1/* 2 * ProGuard -- shrinking, optimization, obfuscation, and preverification 3 * of Java bytecode. 4 * 5 * Copyright (c) 2002-2014 Eric Lafortune (eric@graphics.cornell.edu) 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the Free 9 * Software Foundation; either version 2 of the License, or (at your option) 10 * any later version. 11 * 12 * This program is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 * more details. 16 * 17 * You should have received a copy of the GNU General Public License along 18 * with this program; if not, write to the Free Software Foundation, Inc., 19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21package proguard.obfuscate; 22 23import proguard.classfile.*; 24import proguard.classfile.attribute.*; 25import proguard.classfile.attribute.visitor.AttributeVisitor; 26import proguard.classfile.util.SimplifiedVisitor; 27 28/** 29 * This AttributeVisitor trims and marks all local variable (type) table 30 * attributes that it visits. It keeps parameter names and types and removes 31 * the ordinary local variable names and types. 32 * 33 * @author Eric Lafortune 34 */ 35public class ParameterNameMarker 36extends SimplifiedVisitor 37implements AttributeVisitor 38{ 39 private final AttributeVisitor attributeUsageMarker; 40 41 42 /** 43 * Constructs a new ParameterNameMarker. 44 * @param attributeUsageMarker the marker that will be used to mark 45 * attributes containing local variable info. 46 */ 47 public ParameterNameMarker(AttributeVisitor attributeUsageMarker) 48 { 49 this.attributeUsageMarker = attributeUsageMarker; 50 } 51 52 53 // Implementations for AttributeVisitor. 54 55 public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} 56 57 58 public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute) 59 { 60 if (!AttributeUsageMarker.isUsed(localVariableTableAttribute) && 61 hasParameters(clazz, method)) 62 { 63 // Shift the entries that start at offset 0 to the front. 64 int newIndex = 0; 65 66 for (int index = 0; index < localVariableTableAttribute.u2localVariableTableLength; index++) 67 { 68 LocalVariableInfo localVariableInfo = 69 localVariableTableAttribute.localVariableTable[index]; 70 71 if (localVariableInfo.u2startPC == 0) 72 { 73 localVariableTableAttribute.localVariableTable[newIndex++] = 74 localVariableInfo; 75 } 76 } 77 78 // Trim the table. 79 localVariableTableAttribute.u2localVariableTableLength = newIndex; 80 81 // Mark the table if there are any entries. 82 if (newIndex > 0) 83 { 84 attributeUsageMarker.visitLocalVariableTableAttribute(clazz, method, codeAttribute, localVariableTableAttribute); 85 } 86 } 87 } 88 89 90 public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute) 91 { 92 if (!AttributeUsageMarker.isUsed(localVariableTypeTableAttribute) && 93 hasParameters(clazz, method)) 94 { 95 // Shift the entries that start at offset 0 to the front. 96 int newIndex = 0; 97 98 for (int index = 0; index < localVariableTypeTableAttribute.u2localVariableTypeTableLength; index++) 99 { 100 LocalVariableTypeInfo localVariableTypeInfo = 101 localVariableTypeTableAttribute.localVariableTypeTable[index]; 102 103 if (localVariableTypeInfo.u2startPC == 0) 104 { 105 localVariableTypeTableAttribute.localVariableTypeTable[newIndex++] = 106 localVariableTypeInfo; 107 } 108 } 109 110 // Trim the table. 111 localVariableTypeTableAttribute.u2localVariableTypeTableLength = newIndex; 112 113 // Mark the table if there are any entries. 114 if (newIndex > 0) 115 { 116 attributeUsageMarker.visitLocalVariableTypeTableAttribute(clazz, method, codeAttribute, localVariableTypeTableAttribute); 117 } 118 } 119 } 120 121 122 // Small utility methods. 123 124 private boolean hasParameters(Clazz clazz, Method method) 125 { 126 return method.getDescriptor(clazz).charAt(1) != ClassConstants.METHOD_ARGUMENTS_CLOSE; 127 } 128}