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android13/system/update_engine/payload_generator/delta_diff_utils.cc

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//
// Copyright (C) 2015 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#include "update_engine/payload_generator/delta_diff_utils.h"
#include <endian.h>
#include <sys/user.h>
#if defined(__clang__)
// TODO(*): Remove these pragmas when b/35721782 is fixed.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmacro-redefined"
#endif
#include <ext2fs/ext2fs.h>
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
#include <unistd.h>
#include <algorithm>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <utility>
#include <vector>
#include <base/files/file_util.h>
#include <base/format_macros.h>
#include <base/strings/string_util.h>
#include <base/strings/stringprintf.h>
#include <base/threading/simple_thread.h>
#include <brillo/data_encoding.h>
#include <bsdiff/bsdiff.h>
#include <bsdiff/constants.h>
#include <bsdiff/control_entry.h>
#include <bsdiff/patch_reader.h>
#include <bsdiff/patch_writer_factory.h>
#include <puffin/brotli_util.h>
#include <puffin/utils.h>
#include <zucchini/buffer_view.h>
#include <zucchini/patch_writer.h>
#include <zucchini/zucchini.h>
#include "update_engine/common/hash_calculator.h"
#include "update_engine/common/subprocess.h"
#include "update_engine/common/utils.h"
#include "update_engine/payload_consumer/payload_constants.h"
#include "update_engine/payload_generator/ab_generator.h"
#include "update_engine/payload_generator/block_mapping.h"
#include "update_engine/payload_generator/bzip.h"
#include "update_engine/payload_generator/deflate_utils.h"
#include "update_engine/payload_generator/delta_diff_generator.h"
#include "update_engine/payload_generator/extent_ranges.h"
#include "update_engine/payload_generator/extent_utils.h"
#include "update_engine/payload_generator/merge_sequence_generator.h"
#include "update_engine/payload_generator/squashfs_filesystem.h"
#include "update_engine/payload_generator/xz.h"
#include "update_engine/lz4diff/lz4diff.h"
using std::list;
using std::map;
using std::string;
using std::vector;
namespace chromeos_update_engine {
namespace {
// The maximum destination size allowed for bsdiff. In general, bsdiff should
// work for arbitrary big files, but the payload generation and payload
// application requires a significant amount of RAM. We put a hard-limit of
// 200 MiB that should not affect any released board, but will limit the
// Chrome binary in ASan builders.
const uint64_t kMaxBsdiffDestinationSize = 200 * 1024 * 1024; // bytes
// The maximum destination size allowed for puffdiff. In general, puffdiff
// should work for arbitrary big files, but the payload application is quite
// memory intensive, so we limit these operations to 150 MiB.
const uint64_t kMaxPuffdiffDestinationSize = 150 * 1024 * 1024; // bytes
// The maximum destination size allowed for zucchini. We are conservative here
// as zucchini tends to use more peak memory.
const uint64_t kMaxZucchiniDestinationSize = 150 * 1024 * 1024; // bytes
const int kBrotliCompressionQuality = 11;
// Storing a diff operation has more overhead over replace operation in the
// manifest, we need to store an additional src_sha256_hash which is 32 bytes
// and not compressible, and also src_extents which could use anywhere from a
// few bytes to hundreds of bytes depending on the number of extents.
// This function evaluates the overhead tradeoff and determines if it's worth to
// use a diff operation with data blob of |diff_size| and |num_src_extents|
// extents over an existing |op| with data blob of |old_blob_size|.
bool IsDiffOperationBetter(const InstallOperation& op,
size_t old_blob_size,
size_t diff_size,
size_t num_src_extents) {
if (!diff_utils::IsAReplaceOperation(op.type()))
return diff_size < old_blob_size;
// Reference: https://developers.google.com/protocol-buffers/docs/encoding
// For |src_sha256_hash| we need 1 byte field number/type, 1 byte size and 32
// bytes data, for |src_extents| we need 1 byte field number/type and 1 byte
// size.
constexpr size_t kDiffOverhead = 1 + 1 + 32 + 1 + 1;
// Each extent has two variable length encoded uint64, here we use a rough
// estimate of 6 bytes overhead per extent, since |num_blocks| is usually
// very small.
constexpr size_t kDiffOverheadPerExtent = 6;
return diff_size + kDiffOverhead + num_src_extents * kDiffOverheadPerExtent <
old_blob_size;
}
// Returns the levenshtein distance between string |a| and |b|.
