wantSize: 01234,
	}, {
		input: makeInput(FormatGNU, "1234",
			append(makeSparseStrings(sparseDatas{{0, 0}, {1, 1}}), []string{"", "blah"}...)...),
		wantMap:  sparseDatas{{0, 0}, {1, 1}},
		wantSize: 01234,
	}, {
		input: makeInput(FormatGNU, "3333",
			makeSparseStrings(sparseDatas{{0, 1}, {2, 1}, {4, 1}, {6, 1}})...),
		wantMap:  sparseDatas{{0, 1}, {2, 1}, {4, 1}, {6, 1}},
		wantSize: 03333,
	}, {

		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
		{seek: io.SeekStart, n: 5, want: "01234"},
		{seek: io.SeekCurrent, n: 5, want: "56789"},
		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
	}

	for i, tt := range tests {
		pos, err := r.Seek(tt.off, tt.seek)
		if err == nil && tt.seekerr != "" {