1 /*
2 * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.io.InputStream;
29 import java.io.IOException;
30 import java.io.UncheckedIOException;
31 import java.io.File;
32 import java.lang.reflect.Constructor;
33 import java.lang.reflect.InvocationTargetException;
34 import java.net.URL;
35 import java.security.AccessController;
36 import java.security.AccessControlContext;
37 import java.security.CodeSource;
38 import java.security.PrivilegedAction;
39 import java.security.ProtectionDomain;
40 import java.security.cert.Certificate;
41 import java.util.ArrayDeque;
42 import java.util.Arrays;
43 import java.util.Collections;
44 import java.util.Deque;
45 import java.util.Enumeration;
46 import java.util.HashMap;
47 import java.util.HashSet;
48 import java.util.Hashtable;
49 import java.util.Map;
50 import java.util.NoSuchElementException;
51 import java.util.Objects;
52 import java.util.Set;
53 import java.util.Spliterator;
54 import java.util.Spliterators;
55 import java.util.Vector;
56 import java.util.WeakHashMap;
57 import java.util.concurrent.ConcurrentHashMap;
58 import java.util.function.Supplier;
59 import java.util.stream.Stream;
60 import java.util.stream.StreamSupport;
61
62 import jdk.internal.perf.PerfCounter;
63 import jdk.internal.loader.BootLoader;
64 import jdk.internal.loader.ClassLoaders;
65 import jdk.internal.misc.Unsafe;
66 import jdk.internal.misc.VM;
67 import jdk.internal.ref.CleanerFactory;
68 import jdk.internal.reflect.CallerSensitive;
69 import jdk.internal.reflect.Reflection;
70 import sun.reflect.misc.ReflectUtil;
71 import sun.security.util.SecurityConstants;
72
73 /**
74 * A class loader is an object that is responsible for loading classes. The
75 * class {@code ClassLoader} is an abstract class. Given the <a
76 * href="#name">binary name</a> of a class, a class loader should attempt to
77 * locate or generate data that constitutes a definition for the class. A
78 * typical strategy is to transform the name into a file name and then read a
79 * "class file" of that name from a file system.
80 *
81 * <p> Every {@link java.lang.Class Class} object contains a {@link
82 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
83 * it.
84 *
85 * <p> {@code Class} objects for array classes are not created by class
86 * loaders, but are created automatically as required by the Java runtime.
87 * The class loader for an array class, as returned by {@link
88 * Class#getClassLoader()} is the same as the class loader for its element
89 * type; if the element type is a primitive type, then the array class has no
90 * class loader.
91 *
92 * <p> Applications implement subclasses of {@code ClassLoader} in order to
93 * extend the manner in which the Java virtual machine dynamically loads
94 * classes.
95 *
96 * <p> Class loaders may typically be used by security managers to indicate
97 * security domains.
98 *
99 * <p> In addition to loading classes, a class loader is also responsible for
100 * locating resources. A resource is some data (a "{@code .class}" file,
101 * configuration data, or an image for example) that is identified with an
102 * abstract '/'-separated path name. Resources are typically packaged with an
103 * application or library so that they can be located by code in the
104 * application or library. In some cases, the resources are included so that
105 * they can be located by other libraries.
106 *
107 * <p> The {@code ClassLoader} class uses a delegation model to search for
108 * classes and resources. Each instance of {@code ClassLoader} has an
109 * associated parent class loader. When requested to find a class or
110 * resource, a {@code ClassLoader} instance will usually delegate the search
111 * for the class or resource to its parent class loader before attempting to
112 * find the class or resource itself.
113 *
114 * <p> Class loaders that support concurrent loading of classes are known as
115 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
116 * loaders and are required to register themselves at their class initialization
117 * time by invoking the {@link
118 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
119 * method. Note that the {@code ClassLoader} class is registered as parallel
120 * capable by default. However, its subclasses still need to register themselves
121 * if they are parallel capable.
122 * In environments in which the delegation model is not strictly
123 * hierarchical, class loaders need to be parallel capable, otherwise class
124 * loading can lead to deadlocks because the loader lock is held for the
125 * duration of the class loading process (see {@link #loadClass
126 * loadClass} methods).
127 *
128 * <h3> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h3>
129 *
130 * The Java run-time has the following built-in class loaders:
131 *
132 * <ul>
133 * <li><p>Bootstrap class loader.
134 * It is the virtual machine's built-in class loader, typically represented
135 * as {@code null}, and does not have a parent.</li>
136 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
137 * All <em>platform classes</em> are visible to the platform class loader
138 * that can be used as the parent of a {@code ClassLoader} instance.
139 * Platform classes include Java SE platform APIs, their implementation
140 * classes and JDK-specific run-time classes that are defined by the
141 * platform class loader or its ancestors.
142 * <p> To allow for upgrading/overriding of modules defined to the platform
143 * class loader, and where upgraded modules read modules defined to class
144 * loaders other than the platform class loader and its ancestors, then
145 * the platform class loader may have to delegate to other class loaders,
146 * the application class loader for example.
147 * In other words, classes in named modules defined to class loaders
148 * other than the platform class loader and its ancestors may be visible
149 * to the platform class loader. </li>
150 * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
151 * It is also known as <em>application class loader</em> and is distinct
152 * from the platform class loader.
153 * The system class loader is typically used to define classes on the
154 * application class path, module path, and JDK-specific tools.
155 * The platform class loader is a parent or an ancestor of the system class
156 * loader that all platform classes are visible to it.</li>
157 * </ul>
158 *
159 * <p> Normally, the Java virtual machine loads classes from the local file
160 * system in a platform-dependent manner.
161 * However, some classes may not originate from a file; they may originate
162 * from other sources, such as the network, or they could be constructed by an
163 * application. The method {@link #defineClass(String, byte[], int, int)
164 * defineClass} converts an array of bytes into an instance of class
165 * {@code Class}. Instances of this newly defined class can be created using
166 * {@link Class#newInstance Class.newInstance}.
