1 /*
2 * Copyright (c) 1999, 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 java.lang.reflect;
27
28 import java.lang.invoke.MethodHandle;
29 import java.lang.invoke.MethodHandles;
30 import java.lang.invoke.MethodType;
31 import java.lang.invoke.WrongMethodTypeException;
32 import java.lang.module.ModuleDescriptor;
33 import java.util.ArrayDeque;
34 import java.util.ArrayList;
35 import java.util.Arrays;
36 import java.util.Collections;
37 import java.util.Deque;
38 import java.util.HashMap;
39 import java.util.HashSet;
40 import java.util.IdentityHashMap;
41 import java.util.List;
42 import java.util.Map;
43 import java.util.Objects;
44 import java.util.Set;
45 import java.util.concurrent.ConcurrentHashMap;
46 import java.util.concurrent.atomic.AtomicInteger;
47 import java.util.concurrent.atomic.AtomicLong;
48 import java.util.function.BooleanSupplier;
49
50 import jdk.internal.access.JavaLangAccess;
51 import jdk.internal.access.SharedSecrets;
52 import jdk.internal.module.Modules;
53 import jdk.internal.misc.VM;
54 import jdk.internal.misc.CDS;
55 import jdk.internal.loader.ClassLoaderValue;
56 import jdk.internal.vm.annotation.Stable;
57
58 import static java.lang.invoke.MethodType.methodType;
59 import static java.lang.module.ModuleDescriptor.Modifier.SYNTHETIC;
60
61 /**
62 *
63 * {@code Proxy} provides static methods for creating objects that act like instances
64 * of interfaces but allow for customized method invocation.
65 * To create a proxy instance for some interface {@code Foo}:
66 * <pre>{@code
67 * InvocationHandler handler = new MyInvocationHandler(...);
68 * Foo f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
69 * new Class<?>[] { Foo.class },
70 * handler);
71 * }</pre>
72 *
73 * <p>
74 * A <em>proxy class</em> is a class created at runtime that implements a specified
75 * list of interfaces, known as <em>proxy interfaces</em>. A <em>proxy instance</em>
76 * is an instance of a proxy class.
77 *
78 * Each proxy instance has an associated <i>invocation handler</i>
79 * object, which implements the interface {@link InvocationHandler}.
80 * A method invocation on a proxy instance through one of its proxy
81 * interfaces will be dispatched to the {@link InvocationHandler#invoke
82 * invoke} method of the instance's invocation handler, passing the proxy
83 * instance, a {@code java.lang.reflect.Method} object identifying
84 * the method that was invoked, and an array of type {@code Object}
85 * containing the arguments. The invocation handler processes the
86 * encoded method invocation as appropriate and the result that it
87 * returns will be returned as the result of the method invocation on
88 * the proxy instance.
89 *
90 * <p>A proxy class has the following properties:
91 *
92 * <ul>
93 * <li>The unqualified name of a proxy class is unspecified. The space
94 * of class names that begin with the string {@code "$Proxy"}
95 * should be, however, reserved for proxy classes.
96 *
97 * <li>The package and module in which a proxy class is defined is specified
98 * <a href="#membership">below</a>.
99 *
100 * <li>A proxy class is <em>final and non-abstract</em>.
101 *
102 * <li>A proxy class extends {@code java.lang.reflect.Proxy}.
103 *
104 * <li>A proxy class implements exactly the interfaces specified at its
105 * creation, in the same order. Invoking {@link Class#getInterfaces() getInterfaces}
106 * on its {@code Class} object will return an array containing the same
107 * list of interfaces (in the order specified at its creation), invoking
108 * {@link Class#getMethods getMethods} on its {@code Class} object will return
109 * an array of {@code Method} objects that include all of the
110 * methods in those interfaces, and invoking {@code getMethod} will
111 * find methods in the proxy interfaces as would be expected.
112 *
113 * <li>The {@link java.security.ProtectionDomain} of a proxy class
114 * is the same as that of system classes loaded by the bootstrap class
115 * loader, such as {@code java.lang.Object}.
116 *
117 * <li>The {@link Proxy#isProxyClass Proxy.isProxyClass} method can be used
118 * to determine if a given class is a proxy class.
119 * </ul>
120 *
121 * <p>A proxy instance has the following properties:
122 *
123 * <ul>
124 * <li>Given a proxy instance {@code proxy} and one of the
125 * interfaces, {@code Foo}, implemented by its proxy class, the
126 * following expression will return true:
127 * <pre>
128 * {@code proxy instanceof Foo}
129 * </pre>
130 * and the following cast operation will succeed (rather than throwing
131 * a {@code ClassCastException}):
132 * <pre>
133 * {@code (Foo) proxy}
134 * </pre>
135 *
136 * <li>Each proxy instance has an associated invocation handler, the one
137 * that was passed to its constructor. The static
138 * {@link Proxy#getInvocationHandler Proxy.getInvocationHandler} method
139 * will return the invocation handler associated with the proxy instance
140 * passed as its argument.
141 *
142 * <li>An interface method invocation on a proxy instance will be
143 * encoded and dispatched to the invocation handler's {@link
144 * InvocationHandler#invoke invoke} method as described in the
145 * documentation for that method.
146 *
147 * <li>A proxy interface may define a default method or inherit
148 * a default method from its superinterface directly or indirectly.
149 * An invocation handler can invoke a default method of a proxy interface
150 * by calling {@link InvocationHandler#invokeDefault(Object, Method, Object...)
151 * InvocationHandler::invokeDefault}.
152 *
153 * <li>An invocation of the {@code hashCode},
154 * {@code equals}, or {@code toString} methods declared in
155 * {@code java.lang.Object} on a proxy instance will be encoded and
156 * dispatched to the invocation handler's {@code invoke} method in
157 * the same manner as interface method invocations are encoded and
158 * dispatched, as described above. The declaring class of the
159 * {@code Method} object passed to {@code invoke} will be
160 * {@code java.lang.Object}. Other public methods of a proxy
161 * instance inherited from {@code java.lang.Object} are not
162 * overridden by a proxy class, so invocations of those methods behave
163 * like they do for instances of {@code java.lang.Object}.
164 * </ul>
165 *
166 * <h2><a id="membership">Package and Module Membership of Proxy Class</a></h2>
167 *
168 * The package and module to which a proxy class belongs are chosen such that
169 * the accessibility of the proxy class is in line with the accessibility of
170 * the proxy interfaces. Specifically, the package and the module membership
171 * of a proxy class defined via the
172 * {@link Proxy#getProxyClass(ClassLoader, Class[])} or
173 * {@link Proxy#newProxyInstance(ClassLoader, Class[], InvocationHandler)}
174 * methods is specified as follows:
175 *
176 * <ol>
177 * <li>If all the proxy interfaces are in <em>exported</em> or <em>open</em>
178 * packages:
179 * <ol type="a">
180 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
181 * <em>public</em> in an unconditionally exported but non-open package.
