Source code

    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.statics;
    018
    019import java.util.HashMap;
    020import java.util.HashSet;
    021import java.util.Locale;
    022import java.util.Map;
    023import java.util.Objects;
    024import java.util.Set;
    025
    026import org.apache.bcel.Const;
    027import org.apache.bcel.Constants;
    028import org.apache.bcel.Repository;
    029import org.apache.bcel.classfile.Attribute;
    030import org.apache.bcel.classfile.ClassFormatException;
    031import org.apache.bcel.classfile.Code;
    032import org.apache.bcel.classfile.CodeException;
    033import org.apache.bcel.classfile.Constant;
    034import org.apache.bcel.classfile.ConstantClass;
    035import org.apache.bcel.classfile.ConstantDouble;
    036import org.apache.bcel.classfile.ConstantFieldref;
    037import org.apache.bcel.classfile.ConstantFloat;
    038import org.apache.bcel.classfile.ConstantInteger;
    039import org.apache.bcel.classfile.ConstantInterfaceMethodref;
    040import org.apache.bcel.classfile.ConstantLong;
    041import org.apache.bcel.classfile.ConstantMethodref;
    042import org.apache.bcel.classfile.ConstantNameAndType;
    043import org.apache.bcel.classfile.ConstantPool;
    044import org.apache.bcel.classfile.ConstantString;
    045import org.apache.bcel.classfile.ConstantUtf8;
    046import org.apache.bcel.classfile.ConstantValue;
    047import org.apache.bcel.classfile.Deprecated;
    048import org.apache.bcel.classfile.DescendingVisitor;
    049import org.apache.bcel.classfile.EmptyVisitor;
    050import org.apache.bcel.classfile.ExceptionTable;
    051import org.apache.bcel.classfile.Field;
    052import org.apache.bcel.classfile.InnerClass;
    053import org.apache.bcel.classfile.InnerClasses;
    054import org.apache.bcel.classfile.JavaClass;
    055import org.apache.bcel.classfile.LineNumber;
    056import org.apache.bcel.classfile.LineNumberTable;
    057import org.apache.bcel.classfile.LocalVariable;
    058import org.apache.bcel.classfile.LocalVariableTable;
    059import org.apache.bcel.classfile.Method;
    060import org.apache.bcel.classfile.Node;
    061import org.apache.bcel.classfile.SourceFile;
    062import org.apache.bcel.classfile.Synthetic;
    063import org.apache.bcel.classfile.Unknown;
    064import org.apache.bcel.classfile.Utility;
    065import org.apache.bcel.generic.ArrayType;
    066import org.apache.bcel.generic.ObjectType;
    067import org.apache.bcel.generic.Type;
    068import org.apache.bcel.verifier.PassVerifier;
    069import org.apache.bcel.verifier.VerificationResult;
    070import org.apache.bcel.verifier.Verifier;
    071import org.apache.bcel.verifier.VerifierFactory;
    072import org.apache.bcel.verifier.exc.AssertionViolatedException;
    073import org.apache.bcel.verifier.exc.ClassConstraintException;
    074import org.apache.bcel.verifier.exc.LocalVariableInfoInconsistentException;
    075
    076/**
    077 * This PassVerifier verifies a class file according to pass 2 as described in The Java Virtual Machine Specification,
    078 * 2nd edition. More detailed information is to be found at the do_verify() method's documentation.
    079 *
    080 * @see #do_verify()
    081 */
    082public final class Pass2Verifier extends PassVerifier implements Constants {
    083
    084    /**
    085     * A Visitor class that ensures the constant pool satisfies the static constraints. The visitXXX() methods throw
    086     * ClassConstraintException instances otherwise.
    087     *
    088     * @see #constantPoolEntriesSatisfyStaticConstraints()
    089     */
    090    private final class CPESSC_Visitor extends EmptyVisitor {
    091        private final Class<?> CONST_Class;
    092
    093        /*
    094         * private Class<?> CONST_Fieldref; private Class<?> CONST_Methodref; private Class<?> CONST_InterfaceMethodref;
    095         */
    096        private final Class<?> CONST_String;
    097        private final Class<?> CONST_Integer;
    098        private final Class<?> CONST_Float;
    099        private final Class<?> CONST_Long;
    100        private final Class<?> CONST_Double;
    101        private final Class<?> CONST_NameAndType;
    102        private final Class<?> CONST_Utf8;
    103
    104        private final JavaClass jc;
    105        private final ConstantPool cp; // ==jc.getConstantPool() -- only here to save typing work and computing power.
    106        private final int cplen; // == cp.getLength() -- to save computing power.
    107        private final DescendingVisitor carrier;
    108
    109        private final Set<String> fieldNames = new HashSet<>();
    110        private final Set<String> fieldNamesAndDesc = new HashSet<>();
    111        private final Set<String> methodNamesAndDesc = new HashSet<>();
    112
    113        private CPESSC_Visitor(final JavaClass jc) {
    114            this.jc = jc;
    115            this.cp = jc.getConstantPool();
    116            this.cplen = cp.getLength();
    117
    118            this.CONST_Class = ConstantClass.class;
    119            /*
    120             * CONST_Fieldref = ConstantFieldref.class; CONST_Methodref = ConstantMethodref.class; CONST_InterfaceMethodref =
    121             * ConstantInterfaceMethodref.class;
    122             */
    123            this.CONST_String = ConstantString.class;
    124            this.CONST_Integer = ConstantInteger.class;
    125            this.CONST_Float = ConstantFloat.class;
    126            this.CONST_Long = ConstantLong.class;
    127            this.CONST_Double = ConstantDouble.class;
    128            this.CONST_NameAndType = ConstantNameAndType.class;
    129            this.CONST_Utf8 = ConstantUtf8.class;
    130
    131            this.carrier = new DescendingVisitor(jc, this);
    132            this.carrier.visit();
    133        }
    134
    135        private void checkIndex(final Node referrer, final int index, final Class<?> shouldbe) {
    136            if (index < 0 || index >= cplen) {
    137                throw new ClassConstraintException("Invalid index '" + index + "' used by '" + tostring(referrer) + "'.");
    138            }
    139            final Constant c = cp.getConstant(index);
    140            if (!shouldbe.isInstance(c)) {
    141                /* String isnot = shouldbe.toString().substring(shouldbe.toString().lastIndexOf(".")+1); //Cut all before last "." */
    142                throw new ClassConstraintException(
    143                    "Illegal constant '" + tostring(c) + "' at index '" + index + "'. '" + tostring(referrer) + "' expects a '" + shouldbe + "'.");
    144            }
    145        }
    146
    147        // SYNTHETIC: see above
    148        // DEPRECATED: see above
    149        /////////////////////////////////////////////////////////
    150        // method_info-structure-ATTRIBUTES (vmspec2 4.6, 4.7) //
    151        /////////////////////////////////////////////////////////
    152        @Override
    153        public void visitCode(final Code obj) {// vmspec2 4.7.3
    154            try {
    155                // No code attribute allowed for native or abstract methods: see visitMethod(Method).
    156                // Code array constraints are checked in Pass3 (3a and 3b).
    157
    158                checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    159
    160                final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    161                if (!name.equals("Code")) {
    162                    throw new ClassConstraintException("The Code attribute '" + tostring(obj) + "' is not correctly named 'Code' but '" + name + "'.");
    163                }
    164
    165                if (!(carrier.predecessor() instanceof Method)) {
    166                    addMessage(
    167                        "Code attribute '" + tostring(obj) + "' is not declared in a method_info structure but in '" + carrier.predecessor() + "'. Ignored.");
    168                    return;
    169                }
    170                final Method m = (Method) carrier.predecessor(); // we can assume this method was visited before;
    171                                                                 // i.e. the data consistency was verified.
    172
    173                if (obj.getCode().length == 0) {
    174                    throw new ClassConstraintException("Code array of Code attribute '" + tostring(obj) + "' (method '" + m + "') must not be empty.");
    175                }
    176
    177                // In JustIce, the check for correct offsets into the code array is delayed to Pass 3a.
    178                final CodeException[] excTable = obj.getExceptionTable();
    179                for (final CodeException element : excTable) {
    180                    final int excIndex = element.getCatchType();
    181                    if (excIndex != 0) { // if 0, it catches all Throwables
    182                        checkIndex(obj, excIndex, CONST_Class);
    183                        final ConstantClass cc = (ConstantClass) cp.getConstant(excIndex);
    184                        // cannot be sure this ConstantClass has already been visited (checked)!
    185                        checkIndex(cc, cc.getNameIndex(), CONST_Utf8);
    186                        final String cname = Utility.pathToPackage(((ConstantUtf8) cp.getConstant(cc.getNameIndex())).getBytes());
    187
    188                        Verifier v = VerifierFactory.getVerifier(cname);
    189                        VerificationResult vr = v.doPass1();
    190
    191                        if (vr != VerificationResult.VR_OK) {
    192                            throw new ClassConstraintException("Code attribute '" + tostring(obj) + "' (method '" + m + "') has an exception_table entry '"
    193                                + tostring(element) + "' that references '" + cname + "' as an Exception but it does not pass verification pass 1: " + vr);
    194                        }
    195                        // We cannot safely trust any other "instanceof" mechanism. We need to transitively verify
    196                        // the ancestor hierarchy.
