1 /* $NetBSD: usleep.c,v 1.6 1995/03/21 13:50:32 mycroft 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 1.6 1995/03/21 13:50:32 mycroft 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 void 51 usleep(useconds) 52 unsigned int useconds; 53 { 54 struct itimerval itv, oitv; 55 struct sigaction act, oact; 56 sigset_t set, oset; 57 static void sleephandler(); 58 59 if (!useconds) 60 return; 61 62 sigemptyset(&set); 63 sigaddset(&set, SIGALRM); 64 sigprocmask(SIG_BLOCK, &set, &oset); 65 66 act.sa_handler = sleephandler; 67 act.sa_flags = 0; 68 sigemptyset(&act.sa_mask); 69 sigaction(SIGALRM, &act, &oact); 70 71 timerclear(&itv.it_interval); 72 itv.it_value.tv_sec = useconds / 1000000; 73 itv.it_value.tv_usec = useconds % 1000000; 74 setitimer(ITIMER_REAL, &itv, &oitv); 75 76 if (timerisset(&oitv.it_value)) { 77 if (timercmp(&oitv.it_value, &itv.it_value, >)) { 78 timersub(&oitv.it_value, &itv.it_value, &oitv.it_value); 79 } else { 80 itv.it_value = oitv.it_value; 81 /* 82 * This is a hack, but we must have time to return 83 * from the setitimer after the alarm or else it'll 84 * be restarted. And, anyway, sleep never did 85 * anything more than this before. 86 */ 87 oitv.it_value.tv_sec = 0; 88 oitv.it_value.tv_usec = 2 * TICK; 89 90 setitimer(ITIMER_REAL, &itv, NULL); 91 } 92 } 93 94 (void) sigsuspend(&oset); 95 96 sigaction(SIGALRM, &oact, NULL); 97 sigprocmask(SIG_SETMASK, &oset, NULL); 98 99 (void) setitimer(ITIMER_REAL, &oitv, &itv); 100 } 101 102 static void 103 sleephandler() 104 { 105 106 } 107