1 /*
2 * Copyright (c) 2001, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.reflect;
27
28 import java.io.Externalizable;
29 import java.io.ObjectInputStream;
30 import java.io.ObjectOutputStream;
31 import java.io.ObjectStreamClass;
32 import java.io.OptionalDataException;
33 import java.io.Serializable;
34 import java.lang.invoke.MethodHandle;
35 import java.lang.invoke.MethodHandles;
36 import java.lang.reflect.Constructor;
37 import java.lang.reflect.Executable;
38 import java.lang.reflect.Field;
39 import java.lang.reflect.InvocationTargetException;
40 import java.lang.reflect.Method;
41 import java.lang.reflect.Modifier;
42 import java.security.PrivilegedAction;
43 import java.util.Properties;
44 import jdk.internal.access.JavaLangReflectAccess;
45 import jdk.internal.access.SharedSecrets;
46 import jdk.internal.misc.VM;
47 import jdk.internal.vm.annotation.Stable;
48 import sun.security.action.GetPropertyAction;
49 import sun.security.util.SecurityConstants;
50
51 /** <P> The master factory for all reflective objects, both those in
52 java.lang.reflect (Fields, Methods, Constructors) as well as their
53 delegates (FieldAccessors, MethodAccessors, ConstructorAccessors).
54 </P>
55
56 <P> The methods in this class are extremely unsafe and can cause
57 subversion of both the language and the verifier. For this reason,
58 they are all instance methods, and access to the constructor of
59 this factory is guarded by a security check, in similar style to
60 {@link jdk.internal.misc.Unsafe}. </P>
61 */
62
63 public class ReflectionFactory {
64
65 private static final ReflectionFactory soleInstance = new ReflectionFactory();
66
67
68 /* Method for static class initializer <clinit>, or null */
69 private static volatile Method hasStaticInitializerMethod;
70
71 private final JavaLangReflectAccess langReflectAccess;
72 private ReflectionFactory() {
73 this.langReflectAccess = SharedSecrets.getJavaLangReflectAccess();
74 }
75
76 /**
77 * A convenience class for acquiring the capability to instantiate
78 * reflective objects. Use this instead of a raw call to {@link
79 * #getReflectionFactory} in order to avoid being limited by the
80 * permissions of your callers.
81 *
82 * <p>An instance of this class can be used as the argument of
83 * <code>AccessController.doPrivileged</code>.
84 */
85 public static final class GetReflectionFactoryAction
86 implements PrivilegedAction<ReflectionFactory> {
87 public ReflectionFactory run() {
88 return getReflectionFactory();
89 }
90 }
91
92 /**
93 * Provides the caller with the capability to instantiate reflective
94 * objects.
95 *
96 * <p> First, if there is a security manager, its
97 * <code>checkPermission</code> method is called with a {@link
98 * java.lang.RuntimePermission} with target
99 * <code>"reflectionFactoryAccess"</code>. This may result in a
100 * security exception.
101 *
102 * <p> The returned <code>ReflectionFactory</code> object should be
103 * carefully guarded by the caller, since it can be used to read and
104 * write private data and invoke private methods, as well as to load
105 * unverified bytecodes. It must never be passed to untrusted code.
106 *
107 * @exception SecurityException if a security manager exists and its
108 * <code>checkPermission</code> method doesn't allow
109 * access to the RuntimePermission "reflectionFactoryAccess". */
110 public static ReflectionFactory getReflectionFactory() {
111 @SuppressWarnings("removal")
112 SecurityManager security = System.getSecurityManager();
113 if (security != null) {
114 security.checkPermission(
115 SecurityConstants.REFLECTION_FACTORY_ACCESS_PERMISSION);
116 }
117 return soleInstance;
118 }
119
120 //--------------------------------------------------------------------------
121 //
122 // Routines used by java.lang.reflect
123 //
124 //
125
126 /*
127 * Note: this routine can cause the declaring class for the field
128 * be initialized and therefore must not be called until the
129 * first get/set of this field.
