1 /*
   2  * Copyright (c) 2014, 2017, 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 
  25 import java.lang.instrument.ClassFileTransformer;
  26 import java.lang.instrument.IllegalClassFormatException;
  27 import java.security.ProtectionDomain;
  28 
  29 // Note: Util is from /test/hotspot/jtreg/runtime/appcds/test-classes/TestCommon.java
  30 
  31 public class InstrumentationClassFileTransformer implements ClassFileTransformer {
  32     public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
  33                             ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
  34 
  35         if (name.startsWith("InstrumentationApp$") && !name.equals("InstrumentationApp$NotTransformed")) {
  36             System.out.println("Transforming: " + name + " class = " + classBeingRedefined);
  37             try {
  38                 if (classBeingRedefined == null) {
  39                     // Initial transform
  40                     replace(buffer, "buzz", "fuzz");
  41                 } else {
  42                     replace(buffer, "buzz", "guzz"); // Retransform
  43                     replace(buffer, "huzz", "quzz"); // Redefine
  44                 }
  45             } catch (Throwable t) {
  46                 t.printStackTrace();
  47             }
  48             return buffer;
  49         }
  50         return null;
  51     }
  52 
  53     static void replace(byte[] buffer, String from, String to) {
  54         int n = Util.replace(buffer, from, to);
  55         System.out.println("..... replaced " + n + " occurrence(s) of '" + from + "' to '" + to + "'");
  56     }
  57 }