1 /*
2 * Copyright (c) 2013, 2024, 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.CDS;
65 import jdk.internal.misc.Unsafe;
66 import jdk.internal.misc.VM;
67 import jdk.internal.reflect.CallerSensitive;
68 import jdk.internal.reflect.CallerSensitiveAdapter;
69 import jdk.internal.reflect.Reflection;
70 import jdk.internal.util.StaticProperty;
71 import sun.reflect.misc.ReflectUtil;
72 import sun.security.util.SecurityConstants;
73
74 /**
75 * A class loader is an object that is responsible for loading classes. The
76 * class {@code ClassLoader} is an abstract class. Given the <a
77 * href="#binary-name">binary name</a> of a class, a class loader should attempt to
78 * locate or generate data that constitutes a definition for the class. A
79 * typical strategy is to transform the name into a file name and then read a
80 * "class file" of that name from a file system.
81 *
82 * <p> Every {@link java.lang.Class Class} object contains a {@link
83 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
84 * it.
85 *
86 * <p> {@code Class} objects for array classes are not created by class
87 * loaders, but are created automatically as required by the Java runtime.
88 * The class loader for an array class, as returned by {@link
89 * Class#getClassLoader()} is the same as the class loader for its element
90 * type; if the element type is a primitive type, then the array class has no
91 * class loader.
92 *
93 * <p> Applications implement subclasses of {@code ClassLoader} in order to
94 * extend the manner in which the Java virtual machine dynamically loads
95 * classes.
96 *
97 * <p> Class loaders may typically be used by security managers to indicate
98 * security domains.
99 *
100 * <p> In addition to loading classes, a class loader is also responsible for
101 * locating resources. A resource is some data (a "{@code .class}" file,
102 * configuration data, or an image for example) that is identified with an
103 * abstract '/'-separated path name. Resources are typically packaged with an
104 * application or library so that they can be located by code in the
105 * application or library. In some cases, the resources are included so that
106 * they can be located by other libraries.
107 *
108 * <p> The {@code ClassLoader} class uses a delegation model to search for
109 * classes and resources. Each instance of {@code ClassLoader} has an
110 * associated parent class loader. When requested to find a class or
111 * resource, a {@code ClassLoader} instance will usually delegate the search
112 * for the class or resource to its parent class loader before attempting to
113 * find the class or resource itself.
114 *
115 * <p> Class loaders that support concurrent loading of classes are known as
116 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
117 * loaders and are required to register themselves at their class initialization
118 * time by invoking the {@link
119 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
120 * method. Note that the {@code ClassLoader} class is registered as parallel
121 * capable by default. However, its subclasses still need to register themselves
122 * if they are parallel capable.
123 * In environments in which the delegation model is not strictly
124 * hierarchical, class loaders need to be parallel capable, otherwise class
125 * loading can lead to deadlocks because the loader lock is held for the
126 * duration of the class loading process (see {@link #loadClass
127 * loadClass} methods).
128 *
129 * <h2> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h2>
130 *
131 * The Java run-time has the following built-in class loaders:
132 *
133 * <ul>
134 * <li><p>Bootstrap class loader.
135 * It is the virtual machine's built-in class loader, typically represented
136 * as {@code null}, and does not have a parent.</li>
137 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
138 * The platform class loader is responsible for loading the
139 * <em>platform classes</em>. Platform classes include Java SE platform APIs,
140 * their implementation classes and JDK-specific run-time classes that are
141 * defined by the platform class loader or its ancestors.
142 * The platform class loader can be used as the parent of a {@code ClassLoader}
143 * instance.
144 * <p> To allow for upgrading/overriding of modules defined to the platform
145 * class loader, and where upgraded modules read modules defined to class
146 * loaders other than the platform class loader and its ancestors, then
147 * the platform class loader may have to delegate to other class loaders,
148 * the application class loader for example.
149 * In other words, classes in named modules defined to class loaders
150 * other than the platform class loader and its ancestors may be visible
151 * to the platform class loader. </li>
152 * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
153 * It is also known as <em>application class loader</em> and is distinct
154 * from the platform class loader.
155 * The system class loader is typically used to define classes on the
156 * application class path, module path, and JDK-specific tools.
157 * The platform class loader is the parent or an ancestor of the system class
158 * loader, so the system class loader can load platform classes by delegating
159 * to its parent.</li>
160 * </ul>
161 *
162 * <p> Normally, the Java virtual machine loads classes from the local file
163 * system in a platform-dependent manner.
164 * However, some classes may not originate from a file; they may originate
165 * from other sources, such as the network, or they could be constructed by an
166 * application. The method {@link #defineClass(String, byte[], int, int)
167 * defineClass} converts an array of bytes into an instance of class
168 * {@code Class}. Instances of this newly defined class can be created using
169 * {@link Class#newInstance Class.newInstance}.
170 *
171 * <p> The methods and constructors of objects created by a class loader may
172 * reference other classes. To determine the class(es) referred to, the Java
173 * virtual machine invokes the {@link #loadClass loadClass} method of
174 * the class loader that originally created the class.
175 *
176 * <p> For example, an application could create a network class loader to
177 * download class files from a server. Sample code might look like:
178 *
179 * <blockquote><pre>
180 * ClassLoader loader = new NetworkClassLoader(host, port);
181 * Object main = loader.loadClass("Main", true).newInstance();
182 * . . .
183 * </pre></blockquote>
184 *
185 * <p> The network class loader subclass must define the methods {@link
186 * #findClass findClass} and {@code loadClassData} to load a class
187 * from the network. Once it has downloaded the bytes that make up the class,
188 * it should use the method {@link #defineClass defineClass} to
189 * create a class instance. A sample implementation is:
190 *
191 * <blockquote><pre>
192 * class NetworkClassLoader extends ClassLoader {
193 * String host;
194 * int port;
195 *
196 * public Class findClass(String name) {
197 * byte[] b = loadClassData(name);
198 * return defineClass(name, b, 0, b.length);
199 * }
200 *
201 * private byte[] loadClassData(String name) {
202 * // load the class data from the connection
203 * . . .
204 * }
205 * }
206 * </pre></blockquote>
207 *
208 * <h3> <a id="binary-name">Binary names</a> </h3>
209 *
210 * <p> Any class name provided as a {@code String} parameter to methods in
211 * {@code ClassLoader} must be a binary name as defined by
212 * <cite>The Java Language Specification</cite>.
213 *
214 * <p> Examples of valid class names include:
215 * <blockquote><pre>
216 * "java.lang.String"
217 * "javax.swing.JSpinner$DefaultEditor"
218 * "java.security.KeyStore$Builder$FileBuilder$1"
219 * "java.net.URLClassLoader$3$1"
220 * </pre></blockquote>
221 *
222 * <p> Any package name provided as a {@code String} parameter to methods in
223 * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
224 * or a fully qualified name as defined by
225 * <cite>The Java Language Specification</cite>.
226 *
227 * @jls 6.7 Fully Qualified Names and Canonical Names
228 * @jls 13.1 The Form of a Binary
229 * @see #resolveClass(Class)
230 * @since 1.0
231 */
232 public abstract class ClassLoader {
233
234 private static native void registerNatives();
235 static {
236 registerNatives();
237 }
238
239 // The parent class loader for delegation
240 // Note: VM hardcoded the offset of this field, thus all new fields
241 // must be added *after* it.
242 private final ClassLoader parent;
243
244 // class loader name
245 private final String name;
246
247 // the unnamed module for this ClassLoader
248 private final Module unnamedModule;
249
250 // a string for exception message printing
251 private final String nameAndId;
252
253 /**
254 * Encapsulates the set of parallel capable loader types.
255 */
256 private static class ParallelLoaders {
257 private ParallelLoaders() {}
258
259 // the set of parallel capable loader types
260 private static final Set<Class<? extends ClassLoader>> loaderTypes =
261 Collections.newSetFromMap(new WeakHashMap<>());
262 static {
263 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
264 }
265
266 /**
267 * Registers the given class loader type as parallel capable.
268 * Returns {@code true} is successfully registered; {@code false} if
269 * loader's super class is not registered.
270 */
271 static boolean register(Class<? extends ClassLoader> c) {
272 synchronized (loaderTypes) {
273 if (loaderTypes.contains(c.getSuperclass())) {
274 // register the class loader as parallel capable
275 // if and only if all of its super classes are.
276 // Note: given current classloading sequence, if
277 // the immediate super class is parallel capable,
278 // all the super classes higher up must be too.
279 loaderTypes.add(c);
280 return true;
281 } else {
282 return false;
283 }
284 }
285 }
286
287 /**
288 * Returns {@code true} if the given class loader type is
289 * registered as parallel capable.
290 */
291 static boolean isRegistered(Class<? extends ClassLoader> c) {
292 synchronized (loaderTypes) {
293 return loaderTypes.contains(c);
294 }
295 }
296 }
297
298 // Maps class name to the corresponding lock object when the current
299 // class loader is parallel capable.
300 // Note: VM also uses this field to decide if the current class loader
301 // is parallel capable and the appropriate lock object for class loading.
302 private final ConcurrentHashMap<String, Object> parallelLockMap;
303
304 // Maps packages to certs
305 private final ConcurrentHashMap<String, Certificate[]> package2certs;
306
307 // Shared among all packages with unsigned classes
308 private static final Certificate[] nocerts = new Certificate[0];
309
310 // The classes loaded by this class loader. The only purpose of this table
311 // is to keep the classes from being GC'ed until the loader is GC'ed.
312 private final ArrayList<Class<?>> classes = new ArrayList<>();
313
314 // The "default" domain. Set as the default ProtectionDomain on newly
315 // created classes.
316 private final ProtectionDomain defaultDomain =
317 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
318 null, this, null);
319
320 // Invoked by the VM to record every loaded class with this loader.
321 void addClass(Class<?> c) {
322 synchronized (classes) {
323 classes.add(c);
324 }
325 }
326
327 // The packages defined in this class loader. Each package name is
328 // mapped to its corresponding NamedPackage object.
329 //
330 // The value is a Package object if ClassLoader::definePackage,
331 // Class::getPackage, ClassLoader::getDefinePackage(s) or
332 // Package::getPackage(s) method is called to define it.
333 // Otherwise, the value is a NamedPackage object.
334 private final ConcurrentHashMap<String, NamedPackage> packages
335 = new ConcurrentHashMap<>();
336
337 /*
338 * Returns a named package for the given module.
339 */
340 private NamedPackage getNamedPackage(String pn, Module m) {
341 NamedPackage p = packages.get(pn);
342 if (p == null) {
343 p = new NamedPackage(pn, m);
344
345 NamedPackage value = packages.putIfAbsent(pn, p);
346 if (value != null) {
347 // Package object already be defined for the named package
348 p = value;
349 // if definePackage is called by this class loader to define
350 // a package in a named module, this will return Package
351 // object of the same name. Package object may contain
352 // unexpected information but it does not impact the runtime.
353 // this assertion may be helpful for troubleshooting
354 assert value.module() == m;
355 }
356 }
357 return p;
358 }
359
360 private static Void checkCreateClassLoader() {
361 return checkCreateClassLoader(null);
362 }
363
364 private static Void checkCreateClassLoader(String name) {
365 if (name != null && name.isEmpty()) {
366 throw new IllegalArgumentException("name must be non-empty or null");
367 }
368
369 @SuppressWarnings("removal")
370 SecurityManager security = System.getSecurityManager();
371 if (security != null) {
372 security.checkCreateClassLoader();
373 }
374 return null;
375 }
376
377 private ClassLoader(Void unused, String name, ClassLoader parent) {
378 this.name = name;
379 this.parent = parent;
380 this.unnamedModule = new Module(this);
381 if (ParallelLoaders.isRegistered(this.getClass())) {
382 parallelLockMap = new ConcurrentHashMap<>();
383 assertionLock = new Object();
384 } else {
385 // no finer-grained lock; lock on the classloader instance
386 parallelLockMap = null;
387 assertionLock = this;
388 }
389 this.package2certs = new ConcurrentHashMap<>();
390 this.nameAndId = nameAndId(this);
391 }
392
393 /**
394 * If the defining loader has a name explicitly set then
395 * '<loader-name>' @<id>
396 * If the defining loader has no name then
397 * <qualified-class-name> @<id>
398 * If it's built-in loader then omit `@<id>` as there is only one instance.
