1 /*
   2  * Copyright (c) 2014, 2016, 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 jdk.test.lib.compiler.InMemoryJavaCompiler;
  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 }