1 /*
2 * Copyright (c) 1997, 2019, 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 java.lang.reflect;
27
28 import java.lang.annotation.Annotation;
29 import java.lang.invoke.MethodHandle;
30 import java.lang.ref.WeakReference;
31 import java.security.AccessController;
32
33 import jdk.internal.misc.VM;
34 import jdk.internal.module.IllegalAccessLogger;
35 import jdk.internal.reflect.CallerSensitive;
36 import jdk.internal.reflect.Reflection;
37 import jdk.internal.reflect.ReflectionFactory;
38 import sun.security.action.GetPropertyAction;
39 import sun.security.util.SecurityConstants;
40
41 /**
42 * The {@code AccessibleObject} class is the base class for {@code Field},
43 * {@code Method}, and {@code Constructor} objects (known as <em>reflected
44 * objects</em>). It provides the ability to flag a reflected object as
45 * suppressing checks for Java language access control when it is used. This
46 * permits sophisticated applications with sufficient privilege, such as Java
47 * Object Serialization or other persistence mechanisms, to manipulate objects
48 * in a manner that would normally be prohibited.
49 *
50 * <p> Java language access control prevents use of private members outside
51 * their top-level class; package access members outside their package; protected members
52 * outside their package or subclasses; and public members outside their
53 * module unless they are declared in an {@link Module#isExported(String,Module)
54 * exported} package and the user {@link Module#canRead reads} their module. By
55 * default, Java language access control is enforced (with one variation) when
56 * {@code Field}s, {@code Method}s, or {@code Constructor}s are used to get or
57 * set fields, to invoke methods, or to create and initialize new instances of
58 * classes, respectively. Every reflected object checks that the code using it
59 * is in an appropriate class, package, or module. The check when invoked by
60 * <a href="{@docRoot}/../specs/jni/index.html">JNI code</a> with no Java
61 * class on the stack only succeeds if the member and the declaring class are
62 * public, and the class is in a package that is exported to all modules. </p>
63 *
64 * <p> The one variation from Java language access control is that the checks
65 * by reflected objects assume readability. That is, the module containing
66 * the use of a reflected object is assumed to read the module in which
67 * the underlying field, method, or constructor is declared. </p>
68 *
69 * <p> Whether the checks for Java language access control can be suppressed
70 * (and thus, whether access can be enabled) depends on whether the reflected
71 * object corresponds to a member in an exported or open package
72 * (see {@link #setAccessible(boolean)}). </p>
73 *
74 * @jls 6.6 Access Control
75 * @since 1.2
76 * @revised 9
77 * @spec JPMS
78 */
79 public class AccessibleObject implements AnnotatedElement {
80
81 static void checkPermission() {
82 SecurityManager sm = System.getSecurityManager();
83 if (sm != null) {
84 // SecurityConstants.ACCESS_PERMISSION is used to check
85 // whether a client has sufficient privilege to defeat Java
86 // language access control checks.
87 sm.checkPermission(SecurityConstants.ACCESS_PERMISSION);
88 }
89 }
90
91 /**
92 * Convenience method to set the {@code accessible} flag for an
93 * array of reflected objects with a single security check (for efficiency).
94 *
95 * <p> This method may be used to enable access to all reflected objects in
96 * the array when access to each reflected object can be enabled as
97 * specified by {@link #setAccessible(boolean) setAccessible(boolean)}. </p>
98 *
99 * <p>If there is a security manager, its
100 * {@code checkPermission} method is first called with a
101 * {@code ReflectPermission("suppressAccessChecks")} permission.
102 *
103 * <p>A {@code SecurityException} is also thrown if any of the elements of
104 * the input {@code array} is a {@link java.lang.reflect.Constructor}
105 * object for the class {@code java.lang.Class} and {@code flag} is true.