182 * The name of the package and the module are unspecified.</li>
183 *
184 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
185 * the proxy class is <em>non-public</em> in the package and module of the
186 * non-public interfaces. All the non-public interfaces must be in the same
187 * package and module; otherwise, proxying them is
188 * <a href="#restrictions">not possible</a>.</li>
189 * </ol>
190 * </li>
191 * <li>If at least one proxy interface is in a package that is
192 * <em>non-exported</em> and <em>non-open</em>:
193 * <ol type="a">
194 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
195 * <em>public</em> in a <em>non-exported</em>, <em>non-open</em> package of
196 * <a href="#dynamicmodule"><em>dynamic module</em>.</a>
197 * The names of the package and the module are unspecified.</li>
198 *
199 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
200 * the proxy class is <em>non-public</em> in the package and module of the
201 * non-public interfaces. All the non-public interfaces must be in the same
202 * package and module; otherwise, proxying them is
203 * <a href="#restrictions">not possible</a>.</li>
204 * </ol>
205 * </li>
206 * </ol>
207 *
208 * <p>
209 * Note that if proxy interfaces with a mix of accessibilities -- for example,
210 * an exported public interface and a non-exported non-public interface -- are
211 * proxied by the same instance, then the proxy class's accessibility is
212 * governed by the least accessible proxy interface.
213 * <p>
214 * Note that it is possible for arbitrary code to obtain access to a proxy class
215 * in an open package with {@link AccessibleObject#setAccessible setAccessible},
216 * whereas a proxy class in a non-open package is never accessible to
217 * code outside the module of the proxy class.
218 *
219 * <p>
220 * Throughout this specification, a "non-exported package" refers to a package
221 * that is not exported to all modules, and a "non-open package" refers to
222 * a package that is not open to all modules. Specifically, these terms refer to
223 * a package that either is not exported/open by its containing module or is
224 * exported/open in a qualified fashion by its containing module.
225 *
226 * <h3><a id="dynamicmodule">Dynamic Modules</a></h3>
227 * <p>
228 * A dynamic module is a named module generated at runtime. A proxy class
229 * defined in a dynamic module is encapsulated and not accessible to any module.
230 * Calling {@link Constructor#newInstance(Object...)} on a proxy class in
231 * a dynamic module will throw {@code IllegalAccessException};
232 * {@code Proxy.newProxyInstance} method should be used instead.
233 *
234 * <p>
235 * A dynamic module can read the modules of all of the superinterfaces of a proxy
236 * class and the modules of the classes and interfaces referenced by
237 * all public method signatures of a proxy class. If a superinterface or
238 * a referenced class or interface, say {@code T}, is in a non-exported package,
239 * the {@linkplain Module module} of {@code T} is updated to export the
240 * package of {@code T} to the dynamic module.
241 *
242 * <h3>Methods Duplicated in Multiple Proxy Interfaces</h3>
243 *
244 * <p>When two or more proxy interfaces contain a method with
245 * the same name and parameter signature, the order of the proxy class's
246 * interfaces becomes significant. When such a <i>duplicate method</i>
247 * is invoked on a proxy instance, the {@code Method} object passed
248 * to the invocation handler will not necessarily be the one whose
249 * declaring class is assignable from the reference type of the interface
250 * that the proxy's method was invoked through. This limitation exists
251 * because the corresponding method implementation in the generated proxy
252 * class cannot determine which interface it was invoked through.
253 * Therefore, when a duplicate method is invoked on a proxy instance,
254 * the {@code Method} object for the method in the foremost interface
255 * that contains the method (either directly or inherited through a
256 * superinterface) in the proxy class's list of interfaces is passed to
257 * the invocation handler's {@code invoke} method, regardless of the
258 * reference type through which the method invocation occurred.
259 *
260 * <p>If a proxy interface contains a method with the same name and
261 * parameter signature as the {@code hashCode}, {@code equals},
262 * or {@code toString} methods of {@code java.lang.Object},
263 * when such a method is invoked on a proxy instance, the
264 * {@code Method} object passed to the invocation handler will have
265 * {@code java.lang.Object} as its declaring class. In other words,
266 * the public, non-final methods of {@code java.lang.Object}
267 * logically precede all of the proxy interfaces for the determination of
268 * which {@code Method} object to pass to the invocation handler.
269 *
270 * <p>Note also that when a duplicate method is dispatched to an
271 * invocation handler, the {@code invoke} method may only throw
272 * checked exception types that are assignable to one of the exception
273 * types in the {@code throws} clause of the method in <i>all</i> of
274 * the proxy interfaces that it can be invoked through. If the
275 * {@code invoke} method throws a checked exception that is not
276 * assignable to any of the exception types declared by the method in one
277 * of the proxy interfaces that it can be invoked through, then an
278 * unchecked {@code UndeclaredThrowableException} will be thrown by
279 * the invocation on the proxy instance. This restriction means that not
280 * all of the exception types returned by invoking
281 * {@code getExceptionTypes} on the {@code Method} object
282 * passed to the {@code invoke} method can necessarily be thrown
283 * successfully by the {@code invoke} method.
284 *
285 * @author Peter Jones
286 * @see InvocationHandler
287 * @since 1.3
288 */
289 public class Proxy implements java.io.Serializable {
290 @java.io.Serial
291 private static final long serialVersionUID = -2222568056686623797L;
292
293 /** parameter types of a proxy class constructor */
294 private static final Class<?>[] constructorParams =
295 { InvocationHandler.class };
296
297 /**
298 * a cache of proxy constructors with
299 * {@link Constructor#setAccessible(boolean) accessible} flag already set
300 */
301 private static final ClassLoaderValue<Constructor<?>> proxyCache =
302 new ClassLoaderValue<>();
303
304 /**
305 * the invocation handler for this proxy instance.
306 * @serial
307 */
308 @SuppressWarnings("serial") // Not statically typed as Serializable
309 protected InvocationHandler h;
310
311 /**
312 * Prohibits instantiation.
313 */
314 private Proxy() {
315 }
316
317 /**
318 * Constructs a new {@code Proxy} instance from a subclass
319 * (typically, a dynamic proxy class) with the specified value
320 * for its invocation handler.
321 *
322 * @param h the invocation handler for this proxy instance
323 *
324 * @throws NullPointerException if the given invocation handler, {@code h},
325 * is {@code null}.