399 */
400 private static String nameAndId(ClassLoader ld) {
401 String nid = ld.getName() != null ? "\'" + ld.getName() + "\'"
402 : ld.getClass().getName();
403 if (!(ld instanceof BuiltinClassLoader)) {
404 String id = Integer.toHexString(System.identityHashCode(ld));
405 nid = nid + " @" + id;
406 }
407 return nid;
408 }
409
410 // Returns nameAndId string for exception message printing
411 String nameAndId() {
412 return nameAndId;
413 }
414
415 /**
416 * Creates a new class loader of the specified name and using the
417 * specified parent class loader for delegation.
418 *
419 * @apiNote If the parent is specified as {@code null} (for the
420 * bootstrap class loader) then there is no guarantee that all platform
421 * classes are visible.
422 *
423 * @param name class loader name; or {@code null} if not named
424 * @param parent the parent class loader
425 *
426 * @throws IllegalArgumentException if the given name is empty.
427 *
428 * @throws SecurityException
429 * If a security manager exists and its
430 * {@link SecurityManager#checkCreateClassLoader()}
431 * method doesn't allow creation of a new class loader.
432 *
433 * @since 9
434 */
435 @SuppressWarnings("this-escape")
436 protected ClassLoader(String name, ClassLoader parent) {
437 this(checkCreateClassLoader(name), name, parent);
438 }
439
440 /**
441 * Creates a new class loader using the specified parent class loader for
442 * delegation.
443 *
444 * <p> If there is a security manager, its {@link
445 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
446 * is invoked. This may result in a security exception. </p>
447 *
448 * @apiNote If the parent is specified as {@code null} (for the
449 * bootstrap class loader) then there is no guarantee that all platform
450 * classes are visible.
451 *
452 * @param parent
453 * The parent class loader
454 *
455 * @throws SecurityException
456 * If a security manager exists and its
457 * {@code checkCreateClassLoader} method doesn't allow creation
458 * of a new class loader.
459 *
460 * @since 1.2
461 */
462 @SuppressWarnings("this-escape")
463 protected ClassLoader(ClassLoader parent) {
464 this(checkCreateClassLoader(), null, parent);
465 }
466
467 /**
468 * Creates a new class loader using the {@code ClassLoader} returned by
469 * the method {@link #getSystemClassLoader()
470 * getSystemClassLoader()} as the parent class loader.
471 *
472 * <p> If there is a security manager, its {@link
473 * SecurityManager#checkCreateClassLoader()
474 * checkCreateClassLoader} method is invoked. This may result in
475 * a security exception. </p>
476 *
477 * @throws SecurityException
478 * If a security manager exists and its
479 * {@code checkCreateClassLoader} method doesn't allow creation
480 * of a new class loader.
481 */
482 @SuppressWarnings("this-escape")
483 protected ClassLoader() {
484 this(checkCreateClassLoader(), null, getSystemClassLoader());
485 }
486
487 /**
488 * Returns the name of this class loader or {@code null} if
489 * this class loader is not named.
490 *
491 * @apiNote This method is non-final for compatibility. If this
492 * method is overridden, this method must return the same name
493 * as specified when this class loader was instantiated.
494 *
495 * @return name of this class loader; or {@code null} if
496 * this class loader is not named.
497 *
498 * @since 9
499 */
500 public String getName() {
501 return name;
502 }
503
504 // package-private used by StackTraceElement to avoid
505 // calling the overridable getName method
506 final String name() {
507 return name;
508 }
509
510 // -- Class --
511
512 /**
513 * Loads the class with the specified <a href="#binary-name">binary name</a>.
514 * This method searches for classes in the same manner as the {@link
515 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
516 * machine to resolve class references. Invoking this method is equivalent
517 * to invoking {@link #loadClass(String, boolean) loadClass(name,
518 * false)}.
519 *
520 * @param name
521 * The <a href="#binary-name">binary name</a> of the class
522 *
523 * @return The resulting {@code Class} object
524 *
525 * @throws ClassNotFoundException
526 * If the class was not found
527 */
528 public Class<?> loadClass(String name) throws ClassNotFoundException {
529 return loadClass(name, false);
530 }
531
532 /**
533 * Loads the class with the specified <a href="#binary-name">binary name</a>. The
534 * default implementation of this method searches for classes in the
535 * following order:
536 *
537 * <ol>
538 *
539 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
540 * has already been loaded. </p></li>
541 *
542 * <li><p> Invoke the {@link #loadClass(String) loadClass} method
543 * on the parent class loader. If the parent is {@code null} the class
544 * loader built into the virtual machine is used, instead. </p></li>
545 *
546 * <li><p> Invoke the {@link #findClass(String)} method to find the
547 * class. </p></li>
548 *
549 * </ol>
550 *
551 * <p> If the class was found using the above steps, and the
552 * {@code resolve} flag is true, this method will then invoke the {@link
553 * #resolveClass(Class)} method on the resulting {@code Class} object.
554 *
555 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
556 * #findClass(String)}, rather than this method. </p>
557 *
558 * <p> Unless overridden, this method synchronizes on the result of
559 * {@link #getClassLoadingLock getClassLoadingLock} method
560 * during the entire class loading process.
561 *
562 * @param name
563 * The <a href="#binary-name">binary name</a> of the class
564 *
565 * @param resolve
566 * If {@code true} then resolve the class
567 *
568 * @return The resulting {@code Class} object
569 *
570 * @throws ClassNotFoundException
571 * If the class could not be found
572 */
573 protected Class<?> loadClass(String name, boolean resolve)
574 throws ClassNotFoundException
575 {
576 synchronized (getClassLoadingLock(name)) {
577 // First, check if the class has already been loaded
578 Class<?> c = findLoadedClass(name);
579 if (c == null) {
580 long t0 = System.nanoTime();
581 try {
582 if (parent != null) {
583 c = parent.loadClass(name, false);
584 } else {
585 c = findBootstrapClassOrNull(name);
586 }
587 } catch (ClassNotFoundException e) {
588 // ClassNotFoundException thrown if class not found
589 // from the non-null parent class loader
590 }
591
592 if (c == null) {
593 // If still not found, then invoke findClass in order
594 // to find the class.
595 long t1 = System.nanoTime();
596 c = findClass(name);
597
598 // this is the defining class loader; record the stats
599 PerfCounter.getParentDelegationTime().addTime(t1 - t0);
600 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
601 PerfCounter.getFindClasses().increment();
602 }
603 }
604 if (resolve) {
605 resolveClass(c);
606 }
607 return c;
608 }
609 }
610
611 /**
612 * Loads the class with the specified <a href="#binary-name">binary name</a>
613 * in a module defined to this class loader. This method returns {@code null}
614 * if the class could not be found.
615 *
616 * @apiNote This method does not delegate to the parent class loader.
617 *
618 * @implSpec The default implementation of this method searches for classes
619 * in the following order:
620 *
621 * <ol>
622 * <li>Invoke {@link #findLoadedClass(String)} to check if the class
623 * has already been loaded.</li>
624 * <li>Invoke the {@link #findClass(String, String)} method to find the
625 * class in the given module.</li>
626 * </ol>
627 *
628 * @param module
629 * The module
630 * @param name
631 * The <a href="#binary-name">binary name</a> of the class
632 *
633 * @return The resulting {@code Class} object in a module defined by
634 * this class loader, or {@code null} if the class could not be found.
635 */
636 final Class<?> loadClass(Module module, String name) {
637 synchronized (getClassLoadingLock(name)) {
638 // First, check if the class has already been loaded
639 Class<?> c = findLoadedClass(name);
640 if (c == null) {
641 c = findClass(module.getName(), name);
642 }
643 if (c != null && c.getModule() == module) {
644 return c;
645 } else {
646 return null;
647 }
648 }
649 }
650
651 /**
652 * Returns the lock object for class loading operations.
653 *
654 * @implSpec
655 * If this {@code ClassLoader} object is registered as parallel capable,
656 * this method returns a dedicated object associated with the specified
657 * class name. Otherwise, this method returns this {@code ClassLoader} object.
658 *
659 * @apiNote
660 * This method allows parallel capable class loaders to implement
661 * finer-grained locking schemes such that multiple threads may load classes
662 * concurrently without deadlocks. For non-parallel-capable class loaders,
663 * the {@code ClassLoader} object is synchronized on during the class loading
664 * operations. Class loaders with non-hierarchical delegation should be
665 * {@linkplain #registerAsParallelCapable() registered as parallel capable}
666 * to prevent deadlocks.
667 *
668 * @param className
669 * The name of the to-be-loaded class
670 *
671 * @return the lock for class loading operations
672 *
673 * @throws NullPointerException
674 * If registered as parallel capable and {@code className} is {@code null}
675 *
676 * @see #loadClass(String, boolean)
677 *
678 * @since 1.7
679 */
680 protected Object getClassLoadingLock(String className) {
681 Object lock = this;
682 if (parallelLockMap != null) {
683 Object newLock = new Object();
684 lock = parallelLockMap.putIfAbsent(className, newLock);
685 if (lock == null) {
686 lock = newLock;
687 }
688 }
689 return lock;
690 }
691
692 // Invoked by the VM after loading class with this loader.
693 @SuppressWarnings("removal")
694 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
695 final SecurityManager sm = System.getSecurityManager();
696 if (sm != null) {
697 if (ReflectUtil.isNonPublicProxyClass(cls)) {
698 for (Class<?> intf: cls.getInterfaces()) {
699 checkPackageAccess(intf, pd);
700 }
701 return;
702 }
703
704 final String packageName = cls.getPackageName();
705 if (!packageName.isEmpty()) {
706 AccessController.doPrivileged(new PrivilegedAction<>() {
707 public Void run() {
708 sm.checkPackageAccess(packageName);
709 return null;
710 }
711 }, new AccessControlContext(new ProtectionDomain[] {pd}));
712 }
713 }
714 }
715
716 /**
717 * Finds the class with the specified <a href="#binary-name">binary name</a>.
718 * This method should be overridden by class loader implementations that
719 * follow the delegation model for loading classes, and will be invoked by
720 * the {@link #loadClass loadClass} method after checking the
721 * parent class loader for the requested class.
722 *
723 * @implSpec The default implementation throws {@code ClassNotFoundException}.
724 *
725 * @param name
726 * The <a href="#binary-name">binary name</a> of the class
727 *
728 * @return The resulting {@code Class} object
729 *
730 * @throws ClassNotFoundException
731 * If the class could not be found
732 *
733 * @since 1.2
734 */
735 protected Class<?> findClass(String name) throws ClassNotFoundException {
736 throw new ClassNotFoundException(name);
737 }
738
739 /**
740 * Finds the class with the given <a href="#binary-name">binary name</a>
741 * in a module defined to this class loader.
742 * Class loader implementations that support loading from modules
743 * should override this method.
744 *
745 * @apiNote This method returns {@code null} rather than throwing
746 * {@code ClassNotFoundException} if the class could not be found.
747 *
748 * @implSpec The default implementation attempts to find the class by
749 * invoking {@link #findClass(String)} when the {@code moduleName} is
750 * {@code null}. It otherwise returns {@code null}.
751 *
752 * @param moduleName
753 * The module name; or {@code null} to find the class in the
754 * {@linkplain #getUnnamedModule() unnamed module} for this
755 * class loader
756 * @param name
757 * The <a href="#binary-name">binary name</a> of the class
758 *
759 * @return The resulting {@code Class} object, or {@code null}
760 * if the class could not be found.
