func fileValidity(now time.Time) (int, error) {
	// If there is no 'weekends' file create it and initialize it
	// to a random day of the week. There is a short interval for
	// a race.
	weekends := filepath.Join(telemetry.Default.LocalDir(), "weekends")
	day := fmt.Sprintf("%d\n", rand.Intn(7))
	if _, err := os.ReadFile(weekends); err != nil {

today's date
L787:                    if (calendar[row][col].isSame(new Date(), "day"))
L788:                        classes.push('today');
L789:
L790:                    //highlight weekends
L791:                    if (calendar[row][col].isoWeekday() > 5)
L792:                        classes.push('weekend');
L793:
L794:                    //grey out the dates in other months displayed at beginning and end of this calendar
L795:                    if (calendar[row][col].month() != calendar[1][1].month())
...

	rf(t, ws, []byte{})

	// seeks and reads.
	sk(t, ws, 1, io.SeekStart)
	rf(t, ws, []byte{2, 7})
	sk(t, ws, -2, io.SeekCurrent)
	rf(t, ws, []byte{2, 7})
	sk(t, ws, -4, io.SeekEnd)
	rf(t, ws, []byte{2, 7})
	off := sk(t, ws, 0, io.SeekEnd)
	sk(t, ws, off, io.SeekStart)

	// seek back and overwrite
	sk(t, ws, 1, io.SeekStart)
	wf(t, ws, []byte{9, 11})
	wpex = []byte{1, 9, 11, 8, 9}
	sleq(t, ws.BytesWritten(), wpex)

	return syscall.Read(int(fd), buf)
}

func closefd(fd uintptr) {
	syscall.Close(int(fd))
}

func preadn(fd uintptr, buf []byte, off int) error {
	whence := seekStart
	if off < 0 {
		whence = seekEnd
	}
	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
		return err
	}
	for len(buf) > 0 {
		m, err := syscall.Read(int(fd), buf)
		if m <= 0 {
			if err == nil {

	fi, err := f.Stat()
	if err != nil {
		return nil, false, err
	}
	size := fi.Size()
	if size == 0 {
		return nil, false, nil
	}
	if size < max {
		max = size
	}
	offset, err := f.Seek(-max, io.SeekEnd)
	if err != nil {
		return nil, false, err
	}
	data, err := io.ReadAll(f)
	return data, offset > 0, err

}

func closefd(fd uintptr) {
	syscall.Close(syscall.Handle(fd))
}

func preadn(fd uintptr, buf []byte, off int) error {
	whence := seekStart
	if off < 0 {
		whence = seekEnd
	}
	if _, err := syscall.Seek(syscall.Handle(fd), int64(off), whence); err != nil {
		return err
	}
	for len(buf) > 0 {
		m, err := syscall.Read(syscall.Handle(fd), buf)
		if m <= 0 {
			if err == nil {

	return syscall.Read(int(fd), buf)
}

func closefd(fd uintptr) {
	syscall.Close(int(fd))
}

func preadn(fd uintptr, buf []byte, off int) error {
	whence := seekStart
	if off < 0 {
		whence = seekEnd
	}
	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
		return err
	}
	for len(buf) > 0 {
		m, err := syscall.Read(int(fd), buf)
		if m <= 0 {
			if err == nil {

		return 0, err
	}

	if n <= 0 { // We don't know the size of the file so infer it.
		// Find the number of bytes offset from curpos until the end of the file.
		n, err = syscall.Seek(o.handle, -curpos, io.SeekEnd)
		if err != nil {
			return
		}
		// Now seek back to the original position.
		if _, err = syscall.Seek(o.handle, curpos, io.SeekStart); err != nil {
			return
		}
	}

	if r.fileView == nil {
		return r.rdr.MustSeek(offset, whence), nil
	}
	switch whence {
	case io.SeekStart:
		r.off = offset
		return offset, nil
	case io.SeekCurrent:
		return r.off, nil
	case io.SeekEnd:
		r.off = int64(len(r.fileView)) + offset
		return r.off, nil
	}
	panic("other modes not implemented")

func (r *readSeekerFromReader) Seek(offset int64, whence int) (int64, error) {
	var newOffset int64
	switch whence {
	case io.SeekStart:
		newOffset = offset
	case io.SeekCurrent:
		newOffset = r.offset + offset
	case io.SeekEnd:
		newOffset = r.size + offset
	default:
		return 0, os.ErrInvalid
	}

	switch {
	case newOffset == r.offset:
		return newOffset, nil

	case newOffset < 0, newOffset > r.size:
		return 0, os.ErrInvalid