1 /*

     2  * Copyright (c) 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.lang.instrument.ClassFileTransformer;

    25 import java.lang.instrument.IllegalClassFormatException;

    26 import java.lang.instrument.Instrumentation;

    27 import java.security.ProtectionDomain;

    28 import java.util.HashMap;

    29 

    30 // This is a test utility class used to transform

    31 // specified classes via initial transformation (ClassFileLoadHook).

    32 // Names of classes to be transformed are supplied as arguments,

    33 // the phrase to be transformed is a hard-coded predefined

    34 // fairly unique phrase.

    35 

    36 public class TransformerAgent {

    37     private static String[] classesToTransform;

    38 

    39 

    40     private static void log(String msg) {

    41         System.out.println("TransformerAgent: " + msg);

    42     }

    43 

    44 

    45     // arguments are comma-separated list of classes to transform

    46     public static void premain(String agentArguments, Instrumentation instrumentation) {

    47         log("premain() is called, arguments = " + agentArguments);

    48         classesToTransform = agentArguments.split(",");

    49         instrumentation.addTransformer(new SimpleTransformer(), /*canRetransform=*/true);

    50     }

    51 

    52 

    53     public static void agentmain(String args, Instrumentation inst) throws Exception {

    54         log("agentmain() is called");

    55         premain(args, inst);

    56     }

    57 

    58 

    59     static class SimpleTransformer implements ClassFileTransformer {

    60        public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,

    61                             ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

    62 

    63             log("SimpleTransformer called for: " + name + "@" + incrCounter(name));

    64             if (!shouldTransform(name))

    65                 return null;

    66 

    67             log("transforming: class name = " + name);

    68             int nrOfReplacements = TransformUtil.replace(buffer, TransformUtil.BeforePattern,

    69                                                          TransformUtil.AfterPattern);

    70             log("replaced the string, nrOfReplacements = " + nrOfReplacements);

    71             return buffer;

    72         }

    73 

    74         // Check class name pattern, since test should only transform certain classes

    75         private static boolean shouldTransform(String name) {

    76             for (String match : classesToTransform) {

    77                 if (name.matches(match)) {

    78                     log("shouldTransform: match-found, match = " + match);

    79                     return true;

    80                 }

    81             }

    82 

    83             return false;

    84         }

    85     }

    86 

    87 

    88     static HashMap<String, Integer> counterMap = new HashMap<>();

    89 

    90     static Integer incrCounter(String className) {

    91         Integer i = counterMap.get(className);

    92         if (i == null) {

    93             i = new Integer(1);

    94         } else {

    95             i = new Integer(i.intValue() + 1);

    96         }

    97         counterMap.put(className, i);

    98         return i;

    99     }

   100 }