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//
// Copyright (C) 2021 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 "lz4patch.h"
#include <endian.h>
#include <unistd.h>
#include <fcntl.h>
#include <algorithm>
#include <string_view>
#include <bsdiff/bspatch.h>
#include <bsdiff/memory_file.h>
#include <bsdiff/file.h>
#include <puffin/memory_stream.h>
#include "android-base/strings.h"
#include "lz4diff/lz4diff.h"
#include "lz4diff/lz4diff.pb.h"
#include "lz4diff_compress.h"
#include "lz4diff_format.h"
#include "puffin/puffpatch.h"
#include "update_engine/common/hash_calculator.h"
#include "update_engine/common/utils.h"
namespace chromeos_update_engine {
namespace {
template <typename T>
constexpr void BigEndianToHost(T& t) {
static_assert(std::is_integral_v<T>);
static_assert(sizeof(t) == 4 || sizeof(t) == 8 || sizeof(t) == 2);
if constexpr (sizeof(t) == 4) {
t = be32toh(t);
} else if constexpr (sizeof(t) == 8) {
t = be64toh(t);
} else if constexpr (sizeof(t) == 2) {
t = be16toh(t);
}
}
// In memory representation of an LZ4Diff patch, it's not marked as packed
// because parsing isn't as simple as reinterpret_cast<> any way.
struct Lz4diffPatch {
char magic[kLz4diffMagic.size()];
uint32_t version;
uint32_t pb_header_size; // size of protobuf message
Lz4diffHeader pb_header;
std::string_view inner_patch;
};
// Utility class to interact with puffin API. C++ does not have standard
// Read/Write trait. So everybody invent their own file descriptor wrapper.
class StringViewStream : public puffin::StreamInterface {
public:
~StringViewStream() override = default;
bool GetSize(uint64_t* size) const override {
*size = read_memory_.size();
return true;
}
bool GetOffset(uint64_t* offset) const override {
*offset = offset_;
return true;
}
bool Seek(uint64_t offset) override {
TEST_AND_RETURN_FALSE(open_);
uint64_t size;
GetSize(&size);
TEST_AND_RETURN_FALSE(offset <= size);
offset_ = offset;
return true;
}
bool Read(void* buffer, size_t length) override {
TEST_AND_RETURN_FALSE(open_);
TEST_AND_RETURN_FALSE(offset_ + length <= read_memory_.size());
memcpy(buffer, read_memory_.data() + offset_, length);
offset_ += length;
return true;
}
bool Write(const void* buffer, size_t length) override {
LOG(ERROR) << "Unsupported operation " << __FUNCTION__;
return false;
}
bool Close() override {
open_ = false;
return true;
}
constexpr StringViewStream(std::string_view read_memory)
: read_memory_(read_memory) {
CHECK(!read_memory.empty());
}
private:
// The memory buffer for reading.
std::string_view read_memory_;
// The current offset.