761 *
762 * @since 9
763 */
764 protected Class<?> findClass(String moduleName, String name) {
765 if (moduleName == null) {
766 try {
767 return findClass(name);
768 } catch (ClassNotFoundException ignore) { }
769 }
770 return null;
771 }
772
773
774 /**
775 * Converts an array of bytes into an instance of class {@code Class}.
776 * Before the {@code Class} can be used it must be resolved. This method
777 * is deprecated in favor of the version that takes a <a
778 * href="#binary-name">binary name</a> as its first argument, and is more secure.
779 *
780 * @param b
781 * The bytes that make up the class data. The bytes in positions
782 * {@code off} through {@code off+len-1} should have the format
783 * of a valid class file as defined by
784 * <cite>The Java Virtual Machine Specification</cite>.
785 *
786 * @param off
787 * The start offset in {@code b} of the class data
788 *
789 * @param len
790 * The length of the class data
791 *
792 * @return The {@code Class} object that was created from the specified
793 * class data
794 *
795 * @throws ClassFormatError
796 * If the data did not contain a valid class
797 *
798 * @throws IndexOutOfBoundsException
799 * If either {@code off} or {@code len} is negative, or if
800 * {@code off+len} is greater than {@code b.length}.
801 *
802 * @throws SecurityException
803 * If an attempt is made to add this class to a package that
804 * contains classes that were signed by a different set of
805 * certificates than this class, or if an attempt is made
806 * to define a class in a package with a fully-qualified name
807 * that starts with "{@code java.}".
808 *
809 * @see #loadClass(String, boolean)
810 * @see #resolveClass(Class)
811 *
812 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
813 * defineClass(String, byte[], int, int)}
814 */
815 @Deprecated(since="1.1")
816 protected final Class<?> defineClass(byte[] b, int off, int len)
817 throws ClassFormatError
818 {
819 return defineClass(null, b, off, len, null);
820 }
821
822 /**
823 * Converts an array of bytes into an instance of class {@code Class}.
824 * Before the {@code Class} can be used it must be resolved.
825 *
826 * <p> This method assigns a default {@link java.security.ProtectionDomain
827 * ProtectionDomain} to the newly defined class. The
828 * {@code ProtectionDomain} is effectively granted the same set of
829 * permissions returned when {@link
830 * java.security.Policy#getPermissions(java.security.CodeSource)
831 * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
832 * is invoked. The default protection domain is created on the first invocation
833 * of {@link #defineClass(String, byte[], int, int) defineClass},
834 * and re-used on subsequent invocations.
835 *
836 * <p> To assign a specific {@code ProtectionDomain} to the class, use
837 * the {@link #defineClass(String, byte[], int, int,
838 * java.security.ProtectionDomain) defineClass} method that takes a
839 * {@code ProtectionDomain} as one of its arguments. </p>
840 *
841 * <p>
842 * This method defines a package in this class loader corresponding to the
843 * package of the {@code Class} (if such a package has not already been defined
844 * in this class loader). The name of the defined package is derived from
845 * the <a href="#binary-name">binary name</a> of the class specified by
846 * the byte array {@code b}.
847 * Other properties of the defined package are as specified by {@link Package}.
848 *
849 * @param name
850 * The expected <a href="#binary-name">binary name</a> of the class, or
851 * {@code null} if not known
852 *
853 * @param b
854 * The bytes that make up the class data. The bytes in positions
855 * {@code off} through {@code off+len-1} should have the format
856 * of a valid class file as defined by
857 * <cite>The Java Virtual Machine Specification</cite>.
858 *
859 * @param off
860 * The start offset in {@code b} of the class data
861 *
862 * @param len
863 * The length of the class data
864 *
865 * @return The {@code Class} object that was created from the specified
866 * class data.
867 *
868 * @throws ClassFormatError
869 * If the data did not contain a valid class
870 *
871 * @throws IndexOutOfBoundsException
872 * If either {@code off} or {@code len} is negative, or if
873 * {@code off+len} is greater than {@code b.length}.
874 *
875 * @throws SecurityException
876 * If an attempt is made to add this class to a package that
877 * contains classes that were signed by a different set of
878 * certificates than this class (which is unsigned), or if
879 * {@code name} begins with "{@code java.}".
880 *
881 * @see #loadClass(String, boolean)
882 * @see #resolveClass(Class)
883 * @see java.security.CodeSource
884 * @see java.security.SecureClassLoader
885 *
886 * @since 1.1
887 */
888 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
889 throws ClassFormatError
890 {
891 return defineClass(name, b, off, len, null);
892 }
893
894 /* Determine protection domain, and check that:
895 - not define java.* class,
896 - signer of this class matches signers for the rest of the classes in
897 package.
898 */
899 private ProtectionDomain preDefineClass(String name,
900 ProtectionDomain pd)
901 {
902 if (!checkName(name))
903 throw new NoClassDefFoundError("IllegalName: " + name);
904
905 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
906 // relies on the fact that spoofing is impossible if a class has a name
907 // of the form "java.*"
908 if ((name != null) && name.startsWith("java.")
909 && this != getBuiltinPlatformClassLoader()) {
910 throw new SecurityException
911 ("Prohibited package name: " +
912 name.substring(0, name.lastIndexOf('.')));
913 }
914 if (pd == null) {
915 pd = defaultDomain;
916 }
917
918 if (name != null) {
919 checkCerts(name, pd.getCodeSource());
920 }
921
922 return pd;
923 }
924
925 private String defineClassSourceLocation(ProtectionDomain pd) {
926 CodeSource cs = pd.getCodeSource();
927 String source = null;
928 if (cs != null && cs.getLocation() != null) {
929 source = cs.getLocation().toString();
930 }
931 return source;
932 }
933
934 private void postDefineClass(Class<?> c, ProtectionDomain pd) {
935 // define a named package, if not present
936 getNamedPackage(c.getPackageName(), c.getModule());
937
938 if (pd.getCodeSource() != null) {
939 Certificate certs[] = pd.getCodeSource().getCertificates();
940 if (certs != null)
941 setSigners(c, certs);
942 }
943 }
944
945 /**
946 * Converts an array of bytes into an instance of class {@code Class},
947 * with a given {@code ProtectionDomain}.
948 *
949 * <p> If the given {@code ProtectionDomain} is {@code null},
950 * then a default protection domain will be assigned to the class as specified
951 * in the documentation for {@link #defineClass(String, byte[], int, int)}.
952 * Before the class can be used it must be resolved.
953 *
954 * <p> The first class defined in a package determines the exact set of
955 * certificates that all subsequent classes defined in that package must
956 * contain. The set of certificates for a class is obtained from the
957 * {@link java.security.CodeSource CodeSource} within the
958 * {@code ProtectionDomain} of the class. Any classes added to that
959 * package must contain the same set of certificates or a
960 * {@code SecurityException} will be thrown. Note that if
961 * {@code name} is {@code null}, this check is not performed.
962 * You should always pass in the <a href="#binary-name">binary name</a> of the
963 * class you are defining as well as the bytes. This ensures that the
964 * class you are defining is indeed the class you think it is.
965 *
966 * <p> If the specified {@code name} begins with "{@code java.}", it can
967 * only be defined by the {@linkplain #getPlatformClassLoader()
968 * platform class loader} or its ancestors; otherwise {@code SecurityException}
969 * will be thrown. If {@code name} is not {@code null}, it must be equal to
970 * the <a href="#binary-name">binary name</a> of the class
971 * specified by the byte array {@code b}, otherwise a {@link
972 * NoClassDefFoundError NoClassDefFoundError} will be thrown.
973 *
974 * <p> This method defines a package in this class loader corresponding to the
975 * package of the {@code Class} (if such a package has not already been defined
976 * in this class loader). The name of the defined package is derived from
977 * the <a href="#binary-name">binary name</a> of the class specified by
978 * the byte array {@code b}.
979 * Other properties of the defined package are as specified by {@link Package}.
980 *
981 * @param name
982 * The expected <a href="#binary-name">binary name</a> of the class, or
983 * {@code null} if not known
984 *
985 * @param b
986 * The bytes that make up the class data. The bytes in positions
987 * {@code off} through {@code off+len-1} should have the format
988 * of a valid class file as defined by
989 * <cite>The Java Virtual Machine Specification</cite>.
990 *
991 * @param off
992 * The start offset in {@code b} of the class data
993 *
994 * @param len
995 * The length of the class data
996 *
997 * @param protectionDomain
998 * The {@code ProtectionDomain} of the class
999 *
1000 * @return The {@code Class} object created from the data,
1001 * and {@code ProtectionDomain}.
1002 *
1003 * @throws ClassFormatError
1004 * If the data did not contain a valid class
1005 *
1006 * @throws NoClassDefFoundError
1007 * If {@code name} is not {@code null} and not equal to the
1008 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
1009 *
1010 * @throws IndexOutOfBoundsException
1011 * If either {@code off} or {@code len} is negative, or if
1012 * {@code off+len} is greater than {@code b.length}.
1013 *
1014 * @throws SecurityException
1015 * If an attempt is made to add this class to a package that
1016 * contains classes that were signed by a different set of
1017 * certificates than this class, or if {@code name} begins with
1018 * "{@code java.}" and this class loader is not the platform
1019 * class loader or its ancestor.
1020 */
1021 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
1022 ProtectionDomain protectionDomain)
1023 throws ClassFormatError
1024 {
1025 protectionDomain = preDefineClass(name, protectionDomain);
1026 String source = defineClassSourceLocation(protectionDomain);
1027 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
1028 postDefineClass(c, protectionDomain);
1029 return c;
1030 }
1031
1032 /**
1033 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
1034 * of class {@code Class}, with the given {@code ProtectionDomain}.
1035 * If the given {@code ProtectionDomain} is {@code null}, then a default
1036 * protection domain will be assigned to the class as
1037 * specified in the documentation for {@link #defineClass(String, byte[],
1038 * int, int)}. Before the class can be used it must be resolved.
1039 *
1040 * <p>The rules about the first class defined in a package determining the
1041 * set of certificates for the package, the restrictions on class names,
1042 * and the defined package of the class
1043 * are identical to those specified in the documentation for {@link
1044 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
1045 *
1046 * <p> An invocation of this method of the form
1047 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
1048 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
1049 * result as the statements
1050 *
1051 *<p> <code>
1052 * ...<br>
1053 * byte[] temp = new byte[bBuffer.{@link
1054 * java.nio.ByteBuffer#remaining remaining}()];<br>
1055 * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
1056 * get}(temp);<br>
1057 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
1058 * cl.defineClass}(name, temp, 0,
1059 * temp.length, pd);<br>
1060 * </code></p>
1061 *
1062 * @param name
1063 * The expected <a href="#binary-name">binary name</a>. of the class, or
1064 * {@code null} if not known
1065 *
1066 * @param b
1067 * The bytes that make up the class data. The bytes from positions
1068 * {@code b.position()} through {@code b.position() + b.limit() -1
1069 * } should have the format of a valid class file as defined by
1070 * <cite>The Java Virtual Machine Specification</cite>.
1071 *
1072 * @param protectionDomain
1073 * The {@code ProtectionDomain} of the class, or {@code null}.
1074 *
1075 * @return The {@code Class} object created from the data,
1076 * and {@code ProtectionDomain}.
1077 *
1078 * @throws ClassFormatError
1079 * If the data did not contain a valid class.
1080 *
1081 * @throws NoClassDefFoundError
1082 * If {@code name} is not {@code null} and not equal to the
1083 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
1084 *
1085 * @throws SecurityException
1086 * If an attempt is made to add this class to a package that
1087 * contains classes that were signed by a different set of
1088 * certificates than this class, or if {@code name} begins with
1089 * "{@code java.}".
