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.ClassModel;
30 import java.lang.classfile.constantpool.ClassEntry;
31 import java.lang.classfile.constantpool.ConstantPool;
32 import java.lang.classfile.constantpool.ConstantPoolBuilder;
33 import java.lang.classfile.constantpool.PoolEntry;
34 import java.util.Arrays;
35 import java.util.HashSet;
36
37 import jdk.internal.access.JavaLangAccess;
38 import jdk.internal.access.SharedSecrets;
39 import jdk.internal.vm.annotation.ForceInline;
40
41 import static java.lang.classfile.ClassFile.*;
42 import static java.lang.classfile.constantpool.PoolEntry.TAG_UTF8;
43 import static jdk.internal.util.ModifiedUtf.putChar;
44 import static jdk.internal.util.ModifiedUtf.utfLen;
45
46 public final class BufWriterImpl implements BufWriter {
47 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
48
49 private final ConstantPoolBuilder constantPool;
50 private final ClassFileImpl context;
51 private LabelContext labelContext;
52 private WritableField.UnsetField[] strictInstanceFields; // do not modify array contents
53 private ClassModel lastStrictCheckClass; // buf writer has short life, so do not need weak here
54 private boolean lastStrictCheckResult;
55 private boolean labelsMatch;
56 private final ClassEntry thisClass;
57 private final int majorVersion;
58 byte[] elems;
59 int offset = 0;
60
61 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context) {
62 this(constantPool, context, 64, null, 0);
63 }
64
65 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context, int initialSize) {
66 this(constantPool, context, initialSize, null, 0);
67 }
68
69 public BufWriterImpl(ConstantPoolBuilder constantPool, ClassFileImpl context, int initialSize, ClassEntry thisClass, int majorVersion) {
70 this.constantPool = constantPool;
71 this.context = context;
72 elems = new byte[initialSize];
73 this.thisClass = thisClass;
74 this.majorVersion = majorVersion;
75 }
76
77 public boolean strictFieldsMatch(ClassModel cm) {
78 // We have a cache because this check will be called multiple times
79 // if a MethodModel is sent wholesale
80 if (lastStrictCheckClass == cm) {
81 return lastStrictCheckResult;
82 }
83
84 var result = doStrictFieldsMatchCheck(cm);
85 lastStrictCheckClass = cm;
86 lastStrictCheckResult = result;
87 return result;
88 }
89
90 private boolean doStrictFieldsMatchCheck(ClassModel cm) {
91 // TODO only check for preview class files?
92 // UTF8 Entry can be used as equality objects
93 var checks = new HashSet<>(Arrays.asList(getStrictInstanceFields()));
94 for (var f : cm.fields()) {
95 if ((f.flags().flagsMask() & (ACC_STATIC | ACC_STRICT_INIT)) == ACC_STRICT_INIT) {
96 if (!checks.remove(new WritableField.UnsetField(f.fieldName(), f.fieldType()))) {
97 return false; // Field mismatch!
98 }
99 }
100 }
101 return checks.isEmpty();
102 }
103
104 @Override
105 public ConstantPoolBuilder constantPool() {
106 return constantPool;
107 }
108
109 public LabelContext labelContext() {
110 return labelContext;
111 }
112
113 public void setLabelContext(LabelContext labelContext, boolean labelsMatch) {
114 this.labelContext = labelContext;
115 this.labelsMatch = labelsMatch;
116 }
117
118 public WritableField.UnsetField[] getStrictInstanceFields() {
119 assert strictInstanceFields != null : "should access only after setter call in DirectClassBuilder";
120 return strictInstanceFields;
121 }
122
123 public void setStrictInstanceFields(WritableField.UnsetField[] strictInstanceFields) {
124 this.strictInstanceFields = strictInstanceFields;
125 }
126
127
128 public boolean labelsMatch(LabelContext lc) {
129 return labelsMatch
130 && labelContext instanceof DirectCodeBuilder dcb
131 && dcb.original == lc;
132 }
133
134 @Override
135 public boolean canWriteDirect(ConstantPool other) {
136 return constantPool.canWriteDirect(other);
137 }
138
139 public ClassEntry thisClass() {
140 return thisClass;
141 }
142
143 public int getMajorVersion() {
144 return majorVersion;
145 }
146
147 public ClassFileImpl context() {
148 return context;
149 }
150
151 @Override
152 public void writeU1(int x) {
153 reserveSpace(1);
154 elems[offset++] = (byte) x;
155 }
156
157 @ForceInline
158 @Override
159 public void writeU2(int x) {
