1 /*
2 * Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 */
26 package jdk.internal.classfile.impl;
27
28 import java.lang.classfile.BufWriter;
29 import java.lang.classfile.constantpool.ClassEntry;
30 import java.lang.classfile.constantpool.ConstantPool;
31 import java.lang.classfile.constantpool.ConstantPoolBuilder;
32 import java.lang.classfile.constantpool.PoolEntry;
33 import java.util.Arrays;
34
35 import jdk.internal.access.JavaLangAccess;
36 import jdk.internal.access.SharedSecrets;
37 import jdk.internal.vm.annotation.ForceInline;
38
39 import static java.lang.classfile.constantpool.PoolEntry.TAG_UTF8;
40 import static jdk.internal.util.ModifiedUtf.putChar;
41 import static jdk.internal.util.ModifiedUtf.utfLen;
42
43 public final class BufWriterImpl implements BufWriter {
44 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
45
46 private final ConstantPoolBuilder constantPool;
47 private final ClassFileImpl context;
48 private LabelContext labelContext;
49 private boolean labelsMatch;
50 private final ClassEntry thisClass;
51 private final int majorVersion;
52 byte[] elems;
53 int offset = 0;
54
55 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context) {
56 this(constantPool, context, 64, null, 0);
57 }
58
59 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context, int initialSize) {
60 this(constantPool, context, initialSize, null, 0);
61 }
62
63 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context, int initialSize, ClassEntry thisClass, int majorVersion) {
64 this.constantPool = constantPool;
65 this.context = context;
66 elems = new byte[initialSize];
67 this.thisClass = thisClass;
68 this.majorVersion = majorVersion;
69 }
70
71 @Override
72 public ConstantPoolBuilder constantPool() {
73 return constantPool;
74 }
75
76 public LabelContext labelContext() {
77 return labelContext;
78 }
79
80 public void setLabelContext(LabelContext labelContext, boolean labelsMatch) {
81 this.labelContext = labelContext;
82 this.labelsMatch = labelsMatch;
83 }
84
85 public boolean labelsMatch(LabelContext lc) {
86 return labelsMatch
87 && labelContext instanceof DirectCodeBuilder dcb
88 && dcb.original == lc;
89 }
90
91 @Override
92 public boolean canWriteDirect(ConstantPool other) {
93 return constantPool.canWriteDirect(other);
94 }
95
96 public ClassEntry thisClass() {
97 return thisClass;
98 }
99
100 public int getMajorVersion() {
101 return majorVersion;
102 }
103
104 public ClassFileImpl context() {
105 return context;
106 }
107
108 @Override
109 public void writeU1(int x) {
110 reserveSpace(1);
111 elems[offset++] = (byte) x;
112 }
113
114 @ForceInline
115 @Override
116 public void writeU2(int x) {
117 reserveSpace(2);
118 byte[] elems = this.elems;
119 int offset = this.offset;
120 elems[offset ] = (byte) (x >> 8);
121 elems[offset + 1] = (byte) x;
122 this.offset = offset + 2;
123 }
124
125 @ForceInline
126 public void writeU1U1(int x1, int x2) {
127 reserveSpace(2);
128 byte[] elems = this.elems;
129 int offset = this.offset;
130 elems[offset ] = (byte) x1;
131 elems[offset + 1] = (byte) x2;
132 this.offset = offset + 2;
133 }
134
135 public void writeU1U2(int u1, int u2) {
136 reserveSpace(3);
137 byte[] elems = this.elems;
138 int offset = this.offset;
139 elems[offset ] = (byte) u1;
140 elems[offset + 1] = (byte) (u2 >> 8);
141 elems[offset + 2] = (byte) u2;
142 this.offset = offset + 3;
143 }
144
145 public void writeU1U1U1(int x1, int x2, int x3) {
146 reserveSpace(3);
147 byte[] elems = this.elems;
148 int offset = this.offset;
149 elems[offset ] = (byte) x1;
150 elems[offset + 1] = (byte) x2;
151 elems[offset + 2] = (byte) x3;
152 this.offset = offset + 3;
153 }
154
155 public void writeU1U1U2(int x1, int x2, int x3) {
