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