Fix bug when viewing the commit diff page with non-ANSI files (#36149) (#36150)

Backport #36149

modules/charset/charset.go

@@ -26,9 +26,11 @@ type ConvertOpts struct {
 	KeepBOM bool
 }
 
+var ToUTF8WithFallbackReaderPrefetchSize = 16 * 1024
+
 // ToUTF8WithFallbackReader detects the encoding of content and converts to UTF-8 reader if possible
 func ToUTF8WithFallbackReader(rd io.Reader, opts ConvertOpts) io.Reader {
-	buf := make([]byte, 2048)
+	buf := make([]byte, ToUTF8WithFallbackReaderPrefetchSize)
 	n, err := util.ReadAtMost(rd, buf)
 	if err != nil {
 		return io.MultiReader(bytes.NewReader(MaybeRemoveBOM(buf[:n], opts)), rd)
@@ -41,6 +43,7 @@ func ToUTF8WithFallbackReader(rd io.Reader, opts ConvertOpts) io.Reader {
 
 	encoding, _ := charset.Lookup(charsetLabel)
 	if encoding == nil {
+		log.Error("Unknown encoding: %s", charsetLabel)
 		return io.MultiReader(bytes.NewReader(buf[:n]), rd)
 	}
 
@@ -54,17 +57,18 @@ func ToUTF8WithFallbackReader(rd io.Reader, opts ConvertOpts) io.Reader {
 }
 
 // ToUTF8 converts content to UTF8 encoding
-func ToUTF8(content []byte, opts ConvertOpts) (string, error) {
+func ToUTF8(content []byte, opts ConvertOpts) ([]byte, error) {
 	charsetLabel, err := DetectEncoding(content)
 	if err != nil {
-		return "", err
+		return content, err
 	} else if charsetLabel == "UTF-8" {
-		return string(MaybeRemoveBOM(content, opts)), nil
+		return MaybeRemoveBOM(content, opts), nil
 	}
 
 	encoding, _ := charset.Lookup(charsetLabel)
 	if encoding == nil {
-		return string(content), fmt.Errorf("Unknown encoding: %s", charsetLabel)
+		log.Error("Unknown encoding: %s", charsetLabel)
+		return content, fmt.Errorf("unknown encoding: %s", charsetLabel)
 	}
 
 	// If there is an error, we concatenate the nicely decoded part and the
@@ -76,7 +80,7 @@ func ToUTF8(content []byte, opts ConvertOpts) (string, error) {
 
 	result = MaybeRemoveBOM(result, opts)
 
-	return string(result), err
+	return result, err
 }
 
 // ToUTF8WithFallback detects the encoding of content and converts to UTF-8 if possible
@@ -94,6 +98,7 @@ func ToUTF8DropErrors(content []byte, opts ConvertOpts) []byte {
 
 	encoding, _ := charset.Lookup(charsetLabel)
 	if encoding == nil {
+		log.Error("Unknown encoding: %s", charsetLabel)
 		return content
 	}
 
@@ -130,28 +135,37 @@ func MaybeRemoveBOM(content []byte, opts ConvertOpts) []byte {
 }
 
 // DetectEncoding detect the encoding of content
-func DetectEncoding(content []byte) (string, error) {
+// it always returns a detected or guessed "encoding" string, no matter error happens or not
+func DetectEncoding(content []byte) (encoding string, _ error) {
 	// First we check if the content represents valid utf8 content excepting a truncated character at the end.
 
