1 /*
2 * Copyright (c) 2013, 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2019, Azul Systems, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 */
26
27 package java.lang;
28
29 import java.io.InputStream;
30 import java.io.IOException;
31 import java.io.UncheckedIOException;
32 import java.io.File;
33 import java.lang.reflect.Constructor;
34 import java.lang.reflect.InvocationTargetException;
35 import java.net.URL;
36 import java.security.AccessController;
37 import java.security.AccessControlContext;
38 import java.security.CodeSource;
39 import java.security.PrivilegedAction;
40 import java.security.ProtectionDomain;
41 import java.security.cert.Certificate;
42 import java.util.ArrayList;
43 import java.util.Collections;
44 import java.util.Enumeration;
45 import java.util.HashMap;
46 import java.util.Map;
47 import java.util.NoSuchElementException;
48 import java.util.Objects;
49 import java.util.Set;
50 import java.util.Spliterator;
51 import java.util.Spliterators;
52 import java.util.WeakHashMap;
53 import java.util.concurrent.ConcurrentHashMap;
54 import java.util.function.Supplier;
55 import java.util.stream.Stream;
56 import java.util.stream.StreamSupport;
57
58 import jdk.internal.loader.BootLoader;
59 import jdk.internal.loader.BuiltinClassLoader;
60 import jdk.internal.loader.ClassLoaders;
61 import jdk.internal.loader.NativeLibrary;
62 import jdk.internal.loader.NativeLibraries;
63 import jdk.internal.perf.PerfCounter;
64 import jdk.internal.misc.Unsafe;
65 import jdk.internal.misc.VM;
66 import jdk.internal.reflect.CallerSensitive;
67 import jdk.internal.reflect.CallerSensitiveAdapter;
68 import jdk.internal.reflect.Reflection;
69 import jdk.internal.util.StaticProperty;
70 import sun.reflect.misc.ReflectUtil;
71 import sun.security.util.SecurityConstants;
72
73 /**
74 * A class loader is an object that is responsible for loading classes. The
75 * class {@code ClassLoader} is an abstract class. Given the <a
76 * href="#binary-name">binary name</a> of a class, a class loader should attempt to
77 * locate or generate data that constitutes a definition for the class. A
78 * typical strategy is to transform the name into a file name and then read a
79 * "class file" of that name from a file system.
80 *
81 * <p> Every {@link java.lang.Class Class} object contains a {@link
82 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
83 * it.
84 *
85 * <p> {@code Class} objects for array classes are not created by class
86 * loaders, but are created automatically as required by the Java runtime.
87 * The class loader for an array class, as returned by {@link
88 * Class#getClassLoader()} is the same as the class loader for its element
89 * type; if the element type is a primitive type, then the array class has no
90 * class loader.
91 *
92 * <p> Applications implement subclasses of {@code ClassLoader} in order to
93 * extend the manner in which the Java virtual machine dynamically loads
94 * classes.
95 *
96 * <p> Class loaders may typically be used by security managers to indicate
97 * security domains.
98 *
99 * <p> In addition to loading classes, a class loader is also responsible for
100 * locating resources. A resource is some data (a "{@code .class}" file,
101 * configuration data, or an image for example) that is identified with an
102 * abstract '/'-separated path name. Resources are typically packaged with an
103 * application or library so that they can be located by code in the
104 * application or library. In some cases, the resources are included so that
105 * they can be located by other libraries.
106 *
107 * <p> The {@code ClassLoader} class uses a delegation model to search for
108 * classes and resources. Each instance of {@code ClassLoader} has an
109 * associated parent class loader. When requested to find a class or
110 * resource, a {@code ClassLoader} instance will usually delegate the search
111 * for the class or resource to its parent class loader before attempting to
112 * find the class or resource itself.
113 *
114 * <p> Class loaders that support concurrent loading of classes are known as
115 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
116 * loaders and are required to register themselves at their class initialization
117 * time by invoking the {@link
118 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
119 * method. Note that the {@code ClassLoader} class is registered as parallel
120 * capable by default. However, its subclasses still need to register themselves
121 * if they are parallel capable.
122 * In environments in which the delegation model is not strictly
123 * hierarchical, class loaders need to be parallel capable, otherwise class
124 * loading can lead to deadlocks because the loader lock is held for the
125 * duration of the class loading process (see {@link #loadClass
126 * loadClass} methods).
127 *
128 * <h2> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h2>
129 *
130 * The Java run-time has the following built-in class loaders:
131 *
132 * <ul>
133 * <li><p>Bootstrap class loader.
134 * It is the virtual machine's built-in class loader, typically represented
135 * as {@code null}, and does not have a parent.</li>
136 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
137 * The platform class loader is responsible for loading the
138 * <em>platform classes</em>. Platform classes include Java SE platform APIs,
139 * their implementation classes and JDK-specific run-time classes that are
140 * defined by the platform class loader or its ancestors.
141 * The platform class loader can be used as the parent of a {@code ClassLoader}
142 * instance.
143 * <p> To allow for upgrading/overriding of modules defined to the platform
144 * class loader, and where upgraded modules read modules defined to class
145 * loaders other than the platform class loader and its ancestors, then
146 * the platform class loader may have to delegate to other class loaders,
147 * the application class loader for example.
148 * In other words, classes in named modules defined to class loaders
149 * other than the platform class loader and its ancestors may be visible
150 * to the platform class loader. </li>
151 * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
152 * It is also known as <em>application class loader</em> and is distinct
153 * from the platform class loader.
154 * The system class loader is typically used to define classes on the
155 * application class path, module path, and JDK-specific tools.
156 * The platform class loader is the parent or an ancestor of the system class
157 * loader, so the system class loader can load platform classes by delegating
158 * to its parent.</li>
159 * </ul>
160 *
161 * <p> Normally, the Java virtual machine loads classes from the local file
162 * system in a platform-dependent manner.
163 * However, some classes may not originate from a file; they may originate
164 * from other sources, such as the network, or they could be constructed by an
165 * application. The method {@link #defineClass(String, byte[], int, int)
166 * defineClass} converts an array of bytes into an instance of class
167 * {@code Class}. Instances of this newly defined class can be created using
168 * {@link Class#newInstance Class.newInstance}.
169 *
170 * <p> The methods and constructors of objects created by a class loader may
171 * reference other classes. To determine the class(es) referred to, the Java
172 * virtual machine invokes the {@link #loadClass loadClass} method of
173 * the class loader that originally created the class.
174 *
175 * <p> For example, an application could create a network class loader to
176 * download class files from a server. Sample code might look like:
177 *
178 * <blockquote><pre>
179 * ClassLoader loader = new NetworkClassLoader(host, port);
180 * Object main = loader.loadClass("Main", true).newInstance();
181 * . . .
182 * </pre></blockquote>
183 *
184 * <p> The network class loader subclass must define the methods {@link
185 * #findClass findClass} and {@code loadClassData} to load a class
186 * from the network. Once it has downloaded the bytes that make up the class,
187 * it should use the method {@link #defineClass defineClass} to
188 * create a class instance. A sample implementation is:
189 *
190 * <blockquote><pre>
191 * class NetworkClassLoader extends ClassLoader {
192 * String host;
193 * int port;
194 *
195 * public Class findClass(String name) {
196 * byte[] b = loadClassData(name);
197 * return defineClass(name, b, 0, b.length);
198 * }
199 *
200 * private byte[] loadClassData(String name) {
201 * // load the class data from the connection
202 * . . .
203 * }
204 * }
205 * </pre></blockquote>
206 *
207 * <h3> <a id="binary-name">Binary names</a> </h3>
208 *
209 * <p> Any class name provided as a {@code String} parameter to methods in
210 * {@code ClassLoader} must be a binary name as defined by
211 * <cite>The Java Language Specification</cite>.
212 *
213 * <p> Examples of valid class names include:
214 * <blockquote><pre>
215 * "java.lang.String"
216 * "javax.swing.JSpinner$DefaultEditor"
217 * "java.security.KeyStore$Builder$FileBuilder$1"
218 * "java.net.URLClassLoader$3$1"
219 * </pre></blockquote>
220 *
221 * <p> Any package name provided as a {@code String} parameter to methods in
222 * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
223 * or a fully qualified name as defined by
224 * <cite>The Java Language Specification</cite>.
225 *
226 * @jls 6.7 Fully Qualified Names
227 * @jls 13.1 The Form of a Binary
228 * @see #resolveClass(Class)
229 * @since 1.0
230 */
231 public abstract class ClassLoader {
232
233 private static native void registerNatives();
234 static {
235 registerNatives();
236 }
237
238 // The parent class loader for delegation
239 // Note: VM hardcoded the offset of this field, thus all new fields
240 // must be added *after* it.
241 private final ClassLoader parent;
242
243 // class loader name
244 private final String name;
245
246 // the unnamed module for this ClassLoader
247 private final Module unnamedModule;
248
249 // a string for exception message printing
250 private final String nameAndId;
251
252 /**
253 * Encapsulates the set of parallel capable loader types.
254 */
255 private static class ParallelLoaders {
256 private ParallelLoaders() {}
257
258 // the set of parallel capable loader types
259 private static final Set<Class<? extends ClassLoader>> loaderTypes =
260 Collections.newSetFromMap(new WeakHashMap<>());
261 static {
262 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
263 }
264
265 /**
266 * Registers the given class loader type as parallel capable.
267 * Returns {@code true} is successfully registered; {@code false} if
268 * loader's super class is not registered.
269 */
270 static boolean register(Class<? extends ClassLoader> c) {
271 synchronized (loaderTypes) {
272 if (loaderTypes.contains(c.getSuperclass())) {
273 // register the class loader as parallel capable
274 // if and only if all of its super classes are.
275 // Note: given current classloading sequence, if
276 // the immediate super class is parallel capable,
277 // all the super classes higher up must be too.
278 loaderTypes.add(c);
279 return true;
280 } else {
281 return false;
282 }
283 }
284 }
285
286 /**
287 * Returns {@code true} if the given class loader type is
288 * registered as parallel capable.
289 */
290 static boolean isRegistered(Class<? extends ClassLoader> c) {
291 synchronized (loaderTypes) {
292 return loaderTypes.contains(c);
293 }
294 }
295 }
296
297 // Maps class name to the corresponding lock object when the current
298 // class loader is parallel capable.
299 // Note: VM also uses this field to decide if the current class loader
300 // is parallel capable and the appropriate lock object for class loading.
301 private final ConcurrentHashMap<String, Object> parallelLockMap;
302
303 // Maps packages to certs
304 private final ConcurrentHashMap<String, Certificate[]> package2certs;
305
306 // Shared among all packages with unsigned classes
307 private static final Certificate[] nocerts = new Certificate[0];
308
309 // The classes loaded by this class loader. The only purpose of this table
310 // is to keep the classes from being GC'ed until the loader is GC'ed.
311 private final ArrayList<Class<?>> classes = new ArrayList<>();
312
313 // The "default" domain. Set as the default ProtectionDomain on newly
314 // created classes.
315 private final ProtectionDomain defaultDomain =
316 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
317 null, this, null);
318
319 // Invoked by the VM to record every loaded class with this loader.
320 void addClass(Class<?> c) {
321 synchronized (classes) {
322 classes.add(c);
323 }
324 }
325
326 // The packages defined in this class loader. Each package name is
327 // mapped to its corresponding NamedPackage object.
328 //
329 // The value is a Package object if ClassLoader::definePackage,
330 // Class::getPackage, ClassLoader::getDefinePackage(s) or
331 // Package::getPackage(s) method is called to define it.
332 // Otherwise, the value is a NamedPackage object.
333 private final ConcurrentHashMap<String, NamedPackage> packages
334 = new ConcurrentHashMap<>();
335
336 /*
337 * Returns a named package for the given module.