    197                        JavaClass e = Repository.lookupClass(cname);
    198                        final JavaClass t = Repository.lookupClass(Type.THROWABLE.getClassName());
    199                        final JavaClass o = Repository.lookupClass(Type.OBJECT.getClassName());
    200                        while (e != o) {
    201                            if (e == t) {
    202                                break; // It's a subclass of Throwable, OKAY, leave.
    203                            }
    204
    205                            v = VerifierFactory.getVerifier(e.getSuperclassName());
    206                            vr = v.doPass1();
    207                            if (vr != VerificationResult.VR_OK) {
    208                                throw new ClassConstraintException("Code attribute '" + tostring(obj) + "' (method '" + m + "') has an exception_table entry '"
    209                                    + tostring(element) + "' that references '" + cname + "' as an Exception but '" + e.getSuperclassName()
    210                                    + "' in the ancestor hierachy does not pass verification pass 1: " + vr);
    211                            }
    212                            e = Repository.lookupClass(e.getSuperclassName());
    213                        }
    214                        if (e != t) {
    215                            throw new ClassConstraintException(
    216                                "Code attribute '" + tostring(obj) + "' (method '" + m + "') has an exception_table entry '" + tostring(element)
    217                                    + "' that references '" + cname + "' as an Exception but it is not a subclass of '" + t.getClassName() + "'.");
    218                        }
    219                    }
    220                }
    221
    222                // Create object for local variables information
    223                // This is highly unelegant due to usage of the Visitor pattern.
    224                // TODO: rework it.
    225                int methodNumber = -1;
    226                final Method[] ms = Repository.lookupClass(myOwner.getClassName()).getMethods();
    227                for (int mn = 0; mn < ms.length; mn++) {
    228                    if (m == ms[mn]) {
    229                        methodNumber = mn;
    230                        break;
    231                    }
    232                }
    233                // If the .class file is malformed the loop above may not find a method.
    234                // Try matching names instead of pointers.
    235                if (methodNumber < 0) {
    236                    for (int mn = 0; mn < ms.length; mn++) {
    237                        if (m.getName().equals(ms[mn].getName())) {
    238                            methodNumber = mn;
    239                            break;
    240                        }
    241                    }
    242                }
    243
    244                if (methodNumber < 0) { // Mmmmh. Can we be sure BCEL does not sometimes instantiate new objects?
    245                    throw new AssertionViolatedException("Could not find a known BCEL Method object in the corresponding BCEL JavaClass object.");
    246                }
    247                localVariablesInfos[methodNumber] = new LocalVariablesInfo(obj.getMaxLocals());
    248
    249                int numOfLvtAttribs = 0;
    250                // Now iterate through the attributes the Code attribute has.
    251                final Attribute[] atts = obj.getAttributes();
    252                for (final Attribute att : atts) {
    253                    if (!(att instanceof LineNumberTable) && !(att instanceof LocalVariableTable)) {
    254                        addMessage("Attribute '" + tostring(att) + "' as an attribute of Code attribute '" + tostring(obj) + "' (method '" + m
    255                            + "') is unknown and will therefore be ignored.");
    256                    } else {// LineNumberTable or LocalVariableTable
    257                        addMessage("Attribute '" + tostring(att) + "' as an attribute of Code attribute '" + tostring(obj) + "' (method '" + m
    258                            + "') will effectively be ignored and is only useful for debuggers and such.");
    259                    }
    260
    261                    // LocalVariableTable check (partially delayed to Pass3a).
    262                    // Here because its easier to collect the information of the
    263                    // (possibly more than one) LocalVariableTables belonging to
    264                    // one certain Code attribute.
    265                    if (att instanceof LocalVariableTable) { // checks conforming to vmspec2 4.7.9
    266
    267                        final LocalVariableTable lvt = (LocalVariableTable) att;
    268
    269                        checkIndex(lvt, lvt.getNameIndex(), CONST_Utf8);
    270
    271                        final String lvtname = ((ConstantUtf8) cp.getConstant(lvt.getNameIndex())).getBytes();
    272                        if (!lvtname.equals("LocalVariableTable")) {
    273                            throw new ClassConstraintException(
    274                                "The LocalVariableTable attribute '" + tostring(lvt) + "' is not correctly named 'LocalVariableTable' but '" + lvtname + "'.");
    275                        }
    276
    277                        // In JustIce, the check for correct offsets into the code array is delayed to Pass 3a.
    278                        for (final LocalVariable localvariable : lvt.getLocalVariableTable()) {
    279                            checkIndex(lvt, localvariable.getNameIndex(), CONST_Utf8);
    280                            final String localname = ((ConstantUtf8) cp.getConstant(localvariable.getNameIndex())).getBytes();
    281                            if (!validJavaIdentifier(localname)) {
    282                                throw new ClassConstraintException("LocalVariableTable '" + tostring(lvt) + "' references a local variable by the name '"
    283                                    + localname + "' which is not a legal Java simple name.");
    284                            }
    285
    286                            checkIndex(lvt, localvariable.getSignatureIndex(), CONST_Utf8);
    287                            final String localsig = ((ConstantUtf8) cp.getConstant(localvariable.getSignatureIndex())).getBytes(); // Local sig.(=descriptor)
    288                            Type t;
    289                            try {
    290                                t = Type.getType(localsig);
    291                            } catch (final ClassFormatException cfe) {
    292                                throw new ClassConstraintException("Illegal descriptor (==signature) '" + localsig + "' used by LocalVariable '"
    293                                    + tostring(localvariable) + "' referenced by '" + tostring(lvt) + "'.", cfe);
    294                            }
    295                            final int localindex = localvariable.getIndex();
    296                            if ((t == Type.LONG || t == Type.DOUBLE ? localindex + 1 : localindex) >= obj.getMaxLocals()) {
    297                                throw new ClassConstraintException(
    298                                    "LocalVariableTable attribute '" + tostring(lvt) + "' references a LocalVariable '" + tostring(localvariable)
    299                                        + "' with an index that exceeds the surrounding Code attribute's max_locals value of '" + obj.getMaxLocals() + "'.");
    300                            }
    301
    302                            try {
    303                                localVariablesInfos[methodNumber].add(localindex, localname, localvariable.getStartPC(), localvariable.getLength(), t);
    304                            } catch (final LocalVariableInfoInconsistentException lviie) {
    305                                throw new ClassConstraintException("Conflicting information in LocalVariableTable '" + tostring(lvt)
    306                                    + "' found in Code attribute '" + tostring(obj) + "' (method '" + tostring(m) + "'). " + lviie.getMessage(), lviie);
    307                            }
    308                        } // for all local variables localvariables[i] in the LocalVariableTable attribute atts[a] END
    309
    310                        numOfLvtAttribs++;
    311                        if (!m.isStatic() && numOfLvtAttribs > obj.getMaxLocals()) {
    312                            throw new ClassConstraintException("Number of LocalVariableTable attributes of Code attribute '" + tostring(obj) + "' (method '"
    313                                + tostring(m) + "') exceeds number of local variable slots '" + obj.getMaxLocals()
    314                                + "' ('There may be at most one LocalVariableTable attribute per local variable in the Code attribute.').");
    315                        }
    316                    } // if atts[a] instanceof LocalVariableTable END
    317                } // for all attributes atts[a] END
    318
    319            } catch (final ClassNotFoundException e) {
    320                // FIXME: this might not be the best way to handle missing classes.
    321                throw new AssertionViolatedException("Missing class: " + e, e);
    322            }
    323
    324        }// visitCode(Code) END
    325
    326        @Override
    327        public void visitCodeException(final CodeException obj) {
    328            // Code constraints are checked in Pass3 (3a and 3b).
    329            // This does not represent an Attribute but is only
    330            // related to internal BCEL data representation.
