semtest.c revision 101902 
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 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *	This product includes software developed by the NetBSD
20 *	Foundation, Inc. and its contributors.
21 * 4. Neither the name of The NetBSD Foundation nor the names of its
22 *    contributors may be used to endorse or promote products derived
23 *    from this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
26 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 * POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Obtained from: $NetBSD: semtest.c,v 1.4 2002/07/20 08:36:25 grant Exp $
38 * $FreeBSD: head/tools/regression/sysvsem/semtest.c 101902 2002-08-15 06:34:37Z alfred $
39 */
40
41/*
42 * Test the SVID-compatible Semaphore facility.
43 */
44
45#include <sys/param.h>
46#include <sys/ipc.h>
47#include <sys/sem.h>
48#include <sys/wait.h>
49
50#include <err.h>
51#include <errno.h>
52#include <signal.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <time.h>
57#include <unistd.h>
58
59int	main (int, char *[]);
60void	print_semid_ds (struct semid_ds *, mode_t);
61void	sigsys_handler (int);
62void	sigchld_handler(int);
63void	cleanup (void);
64void	waiter (void);
65void	usage (void);
66
67int	sender_semid = -1;
68pid_t	child_pid;
69int	child_count;
70int	signal_was_sigchld;
71
72key_t	semkey;
73
74/*
75 * This is the original semun union used by the sysvsem utility.
76 * It is deliberately kept here under #if 0'ed condition for future
77 * reference. PLEASE DO NOT REMOVE.  The {SET,GET}ALL in FreeBSD
78 * are signed values, so the default version in sys/sem.h suffices.
79 */
80#if 0
81union semun {
82	int	val;		/* value for SETVAL */
83	struct	semid_ds *buf;	/* buffer for IPC_{STAT,SET} */
84	u_short	*array;		/* array for GETALL & SETALL */
85};
86#endif
87
88int
89main(int argc, char *argv[])
90{
91	struct sigaction sa;
92	union semun sun;
93	struct semid_ds s_ds;
94	sigset_t sigmask;
95	int i;
96
97	if (argc != 2)
98		usage();
99
100	/*
101	 * Install a SIGSYS handler so that we can exit gracefully if
102	 * System V Semaphore support isn't in the kernel.
103	 */
104	sa.sa_handler = sigsys_handler;
105	sigemptyset(&sa.sa_mask);
106	sa.sa_flags = 0;
107	if (sigaction(SIGSYS, &sa, NULL) == -1)
108		err(1, "sigaction SIGSYS");
109
110	/*
111	 * Install and SIGCHLD handler to deal with all possible exit
112	 * conditions of the receiver.
113	 */
114	sa.sa_handler = sigchld_handler;
115	sigemptyset(&sa.sa_mask);
116	sa.sa_flags = 0;
117	if (sigaction(SIGCHLD, &sa, NULL) == -1)
118		err(1, "sigaction SIGCHLD");
119
120	semkey = ftok(argv[1], 4160);
121
122	/*
123	 * Initialize child_pid to ourselves to that the cleanup function
124	 * works before we create the receiver.
125	 */
126	child_pid = getpid();
127
128	/*
129	 * Make sure that when the sender exits, the message queue is
130	 * removed.
131	 */
132	if (atexit(cleanup) == -1)
133		err(1, "atexit");
134
135	if ((sender_semid = semget(semkey, 1, IPC_CREAT | 0640)) == -1)
136		err(1, "semget");
137
138
139	sun.buf = &s_ds;
140	if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
141		err(1, "semctl IPC_STAT");
142
143	print_semid_ds(&s_ds, 0640);
144
145	s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;
146
147	sun.buf = &s_ds;
148	if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
149		err(1, "semctl IPC_SET");
150
151	memset(&s_ds, 0, sizeof(s_ds));
152
153	sun.buf = &s_ds;
154	if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
155		err(1, "semctl IPC_STAT");
156
157	if ((s_ds.sem_perm.mode & 0777) != 0600)
158		err(1, "IPC_SET of mode didn't hold");
159
160	print_semid_ds(&s_ds, 0600);
161
162	for (child_count = 0; child_count < 5; child_count++) {
163		switch ((child_pid = fork())) {
164		case -1:
165			err(1, "fork");
166			/* NOTREACHED */
167
168		case 0:
169			waiter();
170			break;
171
172		default:
173			break;
174		}
175	}
176
177	/*
178	 * Wait for all of the waiters to be attempting to acquire the
179	 * semaphore.