338 */
339 private NamedPackage getNamedPackage(String pn, Module m) {
340 NamedPackage p = packages.get(pn);
341 if (p == null) {
342 p = new NamedPackage(pn, m);
343
344 NamedPackage value = packages.putIfAbsent(pn, p);
345 if (value != null) {
346 // Package object already be defined for the named package
347 p = value;
348 // if definePackage is called by this class loader to define
349 // a package in a named module, this will return Package
350 // object of the same name. Package object may contain
351 // unexpected information but it does not impact the runtime.
352 // this assertion may be helpful for troubleshooting
353 assert value.module() == m;
354 }
355 }
356 return p;
357 }
358
359 private static Void checkCreateClassLoader() {
360 return checkCreateClassLoader(null);
361 }
362
363 private static Void checkCreateClassLoader(String name) {
364 if (name != null && name.isEmpty()) {
365 throw new IllegalArgumentException("name must be non-empty or null");
366 }
367
368 @SuppressWarnings("removal")
369 SecurityManager security = System.getSecurityManager();
370 if (security != null) {
371 security.checkCreateClassLoader();
372 }
373 return null;
374 }
375
376 private ClassLoader(Void unused, String name, ClassLoader parent) {
377 this.name = name;
378 this.parent = parent;
379 this.unnamedModule = new Module(this);
380 if (ParallelLoaders.isRegistered(this.getClass())) {
381 parallelLockMap = new ConcurrentHashMap<>();
382 assertionLock = new Object();
383 } else {
384 // no finer-grained lock; lock on the classloader instance
385 parallelLockMap = null;
386 assertionLock = this;
387 }
388 this.package2certs = new ConcurrentHashMap<>();
389 this.nameAndId = nameAndId(this);
390 }
391
392 /**
393 * If the defining loader has a name explicitly set then
394 * '<loader-name>' @<id>
395 * If the defining loader has no name then
396 * <qualified-class-name> @<id>
397 * If it's built-in loader then omit `@<id>` as there is only one instance.
398 */
399 private static String nameAndId(ClassLoader ld) {
400 String nid = ld.getName() != null ? "\'" + ld.getName() + "\'"
401 : ld.getClass().getName();
402 if (!(ld instanceof BuiltinClassLoader)) {
403 String id = Integer.toHexString(System.identityHashCode(ld));
404 nid = nid + " @" + id;
405 }
406 return nid;
407 }
408
409 // Returns nameAndId string for exception message printing
410 String nameAndId() {
411 return nameAndId;
412 }
413
414 /**
415 * Creates a new class loader of the specified name and using the
416 * specified parent class loader for delegation.
417 *
418 * @apiNote If the parent is specified as {@code null} (for the
419 * bootstrap class loader) then there is no guarantee that all platform
420 * classes are visible.
421 *
422 * @param name class loader name; or {@code null} if not named
423 * @param parent the parent class loader
424 *
425 * @throws IllegalArgumentException if the given name is empty.
426 *
427 * @throws SecurityException
428 * If a security manager exists and its
429 * {@link SecurityManager#checkCreateClassLoader()}
430 * method doesn't allow creation of a new class loader.
431 *
432 * @since 9
433 */
434 @SuppressWarnings("this-escape")
435 protected ClassLoader(String name, ClassLoader parent) {
436 this(checkCreateClassLoader(name), name, parent);
437 }
438
439 /**
440 * Creates a new class loader using the specified parent class loader for
441 * delegation.
442 *
443 * <p> If there is a security manager, its {@link
444 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
445 * is invoked. This may result in a security exception. </p>
446 *
447 * @apiNote If the parent is specified as {@code null} (for the
448 * bootstrap class loader) then there is no guarantee that all platform
449 * classes are visible.
450 *
451 * @param parent
452 * The parent class loader
453 *
454 * @throws SecurityException
455 * If a security manager exists and its
456 * {@code checkCreateClassLoader} method doesn't allow creation
457 * of a new class loader.
458 *
459 * @since 1.2
460 */
461 @SuppressWarnings("this-escape")
462 protected ClassLoader(ClassLoader parent) {
463 this(checkCreateClassLoader(), null, parent);
464 }
465
466 /**
467 * Creates a new class loader using the {@code ClassLoader} returned by
468 * the method {@link #getSystemClassLoader()
469 * getSystemClassLoader()} as the parent class loader.
470 *
471 * <p> If there is a security manager, its {@link
472 * SecurityManager#checkCreateClassLoader()
473 * checkCreateClassLoader} method is invoked. This may result in
474 * a security exception. </p>
475 *
476 * @throws SecurityException
477 * If a security manager exists and its
478 * {@code checkCreateClassLoader} method doesn't allow creation
479 * of a new class loader.
480 */
481 @SuppressWarnings("this-escape")
482 protected ClassLoader() {
483 this(checkCreateClassLoader(), null, getSystemClassLoader());
484 }
485
486 /**
487 * Returns the name of this class loader or {@code null} if
488 * this class loader is not named.
489 *
490 * @apiNote This method is non-final for compatibility. If this
491 * method is overridden, this method must return the same name
492 * as specified when this class loader was instantiated.
493 *
494 * @return name of this class loader; or {@code null} if
495 * this class loader is not named.
496 *
497 * @since 9
498 */
499 public String getName() {
500 return name;
501 }
502
503 // package-private used by StackTraceElement to avoid
504 // calling the overridable getName method
505 final String name() {
506 return name;
507 }
508
509 // -- Class --
510
511 /**
512 * Loads the class with the specified <a href="#binary-name">binary name</a>.
513 * This method searches for classes in the same manner as the {@link
514 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
515 * machine to resolve class references. Invoking this method is equivalent
516 * to invoking {@link #loadClass(String, boolean) loadClass(name,
517 * false)}.
518 *
519 * @param name
520 * The <a href="#binary-name">binary name</a> of the class
521 *
522 * @return The resulting {@code Class} object
523 *
524 * @throws ClassNotFoundException
525 * If the class was not found
526 */
527 public Class<?> loadClass(String name) throws ClassNotFoundException {
528 return loadClass(name, false);
529 }
530
531 /**
532 * Loads the class with the specified <a href="#binary-name">binary name</a>. The
533 * default implementation of this method searches for classes in the
534 * following order:
535 *
536 * <ol>
537 *
538 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
539 * has already been loaded. </p></li>
540 *
541 * <li><p> Invoke the {@link #loadClass(String) loadClass} method
542 * on the parent class loader. If the parent is {@code null} the class
543 * loader built into the virtual machine is used, instead. </p></li>
544 *
545 * <li><p> Invoke the {@link #findClass(String)} method to find the
546 * class. </p></li>
547 *
548 * </ol>
549 *
550 * <p> If the class was found using the above steps, and the
551 * {@code resolve} flag is true, this method will then invoke the {@link
552 * #resolveClass(Class)} method on the resulting {@code Class} object.
553 *
554 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
555 * #findClass(String)}, rather than this method. </p>
556 *
557 * <p> Unless overridden, this method synchronizes on the result of
558 * {@link #getClassLoadingLock getClassLoadingLock} method
559 * during the entire class loading process.
560 *
561 * @param name
562 * The <a href="#binary-name">binary name</a> of the class
563 *
564 * @param resolve
565 * If {@code true} then resolve the class
566 *
567 * @return The resulting {@code Class} object
568 *
569 * @throws ClassNotFoundException
570 * If the class could not be found
571 */
572 protected Class<?> loadClass(String name, boolean resolve)
573 throws ClassNotFoundException
574 {
575 synchronized (getClassLoadingLock(name)) {
576 // First, check if the class has already been loaded
577 Class<?> c = findLoadedClass(name);
578 if (c == null) {
579 long t0 = System.nanoTime();
580 try {
581 if (parent != null) {
582 c = parent.loadClass(name, false);
583 } else {
584 c = findBootstrapClassOrNull(name);
585 }
586 } catch (ClassNotFoundException e) {
587 // ClassNotFoundException thrown if class not found
588 // from the non-null parent class loader
589 }
590
591 if (c == null) {
592 // If still not found, then invoke findClass in order
593 // to find the class.
594 long t1 = System.nanoTime();
595 c = findClass(name);
596
597 // this is the defining class loader; record the stats
598 PerfCounter.getParentDelegationTime().addTime(t1 - t0);
599 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
600 PerfCounter.getFindClasses().increment();
601 }
602 }
603 if (resolve) {
604 resolveClass(c);
605 }
606 return c;
607 }
608 }
609
610 /**
611 * Loads the class with the specified <a href="#binary-name">binary name</a>
612 * in a module defined to this class loader. This method returns {@code null}
613 * if the class could not be found.
614 *
615 * @apiNote This method does not delegate to the parent class loader.
616 *
617 * @implSpec The default implementation of this method searches for classes
618 * in the following order:
619 *
620 * <ol>
621 * <li>Invoke {@link #findLoadedClass(String)} to check if the class
622 * has already been loaded.</li>
623 * <li>Invoke the {@link #findClass(String, String)} method to find the
624 * class in the given module.</li>
625 * </ol>
626 *
627 * @param module
628 * The module
629 * @param name
630 * The <a href="#binary-name">binary name</a> of the class
631 *
632 * @return The resulting {@code Class} object in a module defined by
633 * this class loader, or {@code null} if the class could not be found.
634 */
635 final Class<?> loadClass(Module module, String name) {
636 synchronized (getClassLoadingLock(name)) {
637 // First, check if the class has already been loaded
638 Class<?> c = findLoadedClass(name);
639 if (c == null) {
640 c = findClass(module.getName(), name);
641 }
642 if (c != null && c.getModule() == module) {
643 return c;
644 } else {
645 return null;
646 }
647 }
648 }
649
650 /**
651 * Returns the lock object for class loading operations.
652 *
653 * @implSpec
654 * If this {@code ClassLoader} object is registered as parallel capable,
655 * this method returns a dedicated object associated with the specified
656 * class name. Otherwise, this method returns this {@code ClassLoader} object.
657 *
658 * @apiNote
659 * This method allows parallel capable class loaders to implement
660 * finer-grained locking schemes such that multiple threads may load classes
661 * concurrently without deadlocks. For non-parallel-capable class loaders,
662 * the {@code ClassLoader} object is synchronized on during the class loading
663 * operations. Class loaders with non-hierarchical delegation should be
664 * {@linkplain #registerAsParallelCapable() registered as parallel capable}
665 * to prevent deadlocks.
666 *
667 * @param className
668 * The name of the to-be-loaded class
669 *
670 * @return the lock for class loading operations
671 *
672 * @throws NullPointerException
673 * If registered as parallel capable and {@code className} is {@code null}
674 *
675 * @see #loadClass(String, boolean)
676 *
677 * @since 1.7
678 */
679 protected Object getClassLoadingLock(String className) {
680 Object lock = this;
681 if (parallelLockMap != null) {
682 Object newLock = new Object();
683 lock = parallelLockMap.putIfAbsent(className, newLock);
684 if (lock == null) {
685 lock = newLock;
686 }
687 }
688 return lock;
689 }
690
691 // Invoked by the VM after loading class with this loader.
692 @SuppressWarnings("removal")
693 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
694 final SecurityManager sm = System.getSecurityManager();
695 if (sm != null) {
696 if (ReflectUtil.isNonPublicProxyClass(cls)) {
697 for (Class<?> intf: cls.getInterfaces()) {
698 checkPackageAccess(intf, pd);
699 }
700 return;
701 }
702
703 final String packageName = cls.getPackageName();
704 if (!packageName.isEmpty()) {
705 AccessController.doPrivileged(new PrivilegedAction<>() {
706 public Void run() {
707 sm.checkPackageAccess(packageName);
708 return null;
709 }
710 }, new AccessControlContext(new ProtectionDomain[] {pd}));
711 }
712 }
713 }
714
715 /**
716 * Finds the class with the specified <a href="#binary-name">binary name</a>.
717 * This method should be overridden by class loader implementations that
718 * follow the delegation model for loading classes, and will be invoked by
719 * the {@link #loadClass loadClass} method after checking the
720 * parent class loader for the requested class.
