1 /*
2 +----------------------------------------------------------------------+
3 | PHP Version 5 |
4 +----------------------------------------------------------------------+
5 | Copyright (c) 1997-2014 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_END_ARG_INFO()
70
71 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_release, 0, 0, 1)
72 ZEND_ARG_INFO(0, sem_identifier)
73 ZEND_END_ARG_INFO()
74
75 ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_remove, 0, 0, 1)
76 ZEND_ARG_INFO(0, sem_identifier)
77 ZEND_END_ARG_INFO()
78 /* }}} */
79
80 /* {{{ sysvsem_functions[]
81 */
82 const zend_function_entry sysvsem_functions[] = {
83 PHP_FE(sem_get, arginfo_sem_get)
84 PHP_FE(sem_acquire, arginfo_sem_acquire)
85 PHP_FE(sem_release, arginfo_sem_release)
86 PHP_FE(sem_remove, arginfo_sem_remove)
87 PHP_FE_END
88 };
89 /* }}} */
90
91 /* {{{ sysvsem_module_entry
92 */
93 zend_module_entry sysvsem_module_entry = {
94 STANDARD_MODULE_HEADER,
95 "sysvsem",
96 sysvsem_functions,
97 PHP_MINIT(sysvsem),
98 NULL,
99 NULL,
100 NULL,
101 NULL,
102 NO_VERSION_YET,
103 STANDARD_MODULE_PROPERTIES
104 };
105 /* }}} */
106
107 #ifdef COMPILE_DL_SYSVSEM
ZEND_GET_MODULE(sysvsem)108 ZEND_GET_MODULE(sysvsem)
109 #endif
110
111
112 THREAD_LS sysvsem_module php_sysvsem_module;
113
114 /* Semaphore functions using System V semaphores. Each semaphore
115 * actually consists of three semaphores allocated as a unit under the
116 * same key. Semaphore 0 (SYSVSEM_SEM) is the actual semaphore, it is
117 * initialized to max_acquire and decremented as processes acquire it.
118 * The value of semaphore 1 (SYSVSEM_USAGE) is a count of the number
119 * of processes using the semaphore. After calling semget(), if a
120 * process finds that the usage count is 1, it will set the value of
121 * SYSVSEM_SEM to max_acquire. This allows max_acquire to be set and
122 * track the PHP code without having a global init routine or external
123 * semaphore init code. Except see the bug regarding a race condition
124 * php_sysvsem_get(). Semaphore 2 (SYSVSEM_SETVAL) serializes the
125 * calls to GETVAL SYSVSEM_USAGE and SETVAL SYSVSEM_SEM. It can be
126 * acquired only when it is zero.
127 */
128
129 #define SYSVSEM_SEM 0
130 #define SYSVSEM_USAGE 1
131 #define SYSVSEM_SETVAL 2
132
133 /* {{{ release_sysvsem_sem
134 */
135 static void release_sysvsem_sem(zend_rsrc_list_entry *rsrc TSRMLS_DC)
136 {
137 sysvsem_sem *sem_ptr = (sysvsem_sem *)rsrc->ptr;
138 struct sembuf sop[2];
139 int opcount = 1;
140 /*
141 * if count == -1, semaphore has been removed
142 * Need better way to handle this
143 */
144
145 if (sem_ptr->count == -1 || !sem_ptr->auto_release) {
146 efree(sem_ptr);
147 return;
148 }
149 /* Decrement the usage count. */
150
151 sop[0].sem_num = SYSVSEM_USAGE;
152 sop[0].sem_op = -1;
153 sop[0].sem_flg = SEM_UNDO;
154
155 /* Release the semaphore if it has been acquired but not released. */
156
157 if (sem_ptr->count) {
158
159 sop[1].sem_num = SYSVSEM_SEM;
160 sop[1].sem_op = sem_ptr->count;
161 sop[1].sem_flg = SEM_UNDO;
162
163 opcount++;
164 }
165
166 semop(sem_ptr->semid, sop, opcount);
167 efree(sem_ptr);
168 }
169 /* }}} */
170
171 /* {{{ PHP_MINIT_FUNCTION
172 */
PHP_MINIT_FUNCTION(sysvsem)173 PHP_MINIT_FUNCTION(sysvsem)
174 {
175 php_sysvsem_module.le_sem = zend_register_list_destructors_ex(release_sysvsem_sem, NULL, "sysvsem", module_number);
176 return SUCCESS;
177 }
178 /* }}} */
179
180 #define SETVAL_WANTS_PTR
181
