regress/sys/kern/sysvsem/semtest.c

   1 /*      $NetBSD: semtest.c,v 1.5 2005/02/06 06:05:20 perry Exp $        */
   2
   3 /*-
   4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
   9  * NASA Ames Research Center.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  * POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * Test the SVID-compatible Semaphore facility.
  35  */
  36
  37 #include <sys/param.h>
  38 #include <sys/ipc.h>
  39 #include <sys/sem.h>
  40 #include <sys/wait.h>
  41
  42 #include <err.h>
  43 #include <errno.h>
  44 #include <signal.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <time.h>
  49 #include <unistd.h>
  50
  51 int     main(int, char *[]);
  52 void    print_semid_ds(struct semid_ds *, mode_t);
  53 void    sigsys_handler(int);
  54 void    sigchld_handler(int);
  55 void    cleanup(void);
  56 void    waiter(void);
  57 void    usage(void);
  58
  59 int     sender_semid = -1;
  60 pid_t   child_pid;
  61 int     child_count;
  62 int     signal_was_sigchld;
  63
  64 key_t   semkey;
  65
  66 union semun {
  67         int     val;            /* value for SETVAL */
  68         struct  semid_ds *buf;  /* buffer for IPC_{STAT,SET} */
  69         u_short *array;         /* array for GETALL & SETALL */
  70 };
  71
  72 int
  73 main(argc, argv)
  74         int argc;
  75         char *argv[];
  76 {
  77         struct sigaction sa;
  78         union semun sun;
  79         struct semid_ds s_ds;
  80         sigset_t sigmask;
  81         int i;
  82
  83         if (argc != 2)
  84                 usage();
  85
  86         /*
  87          * Install a SIGSYS handler so that we can exit gracefully if
  88          * System V Semaphore support isn't in the kernel.
  89          */
  90         sa.sa_handler = sigsys_handler;
  91         sigemptyset(&sa.sa_mask);
  92         sa.sa_flags = 0;
  93         if (sigaction(SIGSYS, &sa, NULL) == -1)
  94                 err(1, "sigaction SIGSYS");
  95
  96         /*
  97          * Install and SIGCHLD handler to deal with all possible exit
  98          * conditions of the receiver.
  99          */
 100         sa.sa_handler = sigchld_handler;
 101         sigemptyset(&sa.sa_mask);
 102         sa.sa_flags = 0;
 103         if (sigaction(SIGCHLD, &sa, NULL) == -1)
 104                 err(1, "sigaction SIGCHLD");
 105
 106         semkey = ftok(argv[1], 4160);
 107
 108         /*
 109          * Initialize child_pid to ourselves to that the cleanup function
 110          * works before we create the receiver.
 111          */
 112         child_pid = getpid();
 113
 114         /*
 115          * Make sure that when the sender exits, the message queue is
 116          * removed.
 117          */
 118         if (atexit(cleanup) == -1)
 119                 err(1, "atexit");
 120
 121         if ((sender_semid = semget(semkey, 1, IPC_CREAT | 0640)) == -1)
 122                 err(1, "semget");
 123
 124
 125         sun.buf = &s_ds;
 126         if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
 127                 err(1, "semctl IPC_STAT");
 128
 129         print_semid_ds(&s_ds, 0640);
 130
 131         s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;
 132
 133         sun.buf = &s_ds;
 134         if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
 135                 err(1, "semctl IPC_SET");
 136
 137         memset(&s_ds, 0, sizeof(s_ds));
 138
 139         sun.buf = &s_ds;
 140         if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
 141                 err(1, "semctl IPC_STAT");
 142
 143         if ((s_ds.sem_perm.mode & 0777) != 0600)
 144                 err(1, "IPC_SET of mode didn't hold");
 145
 146         print_semid_ds(&s_ds, 0600);
 147
 148         for (child_count = 0; child_count < 5; child_count++) {
 149                 switch ((child_pid = fork())) {
 150                 case -1:
 151                         err(1, "fork");
 152                         /* NOTREACHED */
 153
 154                 case 0:
 155                         waiter();
 156                         break;
 157
 158                 default:
 159                         break;
 160                 }
 161         }
 162
 163         /*
 164          * Wait for all of the waiters to be attempting to acquire the
 165          * semaphore.
 166          */
 167         for (;;) {
 168                 i = semctl(sender_semid, 0, GETNCNT);
 169                 if (i == -1)
 170                         err(1, "semctl GETNCNT");
 171                 if (i == 5)
 172                         break;
 173         }
 174
 175         /*
 176          * Now set the thundering herd in motion by initializing the
 177          * semaphore to the value 1.
