1 /* 2 * Copyright (c) 2012, 2018, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.jfr.internal.instrument; 27 28 import java.io.ByteArrayInputStream; 29 import java.io.IOException; 30 import java.io.InputStream; 31 32 import jdk.internal.org.objectweb.asm.ClassReader; 33 import jdk.internal.org.objectweb.asm.ClassVisitor; 34 import jdk.internal.org.objectweb.asm.ClassWriter; 35 import jdk.internal.org.objectweb.asm.MethodVisitor; 36 import jdk.internal.org.objectweb.asm.Opcodes; 37 import jdk.internal.org.objectweb.asm.Type; 38 39 final class ConstructorTracerWriter extends ClassVisitor { 40 41 private ConstructorWriter useInputParameter, noUseInputParameter; 42 43 static byte[] generateBytes(Class<?> clz, byte[] oldBytes) throws IOException { 44 InputStream in = new ByteArrayInputStream(oldBytes); 45 ClassReader cr = new ClassReader(in); 46 ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS); 47 ConstructorTracerWriter ctw = new ConstructorTracerWriter(cw, clz); 48 cr.accept(ctw, 0); 49 return cw.toByteArray(); 50 } 51 52 private ConstructorTracerWriter(ClassVisitor cv, Class<?> classToChange) { 53 super(Opcodes.ASM5, cv); 54 useInputParameter = new ConstructorWriter(classToChange, true); 55 noUseInputParameter = new ConstructorWriter(classToChange, false); 56 } 57 58 private boolean isConstructor(String name) { 59 return name.equals("<init>"); 60 } 61 62 private boolean takesStringParameter(String desc) { 63 Type[] types = Type.getArgumentTypes(desc); 64 if (types.length > 0 && types[0].getClassName().equals(String.class.getName())) { 65 return true; 66 } 67 return false; 68 } 69 70 @Override 71 public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) { 72 73 MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions); 74 75 // Get a hold of the constructors that takes a String as a parameter 76 if (isConstructor(name)) { 77 if (takesStringParameter(desc)) { 78 useInputParameter.setMethodVisitor(mv); 79 return useInputParameter; 80 } 81 noUseInputParameter.setMethodVisitor(mv); 82 return noUseInputParameter; 83 } 84 return mv; 85 } 86 }