sysdeps/unix/sysv/linux/msgrcv.c

   1 /* Copyright (C) 1995-2015 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 /* Kludge to work around Linux' restriction of only up to five
  27    arguments to a system call.  */
  28 struct ipc_kludge
  29   {
  30     void *msgp;
  31     long int msgtyp;
  32   };
  33
  34
  35 ssize_t
  36 __libc_msgrcv (msqid, msgp, msgsz, msgtyp, msgflg)
  37      int msqid;
  38      void *msgp;
  39      size_t msgsz;
  40      long int msgtyp;
  41      int msgflg;
  42 {
  43   /* The problem here is that Linux' calling convention only allows up to
  44      fives parameters to a system call.  */
  45   struct ipc_kludge tmp;
  46
  47   tmp.msgp = msgp;
  48   tmp.msgtyp = msgtyp;
  49
  50   if (SINGLE_THREAD_P)
  51     return INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg, &tmp);
  52
  53   int oldtype = LIBC_CANCEL_ASYNC ();
  54
  55   ssize_t result = INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg,
  56                                    &tmp);
  57
  58    LIBC_CANCEL_RESET (oldtype);
  59
  60   return result;
  61 }
  62 weak_alias (__libc_msgrcv, msgrcv)