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 for (child_count = 0; child_count < 5; child_count++) {
156 switch ((child_pid = fork())) {
157 case -1:
158 err(1, "fork");
159 /* NOTREACHED */
160
161 case 0:
162 waiter();
163 break;
164
165 default:
166 break;
167 }
168 }
169
170 /*
171 * Wait for all of the waiters to be attempting to acquire the
172 * semaphore.
173 */
174 for (;;) {
175 i = semctl(sender_semid, 0, GETNCNT);
176 if (i == -1)
177 err(1, "semctl GETNCNT");
178 if (i == 5)
179 break;
180 }
181
182 /*
183 * Now set the thundering herd in motion by initializing the
184 * semaphore to the value 1.
185 */
186 sun.val = 1;
187 if (semctl(sender_semid, 0, SETVAL, sun) == -1)
188 err(1, "sender: semctl SETVAL to 1");
189
190 /*
191 * Suspend forever; when we get SIGCHLD, the handler will exit.
192 */
193 sigemptyset(&sigmask);
194 for (;;) {
195 (void) sigsuspend(&sigmask);
196 if (signal_was_sigchld)
197 signal_was_sigchld = 0;
198 else
199 break;
200 }
201
202 /*
203 * ...and any other signal is an unexpected error.
204 */
205 errx(1, "sender: received unexpected signal");
206 }
207
208 void
sigsys_handler(int signo)209 sigsys_handler(int signo)
210 {
211
212 errx(1, "System V Semaphore support is not present in the kernel");
213 }
214
215 void
sigchld_handler(int signo)216 sigchld_handler(int signo)
217 {
218 union semun sun;
219 struct semid_ds s_ds;
220 int cstatus;
221
222 /*
223 * Reap the child; if it exited successfully, then we're on the
224 * right track!
225 */
226 if (wait(&cstatus) == -1)
227 err(1, "wait");
228
229 if (WIFEXITED(cstatus) == 0)
230 errx(1, "receiver exited abnormally");
231
232 if (WEXITSTATUS(cstatus) != 0)
233 errx(1, "receiver exited with status %d",
234 WEXITSTATUS(cstatus));
235
236 /*
237 * If we get here, the child has exited normally, and we should
238 * decrement the child count. If the child_count reaches 0, we
239 * should exit.
240 */
241
242 sun.buf = &s_ds;
243 if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
244 err(1, "semctl IPC_STAT");
245
246 print_semid_ds(&s_ds, 0600);
247
248 if (--child_count != 0) {
249 signal_was_sigchld = 1;
250 return;
251 }
252
253 exit(0);
254 }
255
256 void
cleanup()257 cleanup()
258 {
259
260 /*
261 * If we're the sender, and it exists, remove the message queue.
262 */
263 if (child_pid != 0 && sender_semid != -1) {
264 if (semctl(sender_semid, 0, IPC_RMID) == -1)
265 warn("semctl IPC_RMID");
266 }
267 }
268
269 void
print_semid_ds(struct semid_ds * sp,mode_t mode)270 print_semid_ds(struct semid_ds *sp, mode_t mode)
271 {
272 uid_t uid = geteuid();
273 gid_t gid = getegid();
274
275 printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
276 sp->sem_perm.uid, sp->sem_perm.gid,
277 sp->sem_perm.cuid, sp->sem_perm.cgid,
278 sp->sem_perm.mode & 0777);
279
280 printf("nsems %u\n", sp->sem_nsems);
281
282 printf("otime: %s", ctime(&sp->sem_otime));
283 printf("ctime: %s", ctime(&sp->sem_ctime));
284
285 /*
286 * Sanity check a few things.
287 */
288
289 if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
290 errx(1, "uid mismatch");
291
292 if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
293 errx(1, "gid mismatch");
294
295 if ((sp->sem_perm.mode & 0777) != mode)
296 errx(1, "mode mismatch %o != %o",
297 (sp->sem_perm.mode & 0777), mode);
298 }
299
300 void
usage()301 usage()
302 {
303
304 fprintf(stderr, "usage: %s keypath\n", getprogname());
305 exit(1);
306 }
307
308 void
waiter()309 waiter()
310 {
311 struct sembuf s;
312 int semid;
313
314 if ((semid = semget(semkey, 1, 0)) == -1)
315 err(1, "waiter: semget");
316
317 /*
318 * Attempt to acquire the semaphore.
319 */
320 s.sem_num = 0;
321 s.sem_op = -1;
322 s.sem_flg = SEM_UNDO;
323
324 if (semop(semid, &s, 1) == -1)
325 err(1, "waiter: semop -1");
326
327 printf("WOO! GOT THE SEMAPHORE!\n");
328 sleep(1);
329
330 /*
331 * Release the semaphore and exit.
332 */
333 s.sem_num = 0;
334 s.sem_op = 1;
335 s.sem_flg = SEM_UNDO;
336
337 if (semop(semid, &s, 1) == -1)
338 err(1, "waiter: semop +1");
339
340 exit(0);
341 }
342