156 reserveSpace(4);
157 byte[] elems = this.elems;
158 int offset = this.offset;
159 elems[offset ] = (byte) x1;
160 elems[offset + 1] = (byte) x2;
161 elems[offset + 2] = (byte) (x3 >> 8);
162 elems[offset + 3] = (byte) x3;
163 this.offset = offset + 4;
164 }
165
166 public void writeU1U2U2(int x1, int x2, int x3) {
167 reserveSpace(5);
168 byte[] elems = this.elems;
169 int offset = this.offset;
170 elems[offset ] = (byte) x1;
171 elems[offset + 1] = (byte) (x2 >> 8);
172 elems[offset + 2] = (byte) x2;
173 elems[offset + 3] = (byte) (x3 >> 8);
174 elems[offset + 4] = (byte) x3;
175 this.offset = offset + 5;
176 }
177
178 public void writeU2U1(int x1, int x2) {
179 reserveSpace(3);
180 byte[] elems = this.elems;
181 int offset = this.offset;
182 elems[offset ] = (byte) (x1 >> 8);
183 elems[offset + 1] = (byte) x1;
184 elems[offset + 2] = (byte) x2;
185 this.offset = offset + 3;
186 }
187
188 public void writeU2U2(int x1, int x2) {
189 reserveSpace(4);
190 byte[] elems = this.elems;
191 int offset = this.offset;
192 elems[offset ] = (byte) (x1 >> 8);
193 elems[offset + 1] = (byte) x1;
194 elems[offset + 2] = (byte) (x2 >> 8);
195 elems[offset + 3] = (byte) x2;
196 this.offset = offset + 4;
197 }
198
199 public void writeU2U2U2(int x1, int x2, int x3) {
200 reserveSpace(6);
201 byte[] elems = this.elems;
202 int offset = this.offset;
203 elems[offset ] = (byte) (x1 >> 8);
204 elems[offset + 1] = (byte) x1;
205 elems[offset + 2] = (byte) (x2 >> 8);
206 elems[offset + 3] = (byte) x2;
207 elems[offset + 4] = (byte) (x3 >> 8);
208 elems[offset + 5] = (byte) x3;
209 this.offset = offset + 6;
210 }
211
212 @Override
213 public void writeInt(int x) {
214 reserveSpace(4);
215 byte[] elems = this.elems;
216 int offset = this.offset;
217 elems[offset ] = (byte) (x >> 24);
218 elems[offset + 1] = (byte) (x >> 16);
219 elems[offset + 2] = (byte) (x >> 8);
220 elems[offset + 3] = (byte) x;
221 this.offset = offset + 4;
222 }
223
224 public void writeIntInt(int x1, int x2) {
225 reserveSpace(8);
226 byte[] elems = this.elems;
227 int offset = this.offset;
228 elems[offset ] = (byte) (x1 >> 24);
229 elems[offset + 1] = (byte) (x1 >> 16);
230 elems[offset + 2] = (byte) (x1 >> 8);
231 elems[offset + 3] = (byte) x1;
232 elems[offset + 4] = (byte) (x2 >> 24);
233 elems[offset + 5] = (byte) (x2 >> 16);
234 elems[offset + 6] = (byte) (x2 >> 8);
235 elems[offset + 7] = (byte) x2;
236 this.offset = offset + 8;
237 }
238
239 @Override
240 public void writeFloat(float x) {
241 writeInt(Float.floatToIntBits(x));
242 }
243
244 @Override
245 public void writeLong(long x) {
246 reserveSpace(8);
247 byte[] elems = this.elems;
248 int offset = this.offset;
249 elems[offset ] = (byte) (x >> 56);
250 elems[offset + 1] = (byte) (x >> 48);
251 elems[offset + 2] = (byte) (x >> 40);
252 elems[offset + 3] = (byte) (x >> 32);
253 elems[offset + 4] = (byte) (x >> 24);
254 elems[offset + 5] = (byte) (x >> 16);
255 elems[offset + 6] = (byte) (x >> 8);
256 elems[offset + 7] = (byte) x;
257 this.offset = offset + 8;
258 }
259
260 @Override
261 public void writeDouble(double x) {
262 writeLong(Double.doubleToLongBits(x));
263 }
264
265 @Override
266 public void writeBytes(byte[] arr) {
267 writeBytes(arr, 0, arr.length);
268 }
269
270 public void writeBytes(BufWriterImpl other) {
271 writeBytes(other.elems, 0, other.offset);
272 }
273
274 @SuppressWarnings("deprecation")
275 void writeUtfEntry(String str) {
276 int strlen = str.length();
277 int countNonZeroAscii = JLA.countNonZeroAscii(str);
278 int utflen = utfLen(str, countNonZeroAscii);
279 Util.checkU2(utflen, "utf8 length");
280 reserveSpace(utflen + 3);
281
282 int offset = this.offset;
283 byte[] elems = this.elems;
284
