Creates or opens a named semaphore with the specified name.

Syntax

#include <pripcsem.h>

#define PR_SEM_CREATE 0x1 /* create if not exist */

#define PR_SEM_EXCL 0x2 /* fail if already exists */

NSPR_API(PRSem *) PR_OpenSemaphore(
  const char *name,
  PRIntn flags,
  PRIntn mode,
  PRUintn value
);

Parameters

The function has the following parameters:

name

The name to be given the semaphore.

flags

How to create or open the semaphore.

mode

Unix style file mode to be used when creating the semaphore.

value

The initial value assigned to the semaphore.

Returns

A pointer to a PRSem structure or NULL/code> on error.

Description

If the named semaphore doesn't exist and the PR_SEM_CREATE flag is specified, the named semaphore is created. The created semaphore needs to be removed from the system with a PR_DeleteSemaphore call.

If PR_SEM_CREATE is specified, the third argument is the access permission bits of the new semaphore (same interpretation as the mode argument to PR_Open) and the fourth argument is the initial value of the new semaphore. If PR_SEM_CREATE is not specified, the third and fourth arguments are ignored.