// Copyright 2020 The Pigweed Authors
//
// 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
//
//     https://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 "pw_kvs/checksum.h"

#include <cstring>

namespace pw::kvs {

using std::byte;

Status ChecksumAlgorithm::Verify(std::span<const byte> checksum) const {
  if (checksum.size() < size_bytes()) {
    return Status::InvalidArgument();
  }
  if (state_.empty()) {
    // Special case: state_.data is a nullptr, so calling std::memcmp would be
    // undefined behavior.
    return OkStatus();
  }
  if (std::memcmp(state_.data(), checksum.data(), size_bytes()) != 0) {
    return Status::DataLoss();
  }
  return OkStatus();
}

}  // namespace pw::kvs