1 /* $NetBSD: usleep.c,v 1.10 1995/10/26 22:07:02 pk 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[] = "@(#)usleep.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 static char rcsid[] = "$NetBSD: usleep.c,v 1.10 1995/10/26 22:07:02 pk Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/time.h> 45 #include <signal.h> 46 #include <unistd.h> 47 48 #define TICK 10000 /* system clock resolution in microseconds */ 49 50 static volatile int ringring; 51 52 void 53 usleep(useconds) 54 unsigned int useconds; 55 { 56 struct itimerval itv, oitv; 57 struct sigaction act, oact; 58 sigset_t set, oset; 59 static void sleephandler(); 60 61 if (!useconds) 62 return; 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 = useconds / 1000000; 75 itv.it_value.tv_usec = useconds % 1000000; 76 setitimer(ITIMER_REAL, &itv, &oitv); 77 78 if (timerisset(&oitv.it_value)) { 79 if (timercmp(&oitv.it_value, &itv.it_value, >)) { 80 timersub(&oitv.it_value, &itv.it_value, &oitv.it_value); 81 } else { 82 itv.it_value = oitv.it_value; 83 /* 84 * This is a hack, but we must have time to return 85 * from the setitimer after the alarm or else it'll 86 * be restarted. And, anyway, sleep never did 87 * anything more than this before. 88 */ 89 oitv.it_value.tv_sec = 0; 90 oitv.it_value.tv_usec = 2 * TICK; 91 92 setitimer(ITIMER_REAL, &itv, NULL); 93 } 94 } 95 96 set = oset; 97 sigdelset(&set, SIGALRM); 98 ringring = 0; 99 (void) sigsuspend(&set); 100 101 if (!ringring) { 102 struct itimerval nulltv; 103 /* 104 * Interrupted by other signal; allow for pending 105 * SIGALRM to be processed before resetting handler, 106 * after first turning off the timer. 107 */ 108 timerclear(&nulltv.it_interval); 109 timerclear(&nulltv.it_value); 110 (void) setitimer(ITIMER_REAL, &nulltv, NULL); 111 } 112 sigprocmask(SIG_SETMASK, &oset, NULL); 113 sigaction(SIGALRM, &oact, NULL); 114 (void) setitimer(ITIMER_REAL, &oitv, NULL); 115 } 116 117 static void 118 sleephandler() 119 { 120 ringring = 1; 121 } 122