160 reserveSpace(2);
161 byte[] elems = this.elems;
162 int offset = this.offset;
163 elems[offset ] = (byte) (x >> 8);
164 elems[offset + 1] = (byte) x;
165 this.offset = offset + 2;
166 }
167
168 @ForceInline
169 public void writeU1U1(int x1, int x2) {
170 reserveSpace(2);
171 byte[] elems = this.elems;
172 int offset = this.offset;
173 elems[offset ] = (byte) x1;
174 elems[offset + 1] = (byte) x2;
175 this.offset = offset + 2;
176 }
177
178 public void writeU1U2(int u1, int u2) {
179 reserveSpace(3);
180 byte[] elems = this.elems;
181 int offset = this.offset;
182 elems[offset ] = (byte) u1;
183 elems[offset + 1] = (byte) (u2 >> 8);
184 elems[offset + 2] = (byte) u2;
185 this.offset = offset + 3;
186 }
187
188 public void writeU1U1U1(int x1, int x2, int x3) {
189 reserveSpace(3);
190 byte[] elems = this.elems;
191 int offset = this.offset;
192 elems[offset ] = (byte) x1;
193 elems[offset + 1] = (byte) x2;
194 elems[offset + 2] = (byte) x3;
195 this.offset = offset + 3;
196 }
197
198 public void writeU1U1U2(int x1, int x2, int x3) {
199 reserveSpace(4);
200 byte[] elems = this.elems;
201 int offset = this.offset;
202 elems[offset ] = (byte) x1;
203 elems[offset + 1] = (byte) x2;
204 elems[offset + 2] = (byte) (x3 >> 8);
205 elems[offset + 3] = (byte) x3;
206 this.offset = offset + 4;
207 }
208
209 public void writeU1U2U2(int x1, int x2, int x3) {
210 reserveSpace(5);
211 byte[] elems = this.elems;
212 int offset = this.offset;
213 elems[offset ] = (byte) x1;
214 elems[offset + 1] = (byte) (x2 >> 8);
215 elems[offset + 2] = (byte) x2;
216 elems[offset + 3] = (byte) (x3 >> 8);
217 elems[offset + 4] = (byte) x3;
218 this.offset = offset + 5;
219 }
220
221 public void writeU2U1(int x1, int x2) {
222 reserveSpace(3);
223 byte[] elems = this.elems;
224 int offset = this.offset;
225 elems[offset ] = (byte) (x1 >> 8);
226 elems[offset + 1] = (byte) x1;
227 elems[offset + 2] = (byte) x2;
228 this.offset = offset + 3;
229 }
230
231 public void writeU2U2(int x1, int x2) {
232 reserveSpace(4);
233 byte[] elems = this.elems;
234 int offset = this.offset;
235 elems[offset ] = (byte) (x1 >> 8);
236 elems[offset + 1] = (byte) x1;
237 elems[offset + 2] = (byte) (x2 >> 8);
238 elems[offset + 3] = (byte) x2;
239 this.offset = offset + 4;
240 }
241
242 public void writeU2U2U2(int x1, int x2, int x3) {
243 reserveSpace(6);
244 byte[] elems = this.elems;
245 int offset = this.offset;
246 elems[offset ] = (byte) (x1 >> 8);
247 elems[offset + 1] = (byte) x1;
248 elems[offset + 2] = (byte) (x2 >> 8);
249 elems[offset + 3] = (byte) x2;
250 elems[offset + 4] = (byte) (x3 >> 8);
251 elems[offset + 5] = (byte) x3;
252 this.offset = offset + 6;
253 }
254
255 @Override
256 public void writeInt(int x) {
257 reserveSpace(4);
258 byte[] elems = this.elems;
259 int offset = this.offset;
260 elems[offset ] = (byte) (x >> 24);
261 elems[offset + 1] = (byte) (x >> 16);
262 elems[offset + 2] = (byte) (x >> 8);
263 elems[offset + 3] = (byte) x;
264 this.offset = offset + 4;
265 }
266
267 public void writeIntInt(int x1, int x2) {
268 reserveSpace(8);
269 byte[] elems = this.elems;
270 int offset = this.offset;
271 elems[offset ] = (byte) (x1 >> 24);
272 elems[offset + 1] = (byte) (x1 >> 16);
273 elems[offset + 2] = (byte) (x1 >> 8);
274 elems[offset + 3] = (byte) x1;
275 elems[offset + 4] = (byte) (x2 >> 24);
276 elems[offset + 5] = (byte) (x2 >> 16);
277 elems[offset + 6] = (byte) (x2 >> 8);
278 elems[offset + 7] = (byte) x2;
279 this.offset = offset + 8;
280 }
281
282 @Override
283 public void writeFloat(float x) {
284 writeInt(Float.floatToIntBits(x));
285 }
286
287 @Override
288 public void writeLong(long x) {
289 reserveSpace(8);
290 byte[] elems = this.elems;
291 int offset = this.offset;
292 elems[offset ] = (byte) (x >> 56);
293 elems[offset + 1] = (byte) (x >> 48);
294 elems[offset + 2] = (byte) (x >> 40);
295 elems[offset + 3] = (byte) (x >> 32);
296 elems[offset + 4] = (byte) (x >> 24);
297 elems[offset + 5] = (byte) (x >> 16);
298 elems[offset + 6] = (byte) (x >> 8);
299 elems[offset + 7] = (byte) x;
300 this.offset = offset + 8;
301 }
302
303 @Override
304 public void writeDouble(double x) {
305 writeLong(Double.doubleToLongBits(x));
306 }
307
308 @Override
309 public void writeBytes(byte[] arr) {
