    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019
    020package org.apache.bcel.classfile;
    021
    022import java.io.DataInput;
    023import java.io.DataOutputStream;
    024import java.io.IOException;
    025import java.util.Arrays;
    026
    027import org.apache.bcel.Const;
    028
    029/**
    030 * This class represents a stack map entry recording the types of local variables and the of stack items at a given
    031 * byte code offset. See CLDC specification 5.3.1.2.
    032 *
    033 * See also https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.4
    034 *
    035 * <pre>
    036 * union stack_map_frame {
    037 *   same_frame;
    038 *   same_locals_1_stack_item_frame;
    039 *   same_locals_1_stack_item_frame_extended;
    040 *   chop_frame;
    041 *   same_frame_extended;
    042 *   append_frame;
    043 *   full_frame;
    044 * }
    045 * </pre>
    046 * @see StackMap
    047 * @see StackMapType
    048 */
    049public final class StackMapEntry implements Node, Cloneable {
    050
    051    static final StackMapEntry[] EMPTY_ARRAY = {};
    052
    053    private int frameType;
    054    private int byteCodeOffset;
    055    private StackMapType[] typesOfLocals;
    056    private StackMapType[] typesOfStackItems;
    057    private ConstantPool constantPool;
    058
    059    /**
    060     * Constructs object from input stream.
    061     *
    062     * @param dataInput Input stream
    063     * @throws IOException if an I/O error occurs.
    064     */
    065    StackMapEntry(final DataInput dataInput, final ConstantPool constantPool) throws IOException {
    066        this(dataInput.readByte() & 0xFF, -1, null, null, constantPool);
    067
    068        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    069            byteCodeOffset = frameType - Const.SAME_FRAME;
    070        } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    071            byteCodeOffset = frameType - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
    072            typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
    073        } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    074            byteCodeOffset = dataInput.readUnsignedShort();
    075            typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
    076        } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
    077            byteCodeOffset = dataInput.readUnsignedShort();
    078        } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    079            byteCodeOffset = dataInput.readUnsignedShort();
    080            final int numberOfLocals = frameType - 251;
    081            typesOfLocals = new StackMapType[numberOfLocals];
    082            for (int i = 0; i < numberOfLocals; i++) {
    083                typesOfLocals[i] = new StackMapType(dataInput, constantPool);
    084            }
    085        } else if (frameType == Const.FULL_FRAME) {
    086            byteCodeOffset = dataInput.readUnsignedShort();
    087            final int numberOfLocals = dataInput.readUnsignedShort();
    088            typesOfLocals = new StackMapType[numberOfLocals];
    089            for (int i = 0; i < numberOfLocals; i++) {
    090                typesOfLocals[i] = new StackMapType(dataInput, constantPool);
    091            }
    092            final int numberOfStackItems = dataInput.readUnsignedShort();
    093            typesOfStackItems = new StackMapType[numberOfStackItems];
    094            for (int i = 0; i < numberOfStackItems; i++) {
    095                typesOfStackItems[i] = new StackMapType(dataInput, constantPool);
    096            }
    097        } else {
    098            /* Can't happen */
    099            throw new ClassFormatException("Invalid frame type found while parsing stack map table: " + frameType);
    100        }
    101    }
    102
    103    /**
    104     * DO NOT USE
    105     *
    106     * @param byteCodeOffset
    107     * @param numberOfLocals NOT USED
    108     * @param typesOfLocals array of {@link StackMapType}s of locals
    109     * @param numberOfStackItems NOT USED
    110     * @param typesOfStackItems array ot {@link StackMapType}s of stack items
    111     * @param constantPool the constant pool
    112     * @deprecated Since 6.0, use {@link #StackMapEntry(int, int, StackMapType[], StackMapType[], ConstantPool)} instead
    113     */
    114    @java.lang.Deprecated
    115    public StackMapEntry(final int byteCodeOffset, final int numberOfLocals, final StackMapType[] typesOfLocals, final int numberOfStackItems,
    116        final StackMapType[] typesOfStackItems, final ConstantPool constantPool) {
    117        this.byteCodeOffset = byteCodeOffset;
    118        this.typesOfLocals = typesOfLocals != null ? typesOfLocals : StackMapType.EMPTY_ARRAY;
    119        this.typesOfStackItems = typesOfStackItems != null ? typesOfStackItems : StackMapType.EMPTY_ARRAY;
    120        this.constantPool = constantPool;
    121        if (numberOfLocals < 0) {
    122            throw new IllegalArgumentException("numberOfLocals < 0");
    123        }
    124        if (numberOfStackItems < 0) {
    125            throw new IllegalArgumentException("numberOfStackItems < 0");
    126        }
    127    }
    128
    129    /**
    130     * Create an instance
    131     *
    132     * @param tag the frameType to use
    133     * @param byteCodeOffset
    134     * @param typesOfLocals array of {@link StackMapType}s of locals
    135     * @param typesOfStackItems array ot {@link StackMapType}s of stack items
    136     * @param constantPool the constant pool
    137     */
    138    public StackMapEntry(final int tag, final int byteCodeOffset, final StackMapType[] typesOfLocals, final StackMapType[] typesOfStackItems,
    139        final ConstantPool constantPool) {
    140        this.frameType = tag;
    141        this.byteCodeOffset = byteCodeOffset;
    142        this.typesOfLocals = typesOfLocals != null ? typesOfLocals : StackMapType.EMPTY_ARRAY;
    143        this.typesOfStackItems = typesOfStackItems != null ? typesOfStackItems : StackMapType.EMPTY_ARRAY;
    144        this.constantPool = constantPool;
    145    }
    146
    147    /**
    148     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    149     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    150     *
    151     * @param v Visitor object
    152     */
    153    @Override
    154    public void accept(final Visitor v) {
