# # Copyright (C) 2013 The Android Open Source Project # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # """Applying a Chrome OS update payload. This module is used internally by the main Payload class for applying an update payload. The interface for invoking the applier is as follows: applier = PayloadApplier(payload) applier.Run(...) """ from __future__ import absolute_import from __future__ import print_function import array import bz2 import hashlib # Not everywhere we can have the lzma library so we ignore it if we didn't have # it because it is not going to be used. For example, 'cros flash' uses # devserver code which eventually loads this file, but the lzma library is not # included in the client test devices, and it is not necessary to do so. But # lzma is not used in 'cros flash' so it should be fine. Python 3.x include # lzma, but for backward compatibility with Python 2.7, backports-lzma is # needed. try: import lzma except ImportError: try: from backports import lzma except ImportError: pass import os import subprocess import sys import tempfile from update_payload import common from update_payload.error import PayloadError # # Helper functions. # def _VerifySha256(file_obj, expected_hash, name, length=-1): """Verifies the SHA256 hash of a file. Args: file_obj: file object to read expected_hash: the hash digest we expect to be getting name: name string of this hash, for error reporting length: precise length of data to verify (optional) Raises: PayloadError if computed hash doesn't match expected one, or if fails to read the specified length of data. """ hasher = hashlib.sha256() block_length = 1024 * 1024 max_length = length if length >= 0 else sys.maxsize while max_length > 0: read_length = min(max_length, block_length) data = file_obj.read(read_length) if not data: break max_length -= len(data) hasher.update(data) if length >= 0 and max_length > 0: raise PayloadError( 'insufficient data (%d instead of %d) when verifying %s' % (length - max_length, length, name)) actual_hash = hasher.digest() if actual_hash != expected_hash: raise PayloadError('%s hash (%s) not as expected (%s)' % (name, common.FormatSha256(actual_hash), common.FormatSha256(expected_hash))) def _ReadExtents(file_obj, extents, block_size, max_length=-1): """Reads data from file as defined by extent sequence. This tries to be efficient by not copying data as it is read in chunks. Args: file_obj: file object extents: sequence of block extents (offset and length) block_size: size of each block max_length: maximum length to read (optional) Returns: A character array containing the concatenated read data. """ data = array.array('B') if max_length < 0: max_length = sys.maxsize for ex in extents: if max_length == 0: break read_length = min(max_length, ex.num_blocks * block_size) file_obj.seek(ex.start_block * block_size) data.fromfile(file_obj, read_length) max_length -= read_length return data def _WriteExtents(file_obj, data, extents, block_size, base_name): """Writes data to file as defined by extent sequence. This tries to be efficient by not copy data as it is written in chunks. Args: file_obj: file object data: data to write extents: sequence of block extents (offset and length) block_size: size of each block base_name: name string of extent sequence for error reporting Raises: PayloadError when things don't add up. """ data_offset = 0 data_length = len(data) for ex, ex_name in common.ExtentIter(extents, base_name): if not data_length: raise PayloadError('%s: more write extents than data' % ex_name) write_length = min(data_length, ex.num_blocks * block_size) file_obj.seek(ex.start_block * block_size) file_obj.write(data[data_offset:(data_offset + write_length)]) data_offset += write_length data_length -= write_length if data_length: raise PayloadError('%s: more data than write extents' % base_name) def _ExtentsToBspatchArg(extents, block_size, base_name, data_length=-1): """Translates an extent sequence into a bspatch-compatible string argument. Args: extents: sequence of block extents (offset and length) block_size: size of each block base_name: name string of extent sequence for error reporting data_length: the actual total length of the data in bytes (optional) Returns: A tuple consisting of (i) a string of the form "off_1:len_1,...,off_n:len_n", (ii) an offset where zero padding is needed for filling the last extent, (iii) the length of the padding (zero means no padding is needed and the extents cover the full length of data). Raises: PayloadError if data_length is too short or too long. """ arg = '' pad_off = pad_len = 0 if data_length < 0: data_length = sys.maxsize for ex, ex_name in