/* Emulate sigstack function using sigaltstack.

   Copyright (C) 1998-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.

   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 <signal.h>

#include <stddef.h>

#include <sys/syscall.h>

#ifdef __NR_sigaltstack

int

sigstack (struct sigstack *ss, struct sigstack *oss)

{

  stack_t sas;

  stack_t *sasp = NULL;

  stack_t osas;

  stack_t *osasp = oss == NULL ? NULL : &osa;;

  int result;

  if (ss != NULL)

    {

      /* We have to convert the information.  */

      sas.ss_sp = ss->ss_sp;

      sas.ss_flags = ss->ss_onstack ? SS_ONSTACK : 0;

      /* For the size of the stack we have no value we can pass to the

	 kernel.  This is why this function should not be used.  We simply

	 assume that all the memory down to address zero (in case the stack

	 grows down) is available.  */

      sas.ss_size = ss->ss_sp - NULL;

      sasp = &sas;

    }

  /* Call the kernel.  */

  result = __sigaltstack (sasp, osasp);

  /* Convert the result, if wanted and possible.  */

  if (result == 0 && oss != NULL)

    {

      oss->ss_sp = osas.ss_sp;

      oss->ss_onstack = (osas.ss_flags & SS_ONSTACK) != 0;

    }

  return result;

}

link_warning (sigstack, "the `sigstack' function is dangerous.  `sigaltstack' should be used instead.")

#else

# include <signal/sigstack.c>

#endif