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;
    if (copy_size < n && !consumed_buffer_to_eof) {
      gcs_file->buffer_start = offset + copy_size;
      gcs_file->buffer.resize(gcs_file->buffer_size);
      auto read_fill_buffer = gcs_file->read_fn(

      // 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
         << " at position " << pos << " with data size " << data.size();
      TF_SetStatus(status, TF_OUT_OF_RANGE, std::move(os).str().c_str());