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//
// Copyright (C) 2020 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_consumer/vabc_partition_writer.h"
#include <memory>
#include <string>
#include <vector>
#include <libsnapshot/cow_writer.h>
#include "update_engine/common/cow_operation_convert.h"
#include "update_engine/common/utils.h"
#include "update_engine/payload_consumer/extent_writer.h"
#include "update_engine/payload_consumer/file_descriptor.h"
#include "update_engine/payload_consumer/install_plan.h"
#include "update_engine/payload_consumer/partition_writer.h"
#include "update_engine/payload_consumer/snapshot_extent_writer.h"
namespace chromeos_update_engine {
// Expected layout of COW file:
// === Beginning of Cow Image ===
// All Source Copy Operations
// ========== Label 0 ==========
// Operation 0 in PartitionUpdate
// ========== Label 1 ==========
// Operation 1 in PartitionUpdate
// ========== label 2 ==========
// Operation 2 in PartitionUpdate
// ========== label 3 ==========
// .
// .
// .
// When resuming, pass |next_op_index_| as label to
// |InitializeWithAppend|.
// For example, suppose we finished writing SOURCE_COPY, and we finished writing
// operation 2 completely. Update is suspended when we are half way through
// operation 3.
// |cnext_op_index_| would be 3, so we pass 3 as
// label to |InitializeWithAppend|. The CowWriter will retain all data before
// label 3, Which contains all operation 2's data, but none of operation 3's
// data.
bool VABCPartitionWriter::Init(const InstallPlan* install_plan,
bool source_may_exist,
size_t next_op_index) {
TEST_AND_RETURN_FALSE(install_plan != nullptr);
TEST_AND_RETURN_FALSE(
OpenSourcePartition(install_plan->source_slot, source_may_exist));
std::optional<std::string> source_path;
if (!install_part_.source_path.empty()) {
// TODO(zhangkelvin) Make |source_path| a std::optional<std::string>
source_path = install_part_.source_path;
}
cow_writer_ = dynamic_control_->OpenCowWriter(
install_part_.name, source_path, install_plan->is_resume);
TEST_AND_RETURN_FALSE(cow_writer_ != nullptr);
// ===== Resume case handling code goes here ====
// It is possible that the SOURCE_COPY are already written but
// |next_op_index_| is still 0. In this case we discard previously written
// SOURCE_COPY, and start over.
if (install_plan->is_resume && next_op_index > 0) {
LOG(INFO) << "Resuming update on partition `"
<< partition_update_.partition_name() << "` op index "
<< next_op_index;
TEST_AND_RETURN_FALSE(cow_writer_->InitializeAppend(next_op_index));
return true;
} else {
TEST_AND_RETURN_FALSE(cow_writer_->Initialize());
}
// ==============================================
// TODO(zhangkelvin) Rewrite this in C++20 coroutine once that's available.
auto converted = ConvertToCowOperations(partition_update_.operations(),
partition_update_.merge_operations());
WriteAllCowOps(block_size_, converted, cow_writer_.get(), source_fd_);
return true;
}
bool VABCPartitionWriter::WriteAllCowOps(
size_t block_size,
const std::vector<CowOperation>& converted,
android::snapshot::ICowWriter* cow_writer,
FileDescriptorPtr source_fd) {
std::vector<uint8_t> buffer(block_size);
for (const auto& cow_op : converted) {
switch (cow_op.op) {
case CowOperation::CowCopy:
if (cow_op.src_block == cow_op.dst_block) {
continue;
}
TEST_AND_RETURN_FALSE(
cow_writer->AddCopy(cow_op.dst_block, cow_op.src_block));
break;
case CowOperation::CowReplace:
ssize_t bytes_read = 0;
TEST_AND_RETURN_FALSE(utils::ReadAll(source_fd,
buffer.data(),
block_size,
cow_op.src_block * block_size,
&bytes_read));
if (bytes_read <= 0 || static_cast<size_t>(bytes_read) != block_size) {
LOG(ERROR) << "source_fd->Read failed: " << bytes_read;
return false;
}
TEST_AND_RETURN_FALSE(cow_writer->AddRawBlocks(
cow_op.dst_block, buffer.data(), block_size));
break;
}
}
return true;
}
std::unique_ptr<ExtentWriter> VABCPartitionWriter::CreateBaseExtentWriter() {
return std::make_unique<SnapshotExtentWriter>(cow_writer_.get());
}
[[nodiscard]] bool VABCPartitionWriter::PerformZeroOrDiscardOperation(
const InstallOperation& operation) {
for (const auto& extent : operation.dst_extents()) {
TEST_AND_RETURN_FALSE(
cow_writer_->AddZeroBlocks(extent.start_block(), extent.num_blocks()));
}
return true;
}
[[nodiscard]] bool VABCPartitionWriter::PerformSourceCopyOperation(
const InstallOperation& operation, ErrorCode* error) {
// TODO(zhangkelvin) Probably just ignore SOURCE_COPY? They should be taken
// care of during Init();
return true;
}
void VABCPartitionWriter::CheckpointUpdateProgress(size_t next_op_index) {
// No need to call fsync/sync, as CowWriter flushes after a label is added
// added.
// if cow_writer_ failed, that means Init() failed. This function shouldn't be
// called if Init() fails.
TEST_AND_RETURN(cow_writer_ != nullptr);
cow_writer_->AddLabel(next_op_index);
}
[[nodiscard]] bool VABCPartitionWriter::FinishedInstallOps() {
// Add a hardcoded magic label to indicate end of all install ops. This label
// is needed by filesystem verification, don't remove.
TEST_AND_RETURN_FALSE(cow_writer_ != nullptr);
return cow_writer_->AddLabel(kEndOfInstallLabel);
}
VABCPartitionWriter::~VABCPartitionWriter() {
if (cow_writer_) {
cow_writer_->Finalize();
}
}
} // namespace chromeos_update_engine
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