167 *
168 * <p> The methods and constructors of objects created by a class loader may
169 * reference other classes. To determine the class(es) referred to, the Java
170 * virtual machine invokes the {@link #loadClass loadClass} method of
171 * the class loader that originally created the class.
172 *
173 * <p> For example, an application could create a network class loader to
174 * download class files from a server. Sample code might look like:
175 *
176 * <blockquote><pre>
177 * ClassLoader loader = new NetworkClassLoader(host, port);
178 * Object main = loader.loadClass("Main", true).newInstance();
179 * . . .
180 * </pre></blockquote>
181 *
182 * <p> The network class loader subclass must define the methods {@link
183 * #findClass findClass} and {@code loadClassData} to load a class
184 * from the network. Once it has downloaded the bytes that make up the class,
185 * it should use the method {@link #defineClass defineClass} to
186 * create a class instance. A sample implementation is:
187 *
188 * <blockquote><pre>
189 * class NetworkClassLoader extends ClassLoader {
190 * String host;
191 * int port;
192 *
193 * public Class findClass(String name) {
194 * byte[] b = loadClassData(name);
195 * return defineClass(name, b, 0, b.length);
196 * }
197 *
198 * private byte[] loadClassData(String name) {
199 * // load the class data from the connection
200 * . . .
201 * }
202 * }
203 * </pre></blockquote>
204 *
205 * <h3> <a id="name">Binary names</a> </h3>
206 *
207 * <p> Any class name provided as a {@code String} parameter to methods in
208 * {@code ClassLoader} must be a binary name as defined by
209 * <cite>The Java™ Language Specification</cite>.
210 *
211 * <p> Examples of valid class names include:
212 * <blockquote><pre>
213 * "java.lang.String"
214 * "javax.swing.JSpinner$DefaultEditor"
215 * "java.security.KeyStore$Builder$FileBuilder$1"
216 * "java.net.URLClassLoader$3$1"
217 * </pre></blockquote>
218 *
219 * <p> Any package name provided as a {@code String} parameter to methods in
220 * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
221 * or a fully qualified name as defined by
222 * <cite>The Java™ Language Specification</cite>.
223 *
224 * @jls 6.7 Fully Qualified Names
225 * @jls 13.1 The Form of a Binary
226 * @see #resolveClass(Class)
227 * @since 1.0
228 * @revised 9
229 * @spec JPMS
230 */
231 public abstract class ClassLoader {
232
233 private static native void registerNatives();
234 static {
235 registerNatives();
236 }
237
238 // The parent class loader for delegation
239 // Note: VM hardcoded the offset of this field, thus all new fields
240 // must be added *after* it.
241 private final ClassLoader parent;
242
243 // class loader name
244 private final String name;
245
246 // the unnamed module for this ClassLoader
247 private final Module unnamedModule;
248
249 /**
250 * Encapsulates the set of parallel capable loader types.
251 */
252 private static class ParallelLoaders {
253 private ParallelLoaders() {}
254
255 // the set of parallel capable loader types
256 private static final Set<Class<? extends ClassLoader>> loaderTypes =
257 Collections.newSetFromMap(new WeakHashMap<>());
258 static {
259 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
260 }
261
262 /**
263 * Registers the given class loader type as parallel capable.
264 * Returns {@code true} is successfully registered; {@code false} if
265 * loader's super class is not registered.
266 */
267 static boolean register(Class<? extends ClassLoader> c) {
268 synchronized (loaderTypes) {
269 if (loaderTypes.contains(c.getSuperclass())) {
270 // register the class loader as parallel capable
271 // if and only if all of its super classes are.
272 // Note: given current classloading sequence, if
273 // the immediate super class is parallel capable,
274 // all the super classes higher up must be too.
275 loaderTypes.add(c);
276 return true;
277 } else {
278 return false;
279 }
280 }
281 }
282
283 /**
284 * Returns {@code true} if the given class loader type is
285 * registered as parallel capable.
286 */
287 static boolean isRegistered(Class<? extends ClassLoader> c) {
288 synchronized (loaderTypes) {
289 return loaderTypes.contains(c);
290 }
291 }
292 }
293
294 // Maps class name to the corresponding lock object when the current
295 // class loader is parallel capable.
296 // Note: VM also uses this field to decide if the current class loader
297 // is parallel capable and the appropriate lock object for class loading.
298 private final ConcurrentHashMap<String, Object> parallelLockMap;
299
300 // Maps packages to certs
301 private final Map <String, Certificate[]> package2certs;
302
303 // Shared among all packages with unsigned classes
304 private static final Certificate[] nocerts = new Certificate[0];
305
306 // The classes loaded by this class loader. The only purpose of this table
307 // is to keep the classes from being GC'ed until the loader is GC'ed.
308 private final Vector<Class<?>> classes = new Vector<>();
309
310 // The "default" domain. Set as the default ProtectionDomain on newly
311 // created classes.
312 private final ProtectionDomain defaultDomain =
313 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
314 null, this, null);
315
316 // Invoked by the VM to record every loaded class with this loader.
317 void addClass(Class<?> c) {
318 classes.addElement(c);
319 }
320
321 // The packages defined in this class loader. Each package name is
322 // mapped to its corresponding NamedPackage object.
323 //
324 // The value is a Package object if ClassLoader::definePackage,
325 // Class::getPackage, ClassLoader::getDefinePackage(s) or
326 // Package::getPackage(s) method is called to define it.
327 // Otherwise, the value is a NamedPackage object.
328 private final ConcurrentHashMap<String, NamedPackage> packages
329 = new ConcurrentHashMap<>();
330
331 /*
332 * Returns a named package for the given module.
333 */
334 private NamedPackage getNamedPackage(String pn, Module m) {
335 NamedPackage p = packages.get(pn);
336 if (p == null) {
337 p = new NamedPackage(pn, m);
338
339 NamedPackage value = packages.putIfAbsent(pn, p);
340 if (value != null) {
341 // Package object already be defined for the named package
342 p = value;
343 // if definePackage is called by this class loader to define
344 // a package in a named module, this will return Package
345 // object of the same name. Package object may contain
346 // unexpected information but it does not impact the runtime.
