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353 lines
10 KiB
C
353 lines
10 KiB
C
/*
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+----------------------------------------------------------------------+
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| PHP version 4.0 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997, 1998, 1999 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 2.0 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available at through the world-wide-web at |
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| http://www.php.net/license/2_0.txt. |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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| Authors: Tom May <tom@go2net.com> |
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+----------------------------------------------------------------------+
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*/
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/* $Id$ */
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/* This has been built and tested on Solaris 2.6 and Linux 2.1.122.
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* It may not compile or execute correctly on other systems.
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*
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* sas: Works for me on Linux 2.0.36 and FreeBSD 3.0-current
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*/
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#include "php.h"
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#if HAVE_SYSVSEM
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <errno.h>
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#include "php_sysvsem.h"
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#if !HAVE_SEMUN && defined(__GNU_LIBRARY__) && __GNU_LIBRARY__ == 6
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
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unsigned short int *array; /* array for GETALL, SETALL */
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struct seminfo *__buf; /* buffer for IPC_INFO */
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};
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#undef HAVE_SEMUN
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#define HAVE_SEMUN 1
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#endif
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function_entry sysvsem_functions[] = {
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{"sem_get", php3_sysvsem_get, NULL},
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{"sem_acquire", php3_sysvsem_acquire, NULL},
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{"sem_release", php3_sysvsem_release, NULL},
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{NULL, NULL, NULL}
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};
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zend_module_entry sysvsem_module_entry = {
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"System V semaphores", sysvsem_functions, php3_minit_sysvsem, NULL, NULL, NULL, NULL, STANDARD_MODULE_PROPERTIES
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};
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#if COMPILE_DL
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php3_module_entry *get_module() { return &sysvsem_module_entry; }
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#endif
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THREAD_LS sysvsem_module php3_sysvsem_module;
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/* Semaphore functions using System V semaphores. Each semaphore
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* actually consists of three semaphores allocated as a unit under the
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* same key. Semaphore 0 (SYSVSEM_SEM) is the actual semaphore, it is
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* initialized to max_acquire and decremented as processes acquire it.
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* The value of semaphore 1 (SYSVSEM_USAGE) is a count of the number
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* of processes using the semaphore. After calling semget(), if a
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* process finds that the usage count is 1, it will set the value of
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* SYSVSEM_SEM to max_acquire. This allows max_acquire to be set and
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* track the PHP code without having a global init routine or external
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* semaphore init code. Except see the bug regarding a race condition
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* php3_sysvsem_get(). Semaphore 2 (SYSVSEM_SETVAL) serializes the
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* calls to GETVAL SYSVSEM_USAGE and SETVAL SYSVSEM_SEM. It can be
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* acquired only when it is zero.
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*/
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#define SYSVSEM_SEM 0
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#define SYSVSEM_USAGE 1
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#define SYSVSEM_SETVAL 2
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static void release_sysvsem_sem(sysvsem_sem *sem_ptr)
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{
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struct sembuf sop[2];
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/* Decrement the usage count. */
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sop[0].sem_num = SYSVSEM_USAGE;
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sop[0].sem_op = -1;
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sop[0].sem_flg = SEM_UNDO;
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/* Release the semaphore if it has been acquired but not released. */
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if (sem_ptr->count) {
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php_error(E_WARNING, "Releasing SysV semaphore id %d key 0x%x in request cleanup", sem_ptr->id, sem_ptr->key);
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sop[1].sem_num = SYSVSEM_SEM;
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sop[1].sem_op = sem_ptr->count;
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sop[1].sem_flg = SEM_UNDO;
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}
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if (semop(sem_ptr->semid, sop, sem_ptr->count ? 2 : 1) == -1) {
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php_error(E_WARNING, "semop() failed in release_sysvsem_sem for key 0x%x: %s", sem_ptr->key, strerror(errno));
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}
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efree(sem_ptr);
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}
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int php3_minit_sysvsem(INIT_FUNC_ARGS)
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{
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php3_sysvsem_module.le_sem = register_list_destructors(release_sysvsem_sem, NULL);
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return SUCCESS;
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}
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#define SETVAL_WANTS_PTR
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#if defined(_AIX)
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#undef SETVAL_WANTS_PTR