326 */
327 protected Proxy(InvocationHandler h) {
328 Objects.requireNonNull(h);
329 this.h = h;
330 }
331
332 /**
333 * Returns the {@code java.lang.Class} object for a proxy class
334 * given a class loader and an array of interfaces. The proxy class
335 * will be defined by the specified class loader and will implement
336 * all of the supplied interfaces. If any of the given interfaces
337 * is non-public, the proxy class will be non-public. If a proxy class
338 * for the same permutation of interfaces has already been defined by the
339 * class loader, then the existing proxy class will be returned; otherwise,
340 * a proxy class for those interfaces will be generated dynamically
341 * and defined by the class loader.
342 *
343 * @param loader the class loader to define the proxy class
344 * @param interfaces the list of interfaces for the proxy class
345 * to implement
346 * @return a proxy class that is defined in the specified class loader
347 * and that implements the specified interfaces
348 * @throws IllegalArgumentException if any of the <a href="#restrictions">
349 * restrictions</a> on the parameters are violated
350 * @throws NullPointerException if the {@code interfaces} array
351 * argument or any of its elements are {@code null}
352 *
353 * @deprecated Proxy classes generated in a named module are encapsulated
354 * and not accessible to code outside its module.
355 * {@link Constructor#newInstance(Object...) Constructor.newInstance}
356 * will throw {@code IllegalAccessException} when it is called on
357 * an inaccessible proxy class.
358 * Use {@link #newProxyInstance(ClassLoader, Class[], InvocationHandler)}
359 * to create a proxy instance instead.
360 *
361 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
362 */
363 @Deprecated
364 public static Class<?> getProxyClass(ClassLoader loader,
365 Class<?>... interfaces)
366 throws IllegalArgumentException
367 {
368 return getProxyConstructor(loader, interfaces)
369 .getDeclaringClass();
370 }
371
372 /**
373 * Returns the {@code Constructor} object of a proxy class that takes a
374 * single argument of type {@link InvocationHandler}, given a class loader
375 * and an array of interfaces. The returned constructor will have the
376 * {@link Constructor#setAccessible(boolean) accessible} flag already set.
377 *
378 * @param loader the class loader to define the proxy class
379 * @param interfaces the list of interfaces for the proxy class
380 * to implement
381 * @return a Constructor of the proxy class taking single
382 * {@code InvocationHandler} parameter
383 */
384 private static Constructor<?> getProxyConstructor(ClassLoader loader,
385 Class<?>... interfaces)
386 {
387 // optimization for single interface
388 if (interfaces.length == 1) {
389 Class<?> intf = interfaces[0];
390 return proxyCache.sub(intf).computeIfAbsent(
391 loader,
392 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
393 );
394 } else {
395 // interfaces cloned
396 final Class<?>[] intfsArray = interfaces.clone();
397 final List<Class<?>> intfs = Arrays.asList(intfsArray);
398 return proxyCache.sub(intfs).computeIfAbsent(
399 loader,
400 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
401 );
402 }
403 }
404
405 /**
406 * Called from VM native code during dump time.
407 */
408 private static void initCacheForCDS(ClassLoader platformLoader, ClassLoader appLoader) {
409 ProxyBuilder.initCacheForCDS(platformLoader, appLoader);
410 }
411
412 /**
413 * Builder for a proxy class.
414 *
415 * If the module is not specified in this ProxyBuilder constructor,
416 * it will map from the given loader and interfaces to the module
417 * in which the proxy class will be defined.
418 */
419 private static final class ProxyBuilder {
420 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
421
422 private static String makeProxyClassNamePrefix() {
423 // Allow unique proxy names to be used across CDS dump time and app run time.
424 if (CDS.isDumpingArchive()) {
425 if (CDS.isUsingArchive()) {
426 return "$Proxy0100"; // CDS dynamic dump
427 } else {
428 return "$Proxy0010"; // CDS static dump
429 }
430 } else {
431 return "$Proxy";
432 }
433 }
434
435 // prefix for all proxy class names
436 private static final String proxyClassNamePrefix = makeProxyClassNamePrefix();
437
438 // next number to use for generation of unique proxy class names
439 private static final AtomicLong nextUniqueNumber = new AtomicLong();
440
441 // a reverse cache of defined proxy classes
442 private static final ClassLoaderValue<Boolean> reverseProxyCache =
443 new ClassLoaderValue<>();
444
445 private record ProxyClassContext(Module module, String packageName, int accessFlags, boolean isDynamicModule) {
446 private ProxyClassContext {
447 if (module.isNamed()) {
448 if (packageName.isEmpty()) {
449 // Per JLS 7.4.2, unnamed package can only exist in unnamed modules.
450 // This means a package-private superinterface exist in the unnamed
451 // package of a named module.
452 throw new InternalError("Unnamed package cannot be added to " + module);
453 }
454
455 if (!module.getDescriptor().packages().contains(packageName)) {
456 throw new InternalError(packageName + " not exist in " + module.getName());
457 }
458
459 if (!module.isOpen(packageName, Proxy.class.getModule())) {
460 // Required for default method invocation
461 throw new InternalError(packageName + " not open to " + Proxy.class.getModule());
462 }
463 } else {
464 if (Modifier.isPublic(accessFlags)) {
465 // All proxy superinterfaces are public, must be in named dynamic module
466 throw new InternalError("public proxy in unnamed module: " + module);
467 }
468 }
469
470 if ((accessFlags & ~Modifier.PUBLIC) != 0) {
471 throw new InternalError("proxy access flags must be Modifier.PUBLIC or 0");
472 }
473 }
474 }
475
476 private static Class<?> defineProxyClass(ProxyClassContext context, List<Class<?>> interfaces) {
477 /*
478 * Choose a name for the proxy class to generate.
479 */
480 String packagePrefix = context.packageName().isEmpty()
481 ? proxyClassNamePrefix
482 : context.packageName() + "." + proxyClassNamePrefix;
483 ClassLoader loader = context.module().getClassLoader();
484 int accessFlags = context.accessFlags() | Modifier.FINAL;
485
486 if (archivedData != null) {
487 Class<?> pc = archivedData.getArchivedProxyClass(loader, packagePrefix, interfaces);
488 if (pc != null) {
489 reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
490 return pc;
491 }
492 }
493
494 long num = nextUniqueNumber.getAndIncrement();
495 String proxyName = packagePrefix + num;
496
497 trace(proxyName, context.module(), loader, interfaces);
498
499 if (CDS.isLoggingDynamicProxies() && context.isDynamicModule()) {
500 CDS.logDynamicProxy(loader, proxyName, interfaces.toArray(new Class<?>[0]), accessFlags);
501 }
502
503 /*
504 * Generate the specified proxy class.
505 */
506 byte[] proxyClassFile = ProxyGenerator.generateProxyClass(loader, proxyName, interfaces, accessFlags);
507 try {
508 Class<?> pc = JLA.defineClass(loader, proxyName, proxyClassFile,
509 null, "__dynamic_proxy__");
510 reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
511 return pc;
512 } catch (ClassFormatError e) {
513 /*
514 * A ClassFormatError here means that (barring bugs in the
515 * proxy class generation code) there was some other
516 * invalid aspect of the arguments supplied to the proxy
517 * class creation (such as virtual machine limitations
518 * exceeded).