182 #if defined(_AIX)
183 #undef SETVAL_WANTS_PTR
184 #endif
185
186 /* {{{ proto resource sem_get(int key [, int max_acquire [, int perm [, int auto_release]])
187 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)188 PHP_FUNCTION(sem_get)
189 {
190 long key, max_acquire = 1, perm = 0666, auto_release = 1;
191 int semid;
192 struct sembuf sop[3];
193 int count;
194 sysvsem_sem *sem_ptr;
195
196 if (FAILURE == zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l|lll", &key, &max_acquire, &perm, &auto_release)) {
197 RETURN_FALSE;
198 }
199
200 /* Get/create the semaphore. Note that we rely on the semaphores
201 * being zeroed when they are created. Despite the fact that
202 * the(?) Linux semget() man page says they are not initialized,
203 * the kernel versions 2.0.x and 2.1.z do in fact zero them.
204 */
205
206 semid = semget(key, 3, perm|IPC_CREAT);
207 if (semid == -1) {
208 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
209 RETURN_FALSE;
210 }
211
212 /* Find out how many processes are using this semaphore. Note
213 * that on Linux (at least) there is a race condition here because
214 * semaphore undo on process exit is not atomic, so we could
215 * acquire SYSVSEM_SETVAL before a crashed process has decremented
216 * SYSVSEM_USAGE in which case count will be greater than it
217 * should be and we won't set max_acquire. Fortunately this
218 * doesn't actually matter in practice.
219 */
220
221 /* Wait for sem 1 to be zero . . . */
222
223 sop[0].sem_num = SYSVSEM_SETVAL;
224 sop[0].sem_op = 0;
225 sop[0].sem_flg = 0;
226
227 /* . . . and increment it so it becomes non-zero . . . */
228
229 sop[1].sem_num = SYSVSEM_SETVAL;
230 sop[1].sem_op = 1;
231 sop[1].sem_flg = SEM_UNDO;
232
233 /* . . . and increment the usage count. */
234
235 sop[2].sem_num = SYSVSEM_USAGE;
236 sop[2].sem_op = 1;
237 sop[2].sem_flg = SEM_UNDO;
238 while (semop(semid, sop, 3) == -1) {
239 if (errno != EINTR) {
240 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed acquiring SYSVSEM_SETVAL for key 0x%lx: %s", key, strerror(errno));
241 break;
242 }
243 }
244
245 /* Get the usage count. */
246 count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
247 if (count == -1) {
248 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
249 }
250
251 /* If we are the only user, then take this opportunity to set the max. */
252
253 if (count == 1) {
254 #if HAVE_SEMUN
255 /* This is correct for Linux which has union semun. */
256 union semun semarg;
257 semarg.val = max_acquire;
258 if (semctl(semid, SYSVSEM_SEM, SETVAL, semarg) == -1) {
259 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
260 }
261 #elif defined(SETVAL_WANTS_PTR)
262 /* This is correct for Solaris 2.6 which does not have union semun. */
263 if (semctl(semid, SYSVSEM_SEM, SETVAL, &max_acquire) == -1) {
264 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
265 }
266 #else
267 /* This works for i.e. AIX */
268 if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
269 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
270 }
271 #endif
272 }
273
274 /* Set semaphore 1 back to zero. */
275
276 sop[0].sem_num = SYSVSEM_SETVAL;
277 sop[0].sem_op = -1;
278 sop[0].sem_flg = SEM_UNDO;
279 while (semop(semid, sop, 1) == -1) {
280 if (errno != EINTR) {
281 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed releasing SYSVSEM_SETVAL for key 0x%lx: %s", key, strerror(errno));
282 break;
283 }
284 }
285
286 sem_ptr = (sysvsem_sem *) emalloc(sizeof(sysvsem_sem));
