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.lang.instrument.Instrumentation; 25 import java.lang.instrument.ClassDefinition; 26 27 import jdk.internal.org.objectweb.asm.ClassWriter; 28 import jdk.internal.org.objectweb.asm.Label; 29 import jdk.internal.org.objectweb.asm.MethodVisitor; 30 import jdk.internal.org.objectweb.asm.Opcodes; 31 32 public class Agent implements Opcodes { 33 34 private static byte[] makeNewMartyr() { 35 ClassWriter cw = new ClassWriter(0); 36 MethodVisitor mv; 37 38 cw.visit(V1_8, ACC_PUBLIC + ACC_SUPER, "Martyr", null, "java/lang/Object", null); 39 cw.visitSource(null, null); 40 41 { 42 mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null); 43 mv.visitCode(); 44 Label lab0 = new Label(); 45 mv.visitLabel(lab0); 46 mv.visitLineNumber(1, lab0); 47 mv.visitVarInsn(ALOAD, 0); 48 mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V"); 49 mv.visitInsn(RETURN); 50 mv.visitMaxs(1, 1); 51 mv.visitEnd(); 52 } 53 54 { 55 mv = cw.visitMethod(ACC_PUBLIC, "getName", "()Ljava/lang/String;", null, null); 56 mv.visitCode(); 57 Label lab0 = new Label(); 58 mv.visitLabel(lab0); 59 mv.visitLineNumber(6, lab0); 60 mv.visitLdcInsn("Redefinition done"); 61 mv.visitInsn(ARETURN); 62 mv.visitMaxs(1, 1); 63 mv.visitEnd(); 64 } 65 66 { 67 mv = cw.visitMethod(ACC_PROTECTED, "finalize", "()V", null, null); 68 mv.visitCode(); 69 Label lab0 = new Label(); 70 mv.visitLabel(lab0); 71 mv.visitLineNumber(8, lab0); 72 mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"); 73 mv.visitLdcInsn("Finalizer called"); 74 mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V"); 75 mv.visitInsn(RETURN); 76 mv.visitMaxs(2, 1); 77 mv.visitEnd(); 78 } 79 80 cw.visitEnd(); 81 return cw.toByteArray(); 82 } 83 84 85 public static void premain(String args, Instrumentation inst) throws Exception { 86 agentmain(args, inst); 87 } 88 89 public static void agentmain(String args, Instrumentation inst) throws Exception { 90 ClassDefinition martyrDef = 91 new ClassDefinition(Class.forName("Martyr"), makeNewMartyr()); 92 inst.redefineClasses(martyrDef); 93 } 94 }