310 writeBytes(arr, 0, arr.length);
311 }
312
313 public void writeBytes(BufWriterImpl other) {
314 writeBytes(other.elems, 0, other.offset);
315 }
316
317 @SuppressWarnings("deprecation")
318 void writeUtfEntry(String str) {
319 int strlen = str.length();
320 int countNonZeroAscii = JLA.countNonZeroAscii(str);
321 int utflen = utfLen(str, countNonZeroAscii);
322 Util.checkU2(utflen, "utf8 length");
323 reserveSpace(utflen + 3);
324
325 int offset = this.offset;
326 byte[] elems = this.elems;
327
328 elems[offset ] = (byte) TAG_UTF8;
329 elems[offset + 1] = (byte) (utflen >> 8);
330 elems[offset + 2] = (byte) utflen;
331 offset += 3;
332
333 str.getBytes(0, countNonZeroAscii, elems, offset);
334 offset += countNonZeroAscii;
335
336 for (int i = countNonZeroAscii; i < strlen; i++) {
337 offset = putChar(elems, offset, str.charAt(i));
338 }
339
340 this.offset = offset;
341 }
342
343 @Override
344 public void writeBytes(byte[] arr, int start, int length) {
345 reserveSpace(length);
346 System.arraycopy(arr, start, elems, offset, length);
347 offset += length;
348 }
349
350 @Override
351 public void patchInt(int offset, int size, int value) {
352 int prevOffset = this.offset;
353 this.offset = offset;
354 writeIntBytes(size, value);
355 this.offset = prevOffset;
356 }
357
358 public void patchU2(int offset, int x) {
359 byte[] elems = this.elems;
360 elems[offset ] = (byte) (x >> 8);
361 elems[offset + 1] = (byte) x;
362 }
363
364 public void patchInt(int offset, int x) {
365 byte[] elems = this.elems;
366 elems[offset ] = (byte) (x >> 24);
367 elems[offset + 1] = (byte) (x >> 16);
368 elems[offset + 2] = (byte) (x >> 8);
369 elems[offset + 3] = (byte) x;
370 }
371
372 @Override
373 public void writeIntBytes(int intSize, long intValue) {
374 reserveSpace(intSize);
375 for (int i = 0; i < intSize; i++) {
376 elems[offset++] = (byte) ((intValue >> 8 * (intSize - i - 1)) & 0xFF);
377 }
378 }
379
380 /**
381 * Skip a few bytes in the output buffer. The skipped area has undefined value.
382 * @param bytes number of bytes to skip
383 * @return the index, for later patching
384 */
385 public int skip(int bytes) {
386 int now = offset;
387 reserveSpace(bytes);
388 offset += bytes;
389 return now;
390 }
391
392 @Override
393 public void reserveSpace(int freeBytes) {
394 int minCapacity = offset + freeBytes;
395 if (minCapacity > elems.length) {
396 grow(minCapacity);
397 }
398 }
399
400 private void grow(int minCapacity) {
401 int newsize = elems.length * 2;
402 while (minCapacity > newsize) {
403 newsize *= 2;
404 }
405 elems = Arrays.copyOf(elems, newsize);
406 }
407
408 @Override
409 public int size() {
410 return offset;
411 }
412
413 public RawBytecodeHelper.CodeRange bytecodeView() {
414 return RawBytecodeHelper.of(elems, offset);
415 }
416
417 public void copyTo(byte[] array, int bufferOffset) {
418 System.arraycopy(elems, 0, array, bufferOffset, size());
419 }
420
421 // writeIndex methods ensure that any CP info written
422 // is relative to the correct constant pool
423
424 public int cpIndex(PoolEntry entry) {
425 int idx = AbstractPoolEntry.maybeClone(constantPool, entry).index();
426 if (idx < 1 || idx > Character.MAX_VALUE)
427 throw invalidIndex(idx, entry);
428 return idx;
429 }
430
431 public int cpIndexOrZero(PoolEntry entry) {
432 if (entry == null || entry.index() == 0)
433 return 0;
434 return cpIndex(entry);
435 }
436
437 @ForceInline
438 @Override
439 public void writeIndex(PoolEntry entry) {
440 writeU2(cpIndex(entry));
441 }
442
443 // Null checks entry
444 public void writeIndex(int bytecode, PoolEntry entry) {
445 writeU1U2(bytecode, cpIndex(entry));
446 }
447
448 static IllegalArgumentException invalidIndex(int idx, PoolEntry entry) {
449 return new IllegalArgumentException(idx + " is not a valid index. Entry: " + entry);
450 }
451
452 @Override
453 public void writeIndexOrZero(PoolEntry entry) {
454 writeU2(cpIndexOrZero(entry));
455 }
456
457 /**
458 * Join head and tail into an exact-size buffer
459 */
460 static byte[] join(BufWriterImpl head, BufWriterImpl tail) {
461 byte[] result = new byte[head.size() + tail.size()];
462 head.copyTo(result, 0);
463 tail.copyTo(result, head.size());
464 return result;
465 }
466 }