#!/usr/bin/env python3
# Copyright (c) 2023 Luke Dashjr
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.

import sys

with open(sys.argv[1], "r+b") as dmg:
    # Ensure HFS+ header is where we expect it
    dmg.seek(0x10400)
    assert dmg.read(4) == b'\x48\x2b\0\x04'

    # Set Finder info to open directory ID 2 when mounted
    dmg.seek(0x10458)
    dmg.write(b'\0\0\0\x02')