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());
      return total_bytes_transferred;
    }
    auto begin = data.begin();
    if (offset > pos) {
      // The block begins before the slice we're reading.
      begin += offset - pos;