// Copyright 2026 Google LLC
//
// 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 "utils/riegeli.h"

#include <algorithm>
#include <cstring>
#include <string>

#include "riegeli/base/arithmetic.h"
#include "riegeli/bytes/reader.h"

namespace credentio {

bool ReadNullTerminatedString(riegeli::Reader& reader, size_t max_length,
                              std::string& output) {
  reader.Pull(max_length);
  if (reader.available() == 0) {
    // The data ends. Avoid undefined behavior in `std::memchr(nullptr, _, _)`
    // if `reader.cursor() == nullptr`.
    return false;
  }
  const char* const terminator = static_cast<const char*>(std::memchr(
      reader.cursor(), '\0', std::min(reader.available(), max_length)));
  if (terminator == nullptr) {
    // No null terminator found within the max_length.
    return false;
  }

  size_t length = riegeli::PtrDistance(reader.cursor(), terminator);
  if (!reader.Read(length, output)) {
    // Failed to read the string.
    return false;
  }
  if (!reader.Skip(1)) {
    // Failed to skip the null terminator.
    return false;
  }
  return true;
}

}  // namespace credentio