Prevent AVB signing from using _RESERVED_SIZE
When AVB is enabled with PRODUCT_USE_DYNAMIC_PARTITION_SIZE, AVB
metadata (e.g., hash tree, fec metadata) will consume _RESERVED_SIZE,
resulting in smaller reserved size in file system (e.g., ext4).
Adding additional space for AVB signing and keep the _RESERVED_SIZE only
for file system. This is done by adding a function to binary search an
optimal partition size for a given image size (disk usage + _RESERVED_SIZE).
Bug: 112322265
Test: Build aosp_arm64-userdebug, calculate the running time of
AVBCalcMinPartitionSize() is about 0.3-0.4 seconds.
Test: python -m unittest test_build_image
Change-Id: I8f0051b57701d6fbba6a9db3756dd194066c74b8
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index c422280..e198f40 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -149,13 +149,14 @@
avbtool: String with path to avbtool.
footer_type: 'hash' or 'hashtree' for generating footer.
partition_size: The size of the partition in question.
- additional_args: Additional arguments to pass to 'avbtool
- add_hashtree_image'.
+ additional_args: Additional arguments to pass to "avbtool add_hash_footer"
+ or "avbtool add_hashtree_footer".
+
Returns:
The maximum image size or 0 if an error occurred.
"""
cmd = [avbtool, "add_%s_footer" % footer_type,
- "--partition_size", partition_size, "--calc_max_image_size"]
+ "--partition_size", str(partition_size), "--calc_max_image_size"]
cmd.extend(shlex.split(additional_args))
(output, exit_code) = RunCommand(cmd)
@@ -165,6 +166,63 @@
return int(output)
+def AVBCalcMinPartitionSize(image_size, size_calculator):
+ """Calculates min partition size for a given image size.
+
+ Args:
+ image_size: The size of the image in question.
+ size_calculator: The function to calculate max image size
+ for a given partition size.
+
+ Returns:
+ The minimum partition size required to accommodate the image size.
+ """
+ # Use image size as partition size to approximate final partition size.
+ image_ratio = size_calculator(image_size) / float(image_size)
+
+ # Prepare a binary search for the optimal partition size.
+ lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - BLOCK_SIZE
+
+ # Ensure lo is small enough: max_image_size should <= image_size.
+ delta = BLOCK_SIZE
+ max_image_size = size_calculator(lo)
+ while max_image_size > image_size:
+ image_ratio = max_image_size / float(lo)
+ lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - delta
+ delta *= 2
+ max_image_size = size_calculator(lo)
+
+ hi = lo + BLOCK_SIZE
+
+ # Ensure hi is large enough: max_image_size should >= image_size.
+ delta = BLOCK_SIZE
+ max_image_size = size_calculator(hi)
+ while max_image_size < image_size:
+ image_ratio = max_image_size / float(hi)
+ hi = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE + delta
+ delta *= 2
+ max_image_size = size_calculator(hi)
+
+ partition_size = hi
+
+ # Start to binary search.
+ while lo < hi:
+ mid = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
+ max_image_size = size_calculator(mid)
+ if max_image_size >= image_size: # if mid can accommodate image_size
+ if mid < partition_size: # if a smaller partition size is found
+ partition_size = mid
+ hi = mid
+ else:
+ lo = mid + BLOCK_SIZE
+
+ if OPTIONS.verbose:
+ print("AVBCalcMinPartitionSize({}): partition_size: {}.".format(
+ image_size, partition_size))
+
+ return partition_size
+
+
def AVBAddFooter(image_path, avbtool, footer_type, partition_size,
partition_name, key_path, algorithm, salt,
additional_args):
@@ -179,8 +237,8 @@
key_path: Path to key to use or None.
algorithm: Name of algorithm to use or None.
salt: The salt to use (a hexadecimal string) or None.
- additional_args: Additional arguments to pass to 'avbtool
- add_hashtree_image'.
+ additional_args: Additional arguments to pass to "avbtool add_hash_footer"
+ or "avbtool add_hashtree_footer".
Returns:
True if the operation succeeded.
@@ -549,6 +607,17 @@
verity_supported = prop_dict.get("verity") == "true"
verity_fec_supported = prop_dict.get("verity_fec") == "true"
+ avb_footer_type = None
+ if prop_dict.get("avb_hash_enable") == "true":
+ avb_footer_type = "hash"
+ elif prop_dict.get("avb_hashtree_enable") == "true":
+ avb_footer_type = "hashtree"
+
+ if avb_footer_type:
+ avbtool = prop_dict.get("avb_avbtool")
+ avb_signing_args = prop_dict.get(
+ "avb_add_" + avb_footer_type + "_footer_args")
+
if (prop_dict.get("use_dynamic_partition_size") == "true" and
"partition_size" not in prop_dict):
# if partition_size is not defined, use output of `du' + reserved_size
@@ -560,6 +629,13 @@
size += int(prop_dict.get("partition_reserved_size", 0))
# Round this up to a multiple of 4K so that avbtool works
size = common.RoundUpTo4K(size)
+ # Adjust partition_size to add more space for AVB footer, to prevent
+ # it from consuming partition_reserved_size.
