sem_getvalue(3) [osf1 man page]

sem_getvalue(3) 					     Library Functions Manual						   sem_getvalue(3)

NAME

       sem_getvalue - Gets the value of a specified semaphore (P1003.1b)

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <semaphore.h>

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

PARAMETERS

       sem	 Specifies a pointer to the semaphore for which a value is to be returned.

       sval	 References a location to be updated with the value of the semaphore indicated by the sem argument.

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.

RETURN VALUES

       On a successful call, a value of 0 (zero) is returned. Otherwise, a value of -1 is returned and errno is set  to  indicate  that  an  error
       occurred.

ERRORS

       The  sem_getvalue function fails under the following condition:

       [EINVAL]       The sem argument does not refer to a valid semaphore.

RELATED INFORMATION

       Functions: sem_post(3), sem_trywait(3), sem_wait(3)

       Guide to Realtime Programming delim off

																   sem_getvalue(3)

sem_getvalue(3RT)					    Realtime Library Functions						 sem_getvalue(3RT)

NAME

       sem_getvalue - get the value of a semaphore

SYNOPSIS

       cc [ flag... ] file... -lrt [ library... ]
       #include <semaphore.h>

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

DESCRIPTION

       The sem_getvalue() function updates the location referenced by the sval argument to have the value of the semaphore referenced by sem with-
       out affecting the state of the semaphore. 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 sem_getvalue() 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 waiting.

RETURN VALUES

       Upon successful completion, sem_getvalue() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

ERRORS

       The  sem_getvalue() function will fail if:

       EINVAL	       The sem argument does not refer to a valid semaphore.

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

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       semctl(2), semget(2), semop(2), sem_post(3RT), sem_wait(3RT), attributes(5), standards(5)

SunOS 5.10							    1 Nov 2003							 sem_getvalue(3RT)