1 /*
2 * Copyright (c) 1999, 2023, 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.security.AccessController;
34 import java.security.PrivilegedAction;
35 import java.util.ArrayDeque;
36 import java.util.ArrayList;
37 import java.util.Arrays;
38 import java.util.Collections;
39 import java.util.Deque;
40 import java.util.HashMap;
41 import java.util.HashSet;
42 import java.util.IdentityHashMap;
43 import java.util.List;
44 import java.util.Map;
45 import java.util.Objects;
46 import java.util.Set;
47 import java.util.concurrent.ConcurrentHashMap;
48 import java.util.concurrent.atomic.AtomicInteger;
49 import java.util.concurrent.atomic.AtomicLong;
50 import java.util.function.BooleanSupplier;
51
52 import jdk.internal.access.JavaLangAccess;
53 import jdk.internal.access.SharedSecrets;
54 import jdk.internal.module.Modules;
55 import jdk.internal.misc.VM;
56 import jdk.internal.misc.CDS;
57 import jdk.internal.reflect.CallerSensitive;
58 import jdk.internal.reflect.Reflection;
59 import jdk.internal.loader.ClassLoaderValue;
60 import jdk.internal.vm.annotation.Stable;
61 import sun.reflect.misc.ReflectUtil;
62 import sun.security.action.GetPropertyAction;
63 import sun.security.util.SecurityConstants;
64
65 import static java.lang.invoke.MethodType.methodType;
66 import static java.lang.module.ModuleDescriptor.Modifier.SYNTHETIC;
67
68 /**
69 *
70 * {@code Proxy} provides static methods for creating objects that act like instances
71 * of interfaces but allow for customized method invocation.
72 * To create a proxy instance for some interface {@code Foo}:
73 * <pre>{@code
74 * InvocationHandler handler = new MyInvocationHandler(...);
75 * Foo f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
76 * new Class<?>[] { Foo.class },
77 * handler);
78 * }</pre>
79 *
80 * <p>
81 * A <em>proxy class</em> is a class created at runtime that implements a specified
82 * list of interfaces, known as <em>proxy interfaces</em>. A <em>proxy instance</em>
83 * is an instance of a proxy class.
84 *
85 * Each proxy instance has an associated <i>invocation handler</i>
86 * object, which implements the interface {@link InvocationHandler}.
87 * A method invocation on a proxy instance through one of its proxy
88 * interfaces will be dispatched to the {@link InvocationHandler#invoke
89 * invoke} method of the instance's invocation handler, passing the proxy
90 * instance, a {@code java.lang.reflect.Method} object identifying
91 * the method that was invoked, and an array of type {@code Object}
92 * containing the arguments. The invocation handler processes the
93 * encoded method invocation as appropriate and the result that it
94 * returns will be returned as the result of the method invocation on
95 * the proxy instance.
96 *
97 * <p>A proxy class has the following properties:
98 *
99 * <ul>
100 * <li>The unqualified name of a proxy class is unspecified. The space
101 * of class names that begin with the string {@code "$Proxy"}
102 * should be, however, reserved for proxy classes.
103 *
104 * <li>The package and module in which a proxy class is defined is specified
105 * <a href="#membership">below</a>.
106 *
107 * <li>A proxy class is <em>final and non-abstract</em>.
108 *
109 * <li>A proxy class extends {@code java.lang.reflect.Proxy}.
110 *
111 * <li>A proxy class implements exactly the interfaces specified at its
112 * creation, in the same order. Invoking {@link Class#getInterfaces() getInterfaces}
113 * on its {@code Class} object will return an array containing the same
114 * list of interfaces (in the order specified at its creation), invoking
115 * {@link Class#getMethods getMethods} on its {@code Class} object will return
116 * an array of {@code Method} objects that include all of the
117 * methods in those interfaces, and invoking {@code getMethod} will
118 * find methods in the proxy interfaces as would be expected.
119 *
120 * <li>The {@link java.security.ProtectionDomain} of a proxy class
121 * is the same as that of system classes loaded by the bootstrap class
122 * loader, such as {@code java.lang.Object}, because the code for a
123 * proxy class is generated by trusted system code. This protection
124 * domain will typically be granted {@code java.security.AllPermission}.
125 *
126 * <li>The {@link Proxy#isProxyClass Proxy.isProxyClass} method can be used
127 * to determine if a given class is a proxy class.
128 * </ul>
129 *
130 * <p>A proxy instance has the following properties:
131 *
132 * <ul>
133 * <li>Given a proxy instance {@code proxy} and one of the
134 * interfaces, {@code Foo}, implemented by its proxy class, the
135 * following expression will return true:
136 * <pre>
137 * {@code proxy instanceof Foo}
138 * </pre>
139 * and the following cast operation will succeed (rather than throwing
140 * a {@code ClassCastException}):
141 * <pre>
142 * {@code (Foo) proxy}
143 * </pre>
144 *
145 * <li>Each proxy instance has an associated invocation handler, the one
146 * that was passed to its constructor. The static
147 * {@link Proxy#getInvocationHandler Proxy.getInvocationHandler} method
148 * will return the invocation handler associated with the proxy instance
149 * passed as its argument.
150 *
151 * <li>An interface method invocation on a proxy instance will be
152 * encoded and dispatched to the invocation handler's {@link
153 * InvocationHandler#invoke invoke} method as described in the
154 * documentation for that method.
155 *
156 * <li>A proxy interface may define a default method or inherit
157 * a default method from its superinterface directly or indirectly.
158 * An invocation handler can invoke a default method of a proxy interface
159 * by calling {@link InvocationHandler#invokeDefault(Object, Method, Object...)
160 * InvocationHandler::invokeDefault}.
161 *
162 * <li>An invocation of the {@code hashCode},
163 * {@code equals}, or {@code toString} methods declared in
164 * {@code java.lang.Object} on a proxy instance will be encoded and
165 * dispatched to the invocation handler's {@code invoke} method in
166 * the same manner as interface method invocations are encoded and
167 * dispatched, as described above. The declaring class of the
168 * {@code Method} object passed to {@code invoke} will be
169 * {@code java.lang.Object}. Other public methods of a proxy
170 * instance inherited from {@code java.lang.Object} are not
171 * overridden by a proxy class, so invocations of those methods behave
172 * like they do for instances of {@code java.lang.Object}.
173 * </ul>
174 *
175 * <h2><a id="membership">Package and Module Membership of Proxy Class</a></h2>
176 *
177 * The package and module to which a proxy class belongs are chosen such that
178 * the accessibility of the proxy class is in line with the accessibility of
179 * the proxy interfaces. Specifically, the package and the module membership
180 * of a proxy class defined via the
181 * {@link Proxy#getProxyClass(ClassLoader, Class[])} or
182 * {@link Proxy#newProxyInstance(ClassLoader, Class[], InvocationHandler)}
183 * methods is specified as follows:
184 *
185 * <ol>
186 * <li>If all the proxy interfaces are in <em>exported</em> or <em>open</em>
187 * packages:
188 * <ol type="a">
189 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
190 * <em>public</em> in an unconditionally exported but non-open package.
