releasetools: Move verity related functions into verity_utils.py.
This prepares for upcoming changes that refactor verity-related functions into classes. This CL makes minimal changes to the moved functions, by creating a new BuildVerityImageError class in verity_utils.py replacing the former BuildImageError that's specific to build_image.py. As part of the change, it also moves the tests for AVBCalcMinPartitionSize into test_verity_utils.py. Test: python -m unittest test_verity_utils Test: `m dist` with aosp_marlin-userdebug (Verified Boot 1.0) Test: `m dist` with aosp_taimen-userdebug (Verified Boot 2.0) Change-Id: I19b52714d8980705ea1f9484ac03eb0af9483240
This commit is contained in:
Tao Bao
@@ -16,13 +16,354 @@
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from __future__ import print_function
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import os.path
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import shlex
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import struct
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import common
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from build_image import (AdjustPartitionSizeForVerity, GetVerityTreeSize,
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GetVerityMetadataSize, BuildVerityTree)
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import sparse_img
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from rangelib import RangeSet
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OPTIONS = common.OPTIONS
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BLOCK_SIZE = common.BLOCK_SIZE
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FIXED_SALT = "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"
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class BuildVerityImageError(Exception):
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"""An Exception raised during verity image building."""
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def __init__(self, message):
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Exception.__init__(self, message)
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def GetVerityFECSize(partition_size):
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cmd = ["fec", "-s", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVerityTreeSize(partition_size):
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cmd = ["build_verity_tree", "-s", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVerityMetadataSize(partition_size):
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cmd = ["build_verity_metadata.py", "size", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVeritySize(partition_size, fec_supported):
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verity_tree_size = GetVerityTreeSize(partition_size)
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verity_metadata_size = GetVerityMetadataSize(partition_size)
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verity_size = verity_tree_size + verity_metadata_size
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if fec_supported:
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fec_size = GetVerityFECSize(partition_size + verity_size)
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return verity_size + fec_size
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return verity_size
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def GetSimgSize(image_file):
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simg = sparse_img.SparseImage(image_file, build_map=False)
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return simg.blocksize * simg.total_blocks
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def ZeroPadSimg(image_file, pad_size):
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blocks = pad_size // BLOCK_SIZE
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print("Padding %d blocks (%d bytes)" % (blocks, pad_size))
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simg = sparse_img.SparseImage(image_file, mode="r+b", build_map=False)
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simg.AppendFillChunk(0, blocks)
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def AdjustPartitionSizeForVerity(partition_size, fec_supported):
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"""Modifies the provided partition size to account for the verity metadata.
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This information is used to size the created image appropriately.
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Args:
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partition_size: the size of the partition to be verified.
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Returns:
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A tuple of the size of the partition adjusted for verity metadata, and
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the size of verity metadata.
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"""
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key = "%d %d" % (partition_size, fec_supported)
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if key in AdjustPartitionSizeForVerity.results:
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return AdjustPartitionSizeForVerity.results[key]
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hi = partition_size
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if hi % BLOCK_SIZE != 0:
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hi = (hi // BLOCK_SIZE) * BLOCK_SIZE
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# verity tree and fec sizes depend on the partition size, which
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# means this estimate is always going to be unnecessarily small
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verity_size = GetVeritySize(hi, fec_supported)
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lo = partition_size - verity_size
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result = lo
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# do a binary search for the optimal size
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while lo < hi:
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i = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
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v = GetVeritySize(i, fec_supported)
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if i + v <= partition_size:
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if result < i:
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result = i
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verity_size = v
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lo = i + BLOCK_SIZE
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else:
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hi = i
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if OPTIONS.verbose:
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print("Adjusted partition size for verity, partition_size: {},"
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" verity_size: {}".format(result, verity_size))
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AdjustPartitionSizeForVerity.results[key] = (result, verity_size)
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return (result, verity_size)
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AdjustPartitionSizeForVerity.results = {}
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def BuildVerityFEC(sparse_image_path, verity_path, verity_fec_path,
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padding_size):
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cmd = ["fec", "-e", "-p", str(padding_size), sparse_image_path,
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verity_path, verity_fec_path]
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common.RunAndCheckOutput(cmd)
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def BuildVerityTree(sparse_image_path, verity_image_path):
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cmd = ["build_verity_tree", "-A", FIXED_SALT, sparse_image_path,
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verity_image_path]
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output = common.RunAndCheckOutput(cmd)
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root, salt = output.split()
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return root, salt
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def BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
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block_device, signer_path, key, signer_args,
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verity_disable):
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cmd = ["build_verity_metadata.py", "build", str(image_size),
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verity_metadata_path, root_hash, salt, block_device, signer_path, key]
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if signer_args:
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cmd.append("--signer_args=\"%s\"" % (' '.join(signer_args),))
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if verity_disable:
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cmd.append("--verity_disable")
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common.RunAndCheckOutput(cmd)
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def Append2Simg(sparse_image_path, unsparse_image_path, error_message):
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"""Appends the unsparse image to the given sparse image.
