Template
1
0
Fork 0
mirror of https://codeberg.org/forgejo/forgejo synced 2024-12-05 02:54:46 +01:00
forgejo/modules/markup/renderer.go
silverwind 32d9c47ec7
Add RTL rendering support to Markdown (#24816)
Support RTL content in Markdown:


![image](https://github.com/go-gitea/gitea/assets/115237/dedb1b0c-2f05-40dc-931a-0d9dc81f7c97)

Example document:
https://try.gitea.io/silverwind/symlink-test/src/branch/master/bidi-text.md
Same on GitHub:
https://github.com/silverwind/symlink-test/blob/master/bidi-text.md

`dir=auto` enables a browser heuristic that sets the text direction
automatically. It is the only way to get automatic text direction.

Ref: https://codeberg.org/Codeberg/Community/issues/1021

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
2023-05-20 23:02:52 +02:00

345 lines
9.1 KiB
Go

// Copyright 2017 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package markup
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"net/url"
"path/filepath"
"strings"
"sync"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/setting"
"github.com/yuin/goldmark/ast"
)
type RenderMetaMode string
const (
RenderMetaAsDetails RenderMetaMode = "details" // default
RenderMetaAsNone RenderMetaMode = "none"
RenderMetaAsTable RenderMetaMode = "table"
)
type ProcessorHelper struct {
IsUsernameMentionable func(ctx context.Context, username string) bool
ElementDir string // the direction of the elements, eg: "ltr", "rtl", "auto", default to no direction attribute
}
var DefaultProcessorHelper ProcessorHelper
// Init initialize regexps for markdown parsing
func Init(ph *ProcessorHelper) {
if ph != nil {
DefaultProcessorHelper = *ph
}
NewSanitizer()
if len(setting.Markdown.CustomURLSchemes) > 0 {
CustomLinkURLSchemes(setting.Markdown.CustomURLSchemes)
}
// since setting maybe changed extensions, this will reload all renderer extensions mapping
extRenderers = make(map[string]Renderer)
for _, renderer := range renderers {
for _, ext := range renderer.Extensions() {
extRenderers[strings.ToLower(ext)] = renderer
}
}
}
// Header holds the data about a header.
type Header struct {
Level int
Text string
ID string
}
// RenderContext represents a render context
type RenderContext struct {
Ctx context.Context
RelativePath string // relative path from tree root of the branch
Type string
IsWiki bool
URLPrefix string
Metas map[string]string
DefaultLink string
GitRepo *git.Repository
ShaExistCache map[string]bool
cancelFn func()
SidebarTocNode ast.Node
RenderMetaAs RenderMetaMode
InStandalonePage bool // used by external render. the router "/org/repo/render/..." will output the rendered content in a standalone page
}
// Cancel runs any cleanup functions that have been registered for this Ctx
func (ctx *RenderContext) Cancel() {
if ctx == nil {
return
}
ctx.ShaExistCache = map[string]bool{}
if ctx.cancelFn == nil {
return
}
ctx.cancelFn()
}
// AddCancel adds the provided fn as a Cleanup for this Ctx
func (ctx *RenderContext) AddCancel(fn func()) {
if ctx == nil {
return
}
oldCancelFn := ctx.cancelFn
if oldCancelFn == nil {
ctx.cancelFn = fn
return
}
ctx.cancelFn = func() {
defer oldCancelFn()
fn()
}
}
// Renderer defines an interface for rendering markup file to HTML
type Renderer interface {
Name() string // markup format name
Extensions() []string
SanitizerRules() []setting.MarkupSanitizerRule
Render(ctx *RenderContext, input io.Reader, output io.Writer) error
}
// PostProcessRenderer defines an interface for renderers who need post process
type PostProcessRenderer interface {
NeedPostProcess() bool
}
// PostProcessRenderer defines an interface for external renderers
type ExternalRenderer interface {
// SanitizerDisabled disabled sanitize if return true
SanitizerDisabled() bool
// DisplayInIFrame represents whether render the content with an iframe
DisplayInIFrame() bool
}
// RendererContentDetector detects if the content can be rendered
// by specified renderer
type RendererContentDetector interface {
CanRender(filename string, input io.Reader) bool
}
var (
extRenderers = make(map[string]Renderer)
renderers = make(map[string]Renderer)
)
// RegisterRenderer registers a new markup file renderer
func RegisterRenderer(renderer Renderer) {
renderers[renderer.Name()] = renderer
for _, ext := range renderer.Extensions() {
extRenderers[strings.ToLower(ext)] = renderer
}
}
// GetRendererByFileName get renderer by filename
func GetRendererByFileName(filename string) Renderer {
extension := strings.ToLower(filepath.Ext(filename))
return extRenderers[extension]
}
// GetRendererByType returns a renderer according type
func GetRendererByType(tp string) Renderer {
return renderers[tp]
}
// DetectRendererType detects the markup type of the content
func DetectRendererType(filename string, input io.Reader) string {