// https://en.wikipedia.org/wiki/Levenshtein_distance
int LevenshteinDistance(const string& a, const string& b) {
vector<int> distances(a.size() + 1);
std::iota(distances.begin(), distances.end(), 0);
for (size_t i = 1; i <= b.size(); i++) {
distances[0] = i;
int previous_distance = i - 1;
for (size_t j = 1; j <= a.size(); j++) {
int new_distance =
std::min({distances[j] + 1,
distances[j - 1] + 1,
previous_distance + (a[j - 1] == b[i - 1] ? 0 : 1)});
previous_distance = distances[j];
distances[j] = new_distance;
}
}
return distances.back();
}
static bool ShouldCreateNewOp(const std::vector<CowMergeOperation>& ops,
size_t src_block,
size_t dst_block,
size_t src_offset) {
if (ops.empty()) {
return true;
}
const auto& op = ops.back();
if (op.src_offset() != src_offset) {
return true;
}
const auto& src_extent = op.src_extent();
const auto& dst_extent = op.dst_extent();
return src_extent.start_block() + src_extent.num_blocks() != src_block ||
dst_extent.start_block() + dst_extent.num_blocks() != dst_block;
}
void AppendXorBlock(std::vector<CowMergeOperation>* ops,
size_t src_block,
size_t dst_block,
size_t src_offset) {
if (!ops->empty() && ExtentContains(ops->back().dst_extent(), dst_block)) {
return;
}
CHECK_NE(src_block, std::numeric_limits<uint64_t>::max());
CHECK_NE(dst_block, std::numeric_limits<uint64_t>::max());
if (ShouldCreateNewOp(*ops, src_block, dst_block, src_offset)) {
auto& op = ops->emplace_back();
op.mutable_src_extent()->set_start_block(src_block);
op.mutable_src_extent()->set_num_blocks(1);
op.mutable_dst_extent()->set_start_block(dst_block);
op.mutable_dst_extent()->set_num_blocks(1);
op.set_src_offset(src_offset);
op.set_type(CowMergeOperation::COW_XOR);
} else {
auto& op = ops->back();
auto& src_extent = *op.mutable_src_extent();
auto& dst_extent = *op.mutable_dst_extent();
src_extent.set_num_blocks(src_extent.num_blocks() + 1);
dst_extent.set_num_blocks(dst_extent.num_blocks() + 1);
}
}
} // namespace
namespace diff_utils {
bool BestDiffGenerator::GenerateBestDiffOperation(AnnotatedOperation* aop,
brillo::Blob* data_blob) {
std::vector<std::pair<InstallOperation_Type, size_t>> diff_candidates = {
{InstallOperation::SOURCE_BSDIFF, kMaxBsdiffDestinationSize},
{InstallOperation::PUFFDIFF, kMaxPuffdiffDestinationSize},
{InstallOperation::ZUCCHINI, kMaxZucchiniDestinationSize},
};
return GenerateBestDiffOperation(diff_candidates, aop, data_blob);
}
std::vector<bsdiff::CompressorType>
BestDiffGenerator::GetUsableCompressorTypes() const {
return config_.compressors;
}
bool BestDiffGenerator::GenerateBestDiffOperation(
const std::vector<std::pair<InstallOperation_Type, size_t>>&
diff_candidates,
AnnotatedOperation* aop,
brillo::Blob* data_blob) {
CHECK(aop);
CHECK(data_blob);
if (!old_block_info_.blocks.empty() && !new_block_info_.blocks.empty() &&
config_.OperationEnabled(InstallOperation::LZ4DIFF_BSDIFF) &&
config_.OperationEnabled(InstallOperation::LZ4DIFF_PUFFDIFF)) {
brillo::Blob patch;
InstallOperation::Type op_type;
if (Lz4Diff(old_data_,
new_data_,
old_block_info_,
new_block_info_,
&patch,
&op_type)) {
aop->op.set_type(op_type);
// LZ4DIFF is likely significantly better than BSDIFF/PUFFDIFF when
// working with EROFS. So no need to even try other diffing algorithms.
*data_blob = std::move(patch);
return true;
}
}
const uint64_t input_bytes = std::max(utils::BlocksInExtents(src_extents_),
utils::BlocksInExtents(dst_extents_)) *
kBlockSize;
for (auto [op_type, limit] : diff_candidates) {
if (!config_.OperationEnabled(op_type)) {
continue;
}
// Disable the specific diff algorithm when the data is too big.
if (input_bytes > limit) {
LOG(INFO) << op_type << " ignored, file " << aop->name
<< " too big: " << input_bytes << " bytes";
continue;
}
// Prefer BROTLI_BSDIFF as it gives smaller patch size.
if (op_type == InstallOperation::SOURCE_BSDIFF &&
config_.OperationEnabled(InstallOperation::BROTLI_BSDIFF)) {
op_type = InstallOperation::BROTLI_BSDIFF;
}
switch (op_type) {
case InstallOperation::SOURCE_BSDIFF:
case InstallOperation::BROTLI_BSDIFF:
TEST_AND_RETURN_FALSE(
TryBsdiffAndUpdateOperation(op_type, aop, data_blob));
break;
case InstallOperation::PUFFDIFF:
TEST_AND_RETURN_FALSE(TryPuffdiffAndUpdateOperation(aop, data_blob));
break;
case InstallOperation::ZUCCHINI:
TEST_AND_RETURN_FALSE(TryZucchiniAndUpdateOperation(aop, data_blob));
break;
default:
NOTREACHED();
}
}
return true;
}
bool BestDiffGenerator::TryBsdiffAndUpdateOperation(
InstallOperation_Type operation_type,
AnnotatedOperation* aop,
brillo::Blob* data_blob) {
base::FilePath patch;
TEST_AND_RETURN_FALSE(base::CreateTemporaryFile(&patch));
ScopedPathUnlinker unlinker(patch.value());
std::unique_ptr<bsdiff::PatchWriterInterface> bsdiff_patch_writer;
if (operation_type == InstallOperation::BROTLI_BSDIFF) {
bsdiff_patch_writer = bsdiff::CreateBSDF2PatchWriter(
patch.value(), GetUsableCompressorTypes(), kBrotliCompressionQuality);
} else {
bsdiff_patch_writer = bsdiff::CreateBsdiffPatchWriter(patch.value());
}
brillo::Blob bsdiff_delta;
TEST_AND_RETURN_FALSE(0 == bsdiff::bsdiff(old_data_.data(),
old_data_.size(),
new_data_.data(),
new_data_.size(),
bsdiff_patch_writer.get(),
nullptr));
TEST_AND_RETURN_FALSE(utils::ReadFile(patch.value(), &bsdiff_delta));
TEST_AND_RETURN_FALSE(!bsdiff_delta.empty());
InstallOperation& operation = aop->op;
if (IsDiffOperationBetter(operation,
data_blob->size(),
bsdiff_delta.size(),
src_extents_.size())) {
// VABC XOR won't work with compressed files just yet.
if (config_.enable_vabc_xor) {
StoreExtents(src_extents_, operation.mutable_src_extents());
diff_utils::PopulateXorOps(aop, bsdiff_delta);
}
operation.set_type(operation_type);
*data_blob = std::move(bsdiff_delta);
}
return true;
}
bool BestDiffGenerator::TryPuffdiffAndUpdateOperation(AnnotatedOperation* aop,
brillo::Blob* data_blob) {
// Only Puffdiff if both files have at least one deflate left.
if (!old_deflates_.empty() && !new_deflates_.empty()) {
brillo::Blob puffdiff_delta;
ScopedTempFile temp_file("puffdiff-delta.XXXXXX");
// Perform PuffDiff operation.
