1 package org.apache.bcel.verifier.structurals;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import org.apache.bcel.generic.Type;
58 import org.apache.bcel.generic.ReferenceType;
59 import org.apache.bcel.verifier.exc.*;
60
61 /***
62 * This class implements an array of local variables used for symbolic JVM
63 * simulation.
64 *
65 * @version $Id: LocalVariables.java,v 1.2 2002/08/02 11:57:51 enver Exp $
66 * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
67 */
68 public class LocalVariables{
69 /*** The Type[] containing the local variable slots. */
70 private Type[] locals;
71
72 /***
73 * Creates a new LocalVariables object.
74 */
75 public LocalVariables(int maxLocals){
76 locals = new Type[maxLocals];
77 for (int i=0; i<maxLocals; i++){
78 locals[i] = Type.UNKNOWN;
79 }
80 }
81
82 /***
83 * Returns a deep copy of this object; i.e. the clone
84 * operates on a new local variable array.
85 * However, the Type objects in the array are shared.
86 */
87 protected Object clone(){
88 LocalVariables lvs = new LocalVariables(locals.length);
89 for (int i=0; i<locals.length; i++){
90 lvs.locals[i] = this.locals[i];
91 }
92 return lvs;
93 }
94
95 /***
96 * Returns the type of the local variable slot i.
97 */
98 public Type get(int i){
99 return locals[i];
100 }
101
102 /***
103 * Returns a (correctly typed) clone of this object.
104 * This is equivalent to ((LocalVariables) this.clone()).
105 */
106 public LocalVariables getClone(){
107 return (LocalVariables) this.clone();
108 }
109
110 /***
111 * Returns the number of local variable slots this
112 * LocalVariables instance has.
113 */
114 public int maxLocals(){
115 return locals.length;
116 }
117
118 /***
119 * Sets a new Type for the given local variable slot.
120 */
121 public void set(int i, Type type){
122 if (type == Type.BYTE || type == Type.SHORT || type == Type.BOOLEAN || type == Type.CHAR){
123 throw new AssertionViolatedException("LocalVariables do not know about '"+type+"'. Use Type.INT instead.");
124 }
125 locals[i] = type;
126 }
127
128 /*
129 * Fulfills the general contract of Object.equals().
130 */
131 public boolean equals(Object o){
132 if (!(o instanceof LocalVariables)) return false;
133 LocalVariables lv = (LocalVariables) o;
134 if (this.locals.length != lv.locals.length) return false;
135 for (int i=0; i<this.locals.length; i++){
136 if (!this.locals[i].equals(lv.locals[i])){
137 //System.out.println(this.locals[i]+" is not "+lv.locals[i]);
138 return false;
139 }
140 }
141 return true;
142 }
143
144 /***
145 * Merges two local variables sets as described in the Java Virtual Machine Specification,
146 * Second Edition, section 4.9.2, page 146.
147 */
148 public void merge(LocalVariables lv){
149
150 if (this.locals.length != lv.locals.length){
151 throw new AssertionViolatedException("Merging LocalVariables of different size?!? From different methods or what?!?");
152 }
153
154 for (int i=0; i<locals.length; i++){
155 merge(lv, i);
156 }
157 }
158
159 /***
160 * Merges a single local variable.
161 *
162 * @see #merge(LocalVariables)
163 */
164 private void merge(LocalVariables lv, int i){
165
166 // We won't accept an unitialized object if we know it was initialized;
167 // compare vmspec2, 4.9.4, last paragraph.
168 if ( (!(locals[i] instanceof UninitializedObjectType)) && (lv.locals[i] instanceof UninitializedObjectType) ){
169 throw new StructuralCodeConstraintException("Backwards branch with an uninitialized object in the local variables detected.");
170 }
171 // Even harder, what about _different_ uninitialized object types?!
172 if ( (!(locals[i].equals(lv.locals[i]))) && (locals[i] instanceof UninitializedObjectType) && (lv.locals[i] instanceof UninitializedObjectType) ){
173 throw new StructuralCodeConstraintException("Backwards branch with an uninitialized object in the local variables detected.");
174 }
175 // If we just didn't know that it was initialized, we have now learned.
176 if (locals[i] instanceof UninitializedObjectType){
177 if (! (lv.locals[i] instanceof UninitializedObjectType)){
178 locals[i] = ((UninitializedObjectType) locals[i]).getInitialized();
179 }
180 }
181 if ((locals[i] instanceof ReferenceType) && (lv.locals[i] instanceof ReferenceType)){
182 if (! locals[i].equals(lv.locals[i])){ // needed in case of two UninitializedObjectType instances
183 Type sup = ((ReferenceType) locals[i]).getFirstCommonSuperclass((ReferenceType) (lv.locals[i]));
184
185 if (sup != null){
186 locals[i] = sup;
187 }
188 else{
189 // We should have checked this in Pass2!
190 throw new AssertionViolatedException("Could not load all the super classes of '"+locals[i]+"' and '"+lv.locals[i]+"'.");
191 }
192 }
193 }
194 else{
195 if (! (locals[i].equals(lv.locals[i])) ){
196 /*TODO
197 if ((locals[i] instanceof org.apache.bcel.generic.ReturnaddressType) && (lv.locals[i] instanceof org.apache.bcel.generic.ReturnaddressType)){
198 //System.err.println("merging "+locals[i]+" and "+lv.locals[i]);
199 throw new AssertionViolatedException("Merging different ReturnAddresses: '"+locals[i]+"' and '"+lv.locals[i]+"'.");
200 }
201 */
202 locals[i] = Type.UNKNOWN;
203 }
204 }
205 }
206
207 /***
208 * Returns a String representation of this object.
209 */
210 public String toString(){
211 String s = new String();
212 for (int i=0; i<locals.length; i++){
213 s += Integer.toString(i)+": "+locals[i]+"\n";
214 }
215 return s;
216 }
217
218 /***
219 * Replaces all occurences of u in this local variables set
220 * with an "initialized" ObjectType.
221 */
222 public void initializeObject(UninitializedObjectType u){
223 for (int i=0; i<locals.length; i++){
224 if (locals[i] == u){
225 locals[i] = u.getInitialized();
226 }
227 }
228 }
229 }
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