130 * @param field the field
131 * @param override true if caller has overridden accessibility
132 */
133 public FieldAccessor newFieldAccessor(Field field, boolean override) {
134 Field root = langReflectAccess.getRoot(field);
135 if (root != null) {
136 // FieldAccessor will use the root unless the modifiers have
137 // been overridden
138 if (root.getModifiers() == field.getModifiers() || !override) {
139 field = root;
140 }
141 }
142 boolean isFinal = Modifier.isFinal(field.getModifiers());
143 boolean isReadOnly = isFinal && (!override || langReflectAccess.isTrustedFinalField(field));
144 return MethodHandleAccessorFactory.newFieldAccessor(field, isReadOnly);
145 }
146
147 public MethodAccessor newMethodAccessor(Method method, boolean callerSensitive) {
148 // use the root Method that will not cache caller class
149 Method root = langReflectAccess.getRoot(method);
150 if (root != null) {
151 method = root;
152 }
153
154 return MethodHandleAccessorFactory.newMethodAccessor(method, callerSensitive);
155 }
156
157 public ConstructorAccessor newConstructorAccessor(Constructor<?> c) {
158 Class<?> declaringClass = c.getDeclaringClass();
159 if (Modifier.isAbstract(declaringClass.getModifiers())) {
160 return new InstantiationExceptionConstructorAccessorImpl(null);
161 }
162 if (declaringClass == Class.class) {
163 return new InstantiationExceptionConstructorAccessorImpl
164 ("Can not instantiate java.lang.Class");
165 }
166
167 // use the root Constructor that will not cache caller class
168 Constructor<?> root = langReflectAccess.getRoot(c);
169 if (root != null) {
170 c = root;
171 }
172
173 return MethodHandleAccessorFactory.newConstructorAccessor(c);
174 }
175
176 //--------------------------------------------------------------------------
177 //
178 // Routines used by java.lang
179 //
180 //
181
182 /** Makes a copy of the passed method. The returned method is a
183 "child" of the passed one; see the comments in Method.java for
184 details. */
185 public Method copyMethod(Method arg) {
186 return langReflectAccess.copyMethod(arg);
187 }
188
189 /** Makes a copy of the passed method. The returned method is NOT
190 * a "child" but a "sibling" of the Method in arg. Should only be
191 * used on non-root methods. */
192 public Method leafCopyMethod(Method arg) {
193 Method root = langReflectAccess.getRoot(arg);
194 return langReflectAccess.copyMethod(root);
195 }
196
197 /** Makes a copy of the passed field. The returned field is a
198 "child" of the passed one; see the comments in Field.java for
199 details. */
200 public Field copyField(Field arg) {
201 return langReflectAccess.copyField(arg);
202 }
203
204 /** Makes a copy of the passed constructor. The returned
205 constructor is a "child" of the passed one; see the comments
206 in Constructor.java for details. */
207 public <T> Constructor<T> copyConstructor(Constructor<T> arg) {
208 return langReflectAccess.copyConstructor(arg);
209 }
210
211 /** Gets the byte[] that encodes TypeAnnotations on an executable.
212 */
213 public byte[] getExecutableTypeAnnotationBytes(Executable ex) {
214 return langReflectAccess.getExecutableTypeAnnotationBytes(ex);
215 }
216
217 public Class<?>[] getExecutableSharedParameterTypes(Executable ex) {
218 return langReflectAccess.getExecutableSharedParameterTypes(ex);
219 }
220
221 public <T> T newInstance(Constructor<T> ctor, Object[] args, Class<?> caller)
222 throws IllegalAccessException, InstantiationException, InvocationTargetException
223 {
224 return langReflectAccess.newInstance(ctor, args, caller);
225 }
226
227 //--------------------------------------------------------------------------
228 //
229 // Routines used by serialization
230 //
231 //
232
233 public final Constructor<?> newConstructorForExternalization(Class<?> cl) {
234 if (!Externalizable.class.isAssignableFrom(cl)) {
235 return null;
236 }
237 if (cl.isValue()) {
238 throw new UnsupportedOperationException("newConstructorForExternalization does not support value classes");
239 }
240 try {
241 Constructor<?> cons = cl.getConstructor();
242 cons.setAccessible(true);
243 return cons;
244 } catch (NoSuchMethodException ex) {
245 return null;
246 }
247 }
248
249 public final Constructor<?> newConstructorForSerialization(Class<?> cl,
250 Constructor<?> constructorToCall)
251 {
252 if (constructorToCall.getDeclaringClass() == cl) {
253 constructorToCall.setAccessible(true);
254 return constructorToCall;
255 }
256 if (cl.isValue()) {
257 throw new UnsupportedOperationException("newConstructorForSerialization does not support value classes");
258 }
259 return generateConstructor(cl, constructorToCall);
260 }
261
262 /**
263 * Given a class, determines whether its superclass has
264 * any constructors that are accessible from the class.
