001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.verifier.structurals;
019
020
021import java.io.PrintWriter;
022import java.io.StringWriter;
023import java.util.ArrayList;
024import java.util.List;
025import java.util.Random;
026import java.util.Vector;
027
028import org.apache.bcel.Const;
029import org.apache.bcel.Repository;
030import org.apache.bcel.classfile.JavaClass;
031import org.apache.bcel.classfile.Method;
032import org.apache.bcel.generic.ConstantPoolGen;
033import org.apache.bcel.generic.InstructionHandle;
034import org.apache.bcel.generic.JsrInstruction;
035import org.apache.bcel.generic.MethodGen;
036import org.apache.bcel.generic.ObjectType;
037import org.apache.bcel.generic.RET;
038import org.apache.bcel.generic.ReferenceType;
039import org.apache.bcel.generic.ReturnInstruction;
040import org.apache.bcel.generic.ReturnaddressType;
041import org.apache.bcel.generic.Type;
042import org.apache.bcel.verifier.PassVerifier;
043import org.apache.bcel.verifier.VerificationResult;
044import org.apache.bcel.verifier.Verifier;
045import org.apache.bcel.verifier.exc.AssertionViolatedException;
046import org.apache.bcel.verifier.exc.StructuralCodeConstraintException;
047import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
048
049/**
050 * This PassVerifier verifies a method of class file according to pass 3,
051 * so-called structural verification as described in The Java Virtual Machine
052 * Specification, 2nd edition.
053 * More detailed information is to be found at the do_verify() method's
054 * documentation.
055 *
056 * @see #do_verify()
057 */
058
059public final class Pass3bVerifier extends PassVerifier{
060    /* TODO:    Throughout pass 3b, upper halves of LONG and DOUBLE
061                        are represented by Type.UNKNOWN. This should be changed
062                        in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
063
064    /**
065     * An InstructionContextQueue is a utility class that holds
066     * (InstructionContext, ArrayList) pairs in a Queue data structure.
067     * This is used to hold information about InstructionContext objects
068     * externally --- i.e. that information is not saved inside the
069     * InstructionContext object itself. This is useful to save the
070     * execution path of the symbolic execution of the
071     * Pass3bVerifier - this is not information
072     * that belongs into the InstructionContext object itself.
073     * Only at "execute()"ing
074     * time, an InstructionContext object will get the current information
075     * we have about its symbolic execution predecessors.
076     */
077    private static final class InstructionContextQueue {
078        // The following two fields together represent the queue.
079        /** The first elements from pairs in the queue. */
080        private final List<InstructionContext> ics = new Vector<>();
081        /** The second elements from pairs in the queue. */
082        private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
083
084        /**
085         * Adds an (InstructionContext, ExecutionChain) pair to this queue.
086         *
087         * @param ic the InstructionContext
088         * @param executionChain the ExecutionChain
089         */
090        public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
091            ics.add(ic);
092            ecs.add(executionChain);
093        }
094
095        /**
096         * Tests if InstructionContext queue is empty.
097         *
098         * @return true if the InstructionContext queue is empty.
099         */
100        public boolean isEmpty() {
101            return ics.isEmpty();
102        }
103
104        /**
105         * Removes a specific (InstructionContext, ExecutionChain) pair from their respective queues.
106         *
107         * @param i the index of the items to be removed
108         */
109        public void remove(final int i) {
110            ics.remove(i);
111            ecs.remove(i);
112        }
113
114        /**
115         * Gets a specific InstructionContext from the queue.
116         *
117         * @param i the index of the item to be fetched
118         * @return the indicated InstructionContext
119         */
120        public InstructionContext getIC(final int i) {
121            return ics.get(i);
122        }
123
124        /**
125         * Gets a specific ExecutionChain from the queue.
126         *
127         * @param i the index of the item to be fetched
128         * @return the indicated ExecutionChain
129         */
130        public ArrayList<InstructionContext> getEC(final int i) {
131            return ecs.get(i);
132        }
133
134        /**
135         * Gets the size of the InstructionContext queue.
136         *
137         * @return the size of the InstructionQueue
138         */
139        public int size() {
140            return ics.size();
141        }
142    } // end Inner Class InstructionContextQueue
143
144    /** In DEBUG mode, the verification algorithm is not randomized. */
145    private static final boolean DEBUG = true;
146
147    /** The Verifier that created this. */
148    private final Verifier myOwner;
149
150    /** The method number to verify. */
151    private final int methodNo;
152
153    /**
154     * This class should only be instantiated by a Verifier.
155     *
156     * @see org.apache.bcel.verifier.Verifier
157     */
158    public Pass3bVerifier(final Verifier owner, final int method_no) {
159        myOwner = owner;
160        this.methodNo = method_no;
161    }
162
163    /**
164     * Whenever the outgoing frame
165     * situation of an InstructionContext changes, all its successors are
166     * put [back] into the queue [as if they were unvisited].
