Looking for determine file type from the magic number

Question

It is possible to determine the file type from the magic number of file?

If I've understood, the magic number can have different size, maybe a reference dictionary or something like a library could help me?

XP SP3, it will an affect my program?I mean, I want it work on linux too — CheapD AKA Ju, Aug 29 '13 at 08:44
Only because I wasn't going to suggest Linux tools if you were on Windows. — ams, Aug 29 '13 at 09:13
Possible duplicate of [How to get magic number of a binary file](https://stackoverflow.com/q/2147484/608639). — jww, Jun 14 '18 at 00:23

score 1 · Answer 1 · answered Aug 29 '13 at 08:47

1

it is possible to determine the file type from the magic number of file

yes you can ,because each file format has different magic number.

for example FFD8 for .jpg files

See here Magic Numbers in Files

answered Aug 29 '13 at 08:47

Gangadhar

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TheCodeArtist · Answer 2 · 2013-08-29T08:52:40.713

0

The file command on Linux does precisely that. Study its internals to see how it identifies files using their magic-numbers(signature bytes). The complete source-code is available at darwinsys.com/file.

The following 2 lists are the most comprehensive ones with file-types and their magic-numbers:
- File Signature Table
- Linux Magic Numbers

edited Aug 29 '13 at 08:52

answered Aug 29 '13 at 08:47

TheCodeArtist

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Thank you, simple and effective, Signature table is exactly what I was looking for – CheapD AKA Ju Aug 29 '13 at 08:56

score 0 · Answer 3 · answered May 23 '15 at 21:57

0

JmimeMagic is a java library for such

answered May 23 '15 at 21:57

Monish Sen

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score 0 · Answer 4 · answered Apr 30 '19 at 19:23

Use libmagic (apt-get install libmagic-dev on Ubuntu systems).

Example below uses the default magic database to query the file passed on the command line. (Essentially an implementation of the file command. See man libmagic for more details/functions.

#include <iostream>
#include <magic.h>
#include <cassert>
int main(int argc, char **argv) {
    if (argc == 1) {
            std::cerr << "Usage "  << argv[0] << " [filename]" << std::endl;
            return -1;
    }
    const char * fname = argv[1];
    magic_t cookie = magic_open(0);
    assert (cookie !=nullptr);
    int rc = magic_load(cookie, nullptr);
    assert(rc == 0);
    auto f=  magic_file(cookie, fname);
    if (f ==nullptr) {
        std::cerr << magic_error(cookie) << std::endl;
    } else {
        std::cout << fname << ' ' << f << std::endl;
    }

}

Looking for determine file type from the magic number

4 Answers4