file_reader.cpp

/*
 * This file is a part of the CaosDB Project.
 * Copyright (C) 2021 Timm Fitschen <t.fitschen@indiscale.com>
 * Copyright (C) 2021 IndiScale GmbH <info@indiscale.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 *
 *********************************************************************************
 *
 * This is derived work which is heavily based on
 * https://github.com/NeiRo21/grpcpp-bidi-streaming, Commit
 * cd9cb78e5d6d72806c2ec4c703e5e856b223dc96, Aug 10, 2020
 *
 * The orginal work is licensed as
 *
 * > MIT License
 * >
 * > Copyright (c) 2019 NeiRo21
 * >
 * > Permission is hereby granted, free of charge, to any person obtaining a
 * > copy of this software and associated documentation files (the "Software"),
 * > to deal in the Software without restriction, including without limitation
 * > the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * > and/or sell copies of the Software, and to permit persons to whom the
 * > Software is furnished to do so, subject to the following conditions:
 * >
 * > The above copyright notice and this permission notice shall be included in
 * > all copies or substantial portions of the Software.
 * >
 * > THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * > IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * > FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * > AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * > LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * > FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * > DEALINGS IN THE SOFTWARE.
 */
#include "caosdb/file_transmission/file_reader.h"
#include "caosdb/file_transmission/file_error.h" // for FileIOError
#include <boost/filesystem/path.hpp>             // for path
#include <utility>                               // for move

namespace caosdb::transaction {

FileReader::FileReader(boost::filesystem::path filename)
  : filename_(std::move(filename)), size_(0) {
  this->openFile();
}

void FileReader::openFile() {
  stream_.open(filename_, std::ios::binary | std::ios::ate);
  if (!stream_) {
    throw FileIOError("Can't open file for reading: " + filename_.string());
  }

  auto size = stream_.tellg();
  stream_.seekg(0);
  if (size > 0) {
    size_ = static_cast<decltype(size_)>(size);
  }
}

std::size_t FileReader::read(std::string &buffer) {
  std::size_t bytesRead = 0;

  if (!stream_.eof()) {
    auto bufferSize = buffer.size();
    if (bufferSize > 0) {
      // TODO(henrik): fix nolint
      if (!stream_.read(&buffer[0], bufferSize)) { // NOLINT
        throw FileIOError("Can't read file: " + filename_.string());
      }

      bytesRead = static_cast<std::size_t>(stream_.gcount());
    }
  }

  return bytesRead;
}

} // namespace caosdb::transaction