Small IDA .dif patcher with PEP 8 improvment. Original Source: https://stalkr.net/files/ida/idadif.py

idadif.py

#!/usr/bin/env python
# Small IDA .dif patcher
import re
from sys import argv, exit


def patch(file, dif, revert=False):
    code = open(file, 'rb').read()
    dif = open(dif, 'r').read()
    m = re.findall('([0-9a-fA-F]+): ([0-9a-fA-F]+) ([0-9a-fA-F]+)', dif)
    for offset, orig, new in m:
        o, orig, new = int(offset, 16), orig.decode('hex'), new.decode('hex')
        if revert:
            if code[o] == new:
                code = code[:o] + orig + code[o + 1:]
            else:
                raise Exception(
                    "patched byte at %s is not %02X" % (offset, ord(new)))
        else:
            if code[o] == orig:
                code = code[:o] + new + code[o + 1:]
            else:
                raise Exception(
                    "original byte at %s is not %02X" % (offset, ord(orig)))
    open(file, 'wb').write(code)


def main():
    if len(argv) < 3:
        print("Usage: %s <binary> <IDA.dif file> [revert]" % (argv[0]))
        print("Applies given IDA .dif file to patch binary; use revert to revert patch.")
        exit(0)

    file, dif, revert = argv[1], argv[2], False
    if len(argv) > 3:
        revert = True
        print("Reverting patch %r on file %r" % (dif, file))
    else:
        print("Patching file %r with %r" % (file, dif))

    try:
        patch(file, dif, revert)
        print("Done")
    except Exception as e:
        print("Error: %s" % str(e))
        exit(1)

if __name__ == "__main__":
    main()