106 *
107 * @param array the array of AccessibleObjects
108 * @param flag the new value for the {@code accessible} flag
109 * in each object
110 * @throws InaccessibleObjectException if access cannot be enabled for all
111 * objects in the array
112 * @throws SecurityException if the request is denied by the security manager
113 * or an element in the array is a constructor for {@code
114 * java.lang.Class}
115 * @see SecurityManager#checkPermission
116 * @see ReflectPermission
117 * @revised 9
118 * @spec JPMS
119 */
120 @CallerSensitive
121 public static void setAccessible(AccessibleObject[] array, boolean flag) {
122 checkPermission();
123 if (flag) {
124 Class<?> caller = Reflection.getCallerClass();
125 array = array.clone();
126 for (AccessibleObject ao : array) {
127 ao.checkCanSetAccessible(caller);
128 }
129 }
130 for (AccessibleObject ao : array) {
131 ao.setAccessible0(flag);
132 }
133 }
134
135 /**
136 * Set the {@code accessible} flag for this reflected object to
137 * the indicated boolean value. A value of {@code true} indicates that
138 * the reflected object should suppress checks for Java language access
139 * control when it is used. A value of {@code false} indicates that
140 * the reflected object should enforce checks for Java language access
141 * control when it is used, with the variation noted in the class description.
142 *
143 * <p> This method may be used by a caller in class {@code C} to enable
144 * access to a {@link Member member} of {@link Member#getDeclaringClass()
145 * declaring class} {@code D} if any of the following hold: </p>
146 *
147 * <ul>
148 * <li> {@code C} and {@code D} are in the same module. </li>
149 *
150 * <li> The member is {@code public} and {@code D} is {@code public} in
151 * a package that the module containing {@code D} {@link
152 * Module#isExported(String,Module) exports} to at least the module
153 * containing {@code C}. </li>
154 *
155 * <li> The member is {@code protected} {@code static}, {@code D} is
156 * {@code public} in a package that the module containing {@code D}
157 * exports to at least the module containing {@code C}, and {@code C}
158 * is a subclass of {@code D}. </li>
159 *
160 * <li> {@code D} is in a package that the module containing {@code D}
161 * {@link Module#isOpen(String,Module) opens} to at least the module
162 * containing {@code C}.
163 * All packages in unnamed and open modules are open to all modules and
164 * so this method always succeeds when {@code D} is in an unnamed or
165 * open module. </li>
166 * </ul>
167 *
168 * <p> This method cannot be used to enable access to private members,
169 * members with default (package) access, protected instance members, or
170 * protected constructors when the declaring class is in a different module
171 * to the caller and the package containing the declaring class is not open
172 * to the caller's module. </p>
173 *
174 * <p> If there is a security manager, its
175 * {@code checkPermission} method is first called with a
176 * {@code ReflectPermission("suppressAccessChecks")} permission.
177 *
178 * @param flag the new value for the {@code accessible} flag
179 * @throws InaccessibleObjectException if access cannot be enabled
180 * @throws SecurityException if the request is denied by the security manager
181 * @see #trySetAccessible
182 * @see java.lang.invoke.MethodHandles#privateLookupIn
183 * @revised 9
184 * @spec JPMS
185 */
186 @CallerSensitive // overrides in Method/Field/Constructor are @CS
187 public void setAccessible(boolean flag) {
188 AccessibleObject.checkPermission();
189 setAccessible0(flag);
190 }
191
192 /**
193 * Sets the accessible flag and returns the new value
194 */
195 boolean setAccessible0(boolean flag) {
196 this.override = flag;
197 return flag;
198 }
199
200 /**
201 * Set the {@code accessible} flag for this reflected object to {@code true}
202 * if possible. This method sets the {@code accessible} flag, as if by
203 * invoking {@link #setAccessible(boolean) setAccessible(true)}, and returns
204 * the possibly-updated value for the {@code accessible} flag. If access
205 * cannot be enabled, i.e. the checks or Java language access control cannot
206 * be suppressed, this method returns {@code false} (as opposed to {@code
207 * setAccessible(true)} throwing {@code InaccessibleObjectException} when
208 * it fails).
209 *
210 * <p> This method is a no-op if the {@code accessible} flag for
211 * this reflected object is {@code true}.
212 *
213 * <p> For example, a caller can invoke {@code trySetAccessible}
214 * on a {@code Method} object for a private instance method
215 * {@code p.T::privateMethod} to suppress the checks for Java language access
216 * control when the {@code Method} is invoked.
217 * If {@code p.T} class is in a different module to the caller and
218 * package {@code p} is open to at least the caller's module,
219 * the code below successfully sets the {@code accessible} flag
220 * to {@code true}.
221 *
222 * <pre>
223 * {@code
224 * p.T obj = ....; // instance of p.T
225 * :
226 * Method m = p.T.class.getDeclaredMethod("privateMethod");
227 * if (m.trySetAccessible()) {
228 * m.invoke(obj);
229 * } else {
230 * // package p is not opened to the caller to access private member of T
231 * ...