721 *
722 * @implSpec The default implementation throws {@code ClassNotFoundException}.
723 *
724 * @param name
725 * The <a href="#binary-name">binary name</a> of the class
726 *
727 * @return The resulting {@code Class} object
728 *
729 * @throws ClassNotFoundException
730 * If the class could not be found
731 *
732 * @since 1.2
733 */
734 protected Class<?> findClass(String name) throws ClassNotFoundException {
735 throw new ClassNotFoundException(name);
736 }
737
738 /**
739 * Finds the class with the given <a href="#binary-name">binary name</a>
740 * in a module defined to this class loader.
741 * Class loader implementations that support loading from modules
742 * should override this method.
743 *
744 * @apiNote This method returns {@code null} rather than throwing
745 * {@code ClassNotFoundException} if the class could not be found.
746 *
747 * @implSpec The default implementation attempts to find the class by
748 * invoking {@link #findClass(String)} when the {@code moduleName} is
749 * {@code null}. It otherwise returns {@code null}.
750 *
751 * @param moduleName
752 * The module name; or {@code null} to find the class in the
753 * {@linkplain #getUnnamedModule() unnamed module} for this
754 * class loader
755 * @param name
756 * The <a href="#binary-name">binary name</a> of the class
757 *
758 * @return The resulting {@code Class} object, or {@code null}
759 * if the class could not be found.
760 *
761 * @since 9
762 */
763 protected Class<?> findClass(String moduleName, String name) {
764 if (moduleName == null) {
765 try {
766 return findClass(name);
767 } catch (ClassNotFoundException ignore) { }
768 }
769 return null;
770 }
771
772
773 /**
774 * Converts an array of bytes into an instance of class {@code Class}.
775 * Before the {@code Class} can be used it must be resolved. This method
776 * is deprecated in favor of the version that takes a <a
777 * href="#binary-name">binary name</a> as its first argument, and is more secure.
778 *
779 * @param b
780 * The bytes that make up the class data. The bytes in positions
781 * {@code off} through {@code off+len-1} should have the format
782 * of a valid class file as defined by
783 * <cite>The Java Virtual Machine Specification</cite>.
784 *
785 * @param off
786 * The start offset in {@code b} of the class data
787 *
788 * @param len
789 * The length of the class data
790 *
791 * @return The {@code Class} object that was created from the specified
792 * class data
793 *
794 * @throws ClassFormatError
795 * If the data did not contain a valid class
796 *
797 * @throws IndexOutOfBoundsException
798 * If either {@code off} or {@code len} is negative, or if
799 * {@code off+len} is greater than {@code b.length}.
800 *
801 * @throws SecurityException
802 * If an attempt is made to add this class to a package that
803 * contains classes that were signed by a different set of
804 * certificates than this class, or if an attempt is made
805 * to define a class in a package with a fully-qualified name
806 * that starts with "{@code java.}".
807 *
808 * @see #loadClass(String, boolean)
809 * @see #resolveClass(Class)
810 *
811 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
812 * defineClass(String, byte[], int, int)}
813 */
814 @Deprecated(since="1.1")
815 protected final Class<?> defineClass(byte[] b, int off, int len)
816 throws ClassFormatError
817 {
818 return defineClass(null, b, off, len, null);
819 }
820
821 /**
822 * Converts an array of bytes into an instance of class {@code Class}.
823 * Before the {@code Class} can be used it must be resolved.
824 *
825 * <p> This method assigns a default {@link java.security.ProtectionDomain
826 * ProtectionDomain} to the newly defined class. The
827 * {@code ProtectionDomain} is effectively granted the same set of
828 * permissions returned when {@link
829 * java.security.Policy#getPermissions(java.security.CodeSource)
830 * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
831 * is invoked. The default protection domain is created on the first invocation
832 * of {@link #defineClass(String, byte[], int, int) defineClass},
833 * and re-used on subsequent invocations.
834 *
835 * <p> To assign a specific {@code ProtectionDomain} to the class, use
836 * the {@link #defineClass(String, byte[], int, int,
837 * java.security.ProtectionDomain) defineClass} method that takes a
838 * {@code ProtectionDomain} as one of its arguments. </p>
839 *
840 * <p>
841 * This method defines a package in this class loader corresponding to the
842 * package of the {@code Class} (if such a package has not already been defined
843 * in this class loader). The name of the defined package is derived from
844 * the <a href="#binary-name">binary name</a> of the class specified by
845 * the byte array {@code b}.
846 * Other properties of the defined package are as specified by {@link Package}.
847 *
848 * @param name
849 * The expected <a href="#binary-name">binary name</a> of the class, or
850 * {@code null} if not known
851 *
852 * @param b
853 * The bytes that make up the class data. The bytes in positions
854 * {@code off} through {@code off+len-1} should have the format
855 * of a valid class file as defined by
856 * <cite>The Java Virtual Machine Specification</cite>.
857 *
858 * @param off
859 * The start offset in {@code b} of the class data
860 *
861 * @param len
862 * The length of the class data
863 *
864 * @return The {@code Class} object that was created from the specified
865 * class data.
866 *
867 * @throws ClassFormatError
868 * If the data did not contain a valid class
869 *
870 * @throws IndexOutOfBoundsException
871 * If either {@code off} or {@code len} is negative, or if
872 * {@code off+len} is greater than {@code b.length}.
873 *
874 * @throws SecurityException
875 * If an attempt is made to add this class to a package that
876 * contains classes that were signed by a different set of
877 * certificates than this class (which is unsigned), or if
878 * {@code name} begins with "{@code java.}".
879 *
880 * @see #loadClass(String, boolean)
881 * @see #resolveClass(Class)
882 * @see java.security.CodeSource
883 * @see java.security.SecureClassLoader
884 *
885 * @since 1.1
886 */
887 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
888 throws ClassFormatError
889 {
890 return defineClass(name, b, off, len, null);
891 }
892
893 /* Determine protection domain, and check that:
894 - not define java.* class,
895 - signer of this class matches signers for the rest of the classes in
896 package.
897 */
898 private ProtectionDomain preDefineClass(String name,
899 ProtectionDomain pd)
900 {
901 if (!checkName(name))
902 throw new NoClassDefFoundError("IllegalName: " + name);
903
904 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
905 // relies on the fact that spoofing is impossible if a class has a name
906 // of the form "java.*"
907 if ((name != null) && name.startsWith("java.")
908 && this != getBuiltinPlatformClassLoader()) {
909 throw new SecurityException
910 ("Prohibited package name: " +
911 name.substring(0, name.lastIndexOf('.')));
912 }
913 if (pd == null) {
914 pd = defaultDomain;
915 }
916
917 if (name != null) {
918 checkCerts(name, pd.getCodeSource());
919 }
920
921 return pd;
922 }
923
924 private String defineClassSourceLocation(ProtectionDomain pd) {
925 CodeSource cs = pd.getCodeSource();
926 String source = null;
927 if (cs != null && cs.getLocation() != null) {
928 source = cs.getLocation().toString();
929 }
930 return source;
931 }
932
933 private void postDefineClass(Class<?> c, ProtectionDomain pd) {
934 // define a named package, if not present
935 getNamedPackage(c.getPackageName(), c.getModule());
936
937 if (pd.getCodeSource() != null) {
938 Certificate certs[] = pd.getCodeSource().getCertificates();
939 if (certs != null)
940 setSigners(c, certs);
941 }
942 }
943
944 /**
945 * Converts an array of bytes into an instance of class {@code Class},
946 * with a given {@code ProtectionDomain}.
947 *
948 * <p> If the given {@code ProtectionDomain} is {@code null},
949 * then a default protection domain will be assigned to the class as specified
950 * in the documentation for {@link #defineClass(String, byte[], int, int)}.
951 * Before the class can be used it must be resolved.
952 *
953 * <p> The first class defined in a package determines the exact set of
954 * certificates that all subsequent classes defined in that package must
955 * contain. The set of certificates for a class is obtained from the
956 * {@link java.security.CodeSource CodeSource} within the
957 * {@code ProtectionDomain} of the class. Any classes added to that
958 * package must contain the same set of certificates or a
959 * {@code SecurityException} will be thrown. Note that if
960 * {@code name} is {@code null}, this check is not performed.
961 * You should always pass in the <a href="#binary-name">binary name</a> of the
962 * class you are defining as well as the bytes. This ensures that the
963 * class you are defining is indeed the class you think it is.
964 *
965 * <p> If the specified {@code name} begins with "{@code java.}", it can
966 * only be defined by the {@linkplain #getPlatformClassLoader()
967 * platform class loader} or its ancestors; otherwise {@code SecurityException}
968 * will be thrown. If {@code name} is not {@code null}, it must be equal to
969 * the <a href="#binary-name">binary name</a> of the class
970 * specified by the byte array {@code b}, otherwise a {@link
971 * NoClassDefFoundError NoClassDefFoundError} will be thrown.
972 *
973 * <p> This method defines a package in this class loader corresponding to the
974 * package of the {@code Class} (if such a package has not already been defined
975 * in this class loader). The name of the defined package is derived from
976 * the <a href="#binary-name">binary name</a> of the class specified by
977 * the byte array {@code b}.
978 * Other properties of the defined package are as specified by {@link Package}.
979 *
980 * @param name
981 * The expected <a href="#binary-name">binary name</a> of the class, or
982 * {@code null} if not known
983 *
984 * @param b
985 * The bytes that make up the class data. The bytes in positions
986 * {@code off} through {@code off+len-1} should have the format
987 * of a valid class file as defined by
988 * <cite>The Java Virtual Machine Specification</cite>.
989 *
990 * @param off
991 * The start offset in {@code b} of the class data
992 *
993 * @param len
994 * The length of the class data
995 *
996 * @param protectionDomain
997 * The {@code ProtectionDomain} of the class
998 *
999 * @return The {@code Class} object created from the data,
1000 * and {@code ProtectionDomain}.
1001 *
1002 * @throws ClassFormatError
1003 * If the data did not contain a valid class
1004 *
1005 * @throws NoClassDefFoundError
1006 * If {@code name} is not {@code null} and not equal to the
1007 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
1008 *
1009 * @throws IndexOutOfBoundsException
1010 * If either {@code off} or {@code len} is negative, or if
1011 * {@code off+len} is greater than {@code b.length}.
1012 *
1013 * @throws SecurityException
1014 * If an attempt is made to add this class to a package that
1015 * contains classes that were signed by a different set of
1016 * certificates than this class, or if {@code name} begins with
1017 * "{@code java.}" and this class loader is not the platform
1018 * class loader or its ancestor.
1019 */
1020 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
1021 ProtectionDomain protectionDomain)
1022 throws ClassFormatError
1023 {
1024 protectionDomain = preDefineClass(name, protectionDomain);
1025 String source = defineClassSourceLocation(protectionDomain);
1026 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
1027 postDefineClass(c, protectionDomain);
1028 return c;
1029 }
1030
1031 /**
1032 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
1033 * of class {@code Class}, with the given {@code ProtectionDomain}.
1034 * If the given {@code ProtectionDomain} is {@code null}, then a default
1035 * protection domain will be assigned to the class as
1036 * specified in the documentation for {@link #defineClass(String, byte[],
1037 * int, int)}. Before the class can be used it must be resolved.
1038 *
1039 * <p>The rules about the first class defined in a package determining the
1040 * set of certificates for the package, the restrictions on class names,
1041 * and the defined package of the class
1042 * are identical to those specified in the documentation for {@link
1043 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
1044 *
1045 * <p> An invocation of this method of the form
1046 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
1047 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
1048 * result as the statements
1049 *
1050 *<p> <code>
1051 * ...<br>
1052 * byte[] temp = new byte[bBuffer.{@link
1053 * java.nio.ByteBuffer#remaining remaining}()];<br>
1054 * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
1055 * get}(temp);<br>
1056 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
1057 * cl.defineClass}(name, temp, 0,
1058 * temp.length, pd);<br>
1059 * </code></p>
1060 *
1061 * @param name
1062 * The expected <a href="#binary-name">binary name</a>. of the class, or
1063 * {@code null} if not known
1064 *
1065 * @param b
1066 * The bytes that make up the class data. The bytes from positions
1067 * {@code b.position()} through {@code b.position() + b.limit() -1
1068 * } should have the format of a valid class file as defined by
1069 * <cite>The Java Virtual Machine Specification</cite>.
