Standard C Library Functions                     semgetvalue(3C)



NAME
     semgetvalue - get the value of a semaphore

SYNOPSIS
     #include 

     int semgetvalue(semt *restrict sem, int *restrict sval);


DESCRIPTION
     The semgetvalue() function updates the location  referenced
     by  the  sval  argument  to  have the value of the semaphore
     referenced by sem without affecting the state of  the  sema-
     phore.  The  updated  value  represents  an actual semaphore
     value that occurred at  some  unspecified  time  during  the
     call,  but  it need not be the actual value of the semaphore
     when it is returned to the calling process.


     If sem is locked, then the value returned by  semgetvalue()
     is  either  zero  or  a negative number whose absolute value
     represents the number of processes waiting for the semaphore
     at some unspecified time during the call.


     The value set in sval may be 0 or positive. If  sval  is  0,
     there  may  be  other processes (or LWPs or threads) waiting
     for the semaphore; if sval is positive, no process is  wait-
     ing.

RETURN VALUES
     Upon successful completion, semgetvalue() returns 0. Other-
     wise, it returns -1 and sets errno to indicate the error.

ERORS
     The  semgetvalue() function will fail if:

     EINVAL     The sem argument does not refer to a valid  sema-
                phore.


     ENOSYS     The semgetvalue() function is not  supported  by
                the system.


ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:







SunOS 5.11           Last change: 5 Feb 2008                    1






Standard C Library Functions                     semgetvalue(3C)



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Committed                   
    
     MT-Level                     MT-Safe                     
    
     Standard                     See standards(5).           
    


SEE ALSO
     semctl(2), semget(2), semop(2), sempost(3C),  semwait(3C),
     attributes(5), standards(5)









































SunOS 5.11           Last change: 5 Feb 2008                    2