191 * The name of the package and the module are unspecified.</li>
192 *
193 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
194 * the proxy class is <em>non-public</em> in the package and module of the
195 * non-public interfaces. All the non-public interfaces must be in the same
196 * package and module; otherwise, proxying them is
197 * <a href="#restrictions">not possible</a>.</li>
198 * </ol>
199 * </li>
200 * <li>If at least one proxy interface is in a package that is
201 * <em>non-exported</em> and <em>non-open</em>:
202 * <ol type="a">
203 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
204 * <em>public</em> in a <em>non-exported</em>, <em>non-open</em> package of
205 * <a href="#dynamicmodule"><em>dynamic module</em>.</a>
206 * The names of the package and the module are unspecified.</li>
207 *
208 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
209 * the proxy class is <em>non-public</em> in the package and module of the
210 * non-public interfaces. All the non-public interfaces must be in the same
211 * package and module; otherwise, proxying them is
212 * <a href="#restrictions">not possible</a>.</li>
213 * </ol>
214 * </li>
215 * </ol>
216 *
217 * <p>
218 * Note that if proxy interfaces with a mix of accessibilities -- for example,
219 * an exported public interface and a non-exported non-public interface -- are
220 * proxied by the same instance, then the proxy class's accessibility is
221 * governed by the least accessible proxy interface.
222 * <p>
223 * Note that it is possible for arbitrary code to obtain access to a proxy class
224 * in an open package with {@link AccessibleObject#setAccessible setAccessible},
225 * whereas a proxy class in a non-open package is never accessible to
226 * code outside the module of the proxy class.
227 *
228 * <p>
229 * Throughout this specification, a "non-exported package" refers to a package
230 * that is not exported to all modules, and a "non-open package" refers to
231 * a package that is not open to all modules. Specifically, these terms refer to
232 * a package that either is not exported/open by its containing module or is
233 * exported/open in a qualified fashion by its containing module.
234 *
235 * <h3><a id="dynamicmodule">Dynamic Modules</a></h3>
236 * <p>
237 * A dynamic module is a named module generated at runtime. A proxy class
238 * defined in a dynamic module is encapsulated and not accessible to any module.
239 * Calling {@link Constructor#newInstance(Object...)} on a proxy class in
240 * a dynamic module will throw {@code IllegalAccessException};
241 * {@code Proxy.newProxyInstance} method should be used instead.
242 *
243 * <p>
244 * A dynamic module can read the modules of all of the superinterfaces of a proxy
245 * class and the modules of the classes and interfaces referenced by
246 * all public method signatures of a proxy class. If a superinterface or
247 * a referenced class or interface, say {@code T}, is in a non-exported package,
248 * the {@linkplain Module module} of {@code T} is updated to export the
249 * package of {@code T} to the dynamic module.
250 *
251 * <h3>Methods Duplicated in Multiple Proxy Interfaces</h3>
252 *
253 * <p>When two or more proxy interfaces contain a method with
254 * the same name and parameter signature, the order of the proxy class's
255 * interfaces becomes significant. When such a <i>duplicate method</i>
256 * is invoked on a proxy instance, the {@code Method} object passed
257 * to the invocation handler will not necessarily be the one whose
258 * declaring class is assignable from the reference type of the interface
259 * that the proxy's method was invoked through. This limitation exists
260 * because the corresponding method implementation in the generated proxy
261 * class cannot determine which interface it was invoked through.
262 * Therefore, when a duplicate method is invoked on a proxy instance,
263 * the {@code Method} object for the method in the foremost interface
264 * that contains the method (either directly or inherited through a
265 * superinterface) in the proxy class's list of interfaces is passed to
266 * the invocation handler's {@code invoke} method, regardless of the
267 * reference type through which the method invocation occurred.
268 *
269 * <p>If a proxy interface contains a method with the same name and
270 * parameter signature as the {@code hashCode}, {@code equals},
271 * or {@code toString} methods of {@code java.lang.Object},
272 * when such a method is invoked on a proxy instance, the
273 * {@code Method} object passed to the invocation handler will have
274 * {@code java.lang.Object} as its declaring class. In other words,
275 * the public, non-final methods of {@code java.lang.Object}
276 * logically precede all of the proxy interfaces for the determination of
277 * which {@code Method} object to pass to the invocation handler.
278 *
279 * <p>Note also that when a duplicate method is dispatched to an
280 * invocation handler, the {@code invoke} method may only throw
281 * checked exception types that are assignable to one of the exception
282 * types in the {@code throws} clause of the method in <i>all</i> of
283 * the proxy interfaces that it can be invoked through. If the
284 * {@code invoke} method throws a checked exception that is not
285 * assignable to any of the exception types declared by the method in one
286 * of the proxy interfaces that it can be invoked through, then an
287 * unchecked {@code UndeclaredThrowableException} will be thrown by
288 * the invocation on the proxy instance. This restriction means that not
289 * all of the exception types returned by invoking
290 * {@code getExceptionTypes} on the {@code Method} object
291 * passed to the {@code invoke} method can necessarily be thrown
292 * successfully by the {@code invoke} method.
293 *
294 * @author Peter Jones
295 * @see InvocationHandler
296 * @since 1.3
297 */
298 public class Proxy implements java.io.Serializable {
299 @java.io.Serial
300 private static final long serialVersionUID = -2222568056686623797L;
301
302 /** parameter types of a proxy class constructor */
303 private static final Class<?>[] constructorParams =
304 { InvocationHandler.class };
305
306 /**
307 * a cache of proxy constructors with
308 * {@link Constructor#setAccessible(boolean) accessible} flag already set
309 */
310 private static final ClassLoaderValue<Constructor<?>> proxyCache =
311 new ClassLoaderValue<>();
312
313 /**
314 * the invocation handler for this proxy instance.
315 * @serial
316 */
317 @SuppressWarnings("serial") // Not statically typed as Serializable
318 protected InvocationHandler h;
319
320 /**
321 * Prohibits instantiation.
322 */
323 private Proxy() {
324 }
325
326 /**
327 * Constructs a new {@code Proxy} instance from a subclass
328 * (typically, a dynamic proxy class) with the specified value
329 * for its invocation handler.
330 *
331 * @param h the invocation handler for this proxy instance
332 *
333 * @throws NullPointerException if the given invocation handler, {@code h},
334 * is {@code null}.
335 */
336 protected Proxy(InvocationHandler h) {
337 Objects.requireNonNull(h);
338 this.h = h;
339 }
340
341 /**
342 * Returns the {@code java.lang.Class} object for a proxy class
343 * given a class loader and an array of interfaces. The proxy class
344 * will be defined by the specified class loader and will implement
345 * all of the supplied interfaces. If any of the given interfaces
346 * is non-public, the proxy class will be non-public. If a proxy class
347 * for the same permutation of interfaces has already been defined by the
348 * class loader, then the existing proxy class will be returned; otherwise,
349 * a proxy class for those interfaces will be generated dynamically
350 * and defined by the class loader.
351 *
352 * @param loader the class loader to define the proxy class
353 * @param interfaces the list of interfaces for the proxy class
354 * to implement
355 * @return a proxy class that is defined in the specified class loader
356 * and that implements the specified interfaces
357 * @throws IllegalArgumentException if any of the <a href="#restrictions">
358 * restrictions</a> on the parameters are violated
359 * @throws SecurityException if a security manager, <em>s</em>, is present
360 * and any of the following conditions is met:
361 * <ul>
362 * <li> the given {@code loader} is {@code null} and
363 * the caller's class loader is not {@code null} and the
364 * invocation of {@link SecurityManager#checkPermission
365 * s.checkPermission} with
366 * {@code RuntimePermission("getClassLoader")} permission
367 * denies access.</li>
368 * <li> for each proxy interface, {@code intf},
369 * the caller's class loader is not the same as or an
370 * ancestor of the class loader for {@code intf} and
371 * invocation of {@link SecurityManager#checkPackageAccess
372 * s.checkPackageAccess()} denies access to {@code intf}.</li>
373 * </ul>
374 * @throws NullPointerException if the {@code interfaces} array
375 * argument or any of its elements are {@code null}
376 *
377 * @deprecated Proxy classes generated in a named module are encapsulated
378 * and not accessible to code outside its module.