347 // this assertion may be helpful for troubleshooting
348 assert value.module() == m;
349 }
350 }
351 return p;
352 }
353
354 private static Void checkCreateClassLoader() {
355 return checkCreateClassLoader(null);
356 }
357
358 private static Void checkCreateClassLoader(String name) {
359 if (name != null && name.isEmpty()) {
360 throw new IllegalArgumentException("name must be non-empty or null");
361 }
362
363 SecurityManager security = System.getSecurityManager();
364 if (security != null) {
365 security.checkCreateClassLoader();
366 }
367 return null;
368 }
369
370 private ClassLoader(Void unused, String name, ClassLoader parent) {
371 this.name = name;
372 this.parent = parent;
373 this.unnamedModule = new Module(this);
374 if (ParallelLoaders.isRegistered(this.getClass())) {
375 parallelLockMap = new ConcurrentHashMap<>();
376 package2certs = new ConcurrentHashMap<>();
377 assertionLock = new Object();
378 } else {
379 // no finer-grained lock; lock on the classloader instance
380 parallelLockMap = null;
381 package2certs = new Hashtable<>();
382 assertionLock = this;
383 }
384 }
385
386 /**
387 * Creates a new class loader of the specified name and using the
388 * specified parent class loader for delegation.
389 *
390 * @apiNote If the parent is specified as {@code null} (for the
391 * bootstrap class loader) then there is no guarantee that all platform
392 * classes are visible.
393 *
394 * @param name class loader name; or {@code null} if not named
395 * @param parent the parent class loader
396 *
397 * @throws IllegalArgumentException if the given name is empty.
398 *
399 * @throws SecurityException
400 * If a security manager exists and its
401 * {@link SecurityManager#checkCreateClassLoader()}
402 * method doesn't allow creation of a new class loader.
403 *
404 * @since 9
405 * @spec JPMS
406 */
407 protected ClassLoader(String name, ClassLoader parent) {
408 this(checkCreateClassLoader(name), name, parent);
409 }
410
411 /**
412 * Creates a new class loader using the specified parent class loader for
413 * delegation.
414 *
415 * <p> If there is a security manager, its {@link
416 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
417 * is invoked. This may result in a security exception. </p>
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 parent
424 * The parent class loader
425 *
426 * @throws SecurityException
427 * If a security manager exists and its
428 * {@code checkCreateClassLoader} method doesn't allow creation
429 * of a new class loader.
430 *
431 * @since 1.2
432 */
433 protected ClassLoader(ClassLoader parent) {
434 this(checkCreateClassLoader(), null, parent);
435 }
436
437 /**
438 * Creates a new class loader using the {@code ClassLoader} returned by
439 * the method {@link #getSystemClassLoader()
440 * getSystemClassLoader()} as the parent class loader.
441 *
442 * <p> If there is a security manager, its {@link
443 * SecurityManager#checkCreateClassLoader()
444 * checkCreateClassLoader} method is invoked. This may result in
445 * a security exception. </p>
446 *
447 * @throws SecurityException
448 * If a security manager exists and its
449 * {@code checkCreateClassLoader} method doesn't allow creation
450 * of a new class loader.
451 */
452 protected ClassLoader() {
453 this(checkCreateClassLoader(), null, getSystemClassLoader());
454 }
455
456 /**
457 * Returns the name of this class loader or {@code null} if
458 * this class loader is not named.
459 *
460 * @apiNote This method is non-final for compatibility. If this
461 * method is overridden, this method must return the same name
462 * as specified when this class loader was instantiated.
463 *
464 * @return name of this class loader; or {@code null} if
465 * this class loader is not named.
466 *
467 * @since 9
468 * @spec JPMS
469 */
470 public String getName() {
471 return name;
472 }
473
474 // package-private used by StackTraceElement to avoid
475 // calling the overrideable getName method
476 final String name() {
477 return name;
478 }
479
480 // -- Class --
481
482 /**
483 * Loads the class with the specified <a href="#name">binary name</a>.
484 * This method searches for classes in the same manner as the {@link
485 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
486 * machine to resolve class references. Invoking this method is equivalent
487 * to invoking {@link #loadClass(String, boolean) loadClass(name,
488 * false)}.
489 *
490 * @param name
491 * The <a href="#name">binary name</a> of the class
492 *
493 * @return The resulting {@code Class} object
494 *
495 * @throws ClassNotFoundException
496 * If the class was not found
497 */
498 public Class<?> loadClass(String name) throws ClassNotFoundException {
499 return loadClass(name, false);
500 }
501
502 /**
503 * Loads the class with the specified <a href="#name">binary name</a>. The
504 * default implementation of this method searches for classes in the
505 * following order:
506 *
507 * <ol>
508 *
509 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
510 * has already been loaded. </p></li>
511 *
512 * <li><p> Invoke the {@link #loadClass(String) loadClass} method
513 * on the parent class loader. If the parent is {@code null} the class
514 * loader built into the virtual machine is used, instead. </p></li>
515 *
516 * <li><p> Invoke the {@link #findClass(String)} method to find the
517 * class. </p></li>
518 *
519 * </ol>
520 *
521 * <p> If the class was found using the above steps, and the
522 * {@code resolve} flag is true, this method will then invoke the {@link
523 * #resolveClass(Class)} method on the resulting {@code Class} object.
524 *
525 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
526 * #findClass(String)}, rather than this method. </p>
527 *
528 * <p> Unless overridden, this method synchronizes on the result of
529 * {@link #getClassLoadingLock getClassLoadingLock} method
530 * during the entire class loading process.
