PR_WaitSemaphore
================
Returns the value of the environment variable.
Syntax
------
.. code::
#include <pripcsem.h>
NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
Parameter
~~~~~~~~~
The function has the following parameter:
``sem``
A pointer to a ``PRSem`` structure returned from a call to
:ref:`PR_OpenSemaphore`.
Returns
~~~~~~~
:ref:`PRStatus`
Description
-----------
:ref:`PR_WaitSemaphore` tests the value of the semaphore. If the value of
the semaphore is > 0, the value of the semaphore is decremented and the
function returns. If the value of the semaphore is 0, the function
blocks until the value becomes > 0, then the semaphore is decremented
and the function returns.
The "test and decrement" operation is performed atomically.
