001: /*
002: * ProGuard -- shrinking, optimization, obfuscation, and preverification
003: * of Java bytecode.
004: *
005: * Copyright (c) 2002-2007 Eric Lafortune (eric@graphics.cornell.edu)
006: *
007: * This program is free software; you can redistribute it and/or modify it
008: * under the terms of the GNU General Public License as published by the Free
009: * Software Foundation; either version 2 of the License, or (at your option)
010: * any later version.
011: *
012: * This program is distributed in the hope that it will be useful, but WITHOUT
013: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
014: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
015: * more details.
016: *
017: * You should have received a copy of the GNU General Public License along
018: * with this program; if not, write to the Free Software Foundation, Inc.,
019: * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020: */
021: package proguard.obfuscate;
022:
023: import proguard.classfile.*;
024: import proguard.classfile.util.*;
025: import proguard.classfile.visitor.MemberVisitor;
026:
027: import java.util.*;
028:
029: /**
030: * This MemberVisitor obfuscates all class members that it visits.
031: * It uses names from the given name factory. At the same time, it avoids names
032: * from the given descriptor map.
033: * <p>
034: * The class members must have been linked before applying this visitor.
035: *
036: * @see MethodLinker
037: *
038: * @author Eric Lafortune
039: */
040: public class MemberObfuscator extends SimplifiedVisitor implements
041: MemberVisitor {
042: private final boolean allowAggressiveOverloading;
043: private final NameFactory nameFactory;
044: private final Map descriptorMap;
045:
046: /**
047: * Creates a new MemberObfuscator.
048: * @param allowAggressiveOverloading a flag that specifies whether class
049: * members can be overloaded aggressively.
050: * @param nameFactory the factory that can produce
051: * obfuscated member names.
052: * @param descriptorMap the map of descriptors to
053: * [new name - old name] maps.
054: */
055: public MemberObfuscator(boolean allowAggressiveOverloading,
056: NameFactory nameFactory, Map descriptorMap) {
057: this .allowAggressiveOverloading = allowAggressiveOverloading;
058: this .nameFactory = nameFactory;
059: this .descriptorMap = descriptorMap;
060: }
061:
062: // Implementations for MemberVisitor.
063:
064: public void visitAnyMember(Clazz clazz, Member member) {
065: // Special cases: <clinit> and <init> are always kept unchanged.
066: // We can ignore them here.
067: String name = member.getName(clazz);
068: if (name.equals(ClassConstants.INTERNAL_METHOD_NAME_CLINIT)
069: || name
070: .equals(ClassConstants.INTERNAL_METHOD_NAME_INIT)) {
071: return;
072: }
073:
074: // Get the member's descriptor.
075: String descriptor = member.getDescriptor(clazz);
076:
077: // Check whether we're allowed to do aggressive overloading
078: if (!allowAggressiveOverloading) {
079: // Trim the return argument from the descriptor if not.
080: // Works for fields and methods alike.
081: descriptor = descriptor.substring(0, descriptor
082: .indexOf(')') + 1);
083: }
084:
085: // Get the name map, creating a new one if necessary.
086: Map nameMap = retrieveNameMap(descriptorMap, descriptor);
087:
088: // Get the member's new name.
089: String newName = newMemberName(member);
090:
091: // Assign a new one, if necessary.
092: if (newName == null) {
093: // Find an acceptable new name.
094: nameFactory.reset();
095:
096: do {
097: newName = nameFactory.nextName();
098: } while (nameMap.containsKey(newName));
099:
100: // Remember not to use the new name again in this name space.
101: nameMap.put(newName, name);
102:
103: // Assign the new name.
104: setNewMemberName(member, newName);
105: }
106: }
107:
108: // Small utility methods.
109:
110: /**
111: * Gets the name map, based on the given map and a given descriptor.
112: * A new empty map is created if necessary.
113: * @param descriptorMap the map of descriptors to [new name - old name] maps.
114: * @param descriptor the class member descriptor.
115: * @return the corresponding name map.
116: */
117: static Map retrieveNameMap(Map descriptorMap, String descriptor) {
118: // See if we can find the nested map with this descriptor key.
119: Map nameMap = (Map) descriptorMap.get(descriptor);
120:
121: // Create a new one if not.
122: if (nameMap == null) {
123: nameMap = new HashMap();
124: descriptorMap.put(descriptor, nameMap);
125: }
126:
127: return nameMap;
128: }
129:
130: /**
131: * Assigns a fixed new name to the given class member.
132: * @param member the class member.
133: * @param name the new name.
134: */
135: static void setFixedNewMemberName(Member member, String name) {
136: VisitorAccepter lastVisitorAccepter = MethodLinker
137: .lastVisitorAccepter(member);
138:
139: if (!(lastVisitorAccepter instanceof LibraryMember)
140: && !(lastVisitorAccepter instanceof MyFixedName)) {
141: lastVisitorAccepter.setVisitorInfo(new MyFixedName(name));
142: } else {
143: lastVisitorAccepter.setVisitorInfo(name);
144: }
145: }
146:
147: /**
148: * Assigns a new name to the given class member.
149: * @param member the class member.
150: * @param name the new name.
151: */
152: static void setNewMemberName(Member member, String name) {
153: MethodLinker.lastVisitorAccepter(member).setVisitorInfo(name);
154: }
155:
156: /**
157: * Returns whether the new name of the given class member is fixed.
158: * @param member the class member.
159: * @return whether its new name is fixed.
160: */
161: static boolean hasFixedNewMemberName(Member member) {
162: VisitorAccepter lastVisitorAccepter = MethodLinker
163: .lastVisitorAccepter(member);
164:
165: return lastVisitorAccepter instanceof LibraryMember
166: || lastVisitorAccepter instanceof MyFixedName;
167: }
168:
169: /**
170: * Retrieves the new name of the given class member.
171: * @param member the class member.
172: * @return the class member's new name, or <code>null</code> if it doesn't
173: * have one yet.
174: */
175: static String newMemberName(Member member) {
176: return (String) MethodLinker.lastVisitorAccepter(member)
177: .getVisitorInfo();
178: }
179:
180: /**
181: * This VisitorAccepter can be used to wrap a name string, to indicate that
182: * the name is fixed.
183: */
184: private static class MyFixedName implements VisitorAccepter {
185: private String newName;
186:
187: public MyFixedName(String newName) {
188: this .newName = newName;
189: }
190:
191: // Implementations for VisitorAccepter.
192:
193: public Object getVisitorInfo() {
194: return newName;
195: }
196:
197: public void setVisitorInfo(Object visitorInfo) {
198: newName = (String) visitorInfo;
199: }
200: }
201: }
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