}
	}
	return hdr, &tr.blk, p.err
}

// readOldGNUSparseMap reads the sparse map from the old GNU sparse format.
// The sparse map is stored in the tar header if it's small enough.
// If it's larger than four entries, then one or more extension headers are used
// to store the rest of the sparse map.
//
// The Header.Size does not reflect the size of any extended headers used.

	if r.columnNames == nil {
		r.columnNames = make([]string, len(csvRecord))
		for i := range csvRecord {
			r.columnNames[i] = fmt.Sprintf("_%v", i+1)
		}
	}

	// If no index map, add that.
	if r.nameIndexMap == nil {
		r.nameIndexMap = make(map[string]int64)
		for i := range r.columnNames {
			r.nameIndexMap[r.columnNames[i]] = int64(i)
		}
	}
	dstRec, ok := dst.(*Record)
	if !ok {
		dstRec = &Record{}
	}