Changed EncodeFEC to compute in incremental steps allowing OTA to be
paused during verity writes.
Test: tested incremental OTA on cuttelfish devices.
Bug: 243594791
Change-Id: I55179ab06fd22f10b246449e841d9b40204c6aaf
diff --git a/payload_consumer/verity_writer_android.cc b/payload_consumer/verity_writer_android.cc
index 91efa3e..479231d 100644
--- a/payload_consumer/verity_writer_android.cc
+++ b/payload_consumer/verity_writer_android.cc
@@ -20,6 +20,7 @@
#include <algorithm>
#include <memory>
+#include <utility>
#include <base/logging.h>
#include <base/posix/eintr_wrapper.h>
@@ -34,6 +35,121 @@
namespace chromeos_update_engine {
+bool IncrementalEncodeFEC::Init(const uint64_t _data_offset,
+ const uint64_t _data_size,
+ const uint64_t _fec_offset,
+ const uint64_t _fec_size,
+ const uint64_t _fec_roots,
+ const uint64_t _block_size,
+ const bool _verify_mode) {
+ current_step_ = EncodeFECStep::kInitFDStep;
+ data_offset_ = _data_offset;
+ data_size_ = _data_size;
+ fec_offset_ = _fec_offset;
+ fec_size_ = _fec_size;
+ fec_roots_ = _fec_roots;
+ block_size_ = _block_size;
+ verify_mode_ = _verify_mode;
+ current_round_ = 0;
+ // This is the N in RS(M, N), which is the number of bytes for each rs block.
+ rs_n_ = FEC_RSM - fec_roots_;
+ rs_char_.reset(init_rs_char(FEC_PARAMS(fec_roots_)));
+ rs_blocks_.resize(block_size_ * rs_n_);
+ buffer_.resize(block_size_, 0);
+ fec_.resize(block_size_ * fec_roots_);
+ fec_read_.resize(fec_.size());
+ TEST_AND_RETURN_FALSE(data_size_ % block_size_ == 0);
+ TEST_AND_RETURN_FALSE(fec_roots_ >= 0 && fec_roots_ < FEC_RSM);
+
+ num_rounds_ = utils::DivRoundUp(data_size_ / block_size_, rs_n_);
+ TEST_AND_RETURN_FALSE(num_rounds_ * fec_roots_ * block_size_ == fec_size_);
+ TEST_AND_RETURN_FALSE(rs_char_ != nullptr);
+ return true;
+}
+
+bool IncrementalEncodeFEC::Compute(FileDescriptor* _read_fd,
+ FileDescriptor* _write_fd) {
+ if (current_step_ == EncodeFECStep::kInitFDStep) {
+ read_fd_ = _read_fd;
+ write_fd_ = _write_fd;
+ cache_fd_.SetFD(write_fd_);
+ write_fd_ = &cache_fd_;
+ } else if (current_step_ == EncodeFECStep::kEncodeRoundStep) {
+ // Encodes |block_size| number of rs blocks each round so that we can read
+ // one block each time instead of 1 byte to increase random read
+ // performance. This uses about 1 MiB memory for 4K block size.
+ for (size_t j = 0; j < rs_n_; j++) {
+ uint64_t offset = fec_ecc_interleave(
+ current_round_ * rs_n_ * block_size_ + j, rs_n_, num_rounds_);
+ // Don't read past |data_size|, treat them as 0.
+ if (offset >= data_size_) {
+ std::fill(buffer_.begin(), buffer_.end(), 0);
+ } else {
+ ssize_t bytes_read = 0;
+ TEST_AND_RETURN_FALSE(utils::PReadAll(read_fd_,
+ buffer_.data(),
+ buffer_.size(),
+ data_offset_ + offset,
+ &bytes_read));
+ TEST_AND_RETURN_FALSE(bytes_read >= 0);
+ TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) ==
+ buffer_.size());
+ }
+ for (size_t k = 0; k < buffer_.size(); k++) {
+ rs_blocks_[k * rs_n_ + j] = buffer_[k];
+ }
+ }
+ for (size_t j = 0; j < block_size_; j++) {
+ // Encode [j * rs_n_ : (j + 1) * rs_n_) in |rs_blocks| and write
+ // |fec_roots| number of parity bytes to |j * fec_roots| in |fec|.
