    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        private final List<InstructionContext> ics = new Vector<>();
    079        private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
    080        public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
    081            ics.add(ic);
    082            ecs.add(executionChain);
    083        }
    084        public boolean isEmpty() {
    085            return ics.isEmpty();
    086        }
    087        public void remove(final int i) {
    088            ics.remove(i);
    089            ecs.remove(i);
    090        }
    091        public InstructionContext getIC(final int i) {
    092            return ics.get(i);
    093        }
    094        public ArrayList<InstructionContext> getEC(final int i) {
    095            return ecs.get(i);
    096        }
    097        public int size() {
    098            return ics.size();
    099        }
    100    } // end Inner Class InstructionContextQueue
    101
    102    /** In DEBUG mode, the verification algorithm is not randomized. */
    103    private static final boolean DEBUG = true;
    104
    105    /** The Verifier that created this. */
    106    private final Verifier myOwner;
    107
    108    /** The method number to verify. */
    109    private final int method_no;
    110
    111    /**
    112     * This class should only be instantiated by a Verifier.
    113     *
    114     * @see org.apache.bcel.verifier.Verifier
    115     */
    116    public Pass3bVerifier(final Verifier owner, final int method_no) {
    117        myOwner = owner;
    118        this.method_no = method_no;
    119    }
    120
    121    /**
    122     * Whenever the outgoing frame
    123     * situation of an InstructionContext changes, all its successors are
    124     * put [back] into the queue [as if they were unvisited].
    125   * The proof of termination is about the existence of a
    126   * fix point of frame merging.
    127     */
    128    private void circulationPump(final MethodGen m,final ControlFlowGraph cfg, final InstructionContext start,
    129            final Frame vanillaFrame, final InstConstraintVisitor icv, final ExecutionVisitor ev) {
    130        final Random random = new Random();
    131        final InstructionContextQueue icq = new InstructionContextQueue();
    132
    133        start.execute(vanillaFrame, new ArrayList<InstructionContext>(), icv, ev);
    134        // new ArrayList() <=>    no Instruction was executed before
    135        //                                    => Top-Level routine (no jsr call before)
    136        icq.add(start, new ArrayList<InstructionContext>());
    137
    138        // LOOP!
    139        while (!icq.isEmpty()) {
    140            InstructionContext u;
    141            ArrayList<InstructionContext> ec;
    142            if (!DEBUG) {
    143                final int r = random.nextInt(icq.size());
    144                u = icq.getIC(r);
    145                ec = icq.getEC(r);
    146                icq.remove(r);
    147            }
    148            else{
    149                u  = icq.getIC(0);
    150                ec = icq.getEC(0);
    151                icq.remove(0);
    152            }
    153
    154            @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
    155            final
    156            ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) (ec.clone());
    157            @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
    158            final
    159            ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) (ec.clone());
    160            newchain.add(u);
    161
    162            if ((u.getInstruction().getInstruction()) instanceof RET) {
    163//System.err.println(u);
    164                // We can only follow _one_ successor, the one after the
    165                // JSR that was recently executed.
    166                final RET ret = (RET) (u.getInstruction().getInstruction());
    167                final ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
    168                final InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
    169
    170                // Sanity check
    171                InstructionContext lastJSR = null;
    172                int skip_jsr = 0;
    173                for (int ss=oldchain.size()-1; ss >= 0; ss--) {
    174                    if (skip_jsr < 0) {
    175                        throw new AssertionViolatedException("More RET than JSR in execution chain?!");
    176                    }
    177//System.err.println("+"+oldchain.get(ss));
    178                    if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction) {
    179                        if (skip_jsr == 0) {
    180                            lastJSR = oldchain.get(ss);
    181                            break;
    182                        }
    183                        skip_jsr--;
    184                    }
    185                    if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof RET) {
    186                        skip_jsr++;
    187                    }
    188                }
    189                if (lastJSR == null) {
    190                    throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
    191                }
    192                final JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
    193                if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ) {
    194                    throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+
    195                        theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
    196                }
    197
    198                if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
    199                    @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
    200                    final
    201                    ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
    202                    icq.add(theSuccessor, newchainClone);
    203                }
    204            }
    205            else{// "not a ret"
    206
    207                // Normal successors. Add them to the queue of successors.
    208                final InstructionContext[] succs = u.getSuccessors();
    209                for (final InstructionContext v : succs) {
    210                    if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
    211                        @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
    212                        final
    213                        ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
    214                        icq.add(v, newchainClone);
    215                    }
    216                }
    217            }// end "not a ret"
    218
    219            // Exception Handlers. Add them to the queue of successors.
    220            // [subroutines are never protected; mandated by JustIce]
    221            final ExceptionHandler[] exc_hds = u.getExceptionHandlers();
    222            for (final ExceptionHandler exc_hd : exc_hds) {
    223                final InstructionContext v = cfg.contextOf(exc_hd.getHandlerStart());
    224                // TODO: the "oldchain" and "newchain" is used to determine the subroutine
    225                // we're in (by searching for the last JSR) by the InstructionContext
    226                // implementation. Therefore, we should not use this chain mechanism
    227                // when dealing with exception handlers.
    228                // Example: a JSR with an exception handler as its successor does not
    229                // mean we're in a subroutine if we go to the exception handler.
    230                // We should address this problem later; by now we simply "cut" the chain
    231                // by using an empty chain for the exception handlers.
