1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * This file is available under and governed by the GNU General Public
27 * License version 2 only, as published by the Free Software Foundation.
28 * However, the following notice accompanied the original version of this
29 * file:
30 *
31 * ASM: a very small and fast Java bytecode manipulation framework
32 * Copyright (c) 2000-2011 INRIA, France Telecom
33 * All rights reserved.
34 *
35 * Redistribution and use in source and binary forms, with or without
36 * modification, are permitted provided that the following conditions
37 * are met:
38 * 1. Redistributions of source code must retain the above copyright
39 * notice, this list of conditions and the following disclaimer.
40 * 2. Redistributions in binary form must reproduce the above copyright
41 * notice, this list of conditions and the following disclaimer in the
42 * documentation and/or other materials provided with the distribution.
43 * 3. Neither the name of the copyright holders nor the names of its
44 * contributors may be used to endorse or promote products derived from
45 * this software without specific prior written permission.
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
48 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
51 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
52 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
53 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
54 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
55 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
56 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
57 * THE POSSIBILITY OF SUCH DAMAGE.
58 */
59 package jdk.internal.org.objectweb.asm;
60
61 /**
62 * A non standard class, field, method or code attribute.
63 *
64 * @author Eric Bruneton
65 * @author Eugene Kuleshov
66 */
67 public class Attribute {
68
69 /**
70 * The type of this attribute.
71 */
72 public final String type;
73
74 /**
75 * The raw value of this attribute, used only for unknown attributes.
76 */
77 byte[] value;
78
79 /**
80 * The next attribute in this attribute list. May be <tt>null</tt>.
81 */
82 Attribute next;
83
84 /**
85 * Constructs a new empty attribute.
86 *
87 * @param type
88 * the type of the attribute.
89 */
90 protected Attribute(final String type) {
91 this.type = type;
92 }
93
94 /**
95 * Returns <tt>true</tt> if this type of attribute is unknown. The default
96 * implementation of this method always returns <tt>true</tt>.
97 *
98 * @return <tt>true</tt> if this type of attribute is unknown.
99 */
100 public boolean isUnknown() {
101 return true;
102 }
103
104 /**
105 * Returns <tt>true</tt> if this type of attribute is a code attribute.
106 *
107 * @return <tt>true</tt> if this type of attribute is a code attribute.
108 */
109 public boolean isCodeAttribute() {
110 return false;
111 }
112
113 /**
114 * Returns the labels corresponding to this attribute.
115 *
116 * @return the labels corresponding to this attribute, or <tt>null</tt> if
117 * this attribute is not a code attribute that contains labels.
118 */
119 protected Label[] getLabels() {
120 return null;
121 }
122
123 /**
124 * Reads a {@link #type type} attribute. This method must return a
125 * <i>new</i> {@link Attribute} object, of type {@link #type type},
126 * corresponding to the <tt>len</tt> bytes starting at the given offset, in
127 * the given class reader.
128 *
129 * @param cr
130 * the class that contains the attribute to be read.
131 * @param off
132 * index of the first byte of the attribute's content in
133 * {@link ClassReader#b cr.b}. The 6 attribute header bytes,
134 * containing the type and the length of the attribute, are not
135 * taken into account here.
136 * @param len
137 * the length of the attribute's content.
138 * @param buf
139 * buffer to be used to call {@link ClassReader#readUTF8
140 * readUTF8}, {@link ClassReader#readClass(int,char[]) readClass}
141 * or {@link ClassReader#readConst readConst}.
142 * @param codeOff
143 * index of the first byte of code's attribute content in
144 * {@link ClassReader#b cr.b}, or -1 if the attribute to be read
145 * is not a code attribute. The 6 attribute header bytes,
146 * containing the type and the length of the attribute, are not
147 * taken into account here.
148 * @param labels
149 * the labels of the method's code, or <tt>null</tt> if the
150 * attribute to be read is not a code attribute.
151 * @return a <i>new</i> {@link Attribute} object corresponding to the given
152 * bytes.
153 */
154 protected Attribute read(final ClassReader cr, final int off,
155 final int len, final char[] buf, final int codeOff,
156 final Label[] labels) {
157 Attribute attr = new Attribute(type);
158 attr.value = new byte[len];
159 System.arraycopy(cr.b, off, attr.value, 0, len);
160 return attr;
161 }
162
163 /**
164 * Returns the byte array form of this attribute.
