#!/usr/bin/python3

# encoding: utf-8

# SPDX-FileCopyrightText: 2024 FC (Fay) Stegerman <[email protected]>

# SPDX-License-Identifier: AGPL-3.0-or-later

import hashlib

import os

import re

import struct

import zipfile

import zlib

from binascii import hexlify

from typing import Any, Dict, Match, Tuple

DEX_MAGIC = b"dex\n"

DEX_MAGIC_RE = re.compile(rb"dex\n(\d{3})\x00")

PROF_MAGIC = b"pro\x00"

PROF_010_P = b"010\x00"

CLASSES_DEX_RE = re.compile(r"classes\d*\.dex")

ASSET_PROF = "assets/dexopt/baseline.prof"

PG_MAP_ID_RE = re.compile(rb'(~~R8{"backend":"dex".*?"pg-map-id":")([0-9a-f]{7})(")')

ATTRS = ("compress_type", "create_system", "create_version", "date_time",

"external_attr", "extract_version", "flag_bits")

LEVELS = (9, 6, 4, 1)

class Error(RuntimeError):

pass

# FIXME: is there a better alternative?

class ReproducibleZipInfo(zipfile.ZipInfo):

"""Reproducible ZipInfo hack."""

if "_compresslevel" not in zipfile.ZipInfo.__slots__: # type: ignore[attr-defined]

if "compress_level" not in zipfile.ZipInfo.__slots__: # type: ignore[attr-defined]

raise Error("zipfile.ZipInfo has no ._compresslevel")

_compresslevel: int

_override: Dict[str, Any] = {}

def __init__(self, zinfo: zipfile.ZipInfo, **override: Any) -> None:

# pylint: disable=W0231

if override:

self._override = {**self._override, **override}

for k in self.__slots__:

if hasattr(zinfo, k):

setattr(self, k, getattr(zinfo, k))

def __getattribute__(self, name: str) -> Any:

if name != "_override":

try:

return self._override[name]

except KeyError:

pass

return object.__getattribute__(self, name)

def fix_pg_map_id(input_dir: str, output_dir: str, map_id: str) -> None:

file_data = {}

for filename in [ASSET_PROF] + sorted(os.listdir(input_dir)):

if re.fullmatch(CLASSES_DEX_RE, filename) or filename == ASSET_PROF:

print(f"reading {filename!r}...")

with open(os.path.join(input_dir, *filename.split("/")), "rb") as fh:

file_data[filename] = fh.read()

_fix_pg_map_id(file_data, map_id)

for filename, data in file_data.items():

print(f"writing {filename!r}...")

if "/" in filename:

os.makedirs(os.path.join(output_dir, *filename.split("/")[:-1]), exist_ok=True)

with open(os.path.join(output_dir, *filename.split("/")), "wb") as fh:

fh.write(data)

def fix_pg_map_id_apk(input_apk: str, output_apk: str, map_id: str) -> None:

with open(input_apk, "rb") as fh_raw:

with zipfile.ZipFile(input_apk) as zf_in:

with zipfile.ZipFile(output_apk, "w") as zf_out:

file_data = {}

for info in zf_in.infolist():

if re.fullmatch(CLASSES_DEX_RE, info.filename) or info.filename == ASSET_PROF:

print(f"reading {info.filename!r}...")

file_data[info.filename] = zf_in.read(info)

_fix_pg_map_id(file_data, map_id)

for info in zf_in.infolist():

attrs = {attr: getattr(info, attr) for attr in ATTRS}

zinfo = ReproducibleZipInfo(info, **attrs)

if info.compress_type == 8:

fh_raw.seek(info.header_offset)

n, m = struct.unpack("<HH", fh_raw.read(30)[26:30])

fh_raw.seek(info.header_offset + 30 + m + n)

ccrc = 0

size = info.compress_size

while size > 0:

ccrc = zlib.crc32(fh_raw.read(min(size, 4096)), ccrc)

size -= 4096

with zf_in.open(info) as fh_in:

comps = {lvl: zlib.compressobj(lvl, 8, -15) for lvl in LEVELS}

ccrcs = {lvl: 0 for lvl in LEVELS}

while True:

data = fh_in.read(4096)

if not data:

break

for lvl in LEVELS:

ccrcs[lvl] = zlib.crc32(comps[lvl].compress(data), ccrcs[lvl])

for lvl in LEVELS:

if ccrc == zlib.crc32(comps[lvl].flush(), ccrcs[lvl]):

zinfo._compresslevel = lvl

break

else:

raise Error(f"Unable to determine compresslevel for {info.filename!r}")

elif info.compress_type != 0:

raise Error(f"Unsupported compress_type {info.compress_type}")

if re.fullmatch(CLASSES_DEX_RE, info.filename) or info.filename == ASSET_PROF:

print(f"writing {info.filename!r}...")

