1//go:build !sqlite3_flock
  2
  3package vfs
  4
  5import (
  6	"io"
  7	"os"
  8	"runtime"
  9	"time"
 10
 11	"golang.org/x/sys/unix"
 12)
 13
 14const (
 15	// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
 16	_F_OFD_SETLK         = 90
 17	_F_OFD_SETLKW        = 91
 18	_F_OFD_SETLKWTIMEOUT = 93
 19)
 20
 21type flocktimeout_t struct {
 22	fl      unix.Flock_t
 23	timeout unix.Timespec
 24}
 25
 26func osSync(file *os.File, fullsync, _ /*dataonly*/ bool) error {
 27	if fullsync {
 28		return file.Sync()
 29	}
 30	for {
 31		err := unix.Fsync(int(file.Fd()))
 32		if err != unix.EINTR {
 33			return err
 34		}
 35	}
 36}
 37
 38func osAllocate(file *os.File, size int64) error {
 39	off, err := file.Seek(0, io.SeekEnd)
 40	if err != nil {
 41		return err
 42	}
 43	if size <= off {
 44		return nil
 45	}
 46
 47	store := unix.Fstore_t{
 48		Flags:   unix.F_ALLOCATEALL | unix.F_ALLOCATECONTIG,
 49		Posmode: unix.F_PEOFPOSMODE,
 50		Offset:  0,
 51		Length:  size - off,
 52	}
 53
 54	// Try to get a continuous chunk of disk space.
 55	err = unix.FcntlFstore(file.Fd(), unix.F_PREALLOCATE, &store)
 56	if err != nil {
 57		// OK, perhaps we are too fragmented, allocate non-continuous.
 58		store.Flags = unix.F_ALLOCATEALL
 59		unix.FcntlFstore(file.Fd(), unix.F_PREALLOCATE, &store)
 60	}
 61	return file.Truncate(size)
 62}
 63
 64func osReadLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
 65	return osLock(file, unix.F_RDLCK, start, len, timeout, _IOERR_RDLOCK)
 66}
 67
 68func osWriteLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
 69	return osLock(file, unix.F_WRLCK, start, len, timeout, _IOERR_LOCK)
 70}
 71
 72func osLock(file *os.File, typ int16, start, len int64, timeout time.Duration, def _ErrorCode) _ErrorCode {
 73	lock := &flocktimeout_t{fl: unix.Flock_t{
 74		Type:  typ,
 75		Start: start,
 76		Len:   len,
 77	}}
 78	var err error
 79	switch {
 80	case timeout == 0:
 81		err = unix.FcntlFlock(file.Fd(), _F_OFD_SETLK, &lock.fl)
 82	case timeout < 0:
 83		err = unix.FcntlFlock(file.Fd(), _F_OFD_SETLKW, &lock.fl)
 84	default:
 85		lock.timeout = unix.NsecToTimespec(int64(timeout / time.Nanosecond))
 86		err = unix.FcntlFlock(file.Fd(), _F_OFD_SETLKWTIMEOUT, &lock.fl)
 87		runtime.KeepAlive(lock)
 88	}
 89	return osLockErrorCode(err, def)
 90}
 91
 92func osUnlock(file *os.File, start, len int64) _ErrorCode {
 93	lock := unix.Flock_t{
 94		Type:  unix.F_UNLCK,
 95		Start: start,
 96		Len:   len,
 97	}
 98	for {
 99		err := unix.FcntlFlock(file.Fd(), _F_OFD_SETLK, &lock)
100		if err == nil {
101			return _OK
102		}
103		if err != unix.EINTR {
104			return _IOERR_UNLOCK
105		}
106	}
107}