379 * {@link Constructor#newInstance(Object...) Constructor.newInstance}
380 * will throw {@code IllegalAccessException} when it is called on
381 * an inaccessible proxy class.
382 * Use {@link #newProxyInstance(ClassLoader, Class[], InvocationHandler)}
383 * to create a proxy instance instead.
384 *
385 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
386 */
387 @Deprecated
388 @CallerSensitive
389 public static Class<?> getProxyClass(ClassLoader loader,
390 Class<?>... interfaces)
391 throws IllegalArgumentException
392 {
393 @SuppressWarnings("removal")
394 Class<?> caller = System.getSecurityManager() == null
395 ? null
396 : Reflection.getCallerClass();
397
398 return getProxyConstructor(caller, loader, interfaces)
399 .getDeclaringClass();
400 }
401
402 /**
403 * Returns the {@code Constructor} object of a proxy class that takes a
404 * single argument of type {@link InvocationHandler}, given a class loader
405 * and an array of interfaces. The returned constructor will have the
406 * {@link Constructor#setAccessible(boolean) accessible} flag already set.
407 *
408 * @param caller passed from a public-facing @CallerSensitive method if
409 * SecurityManager is set or {@code null} if there's no
410 * SecurityManager
411 * @param loader the class loader to define the proxy class
412 * @param interfaces the list of interfaces for the proxy class
413 * to implement
414 * @return a Constructor of the proxy class taking single
415 * {@code InvocationHandler} parameter
416 */
417 private static Constructor<?> getProxyConstructor(Class<?> caller,
418 ClassLoader loader,
419 Class<?>... interfaces)
420 {
421 // optimization for single interface
422 if (interfaces.length == 1) {
423 Class<?> intf = interfaces[0];
424 if (caller != null) {
425 checkProxyAccess(caller, loader, intf);
426 }
427 return proxyCache.sub(intf).computeIfAbsent(
428 loader,
429 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
430 );
431 } else {
432 // interfaces cloned
433 final Class<?>[] intfsArray = interfaces.clone();
434 if (caller != null) {
435 checkProxyAccess(caller, loader, intfsArray);
436 }
437 final List<Class<?>> intfs = Arrays.asList(intfsArray);
438 return proxyCache.sub(intfs).computeIfAbsent(
439 loader,
440 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
441 );
442 }
443 }
444
445 /**
446 * Called from VM native code during dump time.
447 */
448 private static void initCacheForCDS(ClassLoader platformLoader, ClassLoader appLoader) {
449 ProxyBuilder.initCacheForCDS(platformLoader, appLoader);
450 }
451
452 /*
453 * Check permissions required to create a Proxy class.
454 *
455 * To define a proxy class, it performs the access checks as in
456 * Class.forName (VM will invoke ClassLoader.checkPackageAccess):
457 * 1. "getClassLoader" permission check if loader == null
458 * 2. checkPackageAccess on the interfaces it implements
459 *
460 * To get a constructor and new instance of a proxy class, it performs
461 * the package access check on the interfaces it implements
462 * as in Class.getConstructor.
463 *
464 * If an interface is non-public, the proxy class must be defined by
465 * the defining loader of the interface. If the caller's class loader
466 * is not the same as the defining loader of the interface, the VM
467 * will throw IllegalAccessError when the generated proxy class is
468 * being defined.
469 */
470 private static void checkProxyAccess(Class<?> caller,
471 ClassLoader loader,
472 Class<?> ... interfaces)
473 {
474 @SuppressWarnings("removal")
475 SecurityManager sm = System.getSecurityManager();
476 if (sm != null) {
477 ClassLoader ccl = caller.getClassLoader();
478 if (loader == null && ccl != null) {
479 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
480 }
481 ReflectUtil.checkProxyPackageAccess(ccl, interfaces);
482 }
483 }
484
485 /**
486 * Builder for a proxy class.
487 *
488 * If the module is not specified in this ProxyBuilder constructor,
489 * it will map from the given loader and interfaces to the module
490 * in which the proxy class will be defined.
491 */
492 private static final class ProxyBuilder {
493 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
494
495 private static String makeProxyClassNamePrefix() {
496 // Allow unique proxy names to be used across CDS dump time and app run time.
497 if (CDS.isDumpingArchive()) {
498 if (CDS.isUsingArchive()) {
499 return "$Proxy0100"; // CDS dynamic dump
500 } else {
501 return "$Proxy0010"; // CDS static dump
502 }
503 } else {
504 return "$Proxy";
505 }
506 }
507
508 // prefix for all proxy class names
509 private static final String proxyClassNamePrefix = makeProxyClassNamePrefix();
510
511 // next number to use for generation of unique proxy class names
512 private static final AtomicLong nextUniqueNumber = new AtomicLong();
513
514 // a reverse cache of defined proxy classes
515 private static final ClassLoaderValue<Boolean> reverseProxyCache =
516 new ClassLoaderValue<>();
517
518 private record ProxyClassContext(Module module, String packageName, int accessFlags, boolean isDynamicModule) {
519 private ProxyClassContext {
520 if (module.isNamed()) {
521 if (packageName.isEmpty()) {
522 // Per JLS 7.4.2, unnamed package can only exist in unnamed modules.
523 // This means a package-private superinterface exist in the unnamed
524 // package of a named module.
525 throw new InternalError("Unnamed package cannot be added to " + module);
526 }
527
528 if (!module.getDescriptor().packages().contains(packageName)) {
529 throw new InternalError(packageName + " not exist in " + module.getName());
530 }
531
532 if (!module.isOpen(packageName, Proxy.class.getModule())) {
533 // Required for default method invocation
534 throw new InternalError(packageName + " not open to " + Proxy.class.getModule());
535 }
536 } else {
537 if (Modifier.isPublic(accessFlags)) {
538 // All proxy superinterfaces are public, must be in named dynamic module
539 throw new InternalError("public proxy in unnamed module: " + module);
540 }
541 }
542
543 if ((accessFlags & ~Modifier.PUBLIC) != 0) {
544 throw new InternalError("proxy access flags must be Modifier.PUBLIC or 0");
545 }
546 }
547 }
548
549 private static Class<?> defineProxyClass(ProxyClassContext context, List<Class<?>> interfaces) {
550 /*
551 * Choose a name for the proxy class to generate.
552 */
553 String packagePrefix = context.packageName().isEmpty()
554 ? proxyClassNamePrefix
555 : context.packageName() + "." + proxyClassNamePrefix;
556 ClassLoader loader = getLoader(context.module());
557 int accessFlags = context.accessFlags() | Modifier.FINAL;
558
559 if (archivedData != null) {
560 Class<?> pc = archivedData.getArchivedProxyClass(loader, packagePrefix, interfaces);
561 if (pc != null) {
562 reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
563 return pc;
564 }
565 }
566
567 long num = nextUniqueNumber.getAndIncrement();
568 String proxyName = packagePrefix + num;
569
570 trace(proxyName, context.module(), loader, interfaces);
571
572 if (CDS.isLoggingDynamicProxies() && context.isDynamicModule()) {
573 CDS.logDynamicProxy(loader, proxyName, interfaces.toArray(new Class<?>[0]), accessFlags);
574 }
575
576 /*
577 * Generate the specified proxy class.
