filetype - infer file types checking the magic numbers signature in Go

filetype

Small and dependency free Go package to infer file and MIME type checking the magic numbers signature.

For SVG file type checking, see go-is-svg package.

Features

  • Provides file extension and proper MIME type
  • File discovery by extension or MIME type
  • File discovery by class (image, video, audio...)
  • Provides a bunch of helpers and file matching shortcuts
  • Simple and semantic API
  • Only first 262 bytes representing the max file header is required, so you can just
  • Dependency free (just Go code, no C compilation needed)
  • Cross-platform file recognition

Installation

go get github.com/h2non/filetype

API

See Godoc reference.

Subpackages

Examples

Simple file type checking

package main

import (
  "fmt"
  "io/ioutil"

  "github.com/h2non/filetype"
)

func main() {
  buf, _ := ioutil.ReadFile("sample.jpg")

  kind, unknown := filetype.Match(buf)
  if unknown != nil {
    fmt.Printf("Unknown: %s", unknown)
    return
  }

  fmt.Printf("File type: %s. MIME: %s\n", kind.Extension, kind.MIME.Value)
}

Check type class

package main

import (
  "fmt"
  "io/ioutil"

  "github.com/h2non/filetype"
)

func main() {
  buf, _ := ioutil.ReadFile("sample.jpg")

  if filetype.IsImage(buf) {
    fmt.Println("File is an image")
  } else {
    fmt.Println("Not an image")
  }
}

Supported type

package main

import (
  "fmt"

  "github.com/h2non/filetype"
)

func main() {
  // Check if file is supported by extension
  if filetype.IsSupported("jpg") {
    fmt.Println("Extension supported")
  } else {
    fmt.Println("Extension not supported")
  }

  // Check if file is supported by extension
  if filetype.IsMIMESupported("image/jpeg") {
    fmt.Println("MIME type supported")
  } else {
    fmt.Println("MIME type not supported")
  }
}

File header

package main

import (
  "fmt"
  "io/ioutil"
  
  "github.com/h2non/filetype"
)

func main() {
  // Open a file descriptor
  file, _ := os.Open("movie.mp4")

  // We only have to pass the file header = first 261 bytes
  head := make([]byte, 261)
  file.Read(head)

  if filetype.IsImage(head) {
    fmt.Println("File is an image")
  } else {
    fmt.Println("Not an image")
  }
}

Add additional file type matchers

package main

import (
  "fmt"
  
  "github.com/h2non/filetype"
)

var fooType = filetype.NewType("foo", "foo/foo")

func fooMatcher(buf []byte) bool {
  return len(buf) > 1 && buf[0] == 0x01 && buf[1] == 0x02
}

func main() {
  // Register the new matcher and its type
  filetype.AddMatcher(fooType, fooMatcher)

  // Check if the new type is supported by extension
  if filetype.IsSupported("foo") {
    fmt.Println("New supported type: foo")
  }

  // Check if the new type is supported by MIME
  if filetype.IsMIMESupported("foo/foo") {
    fmt.Println("New supported MIME type: foo/foo")
  }

  // Try to match the file
  fooFile := []byte{0x01, 0x02}
  kind, _ := filetype.Match(fooFile)
  if kind == filetype.Unknown {
    fmt.Println("Unknown file type")
  } else {
    fmt.Printf("File type matched: %s\n", kind.Extension)
  }
}

Supported types

Image

  • jpg - image/jpeg
  • png - image/png
  • gif - image/gif
  • webp - image/webp
  • cr2 - image/x-canon-cr2
  • tif - image/tiff
  • bmp - image/bmp
  • jxr - image/vnd.ms-photo
  • psd - image/vnd.adobe.photoshop
  • ico - image/x-icon

Video

  • mp4 - video/mp4
  • m4v - video/x-m4v
  • mkv - video/x-matroska
  • webm - video/webm
  • mov - video/quicktime
  • avi - video/x-msvideo
  • wmv - video/x-ms-wmv
  • mpg - video/mpeg
  • flv - video/x-flv

Audio

  • mid - audio/midi
  • mp3 - audio/mpeg
  • m4a - audio/m4a
  • ogg - audio/ogg
  • flac - audio/x-flac
  • wav - audio/x-wav
  • amr - audio/amr
  • aac - audio/aac

Archive

  • epub - application/epub+zip
  • zip - application/zip
  • tar - application/x-tar
  • rar - application/x-rar-compressed
  • gz - application/gzip
  • bz2 - application/x-bzip2
  • 7z - application/x-7z-compressed
  • xz - application/x-xz
  • pdf - application/pdf
  • exe - application/x-msdownload
  • swf - application/x-shockwave-flash
  • rtf - application/rtf
  • eot - application/octet-stream
  • ps - application/postscript
  • sqlite - application/x-sqlite3
  • nes - application/x-nintendo-nes-rom
  • crx - application/x-google-chrome-extension
  • cab - application/vnd.ms-cab-compressed
  • deb - application/x-deb
  • ar - application/x-unix-archive
  • Z - application/x-compress
  • lz - application/x-lzip
  • rpm - application/x-rpm
  • elf - application/x-executable

Documents

  • doc - application/msword
  • docx - application/vnd.openxmlformats-officedocument.wordprocessingml.document
  • xls - application/vnd.ms-excel
  • xlsx - application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
  • ppt - application/vnd.ms-powerpoint
  • pptx - application/vnd.openxmlformats-officedocument.presentationml.presentation

Font

  • woff - application/font-woff
  • woff2 - application/font-woff
  • ttf - application/font-sfnt
  • otf - application/font-sfnt

Benchmarks

Measured using real files .

Environment: OSX x64 i7 2.7 Ghz

BenchmarkMatchTar-8    1000000        1083 ns/op
BenchmarkMatchZip-8    1000000        1162 ns/op
BenchmarkMatchJpeg-8   1000000        1280 ns/op
BenchmarkMatchGif-8    1000000        1315 ns/op
BenchmarkMatchPng-8    1000000        1121 ns/op

License

MIT - Tomas Aparicio

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