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#endif
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/* {{{ proto int sem_get(int key [, int max_acquire [, int perm]])
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Return an id for the semaphore with the given key, and allow max_acquire (default 1) processes to acquire it simultaneously. */
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PHP_FUNCTION(sysvsem_get)
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{
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pval **arg_key, **arg_max_acquire, **arg_perm;
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int key, max_acquire, perm;
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int semid;
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struct sembuf sop[3];
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int count;
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sysvsem_sem *sem_ptr;
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#if HAVE_SEMUN
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union semun un;
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#endif
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max_acquire = 1;
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perm = 0666;
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switch (ARG_COUNT(ht)) {
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case 1:
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if (getParametersEx(1, &arg_key)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long_ex(arg_key);
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key = (int)(*arg_key)->value.lval;
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break;
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case 2:
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if (getParametersEx(2, &arg_key, &arg_max_acquire)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long_ex(arg_key);
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key = (int)(*arg_key)->value.lval;
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convert_to_long_ex(arg_max_acquire);
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max_acquire = (int)(*arg_max_acquire)->value.lval;
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break;
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case 3:
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if (getParametersEx(3, &arg_key, &arg_max_acquire, &arg_perm)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long_ex(arg_key);
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convert_to_long_ex(arg_max_acquire);
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convert_to_long_ex(arg_perm);
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key = (int)(*arg_key)->value.lval;
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max_acquire = (int)(*arg_max_acquire)->value.lval;
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perm = (int)(*arg_perm)->value.lval;
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break;
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default:
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WRONG_PARAM_COUNT;
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break;
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}
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/* Get/create the semaphore. Note that we rely on the semaphores
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* being zeroed when they are created. Despite the fact that
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* the(?) Linux semget() man page says they are not initialized,
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* the kernel versions 2.0.x and 2.1.z do in fact zero them.
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*/
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semid = semget(key, 3, perm|IPC_CREAT);
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if (semid == -1) {
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php_error(E_WARNING, "semget() failed for key 0x%x: %s", key, strerror(errno));
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RETURN_FALSE;
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}
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/* Find out how many processes are using this semaphore. Note
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* that on Linux (at least) there is a race condition here because
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* semaphore undo on process exit is not atomic, so we could
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* acquire SYSVSEM_SETVAL before a crashed process has decremented
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* SYSVSEM_USAGE in which case count will be greater than it
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* should be and we won't set max_acquire. Fortunately this
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* doesn't actually matter in practice.
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*/
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/* Wait for sem 1 to be zero . . . */
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sop[0].sem_num = SYSVSEM_SETVAL;
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sop[0].sem_op = 0;
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sop[0].sem_flg = 0;
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/* . . . and increment it so it becomes non-zero . . . */
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sop[1].sem_num = SYSVSEM_SETVAL;
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sop[1].sem_op = 1;
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sop[1].sem_flg = SEM_UNDO;
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/* . . . and increment the usage count. */
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sop[2].sem_num = SYSVSEM_USAGE;
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sop[2].sem_op = 1;
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sop[2].sem_flg = SEM_UNDO;
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while (semop(semid, sop, 3) == -1) {
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if (errno != EINTR) {
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php_error(E_WARNING, "semop() failed acquiring SYSVSEM_SETVAL for key 0x%x: %s", key, strerror(errno));
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break;
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}
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}
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/* Get the usage count. */
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#if HAVE_SEMUN
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count = semctl(semid, SYSVSEM_USAGE, GETVAL, un);
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#else
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count = semctl(semid, SYSVSEM_USAGE, GETVAL, NULL);
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#endif
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if (count == -1) {
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php_error(E_WARNING, "semctl(GETVAL) failed for key 0x%x: %s", key, strerror(errno));
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}
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/* If we are the only user, then take this opportunity to set the max. */
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if (count == 1) {
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#if HAVE_SEMUN
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/* This is correct for Linux which has union semun. */