 178          */
 179         sun.val = 1;
 180         if (semctl(sender_semid, 0, SETVAL, sun) == -1)
 181                 err(1, "sender: semctl SETVAL to 1");
 182
 183         /*
 184          * Suspend forever; when we get SIGCHLD, the handler will exit.
 185          */
 186         sigemptyset(&sigmask);
 187         for (;;) {
 188                 (void) sigsuspend(&sigmask);
 189                 if (signal_was_sigchld)
 190                         signal_was_sigchld = 0;
 191                 else
 192                         break;
 193         }
 194
 195         /*
 196          * ...and any other signal is an unexpected error.
 197          */
 198         errx(1, "sender: received unexpected signal");
 199 }
 200
 201 void
 202 sigsys_handler(signo)
 203         int signo;
 204 {
 205
 206         errx(1, "System V Semaphore support is not present in the kernel");
 207 }
 208
 209 void
 210 sigchld_handler(signo)
 211         int signo;
 212 {
 213         union semun sun;
 214         struct semid_ds s_ds;
 215         int cstatus;
 216
 217         /*
 218          * Reap the child; if it exited successfully, then we're on the
 219          * right track!
 220          */
 221         if (wait(&cstatus) == -1)
 222                 err(1, "wait");
 223
 224         if (WIFEXITED(cstatus) == 0)
 225                 errx(1, "receiver exited abnormally");
 226
 227         if (WEXITSTATUS(cstatus) != 0)
 228                 errx(1, "receiver exited with status %d",
 229                     WEXITSTATUS(cstatus));
 230
 231         /*
 232          * If we get here, the child has exited normally, and we should
 233          * decrement the child count.  If the child_count reaches 0, we
 234          * should exit.
 235          */
 236
 237         sun.buf = &s_ds;
 238         if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
 239                 err(1, "semctl IPC_STAT");
 240
 241         print_semid_ds(&s_ds, 0600);
 242
 243         if (--child_count != 0) {
 244                 signal_was_sigchld = 1;
 245                 return;
 246         }
 247
 248         exit(0);
 249 }
 250
 251 void
 252 cleanup()
 253 {
 254
 255         /*
 256          * If we're the sender, and it exists, remove the message queue.
 257          */
 258         if (child_pid != 0 && sender_semid != -1) {
 259                 if (semctl(sender_semid, 0, IPC_RMID) == -1)
 260                         warn("semctl IPC_RMID");
 261         }
 262 }
 263
 264 void
 265 print_semid_ds(sp, mode)
 266         struct semid_ds *sp;
 267         mode_t mode;
 268 {
 269         uid_t uid = geteuid();
 270         gid_t gid = getegid();
 271
 272         printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
 273             sp->sem_perm.uid, sp->sem_perm.gid,
 274             sp->sem_perm.cuid, sp->sem_perm.cgid,
 275             sp->sem_perm.mode & 0777);
 276
 277         printf("nsems %u\n", sp->sem_nsems);
 278
 279         printf("otime: %s", ctime(&sp->sem_otime));
 280         printf("ctime: %s", ctime(&sp->sem_ctime));
 281
 282         /*
 283          * Sanity check a few things.
 284          */
 285
 286         if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
 287                 errx(1, "uid mismatch");
 288
 289         if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
 290                 errx(1, "gid mismatch");
 291
 292         if ((sp->sem_perm.mode & 0777) != mode)
 293                 errx(1, "mode mismatch %o != %o",
 294                     (sp->sem_perm.mode & 0777), mode);
 295 }
 296
 297 void
 298 usage()
 299 {
 300
 301         fprintf(stderr, "usage: %s keypath\n", getprogname());
 302         exit(1);
 303 }
 304
 305 void
 306 waiter()
 307 {
 308         struct sembuf s;
 309         int semid;
 310
 311         if ((semid = semget(semkey, 1, 0)) == -1)
 312                 err(1, "waiter: semget");
 313
 314         /*
 315          * Attempt to acquire the semaphore.
 316          */
 317         s.sem_num = 0;
 318         s.sem_op = -1;
 319         s.sem_flg = SEM_UNDO;
 320
 321         if (semop(semid, &s, 1) == -1)
 322                 err(1, "waiter: semop -1");
 323
 324         printf("WOO!  GOT THE SEMAPHORE!\n");
 325         sleep(1);
 326
 327         /*
 328          * Release the semaphore and exit.
 329          */
 330         s.sem_num = 0;
 331         s.sem_op = 1;
 332         s.sem_flg = SEM_UNDO;
 333
 334         if (semop(semid, &s, 1) == -1)
 335                 err(1, "waiter: semop +1");
 336
 337         exit(0);
 338 }