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