1090 *
1091 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
1092 *
1093 * @since 1.5
1094 */
1095 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
1096 ProtectionDomain protectionDomain)
1097 throws ClassFormatError
1098 {
1099 int len = b.remaining();
1100
1101 // Use byte[] if not a direct ByteBuffer:
1102 if (!b.isDirect()) {
1103 if (b.hasArray()) {
1104 return defineClass(name, b.array(),
1105 b.position() + b.arrayOffset(), len,
1106 protectionDomain);
1107 } else {
1108 // no array, or read-only array
1109 byte[] tb = new byte[len];
1110 b.get(tb); // get bytes out of byte buffer.
1111 return defineClass(name, tb, 0, len, protectionDomain);
1112 }
1113 }
1114
1115 protectionDomain = preDefineClass(name, protectionDomain);
1116 String source = defineClassSourceLocation(protectionDomain);
1117 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
1118 postDefineClass(c, protectionDomain);
1119 return c;
1120 }
1121
1122 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
1123 ProtectionDomain pd, String source);
1124
1125 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
1126 int off, int len, ProtectionDomain pd,
1127 String source);
1128
1129 /**
1130 * Defines a class of the given flags via Lookup.defineClass.
1131 *
1132 * @param loader the defining loader
1133 * @param lookup nest host of the Class to be defined
1134 * @param name the binary name or {@code null} if not findable
1135 * @param b class bytes
1136 * @param off the start offset in {@code b} of the class bytes
1137 * @param len the length of the class bytes
1138 * @param pd protection domain
1139 * @param initialize initialize the class
1140 * @param flags flags
1141 * @param classData class data
1142 */
1143 static native Class<?> defineClass0(ClassLoader loader,
1144 Class<?> lookup,
1145 String name,
1146 byte[] b, int off, int len,
1147 ProtectionDomain pd,
1148 boolean initialize,
1149 int flags,
1150 Object classData);
1151
1152 // true if the name is null or has the potential to be a valid binary name
1153 private static boolean checkName(String name) {
1154 if ((name == null) || (name.isEmpty()))
1155 return true;
1156 if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
1157 return false;
1158 return true;
1159 }
1160
1161 private void checkCerts(String name, CodeSource cs) {
1162 int i = name.lastIndexOf('.');
1163 String pname = (i == -1) ? "" : name.substring(0, i);
1164
1165 Certificate[] certs = null;
1166 if (cs != null) {
1167 certs = cs.getCertificates();
1168 }
1169 certs = certs == null ? nocerts : certs;
1170 Certificate[] pcerts = package2certs.putIfAbsent(pname, certs);
1171 if (pcerts != null && !compareCerts(pcerts, certs)) {
1172 throw new SecurityException("class \"" + name
1173 + "\"'s signer information does not match signer information"
1174 + " of other classes in the same package");
1175 }
1176 }
1177
1178 /**
1179 * check to make sure the certs for the new class (certs) are the same as
1180 * the certs for the first class inserted in the package (pcerts)
1181 */
1182 private boolean compareCerts(Certificate[] pcerts, Certificate[] certs) {
1183 // empty array fast-path
1184 if (certs.length == 0)
1185 return pcerts.length == 0;
1186
1187 // the length must be the same at this point
1188 if (certs.length != pcerts.length)
1189 return false;
1190
1191 // go through and make sure all the certs in one array
1192 // are in the other and vice-versa.
1193 boolean match;
1194 for (Certificate cert : certs) {
1195 match = false;
1196 for (Certificate pcert : pcerts) {
1197 if (cert.equals(pcert)) {
1198 match = true;
1199 break;
1200 }
1201 }
1202 if (!match) return false;
1203 }
1204
1205 // now do the same for pcerts
1206 for (Certificate pcert : pcerts) {
1207 match = false;
1208 for (Certificate cert : certs) {
1209 if (pcert.equals(cert)) {
1210 match = true;
1211 break;
1212 }
1213 }
1214 if (!match) return false;
1215 }
1216
1217 return true;
1218 }
1219
1220 /**
1221 * Links the specified class. This (misleadingly named) method may be
1222 * used by a class loader to link a class. If the class {@code c} has
1223 * already been linked, then this method simply returns. Otherwise, the
1224 * class is linked as described in the "Execution" chapter of
1225 * <cite>The Java Language Specification</cite>.
1226 *
1227 * @param c
1228 * The class to link
1229 *
1230 * @throws NullPointerException
1231 * If {@code c} is {@code null}.
1232 *
1233 * @see #defineClass(String, byte[], int, int)
1234 */
1235 protected final void resolveClass(Class<?> c) {
1236 if (c == null) {
1237 throw new NullPointerException();
1238 }
1239 }
1240
1241 /**
1242 * Finds a class with the specified <a href="#binary-name">binary name</a>,
1243 * loading it if necessary.
1244 *
1245 * <p> This method loads the class through the system class loader (see
1246 * {@link #getSystemClassLoader()}). The {@code Class} object returned
1247 * might have more than one {@code ClassLoader} associated with it.
1248 * Subclasses of {@code ClassLoader} need not usually invoke this method,
1249 * because most class loaders need to override just {@link
1250 * #findClass(String)}. </p>
1251 *
1252 * @param name
1253 * The <a href="#binary-name">binary name</a> of the class
1254 *
1255 * @return The {@code Class} object for the specified {@code name}
1256 *
1257 * @throws ClassNotFoundException
1258 * If the class could not be found
1259 *
1260 * @see #ClassLoader(ClassLoader)
1261 * @see #getParent()
1262 */
1263 protected final Class<?> findSystemClass(String name)
1264 throws ClassNotFoundException
1265 {
1266 return getSystemClassLoader().loadClass(name);
1267 }
1268
1269 /**
1270 * Returns a class loaded by the bootstrap class loader;
1271 * or return null if not found.
1272 */
1273 static Class<?> findBootstrapClassOrNull(String name) {
1274 if (!checkName(name)) return null;
1275
1276 return findBootstrapClass(name);
1277 }
1278
1279 // return null if not found
1280 private static native Class<?> findBootstrapClass(String name);
1281
1282 /**
1283 * Returns the class with the given <a href="#binary-name">binary name</a> if this
1284 * loader has been recorded by the Java virtual machine as an initiating
1285 * loader of a class with that <a href="#binary-name">binary name</a>. Otherwise
1286 * {@code null} is returned.
1287 *
1288 * @param name
1289 * The <a href="#binary-name">binary name</a> of the class
1290 *
1291 * @return The {@code Class} object, or {@code null} if the class has
1292 * not been loaded
1293 *
1294 * @since 1.1
1295 */
1296 protected final Class<?> findLoadedClass(String name) {
1297 if (!checkName(name))
1298 return null;
1299 return findLoadedClass0(name);
1300 }
1301
1302 private final native Class<?> findLoadedClass0(String name);
1303
1304 /**
1305 * Sets the signers of a class. This should be invoked after defining a
1306 * class.
1307 *
1308 * @param c
1309 * The {@code Class} object
1310 *
1311 * @param signers
1312 * The signers for the class
1313 *
1314 * @since 1.1
1315 */
1316 protected final void setSigners(Class<?> c, Object[] signers) {
1317 c.setSigners(signers);
1318 }
1319
1320
1321 // -- Resources --
1322
1323 /**
1324 * Returns a URL to a resource in a module defined to this class loader.
1325 * Class loader implementations that support loading from modules
1326 * should override this method.
1327 *
1328 * @apiNote This method is the basis for the {@link
1329 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
1330 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
1331 * Module.getResourceAsStream} methods. It is not subject to the rules for
1332 * encapsulation specified by {@code Module.getResourceAsStream}.
1333 *
1334 * @implSpec The default implementation attempts to find the resource by
1335 * invoking {@link #findResource(String)} when the {@code moduleName} is
1336 * {@code null}. It otherwise returns {@code null}.
1337 *
1338 * @param moduleName
1339 * The module name; or {@code null} to find a resource in the
1340 * {@linkplain #getUnnamedModule() unnamed module} for this
1341 * class loader
1342 * @param name
1343 * The resource name
1344 *
1345 * @return A URL to the resource; {@code null} if the resource could not be
1346 * found, a URL could not be constructed to locate the resource,
1347 * access to the resource is denied by the security manager, or
1348 * there isn't a module of the given name defined to the class
1349 * loader.
1350 *
1351 * @throws IOException
1352 * If I/O errors occur
1353 *
1354 * @see java.lang.module.ModuleReader#find(String)
1355 * @since 9
1356 */
1357 protected URL findResource(String moduleName, String name) throws IOException {
1358 if (moduleName == null) {
1359 return findResource(name);
1360 } else {
1361 return null;
1362 }
1363 }
1364
1365 /**
1366 * Finds the resource with the given name. A resource is some data
1367 * (images, audio, text, etc) that can be accessed by class code in a way
1368 * that is independent of the location of the code.
1369 *
1370 * <p> The name of a resource is a '{@code /}'-separated path name that
1371 * identifies the resource. </p>
1372 *
1373 * <p> Resources in named modules are subject to the encapsulation rules
1374 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1375 * Additionally, and except for the special case where the resource has a
1376 * name ending with "{@code .class}", this method will only find resources in
1377 * packages of named modules when the package is {@link Module#isOpen(String)
1378 * opened} unconditionally (even if the caller of this method is in the
1379 * same module as the resource). </p>
1380 *
1381 * @implSpec The default implementation will first search the parent class
1382 * loader for the resource; if the parent is {@code null} the path of the
1383 * class loader built into the virtual machine is searched. If not found,
1384 * this method will invoke {@link #findResource(String)} to find the resource.
1385 *
1386 * @apiNote Where several modules are defined to the same class loader,
1387 * and where more than one module contains a resource with the given name,
1388 * then the ordering that modules are searched is not specified and may be
1389 * very unpredictable.
1390 * When overriding this method it is recommended that an implementation
1391 * ensures that any delegation is consistent with the {@link
1392 * #getResources(java.lang.String) getResources(String)} method.
1393 *
1394 * @param name
1395 * The resource name
1396 *
1397 * @return {@code URL} object for reading the resource; {@code null} if
1398 * the resource could not be found, a {@code URL} could not be
1399 * constructed to locate the resource, the resource is in a package
1400 * that is not opened unconditionally, or access to the resource is
1401 * denied by the security manager.
1402 *
1403 * @throws NullPointerException If {@code name} is {@code null}
1404 *
1405 * @since 1.1
1406 */
1407 public URL getResource(String name) {
1408 Objects.requireNonNull(name);
1409 URL url;
1410 if (parent != null) {
1411 url = parent.getResource(name);
1412 } else {
1413 url = BootLoader.findResource(name);
1414 }
1415 if (url == null) {
1416 url = findResource(name);
1417 }
1418 return url;
1419 }
1420
1421 /**
1422 * Finds all the resources with the given name. A resource is some data
1423 * (images, audio, text, etc) that can be accessed by class code in a way
1424 * that is independent of the location of the code.
1425 *
1426 * <p> The name of a resource is a {@code /}-separated path name that
1427 * identifies the resource. </p>
1428 *
1429 * <p> Resources in named modules are subject to the encapsulation rules
1430 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1431 * Additionally, and except for the special case where the resource has a
1432 * name ending with "{@code .class}", this method will only find resources in
1433 * packages of named modules when the package is {@link Module#isOpen(String)
1434 * opened} unconditionally (even if the caller of this method is in the
1435 * same module as the resource). </p>
1436 *
1437 * @implSpec The default implementation will first search the parent class
1438 * loader for the resource; if the parent is {@code null} the path of the
1439 * class loader built into the virtual machine is searched. It then
1440 * invokes {@link #findResources(String)} to find the resources with the
1441 * name in this class loader. It returns an enumeration whose elements
1442 * are the URLs found by searching the parent class loader followed by
1443 * the elements found with {@code findResources}.
1444 *
1445 * @apiNote Where several modules are defined to the same class loader,
1446 * and where more than one module contains a resource with the given name,
1447 * then the ordering is not specified and may be very unpredictable.
