xref: /freebsd/tests/sys/fifo/fifo_open.c (revision d6b92ffa) 
1 /*-
2  * Copyright (c) 2005 Robert N. M. Watson
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 
29 #include <sys/types.h>
30 #include <sys/stat.h>
31 #include <sys/wait.h>
32 
33 #include <err.h>
34 #include <errno.h>
35 #include <fcntl.h>
36 #include <limits.h>
37 #include <signal.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42 
43 /*
44  * Regression test to exercise various POSIX-defined parts of fifo behavior
45  * described for open(2):
46  *
47  * O_NONBLOCK
48  * When opening a FIFO with O_RDONLY or O_WRONLY set:
49  *
50  * - If O_NONBLOCK is set, an open() for reading-only shall return without
51  *   delay. An open() for writing-only shall return an error if no process
52  *   currently has the file open for reading.
53  *
54  * - If O_NONBLOCK is clear, an open() for reading-only shall block the
55  *   calling thread until a thread opens the file for writing. An open()
56  *   for writing-only shall block the calling thread until a thread opens
57  *   the file for reading.
58  *
59  * When opening a block special or character special file that supports
60  * non-blocking opens:
61  *
62  * - If O_NONBLOCK is set, the open() function shall return without blocking
63  *   for the device to be ready or available. Subsequent behavior of the
64  *   device is device-specific.
65  *
66  * - If O_NONBLOCK is clear, the open() function shall block the calling
67  *   thread until the device is ready or available before returning.
68  *
69  * Special errors:
70  *
71  * [ENXIO]
72  * O_NONBLOCK is set, the named file is a FIFO, O_WRONLY is set, and no
73  * process has the file open for reading.
74  */
75 
76 /*
77  * In order to test blocking/non-blocking behavior, test processes must
78  * potentially block themselves until released.  As bugs in blocking result
79  * in processes that won't un-block, we must sacrifice a process to the task,
80  * watching and potentially killing it after a time-out.  The main test
81  * process is never used to open or act directly on a fifo (other than to
82  * create or unlink it) in order to avoid the main test process being
83  * blocked.
84  */
85 
86 /*
87  * All activity occurs within a temporary directory created early in the
88  * test.
89  */
90 static char	temp_dir[PATH_MAX];
91 
92 static void __unused
93 atexit_temp_dir(void)
94 {
95 
96 	rmdir(temp_dir);
97 }
98 
99 /*
100  * Run a function in a particular test process.
101  */
102 static int
103 run_in_process(int (*func)(void), pid_t *pidp, const char *errstr)
104 {
105 	pid_t pid;
106 
107 	pid = fork();
108 	if (pid < 0) {
109 		warn("%s: run_in_process: fork", errstr);
110 		return (-1);
111 	}
112 
113 	if (pid == 0)
114 		exit(func());
115 
116 	if (pidp != NULL)
117 		*pidp = pid;
118 
119 	return (0);
120 }
121 
122 /*
123  * Wait for a process on a timeout, and if the timeout expires, kill the
124  * process.  Test each second rather than waiting the full timeout at once to
125  * minimize the amount of time spent hanging around unnecessarily.
126  */
127 static int
128 wait_and_timeout(pid_t pid, int timeout, int *status, const char *errstr)
129 {
130 	pid_t wpid;
131 	int i;
132 
133 	/*
134 	 * Count up to the timeout, but do a non-hanging waitpid() after each
135 	 * second so we can avoid waiting a lot of extra time.
136 	 */
137 	for (i = 0; i < timeout; i++) {
138 		wpid = waitpid(pid, status, WNOHANG);
139 		if (wpid < 0) {
140 			warn("%s: wait_and_timeout: waitpid %d", errstr, pid);
141 			return (-1);
142 		}
143 
144 		if (wpid == pid)
145 			return (0);
146 
147 		sleep(1);
148 	}
149 
150 	wpid = waitpid(pid, status, WNOHANG);
151 	if (wpid < 0) {
152 		warn("%s: wait_and_timeout: waitpid %d", errstr, pid);
153 		return (-1);
154 	}
155 
156 	if (wpid == pid)
157 		return (0);
158 
159 	if (kill(pid, SIGTERM) < 0) {
160 		warn("%s: wait_and_timeout: kill %d", errstr, pid);
161 		return (-1);
162 	}
163 
164 	wpid = waitpid(pid, status, 0);
165 	if (wpid < 0) {
166 		warn("%s: wait_and_timeout: waitpid %d", errstr, pid);
167 		return (-1);
168 	}
169 
170 	if (wpid != pid) {
171 		warn("%s: waitpid: returned %d not %d", errstr, wpid, pid);
172 		return (-1);
173 	}
174 
175 	warnx("%s: process blocked", errstr);
176 	return (-1);
177 }
178 
179 static int
180 non_blocking_open_reader(void)
181 {
182 	int fd;
183 
184 	fd = open("testfifo", O_RDONLY | O_NONBLOCK);
185 	if (fd < 0)
186 		return (errno);
187 	close(fd);
188 
189 	return (0);
190 }
191 
192 static int
193 non_blocking_open_writer(void)
194 {
195 	int fd;
196 
197 	fd = open("testfifo", O_WRONLY | O_NONBLOCK);
198 	if (fd < 0)
199 		return (errno);
200 	close(fd);
201 
202 	return (0);
203 }
204 
205 static int
206 blocking_open_reader(void)
207 {
208 	int fd;
209 
210 	fd = open("testfifo", O_RDONLY);
211 	if (fd < 0)
212 		return (errno);
213 	close(fd);
214 
215 	return (0);
216 }
217 
218 static int
219 blocking_open_writer(void)
220 {
221 	int fd;
222 
223 	fd = open("testfifo", O_WRONLY);
224 	if (fd < 0)
225 		return (errno);
226 	close(fd);
227 
228 	return (0);
229 }
230 
231 static void
232 test_blocking_reader(void)
233 {
234 	pid_t reader_pid, writer_pid, wpid;
235 	int error, status;
236 
237 	if (mkfifo("testfifo", 0600) < 0)
238 		err(-1, "test_blocking_reader: mkfifo: testfifo");
239 
240 	/*
241 	 * Block a process in opening the fifo.