265 * This is a special purpose method intended to do access
266 * checking for a serializable class and its superclasses
267 * up to, but not including, the first non-serializable
268 * superclass. This also implies that the superclass is
269 * always non-null, because a serializable class must be a
270 * class (not an interface) and Object is not serializable.
271 *
272 * @param cl the class from which access is checked
273 * @return whether the superclass has a constructor accessible from cl
274 */
275 private boolean superHasAccessibleConstructor(Class<?> cl) {
276 Class<?> superCl = cl.getSuperclass();
277 assert Serializable.class.isAssignableFrom(cl);
278 assert superCl != null;
279 if (packageEquals(cl, superCl)) {
280 // accessible if any non-private constructor is found
281 for (Constructor<?> ctor : superCl.getDeclaredConstructors()) {
282 if ((ctor.getModifiers() & Modifier.PRIVATE) == 0) {
283 return true;
284 }
285 }
286 if (Reflection.areNestMates(cl, superCl)) {
287 return true;
288 }
289 return false;
290 } else {
291 // sanity check to ensure the parent is protected or public
292 if ((superCl.getModifiers() & (Modifier.PROTECTED | Modifier.PUBLIC)) == 0) {
293 return false;
294 }
295 // accessible if any constructor is protected or public
296 for (Constructor<?> ctor : superCl.getDeclaredConstructors()) {
297 if ((ctor.getModifiers() & (Modifier.PROTECTED | Modifier.PUBLIC)) != 0) {
298 return true;
299 }
300 }
301 return false;
302 }
303 }
304
305 /**
306 * Returns a constructor that allocates an instance of cl and that then initializes
307 * the instance by calling the no-arg constructor of its first non-serializable
308 * superclass. This is specified in the Serialization Specification, section 3.1,
309 * in step 11 of the deserialization process. If cl is not serializable, returns
310 * cl's no-arg constructor. If no accessible constructor is found, or if the
311 * class hierarchy is somehow malformed (e.g., a serializable class has no
312 * superclass), null is returned.
313 *
314 * @param cl the class for which a constructor is to be found
315 * @return the generated constructor, or null if none is available
316 */
317 public final Constructor<?> newConstructorForSerialization(Class<?> cl) {
318 if (cl.isValue()) {
319 throw new UnsupportedOperationException("newConstructorForSerialization does not support value classes: " + cl);
320 }
321
322 Class<?> initCl = cl;
323 while (Serializable.class.isAssignableFrom(initCl)) {
324 Class<?> prev = initCl;
325 if ((initCl = initCl.getSuperclass()) == null ||
326 (!disableSerialConstructorChecks() && !superHasAccessibleConstructor(prev))) {
327 return null;
328 }
329 }
330 Constructor<?> constructorToCall;
331 try {
332 constructorToCall = initCl.getDeclaredConstructor();
333 int mods = constructorToCall.getModifiers();
334 if ((mods & Modifier.PRIVATE) != 0 ||
335 ((mods & (Modifier.PUBLIC | Modifier.PROTECTED)) == 0 &&
336 !packageEquals(cl, initCl))) {
337 return null;
338 }
339 } catch (NoSuchMethodException ex) {
340 return null;
341 }
342 return generateConstructor(cl, constructorToCall);
343 }
344
345 private final Constructor<?> generateConstructor(Class<?> cl,
346 Constructor<?> constructorToCall) {
347 ConstructorAccessor acc = MethodHandleAccessorFactory
348 .newSerializableConstructorAccessor(cl, constructorToCall);
349 // Unlike other root constructors, this constructor is not copied for mutation
350 // but directly mutated, as it is not cached. To cache this constructor,
351 // setAccessible call must be done on a copy and return that copy instead.
