sysdeps/unix/sysv/linux/msgrcv.c

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