    155        v.visitStackMapEntry(this);
    156    }
    157
    158    /**
    159     * @return deep copy of this object
    160     */
    161    public StackMapEntry copy() {
    162        final StackMapEntry e;
    163        try {
    164            e = (StackMapEntry) clone();
    165        } catch (final CloneNotSupportedException ex) {
    166            throw new UnsupportedOperationException("Clone Not Supported", ex);
    167        }
    168
    169        e.typesOfLocals = new StackMapType[typesOfLocals.length];
    170        Arrays.setAll(e.typesOfLocals, i -> typesOfLocals[i].copy());
    171        e.typesOfStackItems = new StackMapType[typesOfStackItems.length];
    172        Arrays.setAll(e.typesOfStackItems, i -> typesOfStackItems[i].copy());
    173        return e;
    174    }
    175
    176    /**
    177     * Dump stack map entry
    178     *
    179     * @param file Output file stream
    180     * @throws IOException if an I/O error occurs.
    181     */
    182    public void dump(final DataOutputStream file) throws IOException {
    183        file.write(frameType);
    184        if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    185            typesOfStackItems[0].dump(file);
    186        } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    187            file.writeShort(byteCodeOffset);
    188            typesOfStackItems[0].dump(file);
    189        } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
    190            file.writeShort(byteCodeOffset);
    191        } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    192            file.writeShort(byteCodeOffset);
    193            for (final StackMapType type : typesOfLocals) {
    194                type.dump(file);
    195            }
    196        } else if (frameType == Const.FULL_FRAME) {
    197            file.writeShort(byteCodeOffset);
    198            file.writeShort(typesOfLocals.length);
    199            for (final StackMapType type : typesOfLocals) {
    200                type.dump(file);
    201            }
    202            file.writeShort(typesOfStackItems.length);
    203            for (final StackMapType type : typesOfStackItems) {
    204                type.dump(file);
    205            }
    206        } else if (!(frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX)) {
    207            /* Can't happen */
    208            throw new ClassFormatException("Invalid Stack map table tag: " + frameType);
    209        }
    210    }
    211
    212    public int getByteCodeOffset() {
    213        return byteCodeOffset;
    214    }
    215
    216    /**
    217     * @return Constant pool used by this object.
    218     */
    219    public ConstantPool getConstantPool() {
    220        return constantPool;
    221    }
    222
    223    public int getFrameType() {
    224        return frameType;
    225    }
    226
    227    /**
    228     * Calculate stack map entry size
    229     */
    230    int getMapEntrySize() {
    231        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    232            return 1;
    233        }
    234        if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    235            return 1 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
    236        }
    237        if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    238            return 3 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
    239        }
    240        if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
    241            return 3;
    242        }
    243        if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    244            int len = 3;
    245            for (final StackMapType typesOfLocal : typesOfLocals) {
    246                len += typesOfLocal.hasIndex() ? 3 : 1;
    247            }
    248            return len;
    249        }
    250        if (frameType != Const.FULL_FRAME) {
    251            throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
    252        }
    253        int len = 7;
    254        for (final StackMapType typesOfLocal : typesOfLocals) {
    255            len += typesOfLocal.hasIndex() ? 3 : 1;
    256        }
    257        for (final StackMapType typesOfStackItem : typesOfStackItems) {
    258            len += typesOfStackItem.hasIndex() ? 3 : 1;
    259        }
    260        return len;
    261    }
    262
    263    public int getNumberOfLocals() {
    264        return typesOfLocals.length;
    265    }
    266
    267    public int getNumberOfStackItems() {
    268        return typesOfStackItems.length;
    269    }
    270
    271    public StackMapType[] getTypesOfLocals() {
    272        return typesOfLocals;
    273    }
    274
    275    public StackMapType[] getTypesOfStackItems() {
    276        return typesOfStackItems;
    277    }
    278
    279    private boolean invalidFrameType(final int f) {
    280        // @formatter:off
    281        return f != Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED
    282            && !(f >= Const.CHOP_FRAME && f <= Const.CHOP_FRAME_MAX)
    283            && f != Const.SAME_FRAME_EXTENDED
    284            && !(f >= Const.APPEND_FRAME && f <= Const.APPEND_FRAME_MAX)
    285            && f != Const.FULL_FRAME;
    286        // @formatter:on
    287    }
    288
    289    public void setByteCodeOffset(final int newOffset) {
    290        if (newOffset < 0 || newOffset > 32767) {
    291            throw new IllegalArgumentException("Invalid StackMap offset: " + newOffset);
    292        }
    293
    294        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    295            if (newOffset > Const.SAME_FRAME_MAX) {
    296                frameType = Const.SAME_FRAME_EXTENDED;
    297            } else {
    298                frameType = newOffset;
    299            }
    300        } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    301            if (newOffset > Const.SAME_FRAME_MAX) {
    302                frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED;
    303            } else {
    304                frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME + newOffset;
    305            }
    306        } else if (invalidFrameType(frameType)) {
    307            throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
    308        }
    309        byteCodeOffset = newOffset;
    310    }
    311
    312    /**
    313     * @param constantPool Constant pool to be used for this object.
