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341 lines
11 KiB
341 lines
11 KiB
# Copyright (c) 2013 The Chromium OS Authors. All rights reserved. |
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# Use of this source code is governed by a BSD-style license that can be |
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# found in the LICENSE file. |
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"""Tools for reading, verifying and applying Chrome OS update payloads.""" |
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from __future__ import print_function |
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import hashlib |
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import struct |
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import applier |
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import block_tracer |
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import checker |
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import common |
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from error import PayloadError |
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import update_metadata_pb2 |
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# |
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# Helper functions. |
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# |
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def _ReadInt(file_obj, size, is_unsigned, hasher=None): |
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"""Reads a binary-encoded integer from a file. |
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It will do the correct conversion based on the reported size and whether or |
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not a signed number is expected. Assumes a network (big-endian) byte |
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ordering. |
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Args: |
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file_obj: a file object |
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size: the integer size in bytes (2, 4 or 8) |
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is_unsigned: whether it is signed or not |
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hasher: an optional hasher to pass the value through |
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Returns: |
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An "unpacked" (Python) integer value. |
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Raises: |
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PayloadError if an read error occurred. |
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""" |
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return struct.unpack(common.IntPackingFmtStr(size, is_unsigned), |
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common.Read(file_obj, size, hasher=hasher))[0] |
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# |
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# Update payload. |
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# |
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class Payload(object): |
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"""Chrome OS update payload processor.""" |
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class _PayloadHeader(object): |
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"""Update payload header struct.""" |
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# Header constants; sizes are in bytes. |
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_MAGIC = 'CrAU' |
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_VERSION_SIZE = 8 |
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_MANIFEST_LEN_SIZE = 8 |
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_METADATA_SIGNATURE_LEN_SIZE = 4 |
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def __init__(self): |
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self.version = None |
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self.manifest_len = None |
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self.metadata_signature_len = None |
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self.size = None |
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def ReadFromPayload(self, payload_file, hasher=None): |
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"""Reads the payload header from a file. |
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Reads the payload header from the |payload_file| and updates the |hasher| |
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if one is passed. The parsed header is stored in the _PayloadHeader |
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instance attributes. |
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Args: |
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payload_file: a file object |
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hasher: an optional hasher to pass the value through |
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Returns: |
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None. |
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Raises: |
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PayloadError if a read error occurred or the header is invalid. |
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""" |
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# Verify magic |
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magic = common.Read(payload_file, len(self._MAGIC), hasher=hasher) |
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if magic != self._MAGIC: |
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raise PayloadError('invalid payload magic: %s' % magic) |
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self.version = _ReadInt(payload_file, self._VERSION_SIZE, True, |
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hasher=hasher) |
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self.manifest_len = _ReadInt(payload_file, self._MANIFEST_LEN_SIZE, True, |
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hasher=hasher) |
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self.size = (len(self._MAGIC) + self._VERSION_SIZE + |
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self._MANIFEST_LEN_SIZE) |
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self.metadata_signature_len = 0 |
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if self.version == common.BRILLO_MAJOR_PAYLOAD_VERSION: |
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self.size += self._METADATA_SIGNATURE_LEN_SIZE |
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self.metadata_signature_len = _ReadInt( |
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payload_file, self._METADATA_SIGNATURE_LEN_SIZE, True, |
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hasher=hasher) |
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def __init__(self, payload_file): |
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"""Initialize the payload object. |
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Args: |
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payload_file: update payload file object open for reading |
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""" |
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self.payload_file = payload_file |
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self.manifest_hasher = None |
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self.is_init = False |
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self.header = None |
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self.manifest = None |
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self.data_offset = None |
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self.metadata_signature = None |
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self.metadata_size = None |
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def _ReadHeader(self): |
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"""Reads and returns the payload header. |
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Returns: |
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A payload header object. |
