1 /*
2 +----------------------------------------------------------------------+
3 | PHP Version 7 |
4 +----------------------------------------------------------------------+
5 | Copyright (c) 1997-2018 The PHP Group |
6 +----------------------------------------------------------------------+
7 | This source file is subject to version 3.01 of the PHP license, |
8 | that is bundled with this package in the file LICENSE, and is |
9 | available through the world-wide-web at the following url: |
10 | http://www.php.net/license/3_01.txt |
11 | If you did not receive a copy of the PHP license and are unable to |
12 | obtain it through the world-wide-web, please send a note to |
13 | license@php.net so we can mail you a copy immediately. |
14 +----------------------------------------------------------------------+
15 | Authors: Tom May <tom@go2net.com> |
16 | Gavin Sherry <gavin@linuxworld.com.au> |
17 +----------------------------------------------------------------------+
18 */
19
20 /* $Id$ */
21
22 /* Latest update build anc tested on Linux 2.2.14
23 *
24 * This has been built and tested on Solaris 2.6 and Linux 2.1.122.
25 * It may not compile or execute correctly on other systems.
26 *
27 * sas: Works for me on Linux 2.0.36 and FreeBSD 3.0-current
28 */
29
30 #ifdef HAVE_CONFIG_H
31 #include "config.h"
32 #endif
33
34 #include "php.h"
35
36 #if HAVE_SYSVSEM
37
38 #include <sys/types.h>
39 #include <sys/ipc.h>
40 #include <sys/sem.h>
41 #include <errno.h>
42
43 #include "php_sysvsem.h"
44
45 #if !HAVE_SEMUN
46
47 union semun {
48 int val; /* value for SETVAL */
49 struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
50 unsigned short int *array; /* array for GETALL, SETALL */
51 struct seminfo *__buf; /* buffer for IPC_INFO */
52 };
53
54 #undef HAVE_SEMUN
55 #define HAVE_SEMUN 1
56
57 #endif
58
59 /* {{{ arginfo */
60 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_get, 0, 0, 1)
61 ZEND_ARG_INFO(0, key)
62 ZEND_ARG_INFO(0, max_acquire)
63 ZEND_ARG_INFO(0, perm)
64 ZEND_ARG_INFO(0, auto_release)
65 ZEND_END_ARG_INFO()
66
67 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_acquire, 0, 0, 1)
68 ZEND_ARG_INFO(0, sem_identifier)
69 ZEND_ARG_INFO(0, nowait)
70 ZEND_END_ARG_INFO()
71
72 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_release, 0, 0, 1)
73 ZEND_ARG_INFO(0, sem_identifier)
74 ZEND_END_ARG_INFO()
75
76 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_remove, 0, 0, 1)
77 ZEND_ARG_INFO(0, sem_identifier)
78 ZEND_END_ARG_INFO()
79 /* }}} */
80
81 /* {{{ sysvsem_functions[]
82 */
83 const zend_function_entry sysvsem_functions[] = {
84 PHP_FE(sem_get, arginfo_sem_get)
85 PHP_FE(sem_acquire, arginfo_sem_acquire)
86 PHP_FE(sem_release, arginfo_sem_release)
87 PHP_FE(sem_remove, arginfo_sem_remove)
88 PHP_FE_END
89 };
90 /* }}} */
91
92 /* {{{ sysvsem_module_entry
93 */
94 zend_module_entry sysvsem_module_entry = {
95 STANDARD_MODULE_HEADER,
96 "sysvsem",
97 sysvsem_functions,
98 PHP_MINIT(sysvsem),
99 NULL,
100 NULL,
101 NULL,
102 NULL,
103 PHP_SYSVSEM_VERSION,
104 STANDARD_MODULE_PROPERTIES
105 };
106 /* }}} */
107
108 #ifdef COMPILE_DL_SYSVSEM
ZEND_GET_MODULE(sysvsem)109 ZEND_GET_MODULE(sysvsem)
110 #endif
111
112
113 THREAD_LS sysvsem_module php_sysvsem_module;
114
115 /* Semaphore functions using System V semaphores. Each semaphore
116 * actually consists of three semaphores allocated as a unit under the
117 * same key. Semaphore 0 (SYSVSEM_SEM) is the actual semaphore, it is
118 * initialized to max_acquire and decremented as processes acquire it.