buf, err := io.ReadAll(input)
if err != nil {
return ""
}
for _, renderer := range renderers {
if detector, ok := renderer.(RendererContentDetector); ok && detector.CanRender(filename, bytes.NewReader(buf)) {
return renderer.Name()
}
}
return ""
}
// Render renders markup file to HTML with all specific handling stuff.
func Render(ctx *RenderContext, input io.Reader, output io.Writer) error {
if ctx.Type != "" {
return renderByType(ctx, input, output)
} else if ctx.RelativePath != "" {
return renderFile(ctx, input, output)
}
return errors.New("Render options both filename and type missing")
}
// RenderString renders Markup string to HTML with all specific handling stuff and return string
func RenderString(ctx *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
}
type nopCloser struct {
io.Writer
}
func (nopCloser) Close() error { return nil }
func renderIFrame(ctx *RenderContext, output io.Writer) error {
// set height="0" ahead, otherwise the scrollHeight would be max(150, realHeight)
// at the moment, only "allow-scripts" is allowed for sandbox mode.
// "allow-same-origin" should never be used, it leads to XSS attack, and it makes the JS in iframe can access parent window's config and CSRF token
// TODO: when using dark theme, if the rendered content doesn't have proper style, the default text color is black, which is not easy to read
_, err := io.WriteString(output, fmt.Sprintf(`
<iframe src="%s/%s/%s/render/%s/%s"
name="giteaExternalRender"
onload="this.height=giteaExternalRender.document.documentElement.scrollHeight"
width="100%%" height="0" scrolling="no" frameborder="0" style="overflow: hidden"
sandbox="allow-scripts"
></iframe>`,
setting.AppSubURL,
url.PathEscape(ctx.Metas["user"]),
url.PathEscape(ctx.Metas["repo"]),
ctx.Metas["BranchNameSubURL"],
url.PathEscape(ctx.RelativePath),
))
return err
}
func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Writer) error {
var wg sync.WaitGroup
var err error
pr, pw := io.Pipe()
defer func() {
_ = pr.Close()
_ = pw.Close()
}()
var pr2 io.ReadCloser
var pw2 io.WriteCloser
var sanitizerDisabled bool
if r, ok := renderer.(ExternalRenderer); ok {
sanitizerDisabled = r.SanitizerDisabled()
}
if !sanitizerDisabled {
pr2, pw2 = io.Pipe()
defer func() {
_ = pr2.Close()
_ = pw2.Close()
}()
wg.Add(1)
go func() {
err = SanitizeReader(pr2, renderer.Name(), output)
_ = pr2.Close()
wg.Done()
}()
} else {
pw2 = nopCloser{output}
}
wg.Add(1)
go func() {
if r, ok := renderer.(PostProcessRenderer); ok && r.NeedPostProcess() {
err = PostProcess(ctx, pr, pw2)
} else {
_, err = io.Copy(pw2, pr)
}
_ = pr.Close()
_ = pw2.Close()
wg.Done()
}()
if err1 := renderer.Render(ctx, input, pw); err1 != nil {
return err1
}
_ = pw.Close()
wg.Wait()
return err
}
// ErrUnsupportedRenderType represents
type ErrUnsupportedRenderType struct {
Type string
}
func (err ErrUnsupportedRenderType) Error() string {
return fmt.Sprintf("Unsupported render type: %s", err.Type)
}
func renderByType(ctx *RenderContext, input io.Reader, output io.Writer) error {
if renderer, ok := renderers[ctx.Type]; ok {
return render(ctx, renderer, input, output)
}
return ErrUnsupportedRenderType{ctx.Type}
}
// ErrUnsupportedRenderExtension represents the error when extension doesn't supported to render
type ErrUnsupportedRenderExtension struct {
Extension string
}
func IsErrUnsupportedRenderExtension(err error) bool {
_, ok := err.(ErrUnsupportedRenderExtension)
return ok
}
func (err ErrUnsupportedRenderExtension) Error() string {
return fmt.Sprintf("Unsupported render extension: %s", err.Extension)
}
func renderFile(ctx *RenderContext, input io.Reader, output io.Writer) error {
extension := strings.ToLower(filepath.Ext(ctx.RelativePath))
if renderer, ok := extRenderers[extension]; ok {
if r, ok := renderer.(ExternalRenderer); ok && r.DisplayInIFrame() {
if !ctx.InStandalonePage {
// for an external render, it could only output its content in a standalone page
// otherwise, a <iframe> should be outputted to embed the external rendered page
return renderIFrame(ctx, output)
}
}
return render(ctx, renderer, input, output)
}
return ErrUnsupportedRenderExtension{extension}
}
// Type returns if markup format via the filename
func Type(filename string) string {
if parser := GetRendererByFileName(filename); parser != nil {
return parser.Name()
}
return ""
}
// IsMarkupFile reports whether file is a markup type file
func IsMarkupFile(name, markup string) bool {
if parser := GetRendererByFileName(name); parser != nil {
return parser.Name() == markup
}
return false
}
func PreviewableExtensions() []string {
extensions := make([]string, 0, len(extRenderers))
for extension := range extRenderers {
extensions = append(extensions, extension)
}
return extensions
}