1 # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 """Utilities for update payload processing.""" 6 7 from __future__ import print_function 8 9 from update_payload import update_metadata_pb2 10 from update_payload.error import PayloadError 11 12 13 # 14 # Constants. 15 # 16 PSEUDO_EXTENT_MARKER = (1L << 64) - 1 # UINT64_MAX 17 18 SIG_ASN1_HEADER = ( 19 '\x30\x31\x30\x0d\x06\x09\x60\x86' 20 '\x48\x01\x65\x03\x04\x02\x01\x05' 21 '\x00\x04\x20' 22 ) 23 24 CHROMEOS_MAJOR_PAYLOAD_VERSION = 1 25 BRILLO_MAJOR_PAYLOAD_VERSION = 2 26 27 INPLACE_MINOR_PAYLOAD_VERSION = 1 28 SOURCE_MINOR_PAYLOAD_VERSION = 2 29 OPSRCHASH_MINOR_PAYLOAD_VERSION = 3 30 BROTLI_BSDIFF_MINOR_PAYLOAD_VERSION = 4 31 PUFFDIFF_MINOR_PAYLOAD_VERSION = 5 32 33 # 34 # Payload operation types. 35 # 36 class OpType(object): 37 """Container for operation type constants.""" 38 _CLASS = update_metadata_pb2.InstallOperation 39 REPLACE = _CLASS.REPLACE 40 REPLACE_BZ = _CLASS.REPLACE_BZ 41 MOVE = _CLASS.MOVE 42 BSDIFF = _CLASS.BSDIFF 43 SOURCE_COPY = _CLASS.SOURCE_COPY 44 SOURCE_BSDIFF = _CLASS.SOURCE_BSDIFF 45 ZERO = _CLASS.ZERO 46 DISCARD = _CLASS.DISCARD 47 REPLACE_XZ = _CLASS.REPLACE_XZ 48 PUFFDIFF = _CLASS.PUFFDIFF 49 BROTLI_BSDIFF = _CLASS.BROTLI_BSDIFF 50 ALL = (REPLACE, REPLACE_BZ, MOVE, BSDIFF, SOURCE_COPY, SOURCE_BSDIFF, ZERO, 51 DISCARD, REPLACE_XZ, PUFFDIFF, BROTLI_BSDIFF) 52 NAMES = { 53 REPLACE: 'REPLACE', 54 REPLACE_BZ: 'REPLACE_BZ', 55 MOVE: 'MOVE', 56 BSDIFF: 'BSDIFF', 57 SOURCE_COPY: 'SOURCE_COPY', 58 SOURCE_BSDIFF: 'SOURCE_BSDIFF', 59 ZERO: 'ZERO', 60 DISCARD: 'DISCARD', 61 REPLACE_XZ: 'REPLACE_XZ', 62 PUFFDIFF: 'PUFFDIFF', 63 BROTLI_BSDIFF: 'BROTLI_BSDIFF', 64 } 65 66 def __init__(self): 67 pass 68 69 70 # 71 # Checked and hashed reading of data. 72 # 73 def IntPackingFmtStr(size, is_unsigned): 74 """Returns an integer format string for use by the struct module. 75 76 Args: 77 size: the integer size in bytes (2, 4 or 8) 78 is_unsigned: whether it is signed or not 79 80 Returns: 81 A format string for packing/unpacking integer values; assumes network byte 82 order (big-endian). 83 84 Raises: 85 PayloadError if something is wrong with the arguments. 86 """ 87 # Determine the base conversion format. 88 if size == 2: 89 fmt = 'h' 90 elif size == 4: 91 fmt = 'i' 92 elif size == 8: 93 fmt = 'q' 94 else: 95 raise PayloadError('unsupport numeric field size (%s)' % size) 96 97 # Signed or unsigned? 98 if is_unsigned: 99 fmt = fmt.upper() 100 101 # Make it network byte order (big-endian). 102 fmt = '!' + fmt 103 104 return fmt 105 106 107 def Read(file_obj, length, offset=None, hasher=None): 108 """Reads binary data from a file. 109 110 Args: 111 file_obj: an open file object 112 length: the length of the data to read 113 offset: an offset to seek to prior to reading; this is an absolute offset 114 from either the beginning (non-negative) or end (negative) of the 115 file. (optional) 116 hasher: a hashing object to pass the read data through (optional) 117 118 Returns: 119 A string containing the read data. 120 121 Raises: 122 PayloadError if a read error occurred or not enough data was read. 123 """ 124 if offset is not None: 125 if offset >= 0: 126 file_obj.seek(offset) 127 else: 128 file_obj.seek(offset, 2) 129 130 try: 131 data = file_obj.read(length) 132 except IOError, e: 133 raise PayloadError('error reading from file (%s): %s' % (file_obj.name, e)) 134 135 if len(data) != length: 136 raise PayloadError( 137 'reading from file (%s) too short (%d instead of %d bytes)' % 138 (file_obj.name, len(data), length)) 139 140 if hasher: 141 hasher.update(data) 142 143 return data 144 145 146 # 147 # Formatting functions. 148 # 149 def FormatExtent(ex, block_size=0): 150 end_block = ex.start_block + ex.num_blocks 151 if block_size: 152 return '%d->%d * %d' % (ex.start_block, end_block, block_size) 153 else: 154 return '%d->%d' % (ex.start_block, end_block) 155 156 157 def FormatSha256(digest): 158 """Returns a canonical string representation of a SHA256 digest.""" 159 return digest.encode('base64').strip() 160 161 162 # 163 # Useful iterators. 164 # 165 def _ObjNameIter(items, base_name, reverse=False, name_format_func=None): 166 """A generic (item, name) tuple iterators. 167 168 Args: 169 items: the sequence of objects to iterate on 170 base_name: the base name for all objects 171 reverse: whether iteration should be in reverse order 172 name_format_func: a function to apply to the name string 173 174 Yields: 175 An iterator whose i-th invocation returns (items[i], name), where name == 176 base_name + '[i]' (with a formatting function optionally applied to it). 177 """ 178 idx, inc = (len(items), -1) if reverse else (1, 1) 179 if reverse: 180 items = reversed(items) 181 for item in items: 182 item_name = '%s[%d]' % (base_name, idx) 183 if name_format_func: 184 item_name = name_format_func(item, item_name) 185 yield (item, item_name) 186 idx += inc 187 188 189 def _OperationNameFormatter(op, op_name): 190 return '%s(%s)' % (op_name, OpType.NAMES.get(op.type, '?')) 191 192 193 def OperationIter(operations, base_name, reverse=False): 194 """An (item, name) iterator for update operations.""" 195 return _ObjNameIter(operations, base_name, reverse=reverse, 196 name_format_func=_OperationNameFormatter) 197 198 199 def ExtentIter(extents, base_name, reverse=False): 200 """An (item, name) iterator for operation extents.""" 201 return _ObjNameIter(extents, base_name, reverse=reverse) 202 203 204 def SignatureIter(sigs, base_name, reverse=False): 205 """An (item, name) iterator for signatures.""" 206 return _ObjNameIter(sigs, base_name, reverse=reverse) 207
