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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 java.io.*;
    58  import java.util.ArrayList;
    59  import java.util.Random;
    60  import java.util.Vector;
    61  import org.apache.bcel.Constants;
    62  import org.apache.bcel.Repository;
    63  import org.apache.bcel.classfile.*;
    64  import org.apache.bcel.generic.*;
    65  import org.apache.bcel.verifier.*;
    66  import org.apache.bcel.verifier.statics.*;
    67  import org.apache.bcel.verifier.exc.*;
    68
    69  /***
    70   * This PassVerifier verifies a method of class file according to pass 3,
    71   * so-called structural verification as described in The Java Virtual Machine
    72   * Specification, 2nd edition.
    73   * More detailed information is to be found at the do_verify() method's
    74   * documentation.
    75   *
    76   * @version $Id: Pass3bVerifier.java,v 1.3 2002/07/04 21:44:42 enver Exp $
    77   * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
    78   * @see #do_verify()
    79   */
    80
    81  public final class Pass3bVerifier extends PassVerifier{
    82  	/* TODO:	Throughout pass 3b, upper halves of LONG and DOUBLE
    83  						are represented by Type.UNKNOWN. This should be changed
    84  						in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
    85
    86  	/***
    87  	 * An InstructionContextQueue is a utility class that holds
    88  	 * (InstructionContext, ArrayList) pairs in a Queue data structure.
    89  	 * This is used to hold information about InstructionContext objects
    90  	 * externally --- i.e. that information is not saved inside the
    91  	 * InstructionContext object itself. This is useful to save the
    92  	 * execution path of the symbolic execution of the
    93  	 * Pass3bVerifier - this is not information
    94  	 * that belongs into the InstructionContext object itself.
    95  	 * Only at "execute()"ing
    96  	 * time, an InstructionContext object will get the current information
    97  	 * we have about its symbolic execution predecessors.
    98  	 */
    99  	private static final class InstructionContextQueue{
    100 		private Vector ics = new Vector(); // Type: InstructionContext
    101 		private Vector ecs = new Vector(); // Type: ArrayList (of InstructionContext)
    102 		public void add(InstructionContext ic, ArrayList executionChain){
    103 			ics.add(ic);
    104 			ecs.add(executionChain);
    105 		}
    106 		public boolean isEmpty(){
    107 			return ics.isEmpty();
    108 		}
    109 		public void remove(){
    110 			this.remove(0);
    111 		}
    112 		public void remove(int i){
    113 			ics.remove(i);
    114 			ecs.remove(i);
    115 		}
    116 		public InstructionContext getIC(int i){
    117 			return (InstructionContext) ics.get(i);
    118 		}
    119 		public ArrayList getEC(int i){
    120 			return (ArrayList) ecs.get(i);
    121 		}
    122 		public int size(){
    123 			return ics.size();
    124 		}
    125 	} // end Inner Class InstructionContextQueue
    126
    127 	/*** In DEBUG mode, the verification algorithm is not randomized. */
    128 	private static final boolean DEBUG = true;
    129
    130 	/*** The Verifier that created this. */
    131 	private Verifier myOwner;
    132
    133 	/*** The method number to verify. */
    134 	private int method_no;
    135
    136 	/***
    137 	 * This class should only be instantiated by a Verifier.
    138 	 *
    139 	 * @see org.apache.bcel.verifier.Verifier
    140 	 */
    141 	public Pass3bVerifier(Verifier owner, int method_no){
    142 		myOwner = owner;
    143 		this.method_no = method_no;
    144 	}
    145
    146 	/***
    147 	 * Whenever the outgoing frame
    148 	 * situation of an InstructionContext changes, all its successors are
    149 	 * put [back] into the queue [as if they were unvisited].
    150    * The proof of termination is about the existence of a
    151    * fix point of frame merging.
    152 	 */
    153 	private void circulationPump(ControlFlowGraph cfg, InstructionContext start, Frame vanillaFrame, InstConstraintVisitor icv, ExecutionVisitor ev){
    154 		final Random random = new Random();
    155 		InstructionContextQueue icq = new InstructionContextQueue();
    156
    157 		start.execute(vanillaFrame, new ArrayList(), icv, ev);	// new ArrayList() <=>	no Instruction was executed before
    158 																									//									=> Top-Level routine (no jsr call before)
    159 		icq.add(start, new ArrayList());
    160
    161 		// LOOP!