232 * }
233 * }</pre>
234 *
235 * <p> If there is a security manager, its {@code checkPermission} method
236 * is first called with a {@code ReflectPermission("suppressAccessChecks")}
237 * permission. </p>
238 *
239 * @return {@code true} if the {@code accessible} flag is set to {@code true};
240 * {@code false} if access cannot be enabled.
241 * @throws SecurityException if the request is denied by the security manager
242 *
243 * @since 9
244 * @spec JPMS
245 * @see java.lang.invoke.MethodHandles#privateLookupIn
246 */
247 @CallerSensitive
248 public final boolean trySetAccessible() {
249 AccessibleObject.checkPermission();
250
251 if (override == true) return true;
252
253 // if it's not a Constructor, Method, Field then no access check
254 if (!Member.class.isInstance(this)) {
255 return setAccessible0(true);
256 }
257
258 // does not allow to suppress access check for Class's constructor
259 Class<?> declaringClass = ((Member) this).getDeclaringClass();
260 if (declaringClass == Class.class && this instanceof Constructor) {
261 return false;
262 }
263
264 if (checkCanSetAccessible(Reflection.getCallerClass(),
265 declaringClass,
266 false)) {
267 return setAccessible0(true);
268 } else {
269 return false;
270 }
271 }
272
273
274 /**
275 * If the given AccessibleObject is a {@code Constructor}, {@code Method}
276 * or {@code Field} then checks that its declaring class is in a package
277 * that can be accessed by the given caller of setAccessible.
278 */
279 void checkCanSetAccessible(Class<?> caller) {
280 // do nothing, needs to be overridden by Constructor, Method, Field
281 }
282
283 final void checkCanSetAccessible(Class<?> caller, Class<?> declaringClass) {
284 checkCanSetAccessible(caller, declaringClass, true);
285 }
286
287 private boolean checkCanSetAccessible(Class<?> caller,
288 Class<?> declaringClass,
289 boolean throwExceptionIfDenied) {
290 if (caller == MethodHandle.class) {
291 throw new IllegalCallerException(); // should not happen
292 }
293
294 Module callerModule = caller.getModule();
295 Module declaringModule = declaringClass.getModule();
296
297 if (callerModule == declaringModule) return true;
298 if (callerModule == Object.class.getModule()) return true;
299 if (!declaringModule.isNamed()) return true;
300
301 String pn = declaringClass.getPackageName();
302 int modifiers;
303 if (this instanceof Executable) {
304 modifiers = ((Executable) this).getModifiers();
305 } else {
306 modifiers = ((Field) this).getModifiers();
307 }
308
309 // class is public and package is exported to caller
310 boolean isClassPublic = Modifier.isPublic(declaringClass.getModifiers());
311 if (isClassPublic && declaringModule.isExported(pn, callerModule)) {
312 // member is public
313 if (Modifier.isPublic(modifiers)) {
314 logIfExportedForIllegalAccess(caller, declaringClass);
315 return true;
316 }
317
318 // member is protected-static
319 if (Modifier.isProtected(modifiers)
320 && Modifier.isStatic(modifiers)
321 && isSubclassOf(caller, declaringClass)) {
322 logIfExportedForIllegalAccess(caller, declaringClass);
323 return true;
324 }
325 }
326
327 // package is open to caller
328 if (declaringModule.isOpen(pn, callerModule)) {
329 logIfOpenedForIllegalAccess(caller, declaringClass);
330 return true;
331 }
332
333 if (throwExceptionIfDenied) {
334 // not accessible
335 String msg = "Unable to make ";
336 if (this instanceof Field)
337 msg += "field ";
338 msg += this + " accessible: " + declaringModule + " does not \"";
339 if (isClassPublic && Modifier.isPublic(modifiers))
340 msg += "exports";
341 else
342 msg += "opens";
343 msg += " " + pn + "\" to " + callerModule;
344 InaccessibleObjectException e = new InaccessibleObjectException(msg);
345 if (printStackTraceWhenAccessFails()) {
346 e.printStackTrace(System.err);
347 }
348 throw e;
349 }
350 return false;
351 }
352
353 private boolean isSubclassOf(Class<?> queryClass, Class<?> ofClass) {
354 while (queryClass != null) {
355 if (queryClass == ofClass) {
356 return true;
357 }
358 queryClass = queryClass.getSuperclass();
359 }
360 return false;
361 }
362
363 private void logIfOpenedForIllegalAccess(Class<?> caller, Class<?> declaringClass) {
364 Module callerModule = caller.getModule();
365 Module targetModule = declaringClass.getModule();
366 // callerModule is null during early startup
367 if (callerModule != null && !callerModule.isNamed() && targetModule.isNamed()) {
368 IllegalAccessLogger logger = IllegalAccessLogger.illegalAccessLogger();