    331
    332            // see visitCode(Code)
    333        }
    334
    335        /////////////////////////////
    336        // CONSTANTS (vmspec2 4.4) //
    337        /////////////////////////////
    338        @Override
    339        public void visitConstantClass(final ConstantClass obj) {
    340            if (obj.getTag() != Const.CONSTANT_Class) {
    341                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    342            }
    343            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    344
    345        }
    346
    347        @Override
    348        public void visitConstantDouble(final ConstantDouble obj) {
    349            if (obj.getTag() != Const.CONSTANT_Double) {
    350                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    351            }
    352            // no indices to check
    353        }
    354
    355        @Override
    356        public void visitConstantFieldref(final ConstantFieldref obj) {
    357            if (obj.getTag() != Const.CONSTANT_Fieldref) {
    358                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    359            }
    360            checkIndex(obj, obj.getClassIndex(), CONST_Class);
    361            checkIndex(obj, obj.getNameAndTypeIndex(), CONST_NameAndType);
    362        }
    363
    364        @Override
    365        public void visitConstantFloat(final ConstantFloat obj) {
    366            if (obj.getTag() != Const.CONSTANT_Float) {
    367                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    368            }
    369            // no indices to check
    370        }
    371
    372        @Override
    373        public void visitConstantInteger(final ConstantInteger obj) {
    374            if (obj.getTag() != Const.CONSTANT_Integer) {
    375                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    376            }
    377            // no indices to check
    378        }
    379
    380        @Override
    381        public void visitConstantInterfaceMethodref(final ConstantInterfaceMethodref obj) {
    382            if (obj.getTag() != Const.CONSTANT_InterfaceMethodref) {
    383                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    384            }
    385            checkIndex(obj, obj.getClassIndex(), CONST_Class);
    386            checkIndex(obj, obj.getNameAndTypeIndex(), CONST_NameAndType);
    387        }
    388
    389        @Override
    390        public void visitConstantLong(final ConstantLong obj) {
    391            if (obj.getTag() != Const.CONSTANT_Long) {
    392                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    393            }
    394            // no indices to check
    395        }
    396
    397        @Override
    398        public void visitConstantMethodref(final ConstantMethodref obj) {
    399            if (obj.getTag() != Const.CONSTANT_Methodref) {
    400                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    401            }
    402            checkIndex(obj, obj.getClassIndex(), CONST_Class);
    403            checkIndex(obj, obj.getNameAndTypeIndex(), CONST_NameAndType);
    404        }
    405
    406        @Override
    407        public void visitConstantNameAndType(final ConstantNameAndType obj) {
    408            if (obj.getTag() != Const.CONSTANT_NameAndType) {
    409                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    410            }
    411            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    412            // checkIndex(obj, obj.getDescriptorIndex(), CONST_Utf8); //inconsistently named in BCEL, see below.
    413            checkIndex(obj, obj.getSignatureIndex(), CONST_Utf8);
    414        }
    415
    416        @Override
    417        public void visitConstantPool(final ConstantPool obj) {
    418            // No need to. We're piggybacked by the DescendingVisitor.
    419            // This does not represent an Attribute but is only
    420            // related to internal BCEL data representation.
    421        }
    422
    423        @Override
    424        public void visitConstantString(final ConstantString obj) {
    425            if (obj.getTag() != Const.CONSTANT_String) {
    426                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    427            }
    428            checkIndex(obj, obj.getStringIndex(), CONST_Utf8);
    429        }
    430
    431        @Override
    432        public void visitConstantUtf8(final ConstantUtf8 obj) {
    433            if (obj.getTag() != Const.CONSTANT_Utf8) {
    434                throw new ClassConstraintException("Wrong constant tag in '" + tostring(obj) + "'.");
    435            }
    436            // no indices to check
    437        }
    438
    439        ////////////////////////////////////////////////////////
    440        // field_info-structure-ATTRIBUTES (vmspec2 4.5, 4.7) //
    441        ////////////////////////////////////////////////////////
    442        @Override
    443        public void visitConstantValue(final ConstantValue obj) {// vmspec2 4.7.2
    444            // Despite its name, this really is an Attribute,
    445            // not a constant!
    446            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    447
    448            final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    449            if (!name.equals("ConstantValue")) {
    450                throw new ClassConstraintException(
    451                    "The ConstantValue attribute '" + tostring(obj) + "' is not correctly named 'ConstantValue' but '" + name + "'.");
    452            }
    453
    454            final Object pred = carrier.predecessor();
    455            if (pred instanceof Field) { // ConstantValue attributes are quite senseless if the predecessor is not a field.
    456                final Field f = (Field) pred;
    457                // Field constraints have been checked before -- so we are safe using their type information.
    458                final Type fieldType = Type.getType(((ConstantUtf8) cp.getConstant(f.getSignatureIndex())).getBytes());
    459
    460                final int index = obj.getConstantValueIndex();
    461                if (index < 0 || index >= cplen) {
    462                    throw new ClassConstraintException("Invalid index '" + index + "' used by '" + tostring(obj) + "'.");
    463                }
    464                final Constant c = cp.getConstant(index);
    465
    466                if (CONST_Long.isInstance(c) && fieldType.equals(Type.LONG) || CONST_Float.isInstance(c) && fieldType.equals(Type.FLOAT)) {
    467                    return;
    468                }
    469                if (CONST_Double.isInstance(c) && fieldType.equals(Type.DOUBLE)) {
    470                    return;
    471                }
    472                if (CONST_Integer.isInstance(c) && (fieldType.equals(Type.INT) || fieldType.equals(Type.SHORT) || fieldType.equals(Type.CHAR)
    473                    || fieldType.equals(Type.BYTE) || fieldType.equals(Type.BOOLEAN))) {
    474                    return;
    475                }
    476                if (CONST_String.isInstance(c) && fieldType.equals(Type.STRING)) {
    477                    return;
    478                }
    479
    480                throw new ClassConstraintException("Illegal type of ConstantValue '" + obj + "' embedding Constant '" + c + "'. It is referenced by field '"
    481                    + tostring(f) + "' expecting a different type: '" + fieldType + "'.");
    482            }
    483        }
    484
    485        @Override
    486        public void visitDeprecated(final Deprecated obj) {// vmspec2 4.7.10
    487            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    488
    489            final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    490            if (!name.equals("Deprecated")) {
    491                throw new ClassConstraintException("The Deprecated attribute '" + tostring(obj) + "' is not correctly named 'Deprecated' but '" + name + "'.");
    492            }
    493        }
    494
    495        @Override
    496        public void visitExceptionTable(final ExceptionTable obj) {// vmspec2 4.7.4
    497            try {
    498                // incorrectly named, it's the Exceptions attribute (vmspec2 4.7.4)
    499                checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    500
    501                final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    502                if (!name.equals("Exceptions")) {
    503                    throw new ClassConstraintException(
    504                        "The Exceptions attribute '" + tostring(obj) + "' is not correctly named 'Exceptions' but '" + name + "'.");
    505                }
    506
    507                final int[] excIndices = obj.getExceptionIndexTable();
    508
    509                for (final int excIndice : excIndices) {
    510                    checkIndex(obj, excIndice, CONST_Class);
    511
    512                    final ConstantClass cc = (ConstantClass) cp.getConstant(excIndice);
    513                    checkIndex(cc, cc.getNameIndex(), CONST_Utf8); // can't be sure this ConstantClass has already been visited (checked)!
    514                    // convert internal notation on-the-fly to external notation:
    515                    final String cname = Utility.pathToPackage(((ConstantUtf8) cp.getConstant(cc.getNameIndex())).getBytes());
    516
    517                    Verifier v = VerifierFactory.getVerifier(cname);
    518                    VerificationResult vr = v.doPass1();
    519
    520                    if (vr != VerificationResult.VR_OK) {
    521                        throw new ClassConstraintException("Exceptions attribute '" + tostring(obj) + "' references '" + cname
    522                            + "' as an Exception but it does not pass verification pass 1: " + vr);
    523                    }
    524                    // We cannot safely trust any other "instanceof" mechanism. We need to transitively verify
    525                    // the ancestor hierarchy.
    526                    JavaClass e = Repository.lookupClass(cname);
    527                    final JavaClass t = Repository.lookupClass(Type.THROWABLE.getClassName());
    528                    final JavaClass o = Repository.lookupClass(Type.OBJECT.getClassName());
    529                    while (e != o) {
    530                        if (e == t) {
    531                            break; // It's a subclass of Throwable, OKAY, leave.
    532                        }
    533
    534                        v = VerifierFactory.getVerifier(e.getSuperclassName());
    535                        vr = v.doPass1();
    536                        if (vr != VerificationResult.VR_OK) {
    537                            throw new ClassConstraintException("Exceptions attribute '" + tostring(obj) + "' references '" + cname + "' as an Exception but '"
    538                                + e.getSuperclassName() + "' in the ancestor hierachy does not pass verification pass 1: " + vr);
    539                        }
    540                        e = Repository.lookupClass(e.getSuperclassName());
    541                    }
    542                    if (e != t) {
    543                        throw new ClassConstraintException("Exceptions attribute '" + tostring(obj) + "' references '" + cname
    544                            + "' as an Exception but it is not a subclass of '" + t.getClassName() + "'.");
    545                    }
    546                }
    547
    548            } catch (final ClassNotFoundException e) {
    549                // FIXME: this might not be the best way to handle missing classes.
    550                throw new AssertionViolatedException("Missing class: " + e, e);
    551            }
    552        }
    553
    554        //////////////////////////
    555        // FIELDS (vmspec2 4.5) //
    556        //////////////////////////
    557        @Override
    558        public void visitField(final Field obj) {
    559
    560            if (jc.isClass()) {
    561                int maxone = 0;
    562                if (obj.isPrivate()) {
    563                    maxone++;
    564                }
    565                if (obj.isProtected()) {
    566                    maxone++;
    567                }
    568                if (obj.isPublic()) {
    569                    maxone++;
    570                }
    571                if (maxone > 1) {
    572                    throw new ClassConstraintException(
    573                        "Field '" + tostring(obj) + "' must only have at most one of its ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC modifiers set.");
    574                }
    575
    576                if (obj.isFinal() && obj.isVolatile()) {
    577                    throw new ClassConstraintException(
    578                        "Field '" + tostring(obj) + "' must only have at most one of its ACC_FINAL, ACC_VOLATILE modifiers set.");
    579                }
    580            } else { // isInterface!
