semtest.c revision 256281 
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: stable/10/tools/regression/sysvsem/semtest.c 235719 2012-05-21 07:52:46Z kevlo $
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
52int	main (int, char *[]);
53void	print_semid_ds (struct semid_ds *, mode_t);
54void	sigsys_handler (int);
55void	sigchld_handler(int);
56void	cleanup (void);
57void	waiter (void);
58void	usage (void);
59
60int	sender_semid = -1;
61pid_t	child_pid;
62int	child_count;
63int	signal_was_sigchld;
64
65key_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
74union 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
81int
82main(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
208void
209sigsys_handler(int signo)
210{
211
212	errx(1, "System V Semaphore support is not present in the kernel");
213}
214
215void
216sigchld_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
256void
257cleanup()
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
269void
270print_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
300void
301usage()
302{
303
304	fprintf(stderr, "usage: %s keypath\n", getprogname());
305	exit(1);
306}
307
308void
309waiter()
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