sysdeps/unix/sysv/linux/msgrcv.c

   1 /* Copyright (C) 1995,1997,1998,2000,2002,2006 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/msg.h>
  21 #include <ipc_priv.h>
  22
  23 #include <sysdep-cancel.h>
  24 #include <sys/syscall.h>
  25
  26 #include <bp-checks.h>
  27
  28 /* Kludge to work around Linux' restriction of only up to five
  29    arguments to a system call.  */
  30 struct ipc_kludge
  31   {
  32     void *__unbounded msgp;
  33     long int msgtyp;
  34   };
  35
  36
  37 ssize_t
  38 __libc_msgrcv (msqid, msgp, msgsz, msgtyp, msgflg)
  39      int msqid;
  40      void *msgp;
  41      size_t msgsz;
  42      long int msgtyp;
  43      int msgflg;
  44 {
  45   /* The problem here is that Linux' calling convention only allows up to
  46      fives parameters to a system call.  */
  47   struct ipc_kludge tmp;
  48
  49   tmp.msgp = CHECK_N (msgp, msgsz);
  50   tmp.msgtyp = msgtyp;
  51
  52   if (SINGLE_THREAD_P)
  53     return INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg,
  54                            __ptrvalue (&tmp));
  55
  56   int oldtype = LIBC_CANCEL_ASYNC ();
  57
  58   ssize_t result = INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg,
  59                                    __ptrvalue (&tmp));
  60
  61    LIBC_CANCEL_RESET (oldtype);
  62
  63   return result;
  64 }
  65 weak_alias (__libc_msgrcv, msgrcv)