578 */
579 byte[] proxyClassFile = ProxyGenerator.generateProxyClass(loader, proxyName, interfaces, accessFlags);
580 try {
581 Class<?> pc = JLA.defineClass(loader, proxyName, proxyClassFile,
582 null, "__dynamic_proxy__");
583 reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
584 return pc;
585 } catch (ClassFormatError e) {
586 /*
587 * A ClassFormatError here means that (barring bugs in the
588 * proxy class generation code) there was some other
589 * invalid aspect of the arguments supplied to the proxy
590 * class creation (such as virtual machine limitations
591 * exceeded).
592 */
593 throw new IllegalArgumentException(e.toString());
594 }
595 }
596
597 /**
598 * Called from VM native code to define a proxy class to be stored in archivedData.
599 */
600 private static Class<?> defineProxyClassForCDS(ClassLoader loader, String proxyName, Class<?>[] interfaces,
601 int accessFlags) {
602 ArrayList<Class<?>> list = new ArrayList<>();
603 for (Object o : interfaces) {
604 list.add((Class<?>)o);
605 }
606
607 ProxyBuilder builder = new ProxyBuilder(loader, list);
608 Constructor<?> cons = builder.build();
609 Class<?> proxyClass = cons.getDeclaringClass();
610 archivedData.putArchivedProxyClass(loader, proxyName, list, proxyClass);
611 return proxyClass;
612 }
613
614 /**
615 * Test if given class is a class defined by
616 * {@link #defineProxyClass(ProxyClassContext, List)}
617 */
618 static boolean isProxyClass(Class<?> c) {
619 return Objects.equals(reverseProxyCache.sub(c).get(c.getClassLoader()),
620 Boolean.TRUE);
621 }
622
623 private static boolean isExportedType(Class<?> c) {
624 String pn = c.getPackageName();
625 return Modifier.isPublic(c.getModifiers()) && c.getModule().isExported(pn);
626 }
627
628 private static boolean isPackagePrivateType(Class<?> c) {
629 return !Modifier.isPublic(c.getModifiers());
630 }
631
632 private static String toDetails(Class<?> c) {
633 String access = "unknown";
634 if (isExportedType(c)) {
635 access = "exported";
636 } else if (isPackagePrivateType(c)) {
637 access = "package-private";
638 } else {
639 access = "module-private";
640 }
641 ClassLoader ld = c.getClassLoader();
642 return String.format(" %s/%s %s loader %s",
643 c.getModule().getName(), c.getName(), access, ld);
644 }
645
646 static void trace(String cn,
647 Module module,
648 ClassLoader loader,
649 List<Class<?>> interfaces) {
650 if (isDebug()) {
651 System.err.format("PROXY: %s/%s defined by %s%n",
652 module.getName(), cn, loader);
653 }
654 if (isDebug("debug")) {
655 interfaces.forEach(c -> System.out.println(toDetails(c)));
656 }
657 }
658
659 private static final String DEBUG =
660 GetPropertyAction.privilegedGetProperty("jdk.proxy.debug", "");
661
662 private static boolean isDebug() {
663 return !DEBUG.isEmpty();
664 }
665 private static boolean isDebug(String flag) {
666 return DEBUG.equals(flag);
667 }
668
669 // ProxyBuilder instance members start here....
670
671 private final List<Class<?>> interfaces;
672 private final ProxyClassContext context;
673 ProxyBuilder(ClassLoader loader, List<Class<?>> interfaces) {
674 Objects.requireNonNull(interfaces);
675 if (!VM.isModuleSystemInited()) {
676 throw new InternalError("Proxy is not supported until "
677 + "module system is fully initialized");
678 }
679 if (interfaces.size() > 65535) {
680 throw new IllegalArgumentException("interface limit exceeded: "
681 + interfaces.size());
682 }
683
684 Set<Class<?>> refTypes = referencedTypes(loader, interfaces);
685
686 // IAE if violates any restrictions specified in newProxyInstance
687 validateProxyInterfaces(loader, interfaces, refTypes);
688
689 this.interfaces = interfaces;
690 this.context = proxyClassContext(loader, interfaces, refTypes);
691 assert getLoader(context.module()) == loader;
692 }
693
694 ProxyBuilder(ClassLoader loader, Class<?> intf) {
695 this(loader, Collections.singletonList(intf));
696 }
697
698 /**
699 * Generate a proxy class and return its proxy Constructor with
700 * accessible flag already set. If the target module does not have access
701 * to any interface types, IllegalAccessError will be thrown by the VM
702 * at defineClass time.
703 *
704 * Must call the checkProxyAccess method to perform permission checks
705 * before calling this.
706 */
707 @SuppressWarnings("removal")
708 Constructor<?> build() {
709 Class<?> proxyClass = defineProxyClass(context, interfaces);
710
711 final Constructor<?> cons;
712 try {
713 cons = proxyClass.getConstructor(constructorParams);
714 } catch (NoSuchMethodException e) {
715 throw new InternalError(e.toString(), e);
716 }
717 AccessController.doPrivileged(new PrivilegedAction<Void>() {
718 public Void run() {
719 cons.setAccessible(true);
720 return null;
721 }
722 });
723 return cons;
724 }
725
726 /**
727 * Validate the given proxy interfaces and the given referenced types
728 * are visible to the defining loader.
729 *
730 * @throws IllegalArgumentException if it violates the restrictions
731 * specified in {@link Proxy#newProxyInstance}
732 */
733 private static void validateProxyInterfaces(ClassLoader loader,
734 List<Class<?>> interfaces,
735 Set<Class<?>> refTypes)
736 {
737 Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.size());
738 for (Class<?> intf : interfaces) {
739 /*
740 * Verify that the Class object actually represents an
741 * interface.
742 */
743 if (!intf.isInterface()) {
744 throw new IllegalArgumentException(intf.getName() + " is not an interface");
745 }
746
747 if (intf.isHidden()) {
748 throw new IllegalArgumentException(intf.getName() + " is a hidden interface");
749 }
750
751 if (intf.isSealed()) {
752 throw new IllegalArgumentException(intf.getName() + " is a sealed interface");
753 }
754
755 /*
756 * Verify that the class loader resolves the name of this
757 * interface to the same Class object.
758 */
759 ensureVisible(loader, intf);
760
761 /*
762 * Verify that this interface is not a duplicate.
763 */
764 if (interfaceSet.put(intf, Boolean.TRUE) != null) {
765 throw new IllegalArgumentException("repeated interface: " + intf.getName());
766 }
767 }
768
769 for (Class<?> type : refTypes) {
770 ensureVisible(loader, type);
771 }
772 }
773
774 /*
775 * Returns all types referenced by all public non-static method signatures of
776 * the proxy interfaces
777 */
778 private static Set<Class<?>> referencedTypes(ClassLoader loader,
779 List<Class<?>> interfaces) {
780 var types = new HashSet<Class<?>>();
781 for (var intf : interfaces) {
782 for (Method m : intf.getMethods()) {
783 if (!Modifier.isStatic(m.getModifiers())) {
784 addElementType(types, m.getReturnType());
785 addElementTypes(types, m.getSharedParameterTypes());
786 addElementTypes(types, m.getSharedExceptionTypes());
787 }
788 }
789 }
790 return types;
791 }
792
793 private static void addElementTypes(HashSet<Class<?>> types,
794 Class<?> ... classes) {
795 for (var cls : classes) {
796 addElementType(types, cls);
797 }
798 }
799
800 private static void addElementType(HashSet<Class<?>> types,
801 Class<?> cls) {
802 var type = getElementType(cls);
803 if (!type.isPrimitive()) {
804 types.add(type);
805 }
806 }
807
808 /**
809 * Returns the context for the generated proxy class, including the
810 * module and the package it belongs to and whether it is package-private.
811 *
812 * If any of proxy interface is package-private, then the proxy class
813 * is in the same package and module as the package-private interface.
