sysdeps/mach/hurd/sigaltstack.c

   1 /* Copyright (C) 1992, 1993, 1994, 1995 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <errno.h>
  21 #include <hurd.h>
  22 #include <hurd/signal.h>
  23
  24 /* Run signals handlers on the stack specified by SS (if not NULL).
  25    If OSS is not NULL, it is filled in with the old signal stack status.  */
  26 int
  27 DEFUN(sigaltstack, (ss, oss),
  28       CONST struct sigaltstack *argss AND 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 & SA_DISABLE) && (s->sigaltstack.ss_flags & SA_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 }