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 try {
238 Constructor<?> cons = cl.getConstructor();
239 cons.setAccessible(true);
240 return cons;
241 } catch (NoSuchMethodException ex) {
242 return null;
243 }
244 }
245
246 public final Constructor<?> newConstructorForSerialization(Class<?> cl,
247 Constructor<?> constructorToCall)
248 {
249 if (constructorToCall.getDeclaringClass() == cl) {
250 constructorToCall.setAccessible(true);
251 return constructorToCall;
252 }
253 return generateConstructor(cl, constructorToCall);
254 }
255
256 /**
257 * Given a class, determines whether its superclass has
258 * any constructors that are accessible from the class.
259 * This is a special purpose method intended to do access
260 * checking for a serializable class and its superclasses
261 * up to, but not including, the first non-serializable
262 * superclass. This also implies that the superclass is
263 * always non-null, because a serializable class must be a
264 * class (not an interface) and Object is not serializable.
265 *
266 * @param cl the class from which access is checked
267 * @return whether the superclass has a constructor accessible from cl
268 */
269 private boolean superHasAccessibleConstructor(Class<?> cl) {
270 Class<?> superCl = cl.getSuperclass();
271 assert Serializable.class.isAssignableFrom(cl);
272 assert superCl != null;
273 if (packageEquals(cl, superCl)) {
274 // accessible if any non-private constructor is found
275 for (Constructor<?> ctor : superCl.getDeclaredConstructors()) {
276 if ((ctor.getModifiers() & Modifier.PRIVATE) == 0) {
277 return true;
278 }
279 }
280 if (Reflection.areNestMates(cl, superCl)) {
281 return true;
282 }
283 return false;
284 } else {
285 // sanity check to ensure the parent is protected or public
286 if ((superCl.getModifiers() & (Modifier.PROTECTED | Modifier.PUBLIC)) == 0) {
287 return false;
288 }
289 // accessible if any constructor is protected or public
290 for (Constructor<?> ctor : superCl.getDeclaredConstructors()) {
291 if ((ctor.getModifiers() & (Modifier.PROTECTED | Modifier.PUBLIC)) != 0) {
292 return true;
293 }
294 }
295 return false;
296 }
297 }
298
299 /**
300 * Returns a constructor that allocates an instance of cl and that then initializes
301 * the instance by calling the no-arg constructor of its first non-serializable
302 * superclass. This is specified in the Serialization Specification, section 3.1,
303 * in step 11 of the deserialization process. If cl is not serializable, returns
304 * cl's no-arg constructor. If no accessible constructor is found, or if the
305 * class hierarchy is somehow malformed (e.g., a serializable class has no
306 * superclass), null is returned.
307 *
308 * @param cl the class for which a constructor is to be found
309 * @return the generated constructor, or null if none is available
310 */
311 public final Constructor<?> newConstructorForSerialization(Class<?> cl) {
312 Class<?> initCl = cl;
313 while (Serializable.class.isAssignableFrom(initCl)) {
314 Class<?> prev = initCl;
315 if ((initCl = initCl.getSuperclass()) == null ||
316 (!disableSerialConstructorChecks() && !superHasAccessibleConstructor(prev))) {
317 return null;
318 }
319 }
320 Constructor<?> constructorToCall;
321 try {
322 constructorToCall = initCl.getDeclaredConstructor();
323 int mods = constructorToCall.getModifiers();
324 if ((mods & Modifier.PRIVATE) != 0 ||
325 ((mods & (Modifier.PUBLIC | Modifier.PROTECTED)) == 0 &&
326 !packageEquals(cl, initCl))) {
327 return null;
328 }
329 } catch (NoSuchMethodException ex) {
330 return null;
331 }
332 return generateConstructor(cl, constructorToCall);
333 }
334
335 private final Constructor<?> generateConstructor(Class<?> cl,
336 Constructor<?> constructorToCall) {
337 ConstructorAccessor acc;
338 if (useOldSerializableConstructor()) {
339 acc = new SerializationConstructorAccessorGenerator().
340 generateSerializationConstructor(cl,
341 constructorToCall.getParameterTypes(),
342 constructorToCall.getModifiers(),
343 constructorToCall.getDeclaringClass());
344 } else {
345 acc = MethodHandleAccessorFactory.newSerializableConstructorAccessor(cl, constructorToCall);
346 }
347 // Unlike other root constructors, this constructor is not copied for mutation
348 // but directly mutated, as it is not cached. To cache this constructor,
349 // setAccessible call must be done on a copy and return that copy instead.