TEST_AND_RETURN_FALSE(puffin::PuffDiff(old_data_,
new_data_,
old_deflates_,
new_deflates_,
GetUsableCompressorTypes(),
temp_file.path(),
&puffdiff_delta));
TEST_AND_RETURN_FALSE(!puffdiff_delta.empty());
InstallOperation& operation = aop->op;
if (IsDiffOperationBetter(operation,
data_blob->size(),
puffdiff_delta.size(),
src_extents_.size())) {
operation.set_type(InstallOperation::PUFFDIFF);
*data_blob = std::move(puffdiff_delta);
}
}
return true;
}
bool BestDiffGenerator::TryZucchiniAndUpdateOperation(AnnotatedOperation* aop,
brillo::Blob* data_blob) {
// zip files are ignored for now. We expect puffin to perform better on those.
// Investigate whether puffin over zucchini yields better results on those.
if (!deflate_utils::IsFileExtensions(
aop->name,
{".ko",
".so",
".art",
".odex",
".vdex",
"<kernel>",
"<modem-partition>",
/*, ".capex",".jar", ".apk", ".apex"*/})) {
return true;
}
zucchini::ConstBufferView src_bytes(old_data_.data(), old_data_.size());
zucchini::ConstBufferView dst_bytes(new_data_.data(), new_data_.size());
zucchini::EnsemblePatchWriter patch_writer(src_bytes, dst_bytes);
auto status = zucchini::GenerateBuffer(src_bytes, dst_bytes, &patch_writer);
TEST_AND_RETURN_FALSE(status == zucchini::status::kStatusSuccess);
brillo::Blob zucchini_delta(patch_writer.SerializedSize());
patch_writer.SerializeInto({zucchini_delta.data(), zucchini_delta.size()});
// Compress the delta with brotli.
// TODO(197361113) support compressing the delta with different algorithms,
// similar to the usage in puffin.
brillo::Blob compressed_delta;
TEST_AND_RETURN_FALSE(puffin::BrotliEncode(
zucchini_delta.data(), zucchini_delta.size(), &compressed_delta));
InstallOperation& operation = aop->op;
if (IsDiffOperationBetter(operation,
data_blob->size(),
compressed_delta.size(),
src_extents_.size())) {
operation.set_type(InstallOperation::ZUCCHINI);
*data_blob = std::move(compressed_delta);
}
return true;
}
// This class encapsulates a file delta processing thread work. The
// processor computes the delta between the source and target files;
// and write the compressed delta to the blob.
class FileDeltaProcessor : public base::DelegateSimpleThread::Delegate {
public:
FileDeltaProcessor(const string& old_part,
const string& new_part,
const PayloadGenerationConfig& config,
const File& old_extents,
const File& new_extents,
const string& name,
ssize_t chunk_blocks,
BlobFileWriter* blob_file)
: old_part_(old_part),
new_part_(new_part),
config_(config),
old_extents_(old_extents),
new_extents_(new_extents),
new_extents_blocks_(utils::BlocksInExtents(new_extents.extents)),
name_(name),
chunk_blocks_(chunk_blocks),
blob_file_(blob_file) {}
bool operator>(const FileDeltaProcessor& other) const {
return new_extents_blocks_ > other.new_extents_blocks_;
}
~FileDeltaProcessor() override = default;
// Overrides DelegateSimpleThread::Delegate.
// Calculate the list of operations and write their corresponding deltas to
// the blob_file.
void Run() override;
// Merge each file processor's ops list to aops.
bool MergeOperation(vector<AnnotatedOperation>* aops);
private:
const string& old_part_; // NOLINT(runtime/member_string_references)
const string& new_part_; // NOLINT(runtime/member_string_references)
const PayloadGenerationConfig& config_;
// The block ranges of the old/new file within the src/tgt image
const File old_extents_;
const File new_extents_;
const size_t new_extents_blocks_;
const string name_;
// Block limit of one aop.
const ssize_t chunk_blocks_;
BlobFileWriter* blob_file_;
// The list of ops to reach the new file from the old file.
vector<AnnotatedOperation> file_aops_;
bool failed_ = false;
DISALLOW_COPY_AND_ASSIGN(FileDeltaProcessor);
};
void FileDeltaProcessor::Run() {
TEST_AND_RETURN(blob_file_ != nullptr);
base::TimeTicks start = base::TimeTicks::Now();
if (!DeltaReadFile(&file_aops_,
old_part_,
new_part_,
old_extents_,
new_extents_,
chunk_blocks_,
config_,
blob_file_)) {
LOG(ERROR) << "Failed to generate delta for " << name_ << " ("
<< new_extents_blocks_ << " blocks)";
failed_ = true;
return;
}
if (!ABGenerator::FragmentOperations(
config_.version, &file_aops_, new_part_, blob_file_)) {
LOG(ERROR) << "Failed to fragment operations for " << name_;
failed_ = true;
return;
}
LOG(INFO) << "Encoded file " << name_ << " (" << new_extents_blocks_
<< " blocks) in " << (base::TimeTicks::Now() - start);
}
bool FileDeltaProcessor::MergeOperation(vector<AnnotatedOperation>* aops) {
if (failed_)
return false;
std::move(file_aops_.begin(), file_aops_.end(), std::back_inserter(*aops));
return true;
}
FilesystemInterface::File GetOldFile(
const map<string, FilesystemInterface::File>& old_files_map,
const string& new_file_name) {
if (old_files_map.empty())
return {};
auto old_file_iter = old_files_map.find(new_file_name);
if (old_file_iter != old_files_map.end())
return old_file_iter->second;
// No old file matches the new file name. Use a similar file with the
// shortest levenshtein distance instead.