1448 * When overriding this method it is recommended that an
1449 * implementation ensures that any delegation is consistent with the {@link
1450 * #getResource(java.lang.String) getResource(String)} method. This should
1451 * ensure that the first element returned by the Enumeration's
1452 * {@code nextElement} method is the same resource that the
1453 * {@code getResource(String)} method would return.
1454 *
1455 * @param name
1456 * The resource name
1457 *
1458 * @return An enumeration of {@link java.net.URL URL} objects for the
1459 * resource. If no resources could be found, the enumeration will
1460 * be empty. Resources for which a {@code URL} cannot be
1461 * constructed, are in a package that is not opened
1462 * unconditionally, or access to the resource is denied by the
1463 * security manager, are not returned in the enumeration.
1464 *
1465 * @throws IOException
1466 * If I/O errors occur
1467 * @throws NullPointerException If {@code name} is {@code null}
1468 *
1469 * @since 1.2
1470 */
1471 public Enumeration<URL> getResources(String name) throws IOException {
1472 Objects.requireNonNull(name);
1473 @SuppressWarnings("unchecked")
1474 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1475 if (parent != null) {
1476 tmp[0] = parent.getResources(name);
1477 } else {
1478 tmp[0] = BootLoader.findResources(name);
1479 }
1480 tmp[1] = findResources(name);
1481
1482 return new CompoundEnumeration<>(tmp);
1483 }
1484
1485 /**
1486 * Returns a stream whose elements are the URLs of all the resources with
1487 * the given name. A resource is some data (images, audio, text, etc) that
1488 * can be accessed by class code in a way that is independent of the
1489 * location of the code.
1490 *
1491 * <p> The name of a resource is a {@code /}-separated path name that
1492 * identifies the resource.
1493 *
1494 * <p> The resources will be located when the returned stream is evaluated.
1495 * If the evaluation results in an {@code IOException} then the I/O
1496 * exception is wrapped in an {@link UncheckedIOException} that is then
1497 * thrown.
1498 *
1499 * <p> Resources in named modules are subject to the encapsulation rules
1500 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1501 * Additionally, and except for the special case where the resource has a
1502 * name ending with "{@code .class}", this method will only find resources in
1503 * packages of named modules when the package is {@link Module#isOpen(String)
1504 * opened} unconditionally (even if the caller of this method is in the
1505 * same module as the resource). </p>
1506 *
1507 * @implSpec The default implementation invokes {@link #getResources(String)
1508 * getResources} to find all the resources with the given name and returns
1509 * a stream with the elements in the enumeration as the source.
1510 *
1511 * @apiNote When overriding this method it is recommended that an
1512 * implementation ensures that any delegation is consistent with the {@link
1513 * #getResource(java.lang.String) getResource(String)} method. This should
1514 * ensure that the first element returned by the stream is the same
1515 * resource that the {@code getResource(String)} method would return.
1516 *
1517 * @param name
1518 * The resource name
1519 *
1520 * @return A stream of resource {@link java.net.URL URL} objects. If no
1521 * resources could be found, the stream will be empty. Resources
1522 * for which a {@code URL} cannot be constructed, are in a package
1523 * that is not opened unconditionally, or access to the resource
1524 * is denied by the security manager, will not be in the stream.
1525 *
1526 * @throws NullPointerException If {@code name} is {@code null}
1527 *
1528 * @since 9
1529 */
1530 public Stream<URL> resources(String name) {
1531 Objects.requireNonNull(name);
1532 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
1533 Supplier<Spliterator<URL>> si = () -> {
1534 try {
1535 return Spliterators.spliteratorUnknownSize(
1536 getResources(name).asIterator(), characteristics);
1537 } catch (IOException e) {
1538 throw new UncheckedIOException(e);
1539 }
1540 };
1541 return StreamSupport.stream(si, characteristics, false);
1542 }
1543
1544 /**
1545 * Finds the resource with the given name. Class loader implementations
1546 * should override this method.
1547 *
1548 * <p> For resources in named modules then the method must implement the
1549 * rules for encapsulation specified in the {@code Module} {@link
1550 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1551 * it must not find non-"{@code .class}" resources in packages of named
1552 * modules unless the package is {@link Module#isOpen(String) opened}
1553 * unconditionally. </p>
1554 *
1555 * @implSpec The default implementation returns {@code null}.
1556 *
1557 * @param name
1558 * The resource name
1559 *
1560 * @return {@code URL} object for reading the resource; {@code null} if
1561 * the resource could not be found, a {@code URL} could not be
1562 * constructed to locate the resource, the resource is in a package
1563 * that is not opened unconditionally, or access to the resource is
1564 * denied by the security manager.
1565 *
1566 * @since 1.2
1567 */
1568 protected URL findResource(String name) {
1569 return null;
1570 }
1571
1572 /**
1573 * Returns an enumeration of {@link java.net.URL URL} objects
1574 * representing all the resources with the given name. Class loader
1575 * implementations should override this method.
1576 *
1577 * <p> For resources in named modules then the method must implement the
1578 * rules for encapsulation specified in the {@code Module} {@link
1579 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1580 * it must not find non-"{@code .class}" resources in packages of named
1581 * modules unless the package is {@link Module#isOpen(String) opened}
1582 * unconditionally. </p>
1583 *
1584 * @implSpec The default implementation returns an enumeration that
1585 * contains no elements.
1586 *
1587 * @param name
1588 * The resource name
1589 *
1590 * @return An enumeration of {@link java.net.URL URL} objects for
1591 * the resource. If no resources could be found, the enumeration
1592 * will be empty. Resources for which a {@code URL} cannot be
1593 * constructed, are in a package that is not opened unconditionally,
1594 * or access to the resource is denied by the security manager,
1595 * are not returned in the enumeration.
1596 *
1597 * @throws IOException
1598 * If I/O errors occur
1599 *
1600 * @since 1.2
1601 */
1602 protected Enumeration<URL> findResources(String name) throws IOException {
1603 return Collections.emptyEnumeration();
1604 }
1605
1606 /**
1607 * Registers the caller as
1608 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
1609 * The registration succeeds if and only if all of the following
1610 * conditions are met:
1611 * <ol>
1612 * <li> no instance of the caller has been created</li>
1613 * <li> all of the super classes (except class Object) of the caller are
1614 * registered as parallel capable</li>
1615 * </ol>
1616 * <p>Note that once a class loader is registered as parallel capable, there
1617 * is no way to change it back.</p>
1618 * <p>
1619 * In cases where this method is called from a context where the caller is
1620 * not a subclass of {@code ClassLoader} or there is no caller frame on the
1621 * stack (e.g. when called directly from a JNI attached thread),
1622 * {@code IllegalCallerException} is thrown.
1623 * </p>
1624 *
1625 * @return {@code true} if the caller is successfully registered as
1626 * parallel capable and {@code false} if otherwise.
1627 * @throws IllegalCallerException if the caller is not a subclass of {@code ClassLoader}
1628 *
1629 * @see #isRegisteredAsParallelCapable()
1630 *
1631 * @since 1.7
1632 */
1633 @CallerSensitive
1634 protected static boolean registerAsParallelCapable() {
1635 return registerAsParallelCapable(Reflection.getCallerClass());
1636 }
1637
1638 // Caller-sensitive adapter method for reflective invocation
1639 @CallerSensitiveAdapter
1640 private static boolean registerAsParallelCapable(Class<?> caller) {
1641 if ((caller == null) || !ClassLoader.class.isAssignableFrom(caller)) {
1642 throw new IllegalCallerException(caller + " not a subclass of ClassLoader");
1643 }
1644 return ParallelLoaders.register(caller.asSubclass(ClassLoader.class));
1645 }
1646
1647 /**
1648 * Returns {@code true} if this class loader is registered as
1649 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
1650 * {@code false}.
1651 *
1652 * @return {@code true} if this class loader is parallel capable,
1653 * otherwise {@code false}.
1654 *
1655 * @see #registerAsParallelCapable()
1656 *
1657 * @since 9
1658 */
1659 public final boolean isRegisteredAsParallelCapable() {
1660 return ParallelLoaders.isRegistered(this.getClass());
1661 }
1662
1663 /**
1664 * Find a resource of the specified name from the search path used to load
1665 * classes. This method locates the resource through the system class
1666 * loader (see {@link #getSystemClassLoader()}).
1667 *
1668 * <p> Resources in named modules are subject to the encapsulation rules
1669 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1670 * Additionally, and except for the special case where the resource has a
1671 * name ending with "{@code .class}", this method will only find resources in
1672 * packages of named modules when the package is {@link Module#isOpen(String)
1673 * opened} unconditionally. </p>
1674 *
1675 * @param name
1676 * The resource name
1677 *
1678 * @return A {@link java.net.URL URL} to the resource; {@code
1679 * null} if the resource could not be found, a URL could not be
1680 * constructed to locate the resource, the resource is in a package
1681 * that is not opened unconditionally or access to the resource is
1682 * denied by the security manager.
1683 *
1684 * @since 1.1
1685 */
1686 public static URL getSystemResource(String name) {
1687 return getSystemClassLoader().getResource(name);
1688 }
1689
1690 /**
1691 * Finds all resources of the specified name from the search path used to
1692 * load classes. The resources thus found are returned as an
1693 * {@link java.util.Enumeration Enumeration} of {@link
1694 * java.net.URL URL} objects.
1695 *
1696 * <p> The search order is described in the documentation for {@link
1697 * #getSystemResource(String)}. </p>
1698 *
1699 * <p> Resources in named modules are subject to the encapsulation rules
1700 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1701 * Additionally, and except for the special case where the resource has a
1702 * name ending with "{@code .class}", this method will only find resources in
1703 * packages of named modules when the package is {@link Module#isOpen(String)
1704 * opened} unconditionally. </p>
1705 *
1706 * @param name
1707 * The resource name
1708 *
1709 * @return An enumeration of {@link java.net.URL URL} objects for
1710 * the resource. If no resources could be found, the enumeration
1711 * will be empty. Resources for which a {@code URL} cannot be
1712 * constructed, are in a package that is not opened unconditionally,
1713 * or access to the resource is denied by the security manager,
1714 * are not returned in the enumeration.
1715 *
1716 * @throws IOException
1717 * If I/O errors occur
1718 *
1719 * @since 1.2
1720 */
1721 public static Enumeration<URL> getSystemResources(String name)
1722 throws IOException
1723 {
1724 return getSystemClassLoader().getResources(name);
1725 }
1726
1727 /**
1728 * Returns an input stream for reading the specified resource.
1729 *
1730 * <p> The search order is described in the documentation for {@link
1731 * #getResource(String)}. </p>
1732 *
1733 * <p> Resources in named modules are subject to the encapsulation rules
1734 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1735 * Additionally, and except for the special case where the resource has a
1736 * name ending with "{@code .class}", this method will only find resources in
1737 * packages of named modules when the package is {@link Module#isOpen(String)
1738 * opened} unconditionally. </p>
1739 *
1740 * @param name
1741 * The resource name
1742 *
1743 * @return An input stream for reading the resource; {@code null} if the
1744 * resource could not be found, the resource is in a package that
1745 * is not opened unconditionally, or access to the resource is
1746 * denied by the security manager.
1747 *
1748 * @throws NullPointerException If {@code name} is {@code null}
1749 *
1750 * @since 1.1
1751 */
1752 public InputStream getResourceAsStream(String name) {
1753 Objects.requireNonNull(name);
1754 URL url = getResource(name);
1755 try {
1756 return url != null ? url.openStream() : null;
1757 } catch (IOException e) {
1758 return null;
1759 }
1760 }
1761
1762 /**
1763 * Open for reading, a resource of the specified name from the search path
1764 * used to load classes. This method locates the resource through the
1765 * system class loader (see {@link #getSystemClassLoader()}).