    581                if (!obj.isPublic()) {
    582                    throw new ClassConstraintException("Interface field '" + tostring(obj) + "' must have the ACC_PUBLIC modifier set but hasn't!");
    583                }
    584                if (!obj.isStatic()) {
    585                    throw new ClassConstraintException("Interface field '" + tostring(obj) + "' must have the ACC_STATIC modifier set but hasn't!");
    586                }
    587                if (!obj.isFinal()) {
    588                    throw new ClassConstraintException("Interface field '" + tostring(obj) + "' must have the ACC_FINAL modifier set but hasn't!");
    589                }
    590            }
    591
    592            if ((obj.getAccessFlags() & ~(Const.ACC_PUBLIC | Const.ACC_PRIVATE | Const.ACC_PROTECTED | Const.ACC_STATIC | Const.ACC_FINAL | Const.ACC_VOLATILE |
    593                Const.ACC_TRANSIENT)) > 0) {
    594                addMessage("Field '" + tostring(obj) + "' has access flag(s) other than ACC_PUBLIC, ACC_PRIVATE, ACC_PROTECTED,"
    595                    + " ACC_STATIC, ACC_FINAL, ACC_VOLATILE, ACC_TRANSIENT set (ignored).");
    596            }
    597
    598            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    599
    600            final String name = obj.getName();
    601            if (!validFieldName(name)) {
    602                throw new ClassConstraintException("Field '" + tostring(obj) + "' has illegal name '" + obj.getName() + "'.");
    603            }
    604
    605            // A descriptor is often named signature in BCEL
    606            checkIndex(obj, obj.getSignatureIndex(), CONST_Utf8);
    607
    608            final String sig = ((ConstantUtf8) cp.getConstant(obj.getSignatureIndex())).getBytes(); // Field or Method sig.(=descriptor)
    609
    610            try {
    611                Type.getType(sig); /* Don't need the return value */
    612            } catch (final ClassFormatException cfe) {
    613                throw new ClassConstraintException("Illegal descriptor (==signature) '" + sig + "' used by '" + tostring(obj) + "'.", cfe);
    614            }
    615
    616            final String nameanddesc = name + sig;
    617            if (fieldNamesAndDesc.contains(nameanddesc)) {
    618                throw new ClassConstraintException("No two fields (like '" + tostring(obj) + "') are allowed have same names and descriptors!");
    619            }
    620            if (fieldNames.contains(name)) {
    621                addMessage("More than one field of name '" + name + "' detected (but with different type descriptors). This is very unusual.");
    622            }
    623            fieldNamesAndDesc.add(nameanddesc);
    624            fieldNames.add(name);
    625
    626            final Attribute[] atts = obj.getAttributes();
    627            for (final Attribute att : atts) {
    628                if (!(att instanceof ConstantValue) && !(att instanceof Synthetic) && !(att instanceof Deprecated)) {
    629                    addMessage("Attribute '" + tostring(att) + "' as an attribute of Field '" + tostring(obj) + "' is unknown and will therefore be ignored.");
    630                }
    631                if (!(att instanceof ConstantValue)) {
    632                    addMessage("Attribute '" + tostring(att) + "' as an attribute of Field '" + tostring(obj)
    633                        + "' is not a ConstantValue and is therefore only of use for debuggers and such.");
    634                }
    635            }
    636        }
    637
    638        @Override
    639        public void visitInnerClass(final InnerClass obj) {
    640            // This does not represent an Attribute but is only
    641            // related to internal BCEL data representation.
    642        }
    643
    644        @Override
    645        public void visitInnerClasses(final InnerClasses innerClasses) {// vmspec2 4.7.5
    646
    647            // exactly one InnerClasses attr per ClassFile if some inner class is refernced: see visitJavaClass()
    648
    649            checkIndex(innerClasses, innerClasses.getNameIndex(), CONST_Utf8);
    650
    651            final String name = ((ConstantUtf8) cp.getConstant(innerClasses.getNameIndex())).getBytes();
    652            if (!name.equals("InnerClasses")) {
    653                throw new ClassConstraintException(
    654                    "The InnerClasses attribute '" + tostring(innerClasses) + "' is not correctly named 'InnerClasses' but '" + name + "'.");
    655            }
    656
    657            innerClasses.forEach(ic -> {
    658                checkIndex(innerClasses, ic.getInnerClassIndex(), CONST_Class);
    659                final int outerIdx = ic.getOuterClassIndex();
    660                if (outerIdx != 0) {
    661                    checkIndex(innerClasses, outerIdx, CONST_Class);
    662                }
    663                final int innernameIdx = ic.getInnerNameIndex();
    664                if (innernameIdx != 0) {
    665                    checkIndex(innerClasses, innernameIdx, CONST_Utf8);
    666                }
    667                int acc = ic.getInnerAccessFlags();
    668                acc = acc & ~(Const.ACC_PUBLIC | Const.ACC_PRIVATE | Const.ACC_PROTECTED | Const.ACC_STATIC | Const.ACC_FINAL | Const.ACC_INTERFACE |
    669                    Const.ACC_ABSTRACT);
    670                if (acc != 0) {
    671                    addMessage("Unknown access flag for inner class '" + tostring(ic) + "' set (InnerClasses attribute '" + tostring(innerClasses) + "').");
    672                }
    673            });
    674            // Semantical consistency is not yet checked by Sun, see vmspec2 4.7.5.
    675            // [marked TODO in JustIce]
    676        }
    677
    678        ///////////////////////////////////////
    679        // ClassFile structure (vmspec2 4.1) //
    680        ///////////////////////////////////////
    681        @Override
    682        public void visitJavaClass(final JavaClass obj) {
    683            final Attribute[] atts = obj.getAttributes();
    684            boolean foundSourceFile = false;
    685            boolean foundInnerClasses = false;
    686
    687            // Is there an InnerClass referenced?
    688            // This is a costly check; existing verifiers don't do it!
    689            final boolean hasInnerClass = new InnerClassDetector(jc).innerClassReferenced();
    690
    691            for (final Attribute att : atts) {
    692                if (!(att instanceof SourceFile) && !(att instanceof Deprecated) && !(att instanceof InnerClasses) && !(att instanceof Synthetic)) {
    693                    addMessage("Attribute '" + tostring(att) + "' as an attribute of the ClassFile structure '" + tostring(obj)
    694                        + "' is unknown and will therefore be ignored.");
    695                }
    696
    697                if (att instanceof SourceFile) {
    698                    if (foundSourceFile) {
    699                        throw new ClassConstraintException(
    700                            "A ClassFile structure (like '" + tostring(obj) + "') may have no more than one SourceFile attribute."); // vmspec2 4.7.7
    701                    }
    702                    foundSourceFile = true;
    703                }
    704
    705                if (att instanceof InnerClasses) {
    706                    if (!foundInnerClasses) {
    707                        foundInnerClasses = true;
    708                    } else if (hasInnerClass) {
    709                        throw new ClassConstraintException("A Classfile structure (like '" + tostring(obj) + "') must have exactly one InnerClasses attribute"
    710                            + " if at least one Inner Class is referenced (which is the case)." + " More than one InnerClasses attribute was found.");
    711                    }
    712                    if (!hasInnerClass) {
    713                        addMessage("No referenced Inner Class found, but InnerClasses attribute '" + tostring(att)
    714                            + "' found. Strongly suggest removal of that attribute.");
    715                    }
    716                }
    717
    718            }
    719            if (hasInnerClass && !foundInnerClasses) {
    720                // throw new ClassConstraintException("A Classfile structure (like '"+tostring(obj)+
    721                // "') must have exactly one InnerClasses attribute if at least one Inner Class is referenced (which is the case)."+
    722                // " No InnerClasses attribute was found.");
    723                // vmspec2, page 125 says it would be a constraint: but existing verifiers
    724                // don't check it and javac doesn't satisfy it when it comes to anonymous
    725                // inner classes
    726                addMessage("A Classfile structure (like '" + tostring(obj)
    727                    + "') must have exactly one InnerClasses attribute if at least one Inner Class is referenced (which is the case)."
    728                    + " No InnerClasses attribute was found.");
    729            }
    730        }
    731
    732        @Override
    733        public void visitLineNumber(final LineNumber obj) {
    734            // This does not represent an Attribute but is only
    735            // related to internal BCEL data representation.
    736
    737            // see visitLineNumberTable(LineNumberTable)
    738        }
    739
    740        // SYNTHETIC: see above
    741        // DEPRECATED: see above
    742        //////////////////////////////////////////////////////////////
    743        // code_attribute-structure-ATTRIBUTES (vmspec2 4.7.3, 4.7) //
    744        //////////////////////////////////////////////////////////////
    745        @Override
    746        public void visitLineNumberTable(final LineNumberTable obj) {// vmspec2 4.7.8
    747            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    748
    749            final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    750            if (!name.equals("LineNumberTable")) {
    751                throw new ClassConstraintException(
    752                    "The LineNumberTable attribute '" + tostring(obj) + "' is not correctly named 'LineNumberTable' but '" + name + "'.");
    753            }
    754
    755            // In JustIce,this check is delayed to Pass 3a.