519 */
520 throw new IllegalArgumentException(e.toString());
521 }
522 }
523
524 /**
525 * Called from VM native code to define a proxy class to be stored in archivedData.
526 */
527 private static Class<?> defineProxyClassForCDS(ClassLoader loader, String proxyName, Class<?>[] interfaces,
528 int accessFlags) {
529 ArrayList<Class<?>> list = new ArrayList<>();
530 for (Object o : interfaces) {
531 list.add((Class<?>)o);
532 }
533
534 ProxyBuilder builder = new ProxyBuilder(loader, list);
535 Constructor<?> cons = builder.build();
536 Class<?> proxyClass = cons.getDeclaringClass();
537 archivedData.putArchivedProxyClass(loader, proxyName, list, proxyClass);
538 return proxyClass;
539 }
540
541 /**
542 * Test if given class is a class defined by
543 * {@link #defineProxyClass(ProxyClassContext, List)}
544 */
545 static boolean isProxyClass(Class<?> c) {
546 return Objects.equals(reverseProxyCache.sub(c).get(c.getClassLoader()),
547 Boolean.TRUE);
548 }
549
550 private static boolean isExportedType(Class<?> c) {
551 String pn = c.getPackageName();
552 return Modifier.isPublic(c.getModifiers()) && c.getModule().isExported(pn);
553 }
554
555 private static boolean isPackagePrivateType(Class<?> c) {
556 return !Modifier.isPublic(c.getModifiers());
557 }
558
559 private static String toDetails(Class<?> c) {
560 String access = "unknown";
561 if (isExportedType(c)) {
562 access = "exported";
563 } else if (isPackagePrivateType(c)) {
564 access = "package-private";
565 } else {
566 access = "module-private";
567 }
568 ClassLoader ld = c.getClassLoader();
569 return String.format(" %s/%s %s loader %s",
570 c.getModule().getName(), c.getName(), access, ld);
571 }
572
573 static void trace(String cn,
574 Module module,
575 ClassLoader loader,
576 List<Class<?>> interfaces) {
577 if (isDebug()) {
578 System.err.format("PROXY: %s/%s defined by %s%n",
579 module.getName(), cn, loader);
580 }
581 if (isDebug("debug")) {
582 interfaces.forEach(c -> System.out.println(toDetails(c)));
583 }
584 }
585
586 private static final String DEBUG = System.getProperty("jdk.proxy.debug", "");
587
588 private static boolean isDebug() {
589 return !DEBUG.isEmpty();
590 }
591 private static boolean isDebug(String flag) {
592 return DEBUG.equals(flag);
593 }
594
595 // ProxyBuilder instance members start here....
596
597 private final List<Class<?>> interfaces;
598 private final ProxyClassContext context;
599 ProxyBuilder(ClassLoader loader, List<Class<?>> interfaces) {
600 Objects.requireNonNull(interfaces);
601 if (!VM.isModuleSystemInited()) {
602 throw new InternalError("Proxy is not supported until "
603 + "module system is fully initialized");
604 }
605 if (interfaces.size() > 65535) {
606 throw new IllegalArgumentException("interface limit exceeded: "
607 + interfaces.size());
608 }
609
610 Set<Class<?>> refTypes = referencedTypes(loader, interfaces);
611
612 // IAE if violates any restrictions specified in newProxyInstance
613 validateProxyInterfaces(loader, interfaces, refTypes);
614
615 this.interfaces = interfaces;
616 this.context = proxyClassContext(loader, interfaces, refTypes);
617 assert context.module().getClassLoader() == loader;
618 }
619
620 ProxyBuilder(ClassLoader loader, Class<?> intf) {
621 this(loader, Collections.singletonList(intf));
622 }
623
624 /**
625 * Generate a proxy class and return its proxy Constructor with
626 * accessible flag already set. If the target module does not have access
627 * to any interface types, IllegalAccessError will be thrown by the VM
628 * at defineClass time.
629 */
630 Constructor<?> build() {
631 Class<?> proxyClass = defineProxyClass(context, interfaces);
632
633 final Constructor<?> cons;
634 try {
635 cons = proxyClass.getConstructor(constructorParams);
636 } catch (NoSuchMethodException e) {
637 throw new InternalError(e.toString(), e);
638 }
639 cons.setAccessible(true);
640 return cons;
641 }
642
643 /**
644 * Validate the given proxy interfaces and the given referenced types
645 * are visible to the defining loader.
646 *
647 * @throws IllegalArgumentException if it violates the restrictions
648 * specified in {@link Proxy#newProxyInstance}
649 */
650 private static void validateProxyInterfaces(ClassLoader loader,
651 List<Class<?>> interfaces,
652 Set<Class<?>> refTypes)
653 {
654 Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.size());
655 for (Class<?> intf : interfaces) {
656 /*
657 * Verify that the Class object actually represents an
658 * interface.
659 */
660 if (!intf.isInterface()) {
661 throw new IllegalArgumentException(intf.getName() + " is not an interface");
662 }
663
664 if (intf.isHidden()) {
665 throw new IllegalArgumentException(intf.getName() + " is a hidden interface");
666 }
667
668 if (intf.isSealed()) {
669 throw new IllegalArgumentException(intf.getName() + " is a sealed interface");
670 }
671
672 /*
673 * Verify that the class loader resolves the name of this
674 * interface to the same Class object.
675 */
676 ensureVisible(loader, intf);
677
678 /*
679 * Verify that this interface is not a duplicate.
680 */
681 if (interfaceSet.put(intf, Boolean.TRUE) != null) {
682 throw new IllegalArgumentException("repeated interface: " + intf.getName());
683 }
684 }
685
686 for (Class<?> type : refTypes) {
687 ensureVisible(loader, type);
688 }
689 }
690
691 /*
692 * Returns all types referenced by all public non-static method signatures of
693 * the proxy interfaces
694 */
695 private static Set<Class<?>> referencedTypes(ClassLoader loader,
696 List<Class<?>> interfaces) {
697 var types = new HashSet<Class<?>>();
698 for (var intf : interfaces) {
699 for (Method m : intf.getMethods()) {
700 if (!Modifier.isStatic(m.getModifiers())) {
701 addElementType(types, m.getReturnType());
702 addElementTypes(types, m.getSharedParameterTypes());
703 addElementTypes(types, m.getSharedExceptionTypes());
704 }
705 }
706 }
707 return types;
708 }
709
710 private static void addElementTypes(HashSet<Class<?>> types,
711 Class<?> ... classes) {
712 for (var cls : classes) {
713 addElementType(types, cls);
714 }
715 }
716
717 private static void addElementType(HashSet<Class<?>> types,
718 Class<?> cls) {
719 var type = getElementType(cls);
720 if (!type.isPrimitive()) {
721 types.add(type);
722 }
723 }
724
725 /**
726 * Returns the context for the generated proxy class, including the
727 * module and the package it belongs to and whether it is package-private.