814 *
815 * If all proxy interfaces are public and in exported packages,
816 * then the proxy class is in a dynamic module in an unconditionally
817 * exported package.
818 *
819 * If all proxy interfaces are public and at least one in a non-exported
820 * package, then the proxy class is in a dynamic module in a
821 * non-exported package.
822 *
823 * The package of proxy class is open to java.base for deep reflective access.
824 *
825 * Reads edge and qualified exports are added for dynamic module to access.
826 */
827 private static ProxyClassContext proxyClassContext(ClassLoader loader,
828 List<Class<?>> interfaces,
829 Set<Class<?>> refTypes) {
830 Map<Class<?>, Module> packagePrivateTypes = new HashMap<>();
831 boolean nonExported = false;
832
833 for (Class<?> intf : interfaces) {
834 Module m = intf.getModule();
835 if (!Modifier.isPublic(intf.getModifiers())) {
836 packagePrivateTypes.put(intf, m);
837 } else {
838 if (!intf.getModule().isExported(intf.getPackageName())) {
839 // module-private types
840 nonExported = true;
841 }
842 }
843 }
844
845 if (packagePrivateTypes.size() > 0) {
846 // all package-private types must be in the same runtime package
847 // i.e. same package name and same module (named or unnamed)
848 //
849 // Configuration will fail if M1 and in M2 defined by the same loader
850 // and both have the same package p (so no need to check class loader)
851 Module targetModule = null;
852 String targetPackageName = null;
853 for (Map.Entry<Class<?>, Module> e : packagePrivateTypes.entrySet()) {
854 Class<?> intf = e.getKey();
855 Module m = e.getValue();
856 if ((targetModule != null && targetModule != m) ||
857 (targetPackageName != null && targetPackageName != intf.getPackageName())) {
858 throw new IllegalArgumentException(
859 "cannot have non-public interfaces in different packages");
860 }
861 if (getLoader(m) != loader) {
862 // the specified loader is not the same class loader
863 // of the non-public interface
864 throw new IllegalArgumentException(
865 "non-public interface is not defined by the given loader");
866 }
867
868 targetModule = m;
869 targetPackageName = e.getKey().getPackageName();
870 }
871
872 // validate if the target module can access all other interfaces
873 for (Class<?> intf : interfaces) {
874 Module m = intf.getModule();
875 if (m == targetModule) continue;
876
877 if (!targetModule.canRead(m) || !m.isExported(intf.getPackageName(), targetModule)) {
878 throw new IllegalArgumentException(targetModule + " can't access " + intf.getName());
879 }
880 }
881
882 // opens the package of the non-public proxy class for java.base to access
883 if (targetModule.isNamed()) {
884 Modules.addOpens(targetModule, targetPackageName, Proxy.class.getModule());
885 }
886 // return the module of the package-private interface
887 return new ProxyClassContext(targetModule, targetPackageName, 0, false);
888 }
889
890 // All proxy interfaces are public. So maps to a dynamic proxy module
891 // and add reads edge and qualified exports, if necessary
892 Module targetModule = getDynamicModule(loader);
893
894 // set up proxy class access to proxy interfaces and types
895 // referenced in the method signature
896 Set<Class<?>> types = new HashSet<>(interfaces);
897 types.addAll(refTypes);
898 for (Class<?> c : types) {
899 ensureAccess(targetModule, c);
900 }
901
902 var pkgName = nonExported ? PROXY_PACKAGE_PREFIX + '.' + targetModule.getName()
903 : targetModule.getName();
904 return new ProxyClassContext(targetModule, pkgName, Modifier.PUBLIC, true);
905 }
906
907 /*
908 * Ensure the given module can access the given class.
909 */
910 private static void ensureAccess(Module target, Class<?> c) {
911 Module m = c.getModule();
912 if (target == m) return;
913
914 // add read edge and qualified export for the target module to access
915 if (!target.canRead(m)) {
916 Modules.addReads(target, m);
917 }
918 String pn = c.getPackageName();
919 if (!m.isExported(pn, target)) {
920 Modules.addExports(m, pn, target);
921 }
922 }
923
924 /*
925 * Ensure the given class is visible to the class loader.
926 */
927 private static void ensureVisible(ClassLoader ld, Class<?> c) {
928 Class<?> type = null;
929 try {
930 type = Class.forName(c.getName(), false, ld);
931 } catch (ClassNotFoundException e) {
932 }
933 if (type != c) {
934 throw new IllegalArgumentException(c.getName() +
935 " referenced from a method is not visible from class loader: " + JLA.getLoaderNameID(ld));
936 }
937 }
938
939 private static Class<?> getElementType(Class<?> type) {
940 Class<?> e = type;
941 while (e.isArray()) {
942 e = e.getComponentType();
943 }
944 return e;
945 }
946
947 private static final ClassLoaderValue<Module> dynProxyModules =
948 new ClassLoaderValue<>();
949 private static final AtomicInteger counter = new AtomicInteger();
950
951 /*
952 * Define a dynamic module with a package named $MODULE which
953 * is unconditionally exported and another package named
954 * com.sun.proxy.$MODULE which is encapsulated.
955 *
956 * Each class loader will have one dynamic module.
957 */
958 private static Module getDynamicModule(ClassLoader loader) {
959 return dynProxyModules.computeIfAbsent(loader, (ld, clv) -> {
960 // create a dynamic module and setup module access
961 int num = counter.incrementAndGet();
962 String mn = "jdk.proxy" + num;
963 String pn = PROXY_PACKAGE_PREFIX + "." + mn;
964 ModuleDescriptor descriptor =
965 ModuleDescriptor.newModule(mn, Set.of(SYNTHETIC))
966 .packages(Set.of(pn, mn))
967 .exports(mn)
968 .build();
969 Module m = Modules.defineModule(ld, descriptor, null);
970 openDynamicModule(m);
971
972 if (CDS.isDumpingHeap() && archivedData != null) {
973 archivedData.recordModule(loader, m, num);
974 }
975 return m;
976 });
977 }
978
979 private static void openDynamicModule(Module m) {
980 String mn = m.getName();
981 String pn = PROXY_PACKAGE_PREFIX + "." + mn;
982 Modules.addReads(m, Proxy.class.getModule());
983 Modules.addExports(m, mn);
984 // java.base to create proxy instance and access its Lookup instance
985 Modules.addOpens(m, pn, Proxy.class.getModule());
986 Modules.addOpens(m, mn, Proxy.class.getModule());
987 }
988
989 static class ArchivedData {
990 static class InterfacesKey {
991 Class<?>[] intfsArray;
992 InterfacesKey(List<Class<?>> intfs) {
993 intfsArray = new Class<?>[intfs.size()];
994 for (int i = 0; i < intfs.size(); i++) {
995 intfsArray[i] = intfs.get(i);
996 }
997 }
998 @Override
999 public int hashCode() {
1000 return Arrays.hashCode(intfsArray);
1001 }
1002 @Override
1003 public boolean equals(Object other) {
1004 if (other instanceof InterfacesKey) {
1005 InterfacesKey o = (InterfacesKey)other;
1006 int len = intfsArray.length;
1007 if (len != o.intfsArray.length) {
1008 return false;
1009 }
1010 Class<?>[] oa = o.intfsArray;
1011 for (int i = 0; i < len; i++) {
1012 if (intfsArray[i] != oa[i]) {
1013 return false;
1014 }
1015 }
1016 return true;
1017 } else {
1018 return false;
1019 }
1020 }
1021 }
1022
1023 ClassLoader platformLoader;
1024 ClassLoader appLoader;
1025 HashMap<InterfacesKey,Class<?>> bootCache = new HashMap<>();
1026 HashMap<InterfacesKey,Class<?>> platformCache = new HashMap<>();
1027 HashMap<InterfacesKey,Class<?>> appCache = new HashMap<>();
1028
1029 Module bootModule;
1030 Module platformModule;
1031 Module appModule;
1032 int maxNum;
1033
1034 ArchivedData(ClassLoader plat, ClassLoader app) {
1035 platformLoader = plat;
1036 appLoader = app;
1037 }
1038
1039 HashMap<InterfacesKey,Class<?>> cacheForLoader(ClassLoader loader) {
1040 if (loader == null) {
1041 return bootCache;
1042 } else if (loader == platformLoader) {
1043 return platformCache;
1044 } else if (loader == appLoader) {
1045 return appCache;
1046 } else {
1047 return null;
1048 }
1049 }
1050
1051 void recordModule(ClassLoader loader, Module m, int num) {
1052 if (loader == null) {
1053 bootModule = m;
1054 } else if (loader == platformLoader) {
1055 platformModule = m;
1056 } else if (loader == appLoader) {
1057 appModule = m;
1058 } else {
1059 throw new UnsupportedOperationException("Class loader " + loader + " is not supported");
1060 }
1061 if (maxNum < num) {
1062 maxNum = num;
1063 }
1064 }
1065
1066 void restore() {
1067 // The info for addReads/addExports/addOpens are maintained solely inside the VM.
