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 package org.apache.commons.compress.harmony.unpack200.bytecode;
18
19 import java.io.DataOutputStream;
20 import java.io.IOException;
21
22 import org.apache.commons.compress.harmony.unpack200.Segment;
23 import org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm;
24
25 /**
26 * A bytecode class file entry.
27 */
28 public class ByteCode extends ClassFileEntry {
29
30 private static ByteCode[] noArgByteCodes = new ByteCode[255];
31
32 public static ByteCode getByteCode(final int opcode) {
33 final int byteOpcode = 0xFF & opcode;
34 if (ByteCodeForm.get(byteOpcode).hasNoOperand()) {
35 if (null == noArgByteCodes[byteOpcode]) {
36 noArgByteCodes[byteOpcode] = new ByteCode(byteOpcode);
37 }
38 return noArgByteCodes[byteOpcode];
39 }
40 return new ByteCode(byteOpcode);
41 }
42
43 private final ByteCodeForm byteCodeForm;
44
45 private ClassFileEntry[] nested;
46 private int[][] nestedPositions;
47 private int[] rewrite;
48
49 private int byteCodeOffset = -1;
50 private int[] byteCodeTargets;
51
52 protected ByteCode(final int opcode) {
53 this(opcode, NONE);
54 }
55
56 protected ByteCode(final int opcode, final ClassFileEntry[] nested) {
57 this.byteCodeForm = ByteCodeForm.get(opcode);
58 this.rewrite = byteCodeForm.getRewriteCopy();
59 this.nested = nested;
60 }
61
62 /**
63 * Some ByteCodes (in particular, those with labels need to be fixed up after all the bytecodes in the CodeAttribute have been added. (This can't be done
64 * beforehand because the CodeAttribute needs to be complete before targets can be assigned.)
65 *
66 * @param codeAttribute the code attribute
67 */
68 public void applyByteCodeTargetFixup(final CodeAttribute codeAttribute) {
69 getByteCodeForm().fixUpByteCodeTargets(this, codeAttribute);
70 }
71
72 @Override
73 protected void doWrite(final DataOutputStream dos) throws IOException {
74 for (final int element : rewrite) {
75 dos.writeByte(element);
76 }
77 }
78
79 @Override
80 public boolean equals(final Object obj) {
81 return this == obj;
82 }
83
84 public void extractOperands(final OperandManager operandManager, final Segment segment, final int codeLength) {
85 // Given an OperandTable, figure out which operands
86 // the receiver needs and stuff them in operands.
87 // Later on the operands can be rewritten (But that's
88 // later, not now).
89 final ByteCodeForm currentByteCodeForm = getByteCodeForm();
90 currentByteCodeForm.setByteCodeOperands(this, operandManager, codeLength);
91 }
92
93 protected ByteCodeForm getByteCodeForm() {
94 return byteCodeForm;
95 }
96
97 public int getByteCodeIndex() {
98 return byteCodeOffset;
99 }
100
101 public int[] getByteCodeTargets() {
102 return byteCodeTargets;
103 }
104
105 public int getLength() {
106 return rewrite.length;
107 }
108
109 public String getName() {
110 return getByteCodeForm().getName();
111 }
112
113 @Override
114 public ClassFileEntry[] getNestedClassFileEntries() {
115 return nested;
116 }
117
118 public int[] getNestedPosition(final int index) {
119 return getNestedPositions()[index];
120 }
121
122 public int[][] getNestedPositions() {
123 return nestedPositions;
124 }
125
126 public int getOpcode() {
127 return getByteCodeForm().getOpcode();
128 }
129
130 /**
131 * Some bytecodes (the ones with variable lengths) can't have a static rewrite array - they need the ability to update the array. This method permits their
132 * associated bytecode formst to query their rewrite array.
133 *
134 * Note that this should not be called from bytecodes which have a static rewrite; use the table in ByteCodeForm instead to specify those rewrites.
135 *
136 * @return Some bytecodes.