369 if (logger != null) {
370 logger.logIfOpenedForIllegalAccess(caller, declaringClass, this::toShortString);
371 }
372 }
373 }
374
375 private void logIfExportedForIllegalAccess(Class<?> caller, Class<?> declaringClass) {
376 Module callerModule = caller.getModule();
377 Module targetModule = declaringClass.getModule();
378 // callerModule is null during early startup
379 if (callerModule != null && !callerModule.isNamed() && targetModule.isNamed()) {
380 IllegalAccessLogger logger = IllegalAccessLogger.illegalAccessLogger();
381 if (logger != null) {
382 logger.logIfExportedForIllegalAccess(caller, declaringClass, this::toShortString);
383 }
384 }
385 }
386
387 /**
388 * Returns a short descriptive string to describe this object in log messages.
389 */
390 String toShortString() {
391 return toString();
392 }
393
394 /**
395 * Get the value of the {@code accessible} flag for this reflected object.
396 *
397 * @return the value of the object's {@code accessible} flag
398 *
399 * @deprecated
400 * This method is deprecated because its name hints that it checks
401 * if the reflected object is accessible when it actually indicates
402 * if the checks for Java language access control are suppressed.
403 * This method may return {@code false} on a reflected object that is
404 * accessible to the caller. To test if this reflected object is accessible,
405 * it should use {@link #canAccess(Object)}.
406 *
407 * @revised 9
408 * @spec JPMS
409 */
410 @Deprecated(since="9")
411 public boolean isAccessible() {
412 return override;
413 }
414
415 /**
416 * Test if the caller can access this reflected object. If this reflected
417 * object corresponds to an instance method or field then this method tests
418 * if the caller can access the given {@code obj} with the reflected object.
419 * For instance methods or fields then the {@code obj} argument must be an
420 * instance of the {@link Member#getDeclaringClass() declaring class}. For
421 * static members and constructors then {@code obj} must be {@code null}.
422 *
423 * <p> This method returns {@code true} if the {@code accessible} flag
424 * is set to {@code true}, i.e. the checks for Java language access control
425 * are suppressed, or if the caller can access the member as
426 * specified in <cite>The Java™ Language Specification</cite>,
427 * with the variation noted in the class description. </p>
428 *
429 * @param obj an instance object of the declaring class of this reflected
430 * object if it is an instance method or field
431 *
432 * @return {@code true} if the caller can access this reflected object.
433 *
434 * @throws IllegalArgumentException
435 * <ul>
436 * <li> if this reflected object is a static member or constructor and
437 * the given {@code obj} is non-{@code null}, or </li>
438 * <li> if this reflected object is an instance method or field
439 * and the given {@code obj} is {@code null} or of type
440 * that is not a subclass of the {@link Member#getDeclaringClass()
441 * declaring class} of the member.</li>
442 * </ul>
443 *
444 * @since 9
445 * @spec JPMS
446 * @jls 6.6 Access Control
447 * @see #trySetAccessible
448 * @see #setAccessible(boolean)
449 */
450 @CallerSensitive
451 public final boolean canAccess(Object obj) {
452 if (!Member.class.isInstance(this)) {
453 return override;
454 }
455
456 Class<?> declaringClass = ((Member) this).getDeclaringClass();
457 int modifiers = ((Member) this).getModifiers();
458 if (!Modifier.isStatic(modifiers) &&
459 (this instanceof Method || this instanceof Field)) {
460 if (obj == null) {
461 throw new IllegalArgumentException("null object for " + this);
462 }
463 // if this object is an instance member, the given object
464 // must be a subclass of the declaring class of this reflected object
465 if (!declaringClass.isAssignableFrom(obj.getClass())) {
466 throw new IllegalArgumentException("object is not an instance of "
467 + declaringClass.getName());
468 }
469 } else if (obj != null) {
470 throw new IllegalArgumentException("non-null object for " + this);
471 }
472
473 // access check is suppressed
474 if (override) return true;
475
476 Class<?> caller = Reflection.getCallerClass();
477 Class<?> targetClass;
478 if (this instanceof Constructor) {
479 targetClass = declaringClass;
480 } else {
481 targetClass = Modifier.isStatic(modifiers) ? null : obj.getClass();
482 }
483 return verifyAccess(caller, declaringClass, targetClass, modifiers);
484 }
485
486 /**
487 * Constructor: only used by the Java Virtual Machine.
