Created
July 10, 2024 11:30
-
-
Save mkagenius/ae07f9a3aacf5dafef831f76b8c12eb2 to your computer and use it in GitHub Desktop.
extract_android_ota_payload.py
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| #!/usr/bin/env python | |
| import hashlib | |
| import os | |
| import os.path | |
| import shutil | |
| import struct | |
| import subprocess | |
| import sys | |
| import zipfile | |
| # from https://android.googlesource.com/platform/system/update_engine/+/refs/heads/master/scripts/update_payload/ | |
| import update_metadata_pb2 | |
| PROGRAMS = [ 'bzcat', 'xzcat' ] | |
| BRILLO_MAJOR_PAYLOAD_VERSION = 2 | |
| class PayloadError(Exception): | |
| pass | |
| class Payload(object): | |
| class _PayloadHeader(object): | |
| _MAGIC = b'CrAU' | |
| def __init__(self): | |
| self.version = None | |
| self.manifest_len = None | |
| self.metadata_signature_len = None | |
| self.size = None | |
| def ReadFromPayload(self, payload_file): | |
| magic = payload_file.read(4) | |
| if magic != self._MAGIC: | |
| raise PayloadError('Invalid payload magic: %s' % magic) | |
| self.version = struct.unpack('>Q', payload_file.read(8))[0] | |
| self.manifest_len = struct.unpack('>Q', payload_file.read(8))[0] | |
| self.size = 20 | |
| self.metadata_signature_len = 0 | |
| if self.version != BRILLO_MAJOR_PAYLOAD_VERSION: | |
| raise PayloadError('Unsupported payload version (%d)' % self.version) | |
| self.size += 4 | |
| self.metadata_signature_len = struct.unpack('>I', payload_file.read(4))[0] | |
| def __init__(self, payload_file): | |
| self.payload_file = payload_file | |
| self.header = None | |
| self.manifest = None | |
| self.data_offset = None | |
| self.metadata_signature = None | |
| self.metadata_size = None | |
| def _ReadManifest(self): | |
| return self.payload_file.read(self.header.manifest_len) | |
| def _ReadMetadataSignature(self): | |
| self.payload_file.seek(self.header.size + self.header.manifest_len) | |
| return self.payload_file.read(self.header.metadata_signature_len); | |
| def ReadDataBlob(self, offset, length): | |
| self.payload_file.seek(self.data_offset + offset) | |
| return self.payload_file.read(length) | |
| def Init(self): | |
| self.header = self._PayloadHeader() | |
| self.header.ReadFromPayload(self.payload_file) | |
| manifest_raw = self._ReadManifest() | |
| self.manifest = update_metadata_pb2.DeltaArchiveManifest() | |
| self.manifest.ParseFromString(manifest_raw) | |
| metadata_signature_raw = self._ReadMetadataSignature() | |
| if metadata_signature_raw: | |
| self.metadata_signature = update_metadata_pb2.Signatures() | |
| self.metadata_signature.ParseFromString(metadata_signature_raw) | |
| self.metadata_size = self.header.size + self.header.manifest_len | |
| self.data_offset = self.metadata_size + self.header.metadata_signature_len | |
| def decompress_payload(command, data, size, hash): | |
| p = subprocess.Popen([command, '-'], stdout=subprocess.PIPE, stdin=subprocess.PIPE) | |
| r = p.communicate(data)[0] | |
| if len(r) != size: | |
| print("Unexpected size %d %d" % (len(r), size)) | |
| elif hashlib.sha256(data).digest() != hash: | |
| print("Hash mismatch") | |
| return r | |
| def parse_payload(payload_f, partition, out_f): | |
| BLOCK_SIZE = 4096 | |
| for operation in partition.operations: | |
| e = operation.dst_extents[0] | |
| data = payload_f.ReadDataBlob(operation.data_offset, operation.data_length) | |
| out_f.seek(e.start_block * BLOCK_SIZE) | |
| if operation.type == update_metadata_pb2.InstallOperation.REPLACE: | |
| out_f.write(data) | |
| elif operation.type == update_metadata_pb2.InstallOperation.REPLACE_XZ: | |
| r = decompress_payload('xzcat', data, e.num_blocks * BLOCK_SIZE, operation.data_sha256_hash) | |
| out_f.write(r) | |
| elif operation.type == update_metadata_pb2.InstallOperation.REPLACE_BZ: | |
| r = decompress_payload('bzcat', data, e.num_blocks * BLOCK_SIZE, operation.data_sha256_hash) | |
| out_f.write(r) | |
| elif operation.type == update_metadata_pb2.InstallOperation.ZERO: | |
| out_f.write(b'\x00' * (e.num_blocks * BLOCK_SIZE)) | |
| else: | |
| raise PayloadError('Unhandled operation type ({} - {})'.format(operation.type, | |
| update_metadata_pb2.InstallOperation.Type.Name(operation.type))) | |
| def main(filename, output_dir): | |
| if filename.endswith('.zip'): | |
| print("Extracting 'payload.bin' from OTA file...") | |
| ota_zf = zipfile.ZipFile(filename) | |
| payload_file = open(ota_zf.extract('payload.bin', output_dir), 'rb') | |
| else: | |
| payload_file = open(filename, 'rb') | |
| payload = Payload(payload_file) | |
| payload.Init() | |
| for p in payload.manifest.partitions: | |
| name = p.partition_name + '.img' | |
| print("Extracting '%s'" % name) | |
| fname = os.path.join(output_dir, name) | |
| out_f = open(fname, 'wb') | |
| try: | |
| parse_payload(payload, p, out_f) | |
| except PayloadError as e: | |
| print('Failed: %s' % e) | |
| out_f.close() | |
| os.unlink(fname) | |
| if __name__ == '__main__': | |
| try: | |
| filename = sys.argv[1] | |
| except: | |
| print('Usage: %s payload.bin [output_dir]' % sys.argv[0]) | |
| sys.exit() | |
| try: | |
| output_dir = sys.argv[2] | |
| except IndexError: | |
| output_dir = os.getcwd() | |
| if not os.path.exists(output_dir): | |
| os.makedirs(output_dir) | |
| main(filename, output_dir) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment