// Copyright 2014 The Gogs Authors. All rights reserved. // Copyright 2018 The Gitea Authors. All rights reserved. // SPDX-License-Identifier: MIT package markdown import ( "fmt" "io" "strings" "sync" "code.gitea.io/gitea/modules/log" "code.gitea.io/gitea/modules/markup" "code.gitea.io/gitea/modules/markup/common" "code.gitea.io/gitea/modules/markup/markdown/math" "code.gitea.io/gitea/modules/setting" giteautil "code.gitea.io/gitea/modules/util" chromahtml "github.com/alecthomas/chroma/v2/formatters/html" "github.com/yuin/goldmark" highlighting "github.com/yuin/goldmark-highlighting/v2" meta "github.com/yuin/goldmark-meta" "github.com/yuin/goldmark/extension" "github.com/yuin/goldmark/parser" "github.com/yuin/goldmark/renderer" "github.com/yuin/goldmark/renderer/html" "github.com/yuin/goldmark/util" ) var ( specMarkdown goldmark.Markdown specMarkdownOnce sync.Once ) var ( renderContextKey = parser.NewContextKey() renderConfigKey = parser.NewContextKey() ) type limitWriter struct { w io.Writer sum int64 limit int64 } // Write implements the standard Write interface: func (l *limitWriter) Write(data []byte) (int, error) { leftToWrite := l.limit - l.sum if leftToWrite < int64(len(data)) { n, err := l.w.Write(data[:leftToWrite]) l.sum += int64(n) if err != nil { return n, err } return n, fmt.Errorf("rendered content too large - truncating render") } n, err := l.w.Write(data) l.sum += int64(n) return n, err } // newParserContext creates a parser.Context with the render context set func newParserContext(ctx *markup.RenderContext) parser.Context { pc := parser.NewContext(parser.WithIDs(newPrefixedIDs())) pc.Set(renderContextKey, ctx) return pc } // SpecializedMarkdown sets up the Gitea specific markdown extensions func SpecializedMarkdown() goldmark.Markdown { specMarkdownOnce.Do(func() { specMarkdown = goldmark.New( goldmark.WithExtensions( extension.NewTable( extension.WithTableCellAlignMethod(extension.TableCellAlignAttribute)), extension.Strikethrough, extension.TaskList, extension.DefinitionList, common.FootnoteExtension, highlighting.NewHighlighting( highlighting.WithFormatOptions( chromahtml.WithClasses(true), chromahtml.PreventSurroundingPre(true), ), highlighting.WithWrapperRenderer(func(w util.BufWriter, c highlighting.CodeBlockContext, entering bool) { if entering { language, _ := c.Language() if language == nil { language = []byte("text") } languageStr := string(language) preClasses := []string{"code-block"} if languageStr == "mermaid" || languageStr == "math" { preClasses = append(preClasses, "is-loading") } _, err := w.WriteString(`
`)
							if err != nil {
								return
							}

							// include language-x class as part of commonmark spec
							// the "display" class is used by "js/markup/math.js" to render the code element as a block
							_, err = w.WriteString(``)
							if err != nil {
								return
							}
						} else {
							_, err := w.WriteString("
") if err != nil { return } } }), ), math.NewExtension( math.Enabled(setting.Markdown.EnableMath), ), meta.Meta, ), goldmark.WithParserOptions( parser.WithAttribute(), parser.WithAutoHeadingID(), parser.WithASTTransformers( util.Prioritized(&ASTTransformer{}, 10000), ), ), goldmark.WithRendererOptions( html.WithUnsafe(), ), ) // Override the original Tasklist renderer! specMarkdown.Renderer().AddOptions( renderer.WithNodeRenderers( util.Prioritized(NewHTMLRenderer(), 10), ), ) }) return specMarkdown } // actualRender renders Markdown to HTML without handling special links. func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { converter := SpecializedMarkdown() lw := &limitWriter{ w: output, limit: setting.UI.MaxDisplayFileSize * 3, } // FIXME: should we include a timeout to abort the renderer if it takes too long? defer func() { err := recover() if err == nil { return } log.Warn("Unable to render markdown due to panic in goldmark: %v", err) if log.IsDebug() { log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2)) } }() // FIXME: Don't read all to memory, but goldmark doesn't support pc := newParserContext(ctx) buf, err := io.ReadAll(input) if err != nil { log.Error("Unable to ReadAll: %v", err) return err } buf = giteautil.NormalizeEOL(buf) // Preserve original length. bufWithMetadataLength := len(buf) rc := &RenderConfig{ Meta: renderMetaModeFromString(string(ctx.RenderMetaAs)), Icon: "table", Lang: "", } buf, _ = ExtractMetadataBytes(buf, rc) metaLength := bufWithMetadataLength - len(buf) if metaLength < 0 { metaLength = 0 } rc.metaLength = metaLength pc.Set(renderConfigKey, rc) if err := converter.Convert(buf, lw, parser.WithContext(pc)); err != nil { log.Error("Unable to render: %v", err) return err } return nil } // Note: The output of this method must get sanitized. func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { defer func() { err := recover() if err == nil { return } log.Warn("Unable to render markdown due to panic in goldmark - will return raw bytes") if log.IsDebug() { log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2)) } _, err = io.Copy(output, input) if err != nil { log.Error("io.Copy failed: %v", err) } }() return actualRender(ctx, input, output) } // MarkupName describes markup's name var MarkupName = "markdown" func init() { markup.RegisterRenderer(Renderer{}) } // Renderer implements markup.Renderer type Renderer struct{} var _ markup.PostProcessRenderer = (*Renderer)(nil) // Name implements markup.Renderer func (Renderer) Name() string { return MarkupName } // NeedPostProcess implements markup.PostProcessRenderer func (Renderer) NeedPostProcess() bool { return true } // Extensions implements markup.Renderer func (Renderer) Extensions() []string { return setting.Markdown.FileExtensions } // SanitizerRules implements markup.Renderer func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule { return []setting.MarkupSanitizerRule{} } // Render implements markup.Renderer func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { return render(ctx, input, output) } // Render renders Markdown to HTML with all specific handling stuff. func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { if ctx.Type == "" { ctx.Type = MarkupName } return markup.Render(ctx, input, output) } // RenderString renders Markdown string to HTML with all specific handling stuff and return string func RenderString(ctx *markup.RenderContext, content string) (string, error) { var buf strings.Builder if err := Render(ctx, strings.NewReader(content), &buf); err != nil { return "", err } return buf.String(), nil } // RenderRaw renders Markdown to HTML without handling special links. func RenderRaw(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { rd, wr := io.Pipe() defer func() { _ = rd.Close() _ = wr.Close() }() go func() { if err := render(ctx, input, wr); err != nil { _ = wr.CloseWithError(err) return } _ = wr.Close() }() return markup.SanitizeReader(rd, "", output) } // RenderRawString renders Markdown to HTML without handling special links and return string func RenderRawString(ctx *markup.RenderContext, content string) (string, error) { var buf strings.Builder if err := RenderRaw(ctx, strings.NewReader(content), &buf); err != nil { return "", err } return buf.String(), nil }