488 */
489 protected AccessibleObject() {}
490
491 // Indicates whether language-level access checks are overridden
492 // by this object. Initializes to "false". This field is used by
493 // Field, Method, and Constructor.
494 //
495 // NOTE: for security purposes, this field must not be visible
496 // outside this package.
497 boolean override;
498
499 // Reflection factory used by subclasses for creating field,
500 // method, and constructor accessors. Note that this is called
501 // very early in the bootstrapping process.
502 static final ReflectionFactory reflectionFactory =
503 AccessController.doPrivileged(
504 new ReflectionFactory.GetReflectionFactoryAction());
505
506 /**
507 * @throws NullPointerException {@inheritDoc}
508 * @since 1.5
509 */
510 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
511 throw new AssertionError("All subclasses should override this method");
512 }
513
514 /**
515 * {@inheritDoc}
516 * @throws NullPointerException {@inheritDoc}
517 * @since 1.5
518 */
519 @Override
520 public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
521 return AnnotatedElement.super.isAnnotationPresent(annotationClass);
522 }
523
524 /**
525 * @throws NullPointerException {@inheritDoc}
526 * @since 1.8
527 */
528 @Override
529 public <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass) {
530 throw new AssertionError("All subclasses should override this method");
531 }
532
533 /**
534 * @since 1.5
535 */
536 public Annotation[] getAnnotations() {
537 return getDeclaredAnnotations();
538 }
539
540 /**
541 * @throws NullPointerException {@inheritDoc}
542 * @since 1.8
543 */
544 @Override
545 public <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass) {
546 // Only annotations on classes are inherited, for all other
547 // objects getDeclaredAnnotation is the same as
548 // getAnnotation.
549 return getAnnotation(annotationClass);
550 }
551
552 /**
553 * @throws NullPointerException {@inheritDoc}
554 * @since 1.8
555 */
556 @Override
557 public <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass) {
558 // Only annotations on classes are inherited, for all other
559 // objects getDeclaredAnnotationsByType is the same as
560 // getAnnotationsByType.
561 return getAnnotationsByType(annotationClass);
562 }
563
564 /**
565 * @since 1.5
566 */
567 public Annotation[] getDeclaredAnnotations() {
568 throw new AssertionError("All subclasses should override this method");
569 }
570
571 // Shared access checking logic.
572
573 // For non-public members or members in package-private classes,
574 // it is necessary to perform somewhat expensive access checks.
575 // If the access check succeeds for a given class, it will
576 // always succeed (it is not affected by the granting or revoking
577 // of permissions); we speed up the check in the common case by
578 // remembering the last Class for which the check succeeded.
579 //
580 // The simple access check for Constructor is to see if
581 // the caller has already been seen, verified, and cached.
582 //
583 // A more complicated access check cache is needed for Method and Field
584 // The cache can be either null (empty cache), {caller,targetClass} pair,
585 // or a caller (with targetClass implicitly equal to memberClass).
586 // In the {caller,targetClass} case, the targetClass is always different
587 // from the memberClass.
588 volatile Object accessCheckCache;
589
590 private static class Cache {
591 final WeakReference<Class<?>> callerRef;
592 final WeakReference<Class<?>> targetRef;
593
594 Cache(Class<?> caller, Class<?> target) {
595 this.callerRef = new WeakReference<>(caller);
596 this.targetRef = new WeakReference<>(target);
597 }
598
599 boolean isCacheFor(Class<?> caller, Class<?> refc) {
600 return callerRef.get() == caller && targetRef.get() == refc;
601 }
602
603 static Object protectedMemberCallerCache(Class<?> caller, Class<?> refc) {
604 return new Cache(caller, refc);
605 }
606 }
607
608 /*
609 * Returns true if the previous access check was verified for the
610 * given caller accessing a protected member with an instance of
611 * the given targetClass where the target class is different than
612 * the declaring member class.
