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323 lines
10 KiB
323 lines
10 KiB
// Copyright 2020 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#define PW_LOG_MODULE_NAME "KVS"
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#define PW_LOG_LEVEL PW_KVS_LOG_LEVEL
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#include "pw_kvs/internal/entry.h"
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#include <cinttypes>
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#include <cstring>
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#include "pw_kvs_private/config.h"
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#include "pw_log/log.h"
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#include "pw_status/try.h"
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namespace pw::kvs::internal {
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static_assert(
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kMaxFlashAlignment >= Entry::kMinAlignmentBytes,
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"Flash alignment is required to be at least Entry::kMinAlignmentBytes");
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constexpr size_t kWriteBufferSize =
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std::max(kMaxFlashAlignment, 4 * Entry::kMinAlignmentBytes);
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using std::byte;
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Status Entry::Read(FlashPartition& partition,
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Address address,
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const internal::EntryFormats& formats,
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Entry* entry) {
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EntryHeader header;
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PW_TRY(partition.Read(address, sizeof(header), &header));
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if (partition.AppearsErased(std::as_bytes(std::span(&header.magic, 1)))) {
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return Status::NotFound();
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}
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if (header.key_length_bytes > kMaxKeyLength) {
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return Status::DataLoss();
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}
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const EntryFormat* format = formats.Find(header.magic);
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if (format == nullptr) {
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PW_LOG_ERROR("Found corrupt magic: %" PRIx32 " at address %u",
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header.magic,
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unsigned(address));
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return Status::DataLoss();
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}
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*entry = Entry(&partition, address, *format, header);
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return OkStatus();
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}
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Status Entry::ReadKey(FlashPartition& partition,
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Address address,
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size_t key_length,
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char* key) {
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if (key_length == 0u || key_length > kMaxKeyLength) {
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return Status::DataLoss();
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}
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return partition.Read(address + sizeof(EntryHeader), key_length, key)
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.status();
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}
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Entry::Entry(FlashPartition& partition,
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Address address,
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const EntryFormat& format,
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Key key,
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std::span<const byte> value,
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uint16_t value_size_bytes,
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uint32_t transaction_id)
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: Entry(&partition,
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address,
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format,
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{.magic = format.magic,
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.checksum = 0,
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.alignment_units =
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alignment_bytes_to_units(partition.alignment_bytes()),
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.key_length_bytes = static_cast<uint8_t>(key.size()),
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.value_size_bytes = value_size_bytes,
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.transaction_id = transaction_id}) {
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if (checksum_algo_ != nullptr) {
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std::span<const byte> checksum = CalculateChecksum(key, value);
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std::memcpy(&header_.checksum,
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checksum.data(),
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std::min(checksum.size(), sizeof(header_.checksum)));
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}
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}
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StatusWithSize Entry::Write(Key key, std::span<const byte> value) const {
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FlashPartition::Output flash(partition(), address_);
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return AlignedWrite<kWriteBufferSize>(flash,
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alignment_bytes(),
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{std::as_bytes(std::span(&header_, 1)),
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std::as_bytes(std::span(key)),
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value});
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}
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Status Entry::Update(const EntryFormat& new_format,
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uint32_t new_transaction_id) {
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checksum_algo_ = new_format.checksum;
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header_.magic = new_format.magic;
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header_.alignment_units =
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alignment_bytes_to_units(partition_->alignment_bytes());
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header_.transaction_id = new_transaction_id;
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// If we could write the header last, we could avoid reading the entry twice
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// when moving an entry. However, to support alignments greater than the
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// header size, we first read the entire value to calculate the new checksum,
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// then write the full entry in WriteFrom.
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return CalculateChecksumFromFlash();
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}
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StatusWithSize Entry::Copy(Address new_address) const {
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PW_LOG_DEBUG("Copying entry from %u to %u as ID %" PRIu32,
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unsigned(address()),
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unsigned(new_address),
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transaction_id());
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FlashPartition::Output output(partition(), new_address);
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AlignedWriterBuffer<kWriteBufferSize> writer(alignment_bytes(), output);
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// Use this object's header rather than the header in flash of flash, since
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// this Entry may have been updated.
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PW_TRY_WITH_SIZE(writer.Write(&header_, sizeof(header_)));
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// Write only the key and value from the original entry.
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FlashPartition::Input input(partition(), address() + sizeof(EntryHeader));
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PW_TRY_WITH_SIZE(writer.Write(input, key_length() + value_size()));
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return writer.Flush();
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}
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StatusWithSize Entry::ReadValue(std::span<byte> buffer,
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size_t offset_bytes) const {
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if (offset_bytes > value_size()) {
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return StatusWithSize::OutOfRange();
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}
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const size_t remaining_bytes = value_size() - offset_bytes;
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const size_t read_size = std::min(buffer.size(), remaining_bytes);
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StatusWithSize result = partition().Read(
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address_ + sizeof(EntryHeader) + key_length() + offset_bytes,
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buffer.subspan(0, read_size));
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PW_TRY_WITH_SIZE(result);
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if (read_size != remaining_bytes) {
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return StatusWithSize::ResourceExhausted(read_size);
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}
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return StatusWithSize(read_size);
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}
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Status Entry::ValueMatches(std::span<const std::byte> value) const {
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if (value_size() != value.size_bytes()) {
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return Status::NotFound();
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}
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Address address = address_ + sizeof(EntryHeader) + key_length();
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Address end = address + value_size();
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const std::byte* value_ptr = value.data();
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std::array<std::byte, 2 * kMinAlignmentBytes> buffer;
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while (address < end) {
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const size_t read_size = std::min(size_t(end - address), buffer.size());
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PW_TRY(partition_->Read(address, std::span(buffer).first(read_size)));
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if (std::memcmp(buffer.data(), value_ptr, read_size) != 0) {
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return Status::NotFound();
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}
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address += read_size;
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value_ptr += read_size;
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}
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return OkStatus();
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}
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Status Entry::VerifyChecksum(Key key, std::span<const byte> value) const {
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if (checksum_algo_ == nullptr) {
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return header_.checksum == 0 ? OkStatus() : Status::DataLoss();
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}
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CalculateChecksum(key, value);
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return checksum_algo_->Verify(checksum_bytes());
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}
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Status Entry::VerifyChecksumInFlash() const {
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// Read the entire entry piece-by-piece into a small buffer. If the entry is
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// 32 B or less, only one read is required.