119 * The value of semaphore 1 (SYSVSEM_USAGE) is a count of the number
120 * of processes using the semaphore. After calling semget(), if a
121 * process finds that the usage count is 1, it will set the value of
122 * SYSVSEM_SEM to max_acquire. This allows max_acquire to be set and
123 * track the PHP code without having a global init routine or external
124 * semaphore init code. Except see the bug regarding a race condition
125 * php_sysvsem_get(). Semaphore 2 (SYSVSEM_SETVAL) serializes the
126 * calls to GETVAL SYSVSEM_USAGE and SETVAL SYSVSEM_SEM. It can be
127 * acquired only when it is zero.
128 */
129
130 #define SYSVSEM_SEM 0
131 #define SYSVSEM_USAGE 1
132 #define SYSVSEM_SETVAL 2
133
134 /* {{{ release_sysvsem_sem
135 */
136 static void release_sysvsem_sem(zend_resource *rsrc)
137 {
138 sysvsem_sem *sem_ptr = (sysvsem_sem *)rsrc->ptr;
139 struct sembuf sop[2];
140 int opcount = 1;
141 /*
142 * if count == -1, semaphore has been removed
143 * Need better way to handle this
144 */
145
146 if (sem_ptr->count == -1 || !sem_ptr->auto_release) {
147 efree(sem_ptr);
148 return;
149 }
150 /* Decrement the usage count. */
151
152 sop[0].sem_num = SYSVSEM_USAGE;
153 sop[0].sem_op = -1;
154 sop[0].sem_flg = SEM_UNDO;
155
156 /* Release the semaphore if it has been acquired but not released. */
157
158 if (sem_ptr->count) {
159
160 sop[1].sem_num = SYSVSEM_SEM;
161 sop[1].sem_op = sem_ptr->count;
162 sop[1].sem_flg = SEM_UNDO;
163
164 opcount++;
165 }
166
167 semop(sem_ptr->semid, sop, opcount);
168 efree(sem_ptr);
169 }
170 /* }}} */
171
172 /* {{{ PHP_MINIT_FUNCTION
173 */
PHP_MINIT_FUNCTION(sysvsem)174 PHP_MINIT_FUNCTION(sysvsem)
175 {
176 php_sysvsem_module.le_sem = zend_register_list_destructors_ex(release_sysvsem_sem, NULL, "sysvsem", module_number);
177 return SUCCESS;
178 }
179 /* }}} */
180
181 #define SETVAL_WANTS_PTR
182
183 #if defined(_AIX)
184 #undef SETVAL_WANTS_PTR
185 #endif
186
187 /* {{{ proto resource sem_get(int key [, int max_acquire [, int perm [, int auto_release]])
188 Return an id for the semaphore with the given key, and allow max_acquire (default 1) processes to acquire it simultaneously */
PHP_FUNCTION(sem_get)189 PHP_FUNCTION(sem_get)
190 {
191 zend_long key, max_acquire = 1, perm = 0666, auto_release = 1;
192 int semid;
193 struct sembuf sop[3];
194 int count;
195 sysvsem_sem *sem_ptr;
196
197 if (FAILURE == zend_parse_parameters(ZEND_NUM_ARGS(), "l|lll", &key, &max_acquire, &perm, &auto_release)) {
198 RETURN_FALSE;
199 }
200
201 /* Get/create the semaphore. Note that we rely on the semaphores
202 * being zeroed when they are created. Despite the fact that
203 * the(?) Linux semget() man page says they are not initialized,
204 * the kernel versions 2.0.x and 2.1.z do in fact zero them.
205 */
206
207 semid = semget(key, 3, perm|IPC_CREAT);
208 if (semid == -1) {
209 php_error_docref(NULL, E_WARNING, "failed for key 0x" ZEND_XLONG_FMT ": %s", key, strerror(errno));
210 RETURN_FALSE;
211 }
212
213 /* Find out how many processes are using this semaphore. Note
214 * that on Linux (at least) there is a race condition here because
215 * semaphore undo on process exit is not atomic, so we could
216 * acquire SYSVSEM_SETVAL before a crashed process has decremented
217 * SYSVSEM_USAGE in which case count will be greater than it
218 * should be and we won't set max_acquire. Fortunately this
219 * doesn't actually matter in practice.