    756            // LineNumber[] linenumbers = obj.getLineNumberTable();
    757            // ...validity check...
    758
    759        }
    760
    761        //////////
    762        // BCEL //
    763        //////////
    764        @Override
    765        public void visitLocalVariable(final LocalVariable obj) {
    766            // This does not represent an Attribute but is only
    767            // related to internal BCEL data representation.
    768
    769            // see visitLocalVariableTable(LocalVariableTable)
    770        }
    771
    772        @Override
    773        public void visitLocalVariableTable(final LocalVariableTable obj) {// vmspec2 4.7.9
    774            // In JustIce,this check is partially delayed to Pass 3a.
    775            // The other part can be found in the visitCode(Code) method.
    776        }
    777
    778        ///////////////////////////
    779        // METHODS (vmspec2 4.6) //
    780        ///////////////////////////
    781        @Override
    782        public void visitMethod(final Method obj) {
    783
    784            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    785
    786            final String name = obj.getName();
    787            if (!validMethodName(name, true)) {
    788                throw new ClassConstraintException("Method '" + tostring(obj) + "' has illegal name '" + name + "'.");
    789            }
    790
    791            // A descriptor is often named signature in BCEL
    792            checkIndex(obj, obj.getSignatureIndex(), CONST_Utf8);
    793
    794            final String sig = ((ConstantUtf8) cp.getConstant(obj.getSignatureIndex())).getBytes(); // Method's signature(=descriptor)
    795
    796            Type t;
    797            Type[] ts; // needed below the try block.
    798            try {
    799                t = Type.getReturnType(sig);
    800                ts = Type.getArgumentTypes(sig);
    801            } catch (final ClassFormatException cfe) {
    802                throw new ClassConstraintException("Illegal descriptor (==signature) '" + sig + "' used by Method '" + tostring(obj) + "'.", cfe);
    803            }
    804
    805            // Check if referenced objects exist.
    806            Type act = t;
    807            if (act instanceof ArrayType) {
    808                act = ((ArrayType) act).getBasicType();
    809            }
    810            if (act instanceof ObjectType) {
    811                final Verifier v = VerifierFactory.getVerifier(((ObjectType) act).getClassName());
    812                final VerificationResult vr = v.doPass1();
    813                if (vr != VerificationResult.VR_OK) {
    814                    throw new ClassConstraintException(
    815                        "Method '" + tostring(obj) + "' has a return type that does not pass verification pass 1: '" + vr + "'.");
    816                }
    817            }
    818
    819            for (final Type element : ts) {
    820                act = element;
    821                if (act instanceof ArrayType) {
    822                    act = ((ArrayType) act).getBasicType();
    823                }
    824                if (act instanceof ObjectType) {
    825                    final Verifier v = VerifierFactory.getVerifier(((ObjectType) act).getClassName());
    826                    final VerificationResult vr = v.doPass1();
    827                    if (vr != VerificationResult.VR_OK) {
    828                        throw new ClassConstraintException(
    829                            "Method '" + tostring(obj) + "' has an argument type that does not pass verification pass 1: '" + vr + "'.");
    830                    }
    831                }
    832            }
    833
    834            // Nearly forgot this! Funny return values are allowed, but a non-empty arguments list makes a different method out of
    835            // it!
    836            if (name.equals(Const.STATIC_INITIALIZER_NAME) && ts.length != 0) {
    837                throw new ClassConstraintException("Method '" + tostring(obj) + "' has illegal name '" + name + "'."
    838                    + " Its name resembles the class or interface initialization method" + " which it isn't because of its arguments (==descriptor).");
    839            }
    840
    841            if (jc.isClass()) {
    842                int maxone = 0;
    843                if (obj.isPrivate()) {
    844                    maxone++;
    845                }
    846                if (obj.isProtected()) {
    847                    maxone++;
    848                }
    849                if (obj.isPublic()) {
    850                    maxone++;
    851                }
    852                if (maxone > 1) {
    853                    throw new ClassConstraintException(
    854                        "Method '" + tostring(obj) + "' must only have at most one of its ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC modifiers set.");
    855                }
    856
    857                if (obj.isAbstract()) {
    858                    if (obj.isFinal()) {
    859                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_FINAL modifier set.");
    860                    }
    861                    if (obj.isNative()) {
    862                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_NATIVE modifier set.");
    863                    }
    864                    if (obj.isPrivate()) {
    865                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_PRIVATE modifier set.");
    866                    }
    867                    if (obj.isStatic()) {
    868                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_STATIC modifier set.");
    869                    }
    870                    if (obj.isStrictfp()) {
    871                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_STRICT modifier set.");
    872                    }
    873                    if (obj.isSynchronized()) {
    874                        throw new ClassConstraintException("Abstract method '" + tostring(obj) + "' must not have the ACC_SYNCHRONIZED modifier set.");
    875                    }
    876                }
    877
    878                // A specific instance initialization method... (vmspec2,Page 116).
    879                // ..may have at most one of ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC set: is checked above.
    880                // ..may also have ACC_STRICT set, but none of the other flags in table 4.5 (vmspec2, page 115)
    881                if (name.equals(Const.CONSTRUCTOR_NAME) && (obj.isStatic() || obj.isFinal() || obj.isSynchronized() || obj.isNative() || obj.isAbstract())) {
    882                    throw new ClassConstraintException("Instance initialization method '" + tostring(obj) + "' must not have"
    883                            + " any of the ACC_STATIC, ACC_FINAL, ACC_SYNCHRONIZED, ACC_NATIVE, ACC_ABSTRACT modifiers set.");
    884                }
    885            } else if (!name.equals(Const.STATIC_INITIALIZER_NAME)) {// vmspec2, p.116, 2nd paragraph
    886                if (jc.getMajor() >= Const.MAJOR_1_8) {
    887                    if (obj.isPublic() == obj.isPrivate()) {
    888                        throw new ClassConstraintException(
    889                            "Interface method '" + tostring(obj) + "' must have" + " exactly one of its ACC_PUBLIC and ACC_PRIVATE modifiers set.");
    890                    }
    891                    if (obj.isProtected() || obj.isFinal() || obj.isSynchronized() || obj.isNative()) {
    892                        throw new ClassConstraintException("Interface method '" + tostring(obj) + "' must not have"
    893                            + " any of the ACC_PROTECTED, ACC_FINAL, ACC_SYNCHRONIZED, or ACC_NATIVE modifiers set.");
    894                    }
    895
    896                } else {
    897                    if (!obj.isPublic()) {
    898                        throw new ClassConstraintException("Interface method '" + tostring(obj) + "' must have the ACC_PUBLIC modifier set but hasn't!");
    899                    }
    900                    if (!obj.isAbstract()) {
    901                        throw new ClassConstraintException("Interface method '" + tostring(obj) + "' must have the ACC_ABSTRACT modifier set but hasn't!");
    902                    }
    903                    if (obj.isPrivate() || obj.isProtected() || obj.isStatic() || obj.isFinal() || obj.isSynchronized() || obj.isNative() || obj.isStrictfp()) {
    904                        throw new ClassConstraintException("Interface method '" + tostring(obj) + "' must not have"
    905                            + " any of the ACC_PRIVATE, ACC_PROTECTED, ACC_STATIC, ACC_FINAL, ACC_SYNCHRONIZED,"
    906                            + " ACC_NATIVE, ACC_ABSTRACT, ACC_STRICT modifiers set.");
    907                    }
    908                }
    909            }
    910
    911            if ((obj.getAccessFlags() & ~(Const.ACC_PUBLIC | Const.ACC_PRIVATE | Const.ACC_PROTECTED | Const.ACC_STATIC | Const.ACC_FINAL |
    912                Const.ACC_SYNCHRONIZED | Const.ACC_NATIVE | Const.ACC_ABSTRACT | Const.ACC_STRICT)) > 0) {
    913                addMessage("Method '" + tostring(obj) + "' has access flag(s) other than" + " ACC_PUBLIC, ACC_PRIVATE, ACC_PROTECTED, ACC_STATIC, ACC_FINAL,"
    914                    + " ACC_SYNCHRONIZED, ACC_NATIVE, ACC_ABSTRACT, ACC_STRICT set (ignored).");
    915            }
    916
    917            final String nameanddesc = name + sig;
    918            if (methodNamesAndDesc.contains(nameanddesc)) {
    919                throw new ClassConstraintException("No two methods (like '" + tostring(obj) + "') are allowed have same names and desciptors!");
    920            }
    921            methodNamesAndDesc.add(nameanddesc);
    922
    923            final Attribute[] atts = obj.getAttributes();
    924            int numCodeAtts = 0;
    925            for (final Attribute att : atts) {
    926                if (!(att instanceof Code) && !(att instanceof ExceptionTable) && !(att instanceof Synthetic) && !(att instanceof Deprecated)) {
    927                    addMessage("Attribute '" + tostring(att) + "' as an attribute of Method '" + tostring(obj) + "' is unknown and will therefore be ignored.");
    928                }
    929                if (!(att instanceof Code) && !(att instanceof ExceptionTable)) {
    930                    addMessage("Attribute '" + tostring(att) + "' as an attribute of Method '" + tostring(obj)
    931                        + "' is neither Code nor Exceptions and is therefore only of use for debuggers and such.");
    932                }
    933                if (att instanceof Code && (obj.isNative() || obj.isAbstract())) {
    934                    throw new ClassConstraintException(
    935                        "Native or abstract methods like '" + tostring(obj) + "' must not have a Code attribute like '" + tostring(att) + "'."); // vmspec2
    936                                                                                                                                                 // page120,
    937                                                                                                                                                 // 4.7.3
    938                }
    939                if (att instanceof Code) {
    940                    numCodeAtts++;
    941                }
    942            }
    943            if (!obj.isNative() && !obj.isAbstract() && numCodeAtts != 1) {
    944                throw new ClassConstraintException(
    945                    "Non-native, non-abstract methods like '" + tostring(obj) + "' must have exactly one Code attribute (found: " + numCodeAtts + ").");
    946            }
    947        }
    948
    949        ///////////////////////////////////////////////////////
    950        // ClassFile-structure-ATTRIBUTES (vmspec2 4.1, 4.7) //
    951        ///////////////////////////////////////////////////////
    952        @Override
    953        public void visitSourceFile(final SourceFile obj) {// vmspec2 4.7.7
    954
    955            // zero or one SourceFile attr per ClassFile: see visitJavaClass()
    956
    957            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    958
    959            final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    960            if (!name.equals("SourceFile")) {
    961                throw new ClassConstraintException("The SourceFile attribute '" + tostring(obj) + "' is not correctly named 'SourceFile' but '" + name + "'.");
    962            }
    963
    964            checkIndex(obj, obj.getSourceFileIndex(), CONST_Utf8);
    965
    966            final String sourceFileName = ((ConstantUtf8) cp.getConstant(obj.getSourceFileIndex())).getBytes(); // ==obj.getSourceFileName() ?
