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    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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