uint64_t offset_{};
bool open_{true};
};
bool ParseLz4DifffPatch(std::string_view patch_data, Lz4diffPatch* output) {
CHECK_NE(output, nullptr);
if (!android::base::StartsWith(patch_data, kLz4diffMagic)) {
LOG(ERROR) << "Invalid lz4diff magic: "
<< HexEncode(patch_data.substr(0, kLz4diffMagic.size()))
<< ", expected: " << HexEncode(kLz4diffMagic);
return false;
}
Lz4diffPatch& patch = *output;
std::memcpy(patch.magic, patch_data.data(), kLz4diffMagic.size());
std::memcpy(&patch.version,
patch_data.data() + kLz4diffMagic.size(),
sizeof(patch.version));
BigEndianToHost(patch.version);
if (patch.version != kLz4diffVersion) {
LOG(ERROR) << "Unsupported lz4diff version: " << patch.version
<< ", supported version: " << kLz4diffVersion;
return false;
}
std::memcpy(&patch.pb_header_size,
patch_data.data() + kLz4diffMagic.size() + sizeof(patch.version),
sizeof(patch.pb_header_size));
BigEndianToHost(patch.pb_header_size);
TEST_AND_RETURN_FALSE(patch.pb_header.ParseFromArray(
patch_data.data() + kLz4diffHeaderSize, patch.pb_header_size));
patch.inner_patch =
patch_data.substr(kLz4diffHeaderSize + patch.pb_header_size);
return true;
}
bool bspatch(std::string_view input_data,
std::string_view patch_data,
Blob* output) {
CHECK_NE(output, nullptr);
output->clear();
CHECK_GT(patch_data.size(), 0UL);
int err =
bsdiff::bspatch(reinterpret_cast<const uint8_t*>(input_data.data()),
input_data.size(),
reinterpret_cast<const uint8_t*>(patch_data.data()),
patch_data.size(),
[output](const uint8_t* data, size_t size) -> size_t {
output->insert(output->end(), data, data + size);
return size;
});
return err == 0;
}
bool puffpatch(std::string_view input_data,
std::string_view patch_data,
Blob* output) {
return puffin::PuffPatch(std::make_unique<StringViewStream>(input_data),
puffin::MemoryStream::CreateForWrite(output),
reinterpret_cast<const uint8_t*>(patch_data.data()),
patch_data.size());
}
std::vector<CompressedBlock> ToCompressedBlockVec(
const google::protobuf::RepeatedPtrField<CompressedBlockInfo>& rpf) {
std::vector<CompressedBlock> ret;
ret.reserve(rpf.size());
for (const auto& block : rpf) {
auto& info = ret.emplace_back();
info.compressed_length = block.compressed_length();
info.uncompressed_length = block.uncompressed_length();
info.uncompressed_offset = block.uncompressed_offset();
}
return ret;
}
bool HasPosfixPatches(const Lz4diffPatch& patch) {
for (const auto& info : patch.pb_header.dst_info().block_info()) {
if (!info.postfix_bspatch().empty()) {
return true;
}
}
return false;
}
size_t GetCompressedSize(
const google::protobuf::RepeatedPtrField<CompressedBlockInfo>& info) {
size_t compressed_size = 0;
for (const auto& block : info) {
compressed_size += block.compressed_length();
}
return compressed_size;
}
size_t GetDecompressedSize(
const google::protobuf::RepeatedPtrField<CompressedBlockInfo>& info) {
size_t decompressed_size = 0;
for (const auto& block : info) {
decompressed_size += block.uncompressed_length();
}
return decompressed_size;
}
bool ApplyInnerPatch(Blob decompressed_src,
const Lz4diffPatch& patch,
Blob* decompressed_dst) {
switch (patch.pb_header.inner_type()) {
case InnerPatchType::BSDIFF:
TEST_AND_RETURN_FALSE(bspatch(
ToStringView(decompressed_src), patch.inner_patch, decompressed_dst));
break;
case InnerPatchType::PUFFDIFF:
TEST_AND_RETURN_FALSE(puffpatch(
ToStringView(decompressed_src), patch.inner_patch, decompressed_dst));
break;
default:
LOG(ERROR) << "Unsupported patch type: " << patch.pb_header.inner_type();
return false;
}
return true;
}
// TODO(zhangkelvin) Rewrite this in C++ 20 coroutine once that's available.
// Hand coding CPS is not fun.