180	 */
181	for (;;) {
182		i = semctl(sender_semid, 0, GETNCNT);
183		if (i == -1)
184			err(1, "semctl GETNCNT");
185		if (i == 5)
186			break;
187	}
188
189	/*
190	 * Now set the thundering herd in motion by initializing the
191	 * semaphore to the value 1.
192	 */
193	sun.val = 1;
194	if (semctl(sender_semid, 0, SETVAL, sun) == -1)
195		err(1, "sender: semctl SETVAL to 1");
196
197	/*
198	 * Suspend forever; when we get SIGCHLD, the handler will exit.
199	 */
200	sigemptyset(&sigmask);
201	for (;;) {
202		(void) sigsuspend(&sigmask);
203		if (signal_was_sigchld)
204			signal_was_sigchld = 0;
205		else
206			break;
207	}
208
209	/*
210	 * ...and any other signal is an unexpected error.
211	 */
212	errx(1, "sender: received unexpected signal");
213}
214
215void
216sigsys_handler(int signo)
217{
218
219	errx(1, "System V Semaphore support is not present in the kernel");
220}
221
222void
223sigchld_handler(int signo)
224{
225	union semun sun;
226	struct semid_ds s_ds;
227	int cstatus;
228
229	/*
230	 * Reap the child; if it exited successfully, then we're on the
231	 * right track!
232	 */
233	if (wait(&cstatus) == -1)
234		err(1, "wait");
235
236	if (WIFEXITED(cstatus) == 0)
237		errx(1, "receiver exited abnormally");
238
239	if (WEXITSTATUS(cstatus) != 0)
240		errx(1, "receiver exited with status %d",
241		    WEXITSTATUS(cstatus));
242
243	/*
244	 * If we get here, the child has exited normally, and we should
245	 * decrement the child count.  If the child_count reaches 0, we
246	 * should exit.
247	 */
248
249	sun.buf = &s_ds;
250	if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
251		err(1, "semctl IPC_STAT");
252
253	print_semid_ds(&s_ds, 0600);
254
255	if (--child_count != 0) {
256		signal_was_sigchld = 1;
257		return;
258	}
259
260	exit(0);
261}
262
263void
264cleanup()
265{
266
267	/*
268	 * If we're the sender, and it exists, remove the message queue.
269	 */
270	if (child_pid != 0 && sender_semid != -1) {
271		if (semctl(sender_semid, 0, IPC_RMID) == -1)
272			warn("semctl IPC_RMID");
273	}
274}
275
276void
277print_semid_ds(struct semid_ds *sp, mode_t mode)
278{
279	uid_t uid = geteuid();
280	gid_t gid = getegid();
281
282	printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
283	    sp->sem_perm.uid, sp->sem_perm.gid,
284	    sp->sem_perm.cuid, sp->sem_perm.cgid,
285	    sp->sem_perm.mode & 0777);
286
287	printf("nsems %u\n", sp->sem_nsems);
288
289	printf("otime: %s", ctime(&sp->sem_otime));
290	printf("ctime: %s", ctime(&sp->sem_ctime));
291
292	/*
293	 * Sanity check a few things.
294	 */
295
296	if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
297		errx(1, "uid mismatch");
298
299	if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
300		errx(1, "gid mismatch");
301
302	if ((sp->sem_perm.mode & 0777) != mode)
303		errx(1, "mode mismatch %o != %o",
304		    (sp->sem_perm.mode & 0777), mode);
305}
306
307void
308usage()
309{
310
311	fprintf(stderr, "usage: %s keypath\n", getprogname());
312	exit(1);
313}
314
315void
316waiter()
317{
318	struct sembuf s;
319	int semid;
320
321	if ((semid = semget(semkey, 1, 0)) == -1)
322		err(1, "waiter: semget");
323
324	/*
325	 * Attempt to acquire the semaphore.
326	 */
327	s.sem_num = 0;
328	s.sem_op = -1;
329	s.sem_flg = SEM_UNDO;
330
331	if (semop(semid, &s, 1) == -1)
332		err(1, "waiter: semop -1");
333
334	printf("WOO!  GOT THE SEMAPHORE!\n");
335	sleep(1);
336
337	/*
338	 * Release the semaphore and exit.
339	 */
340	s.sem_num = 0;
341	s.sem_op = 1;
342	s.sem_flg = SEM_UNDO;
343
344	if (semop(semid, &s, 1) == -1)
345		err(1, "waiter: semop +1");
346
347	exit(0);
348}
349