// This works great if the file has version number in it, but even for
// a completely new file, using a similar file can still help.
int min_distance =
LevenshteinDistance(new_file_name, old_files_map.begin()->first);
const FilesystemInterface::File* old_file = &old_files_map.begin()->second;
for (const auto& pair : old_files_map) {
int distance = LevenshteinDistance(new_file_name, pair.first);
if (distance < min_distance) {
min_distance = distance;
old_file = &pair.second;
}
}
LOG(INFO) << "Using " << old_file->name << " as source for " << new_file_name;
return *old_file;
}
std::vector<Extent> RemoveDuplicateBlocks(const std::vector<Extent>& extents) {
ExtentRanges extent_set;
std::vector<Extent> ret;
for (const auto& extent : extents) {
auto vec = FilterExtentRanges({extent}, extent_set);
ret.insert(ret.end(),
std::make_move_iterator(vec.begin()),
std::make_move_iterator(vec.end()));
extent_set.AddExtent(extent);
}
return ret;
}
bool DeltaReadPartition(vector<AnnotatedOperation>* aops,
const PartitionConfig& old_part,
const PartitionConfig& new_part,
ssize_t hard_chunk_blocks,
size_t soft_chunk_blocks,
const PayloadGenerationConfig& config,
BlobFileWriter* blob_file) {
const auto& version = config.version;
ExtentRanges old_visited_blocks;
ExtentRanges new_visited_blocks;
// If verity is enabled, mark those blocks as visited to skip generating
// operations for them.
if (version.minor >= kVerityMinorPayloadVersion &&
!new_part.verity.IsEmpty()) {
LOG(INFO) << "Skipping verity hash tree blocks: "
<< ExtentsToString({new_part.verity.hash_tree_extent});
new_visited_blocks.AddExtent(new_part.verity.hash_tree_extent);
LOG(INFO) << "Skipping verity FEC blocks: "
<< ExtentsToString({new_part.verity.fec_extent});
new_visited_blocks.AddExtent(new_part.verity.fec_extent);
}
const bool puffdiff_allowed =
config.OperationEnabled(InstallOperation::PUFFDIFF);
TEST_AND_RETURN_FALSE(new_part.fs_interface);
vector<FilesystemInterface::File> new_files;
TEST_AND_RETURN_FALSE(deflate_utils::PreprocessPartitionFiles(
new_part, &new_files, puffdiff_allowed));
ExtentRanges old_zero_blocks;
// Prematurely removing moved blocks will render compression info useless.
// Even if a single block inside a 100MB file is filtered out, the entire
// 100MB file can't be decompressed. In this case we will fallback to BSDIFF,
// which performs much worse than LZ4diff. It's better to let LZ4DIFF perform
// decompression, and let underlying BSDIFF to take care of moved blocks.
// TODO(b/206729162) Implement block filtering with compression block info
const auto no_compressed_files =
std::all_of(new_files.begin(), new_files.end(), [](const File& a) {
return a.compressed_file_info.blocks.empty();
});
if (!config.OperationEnabled(InstallOperation::LZ4DIFF_BSDIFF) ||
no_compressed_files) {
TEST_AND_RETURN_FALSE(DeltaMovedAndZeroBlocks(aops,
old_part.path,
new_part.path,
old_part.size / kBlockSize,
new_part.size / kBlockSize,
soft_chunk_blocks,
config,
blob_file,
&old_visited_blocks,
&new_visited_blocks,
&old_zero_blocks));
}
map<string, FilesystemInterface::File> old_files_map;
if (old_part.fs_interface) {
vector<FilesystemInterface::File> old_files;
TEST_AND_RETURN_FALSE(deflate_utils::PreprocessPartitionFiles(
old_part, &old_files, puffdiff_allowed));
for (const FilesystemInterface::File& file : old_files)
old_files_map[file.name] = file;
}
list<FileDeltaProcessor> file_delta_processors;
// The processing is very straightforward here, we generate operations for
// every file (and pseudo-file such as the metadata) in the new filesystem
// based on the file with the same name in the old filesystem, if any.
// Files with overlapping data blocks (like hardlinks or filesystems with tail
// packing or compression where the blocks store more than one file) are only
// generated once in the new image, but are also used only once from the old
// image due to some simplifications (see below).
for (const FilesystemInterface::File& new_file : new_files) {
// Ignore the files in the new filesystem without blocks. Symlinks with
// data blocks (for example, symlinks bigger than 60 bytes in ext2) are
// handled as normal files. We also ignore blocks that were already
// processed by a previous file.
vector<Extent> new_file_extents =
FilterExtentRanges(new_file.extents, new_visited_blocks);
new_visited_blocks.AddExtents(new_file_extents);
if (new_file_extents.empty())
continue;
FilesystemInterface::File old_file =
GetOldFile(old_files_map, new_file.name);
old_visited_blocks.AddExtents(old_file.extents);
// TODO(b/177104308) Filtering |new_file_extents| might confuse puffdiff, as
// we might filterout extents with deflate streams. PUFFDIFF is written with
// that in mind, so it will try to adapt to the filtered extents.
