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# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Utilities for unit testing."""
import cStringIO
import hashlib
import struct
import subprocess
import common
import payload
import update_metadata_pb2
class TestError(Exception):
"""An error during testing of update payload code."""
# Private/public RSA keys used for testing.
_PRIVKEY_FILE_NAME = 'payload-test-key.pem'
def KiB(count):
return count << 10
def MiB(count):
return count << 20
def GiB(count):
return count << 30
def _WriteInt(file_obj, size, is_unsigned, val):
"""Writes a binary-encoded integer to a file.
It will do the correct conversion based on the reported size and whether or
not a signed number is expected. Assumes a network (big-endian) byte
file_obj: a file object
size: the integer size in bytes (2, 4 or 8)
is_unsigned: whether it is signed or not
val: integer value to encode
PayloadError if a write error occurred.
file_obj.write(struct.pack(common.IntPackingFmtStr(size, is_unsigned), val))
except IOError, e:
raise payload.PayloadError('error writing to file (%s): %s' %
(, e))
def _SetMsgField(msg, field_name, val):
"""Sets or clears a field in a protobuf message."""
if val is None:
setattr(msg, field_name, val)
def SignSha256(data, privkey_file_name):
"""Signs the data's SHA256 hash with an RSA private key.
data: the data whose SHA256 hash we want to sign
privkey_file_name: private key used for signing data
The signature string, prepended with an ASN1 header.
TestError if something goes wrong.
# pylint: disable=E1101
data_sha256_hash = common.SIG_ASN1_HEADER + hashlib.sha256(data).digest()
sign_cmd = ['openssl', 'rsautl', '-sign', '-inkey', privkey_file_name]
sign_process = subprocess.Popen(sign_cmd, stdin=subprocess.PIPE,
sig, _ = sign_process.communicate(input=data_sha256_hash)
except Exception as e:
raise TestError('signing subprocess failed: %s' % e)
return sig
class SignaturesGenerator(object):
"""Generates a payload signatures data block."""
def __init__(self):
self.sigs = update_metadata_pb2.Signatures()
def AddSig(self, version, data):
"""Adds a signature to the signature sequence.
version: signature version (None means do not assign)
data: signature binary data (None means do not assign)
# Pylint fails to identify a member of the Signatures message.
# pylint: disable=E1101
sig = self.sigs.signatures.add()
if version is not None:
sig.version = version
if data is not None: = data
def ToBinary(self):
"""Returns the binary representation of the signature block."""
return self.sigs.SerializeToString()
class PayloadGenerator(object):
"""Generates an update payload allowing low-level control.
manifest: the protobuf containing the payload manifest
version: the payload version identifier
block_size: the block size pertaining to update operations
def __init__(self, version=1):
self.manifest = update_metadata_pb2.DeltaArchiveManifest()
self.version = version
self.block_size = 0
def _WriteExtent(ex, val):
"""Returns an Extent message."""
start_block, num_blocks = val
_SetMsgField(ex, 'start_block', start_block)
_SetMsgField(ex, 'num_blocks', num_blocks)
def _AddValuesToRepeatedField(repeated_field, values, write_func):
"""Adds values to a repeated message field."""
if values:
for val in values:
new_item = repeated_field.add()
write_func(new_item, val)
def _AddExtents(extents_field, values):
"""Adds extents to an extents field."""
extents_field, values, PayloadGenerator._WriteExtent)
def SetBlockSize(self, block_size):
"""Sets the payload's block size."""
self.block_size = block_size
_SetMsgField(self.manifest, 'block_size', block_size)
def SetPartInfo(self, is_kernel, is_new, part_size, part_hash):
"""Set the partition info entry.
is_kernel: whether this is kernel partition info
is_new: whether to set old (False) or new (True) info
part_size: the partition size (in fact, filesystem size)
part_hash: the partition hash
if is_kernel:
# pylint: disable=E1101
part_info = (self.manifest.new_kernel_info if is_new
else self.manifest.old_kernel_info)
# pylint: disable=E1101
part_info = (self.manifest.new_rootfs_info if is_new
else self.manifest.old_rootfs_info)
_SetMsgField(part_info, 'size', part_size)
_SetMsgField(part_info, 'hash', part_hash)
def AddOperation(self, is_kernel, op_type, data_offset=None,
data_length=None, src_extents=None, src_length=None,
dst_extents=None, dst_length=None, data_sha256_hash=None):
"""Adds an InstallOperation entry."""
# pylint: disable=E1101
operations = (self.manifest.kernel_install_operations if is_kernel
else self.manifest.install_operations)
op = operations.add()
op.type = op_type
_SetMsgField(op, 'data_offset', data_offset)
_SetMsgField(op, 'data_length', data_length)
self._AddExtents(op.src_extents, src_extents)
_SetMsgField(op, 'src_length', src_length)
self._AddExtents(op.dst_extents, dst_extents)
_SetMsgField(op, 'dst_length', dst_length)
_SetMsgField(op, 'data_sha256_hash', data_sha256_hash)
def SetSignatures(self, sigs_offset, sigs_size):
"""Set the payload's signature block descriptors."""
_SetMsgField(self.manifest, 'signatures_offset', sigs_offset)
_SetMsgField(self.manifest, 'signatures_size', sigs_size)
def _WriteHeaderToFile(self, file_obj, manifest_len):
"""Writes a payload heaer to a file."""
