sem_getvalue(3rt) [sunos man page]

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)

SEM_GETVALUE(3P)					     POSIX Programmer's Manual						  SEM_GETVALUE(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       sem_getvalue - get the value of a semaphore (REALTIME)

SYNOPSIS

       #include <semaphore.h>

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

DESCRIPTION

       The sem_getvalue() function shall update the location referenced by the sval argument to have the value of the semaphore referenced by  sem
       without 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 object to which sval points shall either be set to zero or to a negative number whose absolute value	represents
       the number of processes waiting for the semaphore at some unspecified time during the call.

RETURN VALUE

       Upon  successful  completion,  the  sem_getvalue()  function shall return a value of zero. Otherwise, it shall return a value of -1 and set
       errno to indicate the error.

ERRORS

       The sem_getvalue() function shall fail if:

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The sem_getvalue() function is part of the Semaphores option and need not be available on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       semctl(), semget(), semop(), sem_post(), sem_timedwait(), sem_trywait(), sem_wait(), the Base Definitions volume  of  IEEE Std 1003.1-2001,
       <semaphore.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							  SEM_GETVALUE(3P)