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Raises: |
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PayloadError if a read error occurred. |
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""" |
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header = self._PayloadHeader() |
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header.ReadFromPayload(self.payload_file, self.manifest_hasher) |
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return header |
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def _ReadManifest(self): |
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"""Reads and returns the payload manifest. |
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Returns: |
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A string containing the payload manifest in binary form. |
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Raises: |
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PayloadError if a read error occurred. |
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""" |
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if not self.header: |
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raise PayloadError('payload header not present') |
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return common.Read(self.payload_file, self.header.manifest_len, |
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hasher=self.manifest_hasher) |
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def _ReadMetadataSignature(self): |
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"""Reads and returns the metadata signatures. |
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Returns: |
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A string containing the metadata signatures protobuf in binary form or |
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an empty string if no metadata signature found in the payload. |
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Raises: |
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PayloadError if a read error occurred. |
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""" |
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if not self.header: |
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raise PayloadError('payload header not present') |
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return common.Read( |
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self.payload_file, self.header.metadata_signature_len, |
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offset=self.header.size + self.header.manifest_len) |
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def ReadDataBlob(self, offset, length): |
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"""Reads and returns a single data blob from the update payload. |
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Args: |
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offset: offset to the beginning of the blob from the end of the manifest |
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length: the blob's length |
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Returns: |
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A string containing the raw blob data. |
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Raises: |
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PayloadError if a read error occurred. |
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""" |
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return common.Read(self.payload_file, length, |
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offset=self.data_offset + offset) |
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def Init(self): |
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"""Initializes the payload object. |
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This is a prerequisite for any other public API call. |
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Raises: |
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PayloadError if object already initialized or fails to initialize |
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correctly. |
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""" |
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if self.is_init: |
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raise PayloadError('payload object already initialized') |
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# Initialize hash context. |
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# pylint: disable=E1101 |
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self.manifest_hasher = hashlib.sha256() |
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# Read the file header. |
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self.header = self._ReadHeader() |
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# Read the manifest. |
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manifest_raw = self._ReadManifest() |
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self.manifest = update_metadata_pb2.DeltaArchiveManifest() |
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self.manifest.ParseFromString(manifest_raw) |
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# Read the metadata signature (if any). |
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metadata_signature_raw = self._ReadMetadataSignature() |
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if metadata_signature_raw: |
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self.metadata_signature = update_metadata_pb2.Signatures() |
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self.metadata_signature.ParseFromString(metadata_signature_raw) |
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self.metadata_size = self.header.size + self.header.manifest_len |
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self.data_offset = self.metadata_size + self.header.metadata_signature_len |
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self.is_init = True |
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def Describe(self): |
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"""Emits the payload embedded description data to standard output.""" |
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def _DescribeImageInfo(description, image_info): |
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def _DisplayIndentedValue(name, value): |
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print(' {:<14} {}'.format(name+':', value)) |
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print('%s:' % description) |
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_DisplayIndentedValue('Channel', image_info.channel) |
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_DisplayIndentedValue('Board', image_info.board) |
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_DisplayIndentedValue('Version', image_info.version) |
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_DisplayIndentedValue('Key', image_info.key) |
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if image_info.build_channel != image_info.channel: |
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_DisplayIndentedValue('Build channel', image_info.build_channel) |
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if image_info.build_version != image_info.version: |
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_DisplayIndentedValue('Build version', image_info.build_version) |
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if self.manifest.HasField('old_image_info'): |
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# pylint: disable=E1101 |
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_DescribeImageInfo('Old Image', self.manifest.old_image_info) |
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if self.manifest.HasField('new_image_info'): |
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# pylint: disable=E1101 |
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_DescribeImageInfo('New Image', self.manifest.new_image_info) |
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def _AssertInit(self): |
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"""Raises an exception if the object was not initialized.""" |
