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sleep.c revision 1.15.2.2 
      1 /*	$NetBSD: sleep.c,v 1.15.2.2 1996/09/20 17:00:18 jtc Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)sleep.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 static char rcsid[] = "$NetBSD: sleep.c,v 1.15.2.2 1996/09/20 17:00:18 jtc Exp $";
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include "namespace.h"
     45 #include <sys/time.h>
     46 #include <signal.h>
     47 #include <unistd.h>
     48 
     49 #ifdef __weak_alias
     50 __weak_alias(sleep,_sleep);
     51 #endif
     52 
     53 static volatile int ringring;
     54 
     55 unsigned int
     56 sleep(seconds)
     57 	unsigned int seconds;
     58 {
     59 	struct itimerval itv, oitv;
     60 	struct sigaction act, oact;
     61 	struct timeval diff;
     62 	sigset_t set, oset;
     63 	static void sleephandler();
     64 
     65 	if (!seconds)
     66 		return 0;
     67 
     68 	sigemptyset(&set);
     69 	sigaddset(&set, SIGALRM);
     70 	sigprocmask(SIG_BLOCK, &set, &oset);
     71 
     72 	act.sa_handler = sleephandler;
     73 	act.sa_flags = 0;
     74 	sigemptyset(&act.sa_mask);
     75 	sigaction(SIGALRM, &act, &oact);
     76 
     77 	timerclear(&itv.it_interval);
     78 	itv.it_value.tv_sec = seconds;
     79 	itv.it_value.tv_usec = 0;
     80 	timerclear(&diff);
     81 	setitimer(ITIMER_REAL, &itv, &oitv);
     82 
     83 	if (timerisset(&oitv.it_value)) {
     84 		if (timercmp(&oitv.it_value, &itv.it_value, >)) {
     85 			timersub(&oitv.it_value, &itv.it_value, &oitv.it_value);
     86 		} else {
     87 			/*
     88 			 * The existing timer was scheduled to fire
     89 			 * before ours, so we compute the time diff
     90 			 * so we can add it back in the end.
     91 			 */
     92 			timersub(&itv.it_value, &oitv.it_value, &diff);
     93 			itv.it_value = oitv.it_value;
     94 			/*
     95 			 * This is a hack, but we must have time to return
     96 			 * from the setitimer after the alarm or else it'll
     97 			 * be restarted.  And, anyway, sleep never did
     98 			 * anything more than this before.
     99 			 */
    100 			oitv.it_value.tv_sec  = 1;
    101 			oitv.it_value.tv_usec = 0;
    102 
    103 			setitimer(ITIMER_REAL, &itv, NULL);
    104 		}
    105 	}
    106 
    107 	set = oset;
    108 	sigdelset(&set, SIGALRM);
    109 	ringring = 0;
    110  	(void) sigsuspend(&set);
    111 
    112 	if (!ringring) {
    113 		struct itimerval nulltv;
    114 		/*
    115 		 * Interrupted by other signal; allow for pending
    116 		 * SIGALRM to be processed before resetting handler,
    117 		 * after first turning off the timer.
    118 		 */
    119 		timerclear(&nulltv.it_interval);
    120 		timerclear(&nulltv.it_value);
    121 		(void) setitimer(ITIMER_REAL, &nulltv, &itv);
    122 	} else
    123 		timerclear(&itv.it_value);
    124 	sigprocmask(SIG_SETMASK, &oset, NULL);
    125 	sigaction(SIGALRM, &oact, NULL);
    126 	(void) setitimer(ITIMER_REAL, &oitv, NULL);
    127 
    128 	if (timerisset(&diff))
    129 		timeradd(&itv.it_value, &diff, &itv.it_value);
    130 
    131 	return (itv.it_value.tv_sec);
    132 }
    133 
    134 static void
    135 sleephandler()
    136 {
    137 	ringring = 1;
    138 }
    139