728 *
729 * If any of proxy interface is package-private, then the proxy class
730 * is in the same package and module as the package-private interface.
731 *
732 * If all proxy interfaces are public and in exported packages,
733 * then the proxy class is in a dynamic module in an unconditionally
734 * exported package.
735 *
736 * If all proxy interfaces are public and at least one in a non-exported
737 * package, then the proxy class is in a dynamic module in a
738 * non-exported package.
739 *
740 * The package of proxy class is open to java.base for deep reflective access.
741 *
742 * Reads edge and qualified exports are added for dynamic module to access.
743 */
744 private static ProxyClassContext proxyClassContext(ClassLoader loader,
745 List<Class<?>> interfaces,
746 Set<Class<?>> refTypes) {
747 Map<Class<?>, Module> packagePrivateTypes = new HashMap<>();
748 boolean nonExported = false;
749
750 for (Class<?> intf : interfaces) {
751 Module m = intf.getModule();
752 if (!Modifier.isPublic(intf.getModifiers())) {
753 packagePrivateTypes.put(intf, m);
754 } else {
755 if (!intf.getModule().isExported(intf.getPackageName())) {
756 // module-private types
757 nonExported = true;
758 }
759 }
760 }
761
762 if (packagePrivateTypes.size() > 0) {
763 // all package-private types must be in the same runtime package
764 // i.e. same package name and same module (named or unnamed)
765 //
766 // Configuration will fail if M1 and in M2 defined by the same loader
767 // and both have the same package p (so no need to check class loader)
768 Module targetModule = null;
769 String targetPackageName = null;
770 for (Map.Entry<Class<?>, Module> e : packagePrivateTypes.entrySet()) {
771 Class<?> intf = e.getKey();
772 Module m = e.getValue();
773 if ((targetModule != null && targetModule != m) ||
774 (targetPackageName != null && targetPackageName != intf.getPackageName())) {
775 throw new IllegalArgumentException(
776 "cannot have non-public interfaces in different packages");
777 }
778 if (m.getClassLoader() != loader) {
779 // the specified loader is not the same class loader
780 // of the non-public interface
781 throw new IllegalArgumentException(
782 "non-public interface is not defined by the given loader");
783 }
784
785 targetModule = m;
786 targetPackageName = e.getKey().getPackageName();
787 }
788
789 // validate if the target module can access all other interfaces
790 for (Class<?> intf : interfaces) {
791 Module m = intf.getModule();
792 if (m == targetModule) continue;
793
794 if (!targetModule.canRead(m) || !m.isExported(intf.getPackageName(), targetModule)) {
795 throw new IllegalArgumentException(targetModule + " can't access " + intf.getName());
796 }
797 }
798
799 // opens the package of the non-public proxy class for java.base to access
800 if (targetModule.isNamed()) {
801 Modules.addOpens(targetModule, targetPackageName, Proxy.class.getModule());
802 }
803 // return the module of the package-private interface
804 return new ProxyClassContext(targetModule, targetPackageName, 0, false);
805 }
806
807 // All proxy interfaces are public. So maps to a dynamic proxy module
808 // and add reads edge and qualified exports, if necessary
809 Module targetModule = getDynamicModule(loader);
810
811 // set up proxy class access to proxy interfaces and types
812 // referenced in the method signature
813 Set<Class<?>> types = new HashSet<>(interfaces);
814 types.addAll(refTypes);
815 for (Class<?> c : types) {
816 ensureAccess(targetModule, c);
817 }
818
819 var pkgName = nonExported ? PROXY_PACKAGE_PREFIX + '.' + targetModule.getName()
820 : targetModule.getName();
821 return new ProxyClassContext(targetModule, pkgName, Modifier.PUBLIC, true);
822 }
823
824 /*
825 * Ensure the given module can access the given class.
826 */
827 private static void ensureAccess(Module target, Class<?> c) {
828 Module m = c.getModule();
829 if (target == m) return;
830
831 // add read edge and qualified export for the target module to access
832 if (!target.canRead(m)) {
833 Modules.addReads(target, m);
834 }
835 String pn = c.getPackageName();
836 if (!m.isExported(pn, target)) {
837 Modules.addExports(m, pn, target);
838 }
839 }
840
841 /*
842 * Ensure the given class is visible to the class loader.
843 */
844 private static void ensureVisible(ClassLoader ld, Class<?> c) {
845 Class<?> type = null;
846 try {
847 type = Class.forName(c.getName(), false, ld);
848 } catch (ClassNotFoundException e) {
849 }
850 if (type != c) {
851 throw new IllegalArgumentException(c.getName() +
852 " referenced from a method is not visible from class loader: " + JLA.getLoaderNameID(ld));
853 }
854 }
855
856 private static Class<?> getElementType(Class<?> type) {
857 Class<?> e = type;
858 while (e.isArray()) {
859 e = e.getComponentType();
860 }
861 return e;
862 }
863
864 private static final ClassLoaderValue<Module> dynProxyModules =
865 new ClassLoaderValue<>();
866 private static final AtomicInteger counter = new AtomicInteger();
867
868 /*
869 * Define a dynamic module with a package named $MODULE which
870 * is unconditionally exported and another package named
871 * com.sun.proxy.$MODULE which is encapsulated.
872 *
873 * Each class loader will have one dynamic module.