1766 *
1767 * <p> Resources in named modules are subject to the encapsulation rules
1768 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1769 * Additionally, and except for the special case where the resource has a
1770 * name ending with "{@code .class}", this method will only find resources in
1771 * packages of named modules when the package is {@link Module#isOpen(String)
1772 * opened} unconditionally. </p>
1773 *
1774 * @param name
1775 * The resource name
1776 *
1777 * @return An input stream for reading the resource; {@code null} if the
1778 * resource could not be found, the resource is in a package that
1779 * is not opened unconditionally, or access to the resource is
1780 * denied by the security manager.
1781 *
1782 * @since 1.1
1783 */
1784 public static InputStream getSystemResourceAsStream(String name) {
1785 URL url = getSystemResource(name);
1786 try {
1787 return url != null ? url.openStream() : null;
1788 } catch (IOException e) {
1789 return null;
1790 }
1791 }
1792
1793
1794 // -- Hierarchy --
1795
1796 /**
1797 * Returns the parent class loader for delegation. Some implementations may
1798 * use {@code null} to represent the bootstrap class loader. This method
1799 * will return {@code null} in such implementations if this class loader's
1800 * parent is the bootstrap class loader.
1801 *
1802 * @return The parent {@code ClassLoader}
1803 *
1804 * @throws SecurityException
1805 * If a security manager is present, and the caller's class loader
1806 * is not {@code null} and is not an ancestor of this class loader,
1807 * and the caller does not have the
1808 * {@link RuntimePermission}{@code ("getClassLoader")}
1809 *
1810 * @since 1.2
1811 */
1812 @CallerSensitive
1813 public final ClassLoader getParent() {
1814 if (parent == null)
1815 return null;
1816 @SuppressWarnings("removal")
1817 SecurityManager sm = System.getSecurityManager();
1818 if (sm != null) {
1819 // Check access to the parent class loader
1820 // If the caller's class loader is same as this class loader,
1821 // permission check is performed.
1822 checkClassLoaderPermission(parent, Reflection.getCallerClass());
1823 }
1824 return parent;
1825 }
1826
1827 /**
1828 * Returns the unnamed {@code Module} for this class loader.
1829 *
1830 * @return The unnamed Module for this class loader
1831 *
1832 * @see Module#isNamed()
1833 * @since 9
1834 */
1835 public final Module getUnnamedModule() {
1836 return unnamedModule;
1837 }
1838
1839 /**
1840 * Returns the platform class loader. All
1841 * <a href="#builtinLoaders">platform classes</a> are visible to
1842 * the platform class loader.
1843 *
1844 * @implNote The name of the builtin platform class loader is
1845 * {@code "platform"}.
1846 *
1847 * @return The platform {@code ClassLoader}.
1848 *
1849 * @throws SecurityException
1850 * If a security manager is present, and the caller's class loader is
1851 * not {@code null}, and the caller's class loader is not the same
1852 * as or an ancestor of the platform class loader,
1853 * and the caller does not have the
1854 * {@link RuntimePermission}{@code ("getClassLoader")}
1855 *
1856 * @since 9
1857 */
1858 @CallerSensitive
1859 public static ClassLoader getPlatformClassLoader() {
1860 @SuppressWarnings("removal")
1861 SecurityManager sm = System.getSecurityManager();
1862 ClassLoader loader = getBuiltinPlatformClassLoader();
1863 if (sm != null) {
1864 checkClassLoaderPermission(loader, Reflection.getCallerClass());
1865 }
1866 return loader;
1867 }
1868
1869 /**
1870 * Returns the system class loader. This is the default
1871 * delegation parent for new {@code ClassLoader} instances, and is
1872 * typically the class loader used to start the application.
1873 *
1874 * <p> This method is first invoked early in the runtime's startup
1875 * sequence, at which point it creates the system class loader. This
1876 * class loader will be the context class loader for the main application
1877 * thread (for example, the thread that invokes the {@code main} method of
1878 * the main class).
1879 *
1880 * <p> The default system class loader is an implementation-dependent
1881 * instance of this class.
1882 *
1883 * <p> If the system property "{@systemProperty java.system.class.loader}"
1884 * is defined when this method is first invoked then the value of that
1885 * property is taken to be the name of a class that will be returned as the
1886 * system class loader. The class is loaded using the default system class
1887 * loader and must define a public constructor that takes a single parameter
1888 * of type {@code ClassLoader} which is used as the delegation parent. An
1889 * instance is then created using this constructor with the default system
1890 * class loader as the parameter. The resulting class loader is defined
1891 * to be the system class loader. During construction, the class loader
1892 * should take great care to avoid calling {@code getSystemClassLoader()}.
1893 * If circular initialization of the system class loader is detected then
1894 * an {@code IllegalStateException} is thrown.
1895 *
1896 * @implNote The system property to override the system class loader is not
1897 * examined until the VM is almost fully initialized. Code that executes
1898 * this method during startup should take care not to cache the return
1899 * value until the system is fully initialized.
1900 *
1901 * <p> The name of the built-in system class loader is {@code "app"}.
1902 * The system property "{@code java.class.path}" is read during early
1903 * initialization of the VM to determine the class path.
1904 * An empty value of "{@code java.class.path}" property is interpreted
1905 * differently depending on whether the initial module (the module
1906 * containing the main class) is named or unnamed:
1907 * If named, the built-in system class loader will have no class path and
1908 * will search for classes and resources using the application module path;
1909 * otherwise, if unnamed, it will set the class path to the current
1910 * working directory.
1911 *
1912 * <p> JAR files on the class path may contain a {@code Class-Path} manifest
1913 * attribute to specify dependent JAR files to be included in the class path.
1914 * {@code Class-Path} entries must meet certain conditions for validity (see
1915 * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute">
1916 * JAR File Specification</a> for details). Invalid {@code Class-Path}
1917 * entries are ignored. For debugging purposes, ignored entries can be
1918 * printed to the console if the
1919 * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system
1920 * property is set to {@code true}.
1921 *
1922 * @return The system {@code ClassLoader}
1923 *
1924 * @throws SecurityException
1925 * If a security manager is present, and the caller's class loader
1926 * is not {@code null} and is not the same as or an ancestor of the
1927 * system class loader, and the caller does not have the
1928 * {@link RuntimePermission}{@code ("getClassLoader")}
1929 *
1930 * @throws IllegalStateException
1931 * If invoked recursively during the construction of the class
1932 * loader specified by the "{@code java.system.class.loader}"
1933 * property.
1934 *
1935 * @throws Error
1936 * If the system property "{@code java.system.class.loader}"
1937 * is defined but the named class could not be loaded, the
1938 * provider class does not define the required constructor, or an
1939 * exception is thrown by that constructor when it is invoked. The
1940 * underlying cause of the error can be retrieved via the
1941 * {@link Throwable#getCause()} method.
1942 */
1943 @CallerSensitive
1944 public static ClassLoader getSystemClassLoader() {
1945 switch (VM.initLevel()) {
1946 case 0:
1947 case 1:
1948 case 2:
1949 // the system class loader is the built-in app class loader during startup
1950 return getBuiltinAppClassLoader();
1951 case 3:
1952 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
1953 throw new IllegalStateException(msg);
1954 default:
1955 // system fully initialized
1956 assert VM.isBooted() && scl != null;
1957 @SuppressWarnings("removal")
1958 SecurityManager sm = System.getSecurityManager();
1959 if (sm != null) {
1960 checkClassLoaderPermission(scl, Reflection.getCallerClass());
1961 }
1962 return scl;
1963 }
1964 }
1965
1966 static ClassLoader getBuiltinPlatformClassLoader() {
1967 return ClassLoaders.platformClassLoader();
1968 }
1969
1970 static ClassLoader getBuiltinAppClassLoader() {
1971 return ClassLoaders.appClassLoader();
1972 }
1973
1974 /*
1975 * Initialize the system class loader that may be a custom class on the
1976 * application class path or application module path.
1977 *
1978 * @see java.lang.System#initPhase3
1979 */
1980 static synchronized ClassLoader initSystemClassLoader() {
1981 if (VM.initLevel() != 3) {
1982 throw new InternalError("system class loader cannot be set at initLevel " +
1983 VM.initLevel());
1984 }
1985
1986 // detect recursive initialization
1987 if (scl != null) {
1988 throw new IllegalStateException("recursive invocation");
1989 }
1990
1991 ClassLoader builtinLoader = getBuiltinAppClassLoader();
1992
1993 // All are privileged frames. No need to call doPrivileged.
1994 String cn = System.getProperty("java.system.class.loader");
1995 if (cn != null) {
1996 try {
1997 // custom class loader is only supported to be loaded from unnamed module
1998 Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
1999 .getDeclaredConstructor(ClassLoader.class);
2000 scl = (ClassLoader) ctor.newInstance(builtinLoader);
2001 } catch (Exception e) {
2002 Throwable cause = e;
2003 if (e instanceof InvocationTargetException) {
2004 cause = e.getCause();
2005 if (cause instanceof Error) {
2006 throw (Error) cause;
2007 }
2008 }
2009 if (cause instanceof RuntimeException) {
2010 throw (RuntimeException) cause;
2011 }
2012 throw new Error(cause.getMessage(), cause);
2013 }
2014 } else {
2015 scl = builtinLoader;
2016 }
2017 return scl;
2018 }
2019
2020 // Returns true if the specified class loader can be found in this class
2021 // loader's delegation chain.
2022 boolean isAncestor(ClassLoader cl) {
2023 ClassLoader acl = this;
2024 do {
2025 acl = acl.parent;
2026 if (cl == acl) {
2027 return true;
2028 }
2029 } while (acl != null);
2030 return false;
2031 }
2032
2033 // Tests if class loader access requires "getClassLoader" permission
2034 // check. A class loader 'from' can access class loader 'to' if
2035 // class loader 'from' is same as class loader 'to' or an ancestor
2036 // of 'to'. The class loader in a system domain can access
2037 // any class loader.
2038 private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
2039 ClassLoader to)
2040 {
2041 if (from == to)
2042 return false;
2043
2044 if (from == null)
2045 return false;
2046
2047 return !to.isAncestor(from);
2048 }
2049
2050 // Returns the class's class loader, or null if none.
2051 static ClassLoader getClassLoader(Class<?> caller) {
2052 // This can be null if the VM is requesting it
2053 if (caller == null) {
2054 return null;
2055 }
2056 // Circumvent security check since this is package-private
2057 return caller.getClassLoader0();
2058 }
2059
2060 /*
2061 * Checks RuntimePermission("getClassLoader") permission
2062 * if caller's class loader is not null and caller's class loader
2063 * is not the same as or an ancestor of the given cl argument.
2064 */
2065 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
2066 @SuppressWarnings("removal")
2067 SecurityManager sm = System.getSecurityManager();
2068 if (sm != null) {
2069 // caller can be null if the VM is requesting it
2070 ClassLoader ccl = getClassLoader(caller);
2071 if (needsClassLoaderPermissionCheck(ccl, cl)) {
2072 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
2073 }
2074 }
2075 }
2076
2077 // The system class loader
2078 // @GuardedBy("ClassLoader.class")
2079 private static volatile ClassLoader scl;
2080
2081 // -- Package --
2082
2083 /**
2084 * Define a Package of the given Class object.
2085 *
2086 * If the given class represents an array type, a primitive type or void,
2087 * this method returns {@code null}.
2088 *
2089 * This method does not throw IllegalArgumentException.
2090 */
2091 Package definePackage(Class<?> c) {
2092 if (c.isPrimitive() || c.isArray()) {
2093 return null;
2094 }
2095
2096 return definePackage(c.getPackageName(), c.getModule());
2097 }
2098
2099 /**
2100 * Defines a Package of the given name and module
2101 *
2102 * This method does not throw IllegalArgumentException.
