if len(h.SparseHoles) > 0 || h.Typeflag == TypeGNUSparse {
			if isHeaderOnlyType(h.Typeflag) {
				return FormatUnknown, nil, headerError{"header-only type cannot be sparse"}
			}
			if !validateSparseEntries(h.SparseHoles, h.Size) {
				return FormatUnknown, nil, headerError{"invalid sparse holes"}
			}
			if h.Typeflag == TypeGNUSparse {
				whyOnlyGNU = "only GNU supports TypeGNUSparse"
				format.mayOnlyBe(FormatGNU)
			} else {

		// See https://golang.org/issue/22735
		/*
			}, {
				file: "testdata/gnu-nil-sparse-data.tar",
				tests: []testFnc{
					testHeader{Header{
						Typeflag:    TypeGNUSparse,
						Name:        "sparse.db",
						Size:        1000,
						SparseHoles: []sparseEntry{{Offset: 1000, Length: 0}},
					}, nil},
					testWrite{strings.Repeat("0123456789", 100), 1000, nil},
					testClose{},

		headers: []*Header{{
			Name:     "sparse.db",
			Typeflag: TypeGNUSparse,
			Size:     1000,
			ModTime:  time.Unix(0, 0),
			Format:   FormatGNU,
		}},
	}, {
		// Generated by Go, works on BSD tar v3.1.2 and GNU tar v.1.27.1.
		file: "testdata/gnu-nil-sparse-hole.tar",
		headers: []*Header{{
			Name:     "sparse.db",
			Typeflag: TypeGNUSparse,
			Size:     1000,
			ModTime:  time.Unix(0, 0),

// and sets the curr reader appropriately.
func (tr *Reader) handleSparseFile(hdr *Header, rawHdr *block) error {
	var spd sparseDatas
	var err error
	if hdr.Typeflag == TypeGNUSparse {
		spd, err = tr.readOldGNUSparseMap(hdr, rawHdr)
	} else {
		spd, err = tr.readGNUSparsePAXHeaders(hdr)
	}

	// If sp is non-nil, then this is a sparse file.
	// Note that it is possible for len(sp) == 0.