    967            final String sourceFileNameLc = sourceFileName.toLowerCase(Locale.ENGLISH);
    968
    969            if (sourceFileName.indexOf('/') != -1 || sourceFileName.indexOf('\\') != -1 || sourceFileName.indexOf(':') != -1
    970                || sourceFileNameLc.lastIndexOf(".java") == -1) {
    971                addMessage("SourceFile attribute '" + tostring(obj)
    972                    + "' has a funny name: remember not to confuse certain parsers working on javap's output. Also, this name ('" + sourceFileName
    973                    + "') is considered an unqualified (simple) file name only.");
    974            }
    975        }
    976
    977        @Override
    978        public void visitSynthetic(final Synthetic obj) {// vmspec2 4.7.6
    979            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    980            final String name = ((ConstantUtf8) cp.getConstant(obj.getNameIndex())).getBytes();
    981            if (!name.equals("Synthetic")) {
    982                throw new ClassConstraintException("The Synthetic attribute '" + tostring(obj) + "' is not correctly named 'Synthetic' but '" + name + "'.");
    983            }
    984        }
    985
    986        ////////////////////////////////////////////////////
    987        // MISC-structure-ATTRIBUTES (vmspec2 4.7.1, 4.7) //
    988        ////////////////////////////////////////////////////
    989        @Override
    990        public void visitUnknown(final Unknown obj) {// vmspec2 4.7.1
    991            // Represents an unknown attribute.
    992            checkIndex(obj, obj.getNameIndex(), CONST_Utf8);
    993
    994            // Maybe only misnamed? Give a (warning) message.
    995            addMessage("Unknown attribute '" + tostring(obj) + "'. This attribute is not known in any context!");
    996        }
    997    }
    998
    999    /**
    1000     * A Visitor class that ensures the ConstantCP-subclassed entries of the constant pool are valid. <B>Precondition:
    1001     * index-style cross referencing in the constant pool must be valid.</B>
    1002     *
    1003     * @see #constantPoolEntriesSatisfyStaticConstraints()
    1004     * @see org.apache.bcel.classfile.ConstantCP
    1005     */
    1006    private final class FAMRAV_Visitor extends EmptyVisitor {
    1007        private final ConstantPool cp; // ==jc.getConstantPool() -- only here to save typing work.
    1008
    1009        private FAMRAV_Visitor(final JavaClass jc) {
    1010            this.cp = jc.getConstantPool();
    1011        }
    1012
    1013        @Override
    1014        public void visitConstantFieldref(final ConstantFieldref obj) {
    1015            if (obj.getTag() != Const.CONSTANT_Fieldref) {
    1016                throw new ClassConstraintException("ConstantFieldref '" + tostring(obj) + "' has wrong tag!");
    1017            }
    1018            final int nameAndTypeIndex = obj.getNameAndTypeIndex();
    1019            final ConstantNameAndType cnat = (ConstantNameAndType) cp.getConstant(nameAndTypeIndex);
    1020            final String name = ((ConstantUtf8) cp.getConstant(cnat.getNameIndex())).getBytes(); // Field or Method name
    1021            if (!validFieldName(name)) {
    1022                throw new ClassConstraintException("Invalid field name '" + name + "' referenced by '" + tostring(obj) + "'.");
    1023            }
    1024
    1025            final int classIndex = obj.getClassIndex();
    1026            final ConstantClass cc = (ConstantClass) cp.getConstant(classIndex);
    1027            final String className = ((ConstantUtf8) cp.getConstant(cc.getNameIndex())).getBytes(); // Class Name in internal form
    1028            if (!validClassName(className)) {
    1029                throw new ClassConstraintException("Illegal class name '" + className + "' used by '" + tostring(obj) + "'.");
    1030            }
    1031
    1032            final String sig = ((ConstantUtf8) cp.getConstant(cnat.getSignatureIndex())).getBytes(); // Field or Method sig.(=descriptor)
    1033
    1034            try {
    1035                Type.getType(sig); /* Don't need the return value */
    1036            } catch (final ClassFormatException cfe) {
    1037                throw new ClassConstraintException("Illegal descriptor (==signature) '" + sig + "' used by '" + tostring(obj) + "'.", cfe);
    1038            }
    1039        }
    1040
    1041        @Override
    1042        public void visitConstantInterfaceMethodref(final ConstantInterfaceMethodref obj) {
    1043            if (obj.getTag() != Const.CONSTANT_InterfaceMethodref) {
    1044                throw new ClassConstraintException("ConstantInterfaceMethodref '" + tostring(obj) + "' has wrong tag!");
    1045            }
    1046            final int nameAndTypeIndex = obj.getNameAndTypeIndex();
    1047            final ConstantNameAndType cnat = (ConstantNameAndType) cp.getConstant(nameAndTypeIndex);
    1048            final String name = ((ConstantUtf8) cp.getConstant(cnat.getNameIndex())).getBytes(); // Field or Method name
    1049            if (!validInterfaceMethodName(name)) {
    1050                throw new ClassConstraintException("Invalid (interface) method name '" + name + "' referenced by '" + tostring(obj) + "'.");
    1051            }
    1052
    1053            final int classIndex = obj.getClassIndex();
    1054            final ConstantClass cc = (ConstantClass) cp.getConstant(classIndex);
    1055            final String className = ((ConstantUtf8) cp.getConstant(cc.getNameIndex())).getBytes(); // Class Name in internal form
    1056            if (!validClassName(className)) {
    1057                throw new ClassConstraintException("Illegal class name '" + className + "' used by '" + tostring(obj) + "'.");
    1058            }
    1059
    1060            final String sig = ((ConstantUtf8) cp.getConstant(cnat.getSignatureIndex())).getBytes(); // Field or Method sig.(=descriptor)
    1061
    1062            try {
    1063                final Type t = Type.getReturnType(sig);
    1064                if (name.equals(Const.STATIC_INITIALIZER_NAME) && t != Type.VOID) {
    1065                    addMessage("Class or interface initialization method '" + Const.STATIC_INITIALIZER_NAME + "' usually has VOID return type instead of '" + t
    1066                        + "'. Note this is really not a requirement of The Java Virtual Machine Specification, Second Edition.");
    1067                }
    1068            } catch (final ClassFormatException cfe) {
    1069                throw new ClassConstraintException("Illegal descriptor (==signature) '" + sig + "' used by '" + tostring(obj) + "'.", cfe);
    1070            }
    1071
    1072        }
    1073
    1074        @Override
    1075        public void visitConstantMethodref(final ConstantMethodref obj) {
    1076            if (obj.getTag() != Const.CONSTANT_Methodref) {
    1077                throw new ClassConstraintException("ConstantMethodref '" + tostring(obj) + "' has wrong tag!");
    1078            }
    1079            final int nameAndTypeIndex = obj.getNameAndTypeIndex();
    1080            final ConstantNameAndType cnat = (ConstantNameAndType) cp.getConstant(nameAndTypeIndex);
    1081            final String name = ((ConstantUtf8) cp.getConstant(cnat.getNameIndex())).getBytes(); // Field or Method name
    1082            if (!validClassMethodName(name)) {
    1083                throw new ClassConstraintException("Invalid (non-interface) method name '" + name + "' referenced by '" + tostring(obj) + "'.");
    1084            }
    1085
    1086            final int classIndex = obj.getClassIndex();
    1087            final ConstantClass cc = (ConstantClass) cp.getConstant(classIndex);
    1088            final String className = ((ConstantUtf8) cp.getConstant(cc.getNameIndex())).getBytes(); // Class Name in internal form
    1089            if (!validClassName(className)) {
    1090                throw new ClassConstraintException("Illegal class name '" + className + "' used by '" + tostring(obj) + "'.");
    1091            }
    1092
    1093            final String sig = ((ConstantUtf8) cp.getConstant(cnat.getSignatureIndex())).getBytes(); // Field or Method sig.(=descriptor)
    1094
    1095            try {
    1096                final Type t = Type.getReturnType(sig);
    1097                if (name.equals(Const.CONSTRUCTOR_NAME) && t != Type.VOID) {
    1098                    throw new ClassConstraintException("Instance initialization method must have VOID return type.");
    1099                }
    1100            } catch (final ClassFormatException cfe) {
    1101                throw new ClassConstraintException("Illegal descriptor (==signature) '" + sig + "' used by '" + tostring(obj) + "'.", cfe);
    1102            }
    1103        }
    1104
    1105    }
    1106
    1107    /**
    1108     * This class serves for finding out if a given JavaClass' ConstantPool references an Inner Class. The Java Virtual
    1109     * Machine Specification, Second Edition is not very precise about when an "InnerClasses" attribute has to appear.