1068 // CDS currently doesn't properly archive such info for the dynamically generated modules,
1069 // so we have to recreate them at runtime.
1070 //
1071 // TODO -- consider improving CDS to archive the above info, so we can avoid calling openDynamicModule()
1072 if (bootModule != null) {
1073 Module last = dynProxyModules.putIfAbsent(null, bootModule);
1074 assert last == null;
1075 openDynamicModule(bootModule);
1076 }
1077 if (platformModule != null) {
1078 Module last = dynProxyModules.putIfAbsent(platformLoader, platformModule);
1079 assert last == null;
1080 openDynamicModule(platformModule);
1081 }
1082 if (appModule != null) {
1083 Module last = dynProxyModules.putIfAbsent(appLoader, appModule);
1084 assert last == null;
1085 openDynamicModule(appModule);
1086 }
1087
1088 while (maxNum > counter.get()) {
1089 counter.incrementAndGet();
1090 }
1091 }
1092
1093
1094 Class<?> getArchivedProxyClass(ClassLoader loader, String proxyPrefix, List<Class<?>> interfaces) {
1095 HashMap<InterfacesKey,Class<?>> cache = cacheForLoader(loader);
1096 if (cache != null && cache.size() > 0) {
1097 InterfacesKey key = new InterfacesKey(interfaces);
1098 return cache.get(key);
1099 } else {
1100 return null;
1101 }
1102 }
1103
1104 void putArchivedProxyClass(ClassLoader loader, String proxyName, List<Class<?>> interfaces, Class<?> cls) {
1105 HashMap<InterfacesKey,Class<?>> cache = cacheForLoader(loader);
1106 if (cache != null) {
1107 InterfacesKey key = new InterfacesKey(interfaces);
1108 cache.put(key, cls);
1109 }
1110 }
1111 }
1112
1113 static ArchivedData archivedData;
1114
1115 static {
1116 CDS.initializeFromArchive(ProxyBuilder.class);
1117 if (archivedData != null) {
1118 archivedData.restore();
1119 }
1120 }
1121
1122 private static void initCacheForCDS(ClassLoader platformLoader, ClassLoader appLoader) {
1123 archivedData = new ArchivedData(platformLoader, appLoader);
1124 }
1125 }
1126
1127 /**
1128 * Returns a proxy instance for the specified interfaces
1129 * that dispatches method invocations to the specified invocation
1130 * handler.
1131 * <p>
1132 * <a id="restrictions">{@code IllegalArgumentException} will be thrown
1133 * if any of the following restrictions is violated:</a>
1134 * <ul>
1135 * <li>All of {@code Class} objects in the given {@code interfaces} array
1136 * must represent {@linkplain Class#isHidden() non-hidden} and
1137 * {@linkplain Class#isSealed() non-sealed} interfaces,
1138 * not classes or primitive types.
1139 *
1140 * <li>No two elements in the {@code interfaces} array may
1141 * refer to identical {@code Class} objects.
1142 *
1143 * <li>All of the interface types must be visible by name through the
1144 * specified class loader. In other words, for class loader
1145 * {@code cl} and every interface {@code i}, the following
1146 * expression must be true:<p>
1147 * {@code Class.forName(i.getName(), false, cl) == i}
1148 *
1149 * <li>All of the types referenced by all
1150 * public method signatures of the specified interfaces
1151 * and those inherited by their superinterfaces
1152 * must be visible by name through the specified class loader.
1153 *
1154 * <li>All non-public interfaces must be in the same package
1155 * and module, defined by the specified class loader and
1156 * the module of the non-public interfaces can access all of
1157 * the interface types; otherwise, it would not be possible for
1158 * the proxy class to implement all of the interfaces,
1159 * regardless of what package it is defined in.
1160 *
1161 * <li>For any set of member methods of the specified interfaces
1162 * that have the same signature:
1163 * <ul>
1164 * <li>If the return type of any of the methods is a primitive
1165 * type or void, then all of the methods must have that same
1166 * return type.
1167 * <li>Otherwise, one of the methods must have a return type that
1168 * is assignable to all of the return types of the rest of the
1169 * methods.
1170 * </ul>
1171 *
1172 * <li>The resulting proxy class must not exceed any limits imposed
1173 * on classes by the virtual machine. For example, the VM may limit
1174 * the number of interfaces that a class may implement to 65535; in
1175 * that case, the size of the {@code interfaces} array must not
1176 * exceed 65535.
1177 * </ul>
1178 *
1179 * <p>Note that the order of the specified proxy interfaces is
1180 * significant: two requests for a proxy class with the same combination
1181 * of interfaces but in a different order will result in two distinct
1182 * proxy classes.
1183 *
1184 * @param loader the class loader to define the proxy class
1185 * @param interfaces the list of interfaces for the proxy class
1186 * to implement
1187 * @param h the invocation handler to dispatch method invocations to
1188 * @return a proxy instance with the specified invocation handler of a
1189 * proxy class that is defined by the specified class loader
1190 * and that implements the specified interfaces
1191 * @throws IllegalArgumentException if any of the <a href="#restrictions">
1192 * restrictions</a> on the parameters are violated
1193 * @throws SecurityException if a security manager, <em>s</em>, is present
1194 * and any of the following conditions is met:
1195 * <ul>
1196 * <li> the given {@code loader} is {@code null} and
1197 * the caller's class loader is not {@code null} and the
1198 * invocation of {@link SecurityManager#checkPermission
1199 * s.checkPermission} with
1200 * {@code RuntimePermission("getClassLoader")} permission
1201 * denies access;</li>
1202 * <li> for each proxy interface, {@code intf},
1203 * the caller's class loader is not the same as or an
1204 * ancestor of the class loader for {@code intf} and
1205 * invocation of {@link SecurityManager#checkPackageAccess
1206 * s.checkPackageAccess()} denies access to {@code intf};</li>
1207 * <li> any of the given proxy interfaces is non-public and the
1208 * caller class is not in the same {@linkplain Package runtime package}
1209 * as the non-public interface and the invocation of
1210 * {@link SecurityManager#checkPermission s.checkPermission} with
1211 * {@code ReflectPermission("newProxyInPackage.{package name}")}
1212 * permission denies access.</li>
1213 * </ul>
1214 * @throws NullPointerException if the {@code interfaces} array
1215 * argument or any of its elements are {@code null}, or
1216 * if the invocation handler, {@code h}, is
1217 * {@code null}
1218 *
1219 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
1220 */
1221 @CallerSensitive
1222 public static Object newProxyInstance(ClassLoader loader,
1223 Class<?>[] interfaces,
1224 InvocationHandler h) {
1225 Objects.requireNonNull(h);
1226
1227 @SuppressWarnings("removal")
1228 final Class<?> caller = System.getSecurityManager() == null
1229 ? null
1230 : Reflection.getCallerClass();
1231
1232 /*
1233 * Look up or generate the designated proxy class and its constructor.
