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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   */
17  
18  package org.apache.bcel.classfile;
19  
20  import java.io.DataInput;
21  import java.io.DataOutputStream;
22  import java.io.IOException;
23  import java.util.Arrays;
24  
25  import org.apache.bcel.Const;
26  
27  /**
28   * This class represents a stack map entry recording the types of local variables and the of stack items at a given
29   * byte code offset. See CLDC specification 5.3.1.2.
30   *
31   * See also https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.4
32   *
33   * <pre>
34   * union stack_map_frame {
35   *   same_frame;
36   *   same_locals_1_stack_item_frame;
37   *   same_locals_1_stack_item_frame_extended;
38   *   chop_frame;
39   *   same_frame_extended;
40   *   append_frame;
41   *   full_frame;
42   * }
43   * </pre>
44   * @see StackMap
45   * @see StackMapType
46   */
47  public final class StackMapEntry implements Node, Cloneable {
48  
49      static final StackMapEntry[] EMPTY_ARRAY = {};
50  
51      private int frameType;
52      private int byteCodeOffset;
53      private StackMapType[] typesOfLocals;
54      private StackMapType[] typesOfStackItems;
55      private ConstantPool constantPool;
56  
57      /**
58       * Constructs object from input stream.
59       *
60       * @param dataInput Input stream
61       * @throws IOException if an I/O error occurs.
62       */
63      StackMapEntry(final DataInput dataInput, final ConstantPool constantPool) throws IOException {
64          this(dataInput.readByte() & 0xFF, -1, null, null, constantPool);
65  
66          if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
67              byteCodeOffset = frameType - Const.SAME_FRAME;
68          } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
69              byteCodeOffset = frameType - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
70              typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
71          } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
72              byteCodeOffset = dataInput.readUnsignedShort();
73              typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
74          } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
75              byteCodeOffset = dataInput.readUnsignedShort();
76          } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
77              byteCodeOffset = dataInput.readUnsignedShort();
78              final int numberOfLocals = frameType - 251;
79              typesOfLocals = new StackMapType[numberOfLocals];
80              for (int i = 0; i < numberOfLocals; i++) {
81                  typesOfLocals[i] = new StackMapType(dataInput, constantPool);
82              }
83          } else if (frameType == Const.FULL_FRAME) {
84              byteCodeOffset = dataInput.readUnsignedShort();
85              final int numberOfLocals = dataInput.readUnsignedShort();
86              typesOfLocals = new StackMapType[numberOfLocals];
87              for (int i = 0; i < numberOfLocals; i++) {
88                  typesOfLocals[i] = new StackMapType(dataInput, constantPool);
89              }
90              final int numberOfStackItems = dataInput.readUnsignedShort();
91              typesOfStackItems = new StackMapType[numberOfStackItems];
92              for (int i = 0; i < numberOfStackItems; i++) {
93                  typesOfStackItems[i] = new StackMapType(dataInput, constantPool);
94              }
95          } else {
96              /* Can't happen */
97              throw new ClassFormatException("Invalid frame type found while parsing stack map table: " + frameType);
98          }
99      }
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 }