1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package org.apache.bcel.classfile;
21
22 import java.io.DataInput;
23 import java.io.DataOutputStream;
24 import java.io.IOException;
25 import java.util.Arrays;
26
27 import org.apache.bcel.Const;
28 import org.apache.commons.lang3.ArrayUtils;
29
30 /**
31 * This class represents a bootstrap method attribute, that is, the bootstrap method ref, the number of bootstrap arguments
32 * and an array of the bootstrap arguments.
33 *
34 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.23"> The class File Format :
35 * The BootstrapMethods Attribute</a>
36 * @since 6.0
37 */
38 public class BootstrapMethod implements Cloneable {
39
40 static final BootstrapMethod[] EMPTY_ARRAY = {};
41
42 /** Index of the CONSTANT_MethodHandle_info structure in the constant_pool table */
43 private int bootstrapMethodRef;
44
45 /** Array of references to the constant_pool table */
46 private int[] bootstrapArguments;
47
48 /**
49 * Initialize from another object.
50 *
51 * @param c Source to copy.
52 */
53 public BootstrapMethod(final BootstrapMethod c) {
54 this(c.getBootstrapMethodRef(), c.getBootstrapArguments());
55 }
56
57 /**
58 * Constructs object from input stream.
59 *
60 * @param input Input stream.
61 * @throws IOException if an I/O error occurs.
62 */
63 BootstrapMethod(final DataInput input) throws IOException {
64 this(input.readUnsignedShort(), input.readUnsignedShort());
65
66 for (int i = 0; i < bootstrapArguments.length; i++) {
67 bootstrapArguments[i] = input.readUnsignedShort();
68 }
69 }
70
71 // helper method
72 private BootstrapMethod(final int bootstrapMethodRef, final int numBootstrapArguments) {
73 this(bootstrapMethodRef, new int[numBootstrapArguments]);
74 }
75
76 /**
77 * Constructs a BootstrapMethod.
78 *
79 * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle.
80 * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info.
81 */
82 public BootstrapMethod(final int bootstrapMethodRef, final int[] bootstrapArguments) {
83 this.bootstrapMethodRef = bootstrapMethodRef;
84 setBootstrapArguments(bootstrapArguments);
85 }
86
87 /**
88 * Creates a deep copy of this object.
89 *
90 * @return deep copy of this object.
91 */
92 public BootstrapMethod copy() {
93 try {
94 return (BootstrapMethod) clone();
95 } catch (final CloneNotSupportedException ignore) {
96 // TODO should this throw?
97 }
98 return null;
99 }
100
101 /**
102 * Dumps object to file stream in binary format.
103 *
104 * @param file Output file stream.
105 * @throws IOException if an I/O error occurs.
106 */
107 public final void dump(final DataOutputStream file) throws IOException {
108 file.writeShort(bootstrapMethodRef);
109 file.writeShort(bootstrapArguments.length);
110 for (final int bootstrapArgument : bootstrapArguments) {
111 file.writeShort(bootstrapArgument);
112 }
113 }
114
115 /**
116 * Gets the bootstrap arguments.
117 *
118 * @return int[] of bootstrap_method indices into constant_pool of CONSTANT_[type]_info.
119 */
120 public int[] getBootstrapArguments() {
121 return bootstrapArguments;
122 }
123
124 /**
125 * Gets the bootstrap method reference.
126 *
127 * @return index into constant_pool of bootstrap_method.
128 */
129 public int getBootstrapMethodRef() {
130 return bootstrapMethodRef;
131 }
132
133 /**
134 * Gets the count of number of bootstrap arguments.
135 *
136 * @return count of number of bootstrap arguments.
137 */
138 public int getNumBootstrapArguments() {
139 return bootstrapArguments.length;
140 }
141
142 /**
143 * Sets the bootstrap arguments.
144 *
145 * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info.
146 */
147 public void setBootstrapArguments(final int[] bootstrapArguments) {
148 this.bootstrapArguments = ArrayUtils.nullToEmpty(bootstrapArguments);
149 }
150
151 /**
152 * Sets the bootstrap method reference.
153 *
154 * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle.
155 */
156 public void setBootstrapMethodRef(final int bootstrapMethodRef) {
157 this.bootstrapMethodRef = bootstrapMethodRef;
158 }
159
160 /**
161 * Gets a string representation.
162 *
163 * @return String representation.
164 */
165 @Override
166 public final String toString() {
167 return "BootstrapMethod(" + bootstrapMethodRef + ", " + bootstrapArguments.length + ", " + Arrays.toString(bootstrapArguments) + ")";
168 }
169
170 /**
171 * Gets a resolved string representation.
172 *
173 * @param constantPool the constant pool.
174 * @return Resolved string representation.
175 */
176 public final String toString(final ConstantPool constantPool) {
177 final StringBuilder buf = new StringBuilder();
178 final String bootstrapMethodName = constantPool.constantToString(bootstrapMethodRef, Const.CONSTANT_MethodHandle);
179 buf.append(Utility.compactClassName(bootstrapMethodName, false));
180 final int bootstrapArgumentsLen = bootstrapArguments.length;
181 if (bootstrapArgumentsLen > 0) {
182 buf.append("\nMethod Arguments:");
183 for (int i = 0; i < bootstrapArgumentsLen; i++) {
184 buf.append("\n ").append(i).append(": ");
185 buf.append(constantPool.constantToString(constantPool.getConstant(bootstrapArguments[i])));
186 }
187 }
188 return buf.toString();
189 }
190 }