1234 */
1235 Constructor<?> cons = getProxyConstructor(caller, loader, interfaces);
1236
1237 return newProxyInstance(caller, cons, h);
1238 }
1239
1240 private static Object newProxyInstance(Class<?> caller, // null if no SecurityManager
1241 Constructor<?> cons,
1242 InvocationHandler h) {
1243 /*
1244 * Invoke its constructor with the designated invocation handler.
1245 */
1246 try {
1247 if (caller != null) {
1248 checkNewProxyPermission(caller, cons.getDeclaringClass());
1249 }
1250
1251 return cons.newInstance(new Object[]{h});
1252 } catch (IllegalAccessException | InstantiationException e) {
1253 throw new InternalError(e.toString(), e);
1254 } catch (InvocationTargetException e) {
1255 Throwable t = e.getCause();
1256 if (t instanceof RuntimeException re) {
1257 throw re;
1258 } else {
1259 throw new InternalError(t.toString(), t);
1260 }
1261 }
1262 }
1263
1264 private static void checkNewProxyPermission(Class<?> caller, Class<?> proxyClass) {
1265 @SuppressWarnings("removal")
1266 SecurityManager sm = System.getSecurityManager();
1267 if (sm != null) {
1268 if (ReflectUtil.isNonPublicProxyClass(proxyClass)) {
1269 ClassLoader ccl = caller.getClassLoader();
1270 ClassLoader pcl = proxyClass.getClassLoader();
1271
1272 // do permission check if the caller is in a different runtime package
1273 // of the proxy class
1274 String pkg = proxyClass.getPackageName();
1275 String callerPkg = caller.getPackageName();
1276
1277 if (pcl != ccl || !pkg.equals(callerPkg)) {
1278 sm.checkPermission(new ReflectPermission("newProxyInPackage." + pkg));
1279 }
1280 }
1281 }
1282 }
1283
1284 /**
1285 * Returns the class loader for the given module.
1286 */
1287 @SuppressWarnings("removal")
1288 private static ClassLoader getLoader(Module m) {
1289 PrivilegedAction<ClassLoader> pa = m::getClassLoader;
1290 return AccessController.doPrivileged(pa);
1291 }
1292
1293 /**
1294 * Returns true if the given class is a proxy class.
1295 *
1296 * @implNote The reliability of this method is important for the ability
1297 * to use it to make security decisions, so its implementation should
1298 * not just test if the class in question extends {@code Proxy}.
1299 *
1300 * @param cl the class to test
1301 * @return {@code true} if the class is a proxy class and
1302 * {@code false} otherwise
1303 * @throws NullPointerException if {@code cl} is {@code null}
1304 */
1305 public static boolean isProxyClass(Class<?> cl) {
1306 return Proxy.class.isAssignableFrom(cl) && ProxyBuilder.isProxyClass(cl);
1307 }
1308
1309 /**
1310 * Returns the invocation handler for the specified proxy instance.
1311 *
1312 * @param proxy the proxy instance to return the invocation handler for
1313 * @return the invocation handler for the proxy instance
1314 * @throws IllegalArgumentException if the argument is not a
1315 * proxy instance
1316 * @throws SecurityException if a security manager, <em>s</em>, is present
1317 * and the caller's class loader is not the same as or an
1318 * ancestor of the class loader for the invocation handler
1319 * and invocation of {@link SecurityManager#checkPackageAccess
1320 * s.checkPackageAccess()} denies access to the invocation
1321 * handler's class.
1322 */
1323 @SuppressWarnings("removal")
1324 @CallerSensitive
1325 public static InvocationHandler getInvocationHandler(Object proxy)
1326 throws IllegalArgumentException
1327 {
1328 /*
1329 * Verify that the object is actually a proxy instance.
1330 */
1331 if (!isProxyClass(proxy.getClass())) {
1332 throw new IllegalArgumentException("not a proxy instance");
1333 }
1334
1335 final Proxy p = (Proxy) proxy;
1336 final InvocationHandler ih = p.h;
1337 if (System.getSecurityManager() != null) {
1338 Class<?> ihClass = ih.getClass();
1339 Class<?> caller = Reflection.getCallerClass();
1340 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(),
1341 ihClass.getClassLoader()))
1342 {
1343 ReflectUtil.checkPackageAccess(ihClass);
1344 }
1345 }
1346
1347 return ih;
1348 }
1349
1350 private static final String PROXY_PACKAGE_PREFIX = ReflectUtil.PROXY_PACKAGE;
1351
1352 /**
1353 * A cache of Method -> MethodHandle for default methods.
1354 */
1355 private static final ClassValue<ConcurrentHashMap<Method, MethodHandle>>
1356 DEFAULT_METHODS_MAP = new ClassValue<>() {
1357 @Override
1358 protected ConcurrentHashMap<Method, MethodHandle> computeValue(Class<?> type) {
1359 return new ConcurrentHashMap<>(4);
1360 }
1361 };
1362
1363 private static ConcurrentHashMap<Method, MethodHandle> defaultMethodMap(Class<?> proxyClass) {
1364 assert isProxyClass(proxyClass);
1365 return DEFAULT_METHODS_MAP.get(proxyClass);
1366 }
1367
1368 static final Object[] EMPTY_ARGS = new Object[0];
1369
1370 static MethodHandle defaultMethodHandle(Class<? extends Proxy> proxyClass, Method method) {
1371 // lookup the cached method handle
1372 ConcurrentHashMap<Method, MethodHandle> methods = defaultMethodMap(proxyClass);
1373 MethodHandle superMH = methods.get(method);
1374 if (superMH == null) {
1375 MethodType type = methodType(method.getReturnType(), method.getParameterTypes());
1376 MethodHandles.Lookup lookup = MethodHandles.lookup();
1377 Class<?> proxyInterface = findProxyInterfaceOrElseThrow(proxyClass, method);
1378 MethodHandle dmh;
1379 try {
1380 dmh = proxyClassLookup(lookup, proxyClass)
1381 .findSpecial(proxyInterface, method.getName(), type, proxyClass)
1382 .withVarargs(false);
1383 } catch (IllegalAccessException | NoSuchMethodException e) {
1384 // should not reach here
1385 throw new InternalError(e);
1386 }
1387 // this check can be turned into assertion as it is guaranteed to succeed by the virtue of
1388 // looking up a default (instance) method declared or inherited by proxyInterface
1389 // while proxyClass implements (is a subtype of) proxyInterface ...
