Gets the value of a specified semaphore.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <semaphore.h>

      int sem_getvalue  (sem_t *sem, int *sval);

1 - Argument

 sem

    The semaphore for which a value is to be returned.

 sval

    The location to be updated with the value of the semaphore
    indicated by the sem argument.

2 - Description

    The sem_getvalue function updates a location referenced by the
    sval argument with the value of semaphore sem. The updated value
    represents an actual semaphore value that occurred during the
    call, but may not be the actual value of the semaphore at the
    time that the value is returned to the calling process.

    If the semaphore is locked, the value returned will either be
    zero or a negative number indicating the number of processes
    waiting for the semaphore at some time during the call.

3 - Return Values

    0                  Successful completion.
    -1                 Indicates an error. The function sets errno to
                       one of the following values:

                       o  EINVAL - The sem argument is not a valid
                          semaphore.

                       o  EVMSERR - OpenVMS specific nontranslatable
                          error code.