//   If file exists, truncate its size to 0.
  int dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, open_mode);
  if (dst_fd < 0) {
    close(src_fd);
    return -1;
  }

  // Both files have been opened, do the transfer.
  // Since errno would be overridden by `close` below, save it here.
  int error_code = 0;
  if (CopyFileContents(dst_fd, src_fd, size) < 0) error_code = errno;

  close(src_fd);

    return;
  } else if (S_ISDIR(st.st_mode)) {
    TF_SetStatus(status, TF_FAILED_PRECONDITION, "source path is a directory");
    return;
  }

  // Both `src` and `dst` point to files here. Delegate to helper.
  if (TransferFileContents(src, dst, st.st_mode, st.st_size) < 0)
    TF_SetStatusFromIOError(status, errno, dst);
  else
    TF_SetStatus(status, TF_OK, "");
}

                                   TransactionToken* token,
                                   std::vector<Status>* status) {
  if (ops_->paths_exist == nullptr)
    return FileSystem::FilesExist(files, token, status);

  std::vector<char*> translated_names;
  translated_names.reserve(files.size());
  for (int i = 0; i < files.size(); i++)

  if (!status.ok()) GTEST_SKIP() << "CreateDir() not supported: " << status;

  int64_t undeleted_files = 0;
  int64_t undeleted_dirs = 0;
  status = env_->DeleteRecursively(dirpath, &undeleted_files, &undeleted_dirs);
  EXPECT_PRED2(UnimplementedOrReturnsCode, status, Code::OK);
  EXPECT_EQ(undeleted_files, 0);
  EXPECT_EQ(undeleted_dirs, 0);
}

TEST_P(ModularFileSystemTest, TestDeleteRecursivelyNotEmpty) {

      c = toupper(c);
    }
    memset(buffer, c, n);
    TF_SetStatus(status, TF_OK, "");
    return n;
  };
  // This cache has space for 4 blocks; we'll read from two files.
  const size_t n = 3;
  tf_gcs_filesystem::RamFileBlockCache cache(8, 32, 0, fetcher);
  std::vector<char> out;
  std::vector<char> a(n, 'a');
  std::vector<char> b(n, 'b');
  std::vector<char> A(n, 'A');

  if (ops == nullptr) {
    // We allow filesystems where files can only be written to (from TF code)
    return OkStatus();
  }

  if (ops->cleanup == nullptr)
    return errors::FailedPrecondition(
        "Trying to register filesystem without `cleanup` operation on random "
        "access files");

  return OkStatus();
}

                       uint64_t* undeleted_files, uint64_t* undeleted_dirs,
                       TF_Status* status) {
  if (!undeleted_files || !undeleted_dirs)
    return TF_SetStatus(
        status, TF_INTERNAL,
        "'undeleted_files' and 'undeleted_dirs' cannot be nullptr.");
  *undeleted_files = 0;
  *undeleted_dirs = 0;
  if (!IsDirectory(filesystem, path, status)) {