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php-src/ext/sysvsem/sysvsem.c
Sebastian Bergmann 38933514e1 Update headers.
2001-12-11 15:32:16 +00:00

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/*
+----------------------------------------------------------------------+
| PHP Version 4 |
+----------------------------------------------------------------------+
| Copyright (c) 1997-2002 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 2.02 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available at through the world-wide-web at |
| http://www.php.net/license/2_02.txt. |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Tom May <tom@go2net.com> |
| Gavin Sherry <gavin@linuxworld.com.au> |
+----------------------------------------------------------------------+
*/
/* $Id$ */
/* Latest update build anc tested on Linux 2.2.14
*
* This has been built and tested on Solaris 2.6 and Linux 2.1.122.
* It may not compile or execute correctly on other systems.
*
* sas: Works for me on Linux 2.0.36 and FreeBSD 3.0-current
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "php.h"
#if HAVE_SYSVSEM
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#include "php_sysvsem.h"
#if !HAVE_SEMUN
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short int *array; /* array for GETALL, SETALL */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#undef HAVE_SEMUN
#define HAVE_SEMUN 1
#endif
/* {{{ sysvsem_functions[]
*/
function_entry sysvsem_functions[] = {
PHP_FE(sem_get, NULL)
PHP_FE(sem_acquire, NULL)
PHP_FE(sem_release, NULL)
PHP_FE(sem_remove, NULL)
{NULL, NULL, NULL}
};
/* }}} */
/* {{{ sysvsem_module_entry
*/
zend_module_entry sysvsem_module_entry = {
STANDARD_MODULE_HEADER,
"sysvsem", sysvsem_functions, PHP_MINIT(sysvsem), NULL, NULL, NULL, NULL, NO_VERSION_YET, STANDARD_MODULE_PROPERTIES
};
/* }}} */
#ifdef COMPILE_DL_SYSVSEM
ZEND_GET_MODULE(sysvsem)
#endif
THREAD_LS sysvsem_module php_sysvsem_module;
/* Semaphore functions using System V semaphores. Each semaphore
* actually consists of three semaphores allocated as a unit under the
* same key. Semaphore 0 (SYSVSEM_SEM) is the actual semaphore, it is
* initialized to max_acquire and decremented as processes acquire it.
* The value of semaphore 1 (SYSVSEM_USAGE) is a count of the number
* of processes using the semaphore. After calling semget(), if a
* process finds that the usage count is 1, it will set the value of
* SYSVSEM_SEM to max_acquire. This allows max_acquire to be set and
* track the PHP code without having a global init routine or external
* semaphore init code. Except see the bug regarding a race condition
* php_sysvsem_get(). Semaphore 2 (SYSVSEM_SETVAL) serializes the
* calls to GETVAL SYSVSEM_USAGE and SETVAL SYSVSEM_SEM. It can be
* acquired only when it is zero.
*/
#define SYSVSEM_SEM 0
#define SYSVSEM_USAGE 1
#define SYSVSEM_SETVAL 2
/* {{{ release_sysvsem_sem
*/
static void release_sysvsem_sem(zend_rsrc_list_entry *rsrc TSRMLS_DC)
{
sysvsem_sem *sem_ptr = (sysvsem_sem *)rsrc->ptr;
struct sembuf sop[2];
/*
* if count == -1, semaphore has been removed
* Need better way to handle this
*/
if(sem_ptr->count == -1) {
return;
}
/* Decrement the usage count. */
sop[0].sem_num = SYSVSEM_USAGE;
sop[0].sem_op = -1;
sop[0].sem_flg = SEM_UNDO;
/* Release the semaphore if it has been acquired but not released. */
if (sem_ptr->count) {
php_error(E_WARNING, "Releasing SysV semaphore id %d key 0x%x in request cleanup", sem_ptr->id, sem_ptr->key);
sop[1].sem_num = SYSVSEM_SEM;
sop[1].sem_op = sem_ptr->count;
sop[1].sem_flg = SEM_UNDO;
}
