    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     * Construct 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) {
    075            byteCodeOffset = dataInput.readUnsignedShort();
    076        } else if (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        StackMapEntry e;
    163        try {
    164            e = (StackMapEntry) clone();
    165        } catch (final CloneNotSupportedException ex) {
    166            throw new Error("Clone Not Supported");
    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) {
    190            file.writeShort(byteCodeOffset);
    191        } else if (frameType == Const.SAME_FRAME_EXTENDED) {
    192            file.writeShort(byteCodeOffset);
    193        } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    194            file.writeShort(byteCodeOffset);
    195            for (final StackMapType type : typesOfLocals) {
    196                type.dump(file);
    197            }
    198        } else if (frameType == Const.FULL_FRAME) {
    199            file.writeShort(byteCodeOffset);
    200            file.writeShort(typesOfLocals.length);
    201            for (final StackMapType type : typesOfLocals) {
    202                type.dump(file);
    203            }
    204            file.writeShort(typesOfStackItems.length);
    205            for (final StackMapType type : typesOfStackItems) {
    206                type.dump(file);
    207            }
    208        } else if (!(frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX)) {
    209            /* Can't happen */
    210            throw new ClassFormatException("Invalid Stack map table tag: " + frameType);
    211        }
    212    }
    213
    214    public int getByteCodeOffset() {
    215        return byteCodeOffset;
    216    }
    217
    218    /**
    219     * @return Constant pool used by this object.
    220     */
    221    public ConstantPool getConstantPool() {
    222        return constantPool;
    223    }
    224
    225    public int getFrameType() {
    226        return frameType;
    227    }
    228
    229    /**
    230     * Calculate stack map entry size
    231     *
    232     */
    233    int getMapEntrySize() {
    234        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    235            return 1;
    236        }
    237        if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    238            return 1 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
    239        }
    240        if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    241            return 3 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
    242        }
    243        if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
    244            return 3;
    245        }
    246        if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    247            int len = 3;
    248            for (final StackMapType typesOfLocal : typesOfLocals) {
    249                len += typesOfLocal.hasIndex() ? 3 : 1;
    250            }
    251            return len;
    252        }
    253        if (frameType != Const.FULL_FRAME) {
    254            throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
    255        }
    256        int len = 7;
    257        for (final StackMapType typesOfLocal : typesOfLocals) {
    258            len += typesOfLocal.hasIndex() ? 3 : 1;
    259        }
    260        for (final StackMapType typesOfStackItem : typesOfStackItems) {
    261            len += typesOfStackItem.hasIndex() ? 3 : 1;
    262        }
    263        return len;
    264    }
    265
    266    public int getNumberOfLocals() {
    267        return typesOfLocals.length;
    268    }
    269
    270    public int getNumberOfStackItems() {
    271        return typesOfStackItems.length;
    272    }
    273
    274    public StackMapType[] getTypesOfLocals() {
    275        return typesOfLocals;
    276    }
    277
    278    public StackMapType[] getTypesOfStackItems() {
    279        return typesOfStackItems;
    280    }
    281
    282    private boolean invalidFrameType(final int f) {
    283        // @formatter:off
    284        return f != Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED
    285            && !(f >= Const.CHOP_FRAME && f <= Const.CHOP_FRAME_MAX)
    286            && f != Const.SAME_FRAME_EXTENDED
    287            && !(f >= Const.APPEND_FRAME && f <= Const.APPEND_FRAME_MAX)
    288            && f != Const.FULL_FRAME;
    289        // @formatter:on
    290    }
    291
    292    public void setByteCodeOffset(final int newOffset) {
    293        if (newOffset < 0 || newOffset > 32767) {
    294            throw new IllegalArgumentException("Invalid StackMap offset: " + newOffset);
    295        }
    296
    297        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    298            if (newOffset > Const.SAME_FRAME_MAX) {
    299                frameType = Const.SAME_FRAME_EXTENDED;
    300            } else {
    301                frameType = newOffset;
    302            }
    303        } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    304            if (newOffset > Const.SAME_FRAME_MAX) {
    305                frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED;
    306            } else {
    307                frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME + newOffset;
    308            }
    309        } else if (invalidFrameType(frameType)) {
    310            throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
    311        }
    312        byteCodeOffset = newOffset;
    313    }
    314
    315    /**
    316     * @param constantPool Constant pool to be used for this object.
