mantyr/filetype

Small Go package to infer the file type checking its magic numbers signature

filetype

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

Features

• Supports a wide range of file types
• 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
• Pluggable: add custom new types and matchers
• Simple and semantic API
• Blazing fast, even processing large files
• Only first 261 bytes representing the max file header is required, so you can just pass a slice

Installation

go get gopkg.in/h2non/filetype.v0

API

See Godoc reference.

Subpackages

• gopkg.in/h2non/filetype.v0/types
• gopkg.in/h2non/filetype.v0/matchers

Examples

Simple file type checking

package main

import (
  "fmt"
  "gopkg.in/h2non/filetype.v0"
  "io/ioutil"
)

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

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

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

Check type class

package main

import (
  "fmt"
  "gopkg.in/h2non/filetype.v0"
  "io/ioutil"
)

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"
  "gopkg.in/h2non/filetype.v0"
)

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"
  "gopkg.in/h2non/filetype.v0"
  "io/ioutil"
)

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

  // We only have to pass the file header = first 261 bytes
  head := buf[:261]

  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"
  "gopkg.in/h2non/filetype.v0"
)

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

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

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