Opens an existing shared memory segment or, if one with the specified name doesn't exist, creates a new one.
Syntax
#include <prshm.h>
NSPR_API( PRSharedMemory * )
PR_OpenSharedMemory(
const char *name,
PRSize size,
PRIntn flags,
PRIntn mode
);
/* Define values for PR_OpenShareMemory(...,create) */
#define PR_SHM_CREATE 0x1 /* create if not exist */
#define PR_SHM_EXCL 0x2 /* fail if already exists */
Parameters
The function has the following parameters:
- name
- The name of the shared memory segment.
- size
- The size of the shared memory segment.
- flags
- Options for creating the shared memory.
- mode
- Same as passed to
PR_Open.
Returns
Pointer to opaque structure PRSharedMemory, or NULL if an error occurs. Retrieve the reason for the failure by calling PR_GetError and PR_GetOSError.
Description
PR_OpenSharedMemory creates a new shared memory segment or associates a previously created memory segment with the specified name. When parameter create is (PR_SHM_EXCL | PR_SHM_CREATE) and the shared memory already exists, the function returns NULL with the error set to PR_FILE_EXISTS_ERROR.
When parameter create is PR_SHM_CREATE and the shared memory already exists, a handle to that memory segment is returned. If the segment does not exist, it is created and a pointer to the related PRSharedMemory structure is returned.
When parameter create is 0, and the shared memory exists, a pointer to a PRSharedMemory structure is returned. If the shared memory does not exist, NULL is returned with the error set to PR_FILE_NOT_FOUND_ERROR.