1 /*-
2 * Copyright (c) 1999 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to The NetBSD Foundation
6 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
7 * NASA Ames Research Center.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 *
30 * Obtained from: $NetBSD: semtest.c,v 1.4 2002/07/20 08:36:25 grant Exp $
31 * $FreeBSD$
32 */
33
34 /*
35 * Test the SVID-compatible Semaphore facility.
36 */
37
38 #include <sys/types.h>
39 #include <sys/ipc.h>
40 #include <sys/sem.h>
41 #include <sys/wait.h>
42
43 #include <err.h>
44 #include <errno.h>
45 #include <signal.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <time.h>
50 #include <unistd.h>
51
52 int main (int, char *[]);
53 void print_semid_ds (struct semid_ds *, mode_t);
54 void sigsys_handler (int);
55 void sigchld_handler(int);
56 void cleanup (void);
57 void waiter (void);
58 void usage (void);
59
60 int sender_semid = -1;
61 pid_t child_pid;
62 int child_count;
63 int signal_was_sigchld;
64
65 key_t semkey;
66
67 /*
68 * This is the original semun union used by the sysvsem utility.
69 * It is deliberately kept here under #if 0'ed condition for future
70 * reference. PLEASE DO NOT REMOVE. The {SET,GET}ALL in FreeBSD
71 * are signed values, so the default version in sys/sem.h suffices.
72 */
73 #if 0
74 union semun {
75 int val; /* value for SETVAL */
76 struct semid_ds *buf; /* buffer for IPC_{STAT,SET} */
77 u_short *array; /* array for GETALL & SETALL */
78 };
79 #endif
80
81 int
main(int argc,char * argv[])82 main(int argc, char *argv[])
83 {
84 struct sigaction sa;
85 union semun sun;
86 struct semid_ds s_ds;
87 sigset_t sigmask;
88 int i;
89
90 if (argc != 2)
91 usage();
92
93 /*
94 * Install a SIGSYS handler so that we can exit gracefully if
95 * System V Semaphore support isn't in the kernel.
96 */
97 sa.sa_handler = sigsys_handler;
98 sigemptyset(&sa.sa_mask);
99 sa.sa_flags = 0;
100 if (sigaction(SIGSYS, &sa, NULL) == -1)
101 err(1, "sigaction SIGSYS");
102
103 /*
104 * Install and SIGCHLD handler to deal with all possible exit
105 * conditions of the receiver.
106 */
107 sa.sa_handler = sigchld_handler;
108 sigemptyset(&sa.sa_mask);
109 sa.sa_flags = 0;
110 if (sigaction(SIGCHLD, &sa, NULL) == -1)
111 err(1, "sigaction SIGCHLD");
112
113 semkey = ftok(argv[1], 4160);
114
115 /*
116 * Initialize child_pid to ourselves to that the cleanup function
117 * works before we create the receiver.
118 */
119 child_pid = getpid();
120
121 /*
122 * Make sure that when the sender exits, the message queue is
123 * removed.
124 */
125 if (atexit(cleanup) == -1)
126 err(1, "atexit");
127
128 if ((sender_semid = semget(semkey, 1, IPC_CREAT | 0640)) == -1)
129 err(1, "semget");
130
131
132 sun.buf = &s_ds;
133 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
134 err(1, "semctl IPC_STAT");
135
136 print_semid_ds(&s_ds, 0640);
137
138 s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;
139
140 sun.buf = &s_ds;
141 if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
142 err(1, "semctl IPC_SET");
143
144 memset(&s_ds, 0, sizeof(s_ds));
145
146 sun.buf = &s_ds;
147 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
148 err(1, "semctl IPC_STAT");
149
150 if ((s_ds.sem_perm.mode & 0777) != 0600)
151 err(1, "IPC_SET of mode didn't hold");
152
153 print_semid_ds(&s_ds, 0600);
154
155 errno = 0;
156 if (semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
157 errno != EEXIST)
158 err(1, "semget IPC_EXCL 1 did not fail with [EEXIST]");
159 errno = 0;
160 if (semget(semkey, 2, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
161 errno != EEXIST)
162 err(1, "semget IPC_EXCL 2 did not fail with [EEXIST]");
163
164 for (child_count = 0; child_count < 5; child_count++) {
165 switch ((child_pid = fork())) {
166 case -1:
167 err(1, "fork");
168 /* NOTREACHED */
169
170 case 0:
171 waiter();
172 break;
173
174 default:
175 break;
176 }
177 }
178
179 /*
180 * Wait for all of the waiters to be attempting to acquire the
181 * semaphore.