531 *
532 * @param name
533 * The <a href="#name">binary name</a> of the class
534 *
535 * @param resolve
536 * If {@code true} then resolve the class
537 *
538 * @return The resulting {@code Class} object
539 *
540 * @throws ClassNotFoundException
541 * If the class could not be found
542 */
543 protected Class<?> loadClass(String name, boolean resolve)
544 throws ClassNotFoundException
545 {
546 synchronized (getClassLoadingLock(name)) {
547 // First, check if the class has already been loaded
548 Class<?> c = findLoadedClass(name);
549 if (c == null) {
550 long t0 = System.nanoTime();
551 try {
552 if (parent != null) {
553 c = parent.loadClass(name, false);
554 } else {
555 c = findBootstrapClassOrNull(name);
556 }
557 } catch (ClassNotFoundException e) {
558 // ClassNotFoundException thrown if class not found
559 // from the non-null parent class loader
560 }
561
562 if (c == null) {
563 // If still not found, then invoke findClass in order
564 // to find the class.
565 long t1 = System.nanoTime();
566 c = findClass(name);
567
568 // this is the defining class loader; record the stats
569 PerfCounter.getParentDelegationTime().addTime(t1 - t0);
570 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
571 PerfCounter.getFindClasses().increment();
572 }
573 }
574 if (resolve) {
575 resolveClass(c);
576 }
577 return c;
578 }
579 }
580
581 /**
582 * Loads the class with the specified <a href="#name">binary name</a>
583 * in a module defined to this class loader. This method returns {@code null}
584 * if the class could not be found.
585 *
586 * @apiNote This method does not delegate to the parent class loader.
587 *
588 * @implSpec The default implementation of this method searches for classes
589 * in the following order:
590 *
591 * <ol>
592 * <li>Invoke {@link #findLoadedClass(String)} to check if the class
593 * has already been loaded.</li>
594 * <li>Invoke the {@link #findClass(String, String)} method to find the
595 * class in the given module.</li>
596 * </ol>
597 *
598 * @param module
599 * The module
600 * @param name
601 * The <a href="#name">binary name</a> of the class
602 *
603 * @return The resulting {@code Class} object in a module defined by
604 * this class loader, or {@code null} if the class could not be found.
605 */
606 final Class<?> loadClass(Module module, String name) {
607 synchronized (getClassLoadingLock(name)) {
608 // First, check if the class has already been loaded
609 Class<?> c = findLoadedClass(name);
610 if (c == null) {
611 c = findClass(module.getName(), name);
612 }
613 if (c != null && c.getModule() == module) {
614 return c;
615 } else {
616 return null;
617 }
618 }
619 }
620
621 /**
622 * Returns the lock object for class loading operations.
623 * For backward compatibility, the default implementation of this method
624 * behaves as follows. If this ClassLoader object is registered as
625 * parallel capable, the method returns a dedicated object associated
626 * with the specified class name. Otherwise, the method returns this
627 * ClassLoader object.
628 *
629 * @param className
630 * The name of the to-be-loaded class
631 *
632 * @return the lock for class loading operations
633 *
634 * @throws NullPointerException
635 * If registered as parallel capable and {@code className} is null
636 *
637 * @see #loadClass(String, boolean)
638 *
639 * @since 1.7
640 */
641 protected Object getClassLoadingLock(String className) {
642 Object lock = this;
643 if (parallelLockMap != null) {
644 Object newLock = new Object();
645 lock = parallelLockMap.putIfAbsent(className, newLock);
646 if (lock == null) {
647 lock = newLock;
648 }
649 }
650 return lock;
651 }
652
653 // Invoked by the VM after loading class with this loader.
654 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
655 final SecurityManager sm = System.getSecurityManager();
656 if (sm != null) {
657 if (ReflectUtil.isNonPublicProxyClass(cls)) {
658 for (Class<?> intf: cls.getInterfaces()) {
659 checkPackageAccess(intf, pd);
660 }
661 return;
662 }
663
664 final String packageName = cls.getPackageName();
665 if (!packageName.isEmpty()) {
666 AccessController.doPrivileged(new PrivilegedAction<>() {
667 public Void run() {
668 sm.checkPackageAccess(packageName);
669 return null;
670 }
671 }, new AccessControlContext(new ProtectionDomain[] {pd}));
672 }
673 }
674 }
675
676 /**
677 * Finds the class with the specified <a href="#name">binary name</a>.
678 * This method should be overridden by class loader implementations that
679 * follow the delegation model for loading classes, and will be invoked by
680 * the {@link #loadClass loadClass} method after checking the
681 * parent class loader for the requested class.
682 *
683 * @implSpec The default implementation throws {@code ClassNotFoundException}.
684 *
685 * @param name
686 * The <a href="#name">binary name</a> of the class
687 *
688 * @return The resulting {@code Class} object
689 *
690 * @throws ClassNotFoundException
691 * If the class could not be found
692 *
693 * @since 1.2
694 */
695 protected Class<?> findClass(String name) throws ClassNotFoundException {
696 throw new ClassNotFoundException(name);
697 }
698
699 /**
700 * Finds the class with the given <a href="#name">binary name</a>
701 * in a module defined to this class loader.
702 * Class loader implementations that support the loading from modules
703 * should override this method.
704 *
705 * @apiNote This method returns {@code null} rather than throwing
706 * {@code ClassNotFoundException} if the class could not be found.
707 *
708 * @implSpec The default implementation attempts to find the class by
709 * invoking {@link #findClass(String)} when the {@code moduleName} is
710 * {@code null}. It otherwise returns {@code null}.
711 *
712 * @param moduleName
713 * The module name; or {@code null} to find the class in the
714 * {@linkplain #getUnnamedModule() unnamed module} for this
715 * class loader
716
717 * @param name
718 * The <a href="#name">binary name</a> of the class
719 *
720 * @return The resulting {@code Class} object, or {@code null}
721 * if the class could not be found.
722 *
723 * @since 9
724 * @spec JPMS
725 */
726 protected Class<?> findClass(String moduleName, String name) {
727 if (moduleName == null) {
728 try {
729 return findClass(name);
730 } catch (ClassNotFoundException ignore) { }
731 }
732 return null;
733 }
734
735
736 /**
737 * Converts an array of bytes into an instance of class {@code Class}.
