It seems that an error occurs here and it recognizes the .gz

If you want to get extension directly from libmagic: <div class="highlight highlig

Different extension compared to the `file` command about mime HOT 2 OPEN

hey-red commented on May 27, 2024

Different extension compared to the `file` command

from mime.

Comments (2)

hey-red commented on May 27, 2024

If you want to get extension directly from libmagic:

using var magic = new Magic(MagicOpenFlags.MAGIC_EXTENSION);
var result = magic.Read(@"/path/to/gzip.gz"); // from file
Console.WriteLine(result); // -> gz/tgz/tpz/ipk/vbox-extpack/svgz/blend/dia/gnucash/rdata/xoj

However for this file it doesn't work when the magic_buffer method is used:

byte[] buf = File.ReadAllBytes(@"/path/to/gzip.gz");
using var magic = new Magic(MagicOpenFlags.MAGIC_EXTENSION);
var result = magic.Read(buf, buf.Length);
Console.WriteLine(result); // -> "???"

I have no idea why we have different behaviour..
But I think you can update MimeTypesMap dict, before you get results from MimeGuesser:
MimeTypesMap.AddOrUpdate("application/gzip", "gz");
or create your own dictionary with mime<->extensions mapping.

from mime.

alireza-rezaee commented on May 27, 2024

byte[] buf = File.ReadAllBytes(@"/path/to/gzip.gz");
using var magic = new Magic(MagicOpenFlags.MAGIC_EXTENSION);
var result = magic.Read(buf, buf.Length);
Console.WriteLine(result); // -> "???"

This difference behavior is strange, but it is OK with this very similar gzip-name.gz file:

$ xxd gzip.gz
00000000: 1f8b 0800 ae86 e15b 0203 0300 0000 0000  .......[........
00000010: 0000 0000                                ....

$ xxd gzip-name.gz
00000000: 1f8b 0808 ae86 e15b 0203 6e00 0300 0000  .......[..n.....
00000010: 0000 0000 0000

// gzip-name.gz
bytes[] fileBytes =
[
    0x1f, 0x8b, 0x08, 0x08, 0xae, 0x86, 0xe1, 0x5b, 0x02, 0x03, 0x6e, 0x00, 0x03, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00
];
using var magic = new Magic(MagicOpenFlags.MAGIC_EXTENSION);
magic.Read(fileBytes, fileBytes.Length) // -> "gz/tgz/tpz/zabw/svgz/adz/kmy/xcfgz"