bits/shm.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_SHM_H
  19 # error "Never include <bits/shm.h> directly; use <sys/shm.h> instead."
  20 #endif
  21
  22 #include <bits/types.h>
  23
  24 /* Flags for `shmat'.  */
  25 #define SHM_RDONLY      010000          /* attach read-only else read-write */
  26 #define SHM_RND         020000          /* round attach address to SHMLBA */
  27 #define SHM_REMAP       040000          /* take-over region on attach */
  28
  29 /* Commands for `shmctl'.  */
  30 #define SHM_LOCK        11              /* lock segment (root only) */
  31 #define SHM_UNLOCK      12              /* unlock segment (root only) */
  32
  33 __BEGIN_DECLS
  34
  35 /* Segment low boundary address multiple.  */
  36 #define SHMLBA          (__getpagesize ())
  37 extern int __getpagesize (void) __THROW __attribute__ ((__const__));
  38
  39
  40 /* Type to count number of attaches.  */
  41 typedef unsigned short int shmatt_t;
  42
  43 /* Data structure describing a shared memory segment.  */
  44 struct shmid_ds
  45   {
  46     struct ipc_perm shm_perm;           /* operation permission struct */
  47     size_t shm_segsz;                   /* size of segment in bytes */
  48     __time_t shm_atime;                 /* time of last shmat() */
  49     __time_t shm_dtime;                 /* time of last shmdt() */
  50     __time_t shm_ctime;                 /* time of last change by shmctl() */
  51     __pid_t shm_cpid;                   /* pid of creator */
  52     __pid_t shm_lpid;                   /* pid of last shmop */
  53     shmatt_t shm_nattch;                /* number of current attaches */
  54   };
  55
  56 __END_DECLS