#!/usr/bin/env python3
import argparse, struct, sys

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

    parser.add_argument('file', help='input file')
    args = parser.parse_args()

    with open(args.file, 'r+b') as f:
        magic = struct.unpack('>I', f.read(4))[0]
        if magic != 0x7F454C46:
            print('Error: Not an ELF file')
            sys.exit(1)

        f.seek(36)
        flags = struct.unpack('>I', f.read(4))[0]
        if flags & 0xF0000000 != 0x20000000: # test for mips3
            print('Error: Architecture not mips3')
            sys.exit(1)

        flags |= 0x00001000 # set EF_MIPS_ABI_O32
        f.seek(36)
        f.write(struct.pack('>I', flags))