1070 *
1071 * @param protectionDomain
1072 * The {@code ProtectionDomain} of the class, or {@code null}.
1073 *
1074 * @return The {@code Class} object created from the data,
1075 * and {@code ProtectionDomain}.
1076 *
1077 * @throws ClassFormatError
1078 * If the data did not contain a valid class.
1079 *
1080 * @throws NoClassDefFoundError
1081 * If {@code name} is not {@code null} and not equal to the
1082 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
1083 *
1084 * @throws SecurityException
1085 * If an attempt is made to add this class to a package that
1086 * contains classes that were signed by a different set of
1087 * certificates than this class, or if {@code name} begins with
1088 * "{@code java.}".
1089 *
1090 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
1091 *
1092 * @since 1.5
1093 */
1094 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
1095 ProtectionDomain protectionDomain)
1096 throws ClassFormatError
1097 {
1098 int len = b.remaining();
1099
1100 // Use byte[] if not a direct ByteBuffer:
1101 if (!b.isDirect()) {
1102 if (b.hasArray()) {
1103 return defineClass(name, b.array(),
1104 b.position() + b.arrayOffset(), len,
1105 protectionDomain);
1106 } else {
1107 // no array, or read-only array
1108 byte[] tb = new byte[len];
1109 b.get(tb); // get bytes out of byte buffer.
1110 return defineClass(name, tb, 0, len, protectionDomain);
1111 }
1112 }
1113
1114 protectionDomain = preDefineClass(name, protectionDomain);
1115 String source = defineClassSourceLocation(protectionDomain);
1116 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
1117 postDefineClass(c, protectionDomain);
1118 return c;
1119 }
1120
1121 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
1122 ProtectionDomain pd, String source);
1123
1124 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
1125 int off, int len, ProtectionDomain pd,
1126 String source);
1127
1128 /**
1129 * Defines a class of the given flags via Lookup.defineClass.
1130 *
1131 * @param loader the defining loader
1132 * @param lookup nest host of the Class to be defined
1133 * @param name the binary name or {@code null} if not findable
1134 * @param b class bytes
1135 * @param off the start offset in {@code b} of the class bytes
1136 * @param len the length of the class bytes
1137 * @param pd protection domain
1138 * @param initialize initialize the class
1139 * @param flags flags
1140 * @param classData class data
1141 */
1142 static native Class<?> defineClass0(ClassLoader loader,
1143 Class<?> lookup,
1144 String name,
1145 byte[] b, int off, int len,
1146 ProtectionDomain pd,
1147 boolean initialize,
1148 int flags,
1149 Object classData);
1150
1151 // true if the name is null or has the potential to be a valid binary name
1152 private static boolean checkName(String name) {
1153 if ((name == null) || (name.isEmpty()))
1154 return true;
1155 if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
1156 return false;
1157 return true;
1158 }
1159
1160 private void checkCerts(String name, CodeSource cs) {
1161 int i = name.lastIndexOf('.');
1162 String pname = (i == -1) ? "" : name.substring(0, i);
1163
1164 Certificate[] certs = null;
1165 if (cs != null) {
1166 certs = cs.getCertificates();
1167 }
1168 certs = certs == null ? nocerts : certs;
1169 Certificate[] pcerts = package2certs.putIfAbsent(pname, certs);
1170 if (pcerts != null && !compareCerts(pcerts, certs)) {
1171 throw new SecurityException("class \"" + name
1172 + "\"'s signer information does not match signer information"
1173 + " of other classes in the same package");
1174 }
1175 }
1176
1177 /**
1178 * check to make sure the certs for the new class (certs) are the same as
1179 * the certs for the first class inserted in the package (pcerts)
1180 */
1181 private boolean compareCerts(Certificate[] pcerts, Certificate[] certs) {
1182 // empty array fast-path
1183 if (certs.length == 0)
1184 return pcerts.length == 0;
1185
1186 // the length must be the same at this point
1187 if (certs.length != pcerts.length)
1188 return false;
1189
1190 // go through and make sure all the certs in one array
1191 // are in the other and vice-versa.
1192 boolean match;
1193 for (Certificate cert : certs) {
1194 match = false;
1195 for (Certificate pcert : pcerts) {
1196 if (cert.equals(pcert)) {
1197 match = true;
1198 break;
1199 }
1200 }
1201 if (!match) return false;
1202 }
1203
1204 // now do the same for pcerts
1205 for (Certificate pcert : pcerts) {
1206 match = false;
1207 for (Certificate cert : certs) {
1208 if (pcert.equals(cert)) {
1209 match = true;
1210 break;
1211 }
1212 }
1213 if (!match) return false;
1214 }
1215
1216 return true;
1217 }
1218
1219 /**
1220 * Links the specified class. This (misleadingly named) method may be
1221 * used by a class loader to link a class. If the class {@code c} has
1222 * already been linked, then this method simply returns. Otherwise, the
1223 * class is linked as described in the "Execution" chapter of
1224 * <cite>The Java Language Specification</cite>.
1225 *
1226 * @param c
1227 * The class to link
1228 *
1229 * @throws NullPointerException
1230 * If {@code c} is {@code null}.
1231 *
1232 * @see #defineClass(String, byte[], int, int)
1233 */
1234 protected final void resolveClass(Class<?> c) {
1235 if (c == null) {
1236 throw new NullPointerException();
1237 }
1238 }
1239
1240 /**
1241 * Finds a class with the specified <a href="#binary-name">binary name</a>,
1242 * loading it if necessary.
1243 *
1244 * <p> This method loads the class through the system class loader (see
1245 * {@link #getSystemClassLoader()}). The {@code Class} object returned
1246 * might have more than one {@code ClassLoader} associated with it.
1247 * Subclasses of {@code ClassLoader} need not usually invoke this method,
1248 * because most class loaders need to override just {@link
1249 * #findClass(String)}. </p>
1250 *
1251 * @param name
1252 * The <a href="#binary-name">binary name</a> of the class
1253 *
1254 * @return The {@code Class} object for the specified {@code name}
1255 *
1256 * @throws ClassNotFoundException
1257 * If the class could not be found
1258 *
1259 * @see #ClassLoader(ClassLoader)
1260 * @see #getParent()
1261 */
1262 protected final Class<?> findSystemClass(String name)
1263 throws ClassNotFoundException
1264 {
1265 return getSystemClassLoader().loadClass(name);
1266 }
1267
1268 /**
1269 * Returns a class loaded by the bootstrap class loader;
1270 * or return null if not found.
1271 */
1272 static Class<?> findBootstrapClassOrNull(String name) {
1273 if (!checkName(name)) return null;
1274
1275 return findBootstrapClass(name);
1276 }
1277
1278 // return null if not found
1279 private static native Class<?> findBootstrapClass(String name);
1280
1281 /**
1282 * Returns the class with the given <a href="#binary-name">binary name</a> if this
1283 * loader has been recorded by the Java virtual machine as an initiating
1284 * loader of a class with that <a href="#binary-name">binary name</a>. Otherwise
1285 * {@code null} is returned.
1286 *
1287 * @param name
1288 * The <a href="#binary-name">binary name</a> of the class
1289 *
1290 * @return The {@code Class} object, or {@code null} if the class has
1291 * not been loaded
1292 *
1293 * @since 1.1
1294 */
1295 protected final Class<?> findLoadedClass(String name) {
1296 if (!checkName(name))
1297 return null;
1298 return findLoadedClass0(name);
1299 }
1300
1301 private final native Class<?> findLoadedClass0(String name);
1302
1303 /**
1304 * Sets the signers of a class. This should be invoked after defining a
1305 * class.
1306 *
1307 * @param c
1308 * The {@code Class} object
1309 *
1310 * @param signers
1311 * The signers for the class
1312 *
1313 * @since 1.1
1314 */
1315 protected final void setSigners(Class<?> c, Object[] signers) {
1316 c.setSigners(signers);
1317 }
1318
1319
1320 // -- Resources --
1321
1322 /**
1323 * Returns a URL to a resource in a module defined to this class loader.
1324 * Class loader implementations that support loading from modules
1325 * should override this method.
1326 *
1327 * @apiNote This method is the basis for the {@link
1328 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
1329 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
1330 * Module.getResourceAsStream} methods. It is not subject to the rules for
1331 * encapsulation specified by {@code Module.getResourceAsStream}.
1332 *
1333 * @implSpec The default implementation attempts to find the resource by
1334 * invoking {@link #findResource(String)} when the {@code moduleName} is
1335 * {@code null}. It otherwise returns {@code null}.
1336 *
1337 * @param moduleName
1338 * The module name; or {@code null} to find a resource in the
1339 * {@linkplain #getUnnamedModule() unnamed module} for this
1340 * class loader
1341 * @param name
1342 * The resource name
1343 *
1344 * @return A URL to the resource; {@code null} if the resource could not be
1345 * found, a URL could not be constructed to locate the resource,
1346 * access to the resource is denied by the security manager, or
1347 * there isn't a module of the given name defined to the class
1348 * loader.
1349 *
1350 * @throws IOException
1351 * If I/O errors occur
1352 *
1353 * @see java.lang.module.ModuleReader#find(String)
1354 * @since 9
1355 */
1356 protected URL findResource(String moduleName, String name) throws IOException {
1357 if (moduleName == null) {
1358 return findResource(name);
1359 } else {
1360 return null;
1361 }
1362 }
1363
1364 /**
1365 * Finds the resource with the given name. A resource is some data
1366 * (images, audio, text, etc) that can be accessed by class code in a way
1367 * that is independent of the location of the code.
1368 *
1369 * <p> The name of a resource is a '{@code /}'-separated path name that
1370 * identifies the resource. </p>
1371 *
1372 * <p> Resources in named modules are subject to the encapsulation rules
1373 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1374 * Additionally, and except for the special case where the resource has a
1375 * name ending with "{@code .class}", this method will only find resources in
1376 * packages of named modules when the package is {@link Module#isOpen(String)
1377 * opened} unconditionally (even if the caller of this method is in the
1378 * same module as the resource). </p>
1379 *
1380 * @implSpec The default implementation will first search the parent class
1381 * loader for the resource; if the parent is {@code null} the path of the
1382 * class loader built into the virtual machine is searched. If not found,
1383 * this method will invoke {@link #findResource(String)} to find the resource.
1384 *
1385 * @apiNote Where several modules are defined to the same class loader,
1386 * and where more than one module contains a resource with the given name,
1387 * then the ordering that modules are searched is not specified and may be
1388 * very unpredictable.
1389 * When overriding this method it is recommended that an implementation
1390 * ensures that any delegation is consistent with the {@link
1391 * #getResources(java.lang.String) getResources(String)} method.
1392 *
1393 * @param name
1394 * The resource name
1395 *
1396 * @return {@code URL} object for reading the resource; {@code null} if
1397 * the resource could not be found, a {@code URL} could not be
1398 * constructed to locate the resource, the resource is in a package
1399 * that is not opened unconditionally, or access to the resource is
1400 * denied by the security manager.
1401 *
1402 * @throws NullPointerException If {@code name} is {@code null}
1403 *
1404 * @since 1.1
1405 */
1406 public URL getResource(String name) {
1407 Objects.requireNonNull(name);
1408 URL url;
1409 if (parent != null) {
1410 url = parent.getResource(name);
1411 } else {
1412 url = BootLoader.findResource(name);
1413 }
1414 if (url == null) {
1415 url = findResource(name);
1416 }
1417 return url;
1418 }
1419
1420 /**
1421 * Finds all the resources with the given name. A resource is some data
1422 * (images, audio, text, etc) that can be accessed by class code in a way
1423 * that is independent of the location of the code.