 	// Now we could decode all the runes in turn but this is not necessarily the cheapest thing to do
-	// instead we walk backwards from the end to trim off a the incomplete character
+	// instead we walk backwards from the end to trim off the incomplete character
 	toValidate := content
 	end := len(toValidate) - 1
 
-	if end < 0 {
-		// no-op
-	} else if toValidate[end]>>5 == 0b110 {
-		// Incomplete 1 byte extension e.g. © <c2><a9> which has been truncated to <c2>
-		toValidate = toValidate[:end]
-	} else if end > 0 && toValidate[end]>>6 == 0b10 && toValidate[end-1]>>4 == 0b1110 {
-		// Incomplete 2 byte extension e.g. ⛔ <e2><9b><94> which has been truncated to <e2><9b>
-		toValidate = toValidate[:end-1]
-	} else if end > 1 && toValidate[end]>>6 == 0b10 && toValidate[end-1]>>6 == 0b10 && toValidate[end-2]>>3 == 0b11110 {
-		// Incomplete 3 byte extension e.g. 💩 <f0><9f><92><a9> which has been truncated to <f0><9f><92>
-		toValidate = toValidate[:end-2]
+	// U+0000   U+007F 	  0yyyzzzz
+	// U+0080   U+07FF 	  110xxxyy 	10yyzzzz
+	// U+0800   U+FFFF 	  1110wwww 	10xxxxyy 	10yyzzzz
+	// U+010000 U+10FFFF 	11110uvv 	10vvwwww 	10xxxxyy 	10yyzzzz
+	cnt := 0
+	for end >= 0 && cnt < 4 {
+		c := toValidate[end]
+		if c>>5 == 0b110 || c>>4 == 0b1110 || c>>3 == 0b11110 {
+			// a leading byte
+			toValidate = toValidate[:end]
+			break
+		} else if c>>6 == 0b10 {
+			// a continuation byte
+			end--
+		} else {
+			// not an utf-8 byte
+			break
+		}
+		cnt++
 	}
+
 	if utf8.Valid(toValidate) {
-		log.Debug("Detected encoding: utf-8 (fast)")
 		return "UTF-8", nil
 	}
 
@@ -160,7 +174,7 @@ func DetectEncoding(content []byte) (string, error) {
 	if len(content) < 1024 {
 		// Check if original content is valid
 		if _, err := textDetector.DetectBest(content); err != nil {
-			return "", err
+			return util.IfZero(setting.Repository.AnsiCharset, "UTF-8"), err
 		}
 		times := 1024 / len(content)
 		detectContent = make([]byte, 0, times*len(content))
@@ -171,14 +185,10 @@ func DetectEncoding(content []byte) (string, error) {
 		detectContent = content
 	}
 
-	// Now we can't use DetectBest or just results[0] because the result isn't stable - so we need a tie break
+	// Now we can't use DetectBest or just results[0] because the result isn't stable - so we need a tie-break
 	results, err := textDetector.DetectAll(detectContent)
 	if err != nil {
-		if err == chardet.NotDetectedError && len(setting.Repository.AnsiCharset) > 0 {
-			log.Debug("Using default AnsiCharset: %s", setting.Repository.AnsiCharset)
-			return setting.Repository.AnsiCharset, nil
-		}
-		return "", err
+		return util.IfZero(setting.Repository.AnsiCharset, "UTF-8"), err
 	}
 
 	topConfidence := results[0].Confidence
@@ -201,11 +211,9 @@ func DetectEncoding(content []byte) (string, error) {
 	}
 
 	// FIXME: to properly decouple this function the fallback ANSI charset should be passed as an argument
-	if topResult.Charset != "UTF-8" && len(setting.Repository.AnsiCharset) > 0 {
-		log.Debug("Using default AnsiCharset: %s", setting.Repository.AnsiCharset)
+	if topResult.Charset != "UTF-8" && setting.Repository.AnsiCharset != "" {
 		return setting.Repository.AnsiCharset, err
 	}
 
-	log.Debug("Detected encoding: %s", topResult.Charset)
-	return topResult.Charset, err
+	return topResult.Charset, nil
 }

modules/charset/charset_test.go

@@ -4,12 +4,12 @@
 package charset
 
 import (
-	"bytes"
 	"io"
 	"strings"
 	"testing"
 
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -47,12 +47,12 @@ func TestToUTF8(t *testing.T) {
 
 	res, err := ToUTF8([]byte{0x41, 0x42, 0x43}, ConvertOpts{})
 	assert.NoError(t, err)
-	assert.Equal(t, "ABC", res)
+	assert.Equal(t, "ABC", string(res))
 
