs Authors. All rights reserved.
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// Copyright 2018 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package markdown
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import (
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"fmt"
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"io"
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"strings"
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"sync"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/markup"
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"code.gitea.io/gitea/modules/markup/common"
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"code.gitea.io/gitea/modules/markup/markdown/callout"
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"code.gitea.io/gitea/modules/markup/markdown/math"
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"code.gitea.io/gitea/modules/setting"
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giteautil "code.gitea.io/gitea/modules/util"
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chromahtml "github.com/alecthomas/chroma/v2/formatters/html"
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"github.com/yuin/goldmark"
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highlighting "github.com/yuin/goldmark-highlighting/v2"
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meta "github.com/yuin/goldmark-meta"
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"github.com/yuin/goldmark/extension"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/renderer"
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"github.com/yuin/goldmark/renderer/html"
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"github.com/yuin/goldmark/util"
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)
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var (
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specMarkdown goldmark.Markdown
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specMarkdownOnce sync.Once
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)
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var (
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renderContextKey = parser.NewContextKey()
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renderConfigKey = parser.NewContextKey()
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)
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type limitWriter struct {
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w io.Writer
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sum int64
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limit int64
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}
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// Write implements the standard Write interface:
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func (l *limitWriter) Write(data []byte) (int, error) {
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leftToWrite := l.limit - l.sum
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if leftToWrite < int64(len(data)) {
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n, err := l.w.Write(data[:leftToWrite])
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l.sum += int64(n)
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if err != nil {
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return n, err
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}
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return n, fmt.Errorf("rendered content too large - truncating render")
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}
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n, err := l.w.Write(data)
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l.sum += int64(n)
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return n, err
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}
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// newParserContext creates a parser.Context with the render context set
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func newParserContext(ctx *markup.RenderContext) parser.Context {
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pc := parser.NewContext(parser.WithIDs(newPrefixedIDs()))
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pc.Set(renderContextKey, ctx)
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return pc
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}
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// SpecializedMarkdown sets up the Gitea specific markdown extensions
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func SpecializedMarkdown() goldmark.Markdown {
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specMarkdownOnce.Do(func() {
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specMarkdown = goldmark.New(
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goldmark.WithExtensions(
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extension.NewTable(
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extension.WithTableCellAlignMethod(extension.TableCellAlignAttribute)),
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extension.Strikethrough,
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extension.TaskList,
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extension.DefinitionList,
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common.FootnoteExtension,
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highlighting.NewHighlighting(
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highlighting.WithFormatOptions(
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chromahtml.WithClasses(true),
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chromahtml.PreventSurroundingPre(true),
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),
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highlighting.WithWrapperRenderer(func(w util.BufWriter, c highlighting.CodeBlockContext, entering bool) {
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if entering {
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language, _ := c.Language()
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if language == nil {
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language = []byte("text")
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}
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languageStr := string(language)
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preClasses := []string{"code-block"}
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if languageStr == "mermaid" || languageStr == "math" {
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preClasses = append(preClasses, "is-loading")
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}
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_, err := w.WriteString(`<pre class="` + strings.Join(preClasses, " ") + `">`)
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if err != nil {
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return
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}
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// include language-x class as part of commonmark spec
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_, err = w.WriteString(`<code class="chroma language-` + string(language) + `">`)
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if err != nil {
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return
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}
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} else {
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_, err := w.WriteString("</code></pre>")
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if err != nil {
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return
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}
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}
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}),
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),
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math.NewExtension(
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math.Enabled(setting.Markdown.EnableMath),
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),
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meta.Meta,
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),
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goldmark.WithParserOptions(
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parser.WithAttribute(),
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parser.WithAutoHeadingID(),
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parser.WithASTTransformers(
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util.Prioritized(&callout.GitHubCalloutTransformer{}, 9000),
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util.Prioritized(&ASTTransformer{}, 10000),
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),
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),
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goldmark.WithRendererOptions(
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html.WithUnsafe(),
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),
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)
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// Override the original Tasklist renderer!
