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    1   /*
    2    * Copyright  2000-2004 The Apache Software Foundation
    3    *
    4    *  Licensed under the Apache License, Version 2.0 (the "License");
    5    *  you may not use this file except in compliance with the License.
    6    *  You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   *  Unless required by applicable law or agreed to in writing, software
    11   *  distributed under the License is distributed on an "AS IS" BASIS,
    12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   *  See the License for the specific language governing permissions and
    14   *  limitations under the License.
    15   *
    16   */
    17  package org.apache.bcel.verifier.structurals;
    18
    19
    20  import java.io.PrintWriter;
    21  import java.io.StringWriter;
    22  import java.util.ArrayList;
    23  import java.util.List;
    24  import java.util.Random;
    25  import java.util.Vector;
    26  import org.apache.bcel.Constants;
    27  import org.apache.bcel.Repository;
    28  import org.apache.bcel.classfile.JavaClass;
    29  import org.apache.bcel.classfile.Method;
    30  import org.apache.bcel.generic.ConstantPoolGen;
    31  import org.apache.bcel.generic.InstructionHandle;
    32  import org.apache.bcel.generic.JsrInstruction;
    33  import org.apache.bcel.generic.MethodGen;
    34  import org.apache.bcel.generic.ObjectType;
    35  import org.apache.bcel.generic.RET;
    36  import org.apache.bcel.generic.ReturnInstruction;
    37  import org.apache.bcel.generic.ReturnaddressType;
    38  import org.apache.bcel.generic.Type;
    39  import org.apache.bcel.verifier.PassVerifier;
    40  import org.apache.bcel.verifier.VerificationResult;
    41  import org.apache.bcel.verifier.Verifier;
    42  import org.apache.bcel.verifier.exc.AssertionViolatedException;
    43  import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
    44
    45  /***
    46   * This PassVerifier verifies a method of class file according to pass 3,
    47   * so-called structural verification as described in The Java Virtual Machine
    48   * Specification, 2nd edition.
    49   * More detailed information is to be found at the do_verify() method's
    50   * documentation.
    51   *
    52   * @version $Id: Pass3bVerifier.java 384759 2006-03-10 10:38:59Z tcurdt $
    53   * @author Enver Haase
    54   * @see #do_verify()
    55   */
    56
    57  public final class Pass3bVerifier extends PassVerifier{
    58  	/* TODO:	Throughout pass 3b, upper halves of LONG and DOUBLE
    59  						are represented by Type.UNKNOWN. This should be changed
    60  						in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
    61
    62  	/***
    63  	 * An InstructionContextQueue is a utility class that holds
    64  	 * (InstructionContext, ArrayList) pairs in a Queue data structure.
    65  	 * This is used to hold information about InstructionContext objects
    66  	 * externally --- i.e. that information is not saved inside the
    67  	 * InstructionContext object itself. This is useful to save the
    68  	 * execution path of the symbolic execution of the
    69  	 * Pass3bVerifier - this is not information
    70  	 * that belongs into the InstructionContext object itself.
    71  	 * Only at "execute()"ing
    72  	 * time, an InstructionContext object will get the current information
    73  	 * we have about its symbolic execution predecessors.
    74  	 */
    75  	private static final class InstructionContextQueue{
    76  		private List ics = new Vector(); // Type: InstructionContext
    77  		private List ecs = new Vector(); // Type: ArrayList (of InstructionContext)
    78  		public void add(InstructionContext ic, ArrayList executionChain){
    79  			ics.add(ic);
    80  			ecs.add(executionChain);
    81  		}
    82  		public boolean isEmpty(){
    83  			return ics.isEmpty();
    84  		}
    85  		public void remove(){
    86  			this.remove(0);
    87  		}
    88  		public void remove(int i){
    89  			ics.remove(i);
    90  			ecs.remove(i);
    91  		}
    92  		public InstructionContext getIC(int i){
    93  			return (InstructionContext) ics.get(i);
    94  		}
    95  		public ArrayList getEC(int i){
    96  			return (ArrayList) ecs.get(i);
    97  		}
    98  		public int size(){
    99  			return ics.size();
    100 		}
    101 	} // end Inner Class InstructionContextQueue
    102
    103 	/*** In DEBUG mode, the verification algorithm is not randomized. */
    104 	private static final boolean DEBUG = true;
    105
    106 	/*** The Verifier that created this. */
    107 	private Verifier myOwner;
    108
    109 	/*** The method number to verify. */
    110 	private int method_no;
    111
    112 	/***
    113 	 * This class should only be instantiated by a Verifier.