common.ExtentIter(extents, base_name): if not data_length: raise PayloadError('%s: more extents than total data length' % ex_name) start_byte = ex.start_block * block_size num_bytes = ex.num_blocks * block_size if data_length < num_bytes: # We're only padding a real extent. pad_off = start_byte + data_length pad_len = num_bytes - data_length num_bytes = data_length arg += '%s%d:%d' % (arg and ',', start_byte, num_bytes) data_length -= num_bytes if data_length: raise PayloadError('%s: extents not covering full data length' % base_name) return arg, pad_off, pad_len # # Payload application. # class PayloadApplier(object): """Applying an update payload. This is a short-lived object whose purpose is to isolate the logic used for applying an update payload. """ def __init__(self, payload, bsdiff_in_place=True, bspatch_path=None, puffpatch_path=None, truncate_to_expected_size=True): """Initialize the applier. Args: payload: the payload object to check bsdiff_in_place: whether to perform BSDIFF operation in-place (optional) bspatch_path: path to the bspatch binary (optional) puffpatch_path: path to the puffpatch binary (optional) truncate_to_expected_size: whether to truncate the resulting partitions to their expected sizes, as specified in the payload (optional) """ assert payload.is_init, 'uninitialized update payload' self.payload = payload self.block_size = payload.manifest.block_size self.minor_version = payload.manifest.minor_version self.bsdiff_in_place = bsdiff_in_place self.bspatch_path = bspatch_path or 'bspatch' self.puffpatch_path = puffpatch_path or 'puffin' self.truncate_to_expected_size = truncate_to_expected_size def _ApplyReplaceOperation(self, op, op_name, out_data, part_file, part_size): """Applies a REPLACE{,_BZ,_XZ} operation. Args: op: the operation object op_name: name string for error reporting out_data: the data to be written part_file: the partition file object part_size: the size of the partition Raises: PayloadError if something goes wrong. """ block_size = self.block_size data_length = len(out_data) # Decompress data if needed. if op.type == common.OpType.REPLACE_BZ: out_data = bz2.decompress(out_data) data_length = len(out_data) elif op.type == common.OpType.REPLACE_XZ: # pylint: disable=no-member out_data = lzma.decompress(out_data) data_length = len(out_data) # Write data to blocks specified in dst extents. data_start = 0 for ex, ex_name in common.ExtentIter(op.dst_extents, '%s.dst_extents' % op_name): start_block = ex.start_block num_blocks = ex.num_blocks count = num_blocks * block_size data_end = data_start + count # Make sure we're not running past partition boundary. if (start_block + num_blocks) * block_size > part_size: raise PayloadError( '%s: extent (%s) exceeds partition size (%d)' % (ex_name, common.FormatExtent(ex, block_size), part_size)) # Make sure that we have enough data to write. if data_end >= data_length + block_size: raise PayloadError( '%s: more dst blocks than data (even with padding)') # Pad with zeros if necessary. if data_end > data_length: padding = data_end - data_length out_data += b'\0' * padding self.payload.payload_file.seek(start_block * block_size) part_file.seek(start_block * block_size) part_file.write(out_data[data_start:data_end]) data_start += count # Make sure we wrote all data. if data_start < data_length: raise PayloadError('%s: wrote fewer bytes (%d) than expected (%d)' % (op_name, data_start, data_length)) def _ApplyZeroOperation(self, op, op_name, part_file): """Applies a ZERO operation. Args: op: the operation object op_name: name string for error reporting part_file: the partition file object Raises: PayloadError if something goes wrong. """ block_size = self.block_size base_name = '%s.dst_extents' % op_name # Iterate over the extents and write zero. # pylint: disable=unused-variable for ex, ex_name in common.ExtentIter(op.dst_extents, base_name): part_file.seek(ex.start_block * block_size) part_file.write(b'\0' * (ex.num_blocks * block_size)) def _ApplySourceCopyOperation(self, op, op_name, old_part_file, new_part_file): """Applies a SOURCE_COPY operation. Args: op: the operation object op_name: name string for error reporting old_part_file: the old partition file object new_part_file: the new partition file object Raises: PayloadError if something goes wrong. """ if not old_part_file: raise PayloadError( '%s: no source partition file provided for operation type (%d)' % (op_name, op.type)) block_size = self.block_size # Gather input raw data from src extents. in_data = _ReadExtents(old_part_file, op.src_extents, block_size) # Dump extracted data to dst extents. _WriteExtents(new_part_file, in_data, op.dst_extents, block_size, '%s.dst_extents' % op_name) def _BytesInExtents(self, extents, base_name): """Counts the length of extents in bytes. Args: extents: The list of Extents. base_name: For error reporting. Returns: The number of bytes in extents. """ length = 0 # pylint: disable=unused-variable for ex, ex_name in common.ExtentIter(extents, base_name): length += ex.num_blocks * self.block_size return length def _ApplyDiffOperation(self, op, op_name, patch_data, old_part_file, new_part_file): """Applies a SOURCE_BSDIFF, BROTLI_BSDIFF or PUFFDIFF operation. Args: op: the operation object op_name: name string for error reporting patch_data: the binary patch content old_part_file: the source partition file object new_part_file: the target partition file object Raises: PayloadError if something goes wrong. """ if not old_part_file: raise PayloadError( '%s: no source partition file provided for operation type (%d)' % (op_name, op.type)) block_size = self.block_size # Dump patch data to file. with tempfile.NamedTemporaryFile(delete=False) as patch_file: patch_file_name = patch_file.name patch_file.write(patch_data) if (hasattr(new_part_file, 'fileno') and ((not old_part_file) or hasattr(old_part_file, 'fileno'))): # Construct input and output extents argument for bspatch. in_extents_arg, _, _ = _ExtentsToBspatchArg( op.src_extents, block_size, '%s.src_extents' % op_name, data_length=op.src_length if op.src_length else self._BytesInExtents(op.src_extents, "%s.src_extents")) out_extents_arg, pad_off, pad_len = _ExtentsToBspatchArg( op.dst_extents, block_size, '%s.dst_extents' % op_name, data_length=op.dst_length if op.dst_length else self._BytesInExtents(op.dst_extents, "%s.dst_extents")) new_file_name = '/dev/fd/%d' % new_part_file.fileno() # Diff from source partition. old_file_name = '/dev/fd/%d' % old_part_file.fileno() # In python3, file descriptors(fd) are not passed to child processes by # default. To pass the fds to the child processes, we need to set the flag # 'inheritable' in the fds and make the subprocess calls with the argument # close_fds set to False. if sys.version_info.major >= 3: os.set_inheritable(new_part_file.fileno(), True) os.set_inheritable(old_part_file.fileno(), True) if op.type in (common.OpType.SOURCE_BSDIFF, common.OpType.BROTLI_BSDIFF): # Invoke bspatch on partition file with extents args. bspatch_cmd = [self.bspatch_path, old_file_name, new_file_name, patch_file_name, in_extents_arg, out_extents_arg] subprocess.check_call(bspatch_cmd, close_fds=False) elif op.type == common.OpType.PUFFDIFF: # Invoke puffpatch on partition file with extents args. puffpatch_cmd = [self.puffpatch_path, "--operation=puffpatch", "--src_file=%s" % old_file_name, "--dst_file=%s" % new_file_name, "--patch_file=%s" % patch_file_name, "--src_extents=%s" % in_extents_arg, "--dst_extents=%s" % out_extents_arg] subprocess.check_call(puffpatch_cmd, close_fds=False) else: raise PayloadError("Unknown operation %s" % op.type) # Pad with zeros past the total output length. if pad_len: new_part_file.seek(pad_off) new_part_file.write(b'\0' * pad_len) else: # Gather input raw data and write to a temp file. input_part_file = old_part_file if old_part_file else new_part_file in_data = _ReadExtents(input_part_file, op.src_extents, block_size, max_length=op.src_length if op.src_length else self._BytesInExtents(op.src_extents, "%s.src_extents")) with tempfile.NamedTemporaryFile(delete=False) as in_file: in_file_name = in_file.name in_file.write(in_data) # Allocate temporary output file. with tempfile.NamedTemporaryFile(delete=False) as out_file: out_file_name = out_file.name if op.type in (common.OpType.SOURCE_BSDIFF, common.OpType.BROTLI_BSDIFF): # Invoke bspatch. bspatch_cmd = [self.bspatch_path, in_file_name, out_file_name, patch_file_name] subprocess.check_call(bspatch_cmd) elif op.type == common.OpType.PUFFDIFF: # Invoke puffpatch. puffpatch_cmd = [self.puffpatch_path, "--operation=puffpatch", "--src_file=%s" % in_file_name, "--dst_file=%s" % out_file_name, "--patch_file=%s" % patch_file_name] subprocess.check_call(puffpatch_cmd) else: raise PayloadError("Unknown operation %s" % op.type) # Read output. with open(out_file_name, 'rb') as out_file: out_data = out_file.read() if len(out_data) != op.dst_length: raise PayloadError( '%s: actual patched data length (%d) not as expected (%d)' % (op_name, len(out_data), op.dst_length)) # Write output back to partition, with padding. unaligned_out_len = len(out_data) % block_size if unaligned_out_len: out_data += b'\0' * (block_size - unaligned_out_len) _WriteExtents(new_part_file, out_data, op.dst_extents, block_size, '%s.dst_extents' % op_name) # Delete input/output files. os.remove(in_file_name) os.remove(out_file_name) # Delete