    1110     * However, it states that there has to be exactly one InnerClasses attribute in the ClassFile structure if the constant
    1111     * pool of a class or interface refers to any class or interface "that is not a member of a package". Sun does not mean
    1112     * "member of the default package". In "Inner Classes Specification" they point out how a "bytecode name" is derived so
    1113     * one has to deduce what a class name of a class "that is not a member of a package" looks like: there is at least one
    1114     * character in the byte- code name that cannot be part of a legal Java Language Class name (and not equal to '/'). This
    1115     * assumption is wrong as the delimiter is '$' for which Character.isJavaIdentifierPart() == true. Hence, you really run
    1116     * into trouble if you have a toplevel class called "A$XXX" and another toplevel class called "A" with in inner class
    1117     * called "XXX". JustIce cannot repair this; please note that existing verifiers at this time even fail to detect
    1118     * missing InnerClasses attributes in pass 2.
    1119     */
    1120    private static class InnerClassDetector extends EmptyVisitor {
    1121        private boolean hasInnerClass;
    1122        private final JavaClass jc;
    1123        private final ConstantPool cp;
    1124
    1125        /** Constructs an InnerClassDetector working on the JavaClass _jc. */
    1126        public InnerClassDetector(final JavaClass javaClass) {
    1127            this.jc = javaClass;
    1128            this.cp = jc.getConstantPool();
    1129            new DescendingVisitor(jc, this).visit();
    1130        }
    1131
    1132        /**
    1133         * Returns if the JavaClass this InnerClassDetector is working on has an Inner Class reference in its constant pool.
    1134         *
    1135         * @return Whether this InnerClassDetector is working on has an Inner Class reference in its constant pool.
    1136         */
    1137        public boolean innerClassReferenced() {
    1138            return hasInnerClass;
    1139        }
    1140
    1141        /** This method casually visits ConstantClass references. */
    1142        @Override
    1143        public void visitConstantClass(final ConstantClass obj) {
    1144            final Constant c = cp.getConstant(obj.getNameIndex());
    1145            if (c instanceof ConstantUtf8) { // Ignore the case where it's not a ConstantUtf8 here, we'll find out later.
    1146                final String className = ((ConstantUtf8) c).getBytes();
    1147                if (className.startsWith(jc.getClassName().replace('.', '/') + "$")) {
    1148                    hasInnerClass = true;
    1149                }
    1150            }
    1151        }
    1152    }
    1153
    1154    /**
    1155     * This method is here to save typing work and improve code readability.
    1156     */
    1157    private static String tostring(final Node n) {
    1158        return new StringRepresentation(n).toString();
    1159    }
    1160
    1161    /**
    1162     * This method returns true if and only if the supplied String represents a valid method name that may be referenced by
    1163     * ConstantMethodref objects.
    1164     */
    1165    private static boolean validClassMethodName(final String name) {
    1166        return validMethodName(name, false);
    1167    }
    1168
    1169    /**
    1170     * This method returns true if and only if the supplied String represents a valid Java class name.
    1171     */
    1172    private static boolean validClassName(final String name) {
    1173        /*
    1174         * TODO: implement. Are there any restrictions?
    1175         */
    1176        Objects.requireNonNull(name, "name");
    1177        return true;
    1178    }
    1179
    1180    /**
    1181     * This method returns true if and only if the supplied String represents a valid Java field name.
    1182     */
    1183    private static boolean validFieldName(final String name) {
    1184        // vmspec2 2.7, vmspec2 2.2
    1185        return validJavaIdentifier(name);
    1186    }
    1187
    1188    /**
    1189     * This method returns true if and only if the supplied String represents a valid Java interface method name that may be
    1190     * referenced by ConstantInterfaceMethodref objects.
    1191     */
    1192    private static boolean validInterfaceMethodName(final String name) {
    1193        // I guess we should assume special names forbidden here.
    1194        if (name.startsWith("<")) {
    1195            return false;
    1196        }
    1197        return validJavaLangMethodName(name);
    1198    }
    1199
    1200    /**
    1201     * This method returns true if and only if the supplied String represents a valid Java identifier (so-called simple or
    1202     * unqualified name).
    1203     */
    1204    private static boolean validJavaIdentifier(final String name) {
    1205        // vmspec2 2.7, vmspec2 2.2
    1206        if (name.isEmpty() || !Character.isJavaIdentifierStart(name.charAt(0))) {
    1207            return false;
    1208        }
    1209
    1210        for (int i = 1; i < name.length(); i++) {
    1211            if (!Character.isJavaIdentifierPart(name.charAt(i))) {
    1212                return false;
    1213            }
    1214        }
    1215        return true;
    1216    }
    1217
    1218    /**
    1219     * This method returns true if and only if the supplied String represents a valid Java programming language method name
    1220     * stored as a simple (non-qualified) name. Conforming to: The Java Virtual Machine Specification, Second Edition,
    1221     * �2.7, �2.7.1, �2.2.
    1222     */
    1223    private static boolean validJavaLangMethodName(final String name) {
    1224        return validJavaIdentifier(name);
    1225    }
    1226
    1227    /**
    1228     * This method returns true if and only if the supplied String represents a valid method name. This is basically the
    1229     * same as a valid identifier name in the Java programming language, but the special name for the instance
    1230     * initialization method is allowed and the special name for the class/interface initialization method may be allowed.
    1231     */
    1232    private static boolean validMethodName(final String name, final boolean allowStaticInit) {
    1233        if (validJavaLangMethodName(name)) {
    1234            return true;
    1235        }
    1236
    1237        if (allowStaticInit) {
    1238            return name.equals(Const.CONSTRUCTOR_NAME) || name.equals(Const.STATIC_INITIALIZER_NAME);
    1239        }
    1240        return name.equals(Const.CONSTRUCTOR_NAME);
    1241    }
    1242
    1243    /**
    1244     * The LocalVariableInfo instances used by Pass3bVerifier. localVariablesInfos[i] denotes the information for the local
    1245     * variables of method number i in the JavaClass this verifier operates on.
    1246     */
    1247    private LocalVariablesInfo[] localVariablesInfos;
    1248    /** The Verifier that created this. */
    1249    private final Verifier myOwner;
    1250
    1251    /**
    1252     * Should only be instantiated by a Verifier.
    1253     *
    1254     * @see Verifier
    1255     */
    1256    public Pass2Verifier(final Verifier owner) {
    1257        myOwner = owner;
    1258    }
    1259
    1260    /**
    1261     * Ensures that the constant pool entries satisfy the static constraints as described in The Java Virtual Machine
    1262     * Specification, 2nd Edition.
    1263     *
    1264     * @throws ClassConstraintException otherwise.
    1265     */
    1266    private void constantPoolEntriesSatisfyStaticConstraints() {
    1267        try {
    1268            // Most of the consistency is handled internally by BCEL; here
    1269            // we only have to verify if the indices of the constants point
    1270            // to constants of the appropriate type and such.
    1271            final JavaClass jc = Repository.lookupClass(myOwner.getClassName());
    1272            new CPESSC_Visitor(jc); // constructor implicitly traverses jc
    1273
    1274        } catch (final ClassNotFoundException e) {
    1275            // FIXME: this might not be the best way to handle missing classes.
