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 = MethodHandleAccessorFactory
338 .newSerializableConstructorAccessor(cl, constructorToCall);
339 // Unlike other root constructors, this constructor is not copied for mutation
340 // but directly mutated, as it is not cached. To cache this constructor,
341 // setAccessible call must be done on a copy and return that copy instead.
342 Constructor<?> ctor = langReflectAccess.newConstructorWithAccessor(constructorToCall, acc);
343 ctor.setAccessible(true);
344 return ctor;
345 }
346
347 public final MethodHandle readObjectForSerialization(Class<?> cl) {
348 return findReadWriteObjectForSerialization(cl, "readObject", ObjectInputStream.class);
349 }
350
351 public final MethodHandle readObjectNoDataForSerialization(Class<?> cl) {
352 return findReadWriteObjectForSerialization(cl, "readObjectNoData", null);
353 }
354
355 public final MethodHandle writeObjectForSerialization(Class<?> cl) {
356 return findReadWriteObjectForSerialization(cl, "writeObject", ObjectOutputStream.class);
357 }
358
359 private final MethodHandle findReadWriteObjectForSerialization(Class<?> cl,
360 String methodName,
361 Class<?> streamClass) {
362 if (!Serializable.class.isAssignableFrom(cl)) {
363 return null;
364 }
365
366 try {
367 Method meth = streamClass == null ? cl.getDeclaredMethod(methodName)
368 : cl.getDeclaredMethod(methodName, streamClass);
369 int mods = meth.getModifiers();
370 if (meth.getReturnType() != Void.TYPE ||
371 Modifier.isStatic(mods) ||
372 !Modifier.isPrivate(mods)) {
373 return null;
374 }
375 meth.setAccessible(true);
376 return MethodHandles.lookup().unreflect(meth);
377 } catch (NoSuchMethodException ex) {
378 return null;
379 } catch (IllegalAccessException ex1) {
380 throw new InternalError("Error", ex1);
381 }
382 }
383
384 /**
385 * Returns a MethodHandle for {@code writeReplace} on the serializable class
386 * or null if no match found.
387 * @param cl a serializable class
388 * @return the {@code writeReplace} MethodHandle or {@code null} if not found
389 */
390 public final MethodHandle writeReplaceForSerialization(Class<?> cl) {
391 return getReplaceResolveForSerialization(cl, "writeReplace");
392 }
393
394 /**
395 * Returns a MethodHandle for {@code readResolve} 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 readResolveForSerialization(Class<?> cl) {
401 return getReplaceResolveForSerialization(cl, "readResolve");
402 }
403
404 /**
405 * Lookup readResolve or writeReplace on a class with specified
406 * signature constraints.
407 * @param cl a serializable class
408 * @param methodName the method name to find
409 * @return a MethodHandle for the method or {@code null} if not found or
410 * has the wrong signature.
411 */
412 private MethodHandle getReplaceResolveForSerialization(Class<?> cl,
413 String methodName) {
414 if (!Serializable.class.isAssignableFrom(cl)) {
415 return null;
416 }
417
418 Class<?> defCl = cl;
419 while (defCl != null) {
420 try {
421 Method m = defCl.getDeclaredMethod(methodName);
422 if (m.getReturnType() != Object.class) {
423 return null;
424 }
425 int mods = m.getModifiers();
426 if (Modifier.isStatic(mods) | Modifier.isAbstract(mods)) {
427 return null;
428 } else if (Modifier.isPublic(mods) | Modifier.isProtected(mods)) {
429 // fall through
430 } else if (Modifier.isPrivate(mods) && (cl != defCl)) {
431 return null;
432 } else if (!packageEquals(cl, defCl)) {
433 return null;
434 }
435 try {
436 // Normal return
437 m.setAccessible(true);
438 return MethodHandles.lookup().unreflect(m);
439 } catch (IllegalAccessException ex0) {
440 // setAccessible should prevent IAE
441 throw new InternalError("Error", ex0);
442 }
443 } catch (NoSuchMethodException ex) {
444 defCl = defCl.getSuperclass();
445 }
446 }
447 return null;
448 }
449
450 /**
451 * Returns true if the given class defines a static initializer method,
452 * false otherwise.