    232                //if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
    233                // new OperandStack (u.getOutFrame().getStack().maxStack(),
    234                // (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev) {
    235                    //icq.add(v, (ArrayList) newchain.clone());
    236                if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
    237                        new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(),
    238                        exc_hd.getExceptionType()==null? Type.THROWABLE : exc_hd.getExceptionType())),
    239                        new ArrayList<InstructionContext>(), icv, ev)) {
    240                    icq.add(v, new ArrayList<InstructionContext>());
    241                }
    242            }
    243
    244        }// while (!icq.isEmpty()) END
    245
    246        InstructionHandle ih = start.getInstruction();
    247        do{
    248            if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
    249                final InstructionContext ic = cfg.contextOf(ih);
    250                // TODO: This is buggy, we check only the top-level return instructions this way.
    251                // Maybe some maniac returns from a method when in a subroutine?
    252                final Frame f = ic.getOutFrame(new ArrayList<InstructionContext>());
    253                final LocalVariables lvs = f.getLocals();
    254                for (int i=0; i<lvs.maxLocals(); i++) {
    255                    if (lvs.get(i) instanceof UninitializedObjectType) {
    256                        this.addMessage("Warning: ReturnInstruction '"+ic+
    257                            "' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
    258                    }
    259                }
    260                final OperandStack os = f.getStack();
    261                for (int i=0; i<os.size(); i++) {
    262                    if (os.peek(i) instanceof UninitializedObjectType) {
    263                        this.addMessage("Warning: ReturnInstruction '"+ic+
    264                            "' may leave method with an uninitialized object on the operand stack '"+os+"'.");
    265                    }
    266                }
    267                //see JVM $4.8.2
    268                Type returnedType = null;
    269                final OperandStack inStack = ic.getInFrame().getStack();
    270                if (inStack.size() >= 1) {
    271                    returnedType = inStack.peek();
    272                } else {
    273                    returnedType = Type.VOID;
    274                }
    275
    276                if (returnedType != null) {
    277                    if (returnedType instanceof ReferenceType) {
    278                        try {
    279                            if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
    280                                invalidReturnTypeError(returnedType, m);
    281                            }
    282                        } catch (final ClassNotFoundException e) {
    283                            // Don't know what do do now, so raise RuntimeException
    284                            throw new RuntimeException(e);
    285                        }
    286                    } else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
    287                        invalidReturnTypeError(returnedType, m);
    288                    }
    289                }
    290            }
    291        } while ((ih = ih.getNext()) != null);
    292
    293     }
    294
    295    /**
    296     * Throws an exception indicating the returned type is not compatible with the return type of the given method
    297     * @throws StructuralCodeConstraintException always
    298     * @since 6.0
    299     */
    300    public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
    301        throw new StructuralCodeConstraintException(
    302            "Returned type "+returnedType+" does not match Method's return type "+m.getReturnType());
    303    }
    304
    305    /**
    306     * Pass 3b implements the data flow analysis as described in the Java Virtual
    307     * Machine Specification, Second Edition.
    308      * Later versions will use LocalVariablesInfo objects to verify if the
    309      * verifier-inferred types and the class file's debug information (LocalVariables
    310      * attributes) match [TODO].
    311      *
    312      * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
    313      * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
    314      */
    315    @Override
    316    public VerificationResult do_verify() {
    317        if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)) {
    318            return VerificationResult.VR_NOTYET;
    319        }
    320
    321        // Pass 3a ran before, so it's safe to assume the JavaClass object is
    322        // in the BCEL repository.
    323        JavaClass jc;
    324        try {
    325            jc = Repository.lookupClass(myOwner.getClassName());
    326        } catch (final ClassNotFoundException e) {
    327            // FIXME: maybe not the best way to handle this
    328            throw new AssertionViolatedException("Missing class: " + e, e);
    329        }
    330
    331        final ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
    332        // Init Visitors
    333        final InstConstraintVisitor icv = new InstConstraintVisitor();
    334        icv.setConstantPoolGen(constantPoolGen);
    335
    336        final ExecutionVisitor ev = new ExecutionVisitor();
    337        ev.setConstantPoolGen(constantPoolGen);
    338
    339        final Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
    340
    341        try{
    342
    343            final MethodGen mg = new MethodGen(methods[method_no], myOwner.getClassName(), constantPoolGen);
    344
    345            icv.setMethodGen(mg);
    346
    347            ////////////// DFA BEGINS HERE ////////////////
    348            if (! (mg.isAbstract() || mg.isNative()) ) { // IF mg HAS CODE (See pass 2)
    349
    350                final ControlFlowGraph cfg = new ControlFlowGraph(mg);
    351
    352                // Build the initial frame situation for this method.
    353                final Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
    354                if ( !mg.isStatic() ) {
    355                    if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
    356                        Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
    357                        f.getLocals().set(0, Frame.getThis());
    358                    }
    359                    else{
    360                        Frame.setThis(null);
    361                        f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
    362                    }
    363                }
    364                final Type[] argtypes = mg.getArgumentTypes();
    365                int twoslotoffset = 0;
    366                for (int j=0; j<argtypes.length; j++) {
    367                    if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE ||
    368                        argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN) {
    369                        argtypes[j] = Type.INT;
    370                    }
    371                    f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
    372                    if (argtypes[j].getSize() == 2) {
    373                        twoslotoffset++;
    374                        f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
    375                    }
    376                }
    377                circulationPump(mg,cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
    378            }
    379        }
    380        catch (final VerifierConstraintViolatedException ce) {
    381            ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
    382            return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
    383        }
    384        catch (final RuntimeException re) {
    385            // These are internal errors
    386
    387            final StringWriter sw = new StringWriter();
    388            final PrintWriter pw = new PrintWriter(sw);
    389            re.printStackTrace(pw);
    390
    391            throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+
    392                "', method '"+methods[method_no]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n", re);
    393        }
    394        return VerificationResult.VR_OK;
    395    }
    396
    397    /** Returns the method number as supplied when instantiating. */
    398    public int getMethodNo() {
    399        return method_no;
    400    }
    401}