+ if avb_footer_type:
+ size = AVBCalcMinPartitionSize(
+ size,
+ lambda x: AVBCalcMaxImageSize(
+ avbtool, avb_footer_type, x, avb_signing_args))
prop_dict["partition_size"] = str(size)
if OPTIONS.verbose:
print("Allocating %d MB for %s." % (size // BYTES_IN_MB, out_file))
@@ -576,20 +652,12 @@
prop_dict["image_size"] = str(image_size)
prop_dict["verity_size"] = str(verity_size)
- avb_footer_type = ''
- if prop_dict.get("avb_hash_enable") == "true":
- avb_footer_type = 'hash'
- elif prop_dict.get("avb_hashtree_enable") == "true":
- avb_footer_type = 'hashtree'
-
# Adjust the image size for AVB hash footer or AVB hashtree footer.
if avb_footer_type:
- avbtool = prop_dict["avb_avbtool"]
partition_size = prop_dict["partition_size"]
# avb_add_hash_footer_args or avb_add_hashtree_footer_args.
- additional_args = prop_dict["avb_add_" + avb_footer_type + "_footer_args"]
max_image_size = AVBCalcMaxImageSize(avbtool, avb_footer_type,
- partition_size, additional_args)
+ partition_size, avb_signing_args)
if max_image_size <= 0:
print("AVBCalcMaxImageSize is <= 0: %d" % max_image_size)
return False
@@ -722,18 +790,15 @@
# Add AVB HASH or HASHTREE footer (metadata).
if avb_footer_type:
- avbtool = prop_dict["avb_avbtool"]
partition_size = prop_dict["partition_size"]
partition_name = prop_dict["partition_name"]
# key_path and algorithm are only available when chain partition is used.
key_path = prop_dict.get("avb_key_path")
algorithm = prop_dict.get("avb_algorithm")
salt = prop_dict.get("avb_salt")
- # avb_add_hash_footer_args or avb_add_hashtree_footer_args
- additional_args = prop_dict["avb_add_" + avb_footer_type + "_footer_args"]
if not AVBAddFooter(out_file, avbtool, avb_footer_type,
partition_size, partition_name, key_path,
- algorithm, salt, additional_args):
+ algorithm, salt, avb_signing_args):
return False
if run_e2fsck and prop_dict.get("skip_fsck") != "true":
diff --git a/tools/releasetools/test_build_image.py b/tools/releasetools/test_build_image.py
index 40a7c85..0aaa847 100644
--- a/tools/releasetools/test_build_image.py
+++ b/tools/releasetools/test_build_image.py
@@ -15,11 +15,15 @@
#
import filecmp
+import math
import os.path
+import random
import unittest
import common
-from build_image import CheckHeadroom, RunCommand, SetUpInDirAndFsConfig
+from build_image import (
+ AVBCalcMinPartitionSize, BLOCK_SIZE,
+ CheckHeadroom, RunCommand, SetUpInDirAndFsConfig)
class BuildImageTest(unittest.TestCase):
@@ -28,6 +32,13 @@
EXT4FS_OUTPUT = (
"Created filesystem with 2777/129024 inodes and 515099/516099 blocks")
+ def setUp(self):
+ # To test AVBCalcMinPartitionSize(), by using 200MB to 2GB image size.
+ # - 51200 = 200MB * 1024 * 1024 / 4096
+ # - 524288 = 2GB * 1024 * 1024 * 1024 / 4096
+ self._image_sizes = [BLOCK_SIZE * random.randint(51200, 524288) + offset
+ for offset in range(BLOCK_SIZE)]
+
def tearDown(self):
common.Cleanup()
@@ -176,3 +187,51 @@
self.assertIn('fs-config-system\n', fs_config_data)
self.assertIn('fs-config-root\n', fs_config_data)
self.assertEqual('/', prop_dict['mount_point'])
+
+ def test_AVBCalcMinPartitionSize_LinearFooterSize(self):
+ """Tests with footer size which is linear to partition size."""
+ for image_size in self._image_sizes:
+ for ratio in 0.95, 0.56, 0.22:
+ expected_size = common.RoundUpTo4K(int(math.ceil(image_size / ratio)))
+ self.assertEqual(
+ expected_size,
+ AVBCalcMinPartitionSize(image_size, lambda x: int(x * ratio)))
+
+ def test_AVBCalcMinPartitionSize_SlowerGrowthFooterSize(self):
+ """Tests with footer size which grows slower than partition size."""
+
+ def _SizeCalculator(partition_size):
+ """Footer size is the power of 0.95 of partition size."""
+ # Minus footer size to return max image size.
+ return partition_size - int(math.pow(partition_size, 0.95))
+
+ for image_size in self._image_sizes:
+ min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
+ # Checks min_partition_size can accommodate image_size.
+ self.assertGreaterEqual(
+ _SizeCalculator(min_partition_size),
+ image_size)
+ # Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
+ self.assertLess(
+ _SizeCalculator(min_partition_size - BLOCK_SIZE),
+ image_size)
+
+ def test_AVBCalcMinPartitionSize_FasterGrowthFooterSize(self):
+ """Tests with footer size which grows faster than partition size."""
+
+ def _SizeCalculator(partition_size):
+ """Max image size is the power of 0.95 of partition size."""
+ # Max image size grows less than partition size, which means
+ # footer size grows faster than partition size.
+ return int(math.pow(partition_size, 0.95))
+
+ for image_size in self._image_sizes:
+ min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
+ # Checks min_partition_size can accommodate image_size.
+ self.assertGreaterEqual(
+ _SizeCalculator(min_partition_size),
+ image_size)
+ # Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
+ self.assertLess(
+ _SizeCalculator(min_partition_size - BLOCK_SIZE),
+ image_size)