DosQueryMuxWaitSem
DosQueryMuxWaitSem returns the semaphore records of the MuxWait semaphore referred to by hmuxSemaphore.
Syntax
rc = DosQueryMuxWaitSem( hmuxSemaphore,
pulSemaphoreRecords,
pSemaphoreRecord,
pflAttributes );
Parameters
- HMUX hmuxSemaphore (input)
- The handle of the MuxWait semaphore to be queried.
- PULONG pulSemaphoreRecords (input/output)
- For input, this points to a ULONG that contains the number of SEMRECORDs that may be returned in the SEMRECORD structure pointed to by
pSemaphoreRecord.
- If this value is not enough to contain all SEMRECORDs from the MuxWait list then ERROR_PARAM_TOO_SMALL is returned and this value points to the number of records in the MuxWait list. For output, this value points to the number of SEMRECORDs actually returned.
- PSEMRECORD pSemaphoreRecord (output)
- A pointer to a buffer that will get the SEMRECORDs.
- PULONG pflAttributes (output)
- The attribute flags that were specified when this MuxWait semaphore was created.
- DC_SEM_SHARED indicates the semaphore is shared.
- DCMW_WAIT_ANY indicates the semaphore will unblock if any of the semaphores in the MuxWait list either post or release.
- DCMW_WAIT_ALL indicates the semaphore will unblock only if all of the semaphores in the MuxWait list either post or release.
Returns
- APIRET rc
- The following values can be returned
- 0: NO_ERROR - Operation successful
- 6: ERROR_INVALID_HANDLE - Error, The value in phmuxSemaphore 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, Both pszSemaphoreName and phmuxSemaphore may be NULL
- 105: ERROR_SEM_OWNER_DIED - Error, The owner of the semaphore has died without freeing the semaphore
- 289: ERROR_PARAM_TOO_SMALL - Error, The value pointed to by pulSemaphoreRecords is too small
Gotchas
The process calling DosQueryMuxWaitSem must first obtain access to the semaphore in question or ERROR_INVALID_HANDLE will be returned.
Sample Code
#define INCL_DOSSEMAPHORES
#include <os2.h>
HMUX hmuxMySemaphore; /* my semaphore handle */
ULONG ulNumSemRecords=1; /* will get the request count for the sem */
SEMRECORD SemRecord; /* single SEMRECORD structure */
PULONG pflAttribs; /* pointer to attribute flags */
/* access is gained to the semaphore in question
either by DosCreateMuxWaitSem or by DosOpenMuxWaitSem
its handle is placed in hmuxMySemaphore */
rc = DosQueryMuxWaitSem( hmuxMySemaphore,
ulNumSemRecords,
&SemRecord,
&pflAttribs );
if (rc != 0)
{
/* We got an error to take care of. */
}