285 elems[offset ] = (byte) TAG_UTF8;
286 elems[offset + 1] = (byte) (utflen >> 8);
287 elems[offset + 2] = (byte) utflen;
288 offset += 3;
289
290 str.getBytes(0, countNonZeroAscii, elems, offset);
291 offset += countNonZeroAscii;
292
293 for (int i = countNonZeroAscii; i < strlen; i++) {
294 offset = putChar(elems, offset, str.charAt(i));
295 }
296
297 this.offset = offset;
298 }
299
300 @Override
301 public void writeBytes(byte[] arr, int start, int length) {
302 reserveSpace(length);
303 System.arraycopy(arr, start, elems, offset, length);
304 offset += length;
305 }
306
307 @Override
308 public void patchInt(int offset, int size, int value) {
309 int prevOffset = this.offset;
310 this.offset = offset;
311 writeIntBytes(size, value);
312 this.offset = prevOffset;
313 }
314
315 public void patchU2(int offset, int x) {
316 byte[] elems = this.elems;
317 elems[offset ] = (byte) (x >> 8);
318 elems[offset + 1] = (byte) x;
319 }
320
321 public void patchInt(int offset, int x) {
322 byte[] elems = this.elems;
323 elems[offset ] = (byte) (x >> 24);
324 elems[offset + 1] = (byte) (x >> 16);
325 elems[offset + 2] = (byte) (x >> 8);
326 elems[offset + 3] = (byte) x;
327 }
328
329 @Override
330 public void writeIntBytes(int intSize, long intValue) {
331 reserveSpace(intSize);
332 for (int i = 0; i < intSize; i++) {
333 elems[offset++] = (byte) ((intValue >> 8 * (intSize - i - 1)) & 0xFF);
334 }
335 }
336
337 /**
338 * Skip a few bytes in the output buffer. The skipped area has undefined value.
339 * @param bytes number of bytes to skip
340 * @return the index, for later patching
341 */
342 public int skip(int bytes) {
343 int now = offset;
344 reserveSpace(bytes);
345 offset += bytes;
346 return now;
347 }
348
349 @Override
350 public void reserveSpace(int freeBytes) {
351 int minCapacity = offset + freeBytes;
352 if (minCapacity > elems.length) {
353 grow(minCapacity);
354 }
355 }
356
357 private void grow(int minCapacity) {
358 int newsize = elems.length * 2;
359 while (minCapacity > newsize) {
360 newsize *= 2;
361 }
362 elems = Arrays.copyOf(elems, newsize);
363 }
364
365 @Override
366 public int size() {
367 return offset;
368 }
369
370 public RawBytecodeHelper.CodeRange bytecodeView() {
371 return RawBytecodeHelper.of(elems, offset);
372 }
373
374 public void copyTo(byte[] array, int bufferOffset) {
375 System.arraycopy(elems, 0, array, bufferOffset, size());
376 }
377
378 // writeIndex methods ensure that any CP info written
379 // is relative to the correct constant pool
380
381 public int cpIndex(PoolEntry entry) {
382 int idx = AbstractPoolEntry.maybeClone(constantPool, entry).index();
383 if (idx < 1 || idx > Character.MAX_VALUE)
384 throw invalidIndex(idx, entry);
385 return idx;
386 }
387
388 public int cpIndexOrZero(PoolEntry entry) {
389 if (entry == null || entry.index() == 0)
390 return 0;
391 return cpIndex(entry);
392 }
393
394 @ForceInline
395 @Override
396 public void writeIndex(PoolEntry entry) {
397 writeU2(cpIndex(entry));
398 }
399
400 // Null checks entry
401 public void writeIndex(int bytecode, PoolEntry entry) {
402 writeU1U2(bytecode, cpIndex(entry));
403 }
404
405 static IllegalArgumentException invalidIndex(int idx, PoolEntry entry) {
406 return new IllegalArgumentException(idx + " is not a valid index. Entry: " + entry);
407 }
408
409 @Override
410 public void writeIndexOrZero(PoolEntry entry) {
411 writeU2(cpIndexOrZero(entry));
412 }
413
414 /**
415 * Join head and tail into an exact-size buffer
416 */
417 static byte[] join(BufWriterImpl head, BufWriterImpl tail) {
418 byte[] result = new byte[head.size() + tail.size()];
419 head.copyTo(result, 0);
420 tail.copyTo(result, head.size());
421 return result;
422 }
423 }