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glibc  2.9
msgrcv.c
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00001 /* Copyright (C) 1995,1997,1998,2000,2002,2006 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include <sys/msg.h>
00022 #include <ipc_priv.h>
00023 
00024 #include <sysdep-cancel.h>
00025 #include <sys/syscall.h>
00026 
00027 #include <bp-checks.h>
00028 
00029 /* Kludge to work around Linux' restriction of only up to five
00030    arguments to a system call.  */
00031 struct ipc_kludge
00032   {
00033     void *__unbounded msgp;
00034     long int msgtyp;
00035   };
00036 
00037 
00038 ssize_t
00039 __libc_msgrcv (msqid, msgp, msgsz, msgtyp, msgflg)
00040      int msqid;
00041      void *msgp;
00042      size_t msgsz;
00043      long int msgtyp;
00044      int msgflg;
00045 {
00046   /* The problem here is that Linux' calling convention only allows up to
00047      fives parameters to a system call.  */
00048   struct ipc_kludge tmp;
00049 
00050   tmp.msgp = CHECK_N (msgp, msgsz);
00051   tmp.msgtyp = msgtyp;
00052 
00053   if (SINGLE_THREAD_P)
00054     return INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg,
00055                         __ptrvalue (&tmp));
00056 
00057   int oldtype = LIBC_CANCEL_ASYNC ();
00058 
00059   ssize_t result = INLINE_SYSCALL (ipc, 5, IPCOP_msgrcv, msqid, msgsz, msgflg,
00060                                __ptrvalue (&tmp));
00061 
00062    LIBC_CANCEL_RESET (oldtype);
00063 
00064   return result;
00065 }
00066 weak_alias (__libc_msgrcv, msgrcv)