167     * The proof of termination is about the existence of a
168     * fix point of frame merging.
169     */
170    private void circulationPump(final MethodGen m,final ControlFlowGraph cfg, final InstructionContext start,
171            final Frame vanillaFrame, final InstConstraintVisitor icv, final ExecutionVisitor ev) {
172        final Random random = new Random();
173        final InstructionContextQueue icq = new InstructionContextQueue();
174
175        start.execute(vanillaFrame, new ArrayList<InstructionContext>(), icv, ev);
176        // new ArrayList() <=>    no Instruction was executed before
177        //                                    => Top-Level routine (no jsr call before)
178        icq.add(start, new ArrayList<InstructionContext>());
179
180        // LOOP!
181        while (!icq.isEmpty()) {
182            InstructionContext u;
183            ArrayList<InstructionContext> ec;
184            if (!DEBUG) {
185                final int r = random.nextInt(icq.size());
186                u = icq.getIC(r);
187                ec = icq.getEC(r);
188                icq.remove(r);
189            }
190            else{
191                u  = icq.getIC(0);
192                ec = icq.getEC(0);
193                icq.remove(0);
194            }
195
196            @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
197            final
198            ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) (ec.clone());
199            @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
200            final
201            ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) (ec.clone());
202            newchain.add(u);
203
204            if ((u.getInstruction().getInstruction()) instanceof RET) {
205//System.err.println(u);
206                // We can only follow _one_ successor, the one after the
207                // JSR that was recently executed.
208                final RET ret = (RET) (u.getInstruction().getInstruction());
209                final ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
210                final InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
211
212                // Sanity check
213                InstructionContext lastJSR = null;
214                int skip_jsr = 0;
215                for (int ss=oldchain.size()-1; ss >= 0; ss--) {
216                    if (skip_jsr < 0) {
217                        throw new AssertionViolatedException("More RET than JSR in execution chain?!");
218                    }
219//System.err.println("+"+oldchain.get(ss));
220                    if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction) {
221                        if (skip_jsr == 0) {
222                            lastJSR = oldchain.get(ss);
223                            break;
224                        }
225                        skip_jsr--;
226                    }
227                    if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof RET) {
228                        skip_jsr++;
229                    }
230                }
231                if (lastJSR == null) {
232                    throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
233                }
234                final JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
235                if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ) {
236                    throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+
237                        theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
238                }
239
240                if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
241                    @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
242                    final
243                    ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
244                    icq.add(theSuccessor, newchainClone);
245                }
246            }
247            else{// "not a ret"
248
249                // Normal successors. Add them to the queue of successors.
250                final InstructionContext[] succs = u.getSuccessors();
251                for (final InstructionContext v : succs) {
252                    if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
253                        @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
254                        final
255                        ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
256                        icq.add(v, newchainClone);
257                    }
258                }
259            }// end "not a ret"
260
261            // Exception Handlers. Add them to the queue of successors.
262            // [subroutines are never protected; mandated by JustIce]
263            final ExceptionHandler[] exc_hds = u.getExceptionHandlers();
264            for (final ExceptionHandler exc_hd : exc_hds) {
265                final InstructionContext v = cfg.contextOf(exc_hd.getHandlerStart());
266                // TODO: the "oldchain" and "newchain" is used to determine the subroutine
267                // we're in (by searching for the last JSR) by the InstructionContext
268                // implementation. Therefore, we should not use this chain mechanism
269                // when dealing with exception handlers.
270                // Example: a JSR with an exception handler as its successor does not
271                // mean we're in a subroutine if we go to the exception handler.
272                // We should address this problem later; by now we simply "cut" the chain
273                // by using an empty chain for the exception handlers.
274                //if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
275                // new OperandStack (u.getOutFrame().getStack().maxStack(),
276                // (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev) {
277                    //icq.add(v, (ArrayList) newchain.clone());
278                if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
279                        new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(),
280                        exc_hd.getExceptionType()==null? Type.THROWABLE : exc_hd.getExceptionType())),
281                        new ArrayList<InstructionContext>(), icv, ev)) {
282                    icq.add(v, new ArrayList<InstructionContext>());
283                }
284            }
285
286        }// while (!icq.isEmpty()) END
287
288        InstructionHandle ih = start.getInstruction();
289        do{
290            if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
291                final InstructionContext ic = cfg.contextOf(ih);
292                // TODO: This is buggy, we check only the top-level return instructions this way.
293                // Maybe some maniac returns from a method when in a subroutine?
