/*

 * Copyright (c) 2008, Oracle and/or its affiliates. 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.

 *

 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.InputStream;

import java.lang.instrument.ClassDefinition;

import java.lang.instrument.Instrumentation;

import java.util.Timer;

import java.util.TimerTask;

public class RedefineClassWithNativeMethodAgent {

    static Class clz;

    // just read the original class and redefine it via a Timer

    public static void premain(String agentArgs, final Instrumentation inst) throws Exception {

        String s = agentArgs.substring(0, agentArgs.indexOf(".class"));

        clz = Class.forName(s.replace('/', '.'));

        InputStream in;

        Module m = clz.getModule();

        if (m != null) {

            in = m.getResourceAsStream(agentArgs);

        } else {

            ClassLoader loader =

                RedefineClassWithNativeMethodAgent.class.getClassLoader();

            in = loader.getResourceAsStream(agentArgs);

        }

        if (in == null) {

            throw new Exception("Cannot find class: " + agentArgs);

        }

        byte[] buffer = in.readAllBytes();

        new Timer(true).schedule(new TimerTask() {

            public void run() {

                try {

                    System.out.println("Instrumenting");

                    ClassDefinition cld = new ClassDefinition(clz, buffer);

                    inst.redefineClasses(new ClassDefinition[] { cld });

                }

                catch (Exception e) { e.printStackTrace(); }

            }

        }, 500);

    }

}