1 /* $NetBSD: sleep.c,v 1.16 1997/07/13 19:31:25 christos 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 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)sleep.c 8.1 (Berkeley) 6/4/93"; 40 #else 41 __RCSID("$NetBSD: sleep.c,v 1.16 1997/07/13 19:31:25 christos Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/time.h> 46 #include <signal.h> 47 #include <unistd.h> 48 49 static volatile int ringring; 50 static void sleephandler __P((int)); 51 52 unsigned int 53 sleep(seconds) 54 unsigned int seconds; 55 { 56 struct itimerval itv, oitv; 57 struct sigaction act, oact; 58 struct timeval diff; 59 sigset_t set, oset; 60 61 if (!seconds) 62 return 0; 63 64 sigemptyset(&set); 65 sigaddset(&set, SIGALRM); 66 sigprocmask(SIG_BLOCK, &set, &oset); 67 68 act.sa_handler = sleephandler; 69 act.sa_flags = 0; 70 sigemptyset(&act.sa_mask); 71 sigaction(SIGALRM, &act, &oact); 72 73 timerclear(&itv.it_interval); 74 itv.it_value.tv_sec = seconds; 75 itv.it_value.tv_usec = 0; 76 timerclear(&diff); 77 setitimer(ITIMER_REAL, &itv, &oitv); 78 79 if (timerisset(&oitv.it_value)) { 80 if (timercmp(&oitv.it_value, &itv.it_value, >)) { 81 timersub(&oitv.it_value, &itv.it_value, &oitv.it_value); 82 } else { 83 /* 84 * The existing timer was scheduled to fire 85 * before ours, so we compute the time diff 86 * so we can add it back in the end. 87 */ 88 timersub(&itv.it_value, &oitv.it_value, &diff); 89 itv.it_value = oitv.it_value; 90 /* 91 * This is a hack, but we must have time to return 92 * from the setitimer after the alarm or else it'll 93 * be restarted. And, anyway, sleep never did 94 * anything more than this before. 95 */ 96 oitv.it_value.tv_sec = 1; 97 oitv.it_value.tv_usec = 0; 98 99 setitimer(ITIMER_REAL, &itv, NULL); 100 } 101 } 102 103 set = oset; 104 sigdelset(&set, SIGALRM); 105 ringring = 0; 106 (void) sigsuspend(&set); 107 108 if (!ringring) { 109 struct itimerval nulltv; 110 /* 111 * Interrupted by other signal; allow for pending 112 * SIGALRM to be processed before resetting handler, 113 * after first turning off the timer. 114 */ 115 timerclear(&nulltv.it_interval); 116 timerclear(&nulltv.it_value); 117 (void) setitimer(ITIMER_REAL, &nulltv, &itv); 118 } else 119 timerclear(&itv.it_value); 120 sigprocmask(SIG_SETMASK, &oset, NULL); 121 sigaction(SIGALRM, &oact, NULL); 122 (void) setitimer(ITIMER_REAL, &oitv, NULL); 123 124 if (timerisset(&diff)) 125 timeradd(&itv.it_value, &diff, &itv.it_value); 126 127 return (itv.it_value.tv_sec); 128 } 129 130 static void 131 sleephandler(n) 132 int n; 133 { 134 ringring = 1; 135 } 136