text: // Copyright 2017 The Fuchsia Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "garnet/lib/far/file_operations.h"
  
  #include <fcntl.h>
  
  #include "garnet/lib/far/alignment.h"
  #include "lib/fxl/files/unique_fd.h"
  
  namespace archive {
  
  bool CopyPathToFile(const char* src_path, int dst_fd, uint64_t length) {
    fxl::UniqueFD src_fd(open(src_path, O_RDONLY));
    if (!src_fd.is_valid()) {
      FXL_LOG(INFO) << "Failed to open " << src_path;
      return false;
    }
    return CopyFileToFile(src_fd.get(), dst_fd, length);
  }
  
  bool CopyFileToPath(int src_fd, const char* dst_path, uint64_t length) {
    fxl::UniqueFD dst_fd(open(dst_path, O_WRONLY | O_CREAT | O_TRUNC,
                              S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH));
    if (!dst_fd.is_valid())
      return false;
    return CopyFileToFile(src_fd, dst_fd.get(), length);
  }
  
  bool CopyFileToFile(int src_fd, int dst_fd, uint64_t length) {
    constexpr uint64_t kBufferSize = 64 * 1024;
    char buffer[kBufferSize];
    ssize_t actual = 0;
    for (uint64_t copied = 0; copied < length; copied += actual) {
      uint64_t requested =
          std::min(kBufferSize, static_cast<uint64_t>(length - copied));
      actual = read(src_fd, buffer, requested);
      if (actual <= 0)
        return false;
      if (!fxl::WriteFileDescriptor(dst_fd, buffer, actual))
        return false;
    }
    return true;
  }
  
  }  // namespace archive
  