874 */
875 private static Module getDynamicModule(ClassLoader loader) {
876 return dynProxyModules.computeIfAbsent(loader, (ld, clv) -> {
877 // create a dynamic module and setup module access
878 int num = counter.incrementAndGet();
879 String mn = "jdk.proxy" + num;
880 String pn = PROXY_PACKAGE_PREFIX + "." + mn;
881 ModuleDescriptor descriptor =
882 ModuleDescriptor.newModule(mn, Set.of(SYNTHETIC))
883 .packages(Set.of(pn, mn))
884 .exports(mn)
885 .build();
886 Module m = Modules.defineModule(ld, descriptor, null);
887 openDynamicModule(m);
888
889 if (CDS.isDumpingHeap() && archivedData != null) {
890 archivedData.recordModule(loader, m, num);
891 }
892 return m;
893 });
894 }
895
896 private static void openDynamicModule(Module m) {
897 String mn = m.getName();
898 String pn = PROXY_PACKAGE_PREFIX + "." + mn;
899 Modules.addReads(m, Proxy.class.getModule());
900 Modules.addExports(m, mn);
901 // java.base to create proxy instance and access its Lookup instance
902 Modules.addOpens(m, pn, Proxy.class.getModule());
903 Modules.addOpens(m, mn, Proxy.class.getModule());
904 }
905
906 static class ArchivedData {
907 static class InterfacesKey {
908 Class<?>[] intfsArray;
909 InterfacesKey(List<Class<?>> intfs) {
910 intfsArray = new Class<?>[intfs.size()];
911 for (int i = 0; i < intfs.size(); i++) {
912 intfsArray[i] = intfs.get(i);
913 }
914 }
915 @Override
916 public int hashCode() {
917 return Arrays.hashCode(intfsArray);
918 }
919 @Override
920 public boolean equals(Object other) {
921 if (other instanceof InterfacesKey) {
922 InterfacesKey o = (InterfacesKey)other;
923 int len = intfsArray.length;
924 if (len != o.intfsArray.length) {
925 return false;
926 }
927 Class<?>[] oa = o.intfsArray;
928 for (int i = 0; i < len; i++) {
929 if (intfsArray[i] != oa[i]) {
930 return false;
931 }
932 }
933 return true;
934 } else {
935 return false;
936 }
937 }
938 }
939
940 ClassLoader platformLoader;
941 ClassLoader appLoader;
942 HashMap<InterfacesKey,Class<?>> bootCache = new HashMap<>();
943 HashMap<InterfacesKey,Class<?>> platformCache = new HashMap<>();
944 HashMap<InterfacesKey,Class<?>> appCache = new HashMap<>();
945
946 Module bootModule;
947 Module platformModule;
948 Module appModule;
949 int maxNum;
950
951 ArchivedData(ClassLoader plat, ClassLoader app) {
952 platformLoader = plat;
953 appLoader = app;
954 }
955
956 HashMap<InterfacesKey,Class<?>> cacheForLoader(ClassLoader loader) {
957 if (loader == null) {
958 return bootCache;
959 } else if (loader == platformLoader) {
960 return platformCache;
961 } else if (loader == appLoader) {
962 return appCache;
963 } else {
964 return null;
965 }
966 }
967
968 void recordModule(ClassLoader loader, Module m, int num) {
969 if (loader == null) {
970 bootModule = m;
971 } else if (loader == platformLoader) {
972 platformModule = m;
973 } else if (loader == appLoader) {
974 appModule = m;
975 } else {
976 throw new UnsupportedOperationException("Class loader " + loader + " is not supported");
977 }
978 if (maxNum < num) {
979 maxNum = num;
980 }
981 }
982
983 void restore() {
984 // The info for addReads/addExports/addOpens are maintained solely inside the VM.
985 // CDS currently doesn't properly archive such info for the dynamically generated modules,
986 // so we have to recreate them at runtime.
987 //
988 // TODO -- consider improving CDS to archive the above info, so we can avoid calling openDynamicModule()
989 if (bootModule != null) {
990 Module last = dynProxyModules.putIfAbsent(null, bootModule);
991 assert last == null;
992 openDynamicModule(bootModule);
993 }
994 if (platformModule != null) {
995 Module last = dynProxyModules.putIfAbsent(platformLoader, platformModule);
996 assert last == null;
997 openDynamicModule(platformModule);
998 }
999 if (appModule != null) {
1000 Module last = dynProxyModules.putIfAbsent(appLoader, appModule);
1001 assert last == null;
1002 openDynamicModule(appModule);
1003 }
1004
1005 while (maxNum > counter.get()) {
1006 counter.incrementAndGet();
1007 }
1008 }
1009
1010
1011 Class<?> getArchivedProxyClass(ClassLoader loader, String proxyPrefix, List<Class<?>> interfaces) {
1012 HashMap<InterfacesKey,Class<?>> cache = cacheForLoader(loader);
1013 if (cache != null && cache.size() > 0) {
1014 InterfacesKey key = new InterfacesKey(interfaces);
1015 return cache.get(key);
1016 } else {
1017 return null;
1018 }
1019 }
1020
1021 void putArchivedProxyClass(ClassLoader loader, String proxyName, List<Class<?>> interfaces, Class<?> cls) {
1022 HashMap<InterfacesKey,Class<?>> cache = cacheForLoader(loader);
1023 if (cache != null) {
1024 InterfacesKey key = new InterfacesKey(interfaces);
1025 cache.put(key, cls);
1026 }
1027 }
1028 }
1029
1030 static ArchivedData archivedData;
1031
1032 static {
1033 CDS.initializeFromArchive(ProxyBuilder.class);
1034 if (archivedData != null) {
1035 archivedData.restore();
1036 }
1037 }
1038
1039 private static void initCacheForCDS(ClassLoader platformLoader, ClassLoader appLoader) {
1040 archivedData = new ArchivedData(platformLoader, appLoader);
1041 }
1042 }
1043
1044 /**
1045 * Returns a proxy instance for the specified interfaces
1046 * that dispatches method invocations to the specified invocation
1047 * handler.
1048 * <p>
1049 * <a id="restrictions">{@code IllegalArgumentException} will be thrown
1050 * if any of the following restrictions is violated:</a>
1051 * <ul>
1052 * <li>All of {@code Class} objects in the given {@code interfaces} array
1053 * must represent {@linkplain Class#isHidden() non-hidden} and
1054 * {@linkplain Class#isSealed() non-sealed} interfaces,
1055 * not classes or primitive types.
1056 *
1057 * <li>No two elements in the {@code interfaces} array may
1058 * refer to identical {@code Class} objects.
1059 *
1060 * <li>All of the interface types must be visible by name through the
1061 * specified class loader. In other words, for class loader
1062 * {@code cl} and every interface {@code i}, the following
1063 * expression must be true:<p>
1064 * {@code Class.forName(i.getName(), false, cl) == i}
1065 *
1066 * <li>All of the types referenced by all
1067 * public method signatures of the specified interfaces
1068 * and those inherited by their superinterfaces
1069 * must be visible by name through the specified class loader.
1070 *
1071 * <li>All non-public interfaces must be in the same package
1072 * and module, defined by the specified class loader and
1073 * the module of the non-public interfaces can access all of
1074 * the interface types; otherwise, it would not be possible for
1075 * the proxy class to implement all of the interfaces,
1076 * regardless of what package it is defined in.
1077 *
1078 * <li>For any set of member methods of the specified interfaces
1079 * that have the same signature:
1080 * <ul>
1081 * <li>If the return type of any of the methods is a primitive
1082 * type or void, then all of the methods must have that same
1083 * return type.
1084 * <li>Otherwise, one of the methods must have a return type that
1085 * is assignable to all of the return types of the rest of the
1086 * methods.
