xref: /csrg-svn/lib/libc/gen/sleep.c (revision 26593)
121360Sdist /*
221360Sdist  * Copyright (c) 1980 Regents of the University of California.
321360Sdist  * All rights reserved.  The Berkeley software License Agreement
421360Sdist  * specifies the terms and conditions for redistribution.
521360Sdist  */
621360Sdist 
7*26593Sdonn #if defined(LIBC_SCCS) && !defined(lint)
8*26593Sdonn static char sccsid[] = "@(#)sleep.c	5.2 (Berkeley) 03/09/86";
9*26593Sdonn #endif LIBC_SCCS and not lint
1012977Ssam 
1113582Ssam #include <sys/time.h>
121979Swnj #include <signal.h>
131979Swnj 
1412977Ssam #define	setvec(vec, a) \
1512977Ssam 	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
1612977Ssam 
1714618Skarels static int ringring;
1814618Skarels 
191979Swnj sleep(n)
2012977Ssam 	unsigned n;
211979Swnj {
2212977Ssam 	int sleepx(), omask;
2312977Ssam 	struct itimerval itv, oitv;
2412977Ssam 	register struct itimerval *itp = &itv;
2512977Ssam 	struct sigvec vec, ovec;
261979Swnj 
2712977Ssam 	if (n == 0)
281979Swnj 		return;
2912977Ssam 	timerclear(&itp->it_interval);
3012977Ssam 	timerclear(&itp->it_value);
3112977Ssam 	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
3212977Ssam 		return;
3312977Ssam 	itp->it_value.tv_sec = n;
3412977Ssam 	if (timerisset(&oitv.it_value)) {
3512977Ssam 		if (timercmp(&oitv.it_value, &itp->it_value, >))
3612977Ssam 			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
371979Swnj 		else {
3812977Ssam 			itp->it_value = oitv.it_value;
3912977Ssam 			/*
4013019Ssam 			 * This is a hack, but we must have time to
4114618Skarels 			 * return from the setitimer after the alarm
4213019Ssam 			 * or else it'll be restarted.  And, anyway,
4313019Ssam 			 * sleep never did anything more than this before.
4412977Ssam 			 */
4513019Ssam 			oitv.it_value.tv_sec = 1;
4613019Ssam 			oitv.it_value.tv_usec = 0;
471979Swnj 		}
481979Swnj 	}
4912977Ssam 	setvec(vec, sleepx);
5012977Ssam 	(void) sigvec(SIGALRM, &vec, &ovec);
5117491Skarels 	omask = sigblock(sigmask(SIGALRM));
5214954Skarels 	ringring = 0;
5314618Skarels 	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
5414618Skarels 	while (!ringring)
5517491Skarels 		sigpause(omask &~ sigmask(SIGALRM));
5614618Skarels 	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
5717491Skarels 	(void) sigsetmask(omask);
5814618Skarels 	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
591979Swnj }
601979Swnj 
611979Swnj static
621979Swnj sleepx()
631979Swnj {
6412977Ssam 
6514618Skarels 	ringring = 1;
661979Swnj }
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