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 */
32
33 /*
34 * Test the SVID-compatible Semaphore facility.
35 */
36
37 #include <sys/types.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 /*
67 * This is the original semun union used by the sysvsem utility.
68 * It is deliberately kept here under #if 0'ed condition for future
69 * reference. PLEASE DO NOT REMOVE. The {SET,GET}ALL in FreeBSD
70 * are signed values, so the default version in sys/sem.h suffices.
71 */
72 #if 0
73 union semun {
74 int val; /* value for SETVAL */
75 struct semid_ds *buf; /* buffer for IPC_{STAT,SET} */
76 u_short *array; /* array for GETALL & SETALL */
77 };
78 #endif
79
80 int
main(int argc,char * argv[])81 main(int argc, char *argv[])
82 {
83 struct sigaction sa;
84 union semun sun;
85 struct semid_ds s_ds;
86 sigset_t sigmask;
87 int i;
88
89 if (argc != 2)
90 usage();
91
92 /*
93 * Install a SIGSYS handler so that we can exit gracefully if
94 * System V Semaphore support isn't in the kernel.
95 */
96 sa.sa_handler = sigsys_handler;
97 sigemptyset(&sa.sa_mask);
98 sa.sa_flags = 0;
99 if (sigaction(SIGSYS, &sa, NULL) == -1)
100 err(1, "sigaction SIGSYS");
101
102 /*
103 * Install and SIGCHLD handler to deal with all possible exit
104 * conditions of the receiver.
105 */
106 sa.sa_handler = sigchld_handler;
107 sigemptyset(&sa.sa_mask);
108 sa.sa_flags = 0;
109 if (sigaction(SIGCHLD, &sa, NULL) == -1)
110 err(1, "sigaction SIGCHLD");
111
112 semkey = ftok(argv[1], 4160);
113
114 /*
115 * Initialize child_pid to ourselves to that the cleanup function
116 * works before we create the receiver.
117 */
118 child_pid = getpid();
119
120 /*
121 * Make sure that when the sender exits, the message queue is
122 * removed.
123 */
124 if (atexit(cleanup) == -1)
125 err(1, "atexit");
126
127 if ((sender_semid = semget(semkey, 1, IPC_CREAT | 0640)) == -1)
128 err(1, "semget");
129
130
131 sun.buf = &s_ds;
132 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
133 err(1, "semctl IPC_STAT");
134
135 print_semid_ds(&s_ds, 0640);
136
137 s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;
138
139 sun.buf = &s_ds;
140 if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
141 err(1, "semctl IPC_SET");
142
143 memset(&s_ds, 0, sizeof(s_ds));
144
145 sun.buf = &s_ds;
146 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
147 err(1, "semctl IPC_STAT");
148
149 if ((s_ds.sem_perm.mode & 0777) != 0600)
150 err(1, "IPC_SET of mode didn't hold");
151
152 print_semid_ds(&s_ds, 0600);
153
154 errno = 0;
155 if (semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
156 errno != EEXIST)
157 err(1, "semget IPC_EXCL 1 did not fail with [EEXIST]");
158 errno = 0;
159 if (semget(semkey, 2, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
160 errno != EEXIST)
161 err(1, "semget IPC_EXCL 2 did not fail with [EEXIST]");
162
163 for (child_count = 0; child_count < 5; child_count++) {
164 switch ((child_pid = fork())) {
165 case -1:
166 err(1, "fork");
167 /* NOTREACHED */
168
169 case 0:
170 waiter();
171 break;
172
173 default:
174 break;
175 }
176 }
177
178 /*
179 * Wait for all of the waiters to be attempting to acquire the
180 * semaphore.
181 */
182 for (;;) {
183 i = semctl(sender_semid, 0, GETNCNT);
184 if (i == -1)
185 err(1, "semctl GETNCNT");
186 if (i == 5)
187 break;
188 }
189
190 /*
191 * Now set the thundering herd in motion by initializing the
192 * semaphore to the value 1.
193 */
194 sun.val = 1;
195 if (semctl(sender_semid, 0, SETVAL, sun) == -1)
196 err(1, "sender: semctl SETVAL to 1");
197
198 /*
199 * Suspend forever; when we get SIGCHLD, the handler will exit.
