Detect whether a Windows exe or dll is a 32 or 64bit executable.

petype.py

"""Detect whether a Windows exe or dll is a 32 or 64bit executable.

Port of the perl script given by Paul Dixon on a Stack Overflow answer [1]_

.. [1] http://stackoverflow.com/a/495305/40056
"""

import sys
import os
from struct import unpack


def detect_petype(fpath):
    with open(fpath, 'rb') as f:
        dos_header = f.read(64)
        magic, _, offset = unpack('2s58sl', dos_header)
        if magic.decode('ascii') != 'MZ':
            raise ValueError("The file {} is not an executable".format(fpath))

        f.seek(offset)
        pe_header = f.read(6)
        sig, _, machine = unpack('2s2sH', pe_header)

        if sig.decode('ascii') != 'PE':
            raise ValueError("The file {} is not a PE executable ".format(fpath))

        if machine == 0x014c:
            return 'i386'
        elif machine == 0x0200:
            return 'IA64'
        elif machine == 0x8664:
            return 'AMD64'
        else:
            return 'unknown machine type: {}'.format(machine)


def main():
    if len(sys.argv) != 2:
        print("usage: petype.py path/to/exefile")
        return 1
    fpath = sys.argv[1]
    if os.path.exists(fpath):
        try:
            print(detect_petype(fpath))
            return 0
        except (ValueError, IOError) as e:
            print("Failure during parsing of the exe header. Reason:".format(e.args))
            return 1
    else:
        return 1

if __name__ == '__main__':
    sys.exit(main())