294                final Frame f = ic.getOutFrame(new ArrayList<InstructionContext>());
295                final LocalVariables lvs = f.getLocals();
296                for (int i=0; i<lvs.maxLocals(); i++) {
297                    if (lvs.get(i) instanceof UninitializedObjectType) {
298                        this.addMessage("Warning: ReturnInstruction '"+ic+
299                            "' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
300                    }
301                }
302                final OperandStack os = f.getStack();
303                for (int i=0; i<os.size(); i++) {
304                    if (os.peek(i) instanceof UninitializedObjectType) {
305                        this.addMessage("Warning: ReturnInstruction '"+ic+
306                            "' may leave method with an uninitialized object on the operand stack '"+os+"'.");
307                    }
308                }
309                //see JVM $4.8.2
310                Type returnedType = null;
311                final OperandStack inStack = ic.getInFrame().getStack();
312                if (inStack.size() >= 1) {
313                    returnedType = inStack.peek();
314                } else {
315                    returnedType = Type.VOID;
316                }
317
318                if (returnedType != null) {
319                    if (returnedType instanceof ReferenceType) {
320                        try {
321                            if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
322                                invalidReturnTypeError(returnedType, m);
323                            }
324                        } catch (final ClassNotFoundException e) {
325                            // Don't know what do do now, so raise RuntimeException
326                            throw new IllegalArgumentException(e);
327                        }
328                    } else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
329                        invalidReturnTypeError(returnedType, m);
330                    }
331                }
332            }
333        } while ((ih = ih.getNext()) != null);
334
335     }
336
337    /**
338     * Throws an exception indicating the returned type is not compatible with the return type of the given method.
339     *
340     * @param returnedType the type of the returned expression
341     * @param m the method we are processing
342     * @throws StructuralCodeConstraintException always
343     * @since 6.0
344     */
345    public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
346        throw new StructuralCodeConstraintException(
347            "Returned type "+returnedType+" does not match Method's return type "+m.getReturnType());
348    }
349
350    /**
351     * Pass 3b implements the data flow analysis as described in the Java Virtual
352     * Machine Specification, Second Edition.
353     * Later versions will use LocalVariablesInfo objects to verify if the
354     * verifier-inferred types and the class file's debug information (LocalVariables
355     * attributes) match [TODO].
356     *
357     * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
358     * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
359     */
360    @Override
361    public VerificationResult do_verify() {
362        if (! myOwner.doPass3a(methodNo).equals(VerificationResult.VR_OK)) {
363            return VerificationResult.VR_NOTYET;
364        }
365
366        // Pass 3a ran before, so it's safe to assume the JavaClass object is
367        // in the BCEL repository.
368        JavaClass jc;
369        try {
370            jc = Repository.lookupClass(myOwner.getClassName());
371        } catch (final ClassNotFoundException e) {
372            // FIXME: maybe not the best way to handle this
373            throw new AssertionViolatedException("Missing class: " + e, e);
374        }
375
376        final ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
377        // Init Visitors
378        final InstConstraintVisitor icv = new InstConstraintVisitor();
379        icv.setConstantPoolGen(constantPoolGen);
380
381        final ExecutionVisitor ev = new ExecutionVisitor();
382        ev.setConstantPoolGen(constantPoolGen);
383
384        final Method[] methods = jc.getMethods(); // Method no "methodNo" exists, we ran Pass3a before on it!
385
386        try{
387
388            final MethodGen mg = new MethodGen(methods[methodNo], myOwner.getClassName(), constantPoolGen);
389
390            icv.setMethodGen(mg);
391
392            ////////////// DFA BEGINS HERE ////////////////
393            if (! (mg.isAbstract() || mg.isNative()) ) { // IF mg HAS CODE (See pass 2)
394
395                final ControlFlowGraph cfg = new ControlFlowGraph(mg);
396
397                // Build the initial frame situation for this method.
398                final Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
399                if ( !mg.isStatic() ) {
400                    if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
401                        Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
402                        f.getLocals().set(0, Frame.getThis());
403                    }
404                    else{
405                        Frame.setThis(null);
406                        f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
407                    }
408                }
409                final Type[] argtypes = mg.getArgumentTypes();
410                int twoslotoffset = 0;
411                for (int j=0; j<argtypes.length; j++) {
412                    if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE ||
413                        argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN) {
414                        argtypes[j] = Type.INT;
415                    }
416                    f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
417                    if (argtypes[j].getSize() == 2) {
418                        twoslotoffset++;
419                        f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
420                    }
421                }
422                circulationPump(mg,cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
423            }
424        }
425        catch (final VerifierConstraintViolatedException ce) {
426            ce.extendMessage("Constraint violated in method '"+methods[methodNo]+"':\n","");
427            return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
428        }
429        catch (final RuntimeException re) {
430            // These are internal errors
431
432            final StringWriter sw = new StringWriter();
433            final PrintWriter pw = new PrintWriter(sw);
434            re.printStackTrace(pw);
435
436            throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+
437                "', method '"+methods[methodNo]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n", re);
438        }
439        return VerificationResult.VR_OK;
440    }
441
442    /** Returns the method number as supplied when instantiating. */
443    public int getMethodNo() {
444        return methodNo;
445    }
446}