220 */
221
222 /* Wait for sem 1 to be zero . . . */
223
224 sop[0].sem_num = SYSVSEM_SETVAL;
225 sop[0].sem_op = 0;
226 sop[0].sem_flg = 0;
227
228 /* . . . and increment it so it becomes non-zero . . . */
229
230 sop[1].sem_num = SYSVSEM_SETVAL;
231 sop[1].sem_op = 1;
232 sop[1].sem_flg = SEM_UNDO;
233
234 /* . . . and increment the usage count. */
235
236 sop[2].sem_num = SYSVSEM_USAGE;
237 sop[2].sem_op = 1;
238 sop[2].sem_flg = SEM_UNDO;
239 while (semop(semid, sop, 3) == -1) {
240 if (errno != EINTR) {
241 php_error_docref(NULL, E_WARNING, "failed acquiring SYSVSEM_SETVAL for key 0x" ZEND_XLONG_FMT ": %s", key, strerror(errno));
242 break;
243 }
244 }
245
246 /* Get the usage count. */
247 count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
248 if (count == -1) {
249 php_error_docref(NULL, E_WARNING, "failed for key 0x" ZEND_XLONG_FMT ": %s", key, strerror(errno));
250 }
251
252 /* If we are the only user, then take this opportunity to set the max. */
253
254 if (count == 1) {
255 #if HAVE_SEMUN
256 /* This is correct for Linux which has union semun. */
257 union semun semarg;
258 semarg.val = max_acquire;
259 if (semctl(semid, SYSVSEM_SEM, SETVAL, semarg) == -1) {
260 php_error_docref(NULL, E_WARNING, "failed for key 0x" ZEND_XLONG_FMT ": %s", key, strerror(errno));
261 }
262 #elif defined(SETVAL_WANTS_PTR)
263 /* This is correct for Solaris 2.6 which does not have union semun. */
264 if (semctl(semid, SYSVSEM_SEM, SETVAL, &max_acquire) == -1) {
265 php_error_docref(NULL, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
266 }
267 #else
268 /* This works for i.e. AIX */
269 if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
270 php_error_docref(NULL, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
271 }
272 #endif
273 }
274
275 /* Set semaphore 1 back to zero. */
276
277 sop[0].sem_num = SYSVSEM_SETVAL;
278 sop[0].sem_op = -1;
279 sop[0].sem_flg = SEM_UNDO;
280 while (semop(semid, sop, 1) == -1) {
281 if (errno != EINTR) {
282 php_error_docref(NULL, E_WARNING, "failed releasing SYSVSEM_SETVAL for key 0x" ZEND_XLONG_FMT ": %s", key, strerror(errno));
283 break;
284 }
285 }
286
287 sem_ptr = (sysvsem_sem *) emalloc(sizeof(sysvsem_sem));
288 sem_ptr->key = key;
289 sem_ptr->semid = semid;
290 sem_ptr->count = 0;
291 sem_ptr->auto_release = auto_release;
292
293 RETVAL_RES(zend_register_resource(sem_ptr, php_sysvsem_module.le_sem));
294 sem_ptr->id = Z_RES_HANDLE_P(return_value);
295 }
296 /* }}} */
297
298 /* {{{ php_sysvsem_semop
299 */
php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS,int acquire)300 static void php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
301 {
302 zval *arg_id;
303 zend_bool nowait = 0;
304 sysvsem_sem *sem_ptr;
305 struct sembuf sop;
306
307 if (acquire) {
308 if (zend_parse_parameters(ZEND_NUM_ARGS(), "r|b", &arg_id, &nowait) == FAILURE) {
309 return;
310 }
311 } else {
312 if (zend_parse_parameters(ZEND_NUM_ARGS(), "r", &arg_id) == FAILURE) {
313 return;
314 }
315 }
316
