revng-revng/scripts/compile-time-constants.py

#!/usr/bin/env python3
#
# This file is distributed under the MIT License. See LICENSE.md for details.
#

import struct
import subprocess
import sys
import tempfile

from elftools.elf.elffile import ELFFile


def main():
    arguments = sys.argv[1:]

    if (len(arguments) == 0) or ("--help" in arguments):
        print(f"Usage: {sys.argv[0]} COMPILER [ARGS ...]")
        return 0

    if "-c" not in arguments:
        arguments.append("-c")
    assert "-o" not in arguments

    with tempfile.NamedTemporaryFile(suffix=".o") as object_file:
        arguments += ["-o", object_file.name]
        subprocess.check_call(arguments)

        elf = ELFFile(object_file)
        symtab = elf.get_section_by_name(".symtab")
        assert symtab is not None

        targets = [
            (
                symbol.name,
                symbol.entry.st_size,
                (elf.get_section(symbol.entry.st_shndx).header.sh_offset + symbol.entry.st_value),
            )
            for symbol in symtab.iter_symbols()
            if (
                symbol.name
                and symbol.entry.st_info.bind == "STB_GLOBAL"
                and symbol.entry.st_info.type == "STT_OBJECT"
            )
        ]

        stream = elf.stream
        direction = "<" if elf.little_endian else ">"
        size_map = {1: "B", 2: "H", 4: "I", 8: "Q"}
        for name, size, offset in targets:
            stream.seek(offset)
            buffer = stream.read(size)
            assert len(buffer) == size
            value = struct.unpack(direction + size_map[size], buffer)[0]
            print(f"{name},{hex(value)}")

    return 0


if __name__ == "__main__":
    sys.exit(main())