 	// "áéíóú"
 	res, err = ToUTF8([]byte{0xc3, 0xa1, 0xc3, 0xa9, 0xc3, 0xad, 0xc3, 0xb3, 0xc3, 0xba}, ConvertOpts{})
 	assert.NoError(t, err)
-	assert.Equal(t, []byte{0xc3, 0xa1, 0xc3, 0xa9, 0xc3, 0xad, 0xc3, 0xb3, 0xc3, 0xba}, []byte(res))
+	assert.Equal(t, []byte{0xc3, 0xa1, 0xc3, 0xa9, 0xc3, 0xad, 0xc3, 0xb3, 0xc3, 0xba}, res)
 
 	// "áéíóú"
 	res, err = ToUTF8([]byte{
@@ -60,7 +60,7 @@ func TestToUTF8(t *testing.T) {
 		0xc3, 0xba,
 	}, ConvertOpts{})
 	assert.NoError(t, err)
-	assert.Equal(t, []byte{0xc3, 0xa1, 0xc3, 0xa9, 0xc3, 0xad, 0xc3, 0xb3, 0xc3, 0xba}, []byte(res))
+	assert.Equal(t, []byte{0xc3, 0xa1, 0xc3, 0xa9, 0xc3, 0xad, 0xc3, 0xb3, 0xc3, 0xba}, res)
 
 	res, err = ToUTF8([]byte{
 		0x48, 0x6F, 0x6C, 0x61, 0x2C, 0x20, 0x61, 0x73, 0xED, 0x20, 0x63,
@@ -96,12 +96,11 @@ func TestToUTF8(t *testing.T) {
 	assert.Equal(t, []byte{
 		0xE6, 0x97, 0xA5, 0xE5, 0xB1, 0x9E, 0xE7, 0xA7, 0x98, 0xE3,
 		0x81, 0x9E, 0xE3, 0x81, 0x97, 0xE3, 0x81, 0xA1, 0xE3, 0x82, 0x85, 0xE3, 0x80, 0x82,
-	},
-		[]byte(res))
+	}, res)
 
 	res, err = ToUTF8([]byte{0x00, 0x00, 0x00, 0x00}, ConvertOpts{})
 	assert.NoError(t, err)
-	assert.Equal(t, []byte{0x00, 0x00, 0x00, 0x00}, []byte(res))
+	assert.Equal(t, []byte{0x00, 0x00, 0x00, 0x00}, res)
 }
 
 func TestToUTF8WithFallback(t *testing.T) {
@@ -231,152 +230,42 @@ func TestDetectEncoding(t *testing.T) {
 	assert.Error(t, err)
 }
 
-func stringMustStartWith(t *testing.T, expected, value string) {
-	assert.Equal(t, expected, value[:len(expected)])
+func stringMustStartWith(t *testing.T, expected string, value []byte) {
+	assert.Equal(t, expected, string(value[:len(expected)]))
 }
 
-func stringMustEndWith(t *testing.T, expected, value string) {
-	assert.Equal(t, expected, value[len(value)-len(expected):])
+func stringMustEndWith(t *testing.T, expected string, value []byte) {
+	assert.Equal(t, expected, string(value[len(value)-len(expected):]))
 }
 
 func TestToUTF8WithFallbackReader(t *testing.T) {
 	resetDefaultCharsetsOrder()
+	test.MockVariableValue(&ToUTF8WithFallbackReaderPrefetchSize)
 
