1 : /*
2 : +----------------------------------------------------------------------+
3 : | PHP Version 5 |
4 : +----------------------------------------------------------------------+
5 : | Copyright (c) 1997-2009 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: sysvsem.c 272374 2008-12-31 11:17:49Z sebastian $ */
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 : /* {{{ sysvsem_functions[]
60 : */
61 : zend_function_entry sysvsem_functions[] = {
62 : PHP_FE(sem_get, NULL)
63 : PHP_FE(sem_acquire, NULL)
64 : PHP_FE(sem_release, NULL)
65 : PHP_FE(sem_remove, NULL)
66 : {NULL, NULL, NULL}
67 : };
68 : /* }}} */
69 :
70 : /* {{{ sysvsem_module_entry
71 : */
72 : zend_module_entry sysvsem_module_entry = {
73 : STANDARD_MODULE_HEADER,
74 : "sysvsem",
75 : sysvsem_functions,
76 : PHP_MINIT(sysvsem),
77 : NULL,
78 : NULL,
79 : NULL,
80 : NULL,
81 : NO_VERSION_YET,
82 : STANDARD_MODULE_PROPERTIES
83 : };
84 : /* }}} */
85 :
86 : #ifdef COMPILE_DL_SYSVSEM
87 : ZEND_GET_MODULE(sysvsem)
88 : #endif
89 :
90 :
91 : THREAD_LS sysvsem_module php_sysvsem_module;
92 :
93 : /* Semaphore functions using System V semaphores. Each semaphore
94 : * actually consists of three semaphores allocated as a unit under the
95 : * same key. Semaphore 0 (SYSVSEM_SEM) is the actual semaphore, it is
96 : * initialized to max_acquire and decremented as processes acquire it.
97 : * The value of semaphore 1 (SYSVSEM_USAGE) is a count of the number
98 : * of processes using the semaphore. After calling semget(), if a
99 : * process finds that the usage count is 1, it will set the value of
100 : * SYSVSEM_SEM to max_acquire. This allows max_acquire to be set and
101 : * track the PHP code without having a global init routine or external
102 : * semaphore init code. Except see the bug regarding a race condition
103 : * php_sysvsem_get(). Semaphore 2 (SYSVSEM_SETVAL) serializes the
104 : * calls to GETVAL SYSVSEM_USAGE and SETVAL SYSVSEM_SEM. It can be
105 : * acquired only when it is zero.
106 : */
107 :
108 : #define SYSVSEM_SEM 0
109 : #define SYSVSEM_USAGE 1
110 : #define SYSVSEM_SETVAL 2
111 :
112 : /* {{{ release_sysvsem_sem
113 : */
114 : static void release_sysvsem_sem(zend_rsrc_list_entry *rsrc TSRMLS_DC)
115 1 : {
116 1 : sysvsem_sem *sem_ptr = (sysvsem_sem *)rsrc->ptr;
117 : struct sembuf sop[2];
118 1 : int opcount = 1;
119 : /*
120 : * if count == -1, semaphore has been removed
121 : * Need better way to handle this
122 : */
123 :
124 1 : if (sem_ptr->count == -1 || !sem_ptr->auto_release) {
125 1 : efree(sem_ptr);
126 1 : return;
127 : }
128 : /* Decrement the usage count. */
129 :
130 0 : sop[0].sem_num = SYSVSEM_USAGE;
131 0 : sop[0].sem_op = -1;
132 0 : sop[0].sem_flg = SEM_UNDO;
133 :
134 : /* Release the semaphore if it has been acquired but not released. */
135 :
136 0 : if (sem_ptr->count) {
137 :
138 0 : sop[1].sem_num = SYSVSEM_SEM;
139 0 : sop[1].sem_op = sem_ptr->count;
140 0 : sop[1].sem_flg = SEM_UNDO;
141 :
142 0 : opcount++;
143 : }
144 :
145 0 : semop(sem_ptr->semid, sop, opcount);
146 0 : efree(sem_ptr);
147 : }
148 : /* }}} */
149 :
150 : /* {{{ PHP_MINIT_FUNCTION
151 : */
152 : PHP_MINIT_FUNCTION(sysvsem)
153 13565 : {
154 13565 : php_sysvsem_module.le_sem = zend_register_list_destructors_ex(release_sysvsem_sem, NULL, "sysvsem", module_number);
155 13565 : return SUCCESS;
156 : }
157 : /* }}} */
158 :
159 : #define SETVAL_WANTS_PTR
160 :
161 : #if defined(_AIX)
162 : #undef SETVAL_WANTS_PTR
163 : #endif
164 :
165 : /* {{{ proto resource sem_get(int key [, int max_acquire [, int perm [, int auto_release]])
166 : Return an id for the semaphore with the given key, and allow max_acquire (default 1) processes to acquire it simultaneously */
167 : PHP_FUNCTION(sem_get)
168 1 : {
169 1 : long key, max_acquire = 1, perm = 0666, auto_release = 1;
170 : int semid;
171 : struct sembuf sop[3];
172 : int count;
173 : sysvsem_sem *sem_ptr;
174 :
175 1 : if (FAILURE == zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l|lll", &key, &max_acquire, &perm, &auto_release)) {
176 0 : RETURN_FALSE;
177 : }
178 :
179 : /* Get/create the semaphore. Note that we rely on the semaphores
180 : * being zeroed when they are created. Despite the fact that
181 : * the(?) Linux semget() man page says they are not initialized,
182 : * the kernel versions 2.0.x and 2.1.z do in fact zero them.