// Correctness is intact, but might yield larger patch sizes. From what we
// experimented, this has little impact on OTA size. Meanwhile, XOR ops
// depend on this. So filter out duplicate blocks from new file.
// TODO(b/194237829) |old_file.extents| is used instead of the de-duped
// |old_file_extents|. This is because zucchini diffing algorithm works
// better when given the full source file.
// Current logic:
// 1. src extent is completely unfiltered. It may contain
// duplicate blocks across files, within files, it may contain zero blocks,
// etc.
// 2. dst extent is completely filtered, no duplicate blocks or zero blocks
// whatsoever.
auto filtered_new_file = new_file;
filtered_new_file.extents = RemoveDuplicateBlocks(new_file_extents);
file_delta_processors.emplace_back(old_part.path,
new_part.path,
config,
std::move(old_file),
std::move(filtered_new_file),
new_file.name, // operation name
hard_chunk_blocks,
blob_file);
}
// Process all the blocks not included in any file. We provided all the unused
// blocks in the old partition as available data.
vector<Extent> new_unvisited = {
ExtentForRange(0, new_part.size / kBlockSize)};
new_unvisited = FilterExtentRanges(new_unvisited, new_visited_blocks);
if (!new_unvisited.empty()) {
vector<Extent> old_unvisited;
if (old_part.fs_interface) {
old_unvisited.push_back(ExtentForRange(0, old_part.size / kBlockSize));
old_unvisited = FilterExtentRanges(old_unvisited, old_visited_blocks);
}
LOG(INFO) << "Scanning " << utils::BlocksInExtents(new_unvisited)
<< " unwritten blocks using chunk size of " << soft_chunk_blocks
<< " blocks.";
// We use the soft_chunk_blocks limit for the <non-file-data> as we don't
// really know the structure of this data and we should not expect it to
// have redundancy between partitions.
File old_file;
old_file.extents = old_unvisited;
File new_file;
new_file.extents = RemoveDuplicateBlocks(new_unvisited);
file_delta_processors.emplace_back(old_part.path,
new_part.path,
config,
old_file,
new_file,
"<non-file-data>", // operation name
soft_chunk_blocks,
blob_file);
}
size_t max_threads = GetMaxThreads();
// Sort the files in descending order based on number of new blocks to make
// sure we start the largest ones first.
if (file_delta_processors.size() > max_threads) {
file_delta_processors.sort(std::greater<FileDeltaProcessor>());
}
base::DelegateSimpleThreadPool thread_pool("incremental-update-generator",
max_threads);
thread_pool.Start();
for (auto& processor : file_delta_processors) {
thread_pool.AddWork(&processor);
}
thread_pool.JoinAll();
for (auto& processor : file_delta_processors) {
TEST_AND_RETURN_FALSE(processor.MergeOperation(aops));
}
return true;
}
bool DeltaMovedAndZeroBlocks(vector<AnnotatedOperation>* aops,
const string& old_part,
const string& new_part,
size_t old_num_blocks,
size_t new_num_blocks,
ssize_t chunk_blocks,
const PayloadGenerationConfig& config,
BlobFileWriter* blob_file,
ExtentRanges* old_visited_blocks,
ExtentRanges* new_visited_blocks,
ExtentRanges* old_zero_blocks) {
vector<BlockMapping::BlockId> old_block_ids;
vector<BlockMapping::BlockId> new_block_ids;
TEST_AND_RETURN_FALSE(MapPartitionBlocks(old_part,
new_part,
old_num_blocks * kBlockSize,
new_num_blocks * kBlockSize,
kBlockSize,
&old_block_ids,
&new_block_ids));
// A mapping from the block_id to the list of block numbers with that block id
// in the old partition. This is used to lookup where in the old partition
// is a block from the new partition.
map<BlockMapping::BlockId, vector<uint64_t>> old_blocks_map;
for (uint64_t block = old_num_blocks; block-- > 0;) {
if (old_block_ids[block] != 0 && !old_visited_blocks->ContainsBlock(block))
old_blocks_map[old_block_ids[block]].push_back(block);
// Mark all zeroed blocks in the old image as "used" since it doesn't make
// any sense to spend I/O to read zeros from the source partition and more
// importantly, these could sometimes be blocks discarded in the SSD which
// would read non-zero values.
if (old_block_ids[block] == 0)
old_zero_blocks->AddBlock(block);
}
old_visited_blocks->AddRanges(*old_zero_blocks);
// The collection of blocks in the new partition with just zeros. This is a
// common case for free-space that's also problematic for bsdiff, so we want
// to optimize it using REPLACE_BZ operations. The blob for a REPLACE_BZ of
// just zeros is so small that it doesn't make sense to spend the I/O reading
// zeros from the old partition.
vector<Extent> new_zeros;
vector<Extent> old_identical_blocks;
vector<Extent> new_identical_blocks;
for (uint64_t block = 0; block < new_num_blocks; block++) {
// Only produce operations for blocks that were not yet visited.
if (new_visited_blocks->ContainsBlock(block))
continue;
if (new_block_ids[block] == 0) {
AppendBlockToExtents(&new_zeros, block);
continue;
}
auto old_blocks_map_it = old_blocks_map.find(new_block_ids[block]);
// Check if the block exists in the old partition at all.