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Args:
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sparse_image_path: the path to the (sparse) image
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unsparse_image_path: the path to the (unsparse) image
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Raises:
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BuildVerityImageError: On error.
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"""
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cmd = ["append2simg", sparse_image_path, unsparse_image_path]
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try:
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common.RunAndCheckOutput(cmd)
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except:
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raise BuildVerityImageError(error_message)
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def Append(target, file_to_append, error_message):
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"""Appends file_to_append to target.
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Raises:
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BuildVerityImageError: On error.
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"""
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try:
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with open(target, "a") as out_file, open(file_to_append, "r") as input_file:
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for line in input_file:
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out_file.write(line)
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except IOError:
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raise BuildVerityImageError(error_message)
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def BuildVerifiedImage(data_image_path, verity_image_path,
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verity_metadata_path, verity_fec_path,
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padding_size, fec_supported):
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Append(
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verity_image_path, verity_metadata_path,
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"Could not append verity metadata!")
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if fec_supported:
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# Build FEC for the entire partition, including metadata.
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BuildVerityFEC(
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data_image_path, verity_image_path, verity_fec_path, padding_size)
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Append(verity_image_path, verity_fec_path, "Could not append FEC!")
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Append2Simg(
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data_image_path, verity_image_path, "Could not append verity data!")
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def MakeVerityEnabledImage(out_file, fec_supported, prop_dict):
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"""Creates an image that is verifiable using dm-verity.
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Args:
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out_file: the location to write the verifiable image at
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prop_dict: a dictionary of properties required for image creation and
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verification
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Raises:
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AssertionError: On invalid partition sizes.
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"""
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# get properties
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image_size = int(prop_dict["image_size"])
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block_dev = prop_dict["verity_block_device"]
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signer_key = prop_dict["verity_key"] + ".pk8"
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if OPTIONS.verity_signer_path is not None:
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signer_path = OPTIONS.verity_signer_path
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else:
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signer_path = prop_dict["verity_signer_cmd"]
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signer_args = OPTIONS.verity_signer_args
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tempdir_name = common.MakeTempDir(suffix="_verity_images")
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# Get partial image paths.
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verity_image_path = os.path.join(tempdir_name, "verity.img")
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verity_metadata_path = os.path.join(tempdir_name, "verity_metadata.img")
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verity_fec_path = os.path.join(tempdir_name, "verity_fec.img")
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# Build the verity tree and get the root hash and salt.
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root_hash, salt = BuildVerityTree(out_file, verity_image_path)
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# Build the metadata blocks.
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verity_disable = "verity_disable" in prop_dict
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BuildVerityMetadata(
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image_size, verity_metadata_path, root_hash, salt, block_dev, signer_path,
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signer_key, signer_args, verity_disable)
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# Build the full verified image.