    162 		while (!icq.isEmpty()){
    163 			InstructionContext u;
    164 			ArrayList ec;
    165 			if (!DEBUG){
    166 				int r = random.nextInt(icq.size());
    167 				u = icq.getIC(r);
    168 				ec = icq.getEC(r);
    169 				icq.remove(r);
    170 			}
    171 			else{
    172 				u  = icq.getIC(0);
    173 				ec = icq.getEC(0);
    174 				icq.remove(0);
    175 			}
    176
    177 			ArrayList oldchain = (ArrayList) (ec.clone());
    178 			ArrayList newchain = (ArrayList) (ec.clone());
    179 			newchain.add(u);
    180
    181 			if ((u.getInstruction().getInstruction()) instanceof RET){
    182 //System.err.println(u);
    183 				// We can only follow _one_ successor, the one after the
    184 				// JSR that was recently executed.
    185 				RET ret = (RET) (u.getInstruction().getInstruction());
    186 				ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
    187 				InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
    188
    189 				// Sanity check
    190 				InstructionContext lastJSR = null;
    191 				int skip_jsr = 0;
    192 				for (int ss=oldchain.size()-1; ss >= 0; ss--){
    193 					if (skip_jsr < 0){
    194 						throw new AssertionViolatedException("More RET than JSR in execution chain?!");
    195 					}
    196 //System.err.println("+"+oldchain.get(ss));
    197 					if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction){
    198 						if (skip_jsr == 0){
    199 							lastJSR = (InstructionContext) oldchain.get(ss);
    200 							break;
    201 						}
    202 						else{
    203 							skip_jsr--;
    204 						}
    205 					}
    206 					if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof RET){
    207 						skip_jsr++;
    208 					}
    209 				}
    210 				if (lastJSR == null){
    211 					throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
    212 				}
    213 				JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
    214 				if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ){
    215 					throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
    216 				}
    217
    218 				if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
    219 					icq.add(theSuccessor, (ArrayList) newchain.clone());
    220 				}
    221 			}
    222 			else{// "not a ret"
    223
    224 				// Normal successors. Add them to the queue of successors.
    225 				InstructionContext[] succs = u.getSuccessors();
    226 				for (int s=0; s<succs.length; s++){
    227 					InstructionContext v = succs[s];
    228 					if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
    229 						icq.add(v, (ArrayList) newchain.clone());
    230 					}
    231 				}
    232 			}// end "not a ret"
    233
    234 			// Exception Handlers. Add them to the queue of successors.
    235 			// [subroutines are never protected; mandated by JustIce]
    236 			ExceptionHandler[] exc_hds = u.getExceptionHandlers();
    237 			for (int s=0; s<exc_hds.length; s++){
    238 				InstructionContext v = cfg.contextOf(exc_hds[s].getHandlerStart());
    239 				// TODO: the "oldchain" and "newchain" is used to determine the subroutine
    240 				// we're in (by searching for the last JSR) by the InstructionContext
    241 				// implementation. Therefore, we should not use this chain mechanism
    242 				// when dealing with exception handlers.
    243 				// Example: a JSR with an exception handler as its successor does not
    244 				// mean we're in a subroutine if we go to the exception handler.
    245 				// We should address this problem later; by now we simply "cut" the chain
    246 				// by using an empty chain for the exception handlers.
    247 				//if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(), new OperandStack (u.getOutFrame().getStack().maxStack(), (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev){
    248 					//icq.add(v, (ArrayList) newchain.clone());
    249 				if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(), new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(), (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), new ArrayList(), icv, ev)){
    250 					icq.add(v, new ArrayList());
    251 				}
    252 			}
    253
    254 		}// while (!icq.isEmpty()) END
    255
    256 		InstructionHandle ih = start.getInstruction();
    257 		do{
    258 			if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
    259 				InstructionContext ic = cfg.contextOf(ih);
    260 				Frame f = ic.getOutFrame(new ArrayList()); // TODO: This is buggy, we check only the top-level return instructions this way. Maybe some maniac returns from a method when in a subroutine?
