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179 lines
5.1 KiB
179 lines
5.1 KiB
// Copyright 2014 The Gogs Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package charset
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import (
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"bytes"
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"fmt"
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"strings"
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"unicode/utf8"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/setting"
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"github.com/gogs/chardet"
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"golang.org/x/net/html/charset"
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"golang.org/x/text/transform"
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)
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// UTF8BOM is the utf-8 byte-order marker
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var UTF8BOM = []byte{'\xef', '\xbb', '\xbf'}
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// ToUTF8WithErr converts content to UTF8 encoding
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func ToUTF8WithErr(content []byte) (string, error) {
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charsetLabel, err := DetectEncoding(content)
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if err != nil {
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return "", err
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} else if charsetLabel == "UTF-8" {
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return string(RemoveBOMIfPresent(content)), nil
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}
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encoding, _ := charset.Lookup(charsetLabel)
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if encoding == nil {
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return string(content), fmt.Errorf("Unknown encoding: %s", charsetLabel)
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}
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// If there is an error, we concatenate the nicely decoded part and the
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// original left over. This way we won't lose much data.
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result, n, err := transform.Bytes(encoding.NewDecoder(), content)
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if err != nil {
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result = append(result, content[n:]...)
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}
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result = RemoveBOMIfPresent(result)
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return string(result), err
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}
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// ToUTF8WithFallback detects the encoding of content and coverts to UTF-8 if possible
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func ToUTF8WithFallback(content []byte) []byte {
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charsetLabel, err := DetectEncoding(content)
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if err != nil || charsetLabel == "UTF-8" {
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return RemoveBOMIfPresent(content)
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}
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encoding, _ := charset.Lookup(charsetLabel)
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if encoding == nil {
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return content
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}
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// If there is an error, we concatenate the nicely decoded part and the
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// original left over. This way we won't lose data.
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result, n, err := transform.Bytes(encoding.NewDecoder(), content)
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if err != nil {
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return append(result, content[n:]...)
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}
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return RemoveBOMIfPresent(result)
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}
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// ToUTF8 converts content to UTF8 encoding and ignore error
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func ToUTF8(content string) string {
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res, _ := ToUTF8WithErr([]byte(content))
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return res
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}
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// ToUTF8DropErrors makes sure the return string is valid utf-8; attempts conversion if possible
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func ToUTF8DropErrors(content []byte) []byte {
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charsetLabel, err := DetectEncoding(content)
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if err != nil || charsetLabel == "UTF-8" {
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return RemoveBOMIfPresent(content)
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}
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encoding, _ := charset.Lookup(charsetLabel)
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if encoding == nil {
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return content
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}
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// We ignore any non-decodable parts from the file.
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// Some parts might be lost
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var decoded []byte
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decoder := encoding.NewDecoder()
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idx := 0
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for {
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result, n, err := transform.Bytes(decoder, content[idx:])
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decoded = append(decoded, result...)
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if err == nil {
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break
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}
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decoded = append(decoded, ' ')
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idx = idx + n + 1
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if idx >= len(content) {
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break
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}
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}
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return RemoveBOMIfPresent(decoded)
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}
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// RemoveBOMIfPresent removes a UTF-8 BOM from a []byte
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func RemoveBOMIfPresent(content []byte) []byte {
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if len(content) > 2 && bytes.Equal(content[0:3], UTF8BOM) {
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return content[3:]
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}
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return content
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}
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// DetectEncoding detect the encoding of content
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func DetectEncoding(content []byte) (string, error) {
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if utf8.Valid(content) {
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log.Debug("Detected encoding: utf-8 (fast)")
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return "UTF-8", nil
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}
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textDetector := chardet.NewTextDetector()
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var detectContent []byte
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if len(content) < 1024 {
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// Check if original content is valid
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if _, err := textDetector.DetectBest(content); err != nil {
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return "", err
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}
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times := 1024 / len(content)
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detectContent = make([]byte, 0, times*len(content))
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for i := 0; i < times; i++ {
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detectContent = append(detectContent, content...)
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}
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} else {
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detectContent = content
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}
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// Now we can't use DetectBest or just results[0] because the result isn't stable - so we need a tie break
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results, err := textDetector.DetectAll(detectContent)
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if err != nil {
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if err == chardet.NotDetectedError && len(setting.Repository.AnsiCharset) > 0 {
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log.Debug("Using default AnsiCharset: %s", setting.Repository.AnsiCharset)
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return setting.Repository.AnsiCharset, nil
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}
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return "", err
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}
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topConfidence := results[0].Confidence
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topResult := results[0]
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priority, has := setting.Repository.DetectedCharsetScore[strings.ToLower(strings.TrimSpace(topResult.Charset))]
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for _, result := range results {
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// As results are sorted in confidence order - if we have a different confidence
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// we know it's less than the current confidence and can break out of the loop early
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if result.Confidence != topConfidence {
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break
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}
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// Otherwise check if this results is earlier in the DetectedCharsetOrder than our current top guesss
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resultPriority, resultHas := setting.Repository.DetectedCharsetScore[strings.ToLower(strings.TrimSpace(result.Charset))]
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if resultHas && (!has || resultPriority < priority) {
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topResult = result
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priority = resultPriority
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has = true
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}
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}
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// FIXME: to properly decouple this function the fallback ANSI charset should be passed as an argument
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if topResult.Charset != "UTF-8" && len(setting.Repository.AnsiCharset) > 0 {
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log.Debug("Using default AnsiCharset: %s", setting.Repository.AnsiCharset)
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return setting.Repository.AnsiCharset, err
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}
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log.Debug("Detected encoding: %s", topResult.Charset)
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return topResult.Charset, err
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}
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