1424 *
1425 * <p> The name of a resource is a {@code /}-separated path name that
1426 * identifies the resource. </p>
1427 *
1428 * <p> Resources in named modules are subject to the encapsulation rules
1429 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1430 * Additionally, and except for the special case where the resource has a
1431 * name ending with "{@code .class}", this method will only find resources in
1432 * packages of named modules when the package is {@link Module#isOpen(String)
1433 * opened} unconditionally (even if the caller of this method is in the
1434 * same module as the resource). </p>
1435 *
1436 * @implSpec The default implementation will first search the parent class
1437 * loader for the resource; if the parent is {@code null} the path of the
1438 * class loader built into the virtual machine is searched. It then
1439 * invokes {@link #findResources(String)} to find the resources with the
1440 * name in this class loader. It returns an enumeration whose elements
1441 * are the URLs found by searching the parent class loader followed by
1442 * the elements found with {@code findResources}.
1443 *
1444 * @apiNote Where several modules are defined to the same class loader,
1445 * and where more than one module contains a resource with the given name,
1446 * then the ordering is not specified and may be very unpredictable.
1447 * When overriding this method it is recommended that an
1448 * implementation ensures that any delegation is consistent with the {@link
1449 * #getResource(java.lang.String) getResource(String)} method. This should
1450 * ensure that the first element returned by the Enumeration's
1451 * {@code nextElement} method is the same resource that the
1452 * {@code getResource(String)} method would return.
1453 *
1454 * @param name
1455 * The resource name
1456 *
1457 * @return An enumeration of {@link java.net.URL URL} objects for the
1458 * resource. If no resources could be found, the enumeration will
1459 * be empty. Resources for which a {@code URL} cannot be
1460 * constructed, are in a package that is not opened
1461 * unconditionally, or access to the resource is denied by the
1462 * security manager, are not returned in the enumeration.
1463 *
1464 * @throws IOException
1465 * If I/O errors occur
1466 * @throws NullPointerException If {@code name} is {@code null}
1467 *
1468 * @since 1.2
1469 */
1470 public Enumeration<URL> getResources(String name) throws IOException {
1471 Objects.requireNonNull(name);
1472 @SuppressWarnings("unchecked")
1473 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1474 if (parent != null) {
1475 tmp[0] = parent.getResources(name);
1476 } else {
1477 tmp[0] = BootLoader.findResources(name);
1478 }
1479 tmp[1] = findResources(name);
1480
1481 return new CompoundEnumeration<>(tmp);
1482 }
1483
1484 /**
1485 * Returns a stream whose elements are the URLs of all the resources with
1486 * the given name. A resource is some data (images, audio, text, etc) that
1487 * can be accessed by class code in a way that is independent of the
1488 * location of the code.
1489 *
1490 * <p> The name of a resource is a {@code /}-separated path name that
1491 * identifies the resource.
1492 *
1493 * <p> The resources will be located when the returned stream is evaluated.
1494 * If the evaluation results in an {@code IOException} then the I/O
1495 * exception is wrapped in an {@link UncheckedIOException} that is then
1496 * thrown.
1497 *
1498 * <p> Resources in named modules are subject to the encapsulation rules
1499 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1500 * Additionally, and except for the special case where the resource has a
1501 * name ending with "{@code .class}", this method will only find resources in
1502 * packages of named modules when the package is {@link Module#isOpen(String)
1503 * opened} unconditionally (even if the caller of this method is in the
1504 * same module as the resource). </p>
1505 *
1506 * @implSpec The default implementation invokes {@link #getResources(String)
1507 * getResources} to find all the resources with the given name and returns
1508 * a stream with the elements in the enumeration as the source.
1509 *
1510 * @apiNote When overriding this method it is recommended that an
1511 * implementation ensures that any delegation is consistent with the {@link
1512 * #getResource(java.lang.String) getResource(String)} method. This should
1513 * ensure that the first element returned by the stream is the same
1514 * resource that the {@code getResource(String)} method would return.
1515 *
1516 * @param name
1517 * The resource name
1518 *
1519 * @return A stream of resource {@link java.net.URL URL} objects. If no
1520 * resources could be found, the stream will be empty. Resources
1521 * for which a {@code URL} cannot be constructed, are in a package
1522 * that is not opened unconditionally, or access to the resource
1523 * is denied by the security manager, will not be in the stream.
1524 *
1525 * @throws NullPointerException If {@code name} is {@code null}
1526 *
1527 * @since 9
1528 */
1529 public Stream<URL> resources(String name) {
1530 Objects.requireNonNull(name);
1531 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
1532 Supplier<Spliterator<URL>> si = () -> {
1533 try {
1534 return Spliterators.spliteratorUnknownSize(
1535 getResources(name).asIterator(), characteristics);
1536 } catch (IOException e) {
1537 throw new UncheckedIOException(e);
1538 }
1539 };
1540 return StreamSupport.stream(si, characteristics, false);
1541 }
1542
1543 /**
1544 * Finds the resource with the given name. Class loader implementations
1545 * should override this method.
1546 *
1547 * <p> For resources in named modules then the method must implement the
1548 * rules for encapsulation specified in the {@code Module} {@link
1549 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1550 * it must not find non-"{@code .class}" resources in packages of named
1551 * modules unless the package is {@link Module#isOpen(String) opened}
1552 * unconditionally. </p>
1553 *
1554 * @implSpec The default implementation returns {@code null}.
1555 *
1556 * @param name
1557 * The resource name
1558 *
1559 * @return {@code URL} object for reading the resource; {@code null} if
1560 * the resource could not be found, a {@code URL} could not be
1561 * constructed to locate the resource, the resource is in a package
1562 * that is not opened unconditionally, or access to the resource is
1563 * denied by the security manager.
1564 *
1565 * @since 1.2
1566 */
1567 protected URL findResource(String name) {
1568 return null;
1569 }
1570
1571 /**
1572 * Returns an enumeration of {@link java.net.URL URL} objects
1573 * representing all the resources with the given name. Class loader
1574 * implementations should override this method.
1575 *
1576 * <p> For resources in named modules then the method must implement the
1577 * rules for encapsulation specified in the {@code Module} {@link
1578 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1579 * it must not find non-"{@code .class}" resources in packages of named
1580 * modules unless the package is {@link Module#isOpen(String) opened}
1581 * unconditionally. </p>
1582 *
1583 * @implSpec The default implementation returns an enumeration that
1584 * contains no elements.
1585 *
1586 * @param name
1587 * The resource name
1588 *
1589 * @return An enumeration of {@link java.net.URL URL} objects for
1590 * the resource. If no resources could be found, the enumeration
1591 * will be empty. Resources for which a {@code URL} cannot be
1592 * constructed, are in a package that is not opened unconditionally,
1593 * or access to the resource is denied by the security manager,
1594 * are not returned in the enumeration.
1595 *
1596 * @throws IOException
1597 * If I/O errors occur
1598 *
1599 * @since 1.2
1600 */
1601 protected Enumeration<URL> findResources(String name) throws IOException {
1602 return Collections.emptyEnumeration();
1603 }
1604
1605 /**
1606 * Registers the caller as
1607 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
1608 * The registration succeeds if and only if all of the following
1609 * conditions are met:
1610 * <ol>
1611 * <li> no instance of the caller has been created</li>
1612 * <li> all of the super classes (except class Object) of the caller are
1613 * registered as parallel capable</li>
1614 * </ol>
1615 * <p>Note that once a class loader is registered as parallel capable, there
1616 * is no way to change it back.</p>
1617 * <p>
1618 * In cases where this method is called from a context where the caller is
1619 * not a subclass of {@code ClassLoader} or there is no caller frame on the
1620 * stack (e.g. when called directly from a JNI attached thread),
1621 * {@code IllegalCallerException} is thrown.
1622 * </p>
1623 *
1624 * @return {@code true} if the caller is successfully registered as
1625 * parallel capable and {@code false} if otherwise.
1626 * @throws IllegalCallerException if the caller is not a subclass of {@code ClassLoader}
1627 *
1628 * @see #isRegisteredAsParallelCapable()
1629 *
1630 * @since 1.7
1631 */
1632 @CallerSensitive
1633 protected static boolean registerAsParallelCapable() {
1634 return registerAsParallelCapable(Reflection.getCallerClass());
1635 }
1636
1637 // Caller-sensitive adapter method for reflective invocation
1638 @CallerSensitiveAdapter
1639 private static boolean registerAsParallelCapable(Class<?> caller) {
1640 if ((caller == null) || !ClassLoader.class.isAssignableFrom(caller)) {
1641 throw new IllegalCallerException(caller + " not a subclass of ClassLoader");
1642 }
1643 return ParallelLoaders.register(caller.asSubclass(ClassLoader.class));
1644 }
1645
1646 /**
1647 * Returns {@code true} if this class loader is registered as
1648 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
1649 * {@code false}.
1650 *
1651 * @return {@code true} if this class loader is parallel capable,
1652 * otherwise {@code false}.
1653 *
1654 * @see #registerAsParallelCapable()
1655 *
1656 * @since 9
1657 */
1658 public final boolean isRegisteredAsParallelCapable() {
1659 return ParallelLoaders.isRegistered(this.getClass());
1660 }
1661
1662 /**
1663 * Find a resource of the specified name from the search path used to load
1664 * classes. This method locates the resource through the system class
1665 * loader (see {@link #getSystemClassLoader()}).
1666 *
1667 * <p> Resources in named modules are subject to the encapsulation rules
1668 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1669 * Additionally, and except for the special case where the resource has a
1670 * name ending with "{@code .class}", this method will only find resources in
1671 * packages of named modules when the package is {@link Module#isOpen(String)
1672 * opened} unconditionally. </p>
1673 *
1674 * @param name
1675 * The resource name
1676 *
1677 * @return A {@link java.net.URL URL} to the resource; {@code
1678 * null} if the resource could not be found, a URL could not be
1679 * constructed to locate the resource, the resource is in a package
1680 * that is not opened unconditionally or access to the resource is
1681 * denied by the security manager.
1682 *
1683 * @since 1.1
1684 */
1685 public static URL getSystemResource(String name) {
1686 return getSystemClassLoader().getResource(name);
1687 }
1688
1689 /**
1690 * Finds all resources of the specified name from the search path used to
1691 * load classes. The resources thus found are returned as an
1692 * {@link java.util.Enumeration Enumeration} of {@link
1693 * java.net.URL URL} objects.
1694 *
1695 * <p> The search order is described in the documentation for {@link
1696 * #getSystemResource(String)}. </p>
1697 *
1698 * <p> Resources in named modules are subject to the encapsulation rules
1699 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1700 * Additionally, and except for the special case where the resource has a
1701 * name ending with "{@code .class}", this method will only find resources in
1702 * packages of named modules when the package is {@link Module#isOpen(String)
1703 * opened} unconditionally. </p>
1704 *
1705 * @param name
1706 * The resource name
1707 *
1708 * @return An enumeration of {@link java.net.URL URL} objects for
1709 * the resource. If no resources could be found, the enumeration
1710 * will be empty. Resources for which a {@code URL} cannot be
1711 * constructed, are in a package that is not opened unconditionally,
1712 * or access to the resource is denied by the security manager,
1713 * are not returned in the enumeration.
1714 *
1715 * @throws IOException
1716 * If I/O errors occur
1717 *
1718 * @since 1.2
1719 */
1720 public static Enumeration<URL> getSystemResources(String name)
1721 throws IOException
1722 {
1723 return getSystemClassLoader().getResources(name);
1724 }
1725
1726 /**
1727 * Returns an input stream for reading the specified resource.
