Description:
------------
The actual php version is 

# php --version
PHP 5.5.0-dev (cli) (built: Aug 24 2012 16:34:36) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies

php was configured with:
./configure --enable-sysvsem --enable-sysvshm --enable-pcntl

sem_acquire won't lock when a forked process acquires the semaphore. This 
behaviour is the same whether sem_get is called in every process or before the 
first pcntl_fork. 

It would seem sem_acquire treats forked processes as if they where the same 
process as the father, even if the got different pid.

I also tryed this bug with 

$ php --version
PHP 5.3.10-1ubuntu3.2 with Suhosin-Patch (cli) (built: Jun 13 2012 17:19:58) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies

in 

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.1 LTS
Release:        12.04
Codename:       precise

whith exactly the same results. Thanks.

Test script:
---------------
<?php
$pid = pcntl_fork();
if ($pid == -1) {
	die("could not fork 1");
} else if ($pid) {
	$pid = pcntl_fork();
	if ($pid == -1) {
		die("could not fork 2");
	} else if($pid) {
		$sem = sem_get('1234');
		echo "father try acquire $sem\n";
		$time = microtime();
		sem_acquire($sem);
		echo "father acquired in ".($time-microtime())."\n";
	} else {
		$sem = sem_get('1234');
		echo "son 2 try acquire $sem\n";
		$time=microtime();
		sem_acquire($sem);
		echo "son 2 acquired in ".($time-microtime())."\n";
	}
} else {
	$sem = sem_get('1234');
	echo "son 1 try acquire $sem\n";
	$time=microtime();
	sem_acquire($sem);
	echo "son 1 acquired in ".($time-microtime())."\n";
}
?>

Expected result:
----------------
storage-tests:~ # php prueba.php 
father try acquire Resource id #4                                                                                            
father acquired in -4.6999999999964E-5                                                                                       
son 2 try acquire Resource id #4                                                                                             
son 1 try acquire Resource id #4

Actual result:
--------------
storage-tests:~ # php prueba.php 
father try acquire Resource id #4                                                                                            
father acquired in -4.6999999999964E-5                                                                                       
son 2 try acquire Resource id #4                                                                                             
son 1 try acquire Resource id #4                                                                                             
son 2 acquired in -0.00010599999999999                                                                                       
son 1 acquired in -0.00010499999999997