242 	 */
243 	if (run_in_process(blocking_open_reader, &reader_pid,
244 	    "test_blocking_reader: blocking_open_reader") < 0) {
245 		(void)unlink("testfifo");
246 		exit(-1);
247 	}
248 
249 	/*
250 	 * Test that it blocked.
251 	 */
252 	sleep(5);
253 	wpid = waitpid(reader_pid, &status, WNOHANG);
254 	if (wpid < 0) {
255 		error = errno;
256 		(void)unlink("testfifo");
257 		errno = error;
258 		err(-1, "test_blocking_reader: waitpid %d", reader_pid);
259 	}
260 
261 	if (wpid != 0 && wpid != reader_pid) {
262 		(void)unlink("testfifo");
263 		errx(-1, "test_blocking_reader: waitpid %d returned %d",
264 		    reader_pid, wpid);
265 	}
266 
267 	if (wpid == reader_pid) {
268 		(void)unlink("testfifo");
269 		errx(-1, "test_blocking_reader: blocking child didn't "
270 		    "block");
271 	}
272 
273 	/*
274 	 * Unblock the blocking reader.
275 	 */
276 	if (run_in_process(blocking_open_writer, &writer_pid,
277 	    "test_blocking_reader: blocking_open_writer") < 0) {
278 		(void)unlink("testfifo");
279 		(void)kill(reader_pid, SIGTERM);
280 		(void)waitpid(reader_pid, &status, 0);
281 		exit(-1);
282 	}
283 
284 	/*
285 	 * Make sure both processes exited quickly (<1 second) to make sure
286 	 * they didn't block, and GC.
287 	 */
288 	if (wait_and_timeout(reader_pid, 1, &status,
289 	    "test_blocking_reader: blocking_open_reader") < 0) {
290 		(void)unlink("testinfo");
291 		(void)kill(reader_pid, SIGTERM);
292 		(void)kill(writer_pid, SIGTERM);
293 		exit(-1);
294 	}
295 
296 	if (wait_and_timeout(writer_pid, 1, &status,
297 	    "test_blocking_reader: blocking_open_writer") < 0) {
298 		(void)unlink("testinfo");
299 		(void)kill(writer_pid, SIGTERM);
300 		exit(-1);
301 	}
302 
303 	if (unlink("testfifo") < 0)
304 		err(-1, "test_blocking_reader: unlink: testfifo");
305 }
306 static void
307 test_blocking_writer(void)
308 {
309 	pid_t reader_pid, writer_pid, wpid;
310 	int error, status;
311 
312 	if (mkfifo("testfifo", 0600) < 0)
313 		err(-1, "test_blocking_writer: mkfifo: testfifo");
314 
315 	/*
316 	 * Block a process in opening the fifo.
317 	 */
318 	if (run_in_process(blocking_open_writer, &writer_pid,
319 	    "test_blocking_writer: blocking_open_writer") < 0) {
320 		(void)unlink("testfifo");
321 		exit(-1);
322 	}
323 
324 	/*
325 	 * Test that it blocked.
326 	 */
327 	sleep(5);
328 	wpid = waitpid(writer_pid, &status, WNOHANG);
329 	if (wpid < 0) {
330 		error = errno;
331 		(void)unlink("testfifo");
332 		errno = error;
333 		err(-1, "test_blocking_writer: waitpid %d", writer_pid);
334 	}
335 
336 	if (wpid != 0 && wpid != writer_pid) {
337 		(void)unlink("testfifo");
338 		errx(-1, "test_blocking_writer: waitpid %d returned %d",
339 		    writer_pid, wpid);
340 	}
341 
342 	if (wpid == writer_pid) {
343 		(void)unlink("testfifo");
344 		errx(-1, "test_blocking_writer: blocking child didn't "
345 		    "block");
346 	}
347 
348 	/*
349 	 * Unblock the blocking writer.