350 Constructor<?> ctor = langReflectAccess.newConstructorWithAccessor(constructorToCall, acc);
351 ctor.setAccessible(true);
352 return ctor;
353 }
354
355 public final MethodHandle readObjectForSerialization(Class<?> cl) {
356 return findReadWriteObjectForSerialization(cl, "readObject", ObjectInputStream.class);
357 }
358
359 public final MethodHandle readObjectNoDataForSerialization(Class<?> cl) {
360 return findReadWriteObjectForSerialization(cl, "readObjectNoData", null);
361 }
362
363 public final MethodHandle writeObjectForSerialization(Class<?> cl) {
364 return findReadWriteObjectForSerialization(cl, "writeObject", ObjectOutputStream.class);
365 }
366
367 private final MethodHandle findReadWriteObjectForSerialization(Class<?> cl,
368 String methodName,
369 Class<?> streamClass) {
370 if (!Serializable.class.isAssignableFrom(cl)) {
371 return null;
372 }
373
374 try {
375 Method meth = streamClass == null ? cl.getDeclaredMethod(methodName)
376 : cl.getDeclaredMethod(methodName, streamClass);
377 int mods = meth.getModifiers();
378 if (meth.getReturnType() != Void.TYPE ||
379 Modifier.isStatic(mods) ||
380 !Modifier.isPrivate(mods)) {
381 return null;
382 }
383 meth.setAccessible(true);
384 return MethodHandles.lookup().unreflect(meth);
385 } catch (NoSuchMethodException ex) {
386 return null;
387 } catch (IllegalAccessException ex1) {
388 throw new InternalError("Error", ex1);
389 }
390 }
391
392 /**
393 * Returns a MethodHandle for {@code writeReplace} on the serializable class
394 * or null if no match found.
395 * @param cl a serializable class
396 * @return the {@code writeReplace} MethodHandle or {@code null} if not found
397 */
398 public final MethodHandle writeReplaceForSerialization(Class<?> cl) {
399 return getReplaceResolveForSerialization(cl, "writeReplace");
400 }
401
402 /**
403 * Returns a MethodHandle for {@code readResolve} on the serializable class
404 * or null if no match found.
405 * @param cl a serializable class
406 * @return the {@code writeReplace} MethodHandle or {@code null} if not found
407 */
408 public final MethodHandle readResolveForSerialization(Class<?> cl) {
409 return getReplaceResolveForSerialization(cl, "readResolve");
410 }
411
412 /**
413 * Lookup readResolve or writeReplace on a class with specified
414 * signature constraints.
415 * @param cl a serializable class
416 * @param methodName the method name to find
417 * @return a MethodHandle for the method or {@code null} if not found or
418 * has the wrong signature.
419 */
420 private MethodHandle getReplaceResolveForSerialization(Class<?> cl,
421 String methodName) {
422 if (!Serializable.class.isAssignableFrom(cl)) {
423 return null;
424 }
425
426 Class<?> defCl = cl;
427 while (defCl != null) {
428 try {
429 Method m = defCl.getDeclaredMethod(methodName);
430 if (m.getReturnType() != Object.class) {
431 return null;
432 }
433 int mods = m.getModifiers();
434 if (Modifier.isStatic(mods) | Modifier.isAbstract(mods)) {
435 return null;
436 } else if (Modifier.isPublic(mods) | Modifier.isProtected(mods)) {
437 // fall through
438 } else if (Modifier.isPrivate(mods) && (cl != defCl)) {
439 return null;
440 } else if (!packageEquals(cl, defCl)) {
441 return null;
442 }
443 try {
444 // Normal return
445 m.setAccessible(true);
446 return MethodHandles.lookup().unreflect(m);
447 } catch (IllegalAccessException ex0) {
448 // setAccessible should prevent IAE
449 throw new InternalError("Error", ex0);
450 }
451 } catch (NoSuchMethodException ex) {
452 defCl = defCl.getSuperclass();
453 }
454 }
455 return null;
456 }
457
458 /**
459 * Returns true if the given class defines a static initializer method,
460 * false otherwise.