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partition_size = int(prop_dict["partition_size"])
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verity_size = int(prop_dict["verity_size"])
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padding_size = partition_size - image_size - verity_size
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assert padding_size >= 0
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BuildVerifiedImage(
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out_file, verity_image_path, verity_metadata_path, verity_fec_path,
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padding_size, fec_supported)
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def AVBCalcMaxImageSize(avbtool, footer_type, partition_size, additional_args):
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"""Calculates max image size for a given partition size.
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Args:
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avbtool: String with path to avbtool.
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footer_type: 'hash' or 'hashtree' for generating footer.
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partition_size: The size of the partition in question.
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additional_args: Additional arguments to pass to "avbtool add_hash_footer"
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or "avbtool add_hashtree_footer".
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Returns:
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The maximum image size.
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Raises:
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BuildVerityImageError: On invalid image size.
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"""
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cmd = [avbtool, "add_%s_footer" % footer_type,
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"--partition_size", str(partition_size), "--calc_max_image_size"]
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cmd.extend(shlex.split(additional_args))
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output = common.RunAndCheckOutput(cmd)
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image_size = int(output)
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if image_size <= 0:
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raise BuildVerityImageError(
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"Invalid max image size: {}".format(output))
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return image_size
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def AVBCalcMinPartitionSize(image_size, size_calculator):
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"""Calculates min partition size for a given image size.
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Args:
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image_size: The size of the image in question.
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size_calculator: The function to calculate max image size
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for a given partition size.
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Returns:
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The minimum partition size required to accommodate the image size.
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"""
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# Use image size as partition size to approximate final partition size.
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image_ratio = size_calculator(image_size) / float(image_size)
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# Prepare a binary search for the optimal partition size.
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lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - BLOCK_SIZE
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# Ensure lo is small enough: max_image_size should <= image_size.
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delta = BLOCK_SIZE
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max_image_size = size_calculator(lo)
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while max_image_size > image_size:
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image_ratio = max_image_size / float(lo)
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lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - delta
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delta *= 2
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max_image_size = size_calculator(lo)
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hi = lo + BLOCK_SIZE
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# Ensure hi is large enough: max_image_size should >= image_size.
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delta = BLOCK_SIZE
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max_image_size = size_calculator(hi)
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while max_image_size < image_size:
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image_ratio = max_image_size / float(hi)
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hi = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE + delta
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delta *= 2
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max_image_size = size_calculator(hi)
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partition_size = hi
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# Start to binary search.
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while lo < hi:
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mid = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
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max_image_size = size_calculator(mid)
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if max_image_size >= image_size: # if mid can accommodate image_size
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if mid < partition_size: # if a smaller partition size is found
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partition_size = mid
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hi = mid
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else:
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lo = mid + BLOCK_SIZE
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if OPTIONS.verbose:
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print("AVBCalcMinPartitionSize({}): partition_size: {}.".format(
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image_size, partition_size))
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return partition_size
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def AVBAddFooter(image_path, avbtool, footer_type, partition_size,
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partition_name, key_path, algorithm, salt,
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additional_args):
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"""Adds dm-verity hashtree and AVB metadata to an image.
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Args:
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image_path: Path to image to modify.
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avbtool: String with path to avbtool.
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footer_type: 'hash' or 'hashtree' for generating footer.
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partition_size: The size of the partition in question.
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partition_name: The name of the partition - will be embedded in metadata.
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key_path: Path to key to use or None.
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algorithm: Name of algorithm to use or None.
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salt: The salt to use (a hexadecimal string) or None.
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additional_args: Additional arguments to pass to "avbtool add_hash_footer"
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or "avbtool add_hashtree_footer".
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"""
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cmd = [avbtool, "add_%s_footer" % footer_type,
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"--partition_size", partition_size,
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"--partition_name", partition_name,
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"--image", image_path]
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if key_path and algorithm:
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cmd.extend(["--key", key_path, "--algorithm", algorithm])
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if salt:
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cmd.extend(["--salt", salt])
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cmd.extend(shlex.split(additional_args))
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common.RunAndCheckOutput(cmd)
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class HashtreeInfoGenerationError(Exception):
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"""An Exception raised during hashtree info generation."""
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