    114 	 *
    115 	 * @see org.apache.bcel.verifier.Verifier
    116 	 */
    117 	public Pass3bVerifier(Verifier owner, int method_no){
    118 		myOwner = owner;
    119 		this.method_no = method_no;
    120 	}
    121
    122 	/***
    123 	 * Whenever the outgoing frame
    124 	 * situation of an InstructionContext changes, all its successors are
    125 	 * put [back] into the queue [as if they were unvisited].
    126    * The proof of termination is about the existence of a
    127    * fix point of frame merging.
    128 	 */
    129 	private void circulationPump(ControlFlowGraph cfg, InstructionContext start, Frame vanillaFrame, InstConstraintVisitor icv, ExecutionVisitor ev){
    130 		final Random random = new Random();
    131 		InstructionContextQueue icq = new InstructionContextQueue();
    132
    133 		start.execute(vanillaFrame, new ArrayList(), icv, ev);	// new ArrayList() <=>	no Instruction was executed before
    134 																									//									=> Top-Level routine (no jsr call before)
    135 		icq.add(start, new ArrayList());
    136
    137 		// LOOP!
    138 		while (!icq.isEmpty()){
    139 			InstructionContext u;
    140 			ArrayList ec;
    141 			if (!DEBUG){
    142 				int r = random.nextInt(icq.size());
    143 				u = icq.getIC(r);
    144 				ec = icq.getEC(r);
    145 				icq.remove(r);
    146 			}
    147 			else{
    148 				u  = icq.getIC(0);
    149 				ec = icq.getEC(0);
    150 				icq.remove(0);
    151 			}
    152
    153 			ArrayList oldchain = (ArrayList) (ec.clone());
    154 			ArrayList newchain = (ArrayList) (ec.clone());
    155 			newchain.add(u);
    156
    157 			if ((u.getInstruction().getInstruction()) instanceof RET){
    158 //System.err.println(u);
    159 				// We can only follow _one_ successor, the one after the
    160 				// JSR that was recently executed.
    161 				RET ret = (RET) (u.getInstruction().getInstruction());
    162 				ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
    163 				InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
    164
    165 				// Sanity check
    166 				InstructionContext lastJSR = null;
    167 				int skip_jsr = 0;
    168 				for (int ss=oldchain.size()-1; ss >= 0; ss--){
    169 					if (skip_jsr < 0){
    170 						throw new AssertionViolatedException("More RET than JSR in execution chain?!");
    171 					}
    172 //System.err.println("+"+oldchain.get(ss));
    173 					if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction){
    174 						if (skip_jsr == 0){
    175 							lastJSR = (InstructionContext) oldchain.get(ss);
    176 							break;
    177 						}
    178 						else{
    179 							skip_jsr--;
    180 						}
    181 					}
    182 					if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof RET){
    183 						skip_jsr++;
    184 					}
    185 				}
    186 				if (lastJSR == null){
    187 					throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
    188 				}
    189 				JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
    190 				if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ){
    191 					throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
    192 				}
    193
    194 				if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
    195 					icq.add(theSuccessor, (ArrayList) newchain.clone());
    196 				}
    197 			}
    198 			else{// "not a ret"
    199
    200 				// Normal successors. Add them to the queue of successors.
    201 				InstructionContext[] succs = u.getSuccessors();
    202 				for (int s=0; s<succs.length; s++){
    203 					InstructionContext v = succs[s];
    204 					if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
    205 						icq.add(v, (ArrayList) newchain.clone());
    206 					}
    207 				}
    208 			}// end "not a ret"
    209
    210 			// Exception Handlers. Add them to the queue of successors.
    211 			// [subroutines are never protected; mandated by JustIce]
    212 			ExceptionHandler[] exc_hds = u.getExceptionHandlers();
    213 			for (int s=0; s<exc_hds.length; s++){
    214 				InstructionContext v = cfg.contextOf(exc_hds[s].getHandlerStart());
    215 				// TODO: the "oldchain" and "newchain" is used to determine the subroutine
    216 				// we're in (by searching for the last JSR) by the InstructionContext
    217 				// implementation. Therefore, we should not use this chain mechanism
    218 				// when dealing with exception handlers.
    219 				// Example: a JSR with an exception handler as its successor does not
    220 				// mean we're in a subroutine if we go to the exception handler.
    221 				// We should address this problem later; by now we simply "cut" the chain
    222 				// by using an empty chain for the exception handlers.