patch file. os.remove(patch_file_name) def _ApplyOperations(self, operations, base_name, old_part_file, new_part_file, part_size): """Applies a sequence of update operations to a partition. Args: operations: the sequence of operations base_name: the name of the operation sequence old_part_file: the old partition file object, open for reading/writing new_part_file: the new partition file object, open for reading/writing part_size: the partition size Raises: PayloadError if anything goes wrong while processing the payload. """ for op, op_name in common.OperationIter(operations, base_name): # Read data blob. data = self.payload.ReadDataBlob(op.data_offset, op.data_length) if op.type in (common.OpType.REPLACE, common.OpType.REPLACE_BZ, common.OpType.REPLACE_XZ): self._ApplyReplaceOperation(op, op_name, data, new_part_file, part_size) elif op.type == common.OpType.ZERO: self._ApplyZeroOperation(op, op_name, new_part_file) elif op.type == common.OpType.SOURCE_COPY: self._ApplySourceCopyOperation(op, op_name, old_part_file, new_part_file) elif op.type in (common.OpType.SOURCE_BSDIFF, common.OpType.PUFFDIFF, common.OpType.BROTLI_BSDIFF): self._ApplyDiffOperation(op, op_name, data, old_part_file, new_part_file) else: raise PayloadError('%s: unknown operation type (%d)' % (op_name, op.type)) def _ApplyToPartition(self, operations, part_name, base_name, new_part_file_name, new_part_info, old_part_file_name=None, old_part_info=None): """Applies an update to a partition. Args: operations: the sequence of update operations to apply part_name: the name of the partition, for error reporting base_name: the name of the operation sequence new_part_file_name: file name to write partition data to new_part_info: size and expected hash of dest partition old_part_file_name: file name of source partition (optional) old_part_info: size and expected hash of source partition (optional) Raises: PayloadError if anything goes wrong with the update. """ # Do we have a source partition? if old_part_file_name: # Verify the source partition. with open(old_part_file_name, 'rb') as old_part_file: _VerifySha256(old_part_file, old_part_info.hash, 'old ' + part_name, length=old_part_info.size) new_part_file_mode = 'r+b' open(new_part_file_name, 'w').close() else: # We need to create/truncate the dst partition file. new_part_file_mode = 'w+b' # Apply operations. with open(new_part_file_name, new_part_file_mode) as new_part_file: old_part_file = (open(old_part_file_name, 'r+b') if old_part_file_name else None) try: self._ApplyOperations(operations, base_name, old_part_file, new_part_file, new_part_info.size) finally: if old_part_file: old_part_file.close() # Truncate the result, if so instructed. if self.truncate_to_expected_size: new_part_file.seek(0, 2) if new_part_file.tell() > new_part_info.size: new_part_file.seek(new_part_info.size) new_part_file.truncate() # Verify the resulting partition. with open(new_part_file_name, 'rb') as new_part_file: _VerifySha256(new_part_file, new_part_info.hash, 'new ' + part_name, length=new_part_info.size) def Run(self, new_parts, old_parts=None): """Applier entry point, invoking all update operations. Args: new_parts: map of partition name to dest partition file old_parts: map of partition name to source partition file (optional) Raises: PayloadError if payload application failed. """ if old_parts is None: old_parts = {} self.payload.ResetFile() new_part_info = {} old_part_info = {} install_operations = [] manifest = self.payload.manifest for part in manifest.partitions: name = part.partition_name new_part_info[name] = part.new_partition_info old_part_info[name] = part.old_partition_info install_operations.append((name, part.operations)) part_names = set(new_part_info.keys()) # Equivalently, old_part_info.keys() # Make sure the arguments are sane and match the payload. new_part_names = set(new_parts.keys()) if new_part_names != part_names: raise PayloadError('missing dst partition(s) %s' % ', '.join(part_names - new_part_names)) old_part_names = set(old_parts.keys()) if part_names - old_part_names: if self.payload.IsDelta(): raise PayloadError('trying to apply a delta update without src ' 'partition(s) %s' % ', '.join(part_names - old_part_names)) elif old_part_names == part_names: if self.payload.IsFull(): raise PayloadError('trying to apply a full update onto src partitions') else: raise PayloadError('not all src partitions provided') for name, operations in install_operations: # Apply update to partition. self._ApplyToPartition( operations, name, '%s_install_operations' % name, new_parts[name], new_part_info[name], old_parts.get(name, None), old_part_info[name])