// 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 ( converter goldmark.Markdown once = sync.Once{} ) var ( urlPrefixKey = parser.NewContextKey() isWikiKey = parser.NewContextKey() renderMetasKey = parser.NewContextKey() 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(urlPrefixKey, ctx.URLPrefix) pc.Set(isWikiKey, ctx.IsWiki) pc.Set(renderMetasKey, ctx.Metas) pc.Set(renderContextKey, ctx) return pc } // actualRender renders Markdown to HTML without handling special links. func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { once.Do(func() { converter = 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
_, 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!
converter.Renderer().AddOptions(
renderer.WithNodeRenderers(
util.Prioritized(NewHTMLRenderer(), 10),
),
)
})
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)
rc := &RenderConfig{
Meta: "table",
Icon: "table",
Lang: "",
}
buf, _ = ExtractMetadataBytes(buf, rc)
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
}