/*

 * Copyright (c) 2014, 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.PrintWriter;

import java.lang.instrument.*;

import com.oracle.java.testlibrary.*;

/*

 * Helper class to write tests that redefine classes.

 * When main method is run, it will create a redefineagent.jar that can be used

 * with the -javaagent option to support redefining classes in jtreg tests.

 *

 * See sample test in test/testlibrary_tests/RedefineClassTest.java

 */

public class RedefineClassHelper {

    public static Instrumentation instrumentation;

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

        instrumentation = inst;

    }

    /**

     * Redefine a class

     *

     * @param clazz Class to redefine

     * @param javacode String with the new java code for the class to be redefined

     */

    public static void redefineClass(Class clazz, String javacode) throws Exception {

        byte[] bytecode = InMemoryJavaCompiler.compile(clazz.getName(), javacode);

        redefineClass(clazz, bytecode);

    }

    /**

     * Redefine a class

     *

     * @param clazz Class to redefine

     * @param bytecode byte[] with the new class

     */

    public static void redefineClass(Class clazz, byte[] bytecode) throws Exception {

        instrumentation.redefineClasses(new ClassDefinition(clazz, bytecode));

    }

    /**

     * Main method to be invoked before test to create the redefineagent.jar

     */

    public static void main(String[] args) throws Exception {

        ClassFileInstaller.main("RedefineClassHelper");

        PrintWriter pw = new PrintWriter("MANIFEST.MF");

        pw.println("Premain-Class: RedefineClassHelper");

        pw.println("Can-Redefine-Classes: true");

        pw.close();

        sun.tools.jar.Main jarTool = new sun.tools.jar.Main(System.out, System.err, "jar");

        if (!jarTool.run(new String[] { "-cmf", "MANIFEST.MF", "redefineagent.jar", "RedefineClassHelper.class" })) {

            throw new Exception("jar operation failed");

        }

    }

}