/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include "lint.h"
#include <sys/types.h>
#include <sys/ucontext.h>
#include <signal.h>
#include <errno.h>

int
sigstack(struct sigstack *nss, struct sigstack *oss)
{
	struct sigaltstack nalt;
	struct sigaltstack oalt;
	struct sigaltstack *naltp;

	if (nss) {
		/* Assumes stack growth is down */
		nalt.ss_sp = (char *)nss->ss_sp - SIGSTKSZ;
		nalt.ss_size = SIGSTKSZ;
		nalt.ss_flags = 0;
		naltp = &nalt;
	} else
		naltp = (struct sigaltstack *)0;

	if (sigaltstack(naltp, &oalt) < 0)
		return (-1);

	if (oss) {
		/* Assumes stack growth is down */
		oss->ss_sp = (char *)oalt.ss_sp + oalt.ss_size;
		oss->ss_onstack = ((oalt.ss_flags & SS_ONSTACK) != 0);
	}
	return (0);
}