1728 *
1729 * <p> The search order is described in the documentation for {@link
1730 * #getResource(String)}. </p>
1731 *
1732 * <p> Resources in named modules are subject to the encapsulation rules
1733 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1734 * Additionally, and except for the special case where the resource has a
1735 * name ending with "{@code .class}", this method will only find resources in
1736 * packages of named modules when the package is {@link Module#isOpen(String)
1737 * opened} unconditionally. </p>
1738 *
1739 * @param name
1740 * The resource name
1741 *
1742 * @return An input stream for reading the resource; {@code null} if the
1743 * resource could not be found, the resource is in a package that
1744 * is not opened unconditionally, or access to the resource is
1745 * denied by the security manager.
1746 *
1747 * @throws NullPointerException If {@code name} is {@code null}
1748 *
1749 * @since 1.1
1750 */
1751 public InputStream getResourceAsStream(String name) {
1752 Objects.requireNonNull(name);
1753 URL url = getResource(name);
1754 try {
1755 return url != null ? url.openStream() : null;
1756 } catch (IOException e) {
1757 return null;
1758 }
1759 }
1760
1761 /**
1762 * Open for reading, a resource of the specified name from the search path
1763 * used to load classes. This method locates the resource through the
1764 * system class loader (see {@link #getSystemClassLoader()}).
1765 *
1766 * <p> Resources in named modules are subject to the encapsulation rules
1767 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1768 * Additionally, and except for the special case where the resource has a
1769 * name ending with "{@code .class}", this method will only find resources in
1770 * packages of named modules when the package is {@link Module#isOpen(String)
1771 * opened} unconditionally. </p>
1772 *
1773 * @param name
1774 * The resource name
1775 *
1776 * @return An input stream for reading the resource; {@code null} if the
1777 * resource could not be found, the resource is in a package that
1778 * is not opened unconditionally, or access to the resource is
1779 * denied by the security manager.
1780 *
1781 * @since 1.1
1782 */
1783 public static InputStream getSystemResourceAsStream(String name) {
1784 URL url = getSystemResource(name);
1785 try {
1786 return url != null ? url.openStream() : null;
1787 } catch (IOException e) {
1788 return null;
1789 }
1790 }
1791
1792
1793 // -- Hierarchy --
1794
1795 /**
1796 * Returns the parent class loader for delegation. Some implementations may
1797 * use {@code null} to represent the bootstrap class loader. This method
1798 * will return {@code null} in such implementations if this class loader's
1799 * parent is the bootstrap class loader.
1800 *
1801 * @return The parent {@code ClassLoader}
1802 *
1803 * @throws SecurityException
1804 * If a security manager is present, and the caller's class loader
1805 * is not {@code null} and is not an ancestor of this class loader,
1806 * and the caller does not have the
1807 * {@link RuntimePermission}{@code ("getClassLoader")}
1808 *
1809 * @since 1.2
1810 */
1811 @CallerSensitive
1812 public final ClassLoader getParent() {
1813 if (parent == null)
1814 return null;
1815 @SuppressWarnings("removal")
1816 SecurityManager sm = System.getSecurityManager();
1817 if (sm != null) {
1818 // Check access to the parent class loader
1819 // If the caller's class loader is same as this class loader,
1820 // permission check is performed.
1821 checkClassLoaderPermission(parent, Reflection.getCallerClass());
1822 }
1823 return parent;
1824 }
1825
1826 /**
1827 * Returns the unnamed {@code Module} for this class loader.
1828 *
1829 * @return The unnamed Module for this class loader
1830 *
1831 * @see Module#isNamed()
1832 * @since 9
1833 */
1834 public final Module getUnnamedModule() {
1835 return unnamedModule;
1836 }
1837
1838 /**
1839 * Returns the platform class loader. All
1840 * <a href="#builtinLoaders">platform classes</a> are visible to
1841 * the platform class loader.
1842 *
1843 * @implNote The name of the builtin platform class loader is
1844 * {@code "platform"}.
1845 *
1846 * @return The platform {@code ClassLoader}.
1847 *
1848 * @throws SecurityException
1849 * If a security manager is present, and the caller's class loader is
1850 * not {@code null}, and the caller's class loader is not the same
1851 * as or an ancestor of the platform class loader,
1852 * and the caller does not have the
1853 * {@link RuntimePermission}{@code ("getClassLoader")}
1854 *
1855 * @since 9
1856 */
1857 @CallerSensitive
1858 public static ClassLoader getPlatformClassLoader() {
1859 @SuppressWarnings("removal")
1860 SecurityManager sm = System.getSecurityManager();
1861 ClassLoader loader = getBuiltinPlatformClassLoader();
1862 if (sm != null) {
1863 checkClassLoaderPermission(loader, Reflection.getCallerClass());
1864 }
1865 return loader;
1866 }
1867
1868 /**
1869 * Returns the system class loader. This is the default
1870 * delegation parent for new {@code ClassLoader} instances, and is
1871 * typically the class loader used to start the application.
1872 *
1873 * <p> This method is first invoked early in the runtime's startup
1874 * sequence, at which point it creates the system class loader. This
1875 * class loader will be the context class loader for the main application
1876 * thread (for example, the thread that invokes the {@code main} method of
1877 * the main class).
1878 *
1879 * <p> The default system class loader is an implementation-dependent
1880 * instance of this class.
1881 *
1882 * <p> If the system property "{@systemProperty java.system.class.loader}"
1883 * is defined when this method is first invoked then the value of that
1884 * property is taken to be the name of a class that will be returned as the
1885 * system class loader. The class is loaded using the default system class
1886 * loader and must define a public constructor that takes a single parameter
1887 * of type {@code ClassLoader} which is used as the delegation parent. An
1888 * instance is then created using this constructor with the default system
1889 * class loader as the parameter. The resulting class loader is defined
1890 * to be the system class loader. During construction, the class loader
1891 * should take great care to avoid calling {@code getSystemClassLoader()}.
1892 * If circular initialization of the system class loader is detected then
1893 * an {@code IllegalStateException} is thrown.
1894 *
1895 * @implNote The system property to override the system class loader is not
1896 * examined until the VM is almost fully initialized. Code that executes
1897 * this method during startup should take care not to cache the return
1898 * value until the system is fully initialized.
1899 *
1900 * <p> The name of the built-in system class loader is {@code "app"}.
1901 * The system property "{@code java.class.path}" is read during early
1902 * initialization of the VM to determine the class path.
1903 * An empty value of "{@code java.class.path}" property is interpreted
1904 * differently depending on whether the initial module (the module
1905 * containing the main class) is named or unnamed:
1906 * If named, the built-in system class loader will have no class path and
1907 * will search for classes and resources using the application module path;
1908 * otherwise, if unnamed, it will set the class path to the current
1909 * working directory.
1910 *
1911 * <p> JAR files on the class path may contain a {@code Class-Path} manifest
1912 * attribute to specify dependent JAR files to be included in the class path.
1913 * {@code Class-Path} entries must meet certain conditions for validity (see
1914 * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute">
1915 * JAR File Specification</a> for details). Invalid {@code Class-Path}
1916 * entries are ignored. For debugging purposes, ignored entries can be
1917 * printed to the console if the
1918 * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system
1919 * property is set to {@code true}.
1920 *
1921 * @return The system {@code ClassLoader}
1922 *
1923 * @throws SecurityException
1924 * If a security manager is present, and the caller's class loader
1925 * is not {@code null} and is not the same as or an ancestor of the
1926 * system class loader, and the caller does not have the
1927 * {@link RuntimePermission}{@code ("getClassLoader")}
1928 *
1929 * @throws IllegalStateException
1930 * If invoked recursively during the construction of the class
1931 * loader specified by the "{@code java.system.class.loader}"
1932 * property.
1933 *
1934 * @throws Error
1935 * If the system property "{@code java.system.class.loader}"
1936 * is defined but the named class could not be loaded, the
1937 * provider class does not define the required constructor, or an
1938 * exception is thrown by that constructor when it is invoked. The
1939 * underlying cause of the error can be retrieved via the
1940 * {@link Throwable#getCause()} method.
1941 */
1942 @CallerSensitive
1943 public static ClassLoader getSystemClassLoader() {
1944 switch (VM.initLevel()) {
1945 case 0:
1946 case 1:
1947 case 2:
1948 // the system class loader is the built-in app class loader during startup
1949 return getBuiltinAppClassLoader();
1950 case 3:
1951 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
1952 throw new IllegalStateException(msg);
1953 default:
1954 // system fully initialized
1955 assert VM.isBooted() && scl != null;
1956 @SuppressWarnings("removal")
1957 SecurityManager sm = System.getSecurityManager();
1958 if (sm != null) {
1959 checkClassLoaderPermission(scl, Reflection.getCallerClass());
1960 }
1961 return scl;
1962 }
1963 }
1964
1965 static ClassLoader getBuiltinPlatformClassLoader() {
1966 return ClassLoaders.platformClassLoader();
1967 }
1968
1969 static ClassLoader getBuiltinAppClassLoader() {
1970 return ClassLoaders.appClassLoader();
1971 }
1972
1973 /*
1974 * Initialize the system class loader that may be a custom class on the
1975 * application class path or application module path.
1976 *
1977 * @see java.lang.System#initPhase3
1978 */
1979 static synchronized ClassLoader initSystemClassLoader() {
1980 if (VM.initLevel() != 3) {
1981 throw new InternalError("system class loader cannot be set at initLevel " +
1982 VM.initLevel());
1983 }
1984
1985 // detect recursive initialization
1986 if (scl != null) {
1987 throw new IllegalStateException("recursive invocation");
1988 }
1989
1990 ClassLoader builtinLoader = getBuiltinAppClassLoader();
1991
1992 // All are privileged frames. No need to call doPrivileged.
1993 String cn = System.getProperty("java.system.class.loader");
1994 if (cn != null) {
1995 try {
1996 // custom class loader is only supported to be loaded from unnamed module
1997 Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
1998 .getDeclaredConstructor(ClassLoader.class);
1999 scl = (ClassLoader) ctor.newInstance(builtinLoader);
2000 } catch (Exception e) {
2001 Throwable cause = e;
2002 if (e instanceof InvocationTargetException) {
2003 cause = e.getCause();
2004 if (cause instanceof Error) {
2005 throw (Error) cause;
2006 }
2007 }
2008 if (cause instanceof RuntimeException) {
2009 throw (RuntimeException) cause;
2010 }
2011 throw new Error(cause.getMessage(), cause);
2012 }
2013 } else {
2014 scl = builtinLoader;
2015 }
2016 return scl;
2017 }
2018
2019 // Returns true if the specified class loader can be found in this class
2020 // loader's delegation chain.
2021 boolean isAncestor(ClassLoader cl) {
2022 ClassLoader acl = this;
2023 do {
2024 acl = acl.parent;
2025 if (cl == acl) {
2026 return true;
2027 }
2028 } while (acl != null);
2029 return false;
2030 }
2031
2032 // Tests if class loader access requires "getClassLoader" permission
2033 // check. A class loader 'from' can access class loader 'to' if
2034 // class loader 'from' is same as class loader 'to' or an ancestor
2035 // of 'to'. The class loader in a system domain can access
2036 // any class loader.
2037 private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
2038 ClassLoader to)
2039 {
2040 if (from == to)
2041 return false;
2042
2043 if (from == null)
2044 return false;
2045
2046 return !to.isAncestor(from);
2047 }
2048
2049 // Returns the class's class loader, or null if none.
2050 static ClassLoader getClassLoader(Class<?> caller) {
2051 // This can be null if the VM is requesting it
2052 if (caller == null) {
2053 return null;
2054 }
2055 // Circumvent security check since this is package-private
2056 return caller.getClassLoader0();
2057 }
2058
2059 /*
2060 * Checks RuntimePermission("getClassLoader") permission
2061 * if caller's class loader is not null and caller's class loader
2062 * is not the same as or an ancestor of the given cl argument.