352 Constructor<?> ctor = langReflectAccess.newConstructorWithAccessor(constructorToCall, acc);
353 ctor.setAccessible(true);
354 return ctor;
355 }
356
357 public final MethodHandle readObjectForSerialization(Class<?> cl) {
358 return findReadWriteObjectForSerialization(cl, "readObject", ObjectInputStream.class);
359 }
360
361 public final MethodHandle readObjectNoDataForSerialization(Class<?> cl) {
362 return findReadWriteObjectForSerialization(cl, "readObjectNoData", null);
363 }
364
365 public final MethodHandle writeObjectForSerialization(Class<?> cl) {
366 return findReadWriteObjectForSerialization(cl, "writeObject", ObjectOutputStream.class);
367 }
368
369 private final MethodHandle findReadWriteObjectForSerialization(Class<?> cl,
370 String methodName,
371 Class<?> streamClass) {
372 if (!Serializable.class.isAssignableFrom(cl)) {
373 return null;
374 }
375
376 try {
377 Method meth = streamClass == null ? cl.getDeclaredMethod(methodName)
378 : cl.getDeclaredMethod(methodName, streamClass);
379 int mods = meth.getModifiers();
380 if (meth.getReturnType() != Void.TYPE ||
381 Modifier.isStatic(mods) ||
382 !Modifier.isPrivate(mods)) {
383 return null;
384 }
385 meth.setAccessible(true);
386 return MethodHandles.lookup().unreflect(meth);
387 } catch (NoSuchMethodException ex) {
388 return null;
389 } catch (IllegalAccessException ex1) {
390 throw new InternalError("Error", ex1);
391 }
392 }
393
394 /**
395 * Returns a MethodHandle for {@code writeReplace} on the serializable class
396 * or null if no match found.
397 * @param cl a serializable class
398 * @return the {@code writeReplace} MethodHandle or {@code null} if not found
399 */
400 public final MethodHandle writeReplaceForSerialization(Class<?> cl) {
401 return getReplaceResolveForSerialization(cl, "writeReplace");
402 }
403
404 /**
405 * Returns a MethodHandle for {@code readResolve} on the serializable class
406 * or null if no match found.
407 * @param cl a serializable class
408 * @return the {@code writeReplace} MethodHandle or {@code null} if not found
409 */
410 public final MethodHandle readResolveForSerialization(Class<?> cl) {
411 return getReplaceResolveForSerialization(cl, "readResolve");
412 }
413
414 /**
415 * Lookup readResolve or writeReplace on a class with specified
416 * signature constraints.
417 * @param cl a serializable class
418 * @param methodName the method name to find
419 * @return a MethodHandle for the method or {@code null} if not found or
420 * has the wrong signature.
421 */
422 private MethodHandle getReplaceResolveForSerialization(Class<?> cl,
423 String methodName) {
424 if (!Serializable.class.isAssignableFrom(cl)) {
425 return null;
426 }
427
428 Class<?> defCl = cl;
429 while (defCl != null) {
430 try {
431 Method m = defCl.getDeclaredMethod(methodName);
432 if (m.getReturnType() != Object.class) {
433 return null;
434 }
435 int mods = m.getModifiers();
436 if (Modifier.isStatic(mods) | Modifier.isAbstract(mods)) {
437 return null;
438 } else if (Modifier.isPublic(mods) | Modifier.isProtected(mods)) {
439 // fall through
440 } else if (Modifier.isPrivate(mods) && (cl != defCl)) {
441 return null;
442 } else if (!packageEquals(cl, defCl)) {
443 return null;
444 }
445 try {
446 // Normal return
447 m.setAccessible(true);
448 return MethodHandles.lookup().unreflect(m);
449 } catch (IllegalAccessException ex0) {
450 // setAccessible should prevent IAE
451 throw new InternalError("Error", ex0);
452 }
453 } catch (NoSuchMethodException ex) {
454 defCl = defCl.getSuperclass();
455 }
456 }
457 return null;
458 }
459
460 /**
461 * Returns true if the given class defines a static initializer method,
462 * false otherwise.