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if not self.is_init: |
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raise PayloadError('payload object not initialized') |
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def ResetFile(self): |
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"""Resets the offset of the payload file to right past the manifest.""" |
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self.payload_file.seek(self.data_offset) |
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def IsDelta(self): |
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"""Returns True iff the payload appears to be a delta.""" |
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self._AssertInit() |
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return (self.manifest.HasField('old_kernel_info') or |
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self.manifest.HasField('old_rootfs_info') or |
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any(partition.HasField('old_partition_info') |
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for partition in self.manifest.partitions)) |
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def IsFull(self): |
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"""Returns True iff the payload appears to be a full.""" |
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return not self.IsDelta() |
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def Check(self, pubkey_file_name=None, metadata_sig_file=None, |
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report_out_file=None, assert_type=None, block_size=0, |
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rootfs_part_size=0, kernel_part_size=0, allow_unhashed=False, |
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disabled_tests=()): |
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"""Checks the payload integrity. |
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Args: |
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pubkey_file_name: public key used for signature verification |
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metadata_sig_file: metadata signature, if verification is desired |
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report_out_file: file object to dump the report to |
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assert_type: assert that payload is either 'full' or 'delta' |
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block_size: expected filesystem / payload block size |
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rootfs_part_size: the size of (physical) rootfs partitions in bytes |
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kernel_part_size: the size of (physical) kernel partitions in bytes |
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allow_unhashed: allow unhashed operation blobs |
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disabled_tests: list of tests to disable |
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Raises: |
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PayloadError if payload verification failed. |
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""" |
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self._AssertInit() |
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# Create a short-lived payload checker object and run it. |
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helper = checker.PayloadChecker( |
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self, assert_type=assert_type, block_size=block_size, |
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allow_unhashed=allow_unhashed, disabled_tests=disabled_tests) |
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helper.Run(pubkey_file_name=pubkey_file_name, |
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metadata_sig_file=metadata_sig_file, |
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rootfs_part_size=rootfs_part_size, |
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kernel_part_size=kernel_part_size, |
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report_out_file=report_out_file) |
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def Apply(self, new_kernel_part, new_rootfs_part, old_kernel_part=None, |
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old_rootfs_part=None, bsdiff_in_place=True, bspatch_path=None, |
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truncate_to_expected_size=True): |
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"""Applies the update payload. |
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Args: |
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new_kernel_part: name of dest kernel partition file |
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new_rootfs_part: name of dest rootfs partition file |
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old_kernel_part: name of source kernel partition file (optional) |
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old_rootfs_part: name of source rootfs partition file (optional) |
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bsdiff_in_place: whether to perform BSDIFF operations in-place (optional) |
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bspatch_path: path to the bspatch binary (optional) |
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truncate_to_expected_size: whether to truncate the resulting partitions |
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to their expected sizes, as specified in the |
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payload (optional) |
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Raises: |
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PayloadError if payload application failed. |
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""" |
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self._AssertInit() |
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# Create a short-lived payload applier object and run it. |
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helper = applier.PayloadApplier( |
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self, bsdiff_in_place=bsdiff_in_place, bspatch_path=bspatch_path, |
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truncate_to_expected_size=truncate_to_expected_size) |
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helper.Run(new_kernel_part, new_rootfs_part, |
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old_kernel_part=old_kernel_part, |
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old_rootfs_part=old_rootfs_part) |
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def TraceBlock(self, block, skip, trace_out_file, is_kernel): |
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"""Traces the origin(s) of a given dest partition block. |
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The tracing tries to find origins transitively, when possible (it currently |
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only works for move operations, where the mapping of src/dst is |
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one-to-one). It will dump a list of operations and source blocks |
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responsible for the data in the given dest block. |
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Args: |
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block: the block number whose origin to trace |
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skip: the number of first origin mappings to skip |
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trace_out_file: file object to dump the trace to |
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is_kernel: trace through kernel (True) or rootfs (False) operations |
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""" |
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self._AssertInit() |
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# Create a short-lived payload block tracer object and run it. |
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helper = block_tracer.PayloadBlockTracer(self) |
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helper.Run(block, skip, trace_out_file, is_kernel)
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