2063 */
2064 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
2065 @SuppressWarnings("removal")
2066 SecurityManager sm = System.getSecurityManager();
2067 if (sm != null) {
2068 // caller can be null if the VM is requesting it
2069 ClassLoader ccl = getClassLoader(caller);
2070 if (needsClassLoaderPermissionCheck(ccl, cl)) {
2071 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
2072 }
2073 }
2074 }
2075
2076 // The system class loader
2077 // @GuardedBy("ClassLoader.class")
2078 private static volatile ClassLoader scl;
2079
2080 // -- Package --
2081
2082 /**
2083 * Define a Package of the given Class object.
2084 *
2085 * If the given class represents an array type, a primitive type or void,
2086 * this method returns {@code null}.
2087 *
2088 * This method does not throw IllegalArgumentException.
2089 */
2090 Package definePackage(Class<?> c) {
2091 if (c.isPrimitive() || c.isArray()) {
2092 return null;
2093 }
2094
2095 return definePackage(c.getPackageName(), c.getModule());
2096 }
2097
2098 /**
2099 * Defines a Package of the given name and module
2100 *
2101 * This method does not throw IllegalArgumentException.
2102 *
2103 * @param name package name
2104 * @param m module
2105 */
2106 Package definePackage(String name, Module m) {
2107 if (name.isEmpty() && m.isNamed()) {
2108 throw new InternalError("unnamed package in " + m);
2109 }
2110
2111 // check if Package object is already defined
2112 NamedPackage pkg = packages.get(name);
2113 if (pkg instanceof Package)
2114 return (Package)pkg;
2115
2116 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
2117 }
2118
2119 /*
2120 * Returns a Package object for the named package
2121 */
2122 private Package toPackage(String name, NamedPackage p, Module m) {
2123 // define Package object if the named package is not yet defined
2124 if (p == null)
2125 return NamedPackage.toPackage(name, m);
2126
2127 // otherwise, replace the NamedPackage object with Package object
2128 if (p instanceof Package)
2129 return (Package)p;
2130
2131 return NamedPackage.toPackage(p.packageName(), p.module());
2132 }
2133
2134 /**
2135 * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}.
2136 * <p>
2137 * <a href="#binary-name">Package names</a> must be unique within a class loader and
2138 * cannot be redefined or changed once created.
2139 * <p>
2140 * If a class loader wishes to define a package with specific properties,
2141 * such as version information, then the class loader should call this
2142 * {@code definePackage} method before calling {@code defineClass}.
2143 * Otherwise, the
2144 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
2145 * method will define a package in this class loader corresponding to the package
2146 * of the newly defined class; the properties of this defined package are
2147 * specified by {@link Package}.
2148 *
2149 * @apiNote
2150 * A class loader that wishes to define a package for classes in a JAR
2151 * typically uses the specification and implementation titles, versions, and
2152 * vendors from the JAR's manifest. If the package is specified as
2153 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
2154 * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
2155 * If classes of package {@code 'p'} defined by this class loader
2156 * are loaded from multiple JARs, the {@code Package} object may contain
2157 * different information depending on the first class of package {@code 'p'}
2158 * defined and which JAR's manifest is read first to explicitly define
2159 * package {@code 'p'}.
2160 *
2161 * <p> It is strongly recommended that a class loader does not call this
2162 * method to explicitly define packages in <em>named modules</em>; instead,
2163 * the package will be automatically defined when a class is {@linkplain
2164 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
2165 * If it is desirable to define {@code Package} explicitly, it should ensure
2166 * that all packages in a named module are defined with the properties
2167 * specified by {@link Package}. Otherwise, some {@code Package} objects
2168 * in a named module may be for example sealed with different seal base.
2169 *
2170 * @param name
2171 * The <a href="#binary-name">package name</a>
2172 *
2173 * @param specTitle
2174 * The specification title
2175 *
2176 * @param specVersion
2177 * The specification version
2178 *
2179 * @param specVendor
2180 * The specification vendor
2181 *
2182 * @param implTitle
2183 * The implementation title
2184 *
2185 * @param implVersion
2186 * The implementation version
2187 *
2188 * @param implVendor
2189 * The implementation vendor
2190 *
2191 * @param sealBase
2192 * If not {@code null}, then this package is sealed with
2193 * respect to the given code source {@link java.net.URL URL}
2194 * object. Otherwise, the package is not sealed.
2195 *
2196 * @return The newly defined {@code Package} object
2197 *
2198 * @throws NullPointerException
2199 * if {@code name} is {@code null}.
2200 *
2201 * @throws IllegalArgumentException
2202 * if a package of the given {@code name} is already
2203 * defined by this class loader
2204 *
2205 *
2206 * @since 1.2
2207 *
2208 * @jvms 5.3 Creation and Loading
2209 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
2210 * The JAR File Specification: Package Sealing</a>
2211 */
2212 protected Package definePackage(String name, String specTitle,
2213 String specVersion, String specVendor,
2214 String implTitle, String implVersion,
2215 String implVendor, URL sealBase)
2216 {
2217 Objects.requireNonNull(name);
2218
2219 // definePackage is not final and may be overridden by custom class loader
2220 Package p = new Package(name, specTitle, specVersion, specVendor,
2221 implTitle, implVersion, implVendor,
2222 sealBase, this);
2223
2224 if (packages.putIfAbsent(name, p) != null)
2225 throw new IllegalArgumentException(name);
2226
2227 return p;
2228 }
2229
2230 /**
2231 * Returns a {@code Package} of the given <a href="#binary-name">name</a> that
2232 * has been defined by this class loader.
2233 *
2234 * @param name The <a href="#binary-name">package name</a>
2235 *
2236 * @return The {@code Package} of the given name that has been defined
2237 * by this class loader, or {@code null} if not found
2238 *
2239 * @throws NullPointerException
2240 * if {@code name} is {@code null}.
2241 *
2242 * @jvms 5.3 Creation and Loading
2243 *
2244 * @since 9
2245 */
2246 public final Package getDefinedPackage(String name) {
2247 Objects.requireNonNull(name, "name cannot be null");
2248
2249 NamedPackage p = packages.get(name);
2250 if (p == null)
2251 return null;
2252
2253 return definePackage(name, p.module());
2254 }
2255
2256 /**
2257 * Returns all of the {@code Package}s that have been defined by
2258 * this class loader. The returned array has no duplicated {@code Package}s
2259 * of the same name.
2260 *
2261 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
2262 * for consistency with the existing {@link #getPackages} method.
2263 *
2264 * @return The array of {@code Package} objects that have been defined by
2265 * this class loader; or a zero length array if no package has been
2266 * defined by this class loader.
2267 *
2268 * @jvms 5.3 Creation and Loading
2269 *
2270 * @since 9
2271 */
2272 public final Package[] getDefinedPackages() {
2273 return packages().toArray(Package[]::new);
2274 }
2275
2276 /**
2277 * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors.
2278 * <p>
2279 * If this class loader defines a {@code Package} of the given name,
2280 * the {@code Package} is returned. Otherwise, the ancestors of
2281 * this class loader are searched recursively (parent by parent)
2282 * for a {@code Package} of the given name.
2283 *
2284 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2285 * may delegate to the application class loader but the application class
2286 * loader is not its ancestor. When invoked on the platform class loader,
2287 * this method will not find packages defined to the application
2288 * class loader.
2289 *
2290 * @param name
2291 * The <a href="#binary-name">package name</a>
2292 *
2293 * @return The {@code Package} of the given name that has been defined by
2294 * this class loader or its ancestors, or {@code null} if not found.
2295 *
2296 * @throws NullPointerException
2297 * if {@code name} is {@code null}.
2298 *
2299 * @deprecated
2300 * If multiple class loaders delegate to each other and define classes
2301 * with the same package name, and one such loader relies on the lookup
2302 * behavior of {@code getPackage} to return a {@code Package} from
2303 * a parent loader, then the properties exposed by the {@code Package}
2304 * may not be as expected in the rest of the program.
2305 * For example, the {@code Package} will only expose annotations from the
2306 * {@code package-info.class} file defined by the parent loader, even if
2307 * annotations exist in a {@code package-info.class} file defined by
2308 * a child loader. A more robust approach is to use the
2309 * {@link ClassLoader#getDefinedPackage} method which returns
2310 * a {@code Package} for the specified class loader.
2311 *
2312 * @see ClassLoader#getDefinedPackage(String)
2313 *
2314 * @since 1.2
2315 */
2316 @Deprecated(since="9")
2317 protected Package getPackage(String name) {
2318 Package pkg = getDefinedPackage(name);
2319 if (pkg == null) {
2320 if (parent != null) {
2321 pkg = parent.getPackage(name);
2322 } else {
2323 pkg = BootLoader.getDefinedPackage(name);
2324 }
2325 }
2326 return pkg;
2327 }
2328
2329 /**
2330 * Returns all of the {@code Package}s that have been defined by
2331 * this class loader and its ancestors. The returned array may contain
2332 * more than one {@code Package} object of the same package name, each
2333 * defined by a different class loader in the class loader hierarchy.
2334 *
2335 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2336 * may delegate to the application class loader. In other words,
2337 * packages in modules defined to the application class loader may be
2338 * visible to the platform class loader. On the other hand,
2339 * the application class loader is not its ancestor and hence
2340 * when invoked on the platform class loader, this method will not
2341 * return any packages defined to the application class loader.
2342 *
2343 * @return The array of {@code Package} objects that have been defined by
2344 * this class loader and its ancestors
2345 *
2346 * @see ClassLoader#getDefinedPackages()
2347 *
2348 * @since 1.2
2349 */
2350 protected Package[] getPackages() {
2351 Stream<Package> pkgs = packages();
2352 ClassLoader ld = parent;
2353 while (ld != null) {
2354 pkgs = Stream.concat(ld.packages(), pkgs);
2355 ld = ld.parent;
2356 }
2357 return Stream.concat(BootLoader.packages(), pkgs)
2358 .toArray(Package[]::new);
2359 }
2360
2361
2362
2363 // package-private
2364
2365 /**
2366 * Returns a stream of Packages defined in this class loader
2367 */
2368 Stream<Package> packages() {
2369 return packages.values().stream()
2370 .map(p -> definePackage(p.packageName(), p.module()));
2371 }
2372
2373 // -- Native library access --
2374
2375 /**
2376 * Returns the absolute path name of a native library. The VM invokes this
2377 * method to locate the native libraries that belong to classes loaded with
2378 * this class loader. If this method returns {@code null}, the VM
2379 * searches the library along the path specified as the
2380 * "{@code java.library.path}" property.
2381 *
2382 * @param libname
2383 * The library name
2384 *
2385 * @return The absolute path of the native library
2386 *
2387 * @see System#loadLibrary(String)
2388 * @see System#mapLibraryName(String)
2389 *
2390 * @since 1.2
2391 */
2392 protected String findLibrary(String libname) {
2393 return null;
2394 }
2395
2396 private final NativeLibraries libraries = NativeLibraries.newInstance(this);
2397
2398 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
2399 static NativeLibrary loadLibrary(Class<?> fromClass, File file) {
2400 ClassLoader loader = (fromClass == null) ? null : fromClass.getClassLoader();
2401 NativeLibraries libs = loader != null ? loader.libraries : BootLoader.getNativeLibraries();
2402 NativeLibrary nl = libs.loadLibrary(fromClass, file);
2403 if (nl != null) {
2404 return nl;
2405 }
2406 throw new UnsatisfiedLinkError("Can't load library: " + file);
2407 }
2408 static NativeLibrary loadLibrary(Class<?> fromClass, String name) {
2409 ClassLoader loader = (fromClass == null) ? null : fromClass.getClassLoader();
2410 if (loader == null) {
2411 NativeLibrary nl = BootLoader.getNativeLibraries().loadLibrary(fromClass, name);
2412 if (nl != null) {
2413 return nl;
2414 }
2415 throw new UnsatisfiedLinkError("no " + name +
2416 " in system library path: " + StaticProperty.sunBootLibraryPath());
2417 }
2418
2419 NativeLibraries libs = loader.libraries;
2420 // First load from the file returned from ClassLoader::findLibrary, if found.
