/* Copyright (C) 1992-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <hurd.h>

#include <hurd/signal.h>

/* Run signals handlers on the stack specified by SS (if not NULL).

   If OSS is not NULL, it is filled in with the old signal stack status.  */

int

__sigaltstack (const stack_t *argss, stack_t *oss)

{

  struct hurd_sigstate *s;

  stack_t ss, old;

  /* Fault before taking any locks.  */

  if (argss != NULL)

    ss = *argss;

  if (oss != NULL)

    *(volatile stack_t *) oss = *oss;

  s = _hurd_self_sigstate ();

  __spin_lock (&s->lock);

  if (argss != NULL &&

      (ss.ss_flags & SS_DISABLE) && (s->sigaltstack.ss_flags & SS_ONSTACK))

    {

      /* Can't disable a stack that is in use.  */

      __spin_unlock (&s->lock);

      errno = EINVAL;

      return -1;

    }

  old = s->sigaltstack;

  if (argss != NULL)

    s->sigaltstack = ss;

  __spin_unlock (&s->lock);

  if (oss != NULL)

    *oss = old;

  return 0;

}

libc_hidden_def (__sigaltstack)

weak_alias (__sigaltstack, sigaltstack)