if (semop(sem_ptr->semid, sop, sem_ptr->count ? 2 : 1) == -1) {
php_error(E_WARNING, "semop() failed in release_sysvsem_sem for key 0x%x: %s", sem_ptr->key, strerror(errno));
}
efree(sem_ptr);
}
/* }}} */
/* {{{ PHP_MINIT_FUNCTION
*/
PHP_MINIT_FUNCTION(sysvsem)
{
php_sysvsem_module.le_sem = zend_register_list_destructors_ex(release_sysvsem_sem, NULL, "sysvsem", module_number);
return SUCCESS;
}
/* }}} */
#define SETVAL_WANTS_PTR
#if defined(_AIX)
#undef SETVAL_WANTS_PTR
#endif
/* {{{ proto int sem_get(int key [, int max_acquire [, int perm]])
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)
{
pval **arg_key, **arg_max_acquire, **arg_perm;
int key, max_acquire, perm;
int semid;
struct sembuf sop[3];
int count;
sysvsem_sem *sem_ptr;
#if HAVE_SEMUN
union semun un;
#endif
max_acquire = 1;
perm = 0666;
switch (ZEND_NUM_ARGS()) {
case 1:
if (zend_get_parameters_ex(1, &arg_key)==FAILURE) {
RETURN_FALSE;
}
convert_to_long_ex(arg_key);
key = (int)Z_LVAL_PP(arg_key);
break;
case 2:
if (zend_get_parameters_ex(2, &arg_key, &arg_max_acquire)==FAILURE) {
RETURN_FALSE;
}
convert_to_long_ex(arg_key);
key = (int)Z_LVAL_PP(arg_key);
convert_to_long_ex(arg_max_acquire);
max_acquire = (int)Z_LVAL_PP(arg_max_acquire);
break;
case 3:
if (zend_get_parameters_ex(3, &arg_key, &arg_max_acquire, &arg_perm)==FAILURE) {
RETURN_FALSE;
}
convert_to_long_ex(arg_key);
convert_to_long_ex(arg_max_acquire);
convert_to_long_ex(arg_perm);
key = (int)Z_LVAL_PP(arg_key);
max_acquire = (int)Z_LVAL_PP(arg_max_acquire);
perm = (int)Z_LVAL_PP(arg_perm);
break;
default:
WRONG_PARAM_COUNT;
break;
}
/* Get/create the semaphore. Note that we rely on the semaphores
* being zeroed when they are created. Despite the fact that
* the(?) Linux semget() man page says they are not initialized,
* the kernel versions 2.0.x and 2.1.z do in fact zero them.
*/
semid = semget(key, 3, perm|IPC_CREAT);
if (semid == -1) {
php_error(E_WARNING, "semget() failed for key 0x%x: %s", key, strerror(errno));
RETURN_FALSE;
}
/* Find out how many processes are using this semaphore. Note
* that on Linux (at least) there is a race condition here because
* semaphore undo on process exit is not atomic, so we could
* acquire SYSVSEM_SETVAL before a crashed process has decremented
* SYSVSEM_USAGE in which case count will be greater than it
* should be and we won't set max_acquire. Fortunately this
* doesn't actually matter in practice.
*/
/* Wait for sem 1 to be zero . . . */
sop[0].sem_num = SYSVSEM_SETVAL;
sop[0].sem_op = 0;
sop[0].sem_flg = 0;
/* . . . and increment it so it becomes non-zero . . . */
sop[1].sem_num = SYSVSEM_SETVAL;
sop[1].sem_op = 1;
sop[1].sem_flg = SEM_UNDO;
/* . . . and increment the usage count. */
sop[2].sem_num = SYSVSEM_USAGE;
sop[2].sem_op = 1;
sop[2].sem_flg = SEM_UNDO;
while (semop(semid, sop, 3) == -1) {
if (errno != EINTR) {
php_error(E_WARNING, "semop() failed acquiring SYSVSEM_SETVAL for key 0x%x: %s", key, strerror(errno));
break;
}
}
/* Get the usage count. */
#if HAVE_SEMUN
count = semctl(semid, SYSVSEM_USAGE, GETVAL, un);
#else
count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
#endif
if (count == -1) {
php_error(E_WARNING, "semctl(GETVAL) failed for key 0x%x: %s", key, strerror(errno));
}
/* If we are the only user, then take this opportunity to set the max. */
if (count == 1) {
#if HAVE_SEMUN
/* This is correct for Linux which has union semun. */
union semun semarg;
semarg.val = max_acquire;
if (semctl(semid, SYSVSEM_SEM, SETVAL, semarg) == -1) {
php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
}
#elif defined(SETVAL_WANTS_PTR)