2421 String libfilename = loader.findLibrary(name);
2422 if (libfilename != null) {
2423 File libfile = new File(libfilename);
2424 if (!libfile.isAbsolute()) {
2425 throw new UnsatisfiedLinkError(
2426 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
2427 }
2428 NativeLibrary nl = libs.loadLibrary(fromClass, libfile);
2429 if (nl != null) {
2430 return nl;
2431 }
2432 throw new UnsatisfiedLinkError("Can't load " + libfilename);
2433 }
2434 // Then load from system library path and java library path
2435 NativeLibrary nl = libs.loadLibrary(fromClass, name);
2436 if (nl != null) {
2437 return nl;
2438 }
2439
2440 // Oops, it failed
2441 throw new UnsatisfiedLinkError("no " + name +
2442 " in java.library.path: " + StaticProperty.javaLibraryPath());
2443 }
2444
2445 /*
2446 * Invoked in the VM class linking code.
2447 */
2448 static long findNative(ClassLoader loader, String entryName) {
2449 if (loader == null) {
2450 return BootLoader.getNativeLibraries().find(entryName);
2451 } else {
2452 return loader.libraries.find(entryName);
2453 }
2454 }
2455
2456 // -- Assertion management --
2457
2458 final Object assertionLock;
2459
2460 // The default toggle for assertion checking.
2461 // @GuardedBy("assertionLock")
2462 private boolean defaultAssertionStatus = false;
2463
2464 // Maps String packageName to Boolean package default assertion status Note
2465 // that the default package is placed under a null map key. If this field
2466 // is null then we are delegating assertion status queries to the VM, i.e.,
2467 // none of this ClassLoader's assertion status modification methods have
2468 // been invoked.
2469 // @GuardedBy("assertionLock")
2470 private Map<String, Boolean> packageAssertionStatus = null;
2471
2472 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
2473 // field is null then we are delegating assertion status queries to the VM,
2474 // i.e., none of this ClassLoader's assertion status modification methods
2475 // have been invoked.
2476 // @GuardedBy("assertionLock")
2477 Map<String, Boolean> classAssertionStatus = null;
2478
2479 /**
2480 * Sets the default assertion status for this class loader. This setting
2481 * determines whether classes loaded by this class loader and initialized
2482 * in the future will have assertions enabled or disabled by default.
2483 * This setting may be overridden on a per-package or per-class basis by
2484 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
2485 * #setClassAssertionStatus(String, boolean)}.
2486 *
2487 * @param enabled
2488 * {@code true} if classes loaded by this class loader will
2489 * henceforth have assertions enabled by default, {@code false}
2490 * if they will have assertions disabled by default.
2491 *
2492 * @since 1.4
2493 */
2494 public void setDefaultAssertionStatus(boolean enabled) {
2495 synchronized (assertionLock) {
2496 if (classAssertionStatus == null)
2497 initializeJavaAssertionMaps();
2498
2499 defaultAssertionStatus = enabled;
2500 }
2501 }
2502
2503 /**
2504 * Sets the package default assertion status for the named package. The
2505 * package default assertion status determines the assertion status for
2506 * classes initialized in the future that belong to the named package or
2507 * any of its "subpackages".
2508 *
2509 * <p> A subpackage of a package named p is any package whose name begins
2510 * with "{@code p.}". For example, {@code javax.swing.text} is a
2511 * subpackage of {@code javax.swing}, and both {@code java.util} and
2512 * {@code java.lang.reflect} are subpackages of {@code java}.
2513 *
2514 * <p> In the event that multiple package defaults apply to a given class,
2515 * the package default pertaining to the most specific package takes
2516 * precedence over the others. For example, if {@code javax.lang} and
2517 * {@code javax.lang.reflect} both have package defaults associated with
2518 * them, the latter package default applies to classes in
2519 * {@code javax.lang.reflect}.
2520 *
2521 * <p> Package defaults take precedence over the class loader's default
2522 * assertion status, and may be overridden on a per-class basis by invoking
2523 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2524 *
2525 * @param packageName
2526 * The name of the package whose package default assertion status
2527 * is to be set. A {@code null} value indicates the unnamed
2528 * package that is "current"
2529 * (see section {@jls 7.4.2} of
2530 * <cite>The Java Language Specification</cite>.)
2531 *
2532 * @param enabled
2533 * {@code true} if classes loaded by this classloader and
2534 * belonging to the named package or any of its subpackages will
2535 * have assertions enabled by default, {@code false} if they will
2536 * have assertions disabled by default.
2537 *
2538 * @since 1.4
2539 */
2540 public void setPackageAssertionStatus(String packageName,
2541 boolean enabled) {
2542 synchronized (assertionLock) {
2543 if (packageAssertionStatus == null)
2544 initializeJavaAssertionMaps();
2545
2546 packageAssertionStatus.put(packageName, enabled);
2547 }
2548 }
2549
2550 /**
2551 * Sets the desired assertion status for the named top-level class in this
2552 * class loader and any nested classes contained therein. This setting
2553 * takes precedence over the class loader's default assertion status, and
2554 * over any applicable per-package default. This method has no effect if
2555 * the named class has already been initialized. (Once a class is
2556 * initialized, its assertion status cannot change.)
2557 *
2558 * <p> If the named class is not a top-level class, this invocation will
2559 * have no effect on the actual assertion status of any class. </p>
2560 *
2561 * @param className
2562 * The fully qualified class name of the top-level class whose
2563 * assertion status is to be set.
2564 *
2565 * @param enabled
2566 * {@code true} if the named class is to have assertions
2567 * enabled when (and if) it is initialized, {@code false} if the
2568 * class is to have assertions disabled.
2569 *
2570 * @since 1.4
2571 */
2572 public void setClassAssertionStatus(String className, boolean enabled) {
2573 synchronized (assertionLock) {
2574 if (classAssertionStatus == null)
2575 initializeJavaAssertionMaps();
2576
2577 classAssertionStatus.put(className, enabled);
2578 }
2579 }
2580
2581 /**
2582 * Sets the default assertion status for this class loader to
2583 * {@code false} and discards any package defaults or class assertion
2584 * status settings associated with the class loader. This method is
2585 * provided so that class loaders can be made to ignore any command line or
2586 * persistent assertion status settings and "start with a clean slate."
2587 *
2588 * @since 1.4
2589 */
2590 public void clearAssertionStatus() {
2591 /*
2592 * Whether or not "Java assertion maps" are initialized, set
2593 * them to empty maps, effectively ignoring any present settings.
2594 */
2595 synchronized (assertionLock) {
2596 classAssertionStatus = new HashMap<>();
2597 packageAssertionStatus = new HashMap<>();
2598 defaultAssertionStatus = false;
2599 }
2600 }
2601
2602 /**
2603 * Returns the assertion status that would be assigned to the specified
2604 * class if it were to be initialized at the time this method is invoked.
2605 * If the named class has had its assertion status set, the most recent
2606 * setting will be returned; otherwise, if any package default assertion
2607 * status pertains to this class, the most recent setting for the most
2608 * specific pertinent package default assertion status is returned;
2609 * otherwise, this class loader's default assertion status is returned.
2610 * </p>
2611 *
2612 * @param className
2613 * The fully qualified class name of the class whose desired
2614 * assertion status is being queried.
2615 *
2616 * @return The desired assertion status of the specified class.
2617 *
2618 * @see #setClassAssertionStatus(String, boolean)
2619 * @see #setPackageAssertionStatus(String, boolean)
2620 * @see #setDefaultAssertionStatus(boolean)
2621 *
2622 * @since 1.4
2623 */
2624 boolean desiredAssertionStatus(String className) {
2625 synchronized (assertionLock) {
2626 // assert classAssertionStatus != null;
2627 // assert packageAssertionStatus != null;
2628
2629 // Check for a class entry
2630 Boolean result = classAssertionStatus.get(className);
2631 if (result != null)
2632 return result.booleanValue();
2633
2634 // Check for most specific package entry
2635 int dotIndex = className.lastIndexOf('.');
2636 if (dotIndex < 0) { // default package
2637 result = packageAssertionStatus.get(null);
2638 if (result != null)
2639 return result.booleanValue();
2640 }
2641 while(dotIndex > 0) {
2642 className = className.substring(0, dotIndex);
2643 result = packageAssertionStatus.get(className);
2644 if (result != null)
2645 return result.booleanValue();
2646 dotIndex = className.lastIndexOf('.', dotIndex-1);
2647 }
2648
2649 // Return the classloader default
2650 return defaultAssertionStatus;
2651 }
2652 }
2653
2654 // Set up the assertions with information provided by the VM.
2655 // Note: Should only be called inside a synchronized block
2656 private void initializeJavaAssertionMaps() {
2657 // assert Thread.holdsLock(assertionLock);
2658
2659 classAssertionStatus = new HashMap<>();
2660 packageAssertionStatus = new HashMap<>();
2661 AssertionStatusDirectives directives = retrieveDirectives();
2662
2663 for(int i = 0; i < directives.classes.length; i++)
2664 classAssertionStatus.put(directives.classes[i],
2665 directives.classEnabled[i]);
2666
2667 for(int i = 0; i < directives.packages.length; i++)
2668 packageAssertionStatus.put(directives.packages[i],
2669 directives.packageEnabled[i]);
2670
2671 defaultAssertionStatus = directives.deflt;
2672 }
2673
2674 // Retrieves the assertion directives from the VM.
2675 private static native AssertionStatusDirectives retrieveDirectives();
2676
2677
2678 // -- Misc --
2679
2680 /**
2681 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
2682 * associated with this ClassLoader, creating it if it doesn't already exist.
2683 */
2684 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
2685 ConcurrentHashMap<?, ?> map = classLoaderValueMap;
2686 if (map == null) {
2687 map = new ConcurrentHashMap<>();
2688 boolean set = trySetObjectField("classLoaderValueMap", map);
2689 if (!set) {
2690 // beaten by someone else
2691 map = classLoaderValueMap;
2692 }
2693 }
2694 return map;
2695 }
2696
2697 // the storage for ClassLoaderValue(s) associated with this ClassLoader
2698 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
2699
2700 /**
2701 * Attempts to atomically set a volatile field in this object. Returns
2702 * {@code true} if not beaten by another thread. Avoids the use of
2703 * AtomicReferenceFieldUpdater in this class.
2704 */
2705 private boolean trySetObjectField(String name, Object obj) {
2706 Unsafe unsafe = Unsafe.getUnsafe();
2707 Class<?> k = ClassLoader.class;
2708 long offset;
2709 offset = unsafe.objectFieldOffset(k, name);
2710 return unsafe.compareAndSetReference(this, offset, null, obj);
2711 }
2712
2713 /**
2714 * Called by the VM, during -Xshare:dump
2715 */
2716 private void resetArchivedStates() {
2717 if (parallelLockMap != null) {
2718 parallelLockMap.clear();
2719 }
2720 packages.clear();
2721 package2certs.clear();
2722 classes.clear();
2723 classLoaderValueMap = null;
2724 }
2725 }
2726
2727 /*
2728 * A utility class that will enumerate over an array of enumerations.
2729 */
2730 final class CompoundEnumeration<E> implements Enumeration<E> {
2731 private final Enumeration<E>[] enums;
2732 private int index;
2733
2734 public CompoundEnumeration(Enumeration<E>[] enums) {
2735 this.enums = enums;
2736 }
2737
2738 private boolean next() {
2739 while (index < enums.length) {
2740 if (enums[index] != null && enums[index].hasMoreElements()) {
2741 return true;
2742 }
2743 index++;
2744 }
2745 return false;
2746 }
2747
2748 public boolean hasMoreElements() {
2749 return next();
2750 }
2751
2752 public E nextElement() {
2753 if (!next()) {
2754 throw new NoSuchElementException();
2755 }
2756 return enums[index].nextElement();
2757 }
2758 }