738 * Before the {@code Class} can be used it must be resolved. This method
739 * is deprecated in favor of the version that takes a <a
740 * href="#name">binary name</a> as its first argument, and is more secure.
741 *
742 * @param b
743 * The bytes that make up the class data. The bytes in positions
744 * {@code off} through {@code off+len-1} should have the format
745 * of a valid class file as defined by
746 * <cite>The Java™ Virtual Machine Specification</cite>.
747 *
748 * @param off
749 * The start offset in {@code b} of the class data
750 *
751 * @param len
752 * The length of the class data
753 *
754 * @return The {@code Class} object that was created from the specified
755 * class data
756 *
757 * @throws ClassFormatError
758 * If the data did not contain a valid class
759 *
760 * @throws IndexOutOfBoundsException
761 * If either {@code off} or {@code len} is negative, or if
762 * {@code off+len} is greater than {@code b.length}.
763 *
764 * @throws SecurityException
765 * If an attempt is made to add this class to a package that
766 * contains classes that were signed by a different set of
767 * certificates than this class, or if an attempt is made
768 * to define a class in a package with a fully-qualified name
769 * that starts with "{@code java.}".
770 *
771 * @see #loadClass(String, boolean)
772 * @see #resolveClass(Class)
773 *
774 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
775 * defineClass(String, byte[], int, int)}
776 */
777 @Deprecated(since="1.1")
778 protected final Class<?> defineClass(byte[] b, int off, int len)
779 throws ClassFormatError
780 {
781 return defineClass(null, b, off, len, null);
782 }
783
784 /**
785 * Converts an array of bytes into an instance of class {@code Class}.
786 * Before the {@code Class} can be used it must be resolved.
787 *
788 * <p> This method assigns a default {@link java.security.ProtectionDomain
789 * ProtectionDomain} to the newly defined class. The
790 * {@code ProtectionDomain} is effectively granted the same set of
791 * permissions returned when {@link
792 * java.security.Policy#getPermissions(java.security.CodeSource)
793 * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
794 * is invoked. The default protection domain is created on the first invocation
795 * of {@link #defineClass(String, byte[], int, int) defineClass},
796 * and re-used on subsequent invocations.
797 *
798 * <p> To assign a specific {@code ProtectionDomain} to the class, use
799 * the {@link #defineClass(String, byte[], int, int,
800 * java.security.ProtectionDomain) defineClass} method that takes a
801 * {@code ProtectionDomain} as one of its arguments. </p>
802 *
803 * <p>
804 * This method defines a package in this class loader corresponding to the
805 * package of the {@code Class} (if such a package has not already been defined
806 * in this class loader). The name of the defined package is derived from
807 * the <a href="#name">binary name</a> of the class specified by
808 * the byte array {@code b}.
809 * Other properties of the defined package are as specified by {@link Package}.
810 *
811 * @param name
812 * The expected <a href="#name">binary name</a> of the class, or
813 * {@code null} if not known
814 *
815 * @param b
816 * The bytes that make up the class data. The bytes in positions
817 * {@code off} through {@code off+len-1} should have the format
818 * of a valid class file as defined by
819 * <cite>The Java™ Virtual Machine Specification</cite>.
820 *
821 * @param off
822 * The start offset in {@code b} of the class data
823 *
824 * @param len
825 * The length of the class data
826 *
827 * @return The {@code Class} object that was created from the specified
828 * class data.
829 *
830 * @throws ClassFormatError
831 * If the data did not contain a valid class
832 *
833 * @throws IndexOutOfBoundsException
834 * If either {@code off} or {@code len} is negative, or if
835 * {@code off+len} is greater than {@code b.length}.
836 *
837 * @throws SecurityException
838 * If an attempt is made to add this class to a package that
839 * contains classes that were signed by a different set of
840 * certificates than this class (which is unsigned), or if
841 * {@code name} begins with "{@code java.}".
842 *
843 * @see #loadClass(String, boolean)
844 * @see #resolveClass(Class)
845 * @see java.security.CodeSource
846 * @see java.security.SecureClassLoader
847 *
848 * @since 1.1
849 * @revised 9
850 * @spec JPMS
851 */
852 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
853 throws ClassFormatError
854 {
855 return defineClass(name, b, off, len, null);
856 }
857
858 /* Determine protection domain, and check that:
859 - not define java.* class,
860 - signer of this class matches signers for the rest of the classes in
861 package.
862 */
863 private ProtectionDomain preDefineClass(String name,
864 ProtectionDomain pd)
865 {
866 if (!checkName(name))
867 throw new NoClassDefFoundError("IllegalName: " + name);
868
869 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
870 // relies on the fact that spoofing is impossible if a class has a name
871 // of the form "java.*"
872 if ((name != null) && name.startsWith("java.")
873 && this != getBuiltinPlatformClassLoader()) {
874 throw new SecurityException
875 ("Prohibited package name: " +
876 name.substring(0, name.lastIndexOf('.')));
877 }
878 if (pd == null) {
879 pd = defaultDomain;
880 }
881
882 if (name != null) {
883 checkCerts(name, pd.getCodeSource());
884 }
885
886 return pd;
887 }
888
889 private String defineClassSourceLocation(ProtectionDomain pd) {
890 CodeSource cs = pd.getCodeSource();
891 String source = null;
892 if (cs != null && cs.getLocation() != null) {
893 source = cs.getLocation().toString();
894 }
895 return source;
896 }
897
898 private void postDefineClass(Class<?> c, ProtectionDomain pd) {
899 // define a named package, if not present
900 getNamedPackage(c.getPackageName(), c.getModule());
901
902 if (pd.getCodeSource() != null) {
903 Certificate certs[] = pd.getCodeSource().getCertificates();
904 if (certs != null)
905 setSigners(c, certs);
906 }
907 }
908
909 /**
910 * Converts an array of bytes into an instance of class {@code Class},
911 * with a given {@code ProtectionDomain}.