1087 * </ul>
1088 *
1089 * <li>The resulting proxy class must not exceed any limits imposed
1090 * on classes by the virtual machine. For example, the VM may limit
1091 * the number of interfaces that a class may implement to 65535; in
1092 * that case, the size of the {@code interfaces} array must not
1093 * exceed 65535.
1094 * </ul>
1095 *
1096 * <p>Note that the order of the specified proxy interfaces is
1097 * significant: two requests for a proxy class with the same combination
1098 * of interfaces but in a different order will result in two distinct
1099 * proxy classes.
1100 *
1101 * @param loader the class loader to define the proxy class
1102 * @param interfaces the list of interfaces for the proxy class
1103 * to implement
1104 * @param h the invocation handler to dispatch method invocations to
1105 * @return a proxy instance with the specified invocation handler of a
1106 * proxy class that is defined by the specified class loader
1107 * and that implements the specified interfaces
1108 * @throws IllegalArgumentException if any of the <a href="#restrictions">
1109 * restrictions</a> on the parameters are violated
1110 * @throws NullPointerException if the {@code interfaces} array
1111 * argument or any of its elements are {@code null}, or
1112 * if the invocation handler, {@code h}, is
1113 * {@code null}
1114 *
1115 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
1116 */
1117 public static Object newProxyInstance(ClassLoader loader,
1118 Class<?>[] interfaces,
1119 InvocationHandler h) {
1120 Objects.requireNonNull(h);
1121
1122 /*
1123 * Look up or generate the designated proxy class and its constructor.
1124 */
1125 Constructor<?> cons = getProxyConstructor(loader, interfaces);
1126
1127 return newProxyInstance(cons, h);
1128 }
1129
1130 private static Object newProxyInstance(Constructor<?> cons, InvocationHandler h) {
1131 /*
1132 * Invoke its constructor with the designated invocation handler.
1133 */
1134 try {
1135 return cons.newInstance(new Object[]{h});
1136 } catch (IllegalAccessException | InstantiationException e) {
1137 throw new InternalError(e.toString(), e);
1138 } catch (InvocationTargetException e) {
1139 Throwable t = e.getCause();
1140 if (t instanceof RuntimeException re) {
1141 throw re;
1142 } else {
1143 throw new InternalError(t.toString(), t);
1144 }
1145 }
1146 }
1147
1148 /**
1149 * Returns true if the given class is a proxy class.
1150 *
1151 * @implNote The reliability of this method is important for the ability
1152 * to use it to make security decisions, so its implementation should
1153 * not just test if the class in question extends {@code Proxy}.
1154 *
1155 * @param cl the class to test
1156 * @return {@code true} if the class is a proxy class and
1157 * {@code false} otherwise
1158 * @throws NullPointerException if {@code cl} is {@code null}
1159 */
1160 public static boolean isProxyClass(Class<?> cl) {
1161 return Proxy.class.isAssignableFrom(cl) && ProxyBuilder.isProxyClass(cl);
1162 }
1163
1164 /**
1165 * Returns the invocation handler for the specified proxy instance.
1166 *
1167 * @param proxy the proxy instance to return the invocation handler for
1168 * @return the invocation handler for the proxy instance
1169 * @throws IllegalArgumentException if the argument is not a
1170 * proxy instance
1171 */
1172 public static InvocationHandler getInvocationHandler(Object proxy)
1173 throws IllegalArgumentException
1174 {
1175 /*
1176 * Verify that the object is actually a proxy instance.
1177 */
1178 if (!isProxyClass(proxy.getClass())) {
1179 throw new IllegalArgumentException("not a proxy instance");
1180 }
1181
1182 final Proxy p = (Proxy) proxy;
1183 final InvocationHandler ih = p.h;
1184 return ih;
1185 }
1186
1187 private static final String PROXY_PACKAGE_PREFIX = "com.sun.proxy";
1188
1189 /**
1190 * A cache of Method -> MethodHandle for default methods.
1191 */
1192 private static final ClassValue<ConcurrentHashMap<Method, MethodHandle>>
1193 DEFAULT_METHODS_MAP = new ClassValue<>() {
1194 @Override
1195 protected ConcurrentHashMap<Method, MethodHandle> computeValue(Class<?> type) {
1196 return new ConcurrentHashMap<>(4);
1197 }
1198 };
1199
1200 private static ConcurrentHashMap<Method, MethodHandle> defaultMethodMap(Class<?> proxyClass) {
1201 assert isProxyClass(proxyClass);
1202 return DEFAULT_METHODS_MAP.get(proxyClass);
1203 }
1204
1205 static final Object[] EMPTY_ARGS = new Object[0];
1206
1207 static MethodHandle defaultMethodHandle(Class<? extends Proxy> proxyClass, Method method) {
1208 // lookup the cached method handle
1209 ConcurrentHashMap<Method, MethodHandle> methods = defaultMethodMap(proxyClass);
1210 MethodHandle superMH = methods.get(method);
1211 if (superMH == null) {
1212 MethodType type = methodType(method.getReturnType(), method.getParameterTypes());
1213 MethodHandles.Lookup lookup = MethodHandles.lookup();
1214 Class<?> proxyInterface = findProxyInterfaceOrElseThrow(proxyClass, method);
1215 MethodHandle dmh;
1216 try {
1217 dmh = proxyClassLookup(lookup, proxyClass)
1218 .findSpecial(proxyInterface, method.getName(), type, proxyClass)
1219 .withVarargs(false);
1220 } catch (IllegalAccessException | NoSuchMethodException e) {
1221 // should not reach here
1222 throw new InternalError(e);
1223 }
1224 // this check can be turned into assertion as it is guaranteed to succeed by the virtue of
1225 // looking up a default (instance) method declared or inherited by proxyInterface
1226 // while proxyClass implements (is a subtype of) proxyInterface ...
1227 assert ((BooleanSupplier) () -> {
1228 try {
1229 // make sure that the method type matches
1230 dmh.asType(type.insertParameterTypes(0, proxyClass));
1231 return true;
1232 } catch (WrongMethodTypeException e) {
1233 return false;
1234 }
1235 }).getAsBoolean() : "Wrong method type";
1236 // change return type to Object
1237 MethodHandle mh = dmh.asType(dmh.type().changeReturnType(Object.class));
1238 // wrap any exception thrown with InvocationTargetException
1239 mh = MethodHandles.catchException(mh, Throwable.class, InvocationException.wrapMH());
1240 // spread array of arguments among parameters (skipping 1st parameter - target)
1241 mh = mh.asSpreader(1, Object[].class, type.parameterCount());
1242 // change target type to Object
1243 mh = mh.asType(MethodType.methodType(Object.class, Object.class, Object[].class));
1244
1245 // push MH into cache
1246 MethodHandle cached = methods.putIfAbsent(method, mh);
1247 if (cached != null) {
1248 superMH = cached;
1249 } else {
1250 superMH = mh;
1251 }
1252 }
1253 return superMH;
1254 }
1255
1256 /**
1257 * Finds the first proxy interface that declares the given method
1258 * directly or indirectly.