    223 				//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){
    224 					//icq.add(v, (ArrayList) newchain.clone());
    225 				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)){
    226 					icq.add(v, new ArrayList());
    227 				}
    228 			}
    229
    230 		}// while (!icq.isEmpty()) END
    231
    232 		InstructionHandle ih = start.getInstruction();
    233 		do{
    234 			if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
    235 				InstructionContext ic = cfg.contextOf(ih);
    236 				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?
    237 				LocalVariables lvs = f.getLocals();
    238 				for (int i=0; i<lvs.maxLocals(); i++){
    239 					if (lvs.get(i) instanceof UninitializedObjectType){
    240 						this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
    241 					}
    242 				}
    243 				OperandStack os = f.getStack();
    244 				for (int i=0; i<os.size(); i++){
    245 					if (os.peek(i) instanceof UninitializedObjectType){
    246 						this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object on the operand stack '"+os+"'.");
    247 					}
    248 				}
    249 			}
    250 		}while ((ih = ih.getNext()) != null);
    251
    252  	}
    253
    254 	/***
    255 	 * Pass 3b implements the data flow analysis as described in the Java Virtual
    256 	 * Machine Specification, Second Edition.
    257  	 * Later versions will use LocalVariablesInfo objects to verify if the
    258  	 * verifier-inferred types and the class file's debug information (LocalVariables
    259  	 * attributes) match [TODO].
    260  	 *
    261  	 * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
    262  	 * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
    263  	 */
    264 	public VerificationResult do_verify(){
    265 		if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)){
    266 			return VerificationResult.VR_NOTYET;
    267 		}
    268
    269 		// Pass 3a ran before, so it's safe to assume the JavaClass object is
    270 		// in the BCEL repository.
    271 		JavaClass jc;
    272 		try {
    273 			jc = Repository.lookupClass(myOwner.getClassName());
    274 		} catch (ClassNotFoundException e) {
    275 			// FIXME: maybe not the best way to handle this
    276 			throw new AssertionViolatedException("Missing class: " + e.toString());
    277 		}
    278
    279 		ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
    280 		// Init Visitors
    281 		InstConstraintVisitor icv = new InstConstraintVisitor();
    282 		icv.setConstantPoolGen(constantPoolGen);
    283
    284 		ExecutionVisitor ev = new ExecutionVisitor();
    285 		ev.setConstantPoolGen(constantPoolGen);
    286
    287 		Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
    288
    289 		try{
    290
    291 			MethodGen mg = new MethodGen(methods[method_no], myOwner.getClassName(), constantPoolGen);
    292
    293 			icv.setMethodGen(mg);
    294
    295 			////////////// DFA BEGINS HERE ////////////////
    296 			if (! (mg.isAbstract() || mg.isNative()) ){ // IF mg HAS CODE (See pass 2)
    297
    298 				ControlFlowGraph cfg = new ControlFlowGraph(mg);
    299
    300 				// Build the initial frame situation for this method.
    301 				Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
    302 				if ( !mg.isStatic() ){
    303 					if (mg.getName().equals(Constants.CONSTRUCTOR_NAME)){
    304 						Frame._this = new UninitializedObjectType(new ObjectType(jc.getClassName()));
    305 						f.getLocals().set(0, Frame._this);
    306 					}
    307 					else{
    308 						Frame._this = null;
    309 						f.getLocals().set(0, new ObjectType(jc.getClassName()));
    310 					}
    311 				}
    312 				Type[] argtypes = mg.getArgumentTypes();
    313 				int twoslotoffset = 0;
    314 				for (int j=0; j<argtypes.length; j++){
    315 					if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE || argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN){
    316 						argtypes[j] = Type.INT;
    317 					}
    318 					f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
    319 					if (argtypes[j].getSize() == 2){
    320 						twoslotoffset++;
    321 						f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
    322 					}
    323 				}
    324 				circulationPump(cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
    325 			}
    326 		}
    327 		catch (VerifierConstraintViolatedException ce){
    328 			ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
    329 			return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
    330 		}
    331 		catch (RuntimeException re){
    332 			// These are internal errors
    333
    334 			StringWriter sw = new StringWriter();
    335 			PrintWriter pw = new PrintWriter(sw);
    336 			re.printStackTrace(pw);
    337
    338 			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");
    339 		}
    340 		return VerificationResult.VR_OK;
    341 	}
    342
    343 	/*** Returns the method number as supplied when instantiating. */
    344 	public int getMethodNo(){
    345 		return method_no;
    346 	}
    347 }