    261 				LocalVariables lvs = f.getLocals();
    262 				for (int i=0; i<lvs.maxLocals(); i++){
    263 					if (lvs.get(i) instanceof UninitializedObjectType){
    264 						this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
    265 					}
    266 				}
    267 				OperandStack os = f.getStack();
    268 				for (int i=0; i<os.size(); i++){
    269 					if (os.peek(i) instanceof UninitializedObjectType){
    270 						this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object on the operand stack '"+os+"'.");
    271 					}
    272 				}
    273 			}
    274 		}while ((ih = ih.getNext()) != null);
    275
    276  	}
    277
    278 	/***
    279 	 * Pass 3b implements the data flow analysis as described in the Java Virtual
    280 	 * Machine Specification, Second Edition.
    281  	 * Later versions will use LocalVariablesInfo objects to verify if the
    282  	 * verifier-inferred types and the class file's debug information (LocalVariables
    283  	 * attributes) match [TODO].
    284  	 *
    285  	 * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
    286  	 * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
    287  	 */
    288 	public VerificationResult do_verify(){
    289 		if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)){
    290 			return VerificationResult.VR_NOTYET;
    291 		}
    292
    293 		// Pass 3a ran before, so it's safe to assume the JavaClass object is
    294 		// in the BCEL repository.
    295 		JavaClass jc = Repository.lookupClass(myOwner.getClassName());
    296
    297 		ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
    298 		// Init Visitors
    299 		InstConstraintVisitor icv = new InstConstraintVisitor();
    300 		icv.setConstantPoolGen(constantPoolGen);
    301
    302 		ExecutionVisitor ev = new ExecutionVisitor();
    303 		ev.setConstantPoolGen(constantPoolGen);
    304
    305 		Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
    306
    307 		try{
    308
    309 			MethodGen mg = new MethodGen(methods[method_no], myOwner.getClassName(), constantPoolGen);
    310
    311 			icv.setMethodGen(mg);
    312
    313 			////////////// DFA BEGINS HERE ////////////////
    314 			if (! (mg.isAbstract() || mg.isNative()) ){ // IF mg HAS CODE (See pass 2)
    315
    316 				ControlFlowGraph cfg = new ControlFlowGraph(mg);
    317
    318 				// Build the initial frame situation for this method.
    319 				Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
    320 				if ( !mg.isStatic() ){
    321 					if (mg.getName().equals(Constants.CONSTRUCTOR_NAME)){
    322 						f._this = new UninitializedObjectType(new ObjectType(jc.getClassName()));
    323 						f.getLocals().set(0, f._this);
    324 					}
    325 					else{
    326 						f._this = null;
    327 						f.getLocals().set(0, new ObjectType(jc.getClassName()));
    328 					}
    329 				}
    330 				Type[] argtypes = mg.getArgumentTypes();
    331 				int twoslotoffset = 0;
    332 				for (int j=0; j<argtypes.length; j++){
    333 					if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE || argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN){
    334 						argtypes[j] = Type.INT;
    335 					}
    336 					f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
    337 					if (argtypes[j].getSize() == 2){
    338 						twoslotoffset++;
    339 						f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
    340 					}
    341 				}
    342 				circulationPump(cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
    343 			}
    344 		}
    345 		catch (VerifierConstraintViolatedException ce){
    346 			ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
    347 			return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
    348 		}
    349 		catch (RuntimeException re){
    350 			// These are internal errors
    351
    352 			StringWriter sw = new StringWriter();
    353 			PrintWriter pw = new PrintWriter(sw);
    354 			re.printStackTrace(pw);
    355
    356 			throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+"', method '"+methods[method_no]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n");
    357 		}
    358 		return VerificationResult.VR_OK;
    359 	}
    360
    361 	/*** Returns the method number as supplied when instantiating. */
    362 	public int getMethodNo(){
    363 		return method_no;
    364 	}
    365 }

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