+ encode_rs_char(rs_char_.get(),
+ rs_blocks_.data() + j * rs_n_,
+ fec_.data() + j * fec_roots_);
+ }
+
+ if (verify_mode_) {
+ ssize_t bytes_read = 0;
+ TEST_AND_RETURN_FALSE(utils::PReadAll(read_fd_,
+ fec_read_.data(),
+ fec_read_.size(),
+ fec_offset_,
+ &bytes_read));
+ TEST_AND_RETURN_FALSE(bytes_read >= 0);
+ TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) ==
+ fec_read_.size());
+ TEST_AND_RETURN_FALSE(fec_ == fec_read_);
+ } else {
+ CHECK(write_fd_);
+ write_fd_->Seek(fec_offset_, SEEK_SET);
+ if (!utils::WriteAll(write_fd_, fec_.data(), fec_.size())) {
+ PLOG(ERROR) << "EncodeFEC write() failed";
+ return false;
+ }
+ }
+ fec_offset_ += fec_.size();
+ current_round_++;
+ } else if (current_step_ == EncodeFECStep::kWriteStep) {
+ write_fd_->Flush();
+ }
+ UpdateState();
+ return true;
+}
+// update the current state of EncodeFEC. Can be changed to have smaller steps
+void IncrementalEncodeFEC::UpdateState() {
+ if (current_step_ == EncodeFECStep::kInitFDStep) {
+ current_step_ = EncodeFECStep::kEncodeRoundStep;
+ } else if (current_step_ == EncodeFECStep::kEncodeRoundStep &&
+ current_round_ == num_rounds_) {
+ current_step_ = EncodeFECStep::kWriteStep;
+ } else if (current_step_ == EncodeFECStep::kWriteStep) {
+ current_step_ = EncodeFECStep::kComplete;
+ }
+}
+
+bool IncrementalEncodeFEC::Finished() const {
+ return current_step_ == EncodeFECStep::kComplete;
+}
+
namespace verity_writer {
std::unique_ptr<VerityWriterInterface> CreateVerityWriter() {
return std::make_unique<VerityWriterAndroid>();
@@ -42,7 +158,15 @@
bool VerityWriterAndroid::Init(const InstallPlan::Partition& partition) {
partition_ = &partition;
-
+ LOG(INFO) << "Initializing Incremental EncodeFEC";
+ TEST_AND_RETURN_FALSE(encodeFEC_.Init(partition_->fec_data_offset,
+ partition_->fec_data_size,
+ partition_->fec_offset,
+ partition_->fec_size,
+ partition_->fec_roots,
+ partition_->block_size,
+ false /* verify_mode */));
+ hash_tree_written_ = false;
if (partition_->hash_tree_size != 0) {
auto hash_function =
HashTreeBuilder::HashFunction(partition_->hash_tree_algorithm);
@@ -103,7 +227,6 @@
return true;
}
-
bool VerityWriterAndroid::Finalize(FileDescriptor* read_fd,
FileDescriptor* write_fd) {
const auto hash_tree_data_end =
@@ -145,6 +268,50 @@
return true;
}
+bool VerityWriterAndroid::IncrementalFinalize(FileDescriptor* read_fd,
+ FileDescriptor* write_fd) {
+ if (!hash_tree_written_) {
+ LOG(INFO) << "Completing prework in Finalize";
+ const auto hash_tree_data_end =
+ partition_->hash_tree_data_offset + partition_->hash_tree_data_size;
+ if (total_offset_ < hash_tree_data_end) {
+ LOG(ERROR) << "Read up to " << total_offset_
+ << " when we are expecting to read everything "
+ "before "
+ << hash_tree_data_end;
+ return false;
+ }
+ // All hash tree data blocks has been hashed, write hash tree to disk.
+ LOG(INFO) << "Writing verity hash tree to "
+ << partition_->readonly_target_path;
+ if (hash_tree_builder_) {
+ TEST_AND_RETURN_FALSE(hash_tree_builder_->BuildHashTree());
+ TEST_AND_RETURN_FALSE_ERRNO(
+ write_fd->Seek(partition_->hash_tree_offset, SEEK_SET));
+ auto success =
+ hash_tree_builder_->WriteHashTree([write_fd](auto data, auto size) {
+ return utils::WriteAll(write_fd, data, size);
+ });
+ // hashtree builder already prints error messages.
+ TEST_AND_RETURN_FALSE(success);
+ hash_tree_builder_.reset();
+ }
+ hash_tree_written_ = true;
+ if (partition_->fec_size != 0) {
+ LOG(INFO) << "Writing verity FEC to " << partition_->readonly_target_path;
+ }
+ }
+ if (partition_->fec_size != 0) {
+ TEST_AND_RETURN_FALSE(encodeFEC_.Compute(read_fd, write_fd));
+ }
+ return true;
+}
+bool VerityWriterAndroid::FECFinished() const {
+ if (encodeFEC_.Finished()) {
+ return true;
+ }
+ return false;
+}
bool VerityWriterAndroid::EncodeFEC(FileDescriptor* read_fd,
FileDescriptor* write_fd,
uint64_t data_offset,
@@ -156,7 +323,8 @@
bool verify_mode) {
TEST_AND_RETURN_FALSE(data_size % block_size == 0);
TEST_AND_RETURN_FALSE(fec_roots >= 0 && fec_roots < FEC_RSM);
- // This is the N in RS(M, N), which is the number of bytes for each rs block.
+ // This is the N in RS(M, N), which is the number of bytes for each rs
+ // block.
size_t rs_n = FEC_RSM - fec_roots;
uint64_t rounds = utils::DivRoundUp(data_size / block_size, rs_n);
TEST_AND_RETURN_FALSE(rounds * fec_roots * block_size == fec_size);
@@ -196,8 +364,8 @@
}
brillo::Blob fec(block_size * fec_roots);
for (size_t j = 0; j < block_size; j++) {
- // Encode [j * rs_n : (j + 1) * rs_n) in |rs_blocks| and write |fec_roots|
- // number of parity bytes to |j * fec_roots| in |fec|.
+ // Encode [j * rs_n : (j + 1) * rs_n) in |rs_blocks| and write
+ // |fec_roots| number of parity bytes to |j * fec_roots| in |fec|.
encode_rs_char(rs_char.get(),
rs_blocks.data() + j * rs_n,
fec.data() + j * fec_roots);