    314     */
    315    public void setConstantPool(final ConstantPool constantPool) {
    316        this.constantPool = constantPool;
    317    }
    318
    319    public void setFrameType(final int ft) {
    320        if (ft >= Const.SAME_FRAME && ft <= Const.SAME_FRAME_MAX) {
    321            byteCodeOffset = ft - Const.SAME_FRAME;
    322        } else if (ft >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && ft <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    323            byteCodeOffset = ft - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
    324        } else if (invalidFrameType(ft)) {
    325            throw new IllegalArgumentException("Invalid StackMap frameType");
    326        }
    327        frameType = ft;
    328    }
    329
    330    /**
    331     *
    332     * @deprecated since 6.0
    333     */
    334    @java.lang.Deprecated
    335    public void setNumberOfLocals(final int n) { // TODO unused
    336    }
    337
    338    /**
    339     *
    340     * @deprecated since 6.0
    341     */
    342    @java.lang.Deprecated
    343    public void setNumberOfStackItems(final int n) { // TODO unused
    344    }
    345
    346    public void setTypesOfLocals(final StackMapType[] types) {
    347        typesOfLocals = types != null ? types : StackMapType.EMPTY_ARRAY;
    348    }
    349
    350    public void setTypesOfStackItems(final StackMapType[] types) {
    351        typesOfStackItems = types != null ? types : StackMapType.EMPTY_ARRAY;
    352    }
    353
    354    /**
    355     * @return String representation.
    356     */
    357    @Override
    358    public String toString() {
    359        final StringBuilder buf = new StringBuilder(64);
    360        buf.append("(");
    361        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    362            buf.append("SAME");
    363        } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    364            buf.append("SAME_LOCALS_1_STACK");
    365        } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    366            buf.append("SAME_LOCALS_1_STACK_EXTENDED");
    367        } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX) {
    368            buf.append("CHOP ").append(String.valueOf(251 - frameType));
    369        } else if (frameType == Const.SAME_FRAME_EXTENDED) {
    370            buf.append("SAME_EXTENDED");
    371        } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    372            buf.append("APPEND ").append(String.valueOf(frameType - 251));
    373        } else if (frameType == Const.FULL_FRAME) {
    374            buf.append("FULL");
    375        } else {
    376            buf.append("UNKNOWN (").append(frameType).append(")");
    377        }
    378        buf.append(", offset delta=").append(byteCodeOffset);
    379        if (typesOfLocals.length > 0) {
    380            buf.append(", locals={");
    381            for (int i = 0; i < typesOfLocals.length; i++) {
    382                buf.append(typesOfLocals[i]);
    383                if (i < typesOfLocals.length - 1) {
    384                    buf.append(", ");
    385                }
    386            }
    387            buf.append("}");
    388        }
    389        if (typesOfStackItems.length > 0) {
    390            buf.append(", stack items={");
    391            for (int i = 0; i < typesOfStackItems.length; i++) {
    392                buf.append(typesOfStackItems[i]);
    393                if (i < typesOfStackItems.length - 1) {
    394                    buf.append(", ");
    395                }
    396            }
    397            buf.append("}");
    398        }
    399        buf.append(")");
    400        return buf.toString();
    401    }
    402
    403    /**
    404     * Update the distance (as an offset delta) from this StackMap entry to the next. Note that this might cause the
    405     * frame type to change. Note also that delta may be negative.
    406     *
    407     * @param delta offset delta
    408     */
    409    public void updateByteCodeOffset(final int delta) {
    410        setByteCodeOffset(byteCodeOffset + delta);
    411    }
    412}