165 *
166 * @param cw
167 * the class to which this attribute must be added. This
168 * parameter can be used to add to the constant pool of this
169 * class the items that corresponds to this attribute.
170 * @param code
171 * the bytecode of the method corresponding to this code
172 * attribute, or <tt>null</tt> if this attribute is not a code
173 * attributes.
174 * @param len
175 * the length of the bytecode of the method corresponding to this
176 * code attribute, or <tt>null</tt> if this attribute is not a
177 * code attribute.
178 * @param maxStack
179 * the maximum stack size of the method corresponding to this
180 * code attribute, or -1 if this attribute is not a code
181 * attribute.
182 * @param maxLocals
183 * the maximum number of local variables of the method
184 * corresponding to this code attribute, or -1 if this attribute
185 * is not a code attribute.
186 * @return the byte array form of this attribute.
187 */
188 protected ByteVector write(final ClassWriter cw, final byte[] code,
189 final int len, final int maxStack, final int maxLocals) {
190 ByteVector v = new ByteVector();
191 v.data = value;
192 v.length = value.length;
193 return v;
194 }
195
196 /**
197 * Returns the length of the attribute list that begins with this attribute.
198 *
199 * @return the length of the attribute list that begins with this attribute.
200 */
201 final int getCount() {
202 int count = 0;
203 Attribute attr = this;
204 while (attr != null) {
205 count += 1;
206 attr = attr.next;
207 }
208 return count;
209 }
210
211 /**
212 * Returns the size of all the attributes in this attribute list.
213 *
214 * @param cw
215 * the class writer to be used to convert the attributes into
216 * byte arrays, with the {@link #write write} method.
217 * @param code
218 * the bytecode of the method corresponding to these code
219 * attributes, or <tt>null</tt> if these attributes are not code
220 * attributes.
221 * @param len
222 * the length of the bytecode of the method corresponding to
223 * these code attributes, or <tt>null</tt> if these attributes
224 * are not code attributes.
225 * @param maxStack
226 * the maximum stack size of the method corresponding to these
227 * code attributes, or -1 if these attributes are not code
228 * attributes.
229 * @param maxLocals
230 * the maximum number of local variables of the method
231 * corresponding to these code attributes, or -1 if these
232 * attributes are not code attributes.
233 * @return the size of all the attributes in this attribute list. This size
234 * includes the size of the attribute headers.
235 */
236 final int getSize(final ClassWriter cw, final byte[] code, final int len,
237 final int maxStack, final int maxLocals) {
238 Attribute attr = this;
239 int size = 0;
240 while (attr != null) {
241 cw.newUTF8(attr.type);
242 size += attr.write(cw, code, len, maxStack, maxLocals).length + 6;
243 attr = attr.next;
244 }
245 return size;
246 }
247
248 /**
249 * Writes all the attributes of this attribute list in the given byte
250 * vector.
251 *
252 * @param cw
253 * the class writer to be used to convert the attributes into
254 * byte arrays, with the {@link #write write} method.
255 * @param code
256 * the bytecode of the method corresponding to these code
257 * attributes, or <tt>null</tt> if these attributes are not code
258 * attributes.
259 * @param len
260 * the length of the bytecode of the method corresponding to
261 * these code attributes, or <tt>null</tt> if these attributes
262 * are not code attributes.
263 * @param maxStack
264 * the maximum stack size of the method corresponding to these
265 * code attributes, or -1 if these attributes are not code
266 * attributes.
267 * @param maxLocals
268 * the maximum number of local variables of the method
269 * corresponding to these code attributes, or -1 if these
270 * attributes are not code attributes.
271 * @param out
272 * where the attributes must be written.
273 */
274 final void put(final ClassWriter cw, final byte[] code, final int len,
275 final int maxStack, final int maxLocals, final ByteVector out) {
276 Attribute attr = this;
277 while (attr != null) {
278 ByteVector b = attr.write(cw, code, len, maxStack, maxLocals);
279 out.putShort(cw.newUTF8(attr.type)).putInt(b.length);
280 out.putByteArray(b.data, 0, b.length);
281 attr = attr.next;
282 }
283 }
284 }