2103 *
2104 * @param name package name
2105 * @param m module
2106 */
2107 Package definePackage(String name, Module m) {
2108 if (name.isEmpty() && m.isNamed()) {
2109 throw new InternalError("unnamed package in " + m);
2110 }
2111
2112 // check if Package object is already defined
2113 NamedPackage pkg = packages.get(name);
2114 if (pkg instanceof Package)
2115 return (Package)pkg;
2116
2117 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
2118 }
2119
2120 /*
2121 * Returns a Package object for the named package
2122 */
2123 private Package toPackage(String name, NamedPackage p, Module m) {
2124 // define Package object if the named package is not yet defined
2125 if (p == null)
2126 return NamedPackage.toPackage(name, m);
2127
2128 // otherwise, replace the NamedPackage object with Package object
2129 if (p instanceof Package)
2130 return (Package)p;
2131
2132 return NamedPackage.toPackage(p.packageName(), p.module());
2133 }
2134
2135 /**
2136 * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}.
2137 * <p>
2138 * <a href="#binary-name">Package names</a> must be unique within a class loader and
2139 * cannot be redefined or changed once created.
2140 * <p>
2141 * If a class loader wishes to define a package with specific properties,
2142 * such as version information, then the class loader should call this
2143 * {@code definePackage} method before calling {@code defineClass}.
2144 * Otherwise, the
2145 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
2146 * method will define a package in this class loader corresponding to the package
2147 * of the newly defined class; the properties of this defined package are
2148 * specified by {@link Package}.
2149 *
2150 * @apiNote
2151 * A class loader that wishes to define a package for classes in a JAR
2152 * typically uses the specification and implementation titles, versions, and
2153 * vendors from the JAR's manifest. If the package is specified as
2154 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
2155 * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
2156 * If classes of package {@code 'p'} defined by this class loader
2157 * are loaded from multiple JARs, the {@code Package} object may contain
2158 * different information depending on the first class of package {@code 'p'}
2159 * defined and which JAR's manifest is read first to explicitly define
2160 * package {@code 'p'}.
2161 *
2162 * <p> It is strongly recommended that a class loader does not call this
2163 * method to explicitly define packages in <em>named modules</em>; instead,
2164 * the package will be automatically defined when a class is {@linkplain
2165 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
2166 * If it is desirable to define {@code Package} explicitly, it should ensure
2167 * that all packages in a named module are defined with the properties
2168 * specified by {@link Package}. Otherwise, some {@code Package} objects
2169 * in a named module may be for example sealed with different seal base.
2170 *
2171 * @param name
2172 * The <a href="#binary-name">package name</a>
2173 *
2174 * @param specTitle
2175 * The specification title
2176 *
2177 * @param specVersion
2178 * The specification version
2179 *
2180 * @param specVendor
2181 * The specification vendor
2182 *
2183 * @param implTitle
2184 * The implementation title
2185 *
2186 * @param implVersion
2187 * The implementation version
2188 *
2189 * @param implVendor
2190 * The implementation vendor
2191 *
2192 * @param sealBase
2193 * If not {@code null}, then this package is sealed with
2194 * respect to the given code source {@link java.net.URL URL}
2195 * object. Otherwise, the package is not sealed.
2196 *
2197 * @return The newly defined {@code Package} object
2198 *
2199 * @throws NullPointerException
2200 * if {@code name} is {@code null}.
2201 *
2202 * @throws IllegalArgumentException
2203 * if a package of the given {@code name} is already
2204 * defined by this class loader
2205 *
2206 *
2207 * @since 1.2
2208 *
2209 * @jvms 5.3 Creation and Loading
2210 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
2211 * The JAR File Specification: Package Sealing</a>
2212 */
2213 protected Package definePackage(String name, String specTitle,
2214 String specVersion, String specVendor,
2215 String implTitle, String implVersion,
2216 String implVendor, URL sealBase)
2217 {
2218 Objects.requireNonNull(name);
2219
2220 // definePackage is not final and may be overridden by custom class loader
2221 Package p = new Package(name, specTitle, specVersion, specVendor,
2222 implTitle, implVersion, implVendor,
2223 sealBase, this);
2224
2225 if (packages.putIfAbsent(name, p) != null)
2226 throw new IllegalArgumentException(name);
2227
2228 return p;
2229 }
2230
2231 /**
2232 * Returns a {@code Package} of the given <a href="#binary-name">name</a> that
2233 * has been defined by this class loader.
2234 *
2235 * @param name The <a href="#binary-name">package name</a>
2236 *
2237 * @return The {@code Package} of the given name that has been defined
2238 * by this class loader, or {@code null} if not found
2239 *
2240 * @throws NullPointerException
2241 * if {@code name} is {@code null}.
2242 *
2243 * @jvms 5.3 Creation and Loading
2244 *
2245 * @since 9
2246 */
2247 public final Package getDefinedPackage(String name) {
2248 Objects.requireNonNull(name, "name cannot be null");
2249
2250 NamedPackage p = packages.get(name);
2251 if (p == null)
2252 return null;
2253
2254 return definePackage(name, p.module());
2255 }
2256
2257 /**
2258 * Returns all of the {@code Package}s that have been defined by
2259 * this class loader. The returned array has no duplicated {@code Package}s
2260 * of the same name.
2261 *
2262 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
2263 * for consistency with the existing {@link #getPackages} method.
2264 *
2265 * @return The array of {@code Package} objects that have been defined by
2266 * this class loader; or a zero length array if no package has been
2267 * defined by this class loader.
2268 *
2269 * @jvms 5.3 Creation and Loading
2270 *
2271 * @since 9
2272 */
2273 public final Package[] getDefinedPackages() {
2274 return packages().toArray(Package[]::new);
2275 }
2276
2277 /**
2278 * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors.
2279 * <p>
2280 * If this class loader defines a {@code Package} of the given name,
2281 * the {@code Package} is returned. Otherwise, the ancestors of
2282 * this class loader are searched recursively (parent by parent)
2283 * for a {@code Package} of the given name.
2284 *
2285 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2286 * may delegate to the application class loader but the application class
2287 * loader is not its ancestor. When invoked on the platform class loader,
2288 * this method will not find packages defined to the application
2289 * class loader.
2290 *
2291 * @param name
2292 * The <a href="#binary-name">package name</a>
2293 *
2294 * @return The {@code Package} of the given name that has been defined by
2295 * this class loader or its ancestors, or {@code null} if not found.
2296 *
2297 * @throws NullPointerException
2298 * if {@code name} is {@code null}.
2299 *
2300 * @deprecated
2301 * If multiple class loaders delegate to each other and define classes
2302 * with the same package name, and one such loader relies on the lookup
2303 * behavior of {@code getPackage} to return a {@code Package} from
2304 * a parent loader, then the properties exposed by the {@code Package}
2305 * may not be as expected in the rest of the program.
2306 * For example, the {@code Package} will only expose annotations from the
2307 * {@code package-info.class} file defined by the parent loader, even if
2308 * annotations exist in a {@code package-info.class} file defined by
2309 * a child loader. A more robust approach is to use the
2310 * {@link ClassLoader#getDefinedPackage} method which returns
2311 * a {@code Package} for the specified class loader.
2312 *
2313 * @see ClassLoader#getDefinedPackage(String)
2314 *
2315 * @since 1.2
2316 */
2317 @Deprecated(since="9")
2318 protected Package getPackage(String name) {
2319 Package pkg = getDefinedPackage(name);
2320 if (pkg == null) {
2321 if (parent != null) {
2322 pkg = parent.getPackage(name);
2323 } else {
2324 pkg = BootLoader.getDefinedPackage(name);
2325 }
2326 }
2327 return pkg;
2328 }
2329
2330 /**
2331 * Returns all of the {@code Package}s that have been defined by
2332 * this class loader and its ancestors. The returned array may contain
2333 * more than one {@code Package} object of the same package name, each
2334 * defined by a different class loader in the class loader hierarchy.
2335 *
2336 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2337 * may delegate to the application class loader. In other words,
2338 * packages in modules defined to the application class loader may be
2339 * visible to the platform class loader. On the other hand,
2340 * the application class loader is not its ancestor and hence
2341 * when invoked on the platform class loader, this method will not
2342 * return any packages defined to the application class loader.
2343 *
2344 * @return The array of {@code Package} objects that have been defined by
2345 * this class loader and its ancestors
2346 *
2347 * @see ClassLoader#getDefinedPackages()
2348 *
2349 * @since 1.2
2350 */
2351 protected Package[] getPackages() {
2352 Stream<Package> pkgs = packages();
2353 ClassLoader ld = parent;
2354 while (ld != null) {
2355 pkgs = Stream.concat(ld.packages(), pkgs);
2356 ld = ld.parent;
2357 }
2358 return Stream.concat(BootLoader.packages(), pkgs)
2359 .toArray(Package[]::new);
2360 }
2361
2362
2363
2364 // package-private
2365
2366 /**
2367 * Returns a stream of Packages defined in this class loader
2368 */
2369 Stream<Package> packages() {
2370 return packages.values().stream()
2371 .map(p -> definePackage(p.packageName(), p.module()));
2372 }
2373
2374 // -- Native library access --
2375
2376 /**
2377 * Returns the absolute path name of a native library. The VM invokes this
2378 * method to locate the native libraries that belong to classes loaded with
2379 * this class loader. If this method returns {@code null}, the VM
2380 * searches the library along the path specified as the
2381 * "{@code java.library.path}" property.
2382 *
2383 * @param libname
2384 * The library name
2385 *
2386 * @return The absolute path of the native library
2387 *
2388 * @see System#loadLibrary(String)
2389 * @see System#mapLibraryName(String)
2390 *
2391 * @since 1.2
2392 */
2393 protected String findLibrary(String libname) {
2394 return null;
2395 }
2396
2397 private final NativeLibraries libraries = NativeLibraries.newInstance(this);
2398
2399 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
2400 static NativeLibrary loadLibrary(Class<?> fromClass, File file) {
2401 ClassLoader loader = (fromClass == null) ? null : fromClass.getClassLoader();
2402 NativeLibraries libs = loader != null ? loader.libraries : BootLoader.getNativeLibraries();
2403 NativeLibrary nl = libs.loadLibrary(fromClass, file);
2404 if (nl != null) {
2405 return nl;
2406 }
2407 throw new UnsatisfiedLinkError("Can't load library: " + file);
2408 }
2409 static NativeLibrary loadLibrary(Class<?> fromClass, String name) {
2410 ClassLoader loader = (fromClass == null) ? null : fromClass.getClassLoader();
2411 if (loader == null) {
2412 NativeLibrary nl = BootLoader.getNativeLibraries().loadLibrary(fromClass, name);
2413 if (nl != null) {
2414 return nl;
2415 }
2416 throw new UnsatisfiedLinkError("no " + name +
2417 " in system library path: " + StaticProperty.sunBootLibraryPath());
2418 }
2419
2420 NativeLibraries libs = loader.libraries;
2421 // First load from the file returned from ClassLoader::findLibrary, if found.
2422 String libfilename = loader.findLibrary(name);
2423 if (libfilename != null) {
2424 File libfile = new File(libfilename);
2425 if (!libfile.isAbsolute()) {
2426 throw new UnsatisfiedLinkError(
2427 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
2428 }
2429 NativeLibrary nl = libs.loadLibrary(fromClass, libfile);
2430 if (nl != null) {
2431 return nl;
2432 }
2433 throw new UnsatisfiedLinkError("Can't load " + libfilename);
2434 }
2435 // Then load from system library path and java library path
2436 NativeLibrary nl = libs.loadLibrary(fromClass, name);
2437 if (nl != null) {
2438 return nl;
2439 }
2440
2441 // Oops, it failed
2442 throw new UnsatisfiedLinkError("no " + name +
2443 " in java.library.path: " + StaticProperty.javaLibraryPath());
2444 }
2445
2446 /**
2447 * Invoked in the VM class linking code.