if (old_blocks_map_it == old_blocks_map.end() ||
old_blocks_map_it->second.empty())
continue;
AppendBlockToExtents(&old_identical_blocks,
old_blocks_map_it->second.back());
AppendBlockToExtents(&new_identical_blocks, block);
}
if (chunk_blocks == -1)
chunk_blocks = new_num_blocks;
// Produce operations for the zero blocks split per output extent.
size_t num_ops = aops->size();
new_visited_blocks->AddExtents(new_zeros);
for (const Extent& extent : new_zeros) {
if (config.OperationEnabled(InstallOperation::ZERO)) {
for (uint64_t offset = 0; offset < extent.num_blocks();
offset += chunk_blocks) {
uint64_t num_blocks =
std::min(static_cast<uint64_t>(extent.num_blocks()) - offset,
static_cast<uint64_t>(chunk_blocks));
InstallOperation operation;
operation.set_type(InstallOperation::ZERO);
*(operation.add_dst_extents()) =
ExtentForRange(extent.start_block() + offset, num_blocks);
aops->push_back({.name = "<zeros>", .op = operation});
}
} else {
File old_file;
File new_file;
new_file.name = "<zeros>";
new_file.extents = {extent};
TEST_AND_RETURN_FALSE(DeltaReadFile(aops,
"",
new_part,
old_file, // old_extents
new_file, // new_extents
chunk_blocks,
config,
blob_file));
}
}
LOG(INFO) << "Produced " << (aops->size() - num_ops) << " operations for "
<< utils::BlocksInExtents(new_zeros) << " zeroed blocks";
// Produce MOVE/SOURCE_COPY operations for the moved blocks.
num_ops = aops->size();
uint64_t used_blocks = 0;
old_visited_blocks->AddExtents(old_identical_blocks);
new_visited_blocks->AddExtents(new_identical_blocks);
for (const Extent& extent : new_identical_blocks) {
// We split the operation at the extent boundary or when bigger than
// chunk_blocks.
for (uint64_t op_block_offset = 0; op_block_offset < extent.num_blocks();
op_block_offset += chunk_blocks) {
aops->emplace_back();
AnnotatedOperation* aop = &aops->back();
aop->name = "<identical-blocks>";
aop->op.set_type(InstallOperation::SOURCE_COPY);
uint64_t chunk_num_blocks =
std::min(static_cast<uint64_t>(extent.num_blocks()) - op_block_offset,
static_cast<uint64_t>(chunk_blocks));
// The current operation represents the move/copy operation for the
// sublist starting at |used_blocks| of length |chunk_num_blocks| where
// the src and dst are from |old_identical_blocks| and
// |new_identical_blocks| respectively.
StoreExtents(
ExtentsSublist(old_identical_blocks, used_blocks, chunk_num_blocks),
aop->op.mutable_src_extents());
Extent* op_dst_extent = aop->op.add_dst_extents();
op_dst_extent->set_start_block(extent.start_block() + op_block_offset);
op_dst_extent->set_num_blocks(chunk_num_blocks);
CHECK(
vector<Extent>{*op_dst_extent} == // NOLINT(whitespace/braces)
ExtentsSublist(new_identical_blocks, used_blocks, chunk_num_blocks));
used_blocks += chunk_num_blocks;
}
}
LOG(INFO) << "Produced " << (aops->size() - num_ops) << " operations for "
<< used_blocks << " identical blocks moved";
return true;
}
bool DeltaReadFile(std::vector<AnnotatedOperation>* aops,
const std::string& old_part,
const std::string& new_part,
const File& old_file,
const File& new_file,
ssize_t chunk_blocks,
const PayloadGenerationConfig& config,
BlobFileWriter* blob_file) {
const auto& old_extents = old_file.extents;
const auto& new_extents = new_file.extents;
const auto& name = new_file.name;
brillo::Blob data;
uint64_t total_blocks = utils::BlocksInExtents(new_extents);
if (chunk_blocks == 0) {
LOG(ERROR) << "Invalid number of chunk_blocks. Cannot be 0.";
return false;
}
if (chunk_blocks == -1)
chunk_blocks = total_blocks;
for (uint64_t block_offset = 0; block_offset < total_blocks;
block_offset += chunk_blocks) {
// Split the old/new file in the same chunks. Note that this could drop
// some information from the old file used for the new chunk. If the old
// file is smaller (or even empty when there's no old file) the chunk will
// also be empty.
vector<Extent> old_extents_chunk =
ExtentsSublist(old_extents, block_offset, chunk_blocks);
vector<Extent> new_extents_chunk =
ExtentsSublist(new_extents, block_offset, chunk_blocks);
NormalizeExtents(&old_extents_chunk);
NormalizeExtents(&new_extents_chunk);
// Now, insert into the list of operations.
AnnotatedOperation aop;
aop.name = new_file.name;
TEST_AND_RETURN_FALSE(ReadExtentsToDiff(old_part,
new_part,
old_extents_chunk,
new_extents_chunk,
old_file,
new_file,
config,
&data,
&aop));
// Check if the operation writes nothing.
if (aop.op.dst_extents_size() == 0) {
LOG(ERROR) << "Empty non-MOVE operation";
return false;
}
if (static_cast<uint64_t>(chunk_blocks) < total_blocks) {
aop.name = base::StringPrintf(
"%s:%" PRIu64, name.c_str(), block_offset / chunk_blocks);
}
// Write the data
TEST_AND_RETURN_FALSE(aop.SetOperationBlob(data, blob_file));
aops->emplace_back(aop);
}
return true;
}
bool GenerateBestFullOperation(const brillo::Blob& new_data,
const PayloadVersion& version,
brillo::Blob* out_blob,
InstallOperation::Type* out_type) {
if (new_data.empty())
return false;
if (version.OperationAllowed(InstallOperation::ZERO) &&
std::all_of(
new_data.begin(), new_data.end(), [](uint8_t x) { return x == 0; })) {
// The read buffer is all zeros, so produce a ZERO operation. No need to
// check other types of operations in this case.