317 if ((sem_ptr = (sysvsem_sem *)zend_fetch_resource(Z_RES_P(arg_id), "SysV semaphore", php_sysvsem_module.le_sem)) == NULL) {
318 RETURN_FALSE;
319 }
320
321 if (!acquire && sem_ptr->count == 0) {
322 php_error_docref(NULL, E_WARNING, "SysV semaphore " ZEND_LONG_FMT " (key 0x%x) is not currently acquired", Z_LVAL_P(arg_id), sem_ptr->key);
323 RETURN_FALSE;
324 }
325
326 sop.sem_num = SYSVSEM_SEM;
327 sop.sem_op = acquire ? -1 : 1;
328 sop.sem_flg = SEM_UNDO | (nowait ? IPC_NOWAIT : 0);
329
330 while (semop(sem_ptr->semid, &sop, 1) == -1) {
331 if (errno != EINTR) {
332 if (errno != EAGAIN) {
333 php_error_docref(NULL, E_WARNING, "failed to %s key 0x%x: %s", acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
334 }
335 RETURN_FALSE;
336 }
337 }
338
339 sem_ptr->count -= acquire ? -1 : 1;
340 RETURN_TRUE;
341 }
342 /* }}} */
343
344 /* {{{ proto bool sem_acquire(resource id)
345 Acquires the semaphore with the given id, blocking if necessary */
PHP_FUNCTION(sem_acquire)346 PHP_FUNCTION(sem_acquire)
347 {
348 php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
349 }
350 /* }}} */
351
352 /* {{{ proto bool sem_release(resource id)
353 Releases the semaphore with the given id */
PHP_FUNCTION(sem_release)354 PHP_FUNCTION(sem_release)
355 {
356 php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
357 }
358 /* }}} */
359
360 /* {{{ proto bool sem_remove(resource id)
361 Removes semaphore from Unix systems */
362
363 /*
364 * contributed by Gavin Sherry gavin@linuxworld.com.au
365 * Fri Mar 16 00:50:13 EST 2001
366 */
367
PHP_FUNCTION(sem_remove)368 PHP_FUNCTION(sem_remove)
369 {
370 zval *arg_id;
371 sysvsem_sem *sem_ptr;
372 #if HAVE_SEMUN
373 union semun un;
374 struct semid_ds buf;
375 #endif
376
377 if (zend_parse_parameters(ZEND_NUM_ARGS(), "r", &arg_id) == FAILURE) {
378 return;
379 }
380
381 if ((sem_ptr = (sysvsem_sem *)zend_fetch_resource(Z_RES_P(arg_id), "SysV semaphore", php_sysvsem_module.le_sem)) == NULL) {
382 RETURN_FALSE;
383 }
384
385 #if HAVE_SEMUN
386 un.buf = &buf;
387 if (semctl(sem_ptr->semid, 0, IPC_STAT, un) < 0) {
388 #else
389 if (semctl(sem_ptr->semid, 0, IPC_STAT, NULL) < 0) {
390 #endif
391 php_error_docref(NULL, E_WARNING, "SysV semaphore " ZEND_LONG_FMT " does not (any longer) exist", Z_LVAL_P(arg_id));
392 RETURN_FALSE;
393 }
394
395 #if HAVE_SEMUN
396 if (semctl(sem_ptr->semid, 0, IPC_RMID, un) < 0) {
397 #else
398 if (semctl(sem_ptr->semid, 0, IPC_RMID, NULL) < 0) {
399 #endif
400 php_error_docref(NULL, E_WARNING, "failed for SysV sempphore " ZEND_LONG_FMT ": %s", Z_LVAL_P(arg_id), strerror(errno));
401 RETURN_FALSE;
402 }
403
404 /* let release_sysvsem_sem know we have removed
405 * the semaphore to avoid issues with releasing.
406 */
407
408 sem_ptr->count = -1;
409 RETURN_TRUE;
410 }
411
412 /* }}} */
413
414 #endif /* HAVE_SYSVSEM */
415
416 /*
417 * Local variables:
418 * tab-width: 4
419 * c-basic-offset: 4
420 * End:
421 * vim600: sw=4 ts=4 fdm=marker
422 * vim<600: sw=4 ts=4
423 */
424
