/*
 * Copyright 1999-2001 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package java.lang;

import sun.misc.Signal;
import sun.misc.SignalHandler;


/**
 * Package-private utility class for setting up and tearing down
 * platform-specific support for termination-triggered shutdowns.
 *
 * @author   Mark Reinhold
 * @since    1.3
 */

class Terminator {

    private static SignalHandler handler = null;

    /* Invocations of setup and teardown are already synchronized
     * on the shutdown lock, so no further synchronization is needed here
     */

    static void setup() {
        if (handler != null) return;
        SignalHandler sh = new SignalHandler() {
            public void handle(Signal sig) {
                Shutdown.exit(sig.getNumber() + 0200);
            }
        };
        handler = sh;
        try {
            Signal.handle(new Signal("HUP"), sh);
            Signal.handle(new Signal("INT"), sh);
            Signal.handle(new Signal("TERM"), sh);
        } catch (IllegalArgumentException e) {
            // When -Xrs is specified the user is responsible for
            // ensuring that shutdown hooks are run by calling
            // System.exit()
        }
    }

    static void teardown() {
        /* The current sun.misc.Signal class does not support
         * the cancellation of handlers
         */
    }

}