Applies IDA Patches to Binaries

patch.py

import argparse
import fileinput
import re
import binascii
import struct

unhex   = binascii.unhexlify
u32     = lambda x: struct.unpack('>L', x)[0]
hexa    = r'[0-9A-F]'
pattern = r'(%s{8}): (%s{2}) (%s{2})' % (hexa, hexa, hexa)
regex   = re.compile(pattern)

def apply_patch(data, patch):
    """Applies a patch to data

    Args:
        data:  List of bytes to patch
        patch: File to read the patch data from, in the format generated
               by IDA Pro.

    Returns:
        Patched list of bytes
    """

    for line in patch.readlines():
        match = regex.match(line)

        if not match:
            continue

        offset, old, new = match.groups(line)
        offset = u32(unhex(offset))
        old    = unhex(old)
        new    = unhex(new)

        print "%08x: %r %r" % (offset, old, new)

        cur    = data[offset]
        if cur != old:
            print "ERROR! Offset %x doesn't match (expected %r, got %r)" % (offset, old, cur)
            return None

        data[offset] = new

    return data

if __name__ == '__main__':
    p = argparse.ArgumentParser()

    p.add_argument('--input', type=argparse.FileType('rb'))
    p.add_argument('--output', type=argparse.FileType('wb'))
    p.add_argument('patches', type=argparse.FileType('rb'), nargs='+')
    args = p.parse_args()

    data = list(args.input.read())
    for patchfile in args.patches:
        data = apply_patch(data, patchfile)
    args.output.write(''.join(data))