bits/sem.h

   1 /* Copyright (C) 1995-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _SYS_SEM_H
  19 # error "Never include <bits/sem.h> directly; use <sys/sem.h> instead."
  20 #endif
  21
  22 #include <sys/types.h>
  23
  24 /* Flags for `semop'.  */
  25 #define SEM_UNDO        0x1000          /* undo the operation on exit */
  26
  27 /* Commands for `semctl'.  */
  28 #define GETPID          11              /* get sempid */
  29 #define GETVAL          12              /* get semval */
  30 #define GETALL          13              /* get all semval's */
  31 #define GETNCNT         14              /* get semncnt */
  32 #define GETZCNT         15              /* get semzcnt */
  33 #define SETVAL          16              /* set semval */
  34 #define SETALL          17              /* set all semval's */
  35
  36
  37 /* Data structure describing a set of semaphores.  */
  38 struct semid_ds
  39 {
  40   struct ipc_perm sem_perm;             /* operation permission struct */
  41   __time_t sem_otime;                   /* last semop() time */
  42   __time_t sem_ctime;                   /* last time changed by semctl() */
  43   unsigned short int sem_nsems;         /* number of semaphores in set */
  44 };
  45
  46 /* The user should define a union like the following to use it for arguments
  47    for `semctl'.
  48
  49    union semun
  50    {
  51      int val;                           <= value for SETVAL
  52      struct semid_ds *buf;              <= buffer for IPC_STAT & IPC_SET
  53      unsigned short int *array;         <= array for GETALL & SETALL
  54      struct seminfo *__buf;             <= buffer for IPC_INFO
  55    };
  56
  57    Previous versions of this file used to define this union but this is
  58    incorrect.  One can test the macro _SEM_SEMUN_UNDEFINED to see whether
  59    one must define the union or not.  */
  60 #define _SEM_SEMUN_UNDEFINED    1