err = socketpair(domain, typ, proto, &fdx)
	if err == nil {
		fd[0] = int(fdx[0])
		fd[1] = int(fdx[1])
	}
	return
}

var ioSync int64

func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }

func SetNonblock(fd int, nonblocking bool) (err error) {
	flag, err := fcntl(fd, F_GETFL, 0)
	if err != nil {
		return err
	}
	if (flag&O_NONBLOCK != 0) == nonblocking {
		return nil
	}

	EXTB                          = 0xf
	EXTRAP                        = 0x1
	EYEC_RTENTRYA                 = 0x257274656e747241
	EYEC_RTENTRYF                 = 0x257274656e747246
	E_ACC                         = 0x0
	FD_CLOEXEC                    = 0x1
	FD_SETSIZE                    = 0xfffe
	FLUSHBAND                     = 0x40
	FLUSHLOW                      = 0x8
	FLUSHO                        = 0x100000
	FLUSHR                        = 0x1

	EPOLLWRBAND              = 0x0008
	EPOLLPRI                 = 0x0010
	EPOLLERR                 = 0x0020
	EPOLLHUP                 = 0x0040
	EPOLLEXCLUSIVE           = 0x20000000
	EPOLLONESHOT             = 0x40000000
	FD_CLOEXEC               = 0x01
	FD_CLOFORK               = 0x02
	FD_SETSIZE               = 0x800
	FNDELAY                  = 0x04
	F_CLOSFD                 = 9
	F_CONTROL_CVT            = 13
	F_DUPFD                  = 0