350 	 */
351 	if (run_in_process(blocking_open_reader, &reader_pid,
352 	    "test_blocking_writer: blocking_open_reader") < 0) {
353 		(void)unlink("testfifo");
354 		(void)kill(writer_pid, SIGTERM);
355 		(void)waitpid(writer_pid, &status, 0);
356 		exit(-1);
357 	}
358 
359 	/*
360 	 * Make sure both processes exited quickly (<1 second) to make sure
361 	 * they didn't block, and GC.
362 	 */
363 	if (wait_and_timeout(writer_pid, 1, &status,
364 	    "test_blocking_writer: blocking_open_writer") < 0) {
365 		(void)unlink("testinfo");
366 		(void)kill(writer_pid, SIGTERM);
367 		(void)kill(reader_pid, SIGTERM);
368 		(void)waitpid(writer_pid, &status, 0);
369 		(void)waitpid(reader_pid, &status, 0);
370 		exit(-1);
371 	}
372 
373 	if (wait_and_timeout(reader_pid, 1, &status,
374 	    "test_blocking_writer: blocking_open_reader") < 0) {
375 		(void)unlink("testinfo");
376 		(void)kill(reader_pid, SIGTERM);
377 		(void)waitpid(reader_pid, &status, 0);
378 		exit(-1);
379 	}
380 
381 	if (unlink("testfifo") < 0)
382 		err(-1, "test_blocking_writer: unlink: testfifo");
383 }
384 
385 static void
386 test_non_blocking_reader(void)
387 {
388 	int status;
389 	pid_t pid;
390 
391 	if (mkfifo("testfifo", 0600) < 0)
392 		err(-1, "test_non_blocking_reader: mkfifo: testfifo");
393 
394 	if (run_in_process(non_blocking_open_reader, &pid,
395 	    "test_non_blocking_reader: non_blocking_open_reader") < 0) {
396 		(void)unlink("testfifo");
397 		exit(-1);
398 	}
399 
400 	status = -1;
401 	if (wait_and_timeout(pid, 5, &status,
402 	    "test_non_blocking_reader: non_blocking_open_reader") < 0) {
403 		(void)unlink("testfifo");
404 		exit(-1);
405 	}
406 
407 	if (WEXITSTATUS(status) != 0) {
408 		(void)unlink("testfifo");
409 		errno = WEXITSTATUS(status);
410 		err(-1, "test_non_blocking_reader: "
411 		    "non_blocking_open_reader: open: testfifo");
412 	}
413 
414 	if (unlink("testfifo") < 0)
415 		err(-1, "test_non_blocking_reader: unlink: testfifo");
416 }
417 
418 static void
419 test_non_blocking_writer(void)
420 {
421 	int status;
422 	pid_t pid;
423 
424 	if (mkfifo("testfifo", 0600) < 0)
425 		err(-1, "test_non_blocking_writer: mkfifo: testfifo");
426 
427 	if (run_in_process(non_blocking_open_writer, &pid,
428 	    "test_non_blocking_writer: non_blocking_open_writer") < 0) {
429 		(void)unlink("testfifo");
430 		exit(-1);
431 	}
432 
433 	status = -1;
434 	if (wait_and_timeout(pid, 5, &status,
435 	    "test_non_blocking_writer: non_blocking_open_writer") < 0) {
436 		(void)unlink("testfifo");
437 		exit(-1);
438 	}
439 
440 	if (WEXITSTATUS(status) != ENXIO) {
441 		(void)unlink("testfifo");
442 
443 		errno = WEXITSTATUS(status);
444 		if (errno == 0)
445 			errx(-1, "test_non_blocking_writer: "
446 			    "non_blocking_open_writer: open succeeded");
447 		err(-1, "test_non_blocking_writer: "
448 		    "non_blocking_open_writer: open: testfifo");
449 	}
450 
451 	if (unlink("testfifo") < 0)
452 		err(-1, "test_non_blocking_writer: unlink: testfifo");
453 }
454 
455 int
456 main(void)
457 {
458 
459 	if (geteuid() != 0)
460 		errx(-1, "must be run as root");
461 
462 	strcpy(temp_dir, "fifo_open.XXXXXXXXXXX");
463 	if (mkdtemp(temp_dir) == NULL)
464 		err(-1, "mkdtemp");
465 	if (chdir(temp_dir) < 0)
466 		err(-1, "chdir: %s", temp_dir);
467 	atexit(atexit_temp_dir);
468 
469 	test_non_blocking_reader();
470 	test_non_blocking_writer();
471 
472 	test_blocking_reader();
473 	test_blocking_writer();
474 
475 	return (0);
476 }
477