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sem.h

/* Copyright (C) 1995, 1996, 1997, 1998
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

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

#ifndef _SYS_SEM_H
# error "Never include <bits/sem.h> directly; use <sys/sem.h> instead."
#endif

#include <sys/types.h>

/* Flags for `semop'.  */
#define SEM_UNDO  0x1000            /* undo the operation on exit */

/* Commands for `semctl'.  */
#define GETPID          11          /* get sempid */
#define GETVAL          12          /* get semval */
#define GETALL          13          /* get all semval's */
#define GETNCNT         14          /* get semncnt */
#define GETZCNT         15          /* get semzcnt */
#define SETVAL          16          /* set semval */
#define SETALL          17          /* set all semval's */


/* Data structure describing a set of semaphores.  */
struct semid_ds
{
  struct ipc_perm sem_perm;         /* operation permission struct */
  __time_t sem_otime;               /* last semop() time */
  __time_t sem_ctime;               /* last time changed by semctl() */
  unsigned short int sem_nsems;           /* number of semaphores in set */
};

/* The user should define a union like the following to use it for arguments
   for `semctl'.

   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
   };

   Previous versions of this file used to define this union but this is
   incorrect.  One can test the macro _SEM_SEMUN_UNDEFINED to see whether
   one must define the union or not.  */
#define _SEM_SEMUN_UNDEFINED  1

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