Terrible script to dump CPython bytecode from a .pyc file

load_pyc.py

"""
Usage:

    python3 -i load_pyc.py path/to/file.pyc

"""

import dis
import importlib.util
import marshal
import struct
import sys

INTERPRETER_MAGIC_NUMBER = importlib.util.MAGIC_NUMBER


def read_u32le(f):
    """Read unsigned 32-bit int (little endian)."""
    return struct.unpack("<I", f.read(4))[0]


def decode_u16le(b):
    """Read unsigned 16-bit int (little endian)."""
    return struct.unpack("<H", b)[0]


with open(sys.argv[1], "rb") as bytecode_file:
    magic_number = bytecode_file.read(4)
    header = read_u32le(bytecode_file)
    if header == 0:
        print("Timestamp .pyc")
        time_stamp = read_u32le(bytecode_file)
        file_size = read_u32le(bytecode_file)
    else:
        print("Hash pyc: idk how to deal with this")
        print(magic_number, header)

    # load the bytecode
    bytecode = marshal.load(bytecode_file)

version = decode_u16le(magic_number[:2])

if magic_number == INTERPRETER_MAGIC_NUMBER:
    print(f"versions match: {version}")
else:
    print("Python version does not match :(")
    print(
        "Consult: https://github.com/python/cpython/blob/main/Lib/importlib/_bootstrap_external.py"
    )
    print(f"for a list that matches version: {version}")