182 */
183 for (;;) {
184 i = semctl(sender_semid, 0, GETNCNT);
185 if (i == -1)
186 err(1, "semctl GETNCNT");
187 if (i == 5)
188 break;
189 }
190
191 /*
192 * Now set the thundering herd in motion by initializing the
193 * semaphore to the value 1.
194 */
195 sun.val = 1;
196 if (semctl(sender_semid, 0, SETVAL, sun) == -1)
197 err(1, "sender: semctl SETVAL to 1");
198
199 /*
200 * Suspend forever; when we get SIGCHLD, the handler will exit.
201 */
202 sigemptyset(&sigmask);
203 for (;;) {
204 (void) sigsuspend(&sigmask);
205 if (signal_was_sigchld)
206 signal_was_sigchld = 0;
207 else
208 break;
209 }
210
211 /*
212 * ...and any other signal is an unexpected error.
213 */
214 errx(1, "sender: received unexpected signal");
215 }
216
217 void
sigsys_handler(int signo)218 sigsys_handler(int signo)
219 {
220
221 errx(1, "System V Semaphore support is not present in the kernel");
222 }
223
224 void
sigchld_handler(int signo)225 sigchld_handler(int signo)
226 {
227 union semun sun;
228 struct semid_ds s_ds;
229 int cstatus;
230
231 /*
232 * Reap the child; if it exited successfully, then we're on the
233 * right track!
234 */
235 if (wait(&cstatus) == -1)
236 err(1, "wait");
237
238 if (WIFEXITED(cstatus) == 0)
239 errx(1, "receiver exited abnormally");
240
241 if (WEXITSTATUS(cstatus) != 0)
242 errx(1, "receiver exited with status %d",
243 WEXITSTATUS(cstatus));
244
245 /*
246 * If we get here, the child has exited normally, and we should
247 * decrement the child count. If the child_count reaches 0, we
248 * should exit.
249 */
250
251 sun.buf = &s_ds;
252 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
253 err(1, "semctl IPC_STAT");
254
255 print_semid_ds(&s_ds, 0600);
256
257 if (--child_count != 0) {
258 signal_was_sigchld = 1;
259 return;
260 }
261
262 exit(0);
263 }
264
265 void
cleanup()266 cleanup()
267 {
268
269 /*
270 * If we're the sender, and it exists, remove the message queue.
271 */
272 if (child_pid != 0 && sender_semid != -1) {
273 if (semctl(sender_semid, 0, IPC_RMID) == -1)
274 warn("semctl IPC_RMID");
275 }
276 }
277
278 void
print_semid_ds(struct semid_ds * sp,mode_t mode)279 print_semid_ds(struct semid_ds *sp, mode_t mode)
280 {
281 uid_t uid = geteuid();
282 gid_t gid = getegid();
283
284 printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
285 sp->sem_perm.uid, sp->sem_perm.gid,
286 sp->sem_perm.cuid, sp->sem_perm.cgid,
287 sp->sem_perm.mode & 0777);
288
289 printf("nsems %u\n", sp->sem_nsems);
290
291 printf("otime: %s", ctime(&sp->sem_otime));
292 printf("ctime: %s", ctime(&sp->sem_ctime));
293
294 /*
295 * Sanity check a few things.
296 */
297
298 if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
299 errx(1, "uid mismatch");
300
301 if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
302 errx(1, "gid mismatch");
303
304 if ((sp->sem_perm.mode & 0777) != mode)
305 errx(1, "mode mismatch %o != %o",
306 (sp->sem_perm.mode & 0777), mode);
307 }
308
309 void
usage()310 usage()
311 {
312
313 fprintf(stderr, "usage: %s keypath\n", getprogname());
314 exit(1);
315 }
316
317 void
waiter()318 waiter()
319 {
320 struct sembuf s;
321 int semid;
322
323 if ((semid = semget(semkey, 1, 0)) == -1)
324 err(1, "waiter: semget");
325
326 /*
327 * Attempt to acquire the semaphore.
328 */
329 s.sem_num = 0;
330 s.sem_op = -1;
331 s.sem_flg = SEM_UNDO;
332
333 if (semop(semid, &s, 1) == -1)
334 err(1, "waiter: semop -1");
335
336 printf("WOO! GOT THE SEMAPHORE!\n");
337 sleep(1);
338
339 /*
340 * Release the semaphore and exit.
341 */
342 s.sem_num = 0;
343 s.sem_op = 1;
344 s.sem_flg = SEM_UNDO;
345
346 if (semop(semid, &s, 1) == -1)
347 err(1, "waiter: semop +1");
348
349 exit(0);
350 }
351