*out_blob = brillo::Blob();
*out_type = InstallOperation::ZERO;
return true;
}
bool out_blob_set = false;
// Try compressing |new_data| with xz first.
if (version.OperationAllowed(InstallOperation::REPLACE_XZ)) {
brillo::Blob new_data_xz;
if (XzCompress(new_data, &new_data_xz) && !new_data_xz.empty()) {
*out_type = InstallOperation::REPLACE_XZ;
*out_blob = std::move(new_data_xz);
out_blob_set = true;
}
}
// Try compressing it with bzip2.
if (version.OperationAllowed(InstallOperation::REPLACE_BZ)) {
brillo::Blob new_data_bz;
// TODO(deymo): Implement some heuristic to determine if it is worth trying
// to compress the blob with bzip2 if we already have a good REPLACE_XZ.
if (BzipCompress(new_data, &new_data_bz) && !new_data_bz.empty() &&
(!out_blob_set || out_blob->size() > new_data_bz.size())) {
// A REPLACE_BZ is better or nothing else was set.
*out_type = InstallOperation::REPLACE_BZ;
*out_blob = std::move(new_data_bz);
out_blob_set = true;
}
}
// If nothing else worked or it was badly compressed we try a REPLACE.
if (!out_blob_set || out_blob->size() >= new_data.size()) {
*out_type = InstallOperation::REPLACE;
// This needs to make a copy of the data in the case bzip or xz didn't
// compress well, which is not the common case so the performance hit is
// low.
*out_blob = new_data;
}
return true;
}
// Decide which blocks are similar from bsdiff patch.
// Blocks included in out_op->xor_map will be converted to COW_XOR during OTA
// installation
bool PopulateXorOps(AnnotatedOperation* aop, const uint8_t* data, size_t size) {
bsdiff::BsdiffPatchReader patch_reader;
TEST_AND_RETURN_FALSE(patch_reader.Init(data, size));
ControlEntry entry;
size_t new_off = 0;
int64_t old_off = 0;
auto& xor_ops = aop->xor_ops;
size_t total_xor_blocks = 0;
const auto new_file_size =
utils::BlocksInExtents(aop->op.dst_extents()) * kBlockSize;
while (new_off < new_file_size) {
if (!patch_reader.ParseControlEntry(&entry)) {
LOG(ERROR)
<< "Exhausted bsdiff patch data before reaching end of new file. "
"Current position: "
<< new_off << " new file size: " << new_file_size;
return false;
}
if (old_off >= 0) {
auto dst_off_aligned = utils::RoundUp(new_off, kBlockSize);
const auto skip = dst_off_aligned - new_off;
auto src_off = old_off + skip;
const size_t chunk_size =
entry.diff_size - std::min(skip, entry.diff_size);
const auto xor_blocks = (chunk_size + kBlockSize / 2) / kBlockSize;
total_xor_blocks += xor_blocks;
// Append chunk_size/kBlockSize number of XOR blocks, subject to rounding
// rules: if decimal part of that division is >= 0.5, round up.
for (size_t i = 0; i < xor_blocks; i++) {
AppendXorBlock(
&xor_ops,
GetNthBlock(aop->op.src_extents(), src_off / kBlockSize),
GetNthBlock(aop->op.dst_extents(), dst_off_aligned / kBlockSize),
src_off % kBlockSize);
src_off += kBlockSize;
dst_off_aligned += kBlockSize;
}
}
old_off += entry.diff_size + entry.offset_increment;
new_off += entry.diff_size + entry.extra_size;
}
for (auto& op : xor_ops) {
CHECK_EQ(op.src_extent().num_blocks(), op.dst_extent().num_blocks());
// If |src_offset| is greater than 0, then we are reading 1
// extra block at the end of src_extent. This dependency must
// be honored during merge sequence generation, or we can end
// up with a corrupted device after merge.
if (op.src_offset() > 0) {
op.mutable_src_extent()->set_num_blocks(op.dst_extent().num_blocks() + 1);
}
}
if (xor_ops.size() > 0) {
// TODO(177104308) Filter out duplicate blocks in XOR op
LOG(INFO) << "Added " << total_xor_blocks << " XOR blocks, "
<< total_xor_blocks * 100.0f / new_off * kBlockSize
<< "% of blocks in this InstallOp are XOR";
}
return true;
}
bool ReadExtentsToDiff(const string& old_part,
const string& new_part,
const vector<Extent>& src_extents,
const vector<Extent>& dst_extents,
const File& old_file,
const File& new_file,
const PayloadGenerationConfig& config,
brillo::Blob* out_data,
AnnotatedOperation* out_op) {
const auto& version = config.version;
AnnotatedOperation& aop = *out_op;
InstallOperation& operation = aop.op;
// We read blocks from old_extents and write blocks to new_extents.
const uint64_t blocks_to_read = utils::BlocksInExtents(src_extents);
const uint64_t blocks_to_write = utils::BlocksInExtents(dst_extents);
// All operations have dst_extents.
StoreExtents(dst_extents, operation.mutable_dst_extents());
// Read in bytes from new data.
brillo::Blob new_data;
TEST_AND_RETURN_FALSE(utils::ReadExtents(new_part,
dst_extents,
&new_data,
kBlockSize * blocks_to_write,
kBlockSize));
TEST_AND_RETURN_FALSE(!new_data.empty());
// Data blob that will be written to delta file.
brillo::Blob data_blob;
// Try generating a full operation for the given new data, regardless of the
// old_data.