183 : */
184 :
185 1 : semid = semget(key, 3, perm|IPC_CREAT);
186 1 : if (semid == -1) {
187 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
188 0 : RETURN_FALSE;
189 : }
190 :
191 : /* Find out how many processes are using this semaphore. Note
192 : * that on Linux (at least) there is a race condition here because
193 : * semaphore undo on process exit is not atomic, so we could
194 : * acquire SYSVSEM_SETVAL before a crashed process has decremented
195 : * SYSVSEM_USAGE in which case count will be greater than it
196 : * should be and we won't set max_acquire. Fortunately this
197 : * doesn't actually matter in practice.
198 : */
199 :
200 : /* Wait for sem 1 to be zero . . . */
201 :
202 1 : sop[0].sem_num = SYSVSEM_SETVAL;
203 1 : sop[0].sem_op = 0;
204 1 : sop[0].sem_flg = 0;
205 :
206 : /* . . . and increment it so it becomes non-zero . . . */
207 :
208 1 : sop[1].sem_num = SYSVSEM_SETVAL;
209 1 : sop[1].sem_op = 1;
210 1 : sop[1].sem_flg = SEM_UNDO;
211 :
212 : /* . . . and increment the usage count. */
213 :
214 1 : sop[2].sem_num = SYSVSEM_USAGE;
215 1 : sop[2].sem_op = 1;
216 1 : sop[2].sem_flg = SEM_UNDO;
217 2 : while (semop(semid, sop, 3) == -1) {
218 0 : if (errno != EINTR) {
219 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed acquiring SYSVSEM_SETVAL for key 0x%lx: %s", key, strerror(errno));
220 0 : break;
221 : }
222 : }
223 :
224 : /* Get the usage count. */
225 1 : count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
226 1 : if (count == -1) {
227 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
228 : }
229 :
230 : /* If we are the only user, then take this opportunity to set the max. */
231 :
232 1 : if (count == 1) {
233 : #if HAVE_SEMUN
234 : /* This is correct for Linux which has union semun. */
235 : union semun semarg;
236 1 : semarg.val = max_acquire;
237 1 : if (semctl(semid, SYSVSEM_SEM, SETVAL, semarg) == -1) {
238 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
239 : }
240 : #elif defined(SETVAL_WANTS_PTR)
241 : /* This is correct for Solaris 2.6 which does not have union semun. */
242 : if (semctl(semid, SYSVSEM_SEM, SETVAL, &max_acquire) == -1) {
243 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
244 : }
245 : #else
246 : /* This works for i.e. AIX */
247 : if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
248 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
249 : }
250 : #endif
251 : }
252 :
253 : /* Set semaphore 1 back to zero. */
254 :
255 1 : sop[0].sem_num = SYSVSEM_SETVAL;
256 1 : sop[0].sem_op = -1;
257 1 : sop[0].sem_flg = SEM_UNDO;
258 2 : while (semop(semid, sop, 1) == -1) {
259 0 : if (errno != EINTR) {
260 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed releasing SYSVSEM_SETVAL for key 0x%lx: %s", key, strerror(errno));
261 0 : break;
262 : }
263 : }
264 :
265 1 : sem_ptr = (sysvsem_sem *) emalloc(sizeof(sysvsem_sem));
266 1 : sem_ptr->key = key;
267 1 : sem_ptr->semid = semid;
268 1 : sem_ptr->count = 0;
269 1 : sem_ptr->auto_release = auto_release;
270 :
271 1 : sem_ptr->id = ZEND_REGISTER_RESOURCE(return_value, sem_ptr, php_sysvsem_module.le_sem);
272 : }
273 : /* }}} */
274 :
275 : /* {{{ php_sysvsem_semop
276 : */
277 : static void php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
278 2 : {
279 : zval **arg_id;
