sysdeps/mach/hurd/sigaltstack.c

   1 /* Copyright (C) 1992-2016 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <hurd.h>
  20 #include <hurd/signal.h>
  21
  22 /* Run signals handlers on the stack specified by SS (if not NULL).
  23    If OSS is not NULL, it is filled in with the old signal stack status.  */
  24 int
  25 __sigaltstack (const struct sigaltstack *argss, struct sigaltstack *oss)
  26 {
  27   struct hurd_sigstate *s;
  28   struct sigaltstack ss, old;
  29
  30   /* Fault before taking any locks.  */
  31   if (argss != NULL)
  32     ss = *argss;
  33   if (oss != NULL)
  34     *(volatile struct sigaltstack *) oss = *oss;
  35
  36   s = _hurd_self_sigstate ();
  37   __spin_lock (&s->lock);
  38
  39   if (argss != NULL &&
  40       (ss.ss_flags & SS_DISABLE) && (s->sigaltstack.ss_flags & SS_ONSTACK))
  41     {
  42       /* Can't disable a stack that is in use.  */
  43       __spin_unlock (&s->lock);
  44       errno = EINVAL;
  45       return -1;
  46     }
  47
  48   old = s->sigaltstack;
  49
  50   if (argss != NULL)
  51     s->sigaltstack = ss;
  52
  53   __spin_unlock (&s->lock);
  54
  55   if (oss != NULL)
  56     *oss = old;
  57
  58   return 0;
  59 }
  60 weak_alias (__sigaltstack, sigaltstack)