usleep.c revision 28173
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#ifndef _THREAD_SAFE 47static int alarm_termination; 48 49static void 50sleephandler() 51{ 52 alarm_termination++; 53} 54#endif /* _THREAD_SAFE */ 55 56 57void 58usleep(useconds) 59 unsigned int useconds; 60{ 61#ifdef _THREAD_SAFE 62 struct timespec time_to_sleep; 63 struct timespec time_remaining; 64 65 if (useconds) { 66 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 67 time_to_sleep.tv_sec = useconds / 1000000; 68 do { 69 (void)nanosleep(&time_to_sleep, &time_remaining); 70 time_to_sleep = time_remaining; 71 } while (time_to_sleep.tv_sec != 0 || 72 time_to_sleep.tv_nsec != 0); 73 } 74#else 75 struct timespec time_to_sleep; 76 struct timespec time_remaining; 77 struct sigaction act, oact; 78 sigset_t mask, omask; 79 int alarm_blocked; 80 81 if (useconds != 0) { 82 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 83 time_to_sleep.tv_sec = useconds / 1000000; 84 85 /* Block SIGALRM while fiddling with it */ 86 sigemptyset(&mask); 87 sigaddset(&mask, SIGALRM); 88 if (sigprocmask(SIG_BLOCK, &mask, &omask)) 89 return; 90 91 alarm_termination = 0; 92 93 /* Was SIGALRM blocked already? */ 94 alarm_blocked = sigismember(&omask, SIGALRM); 95 96 if (!alarm_blocked) { 97 /* 98 * Set up handler to interrupt signanosleep only if 99 * SIGALRM was unblocked. (Save some syscalls) 100 */ 101 memset(&act, 0, sizeof(act)); 102 act.sa_handler = sleephandler; 103 if (sigaction(SIGALRM, &act, &oact)) { 104 (void)sigprocmask(SIG_SETMASK, &omask, 105 (sigset_t *)0); 106 return; 107 } 108 } 109 110 /* 111 * signanosleep() uses the given mask for the lifetime of 112 * the syscall only - it resets on return. Note that the 113 * old sleep() explicitly unblocks SIGALRM during the sleep, 114 * we don't do that now since we don't depend on SIGALRM 115 * to end the timeout. If the process blocks SIGALRM, it 116 * gets what it asks for. 117 */ 118 do { 119 (void)signanosleep(&time_to_sleep, &time_remaining, 120 &omask); 121 time_to_sleep = time_remaining; 122 } while (!alarm_termination && 123 (time_to_sleep.tv_sec != 0 || 124 time_to_sleep.tv_nsec != 0)); 125 126 if (!alarm_blocked) { 127 /* Unwind */ 128 (void)sigaction(SIGALRM, &oact, (struct sigaction *)0); 129 (void)sigprocmask(SIG_SETMASK, &omask, (sigset_t *)0); 130 } 131 } 132#endif /* _THREAD_SAFE */ 133} 134