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glibc  2.9
sigaltstack.c
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00001 /* Copyright (C) 1992, 93, 94, 95, 97, 98 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <hurd.h>
00021 #include <hurd/signal.h>
00022 
00023 /* Run signals handlers on the stack specified by SS (if not NULL).
00024    If OSS is not NULL, it is filled in with the old signal stack status.  */
00025 int
00026 __sigaltstack (argss, oss)
00027      const struct sigaltstack *argss;
00028      struct sigaltstack *oss;
00029 {
00030   struct hurd_sigstate *s;
00031   struct sigaltstack ss, old;
00032 
00033   /* Fault before taking any locks.  */
00034   if (argss != NULL)
00035     ss = *argss;
00036   if (oss != NULL)
00037     *(volatile struct sigaltstack *) oss = *oss;
00038 
00039   s = _hurd_self_sigstate ();
00040   __spin_lock (&s->lock);
00041 
00042   if (argss != NULL &&
00043       (ss.ss_flags & SS_DISABLE) && (s->sigaltstack.ss_flags & SS_ONSTACK))
00044     {
00045       /* Can't disable a stack that is in use.  */
00046       __spin_unlock (&s->lock);
00047       errno = EINVAL;
00048       return -1;
00049     }
00050 
00051   old = s->sigaltstack;
00052 
00053   if (argss != NULL)
00054     s->sigaltstack = ss;
00055 
00056   __spin_unlock (&s->lock);
00057 
00058   if (oss != NULL)
00059     *oss = old;
00060 
00061   return 0;
00062 }
00063 weak_alias (__sigaltstack, sigaltstack)