pselect.c

让你了解Unix进程间的通信是如何实现的

/*
 * This is *not* a complete implementation of the Posix.1g pselect()
 * function.  For atomicity this must be implemented within the kernel,
 * with the sigprocmask/select/sigprocmask performed as a single atomic
 * operation.
 * This is just a quick hack to allow simple programs using it to compile.
 * Using such programs with this hack will probably lead to race conditions.
 */
/* include pselect */
#include	"unpipc.h"

int
pselect(int nfds, fd_set *rset, fd_set *wset, fd_set *xset,
		const struct timespec *ts, const sigset_t *sigmask)
{
	int				n;
	struct timeval	tv;
	sigset_t		savemask;

	if (ts != NULL) {
		tv.tv_sec = ts->tv_sec;
		tv.tv_usec = ts->tv_nsec / 1000;	/* nanosec -> microsec */
	}

	sigprocmask(SIG_SETMASK, sigmask, &savemask);	/* caller's mask */
	n = select(nfds, rset, wset, xset, (ts == NULL) ? NULL : &tv);
	sigprocmask(SIG_SETMASK, &savemask, NULL);		/* restore mask */

	return(n);
}
/* end pselect */