    1276            throw new AssertionViolatedException("Missing class: " + e, e);
    1277        }
    1278    }
    1279
    1280    /**
    1281     * Pass 2 is the pass where static properties of the class file are checked without looking into "Code" arrays of
    1282     * methods. This verification pass is usually invoked when a class is resolved; and it may be possible that this
    1283     * verification pass has to load in other classes such as superclasses or implemented interfaces. Therefore, Pass 1 is
    1284     * run on them.<BR>
    1285     * Note that most referenced classes are <B>not</B> loaded in for verification or for an existance check by this pass;
    1286     * only the syntactical correctness of their names and descriptors (a.k.a. signatures) is checked.<BR>
    1287     * Very few checks that conceptually belong here are delayed until pass 3a in JustIce. JustIce does not only check for
    1288     * syntactical correctness but also for semantical sanity - therefore it needs access to the "Code" array of methods in
    1289     * a few cases. Please see the pass 3a documentation, too.
    1290     *
    1291     * @see Pass3aVerifier
    1292     */
    1293    @Override
    1294    public VerificationResult do_verify() {
    1295        try {
    1296            final VerificationResult vr1 = myOwner.doPass1();
    1297            if (vr1.equals(VerificationResult.VR_OK)) {
    1298
    1299                // For every method, we could have information about the local variables out of LocalVariableTable attributes of
    1300                // the Code attributes.
    1301                localVariablesInfos = new LocalVariablesInfo[Repository.lookupClass(myOwner.getClassName()).getMethods().length];
    1302
    1303                VerificationResult vr = VerificationResult.VR_OK; // default.
    1304                try {
    1305                    constantPoolEntriesSatisfyStaticConstraints();
    1306                    fieldAndMethodRefsAreValid();
    1307                    everyClassHasAnAccessibleSuperclass();
    1308                    finalMethodsAreNotOverridden();
    1309                } catch (final ClassConstraintException cce) {
    1310                    vr = new VerificationResult(VerificationResult.VERIFIED_REJECTED, cce.getMessage());
    1311                }
    1312                return vr;
    1313            }
    1314            return VerificationResult.VR_NOTYET;
    1315
    1316        } catch (final ClassNotFoundException e) {
    1317            // FIXME: this might not be the best way to handle missing classes.
    1318            throw new AssertionViolatedException("Missing class: " + e, e);
    1319        }
    1320    }
    1321
    1322    /**
    1323     * Ensures that every class has a super class and that <B>final</B> classes are not subclassed. This means, the class
    1324     * this Pass2Verifier operates on has proper super classes (transitively) up to java.lang.Object. The reason for really
    1325     * loading (and Pass1-verifying) all of those classes here is that we need them in Pass2 anyway to verify no final
    1326     * methods are overridden (that could be declared anywhere in the ancestor hierarchy).
    1327     *
    1328     * @throws ClassConstraintException otherwise.
    1329     */
    1330    private void everyClassHasAnAccessibleSuperclass() {
    1331        try {
    1332            final Set<String> hs = new HashSet<>(); // save class names to detect circular inheritance
    1333            JavaClass jc = Repository.lookupClass(myOwner.getClassName());
    1334            int supidx = -1;
    1335
    1336            while (supidx != 0) {
    1337                supidx = jc.getSuperclassNameIndex();
    1338
    1339                if (supidx == 0) {
    1340                    if (jc != Repository.lookupClass(Type.OBJECT.getClassName())) {
    1341                        throw new ClassConstraintException(
    1342                            "Superclass of '" + jc.getClassName() + "' missing but not " + Type.OBJECT.getClassName() + " itself!");
    1343                    }
    1344                } else {
    1345                    final String supername = jc.getSuperclassName();
    1346                    if (!hs.add(supername)) { // If supername already is in the list
    1347                        throw new ClassConstraintException("Circular superclass hierarchy detected.");
    1348                    }
    1349                    final Verifier v = VerifierFactory.getVerifier(supername);
    1350                    final VerificationResult vr = v.doPass1();
    1351
    1352                    if (vr != VerificationResult.VR_OK) {
    1353                        throw new ClassConstraintException("Could not load in ancestor class '" + supername + "'.");
    1354                    }
    1355                    jc = Repository.lookupClass(supername);
    1356
    1357                    if (jc.isFinal()) {
    1358                        throw new ClassConstraintException(
    1359                            "Ancestor class '" + supername + "' has the FINAL access modifier and must therefore not be subclassed.");
    1360                    }
    1361                }
    1362            }
    1363
    1364        } catch (final ClassNotFoundException e) {
    1365            // FIXME: this might not be the best way to handle missing classes.
    1366            throw new AssertionViolatedException("Missing class: " + e, e);
    1367        }
    1368    }
    1369
    1370    /**
    1371     * Ensures that the ConstantCP-subclassed entries of the constant pool are valid. According to "Yellin: Low Level
    1372     * Security in Java", this method does not verify the existence of referenced entities (such as classes) but only the
    1373     * formal correctness (such as well-formed signatures). The visitXXX() methods throw ClassConstraintException instances
    1374     * otherwise. <B>Precondition: index-style cross referencing in the constant pool must be valid. Simply invoke
    1375     * constant_pool_entries_satisfy_static_constraints() before.</B>
    1376     *
    1377     * @throws ClassConstraintException otherwise.
    1378     * @see #constantPoolEntriesSatisfyStaticConstraints()
    1379     */
    1380    private void fieldAndMethodRefsAreValid() {
    1381        try {
    1382            final JavaClass jc = Repository.lookupClass(myOwner.getClassName());
    1383            final DescendingVisitor v = new DescendingVisitor(jc, new FAMRAV_Visitor(jc));
    1384            v.visit();
    1385
    1386        } catch (final ClassNotFoundException e) {
    1387            // FIXME: this might not be the best way to handle missing classes.
    1388            throw new AssertionViolatedException("Missing class: " + e, e);
    1389        }
    1390    }
    1391
    1392    /**
    1393     * Ensures that <B>final</B> methods are not overridden. <B>Precondition to run this method:
    1394     * constant_pool_entries_satisfy_static_constraints() and every_class_has_an_accessible_superclass() have to be invoked
    1395     * before (in that order).</B>
    1396     *
    1397     * @throws ClassConstraintException otherwise.
    1398     * @see #constantPoolEntriesSatisfyStaticConstraints()
    1399     * @see #everyClassHasAnAccessibleSuperclass()
    1400     */
    1401    private void finalMethodsAreNotOverridden() {
    1402        try {
    1403            final Map<String, String> map = new HashMap<>();
    1404            JavaClass jc = Repository.lookupClass(myOwner.getClassName());
    1405
    1406            int supidx = -1;
    1407            while (supidx != 0) {
    1408                supidx = jc.getSuperclassNameIndex();
    1409
    1410                final Method[] methods = jc.getMethods();
    1411                for (final Method method : methods) {
    1412                    final String nameAndSig = method.getName() + method.getSignature();
    1413
    1414                    if (map.containsKey(nameAndSig)) {
    1415                        if (method.isFinal()) {
    1416                            if (!method.isPrivate()) {
    1417                                throw new ClassConstraintException("Method '" + nameAndSig + "' in class '" + map.get(nameAndSig)
    1418                                    + "' overrides the final (not-overridable) definition in class '" + jc.getClassName() + "'.");
    1419                            }
    1420                            addMessage("Method '" + nameAndSig + "' in class '" + map.get(nameAndSig)
    1421                                + "' overrides the final (not-overridable) definition in class '" + jc.getClassName()
    1422                                + "'. This is okay, as the original definition was private; however this constraint leverage"
    1423                                + " was introduced by JLS 8.4.6 (not vmspec2) and the behavior of the Sun verifiers.");
    1424                        } else if (!method.isStatic()) { // static methods don't inherit
    1425                            map.put(nameAndSig, jc.getClassName());
    1426                        }
    1427                    } else if (!method.isStatic()) { // static methods don't inherit
    1428                        map.put(nameAndSig, jc.getClassName());
    1429                    }
    1430                }
    1431
    1432                jc = Repository.lookupClass(jc.getSuperclassName());
    1433                // Well, for OBJECT this returns OBJECT so it works (could return anything but must not throw an Exception).
    1434            }
    1435
    1436        } catch (final ClassNotFoundException e) {
    1437            // FIXME: this might not be the best way to handle missing classes.
    1438            throw new AssertionViolatedException("Missing class: " + e, e);
    1439        }
    1440
    1441    }
    1442
    1443    /**
    1444     * Returns a LocalVariablesInfo object containing information about the usage of the local variables in the Code
    1445     * attribute of the said method or <B>null</B> if the class file this Pass2Verifier operates on could not be
    1446     * pass-2-verified correctly. The method number method_nr is the method you get using
    1447     * <B>Repository.lookupClass(myOwner.getClassname()).getMethods()[method_nr];</B>. You should not add own information.
    1448     * Leave that to JustIce.
    1449     */
    1450    public LocalVariablesInfo getLocalVariablesInfo(final int methodNr) {
    1451        if (this.verify() != VerificationResult.VR_OK) {
    1452            return null; // It's cached, don't worry.
    1453        }
    1454        if (methodNr < 0 || methodNr >= localVariablesInfos.length) {
    1455            throw new AssertionViolatedException("Method number out of range.");
    1456        }
    1457        return localVariablesInfos[methodNr];
    1458    }
    1459}