/*
+----------------------------------------------------------------------+
| PHP Version 5 |
+----------------------------------------------------------------------+
| Copyright (c) 1997-2014 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 3.01 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.php.net/license/3_01.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: sysvsem.c,v 1.1.1.4 2014/06/15 20:04:00 misho Exp $ */
/* 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
/* {{{ arginfo */
ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_get, 0, 0, 1)
ZEND_ARG_INFO(0, key)
ZEND_ARG_INFO(0, max_acquire)
ZEND_ARG_INFO(0, perm)
ZEND_ARG_INFO(0, auto_release)
ZEND_END_ARG_INFO()
ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_acquire, 0, 0, 1)
ZEND_ARG_INFO(0, sem_identifier)
ZEND_END_ARG_INFO()
ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_release, 0, 0, 1)
ZEND_ARG_INFO(0, sem_identifier)
ZEND_END_ARG_INFO()
ZEND_BEGIN_ARG_INFO_EX(arginfo_sem_remove, 0, 0, 1)
ZEND_ARG_INFO(0, sem_identifier)
ZEND_END_ARG_INFO()
/* }}} */
/* {{{ sysvsem_functions[]
*/
const zend_function_entry sysvsem_functions[] = {
PHP_FE(sem_get, arginfo_sem_get)
PHP_FE(sem_acquire, arginfo_sem_acquire)
PHP_FE(sem_release, arginfo_sem_release)
PHP_FE(sem_remove, arginfo_sem_remove)
PHP_FE_END
};
/* }}} */
/* {{{ 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];
int opcount = 1;
/*
* if count == -1, semaphore has been removed
* Need better way to handle this
*/
if (sem_ptr->count == -1 || !sem_ptr->auto_release) {
efree(sem_ptr);
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) {
sop[1].sem_num = SYSVSEM_SEM;
sop[1].sem_op = sem_ptr->count;
sop[1].sem_flg = SEM_UNDO;
opcount++;
}
semop(sem_ptr->semid, sop, opcount);
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 resource sem_get(int key [, int max_acquire [, int perm [, int auto_release]])
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)
{
long key, max_acquire = 1, perm = 0666, auto_release = 1;
int semid;
struct sembuf sop[3];
int count;
sysvsem_sem *sem_ptr;
if (FAILURE == zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l|lll", &key, &max_acquire, &perm, &auto_release)) {
RETURN_FALSE;
}
/* 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_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %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_docref(NULL TSRMLS_CC, E_WARNING, "failed acquiring SYSVSEM_SETVAL for key 0x%lx: %s", key, strerror(errno));
break;
}
}
/* Get the usage count. */
count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
if (count == -1) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %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_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %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_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %s", key, strerror(errno));
}
#else
/* This works for i.e. AIX */
if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for key 0x%lx: %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_docref(NULL TSRMLS_CC, E_WARNING, "failed releasing SYSVSEM_SETVAL for key 0x%lx: %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;
sem_ptr->auto_release = auto_release;
sem_ptr->id = ZEND_REGISTER_RESOURCE(return_value, sem_ptr, php_sysvsem_module.le_sem);
}
/* }}} */
/* {{{ php_sysvsem_semop
*/
static void php_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
{
zval *arg_id;
sysvsem_sem *sem_ptr;
struct sembuf sop;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "r", &arg_id) == FAILURE) {
return;
}
ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, &arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
if (!acquire && sem_ptr->count == 0) {
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);
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_docref(NULL TSRMLS_CC, E_WARNING, "failed to %s key 0x%x: %s", acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
RETURN_FALSE;
}
}
sem_ptr->count -= acquire ? -1 : 1;
RETURN_TRUE;
}
/* }}} */
/* {{{ proto bool sem_acquire(resource id)
Acquires the semaphore with the given id, blocking if necessary */
PHP_FUNCTION(sem_acquire)
{
php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
}
/* }}} */
/* {{{ proto bool sem_release(resource id)
Releases the semaphore with the given id */
PHP_FUNCTION(sem_release)
{
php_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
}
/* }}} */
/* {{{ proto bool sem_remove(resource 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)
{
zval *arg_id;
sysvsem_sem *sem_ptr;
#if HAVE_SEMUN
union semun un;
struct semid_ds buf;
#endif
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "r", &arg_id) == FAILURE) {
return;
}
ZEND_FETCH_RESOURCE(sem_ptr, sysvsem_sem *, &arg_id, -1, "SysV semaphore", php_sysvsem_module.le_sem);
#if HAVE_SEMUN
un.buf = &buf;
if (semctl(sem_ptr->semid, 0, IPC_STAT, un) < 0) {
#else
if (semctl(sem_ptr->semid, 0, IPC_STAT, NULL) < 0) {
#endif
php_error_docref(NULL TSRMLS_CC, E_WARNING, "SysV semaphore %ld does not (any longer) exist", Z_LVAL_P(arg_id));
RETURN_FALSE;
}
#if HAVE_SEMUN
if (semctl(sem_ptr->semid, 0, IPC_RMID, un) < 0) {
#else
if (semctl(sem_ptr->semid, 0, IPC_RMID, NULL) < 0) {
#endif
php_error_docref(NULL TSRMLS_CC, E_WARNING, "failed for SysV sempphore %ld: %s", Z_LVAL_P(arg_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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