287 sem_ptr->key = key;
288 sem_ptr->semid = semid;
289 sem_ptr->count = 0;
290 sem_ptr->auto_release = auto_release;
291
292 sem_ptr->id = ZEND_REGISTER_RESOURCE(return_value, sem_ptr, php_sysvsem_module.le_sem);
293 }
294 /* }}} */
295
296 /* {{{ php_sysvsem_semop
297 */
php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS,int acquire)298 static void php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
299 {
300 zval *arg_id;
301 sysvsem_sem *sem_ptr;
302 struct sembuf sop;
303
304 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "r", &arg_id) == FAILURE) {
305 return;
306 }
307
308 ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, &arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
309
310 if (!acquire && sem_ptr->count == 0) {
311 php_error_docref(NULL TSRMLS_CC, E_WARNING, "SysV semaphore %ld (key 0x%x) is not currently acquired", Z_LVAL_P(arg_id), sem_ptr->key);
312 RETURN_FALSE;
313 }
314
315 sop.sem_num = SYSVSEM_SEM;
316 sop.sem_op = acquire ? -1 : 1;
317 sop.sem_flg = SEM_UNDO;
318
319 while (semop(sem_ptr->semid, &sop, 1) == -1) {
320 if (errno != EINTR) {
321 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed to %s key 0x%x: %s", acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
322 RETURN_FALSE;
323 }
324 }
325
326 sem_ptr->count -= acquire ? -1 : 1;
327 RETURN_TRUE;
328 }
329 /* }}} */
330
331 /* {{{ proto bool sem_acquire(resource id)
332 Acquires the semaphore with the given id, blocking if necessary */
PHP_FUNCTION(sem_acquire)333 PHP_FUNCTION(sem_acquire)
334 {
335 php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
336 }
337 /* }}} */
338
339 /* {{{ proto bool sem_release(resource id)
340 Releases the semaphore with the given id */
PHP_FUNCTION(sem_release)341 PHP_FUNCTION(sem_release)
342 {
343 php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
344 }
345 /* }}} */
346
347 /* {{{ proto bool sem_remove(resource id)
348 Removes semaphore from Unix systems */
349
350 /*
351 * contributed by Gavin Sherry gavin@linuxworld.com.au
352 * Fri Mar 16 00:50:13 EST 2001
353 */
354
PHP_FUNCTION(sem_remove)355 PHP_FUNCTION(sem_remove)
356 {
357 zval *arg_id;
358 sysvsem_sem *sem_ptr;
359 #if HAVE_SEMUN
360 union semun un;
361 struct semid_ds buf;
362 #endif
363
364 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "r", &arg_id) == FAILURE) {
365 return;
366 }
367
368 ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, &arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
369
370 #if HAVE_SEMUN
371 un.buf = &buf;
372 if (semctl(sem_ptr->semid, 0, IPC_STAT, un) < 0) {
373 #else
374 if (semctl(sem_ptr->semid, 0, IPC_STAT, NULL) < 0) {
375 #endif
376 php_error_docref(NULL TSRMLS_CC, E_WARNING, "SysV semaphore %ld does not (any longer) exist", Z_LVAL_P(arg_id));
377 RETURN_FALSE;
378 }
379
380 #if HAVE_SEMUN
381 if (semctl(sem_ptr->semid, 0, IPC_RMID, un) < 0) {
382 #else
383 if (semctl(sem_ptr->semid, 0, IPC_RMID, NULL) < 0) {
384 #endif
385 php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for SysV sempphore %ld: %s", Z_LVAL_P(arg_id), strerror(errno));
386 RETURN_FALSE;
387 }
388
389 /* let release_sysvsem_sem know we have removed
390 * the semaphore to avoid issues with releasing.
391 */
392
393 sem_ptr->count = -1;
394 RETURN_TRUE;
395 }
396
397 /* }}} */
398
399 #endif /* HAVE_SYSVSEM */
400
401 /*
402 * Local variables:
403 * tab-width: 4
404 * c-basic-offset: 4
405 * End:
406 * vim600: sw=4 ts=4 fdm=marker
407 * vim<600: sw=4 ts=4
408 */
409
