wantSize  int64
		wantName  string
		wantErr   error
	}{{
		inputHdrs: nil,
		wantErr:   nil,
	}, {
		inputHdrs: map[string]string{
			paxGNUSparseNumBlocks: strconv.FormatInt(math.MaxInt64, 10),
			paxGNUSparseMap:       "0,1,2,3",
		},
		wantErr: ErrHeader,
	}, {
		inputHdrs: map[string]string{
			paxGNUSparseNumBlocks: "4\x00",
			paxGNUSparseMap:       "0,1,2,3",