912 *
913 * <p> If the given {@code ProtectionDomain} is {@code null},
914 * then a default protection domain will be assigned to the class as specified
915 * in the documentation for {@link #defineClass(String, byte[], int, int)}.
916 * Before the class can be used it must be resolved.
917 *
918 * <p> The first class defined in a package determines the exact set of
919 * certificates that all subsequent classes defined in that package must
920 * contain. The set of certificates for a class is obtained from the
921 * {@link java.security.CodeSource CodeSource} within the
922 * {@code ProtectionDomain} of the class. Any classes added to that
923 * package must contain the same set of certificates or a
924 * {@code SecurityException} will be thrown. Note that if
925 * {@code name} is {@code null}, this check is not performed.
926 * You should always pass in the <a href="#name">binary name</a> of the
927 * class you are defining as well as the bytes. This ensures that the
928 * class you are defining is indeed the class you think it is.
929 *
930 * <p> If the specified {@code name} begins with "{@code java.}", it can
931 * only be defined by the {@linkplain #getPlatformClassLoader()
932 * platform class loader} or its ancestors; otherwise {@code SecurityException}
933 * will be thrown. If {@code name} is not {@code null}, it must be equal to
934 * the <a href="#name">binary name</a> of the class
935 * specified by the byte array {@code b}, otherwise a {@link
936 * NoClassDefFoundError NoClassDefFoundError} will be thrown.
937 *
938 * <p> This method defines a package in this class loader corresponding to the
939 * package of the {@code Class} (if such a package has not already been defined
940 * in this class loader). The name of the defined package is derived from
941 * the <a href="#name">binary name</a> of the class specified by
942 * the byte array {@code b}.
943 * Other properties of the defined package are as specified by {@link Package}.
944 *
945 * @param name
946 * The expected <a href="#name">binary name</a> of the class, or
947 * {@code null} if not known
948 *
949 * @param b
950 * The bytes that make up the class data. The bytes in positions
951 * {@code off} through {@code off+len-1} should have the format
952 * of a valid class file as defined by
953 * <cite>The Java™ Virtual Machine Specification</cite>.
954 *
955 * @param off
956 * The start offset in {@code b} of the class data
957 *
958 * @param len
959 * The length of the class data
960 *
961 * @param protectionDomain
962 * The {@code ProtectionDomain} of the class
963 *
964 * @return The {@code Class} object created from the data,
965 * and {@code ProtectionDomain}.
966 *
967 * @throws ClassFormatError
968 * If the data did not contain a valid class
969 *
970 * @throws NoClassDefFoundError
971 * If {@code name} is not {@code null} and not equal to the
972 * <a href="#name">binary name</a> of the class specified by {@code b}
973 *
974 * @throws IndexOutOfBoundsException
975 * If either {@code off} or {@code len} is negative, or if
976 * {@code off+len} is greater than {@code b.length}.
977 *
978 * @throws SecurityException
979 * If an attempt is made to add this class to a package that
980 * contains classes that were signed by a different set of
981 * certificates than this class, or if {@code name} begins with
982 * "{@code java.}" and this class loader is not the platform
983 * class loader or its ancestor.
984 *
985 * @revised 9
986 * @spec JPMS
987 */
988 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
989 ProtectionDomain protectionDomain)
990 throws ClassFormatError
991 {
992 protectionDomain = preDefineClass(name, protectionDomain);
993 String source = defineClassSourceLocation(protectionDomain);
994 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
995 postDefineClass(c, protectionDomain);
996 return c;
997 }
998
999 /**
1000 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
1001 * of class {@code Class}, with the given {@code ProtectionDomain}.
1002 * If the given {@code ProtectionDomain} is {@code null}, then a default
1003 * protection domain will be assigned to the class as
1004 * specified in the documentation for {@link #defineClass(String, byte[],
1005 * int, int)}. Before the class can be used it must be resolved.
1006 *
1007 * <p>The rules about the first class defined in a package determining the
1008 * set of certificates for the package, the restrictions on class names,
1009 * and the defined package of the class
1010 * are identical to those specified in the documentation for {@link
1011 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
1012 *
1013 * <p> An invocation of this method of the form
1014 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
1015 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
1016 * result as the statements
1017 *
1018 *<p> <code>
1019 * ...<br>
1020 * byte[] temp = new byte[bBuffer.{@link
1021 * java.nio.ByteBuffer#remaining remaining}()];<br>
1022 * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
1023 * get}(temp);<br>
1024 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
1025 * cl.defineClass}(name, temp, 0,
1026 * temp.length, pd);<br>
1027 * </code></p>
1028 *
1029 * @param name
1030 * The expected <a href="#name">binary name</a>. of the class, or
1031 * {@code null} if not known
1032 *
1033 * @param b
1034 * The bytes that make up the class data. The bytes from positions
1035 * {@code b.position()} through {@code b.position() + b.limit() -1
1036 * } should have the format of a valid class file as defined by
1037 * <cite>The Java™ Virtual Machine Specification</cite>.
1038 *
1039 * @param protectionDomain
1040 * The {@code ProtectionDomain} of the class, or {@code null}.
1041 *
1042 * @return The {@code Class} object created from the data,
1043 * and {@code ProtectionDomain}.
1044 *
1045 * @throws ClassFormatError
1046 * If the data did not contain a valid class.
1047 *
1048 * @throws NoClassDefFoundError
1049 * If {@code name} is not {@code null} and not equal to the
1050 * <a href="#name">binary name</a> of the class specified by {@code b}
1051 *
1052 * @throws SecurityException
1053 * If an attempt is made to add this class to a package that
1054 * contains classes that were signed by a different set of
1055 * certificates than this class, or if {@code name} begins with
1056 * "{@code java.}".