453 */
454 public final boolean hasStaticInitializerForSerialization(Class<?> cl) {
455 Method m = hasStaticInitializerMethod;
456 if (m == null) {
457 try {
458 m = ObjectStreamClass.class.getDeclaredMethod("hasStaticInitializer",
459 new Class<?>[]{Class.class});
460 m.setAccessible(true);
461 hasStaticInitializerMethod = m;
462 } catch (NoSuchMethodException ex) {
463 throw new InternalError("No such method hasStaticInitializer on "
464 + ObjectStreamClass.class, ex);
465 }
466 }
467 try {
468 return (Boolean) m.invoke(null, cl);
469 } catch (InvocationTargetException | IllegalAccessException ex) {
470 throw new InternalError("Exception invoking hasStaticInitializer", ex);
471 }
472 }
473
474 /**
475 * Return the accessible constructor for OptionalDataException signaling eof.
476 * @return the eof constructor for OptionalDataException
477 */
478 public final Constructor<OptionalDataException> newOptionalDataExceptionForSerialization() {
479 try {
480 Constructor<OptionalDataException> boolCtor =
481 OptionalDataException.class.getDeclaredConstructor(Boolean.TYPE);
482 boolCtor.setAccessible(true);
483 return boolCtor;
484 } catch (NoSuchMethodException ex) {
485 throw new InternalError("Constructor not found", ex);
486 }
487 }
488
489 //--------------------------------------------------------------------------
490 //
491 // Internals only below this point
492 //
493
494 /*
495 * If -Djdk.reflect.useNativeAccessorOnly is set, use the native accessor only.
496 * For testing purpose only.
497 */
498 static boolean useNativeAccessorOnly() {
499 return config().useNativeAccessorOnly;
500 }
501
502 private static boolean disableSerialConstructorChecks() {
503 return config().disableSerialConstructorChecks;
504 }
505
506 /**
507 * The configuration is lazily initialized after the module system is initialized. The
508 * default config would be used before the proper config is loaded.
509 *
510 * The static initializer of ReflectionFactory is run before the system properties are set up.
511 * The class initialization is caused by the class initialization of java.lang.reflect.Method
512 * (more properly, caused by the class initialization for java.lang.reflect.AccessibleObject)
513 * that happens very early VM startup, initPhase1.
514 */
515 private static @Stable Config config;
516
517 private static final Config DEFAULT_CONFIG = new Config(false, // useNativeAccessorOnly
518 false); // disableSerialConstructorChecks
519
520 /**
521 * The configurations for the reflection factory. Configurable via
522 * system properties but only available after ReflectionFactory is
523 * loaded during early VM startup.
524 *
525 * Note that the default implementations of the object methods of
526 * this Config record (toString, equals, hashCode) use indy,
527 * which is available to use only after initPhase1. These methods
528 * are currently not called, but should they be needed, a workaround
529 * is to override them.
530 */
531 private record Config(boolean useNativeAccessorOnly,
532 boolean disableSerialConstructorChecks) {
533 }
534
535 private static Config config() {
536 Config c = config;
537 if (c != null) {
538 return c;
539 }
540
541 // Always use the default configuration until the module system is initialized.
542 if (!VM.isModuleSystemInited()) {
543 return DEFAULT_CONFIG;
544 }
545
546 return config = loadConfig();
547 }
548
549 private static Config loadConfig() {
550 assert VM.isModuleSystemInited();
551
552 Properties props = GetPropertyAction.privilegedGetProperties();
553 boolean useNativeAccessorOnly =
554 "true".equals(props.getProperty("jdk.reflect.useNativeAccessorOnly"));
555 boolean disableSerialConstructorChecks =
556 "true".equals(props.getProperty("jdk.disableSerialConstructorChecks"));
557
558 return new Config(useNativeAccessorOnly, disableSerialConstructorChecks);
559 }
560
561 /**
562 * Returns true if classes are defined in the classloader and same package, false
563 * otherwise.
564 * @param cl1 a class
565 * @param cl2 another class
566 * @return true if the two classes are in the same classloader and package
567 */
568 private static boolean packageEquals(Class<?> cl1, Class<?> cl2) {
569 assert !cl1.isArray() && !cl2.isArray();
570
571 if (cl1 == cl2) {
572 return true;
573 }
574
575 return cl1.getClassLoader() == cl2.getClassLoader() &&
576 cl1.getPackageName() == cl2.getPackageName();
577 }
578
579 }