1390 assert ((BooleanSupplier) () -> {
1391 try {
1392 // make sure that the method type matches
1393 dmh.asType(type.insertParameterTypes(0, proxyClass));
1394 return true;
1395 } catch (WrongMethodTypeException e) {
1396 return false;
1397 }
1398 }).getAsBoolean() : "Wrong method type";
1399 // change return type to Object
1400 MethodHandle mh = dmh.asType(dmh.type().changeReturnType(Object.class));
1401 // wrap any exception thrown with InvocationTargetException
1402 mh = MethodHandles.catchException(mh, Throwable.class, InvocationException.wrapMH());
1403 // spread array of arguments among parameters (skipping 1st parameter - target)
1404 mh = mh.asSpreader(1, Object[].class, type.parameterCount());
1405 // change target type to Object
1406 mh = mh.asType(MethodType.methodType(Object.class, Object.class, Object[].class));
1407
1408 // push MH into cache
1409 MethodHandle cached = methods.putIfAbsent(method, mh);
1410 if (cached != null) {
1411 superMH = cached;
1412 } else {
1413 superMH = mh;
1414 }
1415 }
1416 return superMH;
1417 }
1418
1419 /**
1420 * Finds the first proxy interface that declares the given method
1421 * directly or indirectly.
1422 *
1423 * @throws IllegalArgumentException if not found
1424 */
1425 private static Class<?> findProxyInterfaceOrElseThrow(Class<?> proxyClass, Method method) {
1426 Class<?> declaringClass = method.getDeclaringClass();
1427 if (!declaringClass.isInterface()) {
1428 throw new IllegalArgumentException("\"" + method +
1429 "\" is not a method declared in the proxy class");
1430 }
1431
1432 List<Class<?>> proxyInterfaces = Arrays.asList(proxyClass.getInterfaces());
1433 // the method's declaring class is a proxy interface
1434 if (proxyInterfaces.contains(declaringClass))
1435 return declaringClass;
1436
1437 // find the first proxy interface that inherits the default method
1438 // i.e. the declaring class of the default method is a superinterface
1439 // of the proxy interface
1440 Deque<Class<?>> deque = new ArrayDeque<>();
1441 Set<Class<?>> visited = new HashSet<>();
1442 boolean indirectMethodRef = false;
1443 for (Class<?> proxyIntf : proxyInterfaces) {
1444 assert proxyIntf != declaringClass;
1445 visited.add(proxyIntf);
1446 deque.add(proxyIntf);
1447
1448 // for each proxy interface, traverse its subinterfaces with
1449 // breadth-first search to find a subinterface declaring the
1450 // default method
1451 Class<?> c;
1452 while ((c = deque.poll()) != null) {
1453 if (c == declaringClass) {
1454 try {
1455 // check if this method is the resolved method if referenced from
1456 // this proxy interface (i.e. this method is not implemented
1457 // by any other superinterface)
1458 Method m = proxyIntf.getMethod(method.getName(), method.getSharedParameterTypes());
1459 if (m.getDeclaringClass() == declaringClass) {
1460 return proxyIntf;
1461 }
1462 indirectMethodRef = true;
1463 } catch (NoSuchMethodException e) {}
1464
1465 // skip traversing its superinterfaces
1466 // another proxy interface may extend it and so
1467 // the method's declaring class is left unvisited.
1468 continue;
1469 }
1470 // visit all superinterfaces of one proxy interface to find if
1471 // this proxy interface inherits the method directly or indirectly
1472 visited.add(c);
1473 for (Class<?> superIntf : c.getInterfaces()) {
1474 if (!visited.contains(superIntf) && !deque.contains(superIntf)) {
1475 if (superIntf == declaringClass) {
1476 // fast-path as the matching subinterface is found
1477 deque.addFirst(superIntf);
1478 } else {
1479 deque.add(superIntf);
1480 }
1481 }
1482 }
1483 }
1484 }
1485
1486 throw new IllegalArgumentException("\"" + method + (indirectMethodRef
1487 ? "\" is overridden directly or indirectly by the proxy interfaces"
1488 : "\" is not a method declared in the proxy class"));
1489 }
1490
1491 /**
1492 * This method invokes the proxy's proxyClassLookup method to get a
1493 * Lookup on the proxy class.
1494 *
1495 * @return a lookup for proxy class of this proxy instance
1496 */
1497 @SuppressWarnings("removal")
1498 private static MethodHandles.Lookup proxyClassLookup(MethodHandles.Lookup caller, Class<?> proxyClass) {
1499 return AccessController.doPrivileged(new PrivilegedAction<>() {
1500 @Override
1501 public MethodHandles.Lookup run() {
1502 try {
1503 Method m = proxyClass.getDeclaredMethod("proxyClassLookup", MethodHandles.Lookup.class);
1504 m.setAccessible(true);
1505 return (MethodHandles.Lookup) m.invoke(null, caller);
1506 } catch (ReflectiveOperationException e) {
1507 throw new InternalError(e);
1508 }
1509 }
1510 });
1511 }
1512
1513 /*
1514 * Invoke the default method of the given proxy with an explicit caller class.
1515 *
1516 * @throws IllegalAccessException if the proxy interface is inaccessible to the caller
1517 * if caller is non-null
1518 */
1519 static Object invokeDefault(Object proxy, Method method, Object[] args, Class<?> caller)
1520 throws Throwable {
1521 // verify that the object is actually a proxy instance
1522 if (!Proxy.isProxyClass(proxy.getClass())) {
1523 throw new IllegalArgumentException("'proxy' is not a proxy instance");
1524 }
1525 if (!method.isDefault()) {
1526 throw new IllegalArgumentException("\"" + method + "\" is not a default method");
1527 }
1528 @SuppressWarnings("unchecked")
1529 Class<? extends Proxy> proxyClass = (Class<? extends Proxy>)proxy.getClass();
1530
1531 // skip access check if caller is null
1532 if (caller != null) {
1533 Class<?> intf = method.getDeclaringClass();
1534 // access check on the default method
1535 method.checkAccess(caller, intf, proxyClass, method.getModifiers());
1536 }
1537
1538 MethodHandle mh = Proxy.defaultMethodHandle(proxyClass, method);
1539 // invoke the super method
1540 try {
1541 // the args array can be null if the number of formal parameters required by
1542 // the method is zero (consistent with Method::invoke)
1543 Object[] params = args != null ? args : Proxy.EMPTY_ARGS;
1544 return mh.invokeExact(proxy, params);
1545 } catch (ClassCastException | NullPointerException e) {
1546 throw new IllegalArgumentException(e.getMessage(), e);
1547 } catch (Proxy.InvocationException e) {
1548 // unwrap and throw the exception thrown by the default method
1549 throw e.getCause();
1550 }
1551 }
1552
1553 /**
1554 * Internal exception type to wrap the exception thrown by the default method
1555 * so that it can distinguish CCE and NPE thrown due to the arguments
1556 * incompatible with the method signature.
1557 */
1558 static class InvocationException extends ReflectiveOperationException {
1559 @java.io.Serial
1560 private static final long serialVersionUID = 0L;
1561
1562 InvocationException(Throwable cause) {
1563 super(cause);
1564 }
1565
1566 /**
1567 * Wraps given cause with InvocationException and throws it.
1568 */
1569 static Object wrap(Throwable cause) throws InvocationException {
1570 throw new InvocationException(cause);
1571 }
1572
1573 @Stable
1574 static MethodHandle wrapMethodHandle;
1575
1576 static MethodHandle wrapMH() {
1577 MethodHandle mh = wrapMethodHandle;
1578 if (mh == null) {
1579 try {
1580 wrapMethodHandle = mh = MethodHandles.lookup().findStatic(
1581 InvocationException.class,
1582 "wrap",
1583 MethodType.methodType(Object.class, Throwable.class)
1584 );
1585 } catch (NoSuchMethodException | IllegalAccessException e) {
1586 throw new InternalError(e);
1587 }
1588 }
1589 return mh;
1590 }
1591 }
1592
1593 }