461 */
462 public final boolean hasStaticInitializerForSerialization(Class<?> cl) {
463 Method m = hasStaticInitializerMethod;
464 if (m == null) {
465 try {
466 m = ObjectStreamClass.class.getDeclaredMethod("hasStaticInitializer",
467 new Class<?>[]{Class.class});
468 m.setAccessible(true);
469 hasStaticInitializerMethod = m;
470 } catch (NoSuchMethodException ex) {
471 throw new InternalError("No such method hasStaticInitializer on "
472 + ObjectStreamClass.class, ex);
473 }
474 }
475 try {
476 return (Boolean) m.invoke(null, cl);
477 } catch (InvocationTargetException | IllegalAccessException ex) {
478 throw new InternalError("Exception invoking hasStaticInitializer", ex);
479 }
480 }
481
482 /**
483 * Return the accessible constructor for OptionalDataException signaling eof.
484 * @return the eof constructor for OptionalDataException
485 */
486 public final Constructor<OptionalDataException> newOptionalDataExceptionForSerialization() {
487 try {
488 Constructor<OptionalDataException> boolCtor =
489 OptionalDataException.class.getDeclaredConstructor(Boolean.TYPE);
490 boolCtor.setAccessible(true);
491 return boolCtor;
492 } catch (NoSuchMethodException ex) {
493 throw new InternalError("Constructor not found", ex);
494 }
495 }
496
497 //--------------------------------------------------------------------------
498 //
499 // Internals only below this point
500 //
501
502 /*
503 * If -Djdk.reflect.useNativeAccessorOnly is set, use the native accessor only.
504 * For testing purpose only.
505 */
506 static boolean useNativeAccessorOnly() {
507 return config().useNativeAccessorOnly;
508 }
509
510 static boolean useOldSerializableConstructor() {
511 return config().useOldSerializableConstructor;
512 }
513
514 private static boolean disableSerialConstructorChecks() {
515 return config().disableSerialConstructorChecks;
516 }
517
518 /**
519 * The configuration is lazily initialized after the module system is initialized. The
520 * default config would be used before the proper config is loaded.
521 *
522 * The static initializer of ReflectionFactory is run before the system properties are set up.
523 * The class initialization is caused by the class initialization of java.lang.reflect.Method
524 * (more properly, caused by the class initialization for java.lang.reflect.AccessibleObject)
525 * that happens very early VM startup, initPhase1.
526 */
527 private static @Stable Config config;
528
529 private static final Config DEFAULT_CONFIG = new Config(false, // useNativeAccessorOnly
530 false, // useOldSerializeableConstructor
531 false); // disableSerialConstructorChecks
532
533 /**
534 * The configurations for the reflection factory. Configurable via
535 * system properties but only available after ReflectionFactory is
536 * loaded during early VM startup.
537 *
538 * Note that the default implementations of the object methods of
539 * this Config record (toString, equals, hashCode) use indy,
540 * which is available to use only after initPhase1. These methods
541 * are currently not called, but should they be needed, a workaround
542 * is to override them.
543 */
544 private record Config(boolean useNativeAccessorOnly,
545 boolean useOldSerializableConstructor,
546 boolean disableSerialConstructorChecks) {
547 }
548
549 private static Config config() {
550 Config c = config;
551 if (c != null) {
552 return c;
553 }
554
555 // Always use the default configuration until the module system is initialized.
556 if (!VM.isModuleSystemInited()) {
557 return DEFAULT_CONFIG;
558 }
559
560 return config = loadConfig();
561 }
562
563 private static Config loadConfig() {
564 assert VM.isModuleSystemInited();
565
566 Properties props = GetPropertyAction.privilegedGetProperties();
567 boolean useNativeAccessorOnly =
568 "true".equals(props.getProperty("jdk.reflect.useNativeAccessorOnly"));
569 boolean useOldSerializableConstructor =
570 "true".equals(props.getProperty("jdk.reflect.useOldSerializableConstructor"));
571 boolean disableSerialConstructorChecks =
572 "true".equals(props.getProperty("jdk.disableSerialConstructorChecks"));
573
574 return new Config(useNativeAccessorOnly, useOldSerializableConstructor, disableSerialConstructorChecks);
575 }
576
577 /**
578 * Returns true if classes are defined in the classloader and same package, false
579 * otherwise.
580 * @param cl1 a class
581 * @param cl2 another class
582 * @return true if the two classes are in the same classloader and package
583 */
584 private static boolean packageEquals(Class<?> cl1, Class<?> cl2) {
585 assert !cl1.isArray() && !cl2.isArray();
586
587 if (cl1 == cl2) {
588 return true;
589 }
590
591 return cl1.getClassLoader() == cl2.getClassLoader() &&
592 cl1.getPackageName() == cl2.getPackageName();
593 }
594
595 }