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forgejo/modules/markup/markdown/markdown.go
zeripath ed31ddc29a
Fix several render issues (#14986)
* Fix an issue with panics related to attributes
* Wrap goldmark render in a recovery function
* Reduce memory use in render emoji
* Use a pipe for rendering goldmark - still needs more work and a limiter

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
2021-03-16 00:20:05 +01:00

265 lines
7 KiB
Go

// Copyright 2014 The Gogs Authors. All rights reserved.
// Copyright 2018 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
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/setting"
giteautil "code.gitea.io/gitea/modules/util"
chromahtml "github.com/alecthomas/chroma/formatters/html"
"github.com/yuin/goldmark"
highlighting "github.com/yuin/goldmark-highlighting"
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
var once = sync.Once{}
var urlPrefixKey = parser.NewContextKey()
var isWikiKey = parser.NewContextKey()
var renderMetasKey = parser.NewContextKey()
type closesWithError interface {
io.WriteCloser
CloseWithError(err error) error
}
type limitWriter struct {
w closesWithError
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
}
_ = l.w.Close()
return n, fmt.Errorf("Rendered content too large - truncating render")
}
n, err := l.w.Write(data)
l.sum += int64(n)
return n, err
}
// Close closes the writer
func (l *limitWriter) Close() error {
return l.w.Close()
}
// CloseWithError closes the writer
func (l *limitWriter) CloseWithError(err error) error {
return l.w.CloseWithError(err)
}
// NewGiteaParseContext creates a parser.Context with the gitea context set
func NewGiteaParseContext(urlPrefix string, metas map[string]string, isWiki bool) parser.Context {
pc := parser.NewContext(parser.WithIDs(newPrefixedIDs()))
pc.Set(urlPrefixKey, urlPrefix)
pc.Set(isWikiKey, isWiki)
pc.Set(renderMetasKey, metas)
return pc
}
// actualRender renders Markdown to HTML without handling special links.
func actualRender(body []byte, urlPrefix string, metas map[string]string, wikiMarkdown bool) []byte {
once.Do(func() {
converter = goldmark.New(
goldmark.WithExtensions(extension.Table,
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{}
if languageStr == "mermaid" {
preClasses = append(preClasses, "is-loading")
}
if len(preClasses) > 0 {
_, err := w.WriteString(`<pre class="` + strings.Join(preClasses, " ") + `">`)
if err != nil {
return
}
} else {
_, err := w.WriteString(`<pre>`)
if err != nil {
return
}
}
// include language-x class as part of commonmark spec
_, err := w.WriteString(`<code class="chroma language-` + string(language) + `">`)
if err != nil {
return
}
} else {
_, err := w.WriteString("</code></pre>")
if err != nil {
return
}
}
}),
),
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),
),
)
})
rd, wr := io.Pipe()
defer func() {
_ = rd.Close()
_ = wr.Close()
}()
lw := &limitWriter{
w: wr,
limit: setting.UI.MaxDisplayFileSize * 3,
}
// FIXME: should we include a timeout that closes the pipe to abort the parser and sanitizer if it takes too long?
go func() {
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, string(log.Stack(2)))
}
_ = lw.CloseWithError(fmt.Errorf("%v", err))
}()
pc := NewGiteaParseContext(urlPrefix, metas, wikiMarkdown)
if err := converter.Convert(giteautil.NormalizeEOL(body), lw, parser.WithContext(pc)); err != nil {
log.Error("Unable to render: %v", err)
_ = lw.CloseWithError(err)
return
}
_ = lw.Close()
}()
return markup.SanitizeReader(rd).Bytes()
}
func render(body []byte, urlPrefix string, metas map[string]string, wikiMarkdown bool) (ret []byte) {
defer func() {
err := recover()
if err == nil {
return
}
log.Warn("Unable to render markdown due to panic in goldmark - will return sanitized raw bytes")
if log.IsDebug() {
log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2)))
}
ret = markup.SanitizeBytes(body)
}()
return actualRender(body, urlPrefix, metas, wikiMarkdown)
}
var (
// MarkupName describes markup's name
MarkupName = "markdown"
)
func init() {
markup.RegisterParser(Parser{})
}
// Parser implements markup.Parser
type Parser struct{}
// Name implements markup.Parser
func (Parser) Name() string {
return MarkupName
}
// Extensions implements markup.Parser
func (Parser) Extensions() []string {
return setting.Markdown.FileExtensions
}
// Render implements markup.Parser
func (Parser) Render(rawBytes []byte, urlPrefix string, metas map[string]string, isWiki bool) []byte {
return render(rawBytes, urlPrefix, metas, isWiki)
}
// Render renders Markdown to HTML with all specific handling stuff.
func Render(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
return markup.Render("a.md", rawBytes, urlPrefix, metas)
}
// RenderRaw renders Markdown to HTML without handling special links.
func RenderRaw(body []byte, urlPrefix string, wikiMarkdown bool) []byte {
return render(body, urlPrefix, map[string]string{}, wikiMarkdown)
}
// RenderString renders Markdown to HTML with special links and returns string type.
func RenderString(raw, urlPrefix string, metas map[string]string) string {
return markup.RenderString("a.md", raw, urlPrefix, metas)
}
// RenderWiki renders markdown wiki page to HTML and return HTML string
func RenderWiki(rawBytes []byte, urlPrefix string, metas map[string]string) string {
return markup.RenderWiki("a.md", rawBytes, urlPrefix, metas)
}
// IsMarkdownFile reports whether name looks like a Markdown file
// based on its extension.
func IsMarkdownFile(name string) bool {
return markup.IsMarkupFile(name, MarkupName)
}