280 : sysvsem_sem *sem_ptr;
281 : struct sembuf sop;
282 :
283 2 : switch(ZEND_NUM_ARGS()) {
284 : case 1:
285 2 : if (zend_get_parameters_ex(1, &arg_id)==FAILURE) {
286 0 : RETURN_FALSE;
287 : }
288 : break;
289 : default:
290 0 : WRONG_PARAM_COUNT;
291 : break;
292 : }
293 :
294 2 : ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
295 :
296 2 : if (!acquire && sem_ptr->count == 0) {
297 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "SysV semaphore %ld (key 0x%x) is not currently acquired", Z_LVAL_PP(arg_id), sem_ptr->key);
298 0 : RETURN_FALSE;
299 : }
300 :
301 2 : sop.sem_num = SYSVSEM_SEM;
302 2 : sop.sem_op = acquire ? -1 : 1;
303 2 : sop.sem_flg = SEM_UNDO;
304 :
305 4 : while (semop(sem_ptr->semid, &sop, 1) == -1) {
306 0 : if (errno != EINTR) {
307 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed to %s key 0x%x: %s", acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
308 0 : RETURN_FALSE;
309 : }
310 : }
311 :
312 2 : sem_ptr->count -= acquire ? -1 : 1;
313 2 : RETURN_TRUE;
314 : }
315 : /* }}} */
316 :
317 : /* {{{ proto bool sem_acquire(resource id)
318 : Acquires the semaphore with the given id, blocking if necessary */
319 : PHP_FUNCTION(sem_acquire)
320 1 : {
321 1 : php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
322 1 : }
323 : /* }}} */
324 :
325 : /* {{{ proto bool sem_release(resource id)
326 : Releases the semaphore with the given id */
327 : PHP_FUNCTION(sem_release)
328 1 : {
329 1 : php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
330 1 : }
331 : /* }}} */
332 :
333 : /* {{{ proto bool sem_remove(resource id)
334 : Removes semaphore from Unix systems */
335 :
336 : /*
337 : * contributed by Gavin Sherry gavin@linuxworld.com.au
338 : * Fri Mar 16 00:50:13 EST 2001
339 : */
340 :
341 : PHP_FUNCTION(sem_remove)
342 1 : {
343 : zval **arg_id;
344 : sysvsem_sem *sem_ptr;
345 : #if HAVE_SEMUN
346 : union semun un;
347 : struct semid_ds buf;
348 : #endif
349 :
350 1 : if (ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &arg_id) == FAILURE) {
351 0 : WRONG_PARAM_COUNT;
352 : }
353 :
354 1 : ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
355 :
356 : #if HAVE_SEMUN
357 1 : un.buf = &buf;
358 1 : if (semctl(sem_ptr->semid, 0, IPC_STAT, un) < 0) {
359 : #else
360 : if (semctl(sem_ptr->semid, 0, IPC_STAT, NULL) < 0) {
361 : #endif
362 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "SysV semaphore %ld does not (any longer) exist", Z_LVAL_PP(arg_id));
363 0 : RETURN_FALSE;
364 : }
365 :
366 : #if HAVE_SEMUN
367 1 : if (semctl(sem_ptr->semid, 0, IPC_RMID, un) < 0) {
368 : #else
369 : if (semctl(sem_ptr->semid, 0, IPC_RMID, NULL) < 0) {
370 : #endif
371 0 : php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for SysV sempphore %ld: %s", Z_LVAL_PP(arg_id), strerror(errno));
372 0 : RETURN_FALSE;
373 : }
374 :
375 : /* let release_sysvsem_sem know we have removed
376 : * the semaphore to avoid issues with releasing.
377 : */
378 :
379 1 : sem_ptr->count = -1;
380 1 : RETURN_TRUE;
381 : }
382 :
383 : /* }}} */
384 :
385 : #endif /* HAVE_SYSVSEM */
386 :
387 : /*
388 : * Local variables:
389 : * tab-width: 4
390 : * c-basic-offset: 4
391 : * End:
392 : * vim600: sw=4 ts=4 fdm=marker
393 : * vim<600: sw=4 ts=4
394 : */
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