zf_out.writestr(zinfo, file_data[info.filename])

else:

with zf_in.open(info) as fh_in:

with zf_out.open(zinfo, "w") as fh_out:

while True:

data = fh_in.read(4096)

if not data:

break

fh_out.write(data)

def _fix_pg_map_id(file_data: Dict[str, bytes], map_id: str) -> None:

crcs = {}

for filename in file_data:

if re.fullmatch(CLASSES_DEX_RE, filename):

print(f"fixing {filename!r}...")

data = _fix_dex_id_checksum(file_data[filename], map_id.encode())

file_data[filename] = data

crcs[filename] = zlib.crc32(data)

if ASSET_PROF in file_data:

print(f"fixing {ASSET_PROF!r}...")

file_data[ASSET_PROF] = _fix_prof_checksum(file_data[ASSET_PROF], crcs)

def _fix_dex_id_checksum(data: bytes, map_id: bytes) -> bytes:

def repl(m: Match[bytes]) -> bytes:

print(f"fixing pg-map-id: {m.group(2)!r} -> {map_id!r}")

return m.group(1) + map_id + m.group(3)

magic = data[:8]

if magic[:4] != DEX_MAGIC or not DEX_MAGIC_RE.fullmatch(magic):

raise Error(f"Unsupported magic {magic!r}")

print(f"dex version={int(magic[4:7]):03d}")

checksum, signature = struct.unpack("<I20s", data[8:32])

fixed_data = re.sub(PG_MAP_ID_RE, repl, data[32:])

if fixed_data == data[32:]:

print("(not modified)")

return data

fixed_sig = hashlib.sha1(fixed_data).digest()

print(f"fixing signature: {hexlify(signature).decode()} -> {hexlify(fixed_sig).decode()}")

fixed_data = fixed_sig + fixed_data

fixed_checksum = zlib.adler32(fixed_data)

print(f"fixing checksum: 0x{checksum:x} -> 0x{fixed_checksum:x}")

return magic + int.to_bytes(fixed_checksum, 4, "little") + fixed_data

def _fix_prof_checksum(data: bytes, crcs: Dict[str, int]) -> bytes:

magic, data = _split(data, 4)

version, data = _split(data, 4)

if magic == PROF_MAGIC:

if version == PROF_010_P:

print("prof version=010 P")

return PROF_MAGIC + PROF_010_P + _fix_prof_010_p_checksum(data, crcs)

else:

raise Error(f"Unsupported prof version {version!r}")

else:

raise Error(f"Unsupported magic {magic!r}")

def _fix_prof_010_p_checksum(data: bytes, crcs: Dict[str, int]) -> bytes:

num_dex_files, uncompressed_data_size, compressed_data_size, data = _unpack("<BII", data)

dex_data_headers = []

if len(data) != compressed_data_size:

raise Error("Compressed data size does not match")

data = zlib.decompress(data)

if len(data) != uncompressed_data_size:

raise Error("Uncompressed data size does not match")

for i in range(num_dex_files):

profile_key_size, num_type_ids, hot_method_region_size, \

dex_checksum, num_method_ids, data = _unpack("<HHIII", data)

profile_key, data = _split(data, profile_key_size)

filename = profile_key.decode()

fixed_checksum = crcs[filename]

if fixed_checksum != dex_checksum:

print(f"fixing {filename!r} checksum: 0x{dex_checksum:x} -> 0x{fixed_checksum:x}")

dex_data_headers.append(struct.pack(

"<HHIII", profile_key_size, num_type_ids, hot_method_region_size,

fixed_checksum, num_method_ids) + profile_key)

fixed_data = b"".join(dex_data_headers) + data

fixed_cdata = zlib.compress(fixed_data, 1)

fixed_hdr = struct.pack("<BII", num_dex_files, uncompressed_data_size, len(fixed_cdata))

return fixed_hdr + fixed_cdata

def _unpack(fmt: str, data: bytes) -> Any:

assert all(c in "<BHI" for c in fmt)

size = fmt.count("B") + 2 * fmt.count("H") + 4 * fmt.count("I")

return struct.unpack(fmt, data[:size]) + (data[size:],)

def _split(data: bytes, size: int) -> Tuple[bytes, bytes]:

return data[:size], data[size:]

if __name__ == "__main__":

import argparse

parser = argparse.ArgumentParser(prog="fix-pg-map-id.py")

parser.add_argument("input_dir_or_apk", metavar="INPUT_DIR_OR_APK")

parser.add_argument("output_dir_or_apk", metavar="OUTPUT_DIR_OR_APK")

parser.add_argument("pg_map_id", metavar="PG_MAP_ID")

args = parser.parse_args()

if os.path.isdir(args.input_dir_or_apk):

fix_pg_map_id(args.input_dir_or_apk, args.output_dir_or_apk, args.pg_map_id)

else:

fix_pg_map_id_apk(args.input_dir_or_apk, args.output_dir_or_apk, args.pg_map_id)

# vim: set tw=80 sw=4 sts=4 et fdm=marker :