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