glibc/sysdeps/unix/sysv/linux/semctl.c

/* Copyright (C) 1995, 1997, 1998 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <stdarg.h>
#include <sys/sem.h>

#include <sysdep.h>
#include <sys/syscall.h>

/* Define a `union semun' suitable for Linux here.  */
union semun
{
  int val;			/* value for SETVAL */
  struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */
  unsigned short int *array;	/* array for GETALL & SETALL */
  struct seminfo *__buf;	/* buffer for IPC_INFO */
};


/* Return identifier for array of NSEMS semaphores associated with
   KEY.  */

int
semctl (int semid, int semnum, int cmd, ...)
{
  union semun *arg;
  va_list ap;

  va_start (ap, cmd);

  /* Get a pointer the argument.  */
  arg = &va_arg (ap, union semun);

  va_end (ap);

  return INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd, arg);
}