1057 *
1058 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
1059 *
1060 * @since 1.5
1061 * @revised 9
1062 * @spec JPMS
1063 */
1064 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
1065 ProtectionDomain protectionDomain)
1066 throws ClassFormatError
1067 {
1068 int len = b.remaining();
1069
1070 // Use byte[] if not a direct ByteBuffer:
1071 if (!b.isDirect()) {
1072 if (b.hasArray()) {
1073 return defineClass(name, b.array(),
1074 b.position() + b.arrayOffset(), len,
1075 protectionDomain);
1076 } else {
1077 // no array, or read-only array
1078 byte[] tb = new byte[len];
1079 b.get(tb); // get bytes out of byte buffer.
1080 return defineClass(name, tb, 0, len, protectionDomain);
1081 }
1082 }
1083
1084 protectionDomain = preDefineClass(name, protectionDomain);
1085 String source = defineClassSourceLocation(protectionDomain);
1086 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
1087 postDefineClass(c, protectionDomain);
1088 return c;
1089 }
1090
1091 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
1092 ProtectionDomain pd, String source);
1093
1094 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
1095 int off, int len, ProtectionDomain pd,
1096 String source);
1097
1098 // true if the name is null or has the potential to be a valid binary name
1099 private boolean checkName(String name) {
1100 if ((name == null) || (name.length() == 0))
1101 return true;
1102 if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
1103 return false;
1104 return true;
1105 }
1106
1107 private void checkCerts(String name, CodeSource cs) {
1108 int i = name.lastIndexOf('.');
1109 String pname = (i == -1) ? "" : name.substring(0, i);
1110
1111 Certificate[] certs = null;
1112 if (cs != null) {
1113 certs = cs.getCertificates();
1114 }
1115 Certificate[] pcerts = null;
1116 if (parallelLockMap == null) {
1117 synchronized (this) {
1118 pcerts = package2certs.get(pname);
1119 if (pcerts == null) {
1120 package2certs.put(pname, (certs == null? nocerts:certs));
1121 }
1122 }
1123 } else {
1124 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
1125 putIfAbsent(pname, (certs == null? nocerts:certs));
1126 }
1127 if (pcerts != null && !compareCerts(pcerts, certs)) {
1128 throw new SecurityException("class \"" + name
1129 + "\"'s signer information does not match signer information"
1130 + " of other classes in the same package");
1131 }
1132 }
1133
1134 /**
1135 * check to make sure the certs for the new class (certs) are the same as
1136 * the certs for the first class inserted in the package (pcerts)
1137 */
1138 private boolean compareCerts(Certificate[] pcerts,
1139 Certificate[] certs)
1140 {
1141 // certs can be null, indicating no certs.
1142 if ((certs == null) || (certs.length == 0)) {
1143 return pcerts.length == 0;
1144 }
1145
1146 // the length must be the same at this point
1147 if (certs.length != pcerts.length)
1148 return false;
1149
1150 // go through and make sure all the certs in one array
1151 // are in the other and vice-versa.
1152 boolean match;
1153 for (Certificate cert : certs) {
1154 match = false;
1155 for (Certificate pcert : pcerts) {
1156 if (cert.equals(pcert)) {
1157 match = true;
1158 break;
1159 }
1160 }
1161 if (!match) return false;
1162 }
1163
1164 // now do the same for pcerts
1165 for (Certificate pcert : pcerts) {
1166 match = false;
1167 for (Certificate cert : certs) {
1168 if (pcert.equals(cert)) {
1169 match = true;
1170 break;
1171 }
1172 }
1173 if (!match) return false;
1174 }
1175
1176 return true;
1177 }
1178
1179 /**
1180 * Links the specified class. This (misleadingly named) method may be
1181 * used by a class loader to link a class. If the class {@code c} has
1182 * already been linked, then this method simply returns. Otherwise, the
1183 * class is linked as described in the "Execution" chapter of
1184 * <cite>The Java™ Language Specification</cite>.
1185 *
1186 * @param c
1187 * The class to link
1188 *
1189 * @throws NullPointerException
1190 * If {@code c} is {@code null}.
1191 *
1192 * @see #defineClass(String, byte[], int, int)
1193 */
1194 protected final void resolveClass(Class<?> c) {
1195 if (c == null) {
1196 throw new NullPointerException();
1197 }
1198 }
1199
1200 /**
1201 * Finds a class with the specified <a href="#name">binary name</a>,
1202 * loading it if necessary.
1203 *
1204 * <p> This method loads the class through the system class loader (see
1205 * {@link #getSystemClassLoader()}). The {@code Class} object returned
1206 * might have more than one {@code ClassLoader} associated with it.
1207 * Subclasses of {@code ClassLoader} need not usually invoke this method,
1208 * because most class loaders need to override just {@link
1209 * #findClass(String)}. </p>
1210 *
1211 * @param name
1212 * The <a href="#name">binary name</a> of the class
1213 *
1214 * @return The {@code Class} object for the specified {@code name}
1215 *
1216 * @throws ClassNotFoundException
1217 * If the class could not be found
1218 *
1219 * @see #ClassLoader(ClassLoader)
1220 * @see #getParent()
1221 */
1222 protected final Class<?> findSystemClass(String name)
1223 throws ClassNotFoundException
1224 {
1225 return getSystemClassLoader().loadClass(name);
1226 }
1227
1228 /**
1229 * Returns a class loaded by the bootstrap class loader;
1230 * or return null if not found.
1231 */
1232 Class<?> findBootstrapClassOrNull(String name) {
1233 if (!checkName(name)) return null;
1234
1235 return findBootstrapClass(name);
1236 }
1237
1238 // return null if not found
1239 private native Class<?> findBootstrapClass(String name);
1240
1241 /**
1242 * Returns the class with the given <a href="#name">binary name</a> if this
1243 * loader has been recorded by the Java virtual machine as an initiating
1244 * loader of a class with that <a href="#name">binary name</a>. Otherwise
1245 * {@code null} is returned.