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specMarkdown.Renderer().AddOptions(
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renderer.WithNodeRenderers(
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util.Prioritized(callout.NewGitHubCalloutHTMLRenderer(), 10),
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util.Prioritized(NewHTMLRenderer(), 10),
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),
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)
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})
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return specMarkdown
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}
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// actualRender renders Markdown to HTML without handling special links.
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func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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converter := SpecializedMarkdown()
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lw := &limitWriter{
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w: output,
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limit: setting.UI.MaxDisplayFileSize * 3,
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}
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// FIXME: should we include a timeout to abort the renderer if it takes too long?
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defer func() {
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err := recover()
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if err == nil {
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return
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}
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log.Warn("Unable to render markdown due to panic in goldmark: %v", err)
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if log.IsDebug() {
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log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2))
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}
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}()
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// FIXME: Don't read all to memory, but goldmark doesn't support
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pc := newParserContext(ctx)
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buf, err := io.ReadAll(input)
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if err != nil {
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log.Error("Unable to ReadAll: %v", err)
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return err
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}
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buf = giteautil.NormalizeEOL(buf)
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// Preserve original length.
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bufWithMetadataLength := len(buf)
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rc := &RenderConfig{
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Meta: renderMetaModeFromString(string(ctx.RenderMetaAs)),
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Icon: "table",
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Lang: "",
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}
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buf, _ = ExtractMetadataBytes(buf, rc)
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metaLength := bufWithMetadataLength - len(buf)
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if metaLength < 0 {
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metaLength = 0
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}
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rc.metaLength = metaLength
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pc.Set(renderConfigKey, rc)
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if err := converter.Convert(buf, lw, parser.WithContext(pc)); err != nil {
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log.Error("Unable to render: %v", err)
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return err
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}
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return nil
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}
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// Note: The output of this method must get sanitized.
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func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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defer func() {
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err := recover()
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if err == nil {
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return
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}
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log.Warn("Unable to render markdown due to panic in goldmark - will return raw bytes")
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if log.IsDebug() {
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log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2))
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}
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_, err = io.Copy(output, input)
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if err != nil {
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log.Error("io.Copy failed: %v", err)
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}
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}()
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return actualRender(ctx, input, output)
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}
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// MarkupName describes markup's name
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var MarkupName = "markdown"
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func init() {
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markup.RegisterRenderer(Renderer{})
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}
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// Renderer implements markup.Renderer
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type Renderer struct{}
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var _ markup.PostProcessRenderer = (*Renderer)(nil)
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// Name implements markup.Renderer
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func (Renderer) Name() string {
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return MarkupName
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}
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// NeedPostProcess implements markup.PostProcessRenderer
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func (Renderer) NeedPostProcess() bool { return true }
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// Extensions implements markup.Renderer
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func (Renderer) Extensions() []string {
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return setting.Markdown.FileExtensions
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}
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// SanitizerRules implements markup.Renderer
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func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
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return []setting.MarkupSanitizerRule{}
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}
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// Render implements markup.Renderer
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func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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return render(ctx, input, output)
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}
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// Render renders Markdown to HTML with all specific handling stuff.
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func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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if ctx.Type == "" {
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ctx.Type = MarkupName
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}
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return markup.Render(ctx, input, output)
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}
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// RenderString renders Markdown string to HTML with all specific handling stuff and return string
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func RenderString(ctx *markup.RenderContext, content string) (string, error) {
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var buf strings.Builder
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if err := Render(ctx, strings.NewReader(content), &buf); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// RenderRaw renders Markdown to HTML without handling special links.
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func RenderRaw(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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rd, wr := io.Pipe()
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defer func() {
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_ = rd.Close()
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_ = wr.Close()
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}()
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go func() {
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if err := render(ctx, input, wr); err != nil {
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_ = wr.CloseWithError(err)
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return
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}
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_ = wr.Close()
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}()
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return markup.SanitizeReader(rd, "", output)
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}
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// RenderRawString renders Markdown to HTML without handling special links and return string
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func RenderRawString(ctx *markup.RenderContext, content string) (string, error) {
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var buf strings.Builder
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if err := RenderRaw(ctx, strings.NewReader(content), &buf); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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