1259 *
1260 * @throws IllegalArgumentException if not found
1261 */
1262 private static Class<?> findProxyInterfaceOrElseThrow(Class<?> proxyClass, Method method) {
1263 Class<?> declaringClass = method.getDeclaringClass();
1264 if (!declaringClass.isInterface()) {
1265 throw new IllegalArgumentException("\"" + method +
1266 "\" is not a method declared in the proxy class");
1267 }
1268
1269 List<Class<?>> proxyInterfaces = Arrays.asList(proxyClass.getInterfaces());
1270 // the method's declaring class is a proxy interface
1271 if (proxyInterfaces.contains(declaringClass))
1272 return declaringClass;
1273
1274 // find the first proxy interface that inherits the default method
1275 // i.e. the declaring class of the default method is a superinterface
1276 // of the proxy interface
1277 Deque<Class<?>> deque = new ArrayDeque<>();
1278 Set<Class<?>> visited = new HashSet<>();
1279 boolean indirectMethodRef = false;
1280 for (Class<?> proxyIntf : proxyInterfaces) {
1281 assert proxyIntf != declaringClass;
1282 visited.add(proxyIntf);
1283 deque.add(proxyIntf);
1284
1285 // for each proxy interface, traverse its subinterfaces with
1286 // breadth-first search to find a subinterface declaring the
1287 // default method
1288 Class<?> c;
1289 while ((c = deque.poll()) != null) {
1290 if (c == declaringClass) {
1291 try {
1292 // check if this method is the resolved method if referenced from
1293 // this proxy interface (i.e. this method is not implemented
1294 // by any other superinterface)
1295 Method m = proxyIntf.getMethod(method.getName(), method.getSharedParameterTypes());
1296 if (m.getDeclaringClass() == declaringClass) {
1297 return proxyIntf;
1298 }
1299 indirectMethodRef = true;
1300 } catch (NoSuchMethodException e) {}
1301
1302 // skip traversing its superinterfaces
1303 // another proxy interface may extend it and so
1304 // the method's declaring class is left unvisited.
1305 continue;
1306 }
1307 // visit all superinterfaces of one proxy interface to find if
1308 // this proxy interface inherits the method directly or indirectly
1309 visited.add(c);
1310 for (Class<?> superIntf : c.getInterfaces()) {
1311 if (!visited.contains(superIntf) && !deque.contains(superIntf)) {
1312 if (superIntf == declaringClass) {
1313 // fast-path as the matching subinterface is found
1314 deque.addFirst(superIntf);
1315 } else {
1316 deque.add(superIntf);
1317 }
1318 }
1319 }
1320 }
1321 }
1322
1323 throw new IllegalArgumentException("\"" + method + (indirectMethodRef
1324 ? "\" is overridden directly or indirectly by the proxy interfaces"
1325 : "\" is not a method declared in the proxy class"));
1326 }
1327
1328 /**
1329 * This method invokes the proxy's proxyClassLookup method to get a
1330 * Lookup on the proxy class.
1331 *
1332 * @return a lookup for proxy class of this proxy instance
1333 */
1334 private static MethodHandles.Lookup proxyClassLookup(MethodHandles.Lookup caller, Class<?> proxyClass) {
1335 try {
1336 Method m = proxyClass.getDeclaredMethod("proxyClassLookup", MethodHandles.Lookup.class);
1337 m.setAccessible(true);
1338 return (MethodHandles.Lookup) m.invoke(null, caller);
1339 } catch (ReflectiveOperationException e) {
1340 throw new InternalError(e);
1341 }
1342 }
1343
1344 /*
1345 * Invoke the default method of the given proxy with an explicit caller class.
1346 *
1347 * @throws IllegalAccessException if the proxy interface is inaccessible to the caller
1348 * if caller is non-null
1349 */
1350 static Object invokeDefault(Object proxy, Method method, Object[] args, Class<?> caller)
1351 throws Throwable {
1352 // verify that the object is actually a proxy instance
1353 if (!Proxy.isProxyClass(proxy.getClass())) {
1354 throw new IllegalArgumentException("'proxy' is not a proxy instance");
1355 }
1356 if (!method.isDefault()) {
1357 throw new IllegalArgumentException("\"" + method + "\" is not a default method");
1358 }
1359 @SuppressWarnings("unchecked")
1360 Class<? extends Proxy> proxyClass = (Class<? extends Proxy>)proxy.getClass();
1361
1362 // skip access check if caller is null
1363 if (caller != null) {
1364 Class<?> intf = method.getDeclaringClass();
1365 // access check on the default method
1366 method.checkAccess(caller, intf, proxyClass, method.getModifiers());
1367 }
1368
1369 MethodHandle mh = Proxy.defaultMethodHandle(proxyClass, method);
1370 // invoke the super method
1371 try {
1372 // the args array can be null if the number of formal parameters required by
1373 // the method is zero (consistent with Method::invoke)
1374 Object[] params = args != null ? args : Proxy.EMPTY_ARGS;
1375 return mh.invokeExact(proxy, params);
1376 } catch (ClassCastException | NullPointerException e) {
1377 throw new IllegalArgumentException(e.getMessage(), e);
1378 } catch (Proxy.InvocationException e) {
1379 // unwrap and throw the exception thrown by the default method
1380 throw e.getCause();
1381 }
1382 }
1383
1384 /**
1385 * Internal exception type to wrap the exception thrown by the default method
1386 * so that it can distinguish CCE and NPE thrown due to the arguments
1387 * incompatible with the method signature.
1388 */
1389 static class InvocationException extends ReflectiveOperationException {
1390 @java.io.Serial
1391 private static final long serialVersionUID = 0L;
1392
1393 InvocationException(Throwable cause) {
1394 super(cause);
1395 }
1396
1397 /**
1398 * Wraps given cause with InvocationException and throws it.
1399 */
1400 static Object wrap(Throwable cause) throws InvocationException {
1401 throw new InvocationException(cause);
1402 }
1403
1404 @Stable
1405 static MethodHandle wrapMethodHandle;
1406
1407 static MethodHandle wrapMH() {
1408 MethodHandle mh = wrapMethodHandle;
1409 if (mh == null) {
1410 try {
1411 wrapMethodHandle = mh = MethodHandles.lookup().findStatic(
1412 InvocationException.class,
1413 "wrap",
1414 MethodType.methodType(Object.class, Throwable.class)
1415 );
1416 } catch (NoSuchMethodException | IllegalAccessException e) {
1417 throw new InternalError(e);
1418 }
1419 }
1420 return mh;
1421 }
1422 }
1423
1424 }