sysdeps/mach/hurd/sigaltstack.c

   1 /* Copyright (C) 1992, 93, 94, 95, 97, 98 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <hurd.h>
  21 #include <hurd/signal.h>
  22
  23 /* Run signals handlers on the stack specified by SS (if not NULL).
  24    If OSS is not NULL, it is filled in with the old signal stack status.  */
  25 int
  26 __sigaltstack (argss, oss)
  27      const struct sigaltstack *argss;
  28      struct sigaltstack *oss;
  29 {
  30   struct hurd_sigstate *s;
  31   struct sigaltstack ss, old;
  32
  33   /* Fault before taking any locks.  */
  34   if (argss != NULL)
  35     ss = *argss;
  36   if (oss != NULL)
  37     *(volatile struct sigaltstack *) oss = *oss;
  38
  39   s = _hurd_self_sigstate ();
  40   __spin_lock (&s->lock);
  41
  42   if (argss != NULL &&
  43       (ss.ss_flags & SS_DISABLE) && (s->sigaltstack.ss_flags & SS_ONSTACK))
  44     {
  45       /* Can't disable a stack that is in use.  */
  46       __spin_unlock (&s->lock);
  47       errno = EINVAL;
  48       return -1;
  49     }
  50
  51   old = s->sigaltstack;
  52
  53   if (argss != NULL)
  54     s->sigaltstack = ss;
  55
  56   __spin_unlock (&s->lock);
  57
  58   if (oss != NULL)
  59     *oss = old;
  60
  61   return 0;
  62 }
  63 weak_alias (__sigaltstack, sigaltstack)