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 import org.apache.bcel.util.Args;
27 import org.apache.commons.lang3.ArrayUtils;
28
29 /**
30 * This class represents the table of exceptions that are thrown by a method. This attribute may be used once per
31 * method. The name of this class is <em>ExceptionTable</em> for historical reasons; The Java Virtual Machine
32 * Specification, Second Edition defines this attribute using the name <em>Exceptions</em> (which is inconsistent with
33 * the other classes).
34 *
35 * <pre>
36 * Exceptions_attribute {
37 * u2 attribute_name_index;
38 * u4 attribute_length;
39 * u2 number_of_exceptions;
40 * u2 exception_index_table[number_of_exceptions];
41 * }
42 * </pre>
43 * @see Code
44 */
45 public final class ExceptionTable extends Attribute {
46
47 private int[] exceptionIndexTable; // constant pool
48
49 /**
50 * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
51 * physical copy.
52 *
53 * @param c Source to copy.
54 */
55 public ExceptionTable(final ExceptionTable c) {
56 this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
57 }
58
59 /**
60 * Constructs object from input stream.
61 *
62 * @param nameIndex Index in constant pool
63 * @param length Content length in bytes
64 * @param input Input stream
65 * @param constantPool Array of constants
66 * @throws IOException if an I/O error occurs.
67 */
68 ExceptionTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
69 this(nameIndex, length, (int[]) null, constantPool);
70 final int exceptionCount = input.readUnsignedShort();
71 exceptionIndexTable = new int[exceptionCount];
72 for (int i = 0; i < exceptionCount; i++) {
73 exceptionIndexTable[i] = input.readUnsignedShort();
74 }
75 }
76
77 /**
78 * @param nameIndex Index in constant pool
79 * @param length Content length in bytes
80 * @param exceptionIndexTable Table of indices in constant pool
81 * @param constantPool Array of constants
82 */
83 public ExceptionTable(final int nameIndex, final int length, final int[] exceptionIndexTable, final ConstantPool constantPool) {
84 super(Const.ATTR_EXCEPTIONS, nameIndex, length, constantPool);
85 this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
86 Args.requireU2(this.exceptionIndexTable.length, "exceptionIndexTable.length");
87 }
88
89 /**
90 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
91 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
92 *
93 * @param v Visitor object
94 */
95 @Override
96 public void accept(final Visitor v) {
97 v.visitExceptionTable(this);
98 }
99
100 /**
101 * @return deep copy of this attribute
102 */
103 @Override
104 public Attribute copy(final ConstantPool constantPool) {
105 final ExceptionTable c = (ExceptionTable) clone();
106 if (exceptionIndexTable != null) {
107 c.exceptionIndexTable = exceptionIndexTable.clone();
108 }
109 c.setConstantPool(constantPool);
110 return c;
111 }
112
113 /**
114 * Dump exceptions attribute to file stream in binary format.
115 *
116 * @param file Output file stream
117 * @throws IOException if an I/O error occurs.
118 */
119 @Override
120 public void dump(final DataOutputStream file) throws IOException {
121 super.dump(file);
122 file.writeShort(exceptionIndexTable.length);
123 for (final int index : exceptionIndexTable) {
124 file.writeShort(index);
125 }
126 }
127
128 /**
129 * @return Array of indices into constant pool of thrown exceptions.
130 */
131 public int[] getExceptionIndexTable() {
132 return exceptionIndexTable;
133 }
134
135 /**
136 * @return class names of thrown exceptions
137 */
138 public String[] getExceptionNames() {
139 final String[] names = new String[exceptionIndexTable.length];
140 Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class)));
141 return names;
142 }
143
144 /**
145 * @return Length of exception table.
146 */
147 public int getNumberOfExceptions() {
148 return exceptionIndexTable == null ? 0 : exceptionIndexTable.length;
149 }
150
151 /**
152 * @param exceptionIndexTable the list of exception indexes Also redefines number_of_exceptions according to table
153 * length.
154 */
155 public void setExceptionIndexTable(final int[] exceptionIndexTable) {
156 this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
157 }
158
159 /**
160 * @return String representation, i.e., a list of thrown exceptions.
161 */
162 @Override
163 public String toString() {
164 final StringBuilder buf = new StringBuilder();
165 String str;
166 buf.append("Exceptions: ");
167 for (int i = 0; i < exceptionIndexTable.length; i++) {
168 str = super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class);
169 buf.append(Utility.compactClassName(str, false));
170 if (i < exceptionIndexTable.length - 1) {
171 buf.append(", ");
172 }
173 }
174 return buf.toString();
175 }
176 }