200 */
201 sigemptyset(&sigmask);
202 for (;;) {
203 (void) sigsuspend(&sigmask);
204 if (signal_was_sigchld)
205 signal_was_sigchld = 0;
206 else
207 break;
208 }
209
210 /*
211 * ...and any other signal is an unexpected error.
212 */
213 errx(1, "sender: received unexpected signal");
214 }
215
216 void
sigsys_handler(int signo)217 sigsys_handler(int signo)
218 {
219
220 errx(1, "System V Semaphore support is not present in the kernel");
221 }
222
223 void
sigchld_handler(int signo)224 sigchld_handler(int signo)
225 {
226 union semun sun;
227 struct semid_ds s_ds;
228 int cstatus;
229
230 /*
231 * Reap the child; if it exited successfully, then we're on the
232 * right track!
233 */
234 if (wait(&cstatus) == -1)
235 err(1, "wait");
236
237 if (WIFEXITED(cstatus) == 0)
238 errx(1, "receiver exited abnormally");
239
240 if (WEXITSTATUS(cstatus) != 0)
241 errx(1, "receiver exited with status %d",
242 WEXITSTATUS(cstatus));
243
244 /*
245 * If we get here, the child has exited normally, and we should
246 * decrement the child count. If the child_count reaches 0, we
247 * should exit.
248 */
249
250 sun.buf = &s_ds;
251 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
252 err(1, "semctl IPC_STAT");
253
254 print_semid_ds(&s_ds, 0600);
255
256 if (--child_count != 0) {
257 signal_was_sigchld = 1;
258 return;
259 }
260
261 exit(0);
262 }
263
264 void
cleanup()265 cleanup()
266 {
267
268 /*
269 * If we're the sender, and it exists, remove the message queue.
270 */
271 if (child_pid != 0 && sender_semid != -1) {
272 if (semctl(sender_semid, 0, IPC_RMID) == -1)
273 warn("semctl IPC_RMID");
274 }
275 }
276
277 void
print_semid_ds(struct semid_ds * sp,mode_t mode)278 print_semid_ds(struct semid_ds *sp, mode_t mode)
279 {
280 uid_t uid = geteuid();
281 gid_t gid = getegid();
282
283 printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
284 sp->sem_perm.uid, sp->sem_perm.gid,
285 sp->sem_perm.cuid, sp->sem_perm.cgid,
286 sp->sem_perm.mode & 0777);
287
288 printf("nsems %u\n", sp->sem_nsems);
289
290 printf("otime: %s", ctime(&sp->sem_otime));
291 printf("ctime: %s", ctime(&sp->sem_ctime));
292
293 /*
294 * Sanity check a few things.
295 */
296
297 if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
298 errx(1, "uid mismatch");
299
300 if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
301 errx(1, "gid mismatch");
302
303 if ((sp->sem_perm.mode & 0777) != mode)
304 errx(1, "mode mismatch %o != %o",
305 (sp->sem_perm.mode & 0777), mode);
306 }
307
308 void
usage()309 usage()
310 {
311
312 fprintf(stderr, "usage: %s keypath\n", getprogname());
313 exit(1);
314 }
315
316 void
waiter()317 waiter()
318 {
319 struct sembuf s;
320 int semid;
321
322 if ((semid = semget(semkey, 1, 0)) == -1)
323 err(1, "waiter: semget");
324
325 /*
326 * Attempt to acquire the semaphore.
327 */
328 s.sem_num = 0;
329 s.sem_op = -1;
330 s.sem_flg = SEM_UNDO;
331
332 if (semop(semid, &s, 1) == -1)
333 err(1, "waiter: semop -1");
334
335 printf("WOO! GOT THE SEMAPHORE!\n");
336 sleep(1);
337
338 /*
339 * Release the semaphore and exit.
340 */
341 s.sem_num = 0;
342 s.sem_op = 1;
343 s.sem_flg = SEM_UNDO;
344
345 if (semop(semid, &s, 1) == -1)
346 err(1, "waiter: semop +1");
347
348 exit(0);
349 }
350