regress/lib/librt/sem/sem.c

   1 /*      $NetBSD: sem.c,v 1.2 2003/02/28 05:29:48 matt Exp $     */
   2
   3 /*
   4  * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
   5  * 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(s), this list of conditions and the following disclaimer as
  12  *    the first lines of this file unmodified other than the possible
  13  *    addition of one or more copyright notices.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice(s), this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  20  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
  23  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  26  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  27  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  28  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  29  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/wait.h>
  33 #include <assert.h>
  34 #include <stdio.h>
  35 #include <err.h>
  36 #include <fcntl.h>
  37 #include <errno.h>
  38 #include <semaphore.h>
  39 #include <stdlib.h>
  40 #include <unistd.h>
  41
  42 #define NCHILDREN 10
  43
  44 static void
  45 child(sem_t *sem)
  46 {
  47
  48 #ifdef DEBUG
  49         printf("PID %d waiting for semaphore...\n", getpid());
  50 #endif
  51         if (sem_wait(sem))
  52                 err(1, "sem_wait");
  53 #ifdef DEBUG
  54         printf("PID %d got semaphore\n", getpid());
  55 #endif
  56 }
  57
  58 static sem_t *
  59 create_sem(const char *name)
  60 {
  61         sem_t *sem;
  62
  63         (void)sem_unlink(name);
  64         sem = sem_open(name, O_CREAT | O_EXCL, 0644, 0);
  65         assert(sem != SEM_FAILED);
  66
  67         return (sem);
  68 }
  69
  70 static void
  71 delete_sem(sem_t *sem, const char *name)
  72 {
  73
  74         assert(0 == sem_close(sem));
  75         assert(0 == sem_unlink(name));
  76 }
  77
  78 static void
  79 dosem(void)
  80 {
  81         sem_t *sem_a, *sem_b;
  82         pid_t children[NCHILDREN];
  83         unsigned i;
  84         int val, status;
  85         pid_t pid;
  86
  87         assert(-1 != sysconf(_SC_SEMAPHORES));
  88
  89         sem_b = create_sem("/sem_b");
  90         assert(0 == sem_getvalue(sem_b, &val));
  91         assert(0 == val);
  92
  93         assert(0 == sem_post(sem_b));
  94         assert(0 == sem_getvalue(sem_b, &val));
  95         assert(1 == val);
  96
  97         assert(0 == sem_wait(sem_b));
  98         assert(-1 == sem_trywait(sem_b));
  99         assert(EAGAIN == errno);
 100         assert(0 == sem_post(sem_b));
 101         assert(0 == sem_trywait(sem_b));
 102         assert(0 == sem_post(sem_b));
 103         assert(0 == sem_wait(sem_b));
 104         assert(0 == sem_post(sem_b));
 105
 106         delete_sem(sem_b, "/sem_b");
 107
 108         sem_a = create_sem("/sem_a");
 109
 110         for (i = 0; i < NCHILDREN; i++) {
 111                 switch ((pid = fork())) {
 112                 case -1:
 113                         abort();
 114                 case 0:
 115                         child(sem_a);
 116                         _exit(0);
 117                 default:
 118                         children[i] = pid;
 119                         break;
 120                 }
 121         }
 122
 123         for (i = 0; i < NCHILDREN; i++) {
 124                 sleep(1);
 125 #ifdef DEBUG
 126                 printf("main loop 1: posting...\n");
 127 #endif
 128                 assert(0 == sem_post(sem_a));
 129         }
 130
 131         for (i = 0; i < NCHILDREN; i++) {
 132                 assert(children[i] == waitpid(children[i], &status, 0));
 133                 assert(WIFEXITED(status));
 134                 assert(0 == WEXITSTATUS(status));
 135         }
 136
 137         for (i = 0; i < NCHILDREN; i++) {
 138                 switch ((pid = fork())) {
 139                 case -1:
 140                         abort();
 141                 case 0:
 142                         child(sem_a);
 143                         _exit(0);
 144                 default:
 145                         children[i] = pid;
 146                         break;
 147                 }
 148         }
 149
 150         for (i = 0; i < NCHILDREN; i++) {
 151                 sleep(1);
 152 #ifdef DEBUG
 153                 printf("main loop 2: posting...\n");
 154 #endif
 155                 assert(0 == sem_post(sem_a));
 156         }
 157
 158         for (i = 0; i < NCHILDREN; i++) {
 159                 assert(children[i] == waitpid(children[i], &status, 0));
 160                 assert(WIFEXITED(status));
 161                 assert(0 == WEXITSTATUS(status));
 162         }
 163
 164         delete_sem(sem_a, "/sem_a");
 165 }
 166
 167 int
 168 main(int argc, char *argv[])
 169 {
 170 #ifdef DEBUG
 171         printf("Test begin\n");
 172 #endif
 173         dosem();
 174
 175 #ifdef DEBUG
 176         printf("Test end\n");
 177 #endif
 178         return 0;
 179 }