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);
  close(dst_fd);
  if (error_code != 0) {

  tensorflow::core::CppShapeInferenceResult::HandleData handle_data;
  if (!handle_data.ParseFromArray(proto, proto_len)) {
    status->status =
        absl::InvalidArgumentError("Couldn't deserialize HandleData proto");
    return;
  }
  DCHECK(handle_data.is_set());

  tensorflow::mutex_lock l(graph->mu);
  tensorflow::shape_inference::InferenceContext* ic =

  const char* filename;
  int fd;
} PosixFile;

static void Cleanup(TF_RandomAccessFile* file) {
  auto posix_file = static_cast<PosixFile*>(file->plugin_file);
  close(posix_file->fd);
  // This would be safe to free using `free` directly as it is only opaque.
  // However, it is better to be consistent everywhere.
  plugin_memory_free(const_cast<char*>(posix_file->filename));
  delete posix_file;
}

  // `gradient_checker` only works with model that returns only 1 tensor.
  // Although, `ops::SparseSoftmaxCrossEntropyWithLogits` returns 2 tensors, the
  // second tensor isn't needed for computing gradient so we could safely drop
  // it.
  outputs[0] = loss;
  backprop->Unref();
  return absl::OkStatus();
}

Status BiasAddModel(AbstractContext* ctx,
                    absl::Span<AbstractTensorHandle* const> inputs,

//
// Without this additional step, when there are schemes available but the user
// only requests schemes that don't exist, first instantiation of the test would
// filter out all the user provided schemes (as they are not registered) but
// subsequent instantiations would return all registered schemes (since the
// vector with the user provided schemes is cleared).
static std::vector<std::string>* GetSchemesFromUserOrEnv() {

      if (now - it->second->timestamp <= max_staleness_) {
        // The oldest block is not yet expired. Come back later.
        break;
      }
      // We need to make a copy of the filename here, since it could otherwise
      // be used within RemoveFile_Locked after `it` is deleted.
      RemoveFile_Locked(std::string(it->first.first));
    }
  }
}

void RamFileBlockCache::Flush() {
  absl::MutexLock lock(&mu_);

  bool UseFunction() const { return std::get<2>(GetParam()); }
};

TEST_P(CppGradients, TestIdentityNGrad) {
  // This test is interesting because the current implementation of GradientTape
  // would return [0, 1] whereas we use build_default_zeros_grads=false here
  // so we get back [nullptr, 1].

  AbstractTensorHandlePtr x1;
  {
    AbstractTensorHandle* x1_raw = nullptr;

  char buffer[BUFFER_SIZE];
  std::strncpy(buffer, "VALID", BUFFER_SIZE);
  TFE_OpSetAttrString(op, "padding", buffer, std::strlen(buffer));
  // Overwriting value in "buffer", should be fine since TFE_Op
  // shouldn't be holding on to it.
  std::strncpy(buffer, "NHWC", BUFFER_SIZE);
  TFE_OpSetAttrString(op, "data_format", buffer, std::strlen(buffer));

  TFE_OpSetAttrType(op, "T", TF_FLOAT);

  TF_FilesystemPluginInfo info;
  TF_InitPlugin(&info);
  Status status = filesystem_registration::RegisterFilesystemPluginImpl(&info);
  if (!status.ok()) {
    VLOG(0) << "Static POSIX filesystem could not be registered: " << status;
    return false;
  }
  return true;
}

// Perform the actual registration
static bool unused = StaticallyRegisterLocalFilesystems();

    TF_NewWritableFile(filepath.c_str(), &handle, s);
    ASSERT_TF_OK(s) << "NewWritableFile failed for " << filepath << ": "
                    << TF_Message(s);

    const char* data = "Hello, world!\n";
    TF_AppendWritableFile(handle, data, strlen(data), s);
    ASSERT_TF_OK(s) << "TF_AppendWritableFile failed to append data to file at "
                    << filepath << ": " << TF_Message(s);