InstallOperation::Type op_type;
TEST_AND_RETURN_FALSE(
GenerateBestFullOperation(new_data, version, &data_blob, &op_type));
operation.set_type(op_type);
if (blocks_to_read > 0) {
brillo::Blob old_data;
// Read old data.
TEST_AND_RETURN_FALSE(utils::ReadExtents(old_part,
src_extents,
&old_data,
kBlockSize * blocks_to_read,
kBlockSize));
if (old_data == new_data) {
// No change in data.
operation.set_type(InstallOperation::SOURCE_COPY);
data_blob = brillo::Blob();
} else if (IsDiffOperationBetter(
operation, data_blob.size(), 0, src_extents.size())) {
// No point in trying diff if zero blob size diff operation is
// still worse than replace.
BestDiffGenerator best_diff_generator(old_data,
new_data,
src_extents,
dst_extents,
old_file,
new_file,
config);
if (!best_diff_generator.GenerateBestDiffOperation(&aop, &data_blob)) {
LOG(INFO) << "Failed to generate diff for " << new_file.name;
return false;
}
}
}
// WARNING: We always set legacy |src_length| and |dst_length| fields for
// BSDIFF. For SOURCE_BSDIFF we only set them for minor version 3 and
// lower. This is needed because we used to use these two parameters in the
// SOURCE_BSDIFF for minor version 3 and lower, but we do not need them
// anymore in higher minor versions. This means if we stop adding these
// parameters for those minor versions, the delta payloads will be invalid.
if (operation.type() == InstallOperation::SOURCE_BSDIFF &&
version.minor <= kOpSrcHashMinorPayloadVersion) {
operation.set_src_length(blocks_to_read * kBlockSize);
operation.set_dst_length(blocks_to_write * kBlockSize);
}
// Embed extents in the operation. Replace (all variants), zero and discard
// operations should not have source extents.
if (!IsNoSourceOperation(operation.type())) {
if (operation.src_extents_size() == 0) {
StoreExtents(src_extents, operation.mutable_src_extents());
}
} else {
operation.clear_src_extents();
}
*out_data = std::move(data_blob);
*out_op = aop;
return true;
}
bool IsAReplaceOperation(InstallOperation::Type op_type) {
return (op_type == InstallOperation::REPLACE ||
op_type == InstallOperation::REPLACE_BZ ||
op_type == InstallOperation::REPLACE_XZ);
}
bool IsNoSourceOperation(InstallOperation::Type op_type) {
return (IsAReplaceOperation(op_type) || op_type == InstallOperation::ZERO ||
op_type == InstallOperation::DISCARD);
}
bool InitializePartitionInfo(const PartitionConfig& part, PartitionInfo* info) {
info->set_size(part.size);
HashCalculator hasher;
TEST_AND_RETURN_FALSE(hasher.UpdateFile(part.path, part.size) ==
static_cast<off_t>(part.size));
TEST_AND_RETURN_FALSE(hasher.Finalize());
const brillo::Blob& hash = hasher.raw_hash();
info->set_hash(hash.data(), hash.size());
LOG(INFO) << part.path << ": size=" << part.size
<< " hash=" << HexEncode(hash);
return true;
}
bool CompareAopsByDestination(AnnotatedOperation first_aop,
AnnotatedOperation second_aop) {
// We want empty operations to be at the end of the payload.
if (!first_aop.op.dst_extents().size() || !second_aop.op.dst_extents().size())
return ((!first_aop.op.dst_extents().size()) <
(!second_aop.op.dst_extents().size()));
uint32_t first_dst_start = first_aop.op.dst_extents(0).start_block();
uint32_t second_dst_start = second_aop.op.dst_extents(0).start_block();
return first_dst_start < second_dst_start;
}
bool IsExtFilesystem(const string& device) {
brillo::Blob header;
// See include/linux/ext2_fs.h for more details on the structure. We obtain
// ext2 constants from ext2fs/ext2fs.h header but we don't link with the
// library.
if (!utils::ReadFileChunk(
device, 0, SUPERBLOCK_OFFSET + SUPERBLOCK_SIZE, &header) ||
header.size() < SUPERBLOCK_OFFSET + SUPERBLOCK_SIZE)
return false;
const uint8_t* superblock = header.data() + SUPERBLOCK_OFFSET;
// ext3_fs.h: ext3_super_block.s_blocks_count
uint32_t block_count =
*reinterpret_cast<const uint32_t*>(superblock + 1 * sizeof(int32_t));
// ext3_fs.h: ext3_super_block.s_log_block_size
uint32_t log_block_size =
*reinterpret_cast<const uint32_t*>(superblock + 6 * sizeof(int32_t));
// ext3_fs.h: ext3_super_block.s_magic
uint16_t magic =
*reinterpret_cast<const uint16_t*>(superblock + 14 * sizeof(int32_t));
block_count = le32toh(block_count);
log_block_size = le32toh(log_block_size) + EXT2_MIN_BLOCK_LOG_SIZE;
magic = le16toh(magic);
if (magic != EXT2_SUPER_MAGIC)
return false;
// Validation check the parameters.
TEST_AND_RETURN_FALSE(log_block_size >= EXT2_MIN_BLOCK_LOG_SIZE &&
log_block_size <= EXT2_MAX_BLOCK_LOG_SIZE);
TEST_AND_RETURN_FALSE(block_count > 0);
return true;
}
// Return the number of CPUs on the machine, and 4 threads in minimum.
size_t GetMaxThreads() {
return std::max(sysconf(_SC_NPROCESSORS_ONLN), 4L);
}
} // namespace diff_utils
} // namespace chromeos_update_engine
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