463 */
464 public final boolean hasStaticInitializerForSerialization(Class<?> cl) {
465 Method m = hasStaticInitializerMethod;
466 if (m == null) {
467 try {
468 m = ObjectStreamClass.class.getDeclaredMethod("hasStaticInitializer",
469 new Class<?>[]{Class.class});
470 m.setAccessible(true);
471 hasStaticInitializerMethod = m;
472 } catch (NoSuchMethodException ex) {
473 throw new InternalError("No such method hasStaticInitializer on "
474 + ObjectStreamClass.class, ex);
475 }
476 }
477 try {
478 return (Boolean) m.invoke(null, cl);
479 } catch (InvocationTargetException | IllegalAccessException ex) {
480 throw new InternalError("Exception invoking hasStaticInitializer", ex);
481 }
482 }
483
484 /**
485 * Return the accessible constructor for OptionalDataException signaling eof.
486 * @return the eof constructor for OptionalDataException
487 */
488 public final Constructor<OptionalDataException> newOptionalDataExceptionForSerialization() {
489 try {
490 Constructor<OptionalDataException> boolCtor =
491 OptionalDataException.class.getDeclaredConstructor(Boolean.TYPE);
492 boolCtor.setAccessible(true);
493 return boolCtor;
494 } catch (NoSuchMethodException ex) {
495 throw new InternalError("Constructor not found", ex);
496 }
497 }
498
499 //--------------------------------------------------------------------------
500 //
501 // Internals only below this point
502 //
503
504 /*
505 * If -Djdk.reflect.useNativeAccessorOnly is set, use the native accessor only.
506 * For testing purpose only.
507 */
508 static boolean useNativeAccessorOnly() {
509 return config().useNativeAccessorOnly;
510 }
511
512 private static boolean disableSerialConstructorChecks() {
513 return config().disableSerialConstructorChecks;
514 }
515
516 /**
517 * The configuration is lazily initialized after the module system is initialized. The
518 * default config would be used before the proper config is loaded.
519 *
520 * The static initializer of ReflectionFactory is run before the system properties are set up.
521 * The class initialization is caused by the class initialization of java.lang.reflect.Method
522 * (more properly, caused by the class initialization for java.lang.reflect.AccessibleObject)
523 * that happens very early VM startup, initPhase1.
524 */
525 private static @Stable Config config;
526
527 private static final Config DEFAULT_CONFIG = new Config(false, // useNativeAccessorOnly
528 false); // disableSerialConstructorChecks
529
530 /**
531 * The configurations for the reflection factory. Configurable via
532 * system properties but only available after ReflectionFactory is
533 * loaded during early VM startup.
534 *
535 * Note that the default implementations of the object methods of
536 * this Config record (toString, equals, hashCode) use indy,
537 * which is available to use only after initPhase1. These methods
538 * are currently not called, but should they be needed, a workaround
539 * is to override them.
540 */
541 private record Config(boolean useNativeAccessorOnly,
542 boolean disableSerialConstructorChecks) {
543 }
544
545 private static Config config() {
546 Config c = config;
547 if (c != null) {
548 return c;
549 }
550
551 // Always use the default configuration until the module system is initialized.
552 if (!VM.isModuleSystemInited()) {
553 return DEFAULT_CONFIG;
554 }
555
556 return config = loadConfig();
557 }
558
559 private static Config loadConfig() {
560 assert VM.isModuleSystemInited();
561
562 Properties props = GetPropertyAction.privilegedGetProperties();
563 boolean useNativeAccessorOnly =
564 "true".equals(props.getProperty("jdk.reflect.useNativeAccessorOnly"));
565 boolean disableSerialConstructorChecks =
566 "true".equals(props.getProperty("jdk.disableSerialConstructorChecks"));
567
568 return new Config(useNativeAccessorOnly, disableSerialConstructorChecks);
569 }
570
571 /**
572 * Returns true if classes are defined in the classloader and same package, false
573 * otherwise.
574 * @param cl1 a class
575 * @param cl2 another class
576 * @return true if the two classes are in the same classloader and package
577 */
578 private static boolean packageEquals(Class<?> cl1, Class<?> cl2) {
579 assert !cl1.isArray() && !cl2.isArray();
580
581 if (cl1 == cl2) {
582 return true;
583 }
584
585 return cl1.getClassLoader() == cl2.getClassLoader() &&
586 cl1.getPackageName() == cl2.getPackageName();
587 }
588
589 }