<< ", offset = " << offset << ", n = " << n;
        } else {
          // Expect a partial read.
          EXPECT_EQ(got.size(), size - offset)
              << "block size = " << block_size << ", offset = " << offset
              << ", n = " << n;
        }
        // Verify the contents of the read.
        std::vector<char>::const_iterator begin = buf.begin() + offset;

    const auto& data = block->data;
    if (offset >= pos + data.size()) {
      // The requested offset is at or beyond the end of the file. This can
      // happen if `offset` is not block-aligned, and the read returns the last
      // block in the file, which does not extend all the way out to `offset`.
      std::stringstream os;
      os << "EOF at offset " << offset << " in file " << filename

                                     plugin_status.get());
  return StatusFromTF_Status(plugin_status.get());
}

Status ModularRandomAccessFile::Read(uint64 offset, size_t n,
                                     StringPiece* result, char* scratch) const {
  if (ops_->read == nullptr)
    return errors::Unimplemented(

  }
  int num_dims = dl_tensor->ndim;
  const int64_t* dims = dl_tensor->shape;
  void* data = dl_tensor->data;

  if (dl_tensor->byte_offset != 0) {
    status->status = tensorflow::errors::InvalidArgument(
        "Unsupported byte_offset (", dl_tensor->byte_offset,
        ") from DLPack, must be zero");
    return nullptr;
  }

  size_t total_bytes = dl_tensor->dtype.bits / 8;

  TF_TriState auto_parallel;
  TF_TriState memory_optimization;
  TF_TriState scoped_allocator_optimization;
} TP_OptimizerConfigs;

#define TP_OPTIMIZER_CONFIGS_STRUCT_SIZE \
  TF_OFFSET_OF_END(TP_OptimizerConfigs, scoped_allocator_optimization)

// Struct for Optimizer. Plugin authors must provide an optimize function.
// Creation and deletion functions are optional.
typedef struct TP_Optimizer {

    size_t copy_size = 0;
    if (offset < buffer_end && gcs_file->buffer_start) {
      copy_size = (std::min)(n, static_cast<size_t>(buffer_end - offset));
      memcpy(buffer,
             gcs_file->buffer.data() + (offset - gcs_file->buffer_start),
             copy_size);
    }
    bool consumed_buffer_to_eof =
        offset + copy_size >= buffer_end && gcs_file->buffer_end_is_past_eof;

  /// succeeded,
  ///    but the read returned a partial block, and the LRU cache contained a
  ///    block at a higher offset (indicating that the partial block should have
  ///    been a full block).
  /// 3) `TF_OUT_OF_RANGE` if the read from the remote filesystem succeeded, but
  ///    the file contents do not extend past `offset` and thus nothing was
  ///    placed in `out`.
  /// 4) `TF_OK` otherwise (i.e. the read succeeded, and at least one byte was

    // cross-platform, return type of `Read` is `int64_t`.
    int64_t r = int64_t{pread(posix_file->fd, dst, requested_read_length,
                              static_cast<off_t>(offset))};
    if (r > 0) {
      dst += r;
      offset += static_cast<uint64_t>(r);
      n -= r;  // safe as 0 < r <= n so n will never underflow
      read += r;
    } else if (r == 0) {

}

::testing::AssertionResult CompareSubString(int64_t offset, size_t length,
                                            absl::string_view result,
                                            size_t read) {
  // Result isn't a null-terminated string so we have to wrap it inside a
  // `string_view`
  if (length == read && content_view.substr(offset, length) ==
                            absl::string_view(result).substr(0, read))