bits/sem.h

   1 /* Copyright (C) 1995, 1996, 1997, 1998
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _SYS_SEM_H
  20 # error "Never include <bits/sem.h> directly; use <sys/sem.h> instead."
  21 #endif
  22
  23 #include <sys/types.h>
  24
  25 /* Flags for `semop'.  */
  26 #define SEM_UNDO        0x1000          /* undo the operation on exit */
  27
  28 /* Commands for `semctl'.  */
  29 #define GETPID          11              /* get sempid */
  30 #define GETVAL          12              /* get semval */
  31 #define GETALL          13              /* get all semval's */
  32 #define GETNCNT         14              /* get semncnt */
  33 #define GETZCNT         15              /* get semzcnt */
  34 #define SETVAL          16              /* set semval */
  35 #define SETALL          17              /* set all semval's */
  36
  37
  38 /* Data structure describing a set of semaphores.  */
  39 struct semid_ds
  40 {
  41   struct ipc_perm sem_perm;             /* operation permission struct */
  42   __time_t sem_otime;                   /* last semop() time */
  43   __time_t sem_ctime;                   /* last time changed by semctl() */
  44   unsigned short int sem_nsems;         /* number of semaphores in set */
  45 };
  46
  47 /* The user should define a union like the following to use it for arguments
  48    for `semctl'.
  49
  50    union semun
  51    {
  52      int val;                           <= value for SETVAL
  53      struct semid_ds *buf;              <= buffer for IPC_STAT & IPC_SET
  54      unsigned short int *array;         <= array for GETALL & SETALL
  55      struct seminfo *__buf;             <= buffer for IPC_INFO
  56    };
  57
  58    Previous versions of this file used to define this union but this is
  59    incorrect.  One can test the macro _SEM_SEMUN_UNDEFINED to see whether
  60    one must define the union or not.  */
  61 #define _SEM_SEMUN_UNDEFINED    1