/* This is correct for Solaris 2.6 which does not have union semun. */
if (semctl(semid, SYSVSEM_SEM, SETVAL, &max_acquire) == -1) {
php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
}
#else
/* This works for i.e. AIX */
if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
}
#endif
}
/* Set semaphore 1 back to zero. */
sop[0].sem_num = SYSVSEM_SETVAL;
sop[0].sem_op = -1;
sop[0].sem_flg = SEM_UNDO;
while (semop(semid, sop, 1) == -1) {
if (errno != EINTR) {
php_error(E_WARNING, "semop() failed releasing SYSVSEM_SETVAL for key 0x%x: %s", key, strerror(errno));
break;
}
}
sem_ptr = (sysvsem_sem *) emalloc(sizeof(sysvsem_sem));
sem_ptr->key = key;
sem_ptr->semid = semid;
sem_ptr->count = 0;
Z_LVAL_P(return_value) = zend_list_insert(sem_ptr, php_sysvsem_module.le_sem);
Z_TYPE_P(return_value) = IS_LONG;
sem_ptr->id = (int)Z_LVAL_P(return_value);
}
/* }}} */
/* {{{ php_sysvsem_semop
*/
static void php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
{
pval **arg_id;
int id, type;
sysvsem_sem *sem_ptr;
struct sembuf sop;
switch(ZEND_NUM_ARGS()) {
case 1:
if (zend_get_parameters_ex(1, &arg_id)==FAILURE) {
RETURN_FALSE;
}
convert_to_long_ex(arg_id);
id = (int)Z_LVAL_PP(arg_id);
break;
default:
WRONG_PARAM_COUNT;
break;
}
sem_ptr = (sysvsem_sem *) zend_list_find(id, &type);
if (type!=php_sysvsem_module.le_sem) {
php_error(E_WARNING, "%d is not a SysV semaphore index", id);
RETURN_FALSE;
}
if (!acquire && sem_ptr->count == 0) {
php_error(E_WARNING, "SysV semaphore index %d (key 0x%x) is not currently acquired", id, sem_ptr->key);
RETURN_FALSE;
}
sop.sem_num = SYSVSEM_SEM;
sop.sem_op = acquire ? -1 : 1;
sop.sem_flg = SEM_UNDO;
while (semop(sem_ptr->semid, &sop, 1) == -1) {
if (errno != EINTR) {
php_error(E_WARNING, "semop(%s) failed for key 0x%x: %s",
acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
RETURN_FALSE;
}
}
sem_ptr->count -= acquire ? -1 : 1;
RETURN_TRUE;
}
/* }}} */
/* {{{ proto int sem_acquire(int id)
Acquires the semaphore with the given id, blocking if necessary */
PHP_FUNCTION(sem_acquire)
{
php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
}
/* }}} */
/* {{{ proto int sem_release(int id)
Releases the semaphore with the given id */
PHP_FUNCTION(sem_release)
{
php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
}
/* }}} */
/* {{{ proto int sem_remove(int id)
Removes semaphore from Unix systems */
/*
* contributed by Gavin Sherry gavin@linuxworld.com.au
* Fri Mar 16 00:50:13 EST 2001
*/
PHP_FUNCTION(sem_remove)
{
pval **arg_id;
int id,type;
sysvsem_sem *sem_ptr;
#if HAVE_SEMUN
union semun un;
#endif
if(ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &arg_id) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_long_ex(arg_id);
id = Z_LVAL_PP(arg_id);
sem_ptr = (sysvsem_sem *) zend_list_find(id, &type);
if (type!=php_sysvsem_module.le_sem) {
php_error(E_WARNING, "%d is not a SysV semaphore index", id);
RETURN_FALSE;
}
#if HAVE_SEMUN
if(semctl(sem_ptr->semid,NULL,IPC_STAT,un)<0) {
#else
if(semctl(sem_ptr->semid,NULL,IPC_STAT,NULL)<0) {
#endif
php_error(E_WARNING, "%d is not a existing SysV Semaphore Id", id);
RETURN_FALSE;
}
if(semctl(sem_ptr->semid,NULL,IPC_RMID,NULL)<0) {
php_error(E_WARNING, "sem_remove() failed for id %d: %s", id, strerror(errno));
RETURN_FALSE;
}
/* let release_sysvsem_sem know we have removed
* the semaphore to avoid issues with releasing.
*/
sem_ptr->count = -1;
RETURN_TRUE;
}
/* }}} */
#endif /* HAVE_SYSVSEM */
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* End:
* vim600: sw=4 ts=4 fdm=marker
* vim<600: sw=4 ts=4
*/
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