sysdeps/unix/sysv/linux/shmat.c

   1 /* Copyright (C) 1995,1997,1998,1999,2000,2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <sys/shm.h>
  22 #include <ipc_priv.h>
  23
  24 #include <sysdep.h>
  25 #include <unistd.h>
  26 #include <sys/syscall.h>
  27 #include <bp-checks.h>
  28
  29 /* Attach the shared memory segment associated with SHMID to the data
  30    segment of the calling process.  SHMADDR and SHMFLG determine how
  31    and where the segment is attached.  */
  32
  33 void *
  34 shmat (shmid, shmaddr, shmflg)
  35      int shmid;
  36      const void *shmaddr;
  37      int shmflg;
  38 {
  39   void *__unbounded result;
  40   void *__unbounded raddr;
  41
  42 #if __BOUNDED_POINTERS__
  43   size_t length = ~0;
  44   struct shmid_ds shmds;
  45   /* It's unfortunate that we need to make another system call to get
  46      the shared memory segment length...  */
  47   if (shmctl (shmid, IPC_STAT, &shmds) == 0)
  48     length = shmds.shm_segsz;
  49 #endif
  50
  51   result = (void *__unbounded) INLINE_SYSCALL (ipc, 5, IPCOP_shmat,
  52                                                shmid, shmflg,
  53                                                (long int) __ptrvalue (&raddr),
  54                                                __ptrvalue ((void *) shmaddr));
  55   if ((unsigned long) result <= -(unsigned long) SHMLBA)
  56     result = raddr;
  57
  58   return BOUNDED_N (result, length);
  59 }