137 */
138 public int[] getRewrite() {
139 return rewrite;
140 }
141
142 @Override
143 public int hashCode() {
144 return objectHashCode();
145 }
146
147 /**
148 * This method will answer true if the receiver is a multi-bytecode instruction (such as aload0_putfield_super); otherwise, it will answer false.
149 *
150 * @return boolean true if multibytecode, false otherwise
151 */
152 public boolean hasMultipleByteCodes() {
153 return getByteCodeForm().hasMultipleByteCodes();
154 }
155
156 public boolean nestedMustStartClassPool() {
157 return byteCodeForm.nestedMustStartClassPool();
158 }
159
160 /*
161 * (non-Javadoc)
162 *
163 * @see org.apache.commons.compress.harmony.unpack200.bytecode.ClassFileEntry#resolve(org.apache.commons.compress.harmony
164 * .unpack200.bytecode.ClassConstantPool)
165 */
166 @Override
167 protected void resolve(final ClassConstantPool pool) {
168 super.resolve(pool);
169 if (nested.length > 0) {
170 // Update the bytecode rewrite array so that it points
171 // to the elements of the nested array.
172 for (int index = 0; index < nested.length; index++) {
173 final int argLength = getNestedPosition(index)[1];
174 switch (argLength) {
175
176 case 1:
177 setOperandByte(pool.indexOf(nested[index]), getNestedPosition(index)[0]);
178 break;
179
180 case 2:
181 setOperand2Bytes(pool.indexOf(nested[index]), getNestedPosition(index)[0]);
182 break;
183
184 default:
185 throw new Error("Unhandled resolve " + this);
186 }
187 }
188 }
189 }
190
191 /**
192 * ByteCodes may need to know their position in the code array (in particular, label byte codes need to know where they are in order to calculate their
193 * targets). This method lets the CodeAttribute specify where the byte code is.
194 *
195 * Since there are no aload0+label instructions, this method doesn't worry about multioperation bytecodes.
196 *
197 * @param byteCodeOffset int position in code array.
198 */
199 public void setByteCodeIndex(final int byteCodeOffset) {
200 this.byteCodeOffset = byteCodeOffset;
201 }
202
203 /**
204 * Some ByteCodes (in particular, those with labels) have to keep track of byteCodeTargets. These are initially offsets in the CodeAttribute array relative
205 * to the byteCodeOffset, but later get fixed up to point to the absolute position in the CodeAttribute array. This method sets the targets.
206 *
207 * @param byteCodeTargets int index in array
208 */
209 public void setByteCodeTargets(final int[] byteCodeTargets) {
210 this.byteCodeTargets = byteCodeTargets;
211 }
212
213 public void setNested(final ClassFileEntry[] nested) {
214 this.nested = nested;
215 }
216
217 /**
218 * nestedPositions is an array of arrays of ints. Each subarray specifies a position of a nested element (from the nested[] array) and the length of that
219 * element.
220 *
221 * For instance, one might have a nested of: {CPClass java/lang/Foo, CPFloat 3.14} The nestedPositions would then be: {{0,2},{2,2}} In other words, when the
222 * bytecode is resolved, the CPClass will be resolved to an int and inserted at position 0 and 1 of the rewrite arguments (the first occurrences of -1). The
223 * CPFloat will be resolved to an int position and inserted at positions 2 and 3 of the rewrite arguments.
224 *
225 * @param nestedPositions Each subarray specifies a position of a nested element (from the nested[] array) and the length of that element.
226 */
227 public void setNestedPositions(final int[][] nestedPositions) {
228 this.nestedPositions = nestedPositions;
229 }
230
231 /**
232 * Given an int operand, set the rewrite bytes for that position and the one immediately following it to a high-byte, low-byte encoding of the operand.
233 *
234 * @param operand int to set the rewrite bytes to
235 * @param position int position in the operands of the rewrite bytes. For a rewrite array of {100, -1, -1, -1} position 0 is the first -1, position 1 is the
236 * second -1, etc.
