99 lines
2.8 KiB
Go
99 lines
2.8 KiB
Go
// Copyright 2021 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 typesniffer
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"net/http"
|
|
"regexp"
|
|
"strings"
|
|
|
|
"code.gitea.io/gitea/modules/util"
|
|
)
|
|
|
|
// Use at most this many bytes to determine Content Type.
|
|
const sniffLen = 1024
|
|
|
|
// SvgMimeType MIME type of SVG images.
|
|
const SvgMimeType = "image/svg+xml"
|
|
|
|
var svgTagRegex = regexp.MustCompile(`(?si)\A\s*(?:(<!--.*?-->|<!DOCTYPE\s+svg([\s:]+.*?>|>))\s*)*<svg[\s>\/]`)
|
|
var svgTagInXMLRegex = regexp.MustCompile(`(?si)\A<\?xml\b.*?\?>\s*(?:(<!--.*?-->|<!DOCTYPE\s+svg([\s:]+.*?>|>))\s*)*<svg[\s>\/]`)
|
|
|
|
// SniffedType contains information about a blobs type.
|
|
type SniffedType struct {
|
|
contentType string
|
|
}
|
|
|
|
// IsText etects if content format is plain text.
|
|
func (ct SniffedType) IsText() bool {
|
|
return strings.Contains(ct.contentType, "text/")
|
|
}
|
|
|
|
// IsImage detects if data is an image format
|
|
func (ct SniffedType) IsImage() bool {
|
|
return strings.Contains(ct.contentType, "image/")
|
|
}
|
|
|
|
// IsSvgImage detects if data is an SVG image format
|
|
func (ct SniffedType) IsSvgImage() bool {
|
|
return strings.Contains(ct.contentType, SvgMimeType)
|
|
}
|
|
|
|
// IsPDF detects if data is a PDF format
|
|
func (ct SniffedType) IsPDF() bool {
|
|
return strings.Contains(ct.contentType, "application/pdf")
|
|
}
|
|
|
|
// IsVideo detects if data is an video format
|
|
func (ct SniffedType) IsVideo() bool {
|
|
return strings.Contains(ct.contentType, "video/")
|
|
}
|
|
|
|
// IsAudio detects if data is an video format
|
|
func (ct SniffedType) IsAudio() bool {
|
|
return strings.Contains(ct.contentType, "audio/")
|
|
}
|
|
|
|
// IsRepresentableAsText returns true if file content can be represented as
|
|
// plain text or is empty.
|
|
func (ct SniffedType) IsRepresentableAsText() bool {
|
|
return ct.IsText() || ct.IsSvgImage()
|
|
}
|
|
|
|
// DetectContentType extends http.DetectContentType with more content types. Defaults to text/unknown if input is empty.
|
|
func DetectContentType(data []byte) SniffedType {
|
|
if len(data) == 0 {
|
|
return SniffedType{"text/unknown"}
|
|
}
|
|
|
|
ct := http.DetectContentType(data)
|
|
|
|
if len(data) > sniffLen {
|
|
data = data[:sniffLen]
|
|
}
|
|
|
|
if (strings.Contains(ct, "text/plain") || strings.Contains(ct, "text/html")) && svgTagRegex.Match(data) ||
|
|
strings.Contains(ct, "text/xml") && svgTagInXMLRegex.Match(data) {
|
|
// SVG is unsupported. https://github.com/golang/go/issues/15888
|
|
ct = SvgMimeType
|
|
}
|
|
|
|
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
|
|
}
|