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union semun semarg;
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semarg.val = max_acquire;
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if (semctl(semid, SYSVSEM_SEM, SETVAL, semarg) == -1) {
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php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
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}
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#elif defined(SETVAL_WANTS_PTR)
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/* This is correct for Solaris 2.6 which does not have union semun. */
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if (semctl(semid, SYSVSEM_SEM, SETVAL, &max_acquire) == -1) {
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php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
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}
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#else
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/* This works for i.e. AIX */
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if (semctl(semid, SYSVSEM_SEM, SETVAL, max_acquire) == -1) {
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php_error(E_WARNING, "semctl(SETVAL) failed for key 0x%x: %s", key, strerror(errno));
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}
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#endif
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}
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/* Set semaphore 1 back to zero. */
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sop[0].sem_num = SYSVSEM_SETVAL;
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sop[0].sem_op = -1;
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sop[0].sem_flg = SEM_UNDO;
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while (semop(semid, sop, 1) == -1) {
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if (errno != EINTR) {
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php_error(E_WARNING, "semop() failed releasing SYSVSEM_SETVAL for key 0x%x: %s", key, strerror(errno));
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break;
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}
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}
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sem_ptr = (sysvsem_sem *) emalloc(sizeof(sysvsem_sem));
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sem_ptr->key = key;
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sem_ptr->semid = semid;
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sem_ptr->count = 0;
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return_value->value.lval = php3_list_insert(sem_ptr, php3_sysvsem_module.le_sem);
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return_value->type = IS_LONG;
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sem_ptr->id = (int)return_value->value.lval;
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}
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/* }}} */
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static void _php3_sysvsem_semop(INTERNAL_FUNCTION_PARAMETERS, int acquire)
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{
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pval **arg_id;
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int id, type;
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sysvsem_sem *sem_ptr;
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struct sembuf sop;
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switch(ARG_COUNT(ht)) {
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case 1:
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if (getParametersEx(1, &arg_id)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long_ex(arg_id);
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id = (int)(*arg_id)->value.lval;
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break;
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default:
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WRONG_PARAM_COUNT;
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break;
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}
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sem_ptr = (sysvsem_sem *) php3_list_find(id, &type);
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if (type!=php3_sysvsem_module.le_sem) {
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php_error(E_WARNING, "%d is not a SysV semaphore index", id);
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RETURN_FALSE;
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}
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if (!acquire && sem_ptr->count == 0) {
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php_error(E_WARNING, "SysV semaphore index %d (key 0x%x) is not currently acquired", id, sem_ptr->key);
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RETURN_FALSE;
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}
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sop.sem_num = SYSVSEM_SEM;
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sop.sem_op = acquire ? -1 : 1;
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sop.sem_flg = SEM_UNDO;
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while (semop(sem_ptr->semid, &sop, 1) == -1) {
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if (errno != EINTR) {
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php_error(E_WARNING, "semop(%s) failed for key 0x%x: %s",
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acquire ? "acquire" : "release", sem_ptr->key, strerror(errno));
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RETURN_FALSE;
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}
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}
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sem_ptr->count -= acquire ? -1 : 1;
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RETURN_TRUE;
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}
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/* {{{ proto int sem_acquire(int id)
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Acquires the semaphore with the given id, blocking if necessary. */
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PHP_FUNCTION(sysvsem_acquire)
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{
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_php3_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
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}
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/* }}} */
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/* {{{ proto int sem_release(int id)
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Releases the semaphore with the given id. */
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PHP_FUNCTION(sysvsem_release)
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{
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_php3_sysvsem_semop(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
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}
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/* }}} */
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#endif /* HAVE_SYSVSEM */
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/*
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* Local variables:
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* tab-width: 4
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* c-basic-offset: 4
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* End:
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*/
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