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