buf := NewReader(r)
	allocs := testing.AllocsPerRun(100, func() {
		r.Seek(0, io.SeekStart)
		buf.Reset(r)

		_, err := buf.ReadString('\n')
		if err != nil {
			t.Fatal(err)
		}
	})
	if allocs != 1 {
		t.Errorf("Unexpected number of allocations, got %f, want 1", allocs)
	}
}

		r.File = make([]*File, 0, end.directoryRecords)
	}
	r.Comment = end.comment
	rs := io.NewSectionReader(rdr, 0, size)
	if _, err = rs.Seek(r.baseOffset+int64(end.directoryOffset), io.SeekStart); err != nil {
		return err
	}
	buf := bufio.NewReader(rs)

	// The count of files inside a zip is truncated to fit in a uint16.
	// Gloss over this by reading headers until we encounter

		want    string
		wantpos int64
		readerr error
		seekerr string
	}{
		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
		{seek: io.SeekStart, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},

	return nil
}

// Seek implements the [io.Seeker] interface.
func (r *Reader) Seek(offset int64, whence int) (int64, error) {
	r.prevRune = -1
	var abs int64
	switch whence {
	case io.SeekStart:
		abs = offset
	case io.SeekCurrent:
		abs = r.i + offset
	case io.SeekEnd:
		abs = int64(len(r.s)) + offset
	default:
		return 0, errors.New("bytes.Reader.Seek: invalid whence")
	}
	if abs < 0 {

pkg go/doc, type Example struct, Unordered bool
pkg io, const SeekCurrent = 1
pkg io, const SeekCurrent ideal-int
pkg io, const SeekEnd = 2
pkg io, const SeekEnd ideal-int
pkg io, const SeekStart = 0
pkg io, const SeekStart ideal-int
pkg math/big, method (*Float) GobDecode([]uint8) error
pkg math/big, method (*Float) GobEncode() ([]uint8, error)
pkg net, method (*Dialer) DialContext(context.Context, string, string) (Conn, error)