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Fast, dependency-free Go package to infer binary file types based on the magic numbers header signature

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filetype GoDoc Go Version

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. Python port: filetype.py.

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 262 bytes representing the max file header is required, so you can just pass a slice
  • 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, _ := filetype.Match(buf)
  if kind == filetype.Unknown {
    fmt.Println("Unknown file type")
    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"
  "os"

  "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
  • heif - image/heif
  • jxr - image/vnd.ms-photo
  • psd - image/vnd.adobe.photoshop
  • ico - image/vnd.microsoft.icon
  • dwg - image/vnd.dwg
  • avif - image/avif

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
  • 3gp - video/3gpp

Audio

  • mid - audio/midi
  • mp3 - audio/mpeg
  • m4a - audio/mp4
  • ogg - audio/ogg
  • flac - audio/x-flac
  • wav - audio/x-wav
  • amr - audio/amr
  • aac - audio/aac
  • aiff - audio/x-aiff

Archive

  • epub - application/epub+zip
  • zip - application/zip
  • tar - application/x-tar
  • rar - application/vnd.rar
  • gz - application/gzip
  • bz2 - application/x-bzip2
  • 7z - application/x-7z-compressed
  • xz - application/x-xz
  • zstd - application/zstd
  • pdf - application/pdf
  • exe - application/vnd.microsoft.portable-executable
  • swf - application/x-shockwave-flash
  • rtf - application/rtf
  • iso - application/x-iso9660-image
  • eot - application/octet-stream
  • ps - application/postscript
  • sqlite - application/vnd.sqlite3
  • nes - application/x-nintendo-nes-rom
  • crx - application/x-google-chrome-extension
  • cab - application/vnd.ms-cab-compressed
  • deb - application/vnd.debian.binary-package
  • ar - application/x-unix-archive
  • Z - application/x-compress
  • lz - application/x-lzip
  • rpm - application/x-rpm
  • elf - application/x-executable
  • dcm - application/dicom

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

Application

  • wasm - application/wasm
  • dex - application/vnd.android.dex
  • dey - application/vnd.android.dey

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