1b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/* 2b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ProGuard -- shrinking, optimization, obfuscation, and preverification 3b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * of Java bytecode. 4b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 5b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) 6b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 7b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is free software; you can redistribute it and/or modify it 8b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * under the terms of the GNU General Public License as published by the Free 9b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Software Foundation; either version 2 of the License, or (at your option) 10b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * any later version. 11b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 12b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is distributed in the hope that it will be useful, but WITHOUT 13b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * more details. 16b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 17b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * You should have received a copy of the GNU General Public License along 18b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * with this program; if not, write to the Free Software Foundation, Inc., 19b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 21b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopackage proguard.obfuscate; 22b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 23b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.*; 24b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.*; 25b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.visitor.AttributeVisitor; 26b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.util.SimplifiedVisitor; 27b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.visitor.*; 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 29b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/** 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This ClassVisitor removes attributes that are not marked as being used or 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * required. 32b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 33b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @see AttributeUsageMarker 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @author Eric Lafortune 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopublic class AttributeShrinker 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoextends SimplifiedVisitor 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimplements ClassVisitor, 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato MemberVisitor, 41b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato AttributeVisitor 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato{ 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for ClassVisitor. 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitProgramClass(ProgramClass programClass) 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compact the array for class attributes. 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programClass.u2attributesCount = 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato shrinkArray(programClass.attributes, 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programClass.u2attributesCount); 51b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 52b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compact the attributes in fields, methods, and class attributes, 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programClass.fieldsAccept(this); 54b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programClass.methodsAccept(this); 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programClass.attributesAccept(this); 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitLibraryClass(LibraryClass libraryClass) 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Library classes are left unchanged. 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 63b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 64b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 65b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for MemberVisitor. 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitProgramMember(ProgramClass programClass, ProgramMember programMember) 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compact the attributes array. 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programMember.u2attributesCount = 71b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato shrinkArray(programMember.attributes, 72b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programMember.u2attributesCount); 73b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 74b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compact any attributes of the remaining attributes. 75b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato programMember.attributesAccept(programClass, this); 76b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 77b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 78b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 79b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for AttributeVisitor. 80b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 81b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} 82b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 83b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 84b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) 85b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 86b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compact the attributes array. 87b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttribute.u2attributesCount = 88b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato shrinkArray(codeAttribute.attributes, 89b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttribute.u2attributesCount); 90b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 91b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 92b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 93b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Small utility methods. 94b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 95b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 96b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Removes all VisitorAccepter objects that are not marked as being used 97b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * from the given array. 98b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @return the new number of VisitorAccepter objects. 99b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 100b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private static int shrinkArray(VisitorAccepter[] array, int length) 101b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 102b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato int counter = 0; 103b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 104b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Shift the used objects together. 105b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato for (int index = 0; index < length; index++) 106b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 107b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (AttributeUsageMarker.isUsed(array[index])) 108b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 109b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato array[counter++] = array[index]; 110b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 111b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 112b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 113b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Clear the remaining array elements. 114b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato for (int index = counter; index < length; index++) 115b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 116b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato array[index] = null; 117b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 118b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 119b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return counter; 120b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 121b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato} 122