2448 * @param loader the class loader used to look up the native library symbol
2449 * @param clazz the class in which the native method is declared
2450 * @param entryName the native method's mangled name (this is the name used for the native lookup)
2451 * @param javaName the native method's declared name
2452 */
2453 static long findNative(ClassLoader loader, Class<?> clazz, String entryName, String javaName) {
2454 NativeLibraries nativeLibraries = nativeLibrariesFor(loader);
2455 long addr = nativeLibraries.find(entryName);
2456 if (addr != 0 && loader != null) {
2457 Reflection.ensureNativeAccess(clazz, clazz, javaName, true);
2458 }
2459 return addr;
2460 }
2461
2462 /*
2463 * This is also called by SymbolLookup::loaderLookup. In that case, we need
2464 * to avoid a restricted check, as that check has already been performed when
2465 * obtaining the lookup.
2466 */
2467 static NativeLibraries nativeLibrariesFor(ClassLoader loader) {
2468 if (loader == null) {
2469 return BootLoader.getNativeLibraries();
2470 } else {
2471 return loader.libraries;
2472 }
2473 }
2474
2475 // -- Assertion management --
2476
2477 final Object assertionLock;
2478
2479 // The default toggle for assertion checking.
2480 // @GuardedBy("assertionLock")
2481 private boolean defaultAssertionStatus = false;
2482
2483 // Maps String packageName to Boolean package default assertion status Note
2484 // that the default package is placed under a null map key. If this field
2485 // is null then we are delegating assertion status queries to the VM, i.e.,
2486 // none of this ClassLoader's assertion status modification methods have
2487 // been invoked.
2488 // @GuardedBy("assertionLock")
2489 private Map<String, Boolean> packageAssertionStatus = null;
2490
2491 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
2492 // field is null then we are delegating assertion status queries to the VM,
2493 // i.e., none of this ClassLoader's assertion status modification methods
2494 // have been invoked.
2495 // @GuardedBy("assertionLock")
2496 Map<String, Boolean> classAssertionStatus = null;
2497
2498 /**
2499 * Sets the default assertion status for this class loader. This setting
2500 * determines whether classes loaded by this class loader and initialized
2501 * in the future will have assertions enabled or disabled by default.
2502 * This setting may be overridden on a per-package or per-class basis by
2503 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
2504 * #setClassAssertionStatus(String, boolean)}.
2505 *
2506 * @param enabled
2507 * {@code true} if classes loaded by this class loader will
2508 * henceforth have assertions enabled by default, {@code false}
2509 * if they will have assertions disabled by default.
2510 *
2511 * @since 1.4
2512 */
2513 public void setDefaultAssertionStatus(boolean enabled) {
2514 synchronized (assertionLock) {
2515 if (classAssertionStatus == null)
2516 initializeJavaAssertionMaps();
2517
2518 defaultAssertionStatus = enabled;
2519 }
2520 }
2521
2522 /**
2523 * Sets the package default assertion status for the named package. The
2524 * package default assertion status determines the assertion status for
2525 * classes initialized in the future that belong to the named package or
2526 * any of its "subpackages".
2527 *
2528 * <p> A subpackage of a package named p is any package whose name begins
2529 * with "{@code p.}". For example, {@code javax.swing.text} is a
2530 * subpackage of {@code javax.swing}, and both {@code java.util} and
2531 * {@code java.lang.reflect} are subpackages of {@code java}.
2532 *
2533 * <p> In the event that multiple package defaults apply to a given class,
2534 * the package default pertaining to the most specific package takes
2535 * precedence over the others. For example, if {@code javax.lang} and
2536 * {@code javax.lang.reflect} both have package defaults associated with
2537 * them, the latter package default applies to classes in
2538 * {@code javax.lang.reflect}.
2539 *
2540 * <p> Package defaults take precedence over the class loader's default
2541 * assertion status, and may be overridden on a per-class basis by invoking
2542 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2543 *
2544 * @param packageName
2545 * The name of the package whose package default assertion status
2546 * is to be set. A {@code null} value indicates the unnamed
2547 * package that is "current"
2548 * (see section {@jls 7.4.2} of
2549 * <cite>The Java Language Specification</cite>.)
2550 *
2551 * @param enabled
2552 * {@code true} if classes loaded by this classloader and
2553 * belonging to the named package or any of its subpackages will
2554 * have assertions enabled by default, {@code false} if they will
2555 * have assertions disabled by default.
2556 *
2557 * @since 1.4
2558 */
2559 public void setPackageAssertionStatus(String packageName,
2560 boolean enabled) {
2561 synchronized (assertionLock) {
2562 if (packageAssertionStatus == null)
2563 initializeJavaAssertionMaps();
2564
2565 packageAssertionStatus.put(packageName, enabled);
2566 }
2567 }
2568
2569 /**
2570 * Sets the desired assertion status for the named top-level class in this
2571 * class loader and any nested classes contained therein. This setting
2572 * takes precedence over the class loader's default assertion status, and
2573 * over any applicable per-package default. This method has no effect if
2574 * the named class has already been initialized. (Once a class is
2575 * initialized, its assertion status cannot change.)
2576 *
2577 * <p> If the named class is not a top-level class, this invocation will
2578 * have no effect on the actual assertion status of any class. </p>
2579 *
2580 * @param className
2581 * The fully qualified class name of the top-level class whose
2582 * assertion status is to be set.
2583 *
2584 * @param enabled
2585 * {@code true} if the named class is to have assertions
2586 * enabled when (and if) it is initialized, {@code false} if the
2587 * class is to have assertions disabled.
2588 *
2589 * @since 1.4
2590 */
2591 public void setClassAssertionStatus(String className, boolean enabled) {
2592 synchronized (assertionLock) {
2593 if (classAssertionStatus == null)
2594 initializeJavaAssertionMaps();
2595
2596 classAssertionStatus.put(className, enabled);
2597 }
2598 }
2599
2600 /**
2601 * Sets the default assertion status for this class loader to
2602 * {@code false} and discards any package defaults or class assertion
2603 * status settings associated with the class loader. This method is
2604 * provided so that class loaders can be made to ignore any command line or
2605 * persistent assertion status settings and "start with a clean slate."
2606 *
2607 * @since 1.4
2608 */
2609 public void clearAssertionStatus() {
2610 /*
2611 * Whether or not "Java assertion maps" are initialized, set
2612 * them to empty maps, effectively ignoring any present settings.
2613 */
2614 synchronized (assertionLock) {
2615 classAssertionStatus = new HashMap<>();
2616 packageAssertionStatus = new HashMap<>();
2617 defaultAssertionStatus = false;
2618 }
2619 }
2620
2621 /**
2622 * Returns the assertion status that would be assigned to the specified
2623 * class if it were to be initialized at the time this method is invoked.
2624 * If the named class has had its assertion status set, the most recent
2625 * setting will be returned; otherwise, if any package default assertion
2626 * status pertains to this class, the most recent setting for the most
2627 * specific pertinent package default assertion status is returned;
2628 * otherwise, this class loader's default assertion status is returned.
2629 * </p>
2630 *
2631 * @param className
2632 * The fully qualified class name of the class whose desired
2633 * assertion status is being queried.
2634 *
2635 * @return The desired assertion status of the specified class.
2636 *
2637 * @see #setClassAssertionStatus(String, boolean)
2638 * @see #setPackageAssertionStatus(String, boolean)
2639 * @see #setDefaultAssertionStatus(boolean)
2640 *
2641 * @since 1.4
2642 */
2643 boolean desiredAssertionStatus(String className) {
2644 synchronized (assertionLock) {
2645 // assert classAssertionStatus != null;
2646 // assert packageAssertionStatus != null;
2647
2648 // Check for a class entry
2649 Boolean result = classAssertionStatus.get(className);
2650 if (result != null)
2651 return result.booleanValue();
2652
2653 // Check for most specific package entry
2654 int dotIndex = className.lastIndexOf('.');
2655 if (dotIndex < 0) { // default package
2656 result = packageAssertionStatus.get(null);
2657 if (result != null)
2658 return result.booleanValue();
2659 }
2660 while(dotIndex > 0) {
2661 className = className.substring(0, dotIndex);
2662 result = packageAssertionStatus.get(className);
2663 if (result != null)
2664 return result.booleanValue();
2665 dotIndex = className.lastIndexOf('.', dotIndex-1);
2666 }
2667
2668 // Return the classloader default
2669 return defaultAssertionStatus;
2670 }
2671 }
2672
2673 // Set up the assertions with information provided by the VM.
2674 // Note: Should only be called inside a synchronized block
2675 private void initializeJavaAssertionMaps() {
2676 // assert Thread.holdsLock(assertionLock);
2677
2678 classAssertionStatus = new HashMap<>();
2679 packageAssertionStatus = new HashMap<>();
2680 AssertionStatusDirectives directives = retrieveDirectives();
2681
2682 for(int i = 0; i < directives.classes.length; i++)
2683 classAssertionStatus.put(directives.classes[i],
2684 directives.classEnabled[i]);
2685
2686 for(int i = 0; i < directives.packages.length; i++)
2687 packageAssertionStatus.put(directives.packages[i],
2688 directives.packageEnabled[i]);
2689
2690 defaultAssertionStatus = directives.deflt;
2691 }
2692
2693 // Retrieves the assertion directives from the VM.
2694 private static native AssertionStatusDirectives retrieveDirectives();
2695
2696
2697 // -- Misc --
2698
2699 /**
2700 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
2701 * associated with this ClassLoader, creating it if it doesn't already exist.
2702 */
2703 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
2704 ConcurrentHashMap<?, ?> map = classLoaderValueMap;
2705 if (map == null) {
2706 map = new ConcurrentHashMap<>();
2707 boolean set = trySetObjectField("classLoaderValueMap", map);
2708 if (!set) {
2709 // beaten by someone else
2710 map = classLoaderValueMap;
2711 }
2712 }
2713 return map;
2714 }
2715
2716 // the storage for ClassLoaderValue(s) associated with this ClassLoader
2717 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
2718
2719 /**
2720 * Attempts to atomically set a volatile field in this object. Returns
2721 * {@code true} if not beaten by another thread. Avoids the use of
2722 * AtomicReferenceFieldUpdater in this class.
2723 */
2724 private boolean trySetObjectField(String name, Object obj) {
2725 Unsafe unsafe = Unsafe.getUnsafe();
2726 Class<?> k = ClassLoader.class;
2727 long offset;
2728 offset = unsafe.objectFieldOffset(k, name);
2729 return unsafe.compareAndSetReference(this, offset, null, obj);
2730 }
2731
2732 /**
2733 * Called by the VM, during -Xshare:dump
2734 */
2735 private void resetArchivedStates() {
2736 if (parallelLockMap != null) {
2737 parallelLockMap.clear();
2738 }
2739
2740 if (CDS.isDumpingPackages()) {
2741 if (System.getProperty("cds.debug.archived.packages") != null) {
2742 for (Map.Entry<String, NamedPackage> entry : packages.entrySet()) {
2743 String key = entry.getKey();
2744 NamedPackage value = entry.getValue();
2745 System.out.println("Archiving " +
2746 (value instanceof Package ? "Package" : "NamedPackage") +
2747 " \"" + key + "\" for " + this);
2748 }
2749 }
2750 } else {
2751 packages.clear();
2752 package2certs.clear();
2753 }
2754 classes.clear();
2755 classLoaderValueMap = null;
2756 }
2757 }
2758
2759 /*
2760 * A utility class that will enumerate over an array of enumerations.
2761 */
2762 final class CompoundEnumeration<E> implements Enumeration<E> {
2763 private final Enumeration<E>[] enums;
2764 private int index;
2765
2766 public CompoundEnumeration(Enumeration<E>[] enums) {
2767 this.enums = enums;
2768 }
2769
2770 private boolean next() {
2771 while (index < enums.length) {
2772 if (enums[index] != null && enums[index].hasMoreElements()) {
2773 return true;
2774 }
2775 index++;
2776 }
2777 return false;
2778 }
2779
2780 public boolean hasMoreElements() {
2781 return next();
2782 }
2783
2784 public E nextElement() {
2785 if (!next()) {
2786 throw new NoSuchElementException();
2787 }
2788 return enums[index].nextElement();
2789 }
2790 }