bool Lz4Patch(std::string_view src_data,
const Lz4diffPatch& patch,
const SinkFunc& sink) {
auto decompressed_src = TryDecompressBlob(
src_data,
ToCompressedBlockVec(patch.pb_header.src_info().block_info()),
patch.pb_header.src_info().zero_padding_enabled());
TEST_AND_RETURN_FALSE(!decompressed_src.empty());
Blob decompressed_dst;
const auto decompressed_dst_size =
GetDecompressedSize(patch.pb_header.dst_info().block_info());
decompressed_dst.reserve(decompressed_dst_size);
ApplyInnerPatch(std::move(decompressed_src), patch, &decompressed_dst);
if (!HasPosfixPatches(patch)) {
return TryCompressBlob(
ToStringView(decompressed_dst),
ToCompressedBlockVec(patch.pb_header.dst_info().block_info()),
patch.pb_header.dst_info().zero_padding_enabled(),
patch.pb_header.dst_info().algo(),
sink);
}
auto postfix_patcher =
[&sink,
block_idx = 0,
&dst_block_info = patch.pb_header.dst_info().block_info()](
const uint8_t* data, size_t size) mutable -> size_t {
if (block_idx >= dst_block_info.size()) {
return sink(data, size);
}
const auto& block_info = dst_block_info[block_idx];
TEST_EQ(size, block_info.compressed_length());
DEFER { block_idx++; };
if (block_info.postfix_bspatch().empty()) {
return sink(data, size);
}
if (!block_info.sha256_hash().empty()) {
Blob actual_hash;
TEST_AND_RETURN_FALSE(
HashCalculator::RawHashOfBytes(data, size, &actual_hash));
if (ToStringView(actual_hash) != block_info.sha256_hash()) {
LOG(ERROR) << "Block " << block_info
<< " is corrupted. This usually means the patch generator "
"used a different version of LZ4, or an incompatible LZ4 "
"patch generator was used, or LZ4 produces different "
"output on different platforms. Expected hash: "
<< HexEncode(block_info.sha256_hash())
<< ", actual hash: " << HexEncode(actual_hash);
return 0;
}
}
Blob fixed_block;
TEST_AND_RETURN_FALSE(
bspatch(std::string_view(reinterpret_cast<const char*>(data), size),
block_info.postfix_bspatch(),
&fixed_block));
return sink(fixed_block.data(), fixed_block.size());
};
return TryCompressBlob(
ToStringView(decompressed_dst),
ToCompressedBlockVec(patch.pb_header.dst_info().block_info()),
patch.pb_header.dst_info().zero_padding_enabled(),
patch.pb_header.dst_info().algo(),
postfix_patcher);
}
bool Lz4Patch(std::string_view src_data,
const Lz4diffPatch& patch,
Blob* output) {
Blob blob;
const auto output_size =
GetCompressedSize(patch.pb_header.dst_info().block_info());
blob.reserve(output_size);
TEST_AND_RETURN_FALSE(Lz4Patch(
src_data, patch, [&blob](const uint8_t* data, size_t size) -> size_t {
blob.insert(blob.end(), data, data + size);
return size;
}));
*output = std::move(blob);
return true;
}
} // namespace
bool Lz4Patch(std::string_view src_data,
std::string_view patch_data,
Blob* output) {
Lz4diffPatch patch;
TEST_AND_RETURN_FALSE(ParseLz4DifffPatch(patch_data, &patch));
return Lz4Patch(src_data, patch, output);
}
bool Lz4Patch(std::string_view src_data,
std::string_view patch_data,
const SinkFunc& sink) {
Lz4diffPatch patch;
TEST_AND_RETURN_FALSE(ParseLz4DifffPatch(patch_data, &patch));
return Lz4Patch(src_data, patch, sink);
}
bool Lz4Patch(const Blob& src_data, const Blob& patch_data, Blob* output) {
return Lz4Patch(ToStringView(src_data), ToStringView(patch_data), output);
}
std::ostream& operator<<(std::ostream& out, const CompressionAlgorithm& info) {
out << "Algo {type: " << info.Type_Name(info.type());
if (info.level() != 0) {
out << ", level: " << info.level();
}
out << "}";
return out;
}
std::ostream& operator<<(std::ostream& out, const CompressionInfo& info) {
out << "CompressionInfo {block_info: " << info.block_info()
<< ", algo: " << info.algo() << "}";
return out;
}
std::ostream& operator<<(std::ostream& out, const Lz4diffHeader& header) {
out << "Lz4diffHeader {src_info: " << header.src_info()
<< ", dst_info: " << header.dst_info() << "}";
return out;
}
} // namespace chromeos_update_engine