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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sys/shm.h>
  21 #include <ipc_priv.h>
  22
  23 #include <sysdep.h>
  24 #include <unistd.h>
  25 #include <sys/syscall.h>
  26 #include <bp-checks.h>
  27
  28 /* Attach the shared memory segment associated with SHMID to the data
  29    segment of the calling process.  SHMADDR and SHMFLG determine how
  30    and where the segment is attached.  */
  31
  32 void *
  33 shmat (shmid, shmaddr, shmflg)
  34      int shmid;
  35      const void *shmaddr;
  36      int shmflg;
  37 {
  38   void *__unbounded result;
  39   void *__unbounded raddr;
  40
  41 #if __BOUNDED_POINTERS__
  42   size_t length = ~0;
  43   struct shmid_ds shmds;
  44   /* It's unfortunate that we need to make another system call to get
  45      the shared memory segment length...  */
  46   if (shmctl (shmid, IPC_STAT, &shmds) == 0)
  47     length = shmds.shm_segsz;
  48 #endif
  49
  50   result = (void *__unbounded) INLINE_SYSCALL (ipc, 5, IPCOP_shmat,
  51                                                shmid, shmflg,
  52                                                (long int) __ptrvalue (&raddr),
  53                                                __ptrvalue ((void *) shmaddr));
  54   if ((unsigned long) result <= -(unsigned long) SHMLBA)
  55     result = raddr;
  56
  57   return BOUNDED_N (result, length);
  58 }