    317     */
    318    public void setConstantPool(final ConstantPool constantPool) {
    319        this.constantPool = constantPool;
    320    }
    321
    322    public void setFrameType(final int ft) {
    323        if (ft >= Const.SAME_FRAME && ft <= Const.SAME_FRAME_MAX) {
    324            byteCodeOffset = ft - Const.SAME_FRAME;
    325        } else if (ft >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && ft <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    326            byteCodeOffset = ft - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
    327        } else if (invalidFrameType(ft)) {
    328            throw new IllegalArgumentException("Invalid StackMap frameType");
    329        }
    330        frameType = ft;
    331    }
    332
    333    /**
    334     *
    335     * @deprecated since 6.0
    336     */
    337    @java.lang.Deprecated
    338    public void setNumberOfLocals(final int n) { // TODO unused
    339    }
    340
    341    /**
    342     *
    343     * @deprecated since 6.0
    344     */
    345    @java.lang.Deprecated
    346    public void setNumberOfStackItems(final int n) { // TODO unused
    347    }
    348
    349    public void setTypesOfLocals(final StackMapType[] types) {
    350        typesOfLocals = types != null ? types : StackMapType.EMPTY_ARRAY;
    351    }
    352
    353    public void setTypesOfStackItems(final StackMapType[] types) {
    354        typesOfStackItems = types != null ? types : StackMapType.EMPTY_ARRAY;
    355    }
    356
    357    /**
    358     * @return String representation.
    359     */
    360    @Override
    361    public String toString() {
    362        final StringBuilder buf = new StringBuilder(64);
    363        buf.append("(");
    364        if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
    365            buf.append("SAME");
    366        } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
    367            buf.append("SAME_LOCALS_1_STACK");
    368        } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
    369            buf.append("SAME_LOCALS_1_STACK_EXTENDED");
    370        } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX) {
    371            buf.append("CHOP ").append(String.valueOf(251 - frameType));
    372        } else if (frameType == Const.SAME_FRAME_EXTENDED) {
    373            buf.append("SAME_EXTENDED");
    374        } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
    375            buf.append("APPEND ").append(String.valueOf(frameType - 251));
    376        } else if (frameType == Const.FULL_FRAME) {
    377            buf.append("FULL");
    378        } else {
    379            buf.append("UNKNOWN (").append(frameType).append(")");
    380        }
    381        buf.append(", offset delta=").append(byteCodeOffset);
    382        if (typesOfLocals.length > 0) {
    383            buf.append(", locals={");
    384            for (int i = 0; i < typesOfLocals.length; i++) {
    385                buf.append(typesOfLocals[i]);
    386                if (i < typesOfLocals.length - 1) {
    387                    buf.append(", ");
    388                }
    389            }
    390            buf.append("}");
    391        }
    392        if (typesOfStackItems.length > 0) {
    393            buf.append(", stack items={");
    394            for (int i = 0; i < typesOfStackItems.length; i++) {
    395                buf.append(typesOfStackItems[i]);
    396                if (i < typesOfStackItems.length - 1) {
    397                    buf.append(", ");
    398                }
    399            }
    400            buf.append("}");
    401        }
    402        buf.append(")");
    403        return buf.toString();
    404    }
    405
    406    /**
    407     * Update the distance (as an offset delta) from this StackMap entry to the next. Note that this might cause the
    408     * frame type to change. Note also that delta may be negative.
    409     *
    410     * @param delta offset delta
    411     */
    412    public void updateByteCodeOffset(final int delta) {
    413        setByteCodeOffset(byteCodeOffset + delta);
    414    }
    415}