mimemagic
Powerful and versatile MIME sniffing package using pre-compiled glob patterns, magic number signatures, xml document
namespaces, and tree magic for mounted volumes, generated from the XDG shared-mime-info database.
Features
- All in native go, no outside dependencies/C library bindings
- 1003 MIME types, with a description, an acronym (where available), common aliases, extensions, icons, and
subclasses - 493 magic signature tests (comprising of 1147 individual patterns), featuring range searches and bit masks, as per
the xdg specification - 1099 glob patterns, for filename-based matching
- 11 Tree Magic signatures and 28 XML namespace/local name pairs, offered for completeness' sake.
- Included is the xml file parser to generate your own MIME definitions
- Also included is a CLI based on this library that is fully featured and blazing-fast, beating the native 'file'
and KDE's 'kmimetypefinder' in performance - Cross-platform support
Installation
The library:
go get github.com/zRedShift/mimemagic
The CLI:
go get github.com/zRedShift/mimemagic/cmd/mimemagic
API
See the Godoc reference, and cmd/mimemagic for an example
implementation.
Usage
The library:
package main
import (
"fmt"
"github.com/zRedShift/mimemagic"
"strings"
)
func main() {
// Ignoring Read errors that might arise
mimeType, _ := mimemagic.MatchFilePath("sample.svgz", -1)
// image/svg+xml-compressed
fmt.Println(mimeType.MediaType())
// compressed SVG image
fmt.Println(mimeType.Comment)
// SVG (Scalable Vector Graphics)
fmt.Printf("%s (%s)\n", mimeType.Acronym, mimeType.ExpandedAcronym)
// application/gzip
fmt.Println(strings.Join(mimeType.SubClassOf, ", "))
// .svgz
fmt.Println(strings.Join(mimeType.Extensions, ", "))
// This is an image.
switch mimeType.Media {
case "image":
fmt.Println("This is an image.")
case "video":
fmt.Println("This is a video file.")
case "audio":
fmt.Println("This is an audio file.")
case "application":
fmt.Println("This is an application.")
default:
fmt.Printf("This is a(n) %s.", mimeType.Media)
}
// true
fmt.Println(mimeType.IsExtension(".svgz"))
}
The CLI:
Usage: mimemagic [options] <file> ...
Determines the MIME type of the given file(s).
Options:
-c Determine the MIME type of the file(s) using only its content.
-f Determine the MIME type of the file(s) using only the file name. Does
not check for the file's existence. The -c
flag takes precedence.
-i Output the MIME type in a human readable format.
-l int
The number of bytes from the beginning of the file mimemagic will
examine. Reads the entire file if set to a negative value. By default
mimemagic will only read the first 512 from stdin, however setting this
flag to a non-default negative value will override this. (default -1)
-t Determine the MIME type of the directory/mounted volume using tree
magic. Can't be used in conjunction with with -c, -f or -x.
-x Determine the MIME type of the xml file(s) using the local names and
namespaces within. Can't be used in conjunction with -c, -f or -t.
Arguments:
file
The file(s) to test. '-' to read from stdin. If '-' is set, all other
inputs will be ignored.
Examples:
$ mimemagic -c sample.svgz
application/gzip
$ mimemagic *.svg*
Olympic_rings_with_transparent_rims.svg: image/svg+xml
Piano.svg.png: image/png
RAID_5.svg: image/svg+xml
sample.svgz: image/svg+xml-compressed
$ cat /dev/urandom, mimemagic -
application/octet-stream
$ ls software; mimemagic -i -t software/
autorun
UNIX software
Benchmarks
See Benchmarks. For Match(), the average across
over 400 completely different files (representing a unique MIME type each) is 13 ± 7 μs/op. For MatchGlob() it's 900
± 200 ns/op, and for 12 ± 7 μs/op MatchMagic().