# We need to access protected members in Payload for writing the header.
# pylint: disable=W0212
_WriteInt(file_obj, payload.Payload._VERSION_SIZE, True, self.version)
_WriteInt(file_obj, payload.Payload._MANIFEST_LEN_SIZE, True, manifest_len)
def WriteToFile(self, file_obj, manifest_len=-1, data_blobs=None,
sigs_data=None, padding=None):
"""Writes the payload content to a file.
file_obj: a file object open for writing
manifest_len: manifest len to dump (otherwise computed automatically)
data_blobs: a list of data blobs to be concatenated to the payload
sigs_data: a binary Signatures message to be concatenated to the payload
padding: stuff to dump past the normal data blobs provided (optional)
manifest = self.manifest.SerializeToString()
if manifest_len < 0:
manifest_len = len(manifest)
self._WriteHeaderToFile(file_obj, manifest_len)
if data_blobs:
for data_blob in data_blobs:
if sigs_data:
if padding:
class EnhancedPayloadGenerator(PayloadGenerator):
"""Payload generator with automatic handling of data blobs.
data_blobs: a list of blobs, in the order they were added
curr_offset: the currently consumed offset of blobs added to the payload
def __init__(self):
super(EnhancedPayloadGenerator, self).__init__()
self.data_blobs = []
self.curr_offset = 0
def AddData(self, data_blob):
"""Adds a (possibly orphan) data blob."""
data_length = len(data_blob)
data_offset = self.curr_offset
self.curr_offset += data_length
return data_length, data_offset
def AddOperationWithData(self, is_kernel, op_type, src_extents=None,
src_length=None, dst_extents=None, dst_length=None,
data_blob=None, do_hash_data_blob=True):
"""Adds an install operation and associated data blob.
This takes care of obtaining a hash of the data blob (if so instructed)
and appending it to the internally maintained list of blobs, including the
necessary offset/length accounting.
is_kernel: whether this is a kernel (True) or rootfs (False) operation
src_extents: list of (start, length) pairs indicating src block ranges
src_length: size of the src data in bytes (needed for BSDIFF)
dst_extents: list of (start, length) pairs indicating dst block ranges
dst_length: size of the dst data in bytes (needed for BSDIFF)
data_blob: a data blob associated with this operation
do_hash_data_blob: whether or not to compute and add a data blob hash
data_offset = data_length = data_sha256_hash = None
if data_blob is not None:
if do_hash_data_blob:
# pylint: disable=E1101
data_sha256_hash = hashlib.sha256(data_blob).digest()
data_length, data_offset = self.AddData(data_blob)
self.AddOperation(is_kernel, op_type, data_offset=data_offset,
data_length=data_length, src_extents=src_extents,
src_length=src_length, dst_extents=dst_extents,
dst_length=dst_length, data_sha256_hash=data_sha256_hash)
def WriteToFileWithData(self, file_obj, sigs_data=None,
is_pseudo_in_kernel=False, padding=None):
"""Writes the payload content to a file, optionally signing the content.
file_obj: a file object open for writing
sigs_data: signatures blob to be appended to the payload (optional;
payload signature fields assumed to be preset by the caller)
privkey_file_name: key used for signing the payload (optional; used only
if explicit signatures blob not provided)
do_add_pseudo_operation: whether a pseudo-operation should be added to
account for the signature blob
is_pseudo_in_kernel: whether the pseudo-operation should be added to
kernel (True) or rootfs (False) operations
padding: stuff to dump past the normal data blobs provided (optional)
TestError: if arguments are inconsistent or something goes wrong.
sigs_len = len(sigs_data) if sigs_data else 0
# Do we need to generate a genuine signatures blob?
do_generate_sigs_data = sigs_data is None and privkey_file_name
if do_generate_sigs_data:
# First, sign some arbitrary data to obtain the size of a signature blob.
fake_sig = SignSha256('fake-payload-data', privkey_file_name)
fake_sigs_gen = SignaturesGenerator()
fake_sigs_gen.AddSig(1, fake_sig)
sigs_len = len(fake_sigs_gen.ToBinary())
# Update the payload with proper signature attributes.
self.SetSignatures(self.curr_offset, sigs_len)
# Add a pseudo-operation to account for the signature blob, if requested.
if do_add_pseudo_operation:
if not self.block_size:
raise TestError('cannot add pseudo-operation without knowing the '
'payload block size')
is_pseudo_in_kernel, common.OpType.REPLACE,
data_offset=self.curr_offset, data_length=sigs_len,
(sigs_len + self.block_size - 1) / self.block_size)])
if do_generate_sigs_data:
# Once all payload fields are updated, dump and sign it.
temp_payload_file = cStringIO.StringIO()
self.WriteToFile(temp_payload_file, data_blobs=self.data_blobs)
sig = SignSha256(temp_payload_file.getvalue(), privkey_file_name)
sigs_gen = SignaturesGenerator()
sigs_gen.AddSig(1, sig)
sigs_data = sigs_gen.ToBinary()
assert len(sigs_data) == sigs_len, 'signature blob lengths mismatch'
# Dump the whole thing, complete with data and signature blob, to a file.
self.WriteToFile(file_obj, data_blobs=self.data_blobs, sigs_data=sigs_data,