usleep.c revision 26338
1/* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#if defined(LIBC_SCCS) && !defined(lint) 35static char sccsid[] = "@(#)usleep.c 8.1 (Berkeley) 6/4/93"; 36#endif /* LIBC_SCCS and not lint */ 37 38#include <sys/time.h> 39#include <signal.h> 40#include <unistd.h> 41#ifdef _THREAD_SAFE 42#include <pthread.h> 43#include "pthread_private.h" 44#endif 45 46#if !defined(_THREAD_SAFE) && !defined(USE_NANOSLEEP) 47#define TICK 10000 /* system clock resolution in microseconds */ 48#define USPS 1000000 /* number of microseconds in a second */ 49#endif 50 51#ifndef _THREAD_SAFE 52#ifndef USE_NANOSLEEP 53#define setvec(vec, a) \ 54 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 55 56static int ringring; 57#endif 58 59static void 60sleephandler() 61{ 62#ifndef USE_NANOSLEEP 63 ringring = 1; 64#endif 65} 66#endif /* _THREAD_SAFE */ 67 68 69void 70usleep(useconds) 71 unsigned int useconds; 72{ 73#ifdef _THREAD_SAFE 74 struct timespec time_to_sleep; 75 struct timespec time_remaining; 76 77 if (useconds) { 78 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 79 time_to_sleep.tv_sec = useconds / 1000000; 80 do { 81 nanosleep(&time_to_sleep, &time_remaining); 82 time_to_sleep = time_remaining; 83 } while (time_to_sleep.tv_sec != 0 && 84 time_to_sleep.tv_nsec != 0); 85 } 86#else 87#ifdef USE_NANOSLEEP 88 struct timespec time_to_sleep; 89 struct timespec time_remaining; 90 struct sigaction act, oact; 91 sigset_t mask, omask; 92 int alarm_blocked; 93 94 if (useconds != 0) { 95 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 96 time_to_sleep.tv_sec = useconds / 1000000; 97 98 /* Block SIGALRM while fiddling with it */ 99 sigemptyset(&mask); 100 sigaddset(&mask, SIGALRM); 101 sigprocmask(SIG_BLOCK, &mask, &omask); 102 103 /* Was SIGALRM blocked already? */ 104 alarm_blocked = sigismember(&omask, SIGALRM); 105 106 if (!alarm_blocked) { 107 /* 108 * Set up handler to interrupt signanosleep only if 109 * SIGALRM was unblocked. (Save some syscalls) 110 */ 111 memset(&act, 0, sizeof(act)); 112 act.sa_handler = sleephandler; 113 sigaction(SIGALRM, &act, &oact); 114 } 115 116 /* 117 * signanosleep() uses the given mask for the lifetime of 118 * the syscall only - it resets on return. Note that the 119 * Old sleep explicitly unblocks SIGALRM during the sleep, 120 * we don't do that now since we don't depend on SIGALRM 121 * to end the timout. If the process blocks SIGALRM, it 122 * gets what it asks for. 123 */ 124 125 do { 126 signanosleep(&time_to_sleep, &time_remaining, &mask); 127 time_to_sleep = time_remaining; 128 } while (time_to_sleep.tv_sec != 0 && 129 time_to_sleep.tv_nsec != 0); 130 131 if (!alarm_blocked) { 132 /* Unwind */ 133 sigaction(SIGALRM, &oact, (struct sigaction *)0); 134 sigprocmask(SIG_SETMASK, &omask, (sigset_t *)0); 135 } 136 } 137#else 138 register struct itimerval *itp; 139 struct itimerval itv, oitv; 140 struct sigvec vec, ovec; 141 long omask; 142 static void sleephandler(); 143 144 itp = &itv; 145 if (!useconds) 146 return; 147 timerclear(&itp->it_interval); 148 timerclear(&itp->it_value); 149 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 150 return; 151 itp->it_value.tv_sec = useconds / USPS; 152 itp->it_value.tv_usec = useconds % USPS; 153 if (timerisset(&oitv.it_value)) { 154 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 155 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 156 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 157 if (oitv.it_value.tv_usec < 0) { 158 oitv.it_value.tv_usec += USPS; 159 oitv.it_value.tv_sec--; 160 } 161 } else { 162 itp->it_value = oitv.it_value; 163 oitv.it_value.tv_sec = 0; 164 oitv.it_value.tv_usec = 2 * TICK; 165 } 166 } 167 setvec(vec, sleephandler); 168 (void) sigvec(SIGALRM, &vec, &ovec); 169 omask = sigblock(sigmask(SIGALRM)); 170 ringring = 0; 171 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 172 while (!ringring) 173 sigpause(omask &~ sigmask(SIGALRM)); 174 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 175 (void) sigsetmask(omask); 176 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 177#endif /* USE_NANOSLEEP */ 178#endif /* _THREAD_SAFE */ 179} 180