-	for testLen := range 2048 {
-		pattern := "    test { () }\n"
-		input := ""
-		for len(input) < testLen {
-			input += pattern
-		}
-		input = input[:testLen]
-		input += "// Выключаем"
-		rd := ToUTF8WithFallbackReader(bytes.NewReader([]byte(input)), ConvertOpts{})
+	block := "aá啊🤔"
+	runes := []rune(block)
+	assert.Len(t, string(runes[0]), 1)
+	assert.Len(t, string(runes[1]), 2)
+	assert.Len(t, string(runes[2]), 3)
+	assert.Len(t, string(runes[3]), 4)
+
+	content := strings.Repeat(block, 2)
+	for i := 1; i < len(content); i++ {
+		encoding, err := DetectEncoding([]byte(content[:i]))
+		assert.NoError(t, err)
+		assert.Equal(t, "UTF-8", encoding)
+
+		ToUTF8WithFallbackReaderPrefetchSize = i
+		rd := ToUTF8WithFallbackReader(strings.NewReader(content), ConvertOpts{})
 		r, _ := io.ReadAll(rd)
-		assert.Equalf(t, input, string(r), "testing string len=%d", testLen)
+		assert.Equal(t, content, string(r))
+	}
+	for _, r := range runes {
+		content = "abc abc " + string(r) + string(r) + string(r)
+		for i := 0; i < len(content); i++ {
+			encoding, err := DetectEncoding([]byte(content[:i]))
+			assert.NoError(t, err)
+			assert.Equal(t, "UTF-8", encoding)
+		}
 	}
-
-	truncatedOneByteExtension := failFastBytes
-	encoding, _ := DetectEncoding(truncatedOneByteExtension)
-	assert.Equal(t, "UTF-8", encoding)
-
-	truncatedTwoByteExtension := failFastBytes
-	truncatedTwoByteExtension[len(failFastBytes)-1] = 0x9b
-	truncatedTwoByteExtension[len(failFastBytes)-2] = 0xe2
-
-	encoding, _ = DetectEncoding(truncatedTwoByteExtension)
-	assert.Equal(t, "UTF-8", encoding)
-
-	truncatedThreeByteExtension := failFastBytes
-	truncatedThreeByteExtension[len(failFastBytes)-1] = 0x92
-	truncatedThreeByteExtension[len(failFastBytes)-2] = 0x9f
-	truncatedThreeByteExtension[len(failFastBytes)-3] = 0xf0
-
-	encoding, _ = DetectEncoding(truncatedThreeByteExtension)
-	assert.Equal(t, "UTF-8", encoding)
-}
-
-var failFastBytes = []byte{
-	0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x20, 0x6f, 0x72, 0x67, 0x2e, 0x61, 0x70, 0x61, 0x63, 0x68, 0x65, 0x2e, 0x74, 0x6f,
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-	0x20, 0x20, 0x20, 0x20, 0x2f, 0x2f, 0x20, 0xd0,
 }

routers/web/repo/editor.go

@@ -312,11 +312,13 @@ func EditFile(ctx *context.Context) {
 				ctx.ServerError("ReadAll", err)
 				return
 			}
+			var fileContent string
 			if content, err := charset.ToUTF8(buf, charset.ConvertOpts{KeepBOM: true}); err != nil {
-				ctx.Data["FileContent"] = string(buf)
+				fileContent = string(buf)
 			} else {
-				ctx.Data["FileContent"] = content
+				fileContent = string(content)
 			}
+			ctx.Data["FileContent"] = fileContent
 		}
 	}
 

services/gitdiff/gitdiff.go

@@ -1233,10 +1233,10 @@ func GetDiffForRender(ctx context.Context, repoLink string, gitRepo *git.Reposit
 		shouldFullFileHighlight := !setting.Git.DisableDiffHighlight && attrDiff.Value() == ""
 		if shouldFullFileHighlight {
 			if limitedContent.LeftContent != nil && limitedContent.LeftContent.buf.Len() < MaxDiffHighlightEntireFileSize {
-				diffFile.highlightedLeftLines = highlightCodeLines(diffFile, true /* left */, limitedContent.LeftContent.buf.String())
+				diffFile.highlightedLeftLines = highlightCodeLines(diffFile, true /* left */, limitedContent.LeftContent.buf.Bytes())
 			}
 			if limitedContent.RightContent != nil && limitedContent.RightContent.buf.Len() < MaxDiffHighlightEntireFileSize {
-				diffFile.highlightedRightLines = highlightCodeLines(diffFile, false /* right */, limitedContent.RightContent.buf.String())
+				diffFile.highlightedRightLines = highlightCodeLines(diffFile, false /* right */, limitedContent.RightContent.buf.Bytes())
 			}
 		}
 	}
@@ -1244,9 +1244,35 @@ func GetDiffForRender(ctx context.Context, repoLink string, gitRepo *git.Reposit
 	return diff, nil
 }
 
