}

Status ModularFileSystem::NewReadOnlyMemoryRegionFromFile(
    const std::string& fname, TransactionToken* token,
    std::unique_ptr<ReadOnlyMemoryRegion>* result) {
  if (ops_->new_read_only_memory_region_from_file == nullptr)
    return errors::Unimplemented(tensorflow::strings::StrCat(
        "Filesystem for ", fname,
        " does not support NewReadOnlyMemoryRegionFromFile()"));

  ops->filesystem_ops->new_writable_file = tf_posix_filesystem::NewWritableFile;
  ops->filesystem_ops->new_appendable_file =
      tf_posix_filesystem::NewAppendableFile;
  ops->filesystem_ops->new_read_only_memory_region_from_file =
      tf_posix_filesystem::NewReadOnlyMemoryRegionFromFile;
  ops->filesystem_ops->create_dir = tf_posix_filesystem::CreateDir;
  ops->filesystem_ops->delete_file = tf_posix_filesystem::DeleteFile;

    return errors::FailedPrecondition(
        "Filesystem allows creation of writable files but no "
        "operations on them have been supplied.");

  if (ops->filesystem_ops->new_read_only_memory_region_from_file != nullptr &&
      ops->read_only_memory_region_ops == nullptr)
    return errors::FailedPrecondition(
        "Filesystem allows creation of readonly memory regions but no "

  ops->filesystem_ops->new_writable_file = tf_gcs_filesystem::NewWritableFile;
  ops->filesystem_ops->new_appendable_file =
      tf_gcs_filesystem::NewAppendableFile;
  ops->filesystem_ops->new_read_only_memory_region_from_file =
      tf_gcs_filesystem::NewReadOnlyMemoryRegionFromFile;
  ops->filesystem_ops->create_dir = tf_gcs_filesystem::CreateDir;
  ops->filesystem_ops->delete_file = tf_gcs_filesystem::DeleteFile;

  ///
  /// REQUIREMENTS: If plugins implement this, they must also provide a filled
  /// `TF_ReadOnlyMemoryRegionOps` table. See "REQUIRED OPERATIONS" above.
  void (*new_read_only_memory_region_from_file)(const TF_Filesystem* filesystem,
                                                const char* path,
                                                TF_ReadOnlyMemoryRegion* region,