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 error import PayloadError 10 import update_metadata_pb2 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 IMGDIFF_MINOR_PAYLOAD_VERSION = 4 31 32 # 33 # Payload operation types. 34 # 35 class OpType(object): 36 """Container for operation type constants.""" 37 _CLASS = update_metadata_pb2.InstallOperation 38 # pylint: disable=E1101 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 IMGDIFF = _CLASS.IMGDIFF 49 ALL = (REPLACE, REPLACE_BZ, MOVE, BSDIFF, SOURCE_COPY, SOURCE_BSDIFF, ZERO, 50 DISCARD, REPLACE_XZ, IMGDIFF) 51 NAMES = { 52 REPLACE: 'REPLACE', 53 REPLACE_BZ: 'REPLACE_BZ', 54 MOVE: 'MOVE', 55 BSDIFF: 'BSDIFF', 56 SOURCE_COPY: 'SOURCE_COPY', 57 SOURCE_BSDIFF: 'SOURCE_BSDIFF', 58 ZERO: 'ZERO', 59 DISCARD: 'DISCARD', 60 REPLACE_XZ: 'REPLACE_XZ', 61 IMGDIFF: 'IMGDIFF', 62 } 63 64 def __init__(self): 65 pass 66 67 68 # 69 # Checked and hashed reading of data. 70 # 71 def IntPackingFmtStr(size, is_unsigned): 72 """Returns an integer format string for use by the struct module. 73 74 Args: 75 size: the integer size in bytes (2, 4 or 8) 76 is_unsigned: whether it is signed or not 77 78 Returns: 79 A format string for packing/unpacking integer values; assumes network byte 80 order (big-endian). 81 82 Raises: 83 PayloadError if something is wrong with the arguments. 84 """ 85 # Determine the base conversion format. 86 if size == 2: 87 fmt = 'h' 88 elif size == 4: 89 fmt = 'i' 90 elif size == 8: 91 fmt = 'q' 92 else: 93 raise PayloadError('unsupport numeric field size (%s)' % size) 94 95 # Signed or unsigned? 96 if is_unsigned: 97 fmt = fmt.upper() 98 99 # Make it network byte order (big-endian). 100 fmt = '!' + fmt 101 102 return fmt 103 104 105 def Read(file_obj, length, offset=None, hasher=None): 106 """Reads binary data from a file. 107 108 Args: 109 file_obj: an open file object 110 length: the length of the data to read 111 offset: an offset to seek to prior to reading; this is an absolute offset 112 from either the beginning (non-negative) or end (negative) of the 113 file. (optional) 114 hasher: a hashing object to pass the read data through (optional) 115 116 Returns: 117 A string containing the read data. 118 119 Raises: 120 PayloadError if a read error occurred or not enough data was read. 121 """ 122 if offset is not None: 123 if offset >= 0: 124 file_obj.seek(offset) 125 else: 126 file_obj.seek(offset, 2) 127 128 try: 129 data = file_obj.read(length) 130 except IOError, e: 131 raise PayloadError('error reading from file (%s): %s' % (file_obj.name, e)) 132 133 if len(data) != length: 134 raise PayloadError( 135 'reading from file (%s) too short (%d instead of %d bytes)' % 136 (file_obj.name, len(data), length)) 137 138 if hasher: 139 hasher.update(data) 140 141 return data 142 143 144 # 145 # Formatting functions. 146 # 147 def FormatExtent(ex, block_size=0): 148 end_block = ex.start_block + ex.num_blocks 149 if block_size: 150 return '%d->%d * %d' % (ex.start_block, end_block, block_size) 151 else: 152 return '%d->%d' % (ex.start_block, end_block) 153 154 155 def FormatSha256(digest): 156 """Returns a canonical string representation of a SHA256 digest.""" 157 return digest.encode('base64').strip() 158 159 160 # 161 # Useful iterators. 162 # 163 def _ObjNameIter(items, base_name, reverse=False, name_format_func=None): 164 """A generic (item, name) tuple iterators. 165 166 Args: 167 items: the sequence of objects to iterate on 168 base_name: the base name for all objects 169 reverse: whether iteration should be in reverse order 170 name_format_func: a function to apply to the name string 171 172 Yields: 173 An iterator whose i-th invocation returns (items[i], name), where name == 174 base_name + '[i]' (with a formatting function optionally applied to it). 175 """ 176 idx, inc = (len(items), -1) if reverse else (1, 1) 177 if reverse: 178 items = reversed(items) 179 for item in items: 180 item_name = '%s[%d]' % (base_name, idx) 181 if name_format_func: 182 item_name = name_format_func(item, item_name) 183 yield (item, item_name) 184 idx += inc 185 186 187 def _OperationNameFormatter(op, op_name): 188 return '%s(%s)' % (op_name, OpType.NAMES.get(op.type, '?')) 189 190 191 def OperationIter(operations, base_name, reverse=False): 192 """An (item, name) iterator for update operations.""" 193 return _ObjNameIter(operations, base_name, reverse=reverse, 194 name_format_func=_OperationNameFormatter) 195 196 197 def ExtentIter(extents, base_name, reverse=False): 198 """An (item, name) iterator for operation extents.""" 199 return _ObjNameIter(extents, base_name, reverse=reverse) 200 201 202 def SignatureIter(sigs, base_name, reverse=False): 203 """An (item, name) iterator for signatures.""" 204 return _ObjNameIter(sigs, base_name, reverse=reverse) 205