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union {
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EntryHeader header_to_verify;
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byte buffer[sizeof(EntryHeader) * 2];
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};
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size_t bytes_to_read = size();
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size_t read_size = std::min(sizeof(buffer), bytes_to_read);
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Address read_address = address_;
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// Read the first chunk, which includes the header, and compare the checksum.
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PW_TRY(partition().Read(read_address, read_size, buffer));
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if (header_to_verify.checksum != header_.checksum) {
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PW_LOG_ERROR("Expected checksum 0x%08" PRIx32 ", found 0x%08" PRIx32,
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header_.checksum,
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header_to_verify.checksum);
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return Status::DataLoss();
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}
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if (checksum_algo_ == nullptr) {
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return header_.checksum == 0 ? OkStatus() : Status::DataLoss();
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}
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// The checksum is calculated as if the header's checksum field were 0.
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header_to_verify.checksum = 0;
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checksum_algo_->Reset();
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while (true) {
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// Add the chunk in the buffer to the checksum.
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checksum_algo_->Update(buffer, read_size);
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bytes_to_read -= read_size;
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if (bytes_to_read == 0u) {
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break;
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}
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// Read the next chunk into the buffer.
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read_address += read_size;
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read_size = std::min(sizeof(buffer), bytes_to_read);
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PW_TRY(partition().Read(read_address, read_size, buffer));
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}
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checksum_algo_->Finish();
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return checksum_algo_->Verify(checksum_bytes());
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}
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void Entry::DebugLog() const {
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PW_LOG_DEBUG("Entry [%s]: ", deleted() ? "tombstone" : "present");
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PW_LOG_DEBUG(" Address = 0x%x", unsigned(address_));
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PW_LOG_DEBUG(" Transaction = %u", unsigned(transaction_id()));
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PW_LOG_DEBUG(" Magic = 0x%x", unsigned(magic()));
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PW_LOG_DEBUG(" Checksum = 0x%x", unsigned(header_.checksum));
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PW_LOG_DEBUG(" Key length = 0x%x", unsigned(key_length()));
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PW_LOG_DEBUG(" Value length = 0x%x", unsigned(value_size()));
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PW_LOG_DEBUG(" Entry size = 0x%x", unsigned(size()));
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PW_LOG_DEBUG(" Alignment = 0x%x", unsigned(alignment_bytes()));
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}
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std::span<const byte> Entry::CalculateChecksum(
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const Key key, std::span<const byte> value) const {
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checksum_algo_->Reset();
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{
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EntryHeader header_for_checksum = header_;
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header_for_checksum.checksum = 0;
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checksum_algo_->Update(&header_for_checksum, sizeof(header_for_checksum));
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checksum_algo_->Update(std::as_bytes(std::span(key)));
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checksum_algo_->Update(value);
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}
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AddPaddingBytesToChecksum();
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return checksum_algo_->Finish();
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}
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Status Entry::CalculateChecksumFromFlash() {
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header_.checksum = 0;
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if (checksum_algo_ == nullptr) {
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return OkStatus();
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}
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checksum_algo_->Reset();
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checksum_algo_->Update(&header_, sizeof(header_));
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Address address = address_ + sizeof(EntryHeader);
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// To handle alignment changes, do not read the padding. The padding is added
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// after checksumming the key and value from flash.
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const Address end = address_ + content_size();
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std::array<std::byte, 2 * kMinAlignmentBytes> buffer;
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while (address < end) {
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const size_t read_size = std::min(size_t(end - address), buffer.size());
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PW_TRY(partition_->Read(address, std::span(buffer).first(read_size)));
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checksum_algo_->Update(buffer.data(), read_size);
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address += read_size;
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}
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AddPaddingBytesToChecksum();
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std::span checksum = checksum_algo_->Finish();
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std::memcpy(&header_.checksum,
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checksum.data(),
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std::min(checksum.size(), sizeof(header_.checksum)));
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return OkStatus();
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}
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void Entry::AddPaddingBytesToChecksum() const {
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constexpr byte padding[kMinAlignmentBytes - 1] = {};
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size_t padding_to_add = Padding(content_size(), alignment_bytes());
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while (padding_to_add != 0u) {
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const size_t chunk_size = std::min(padding_to_add, sizeof(padding));
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checksum_algo_->Update(padding, chunk_size);
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padding_to_add -= chunk_size;
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}
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}
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} // namespace pw::kvs::internal
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