237 */
238 public void setOperand2Bytes(final int operand, final int position) {
239 final int firstOperandIndex = getByteCodeForm().firstOperandIndex();
240 final int byteCodeFormLength = getByteCodeForm().getRewrite().length;
241 if (firstOperandIndex < 1) {
242 // No operand rewriting permitted for this bytecode
243 throw new Error("Trying to rewrite " + this + " that has no rewrite");
244 }
245
246 if (firstOperandIndex + position + 1 > byteCodeFormLength) {
247 throw new Error("Trying to rewrite " + this + " with an int at position " + position + " but this won't fit in the rewrite array");
248 }
249
250 rewrite[firstOperandIndex + position] = (operand & 0xFF00) >> 8;
251 rewrite[firstOperandIndex + position + 1] = operand & 0xFF;
252 }
253
254 /**
255 * Given an int operand, treat it as a byte and set the rewrite byte for that position to that value. Mask of anything beyond 0xFF.
256 *
257 * @param operand int to set the rewrite byte to (unsigned)
258 * @param position int position in the operands of the rewrite bytes. For a rewrite array of {100, -1, -1, -1} position 0 is the first -1, position 1 is the
259 * second -1, etc.
260 */
261 public void setOperandByte(final int operand, final int position) {
262 final int firstOperandIndex = getByteCodeForm().firstOperandIndex();
263 final int byteCodeFormLength = getByteCodeForm().operandLength();
264 if (firstOperandIndex < 1) {
265 // No operand rewriting permitted for this bytecode
266 throw new Error("Trying to rewrite " + this + " that has no rewrite");
267 }
268
269 if (firstOperandIndex + position > byteCodeFormLength) {
270 throw new Error("Trying to rewrite " + this + " with an byte at position " + position + " but this won't fit in the rewrite array");
271 }
272
273 rewrite[firstOperandIndex + position] = operand & 0xFF;
274 }
275
276 /**
277 * Given an array of ints which correspond to bytes in the operand of the bytecode, set the rewrite bytes of the operand to be the appropriate values. All
278 * values in operands[] will be masked with 0xFF so they fit into a byte.
279 *
280 * @param operands int[] rewrite operand bytes
281 */
282 public void setOperandBytes(final int[] operands) {
283 final int firstOperandIndex = getByteCodeForm().firstOperandIndex();
284 final int byteCodeFormLength = getByteCodeForm().operandLength();
285 if (firstOperandIndex < 1) {
286 // No operand rewriting permitted for this bytecode
287 throw new Error("Trying to rewrite " + this + " that has no rewrite");
288 }
289
290 if (byteCodeFormLength != operands.length) {
291 throw new Error("Trying to rewrite " + this + " with " + operands.length + " but bytecode has length " + byteCodeForm.operandLength());
292 }
293
294 for (int index = 0; index < byteCodeFormLength; index++) {
295 rewrite[index + firstOperandIndex] = operands[index] & 0xFF;
296 }
297 }
298
299 /**
300 * This is just like setOperandInt, but takes special care when the operand is less than 0 to make sure it's written correctly.
301 *
302 * @param operand int to set the rewrite bytes to
303 * @param position int position of the operands in the rewrite bytes
304 */
305 public void setOperandSigned2Bytes(final int operand, final int position) {
306 if (operand >= 0) {
307 setOperand2Bytes(operand, position);
308 } else {
309 final int twosComplementOperand = 0x10000 + operand;
310 setOperand2Bytes(twosComplementOperand, position);
311 }
312 }
313
314 /**
315 * Some bytecodes (the ones with variable lengths) can't have a static rewrite array - they need the ability to update the array. This method permits that.
316 *
317 * Note that this should not be called from bytecodes which have a static rewrite; use the table in ByteCodeForm instead to specify those rewrites.
318 *
319 * @param rewrite Some bytecodes.
320 */
321 public void setRewrite(final int[] rewrite) {
322 this.rewrite = rewrite;
323 }
324
325 @Override
326 public String toString() {
327 return getByteCodeForm().getName();
328 }
329 }