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.ASM7, 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 }