1 /*

     2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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

    21  * questions.

    22  */

    23 

    24 import java.io.PrintWriter;

    25 import java.lang.instrument.*;

    26 import com.oracle.java.testlibrary.*;

    27 

    28 /*

    29  * Helper class to write tests that redefine classes.

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

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

    32  *

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

    34  */

    35 public class RedefineClassHelper {

    36 

    37     public static Instrumentation instrumentation;

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

    39         instrumentation = inst;

    40     }

    41 

    42     /**

    43      * Redefine a class

    44      *

    45      * @param clazz Class to redefine

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

    47      */

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

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

    50         redefineClass(clazz, bytecode);

    51     }

    52 

    53     /**

    54      * Redefine a class

    55      *

    56      * @param clazz Class to redefine

    57      * @param bytecode byte[] with the new class

    58      */

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

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

    61     }

    62 

    63     /**

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

    65      */

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

    67         ClassFileInstaller.main("RedefineClassHelper");

    68 

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

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

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

    72         pw.close();

    73 

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

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

    76             throw new Exception("jar operation failed");

    77         }

    78     }

    79 }