DosOpenEventSem

Syntax

rc = DosOpenEventSem( pszSemaphoreName, 
                      phevSemaphore );

Parameters

PSZ pszSemaphoreName (input)

This is a pointer to a null-terminated string containing the name of the semaphore to gain access to. If pszSemaphoreName equals NULL then the handle contained in phevSemaphore will be used.

PHEV phevSemaphore (input/output)

This is a pointer to the HEV containing the handle of the semaphore to be opened. If the semaphore is to be opened by name using pszSemaphoreName then the input value of phevSemaphore must be NULL or ERROR_INVALID_PARAMETER will be returned. On successful return of this function, phevSemaphore will point to a Event handle (HEV) containing the opened semaphore.

Returns

 APIRET rc

The following values can be returned

0	NO_ERROR	Semaphore opened successfully
6	ERROR_INVALID_HANDLE	Error, The value in phevSemaphore does not point to a valid semaphore
8	ERROR_NOT_ENOUGH_MEMORY	Error, The system memory limit has been exceeded
87	ERROR_INVALID_PARAMETER	Error, One or more parameters is not recognized, See parameters above
123	ERROR_INVALID_NAME	Error, The name pointed to by pszSemaphoreName has been rejected by the file system
187	ERROR_SEM_NOT_FOUND	Error, There is no semaphore with the name in pszSemaphoreName
291	ERROR_TOO_MANY_OPENS	Error, The usage count for the semaphore in question has exceeded the system limit of 65535

Include Info

#define INCL_DOSSEMAPHORES
#include <os2.h>

Usage Explanation

DosOpenEventSem gains access to a shared semaphore for the calling process. When access is granted to the calling process, DosOpenEventSem increments, by one (1), the usage count for the semaphore pointed to by phevSemaphore or named in pszSemaphoreName.

Sample Code

#define INCL_DOSSEMAPHORES
#include 

UCHAR SemName[15];
PHEV phevMySemaphore= NULL; /* pointer to my semaphore handle */

	/* a shared Event semaphore is successfully created in another process */
	/* its name happens to be \SEM32\MySem */

	strcpy(SemName,"\\SEM32\\MySem");

	rc = DosOpenEventSem(SemName, phevMySemaphore);

	if (rc != 0)
	{
	  /* We got an error to take care of. */
	}
	else
	{
	  /* The semaphore was successfully opened */
	  /* it may be accessed via the handle pointer, phevMySemaphore */
	}

See Also

DosCloseEventSem, DosCreateEventSem, DosPostEventSem DosQueryEventSem, DosResetEventSem DosWaitEventSem