613 */
614 private boolean isAccessChecked(Class<?> caller, Class<?> targetClass) {
615 Object cache = accessCheckCache; // read volatile
616 if (cache instanceof Cache) {
617 return ((Cache) cache).isCacheFor(caller, targetClass);
618 }
619 return false;
620 }
621
622 /*
623 * Returns true if the previous access check was verified for the
624 * given caller accessing a static member or an instance member of
625 * the target class that is the same as the declaring member class.
626 */
627 private boolean isAccessChecked(Class<?> caller) {
628 Object cache = accessCheckCache; // read volatile
629 if (cache instanceof WeakReference) {
630 @SuppressWarnings("unchecked")
631 WeakReference<Class<?>> ref = (WeakReference<Class<?>>) cache;
632 return ref.get() == caller;
633 }
634 return false;
635 }
636
637 final void checkAccess(Class<?> caller, Class<?> memberClass,
638 Class<?> targetClass, int modifiers)
639 throws IllegalAccessException
640 {
641 if (!verifyAccess(caller, memberClass, targetClass, modifiers)) {
642 IllegalAccessException e = Reflection.newIllegalAccessException(
643 caller, memberClass, targetClass, modifiers);
644 if (printStackTraceWhenAccessFails()) {
645 e.printStackTrace(System.err);
646 }
647 throw e;
648 }
649 }
650
651 final boolean verifyAccess(Class<?> caller, Class<?> memberClass,
652 Class<?> targetClass, int modifiers)
653 {
654 if (caller == memberClass) { // quick check
655 return true; // ACCESS IS OK
656 }
657 if (targetClass != null // instance member or constructor
658 && Modifier.isProtected(modifiers)
659 && targetClass != memberClass) {
660 if (isAccessChecked(caller, targetClass)) {
661 return true; // ACCESS IS OK
662 }
663 } else if (isAccessChecked(caller)) {
664 // Non-protected case (or targetClass == memberClass or static member).
665 return true; // ACCESS IS OK
666 }
667
668 // If no return, fall through to the slow path.
669 return slowVerifyAccess(caller, memberClass, targetClass, modifiers);
670 }
671
672 // Keep all this slow stuff out of line:
673 private boolean slowVerifyAccess(Class<?> caller, Class<?> memberClass,
674 Class<?> targetClass, int modifiers)
675 {
676
677 if (caller == null) {
678 // No caller frame when a native thread attaches to the VM
679 // only allow access to a public accessible member
680 return Reflection.verifyPublicMemberAccess(memberClass, modifiers);
681 }
682
683 if (!Reflection.verifyMemberAccess(caller, memberClass, targetClass, modifiers)) {
684 // access denied
685 return false;
686 }
687
688 // access okay
689 logIfExportedForIllegalAccess(caller, memberClass);
690
691 // Success: Update the cache.
692 Object cache = (targetClass != null
693 && Modifier.isProtected(modifiers)
694 && targetClass != memberClass)
695 ? Cache.protectedMemberCallerCache(caller, targetClass)
696 : new WeakReference<>(caller);
697 accessCheckCache = cache; // write volatile
698 return true;
699 }
700
701 // true to print a stack trace when access fails
702 private static volatile boolean printStackWhenAccessFails;
703
704 // true if printStack* values are initialized
705 private static volatile boolean printStackPropertiesSet;
706
707 /**
708 * Returns true if a stack trace should be printed when access fails.
709 */
710 private static boolean printStackTraceWhenAccessFails() {
711 if (!printStackPropertiesSet && VM.initLevel() >= 1) {
712 String s = GetPropertyAction.privilegedGetProperty(
713 "sun.reflect.debugModuleAccessChecks");
714 if (s != null) {
715 printStackWhenAccessFails = !s.equalsIgnoreCase("false");
716 }
717 printStackPropertiesSet = true;
718 }
719 return printStackWhenAccessFails;
720 }
721
722 /**
723 * Returns the root AccessibleObject; or null if this object is the root.
724 *
725 * All subclasses override this method.
726 */
727 AccessibleObject getRoot() {
728 throw new InternalError();
729 }
730 }