-func highlightCodeLines(diffFile *DiffFile, isLeft bool, content string) map[int]template.HTML {
+func splitHighlightLines(buf []byte) (ret [][]byte) {
+	lineCount := bytes.Count(buf, []byte("\n")) + 1
+	ret = make([][]byte, 0, lineCount)
+	nlTagClose := []byte("\n</")
+	for {
+		pos := bytes.IndexByte(buf, '\n')
+		if pos == -1 {
+			ret = append(ret, buf)
+			return ret
+		}
+		// Chroma highlighting output sometimes have "</span>" right after \n, sometimes before.
+		// * "<span>text\n</span>"
+		// * "<span>text</span>\n"
+		if bytes.HasPrefix(buf[pos:], nlTagClose) {
+			pos1 := bytes.IndexByte(buf[pos:], '>')
+			if pos1 != -1 {
+				pos += pos1
+			}
+		}
+		ret = append(ret, buf[:pos+1])
+		buf = buf[pos+1:]
+	}
+}
+
+func highlightCodeLines(diffFile *DiffFile, isLeft bool, rawContent []byte) map[int]template.HTML {
+	contentUTF8, _ := charset.ToUTF8(rawContent, charset.ConvertOpts{})
+	content := util.UnsafeBytesToString(contentUTF8)
 	highlightedNewContent, _ := highlight.Code(diffFile.Name, diffFile.Language, content)
-	splitLines := strings.Split(string(highlightedNewContent), "\n")
+	splitLines := splitHighlightLines([]byte(highlightedNewContent))
 	lines := make(map[int]template.HTML, len(splitLines))
 	// only save the highlighted lines we need, but not the whole file, to save memory
 	for _, sec := range diffFile.Sections {

services/gitdiff/gitdiff_test.go

@@ -5,6 +5,7 @@
 package gitdiff
 
 import (
+	"html/template"
 	"strconv"
 	"strings"
 	"testing"
@@ -640,3 +641,41 @@ func TestNoCrashes(t *testing.T) {
 		ParsePatch(t.Context(), setting.Git.MaxGitDiffLines, setting.Git.MaxGitDiffLineCharacters, setting.Git.MaxGitDiffFiles, strings.NewReader(testcase.gitdiff), "")
 	}
 }
+
+func TestHighlightCodeLines(t *testing.T) {
+	t.Run("CharsetDetecting", func(t *testing.T) {
+		diffFile := &DiffFile{
+			Name:     "a.c",
+			Language: "c",
+			Sections: []*DiffSection{
+				{
+					Lines: []*DiffLine{{LeftIdx: 1}},
+				},
+			},
+		}
+		ret := highlightCodeLines(diffFile, true, []byte("// abc\xcc def\xcd")) // ISO-8859-1 bytes
+		assert.Equal(t, "<span class=\"c1\">// abcÌ defÍ\n</span>", string(ret[0]))
+	})
+
+	t.Run("LeftLines", func(t *testing.T) {
+		diffFile := &DiffFile{
+			Name:     "a.c",
+			Language: "c",
+			Sections: []*DiffSection{
+				{
+					Lines: []*DiffLine{
+						{LeftIdx: 1},
+						{LeftIdx: 2},
+						{LeftIdx: 3},
+					},
+				},
+			},
+		}
+		const nl = "\n"
+		ret := highlightCodeLines(diffFile, true, []byte("a\nb\n"))
+		assert.Equal(t, map[int]template.HTML{
+			0: `<span class="n">a</span>` + nl,
+			1: `<span class="n">b</span>`,
+		}, ret)
+	})
+}