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Annotation of src/lib/libc/gen/usleep.c, Revision 1.11

1.11    ! christos    1: /*     $NetBSD: usleep.c,v 1.10 1995/10/26 22:07:02 pk Exp $   */
1.4       cgd         2:
1.1       cgd         3: /*
1.4       cgd         4:  * Copyright (c) 1989, 1993
                      5:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         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:
1.11    ! christos   36: #include <sys/cdefs.h>
1.1       cgd        37: #if defined(LIBC_SCCS) && !defined(lint)
1.4       cgd        38: #if 0
                     39: static char sccsid[] = "@(#)usleep.c   8.1 (Berkeley) 6/4/93";
                     40: #else
1.11    ! christos   41: __RCSID("$NetBSD$");
1.4       cgd        42: #endif
1.1       cgd        43: #endif /* LIBC_SCCS and not lint */
                     44:
                     45: #include <sys/time.h>
1.5       jtc        46: #include <signal.h>
1.1       cgd        47: #include <unistd.h>
                     48:
                     49: #define        TICK    10000           /* system clock resolution in microseconds */
                     50:
1.9       pk         51: static volatile int ringring;
1.11    ! christos   52: static void sleephandler __P((int));
1.9       pk         53:
1.1       cgd        54: void
                     55: usleep(useconds)
                     56:        unsigned int useconds;
                     57: {
                     58:        struct itimerval itv, oitv;
1.6       mycroft    59:        struct sigaction act, oact;
                     60:        sigset_t set, oset;
1.1       cgd        61:
                     62:        if (!useconds)
                     63:                return;
1.6       mycroft    64:
                     65:        sigemptyset(&set);
                     66:        sigaddset(&set, SIGALRM);
                     67:        sigprocmask(SIG_BLOCK, &set, &oset);
                     68:
                     69:        act.sa_handler = sleephandler;
                     70:        act.sa_flags = 0;
                     71:        sigemptyset(&act.sa_mask);
                     72:        sigaction(SIGALRM, &act, &oact);
                     73:
                     74:        timerclear(&itv.it_interval);
                     75:        itv.it_value.tv_sec = useconds / 1000000;
                     76:        itv.it_value.tv_usec = useconds % 1000000;
                     77:        setitimer(ITIMER_REAL, &itv, &oitv);
                     78:
1.1       cgd        79:        if (timerisset(&oitv.it_value)) {
1.6       mycroft    80:                if (timercmp(&oitv.it_value, &itv.it_value, >)) {
                     81:                        timersub(&oitv.it_value, &itv.it_value, &oitv.it_value);
1.1       cgd        82:                } else {
1.6       mycroft    83:                        itv.it_value = oitv.it_value;
                     84:                        /*
                     85:                         * This is a hack, but we must have time to return
                     86:                         * from the setitimer after the alarm or else it'll
                     87:                         * be restarted.  And, anyway, sleep never did
                     88:                         * anything more than this before.
                     89:                         */
1.1       cgd        90:                        oitv.it_value.tv_sec = 0;
                     91:                        oitv.it_value.tv_usec = 2 * TICK;
1.6       mycroft    92:
                     93:                        setitimer(ITIMER_REAL, &itv, NULL);
1.1       cgd        94:                }
                     95:        }
1.6       mycroft    96:
1.7       mycroft    97:        set = oset;
                     98:        sigdelset(&set, SIGALRM);
1.9       pk         99:        ringring = 0;
1.7       mycroft   100:        (void) sigsuspend(&set);
1.6       mycroft   101:
1.10      pk        102:        if (!ringring) {
                    103:                struct itimerval nulltv;
1.9       pk        104:                /*
                    105:                 * Interrupted by other signal; allow for pending
1.10      pk        106:                 * SIGALRM to be processed before resetting handler,
                    107:                 * after first turning off the timer.
1.9       pk        108:                 */
1.10      pk        109:                timerclear(&nulltv.it_interval);
                    110:                timerclear(&nulltv.it_value);
                    111:                (void) setitimer(ITIMER_REAL, &nulltv, NULL);
1.9       pk        112:        }
1.10      pk        113:        sigprocmask(SIG_SETMASK, &oset, NULL);
                    114:        sigaction(SIGALRM, &oact, NULL);
                    115:        (void) setitimer(ITIMER_REAL, &oitv, NULL);
1.1       cgd       116: }
                    117:
                    118: static void
1.11    ! christos  119: sleephandler(n)
        !           120:        int n;
1.1       cgd       121: {
1.9       pk        122:        ringring = 1;
1.1       cgd       123: }

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