refactor DetectContentTypeFromReader

Author: wxiaoguang

modules/git/blob.go

@@ -22,17 +22,22 @@ func (b *Blob) Name() string {
 	return b.name
 }
 
-// GetBlobContent Gets the limited content of the blob as raw text
-func (b *Blob) GetBlobContent(limit int64) (string, error) {
+// GetBlobBytes Gets the limited content of the blob
+func (b *Blob) GetBlobBytes(limit int64) ([]byte, error) {
 	if limit <= 0 {
-		return "", nil
+		return nil, nil
 	}
 	dataRc, err := b.DataAsync()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer dataRc.Close()
-	buf, err := util.ReadWithLimit(dataRc, int(limit))
+	return util.ReadWithLimit(dataRc, int(limit))
+}
+
+// GetBlobContent Gets the limited content of the blob as raw text
+func (b *Blob) GetBlobContent(limit int64) (string, error) {
+	buf, err := b.GetBlobBytes(limit)
 	return string(buf), err
 }
 
@@ -99,11 +104,9 @@ loop:
 
 // GuessContentType guesses the content type of the blob.
 func (b *Blob) GuessContentType() (typesniffer.SniffedType, error) {
-	r, err := b.DataAsync()
+	buf, err := b.GetBlobBytes(typesniffer.SniffContentSize)
 	if err != nil {
 		return typesniffer.SniffedType{}, err
 	}
-	defer r.Close()
-
-	return typesniffer.DetectContentTypeFromReader(r)
+	return typesniffer.DetectContentType(buf), nil
 }

modules/typesniffer/typesniffer.go

@@ -6,19 +6,14 @@ package typesniffer
 import (
 	"bytes"
 	"encoding/binary"
-	"fmt"
-	"io"
 	"net/http"
 	"regexp"
 	"slices"
 	"strings"
 	"sync"
-
-	"code.gitea.io/gitea/modules/util"
 )
 
-// Use at most this many bytes to determine Content Type.
-const sniffLen = 1024
+const SniffContentSize = 1024
 
 const (
 	MimeTypeImageSvg  = "image/svg+xml"
@@ -42,7 +37,7 @@ type SniffedType struct {
 	contentType string
 }
 
-// IsText detects if the content format is plain text.
+// IsText detects if the content format is text family, including text/plain, text/html, text/css, etc.
 func (ct SniffedType) IsText() bool {
 	return strings.Contains(ct.contentType, "text/")
 }
@@ -66,12 +61,12 @@ func (ct SniffedType) IsPDF() bool {
 	return strings.Contains(ct.contentType, "application/pdf")
 }
 
-// IsVideo detects if data is an video format
+// IsVideo detects if data is a video format
 func (ct SniffedType) IsVideo() bool {
 	return strings.Contains(ct.contentType, "video/")
 }
 
-// IsAudio detects if data is an video format
+// IsAudio detects if data is a video format
 func (ct SniffedType) IsAudio() bool {
 	return strings.Contains(ct.contentType, "audio/")
 }
@@ -87,10 +82,6 @@ func (ct SniffedType) IsBrowsableBinaryType() bool {
 	return ct.IsImage() || ct.IsSvgImage() || ct.IsPDF() || ct.IsVideo() || ct.IsAudio()
 }
 
-func (ct SniffedType) IsApplicationOctetStream() bool {
-	return ct.contentType == "application/octet-stream"
-}
-
 // GetMimeType returns the mime type
 func (ct SniffedType) GetMimeType() string {
 	return strings.SplitN(ct.contentType, ";", 2)[0]
@@ -116,16 +107,16 @@ func detectFileTypeBox(data []byte) (brands []string, found bool) {
 	return brands, true
 }
 
-// DetectContentType extends http.DetectContentType with more content types. Defaults to text/unknown if input is empty.
+// DetectContentType extends http.DetectContentType with more content types. Defaults to text/plain if input is empty.
 func DetectContentType(data []byte) SniffedType {
 	if len(data) == 0 {
-		return SniffedType{"text/unknown"}
+		return SniffedType{"text/plain"}
 	}
 
 	ct := http.DetectContentType(data)
 
-	if len(data) > sniffLen {
-		data = data[:sniffLen]
+	if len(data) > SniffContentSize {
+		data = data[:SniffContentSize]
 	}
 
 	vars := globalVars()
@@ -143,7 +134,7 @@ func DetectContentType(data []byte) SniffedType {
 
 	if strings.HasPrefix(ct, "audio/") && bytes.HasPrefix(data, []byte("ID3")) {
 		// The MP3 detection is quite inaccurate, any content with "ID3" prefix will result in "audio/mpeg".
-		// So remove the "ID3" prefix and detect again, if result is text, then it must be text content.
+		// So remove the "ID3" prefix and detect again, then if the result is "text", it must be text content.
 		// This works especially because audio files contain many unprintable/invalid characters like `0x00`
 		ct2 := http.DetectContentType(data[3:])
 		if strings.HasPrefix(ct2, "text/") {
@@ -169,15 +160,3 @@ func DetectContentType(data []byte) SniffedType {
 	}
 	return SniffedType{ct}
 }
-
-// DetectContentTypeFromReader guesses the content type contained in the reader.
-func DetectContentTypeFromReader(r io.Reader) (SniffedType, error) {
-	buf := make([]byte, sniffLen)
-	n, err := util.ReadAtMost(r, buf)
-	if err != nil {
-		return SniffedType{}, fmt.Errorf("DetectContentTypeFromReader io error: %w", err)
-	}
-	buf = buf[:n]
-
-	return DetectContentType(buf), nil
-}

modules/typesniffer/typesniffer_test.go

@@ -17,7 +17,7 @@ func TestDetectContentTypeLongerThanSniffLen(t *testing.T) {
 	// Pre-condition: Shorter than sniffLen detects SVG.
 	assert.Equal(t, "image/svg+xml", DetectContentType([]byte(`<!-- Comment --><svg></svg>`)).contentType)
 	// Longer than sniffLen detects something else.
-	assert.NotEqual(t, "image/svg+xml", DetectContentType([]byte(`<!-- `+strings.Repeat("x", sniffLen)+` --><svg></svg>`)).contentType)
+	assert.NotEqual(t, "image/svg+xml", DetectContentType([]byte(`<!-- `+strings.Repeat("x", SniffContentSize)+` --><svg></svg>`)).contentType)
 }
 
 func TestIsTextFile(t *testing.T) {