1246 *
1247 * @param name
1248 * The <a href="#name">binary name</a> of the class
1249 *
1250 * @return The {@code Class} object, or {@code null} if the class has
1251 * not been loaded
1252 *
1253 * @since 1.1
1254 */
1255 protected final Class<?> findLoadedClass(String name) {
1256 if (!checkName(name))
1257 return null;
1258 return findLoadedClass0(name);
1259 }
1260
1261 private final native Class<?> findLoadedClass0(String name);
1262
1263 /**
1264 * Sets the signers of a class. This should be invoked after defining a
1265 * class.
1266 *
1267 * @param c
1268 * The {@code Class} object
1269 *
1270 * @param signers
1271 * The signers for the class
1272 *
1273 * @since 1.1
1274 */
1275 protected final void setSigners(Class<?> c, Object[] signers) {
1276 c.setSigners(signers);
1277 }
1278
1279
1280 // -- Resources --
1281
1282 /**
1283 * Returns a URL to a resource in a module defined to this class loader.
1284 * Class loader implementations that support the loading from modules
1285 * should override this method.
1286 *
1287 * @apiNote This method is the basis for the {@link
1288 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
1289 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
1290 * Module.getResourceAsStream} methods. It is not subject to the rules for
1291 * encapsulation specified by {@code Module.getResourceAsStream}.
1292 *
1293 * @implSpec The default implementation attempts to find the resource by
1294 * invoking {@link #findResource(String)} when the {@code moduleName} is
1295 * {@code null}. It otherwise returns {@code null}.
1296 *
1297 * @param moduleName
1298 * The module name; or {@code null} to find a resource in the
1299 * {@linkplain #getUnnamedModule() unnamed module} for this
1300 * class loader
1301 * @param name
1302 * The resource name
1303 *
1304 * @return A URL to the resource; {@code null} if the resource could not be
1305 * found, a URL could not be constructed to locate the resource,
1306 * access to the resource is denied by the security manager, or
1307 * there isn't a module of the given name defined to the class
1308 * loader.
1309 *
1310 * @throws IOException
1311 * If I/O errors occur
1312 *
1313 * @see java.lang.module.ModuleReader#find(String)
1314 * @since 9
1315 * @spec JPMS
1316 */
1317 protected URL findResource(String moduleName, String name) throws IOException {
1318 if (moduleName == null) {
1319 return findResource(name);
1320 } else {
1321 return null;
1322 }
1323 }
1324
1325 /**
1326 * Finds the resource with the given name. A resource is some data
1327 * (images, audio, text, etc) that can be accessed by class code in a way
1328 * that is independent of the location of the code.
1329 *
1330 * <p> The name of a resource is a '{@code /}'-separated path name that
1331 * identifies the resource. </p>
1332 *
1333 * <p> Resources in named modules are subject to the encapsulation rules
1334 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1335 * Additionally, and except for the special case where the resource has a
1336 * name ending with "{@code .class}", this method will only find resources in
1337 * packages of named modules when the package is {@link Module#isOpen(String)
1338 * opened} unconditionally (even if the caller of this method is in the
1339 * same module as the resource). </p>
1340 *
1341 * @implSpec The default implementation will first search the parent class
1342 * loader for the resource; if the parent is {@code null} the path of the
1343 * class loader built into the virtual machine is searched. If not found,
1344 * this method will invoke {@link #findResource(String)} to find the resource.
1345 *
1346 * @apiNote Where several modules are defined to the same class loader,
1347 * and where more than one module contains a resource with the given name,
1348 * then the ordering that modules are searched is not specified and may be
1349 * very unpredictable.
1350 * When overriding this method it is recommended that an implementation
1351 * ensures that any delegation is consistent with the {@link
1352 * #getResources(java.lang.String) getResources(String)} method.
1353 *
1354 * @param name
1355 * The resource name
1356 *
1357 * @return {@code URL} object for reading the resource; {@code null} if
1358 * the resource could not be found, a {@code URL} could not be
1359 * constructed to locate the resource, the resource is in a package
1360 * that is not opened unconditionally, or access to the resource is
1361 * denied by the security manager.
1362 *
1363 * @throws NullPointerException If {@code name} is {@code null}
1364 *
1365 * @since 1.1
1366 * @revised 9
1367 * @spec JPMS
1368 */
1369 public URL getResource(String name) {
1370 Objects.requireNonNull(name);
1371 URL url;
1372 if (parent != null) {
1373 url = parent.getResource(name);
1374 } else {
1375 url = BootLoader.findResource(name);
1376 }
1377 if (url == null) {
1378 url = findResource(name);
1379 }
1380 return url;
1381 }
1382
1383 /**
1384 * Finds all the resources with the given name. A resource is some data
1385 * (images, audio, text, etc) that can be accessed by class code in a way
1386 * that is independent of the location of the code.
1387 *
1388 * <p> The name of a resource is a {@code /}-separated path name that
1389 * identifies the resource. </p>
1390 *
1391 * <p> Resources in named modules are subject to the encapsulation rules
1392 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1393 * Additionally, and except for the special case where the resource has a
1394 * name ending with "{@code .class}", this method will only find resources in
1395 * packages of named modules when the package is {@link Module#isOpen(String)
1396 * opened} unconditionally (even if the caller of this method is in the
1397 * same module as the resource). </p>
1398 *
1399 * @implSpec The default implementation will first search the parent class
1400 * loader for the resource; if the parent is {@code null} the path of the
1401 * class loader built into the virtual machine is searched. It then
1402 * invokes {@link #findResources(String)} to find the resources with the
1403 * name in this class loader. It returns an enumeration whose elements
1404 * are the URLs found by searching the parent class loader followed by
1405 * the elements found with {@code findResources}.
1406 *
1407 * @apiNote Where several modules are defined to the same class loader,
1408 * and where more than one module contains a resource with the given name,
1409 * then the ordering is not specified and may be very unpredictable.
1410 * When overriding this method it is recommended that an
1411 * implementation ensures that any delegation is consistent with the {@link
1412 * #getResource(java.lang.String) getResource(String)} method. This should
1413 * ensure that the first element returned by the Enumeration's
1414 * {@code nextElement} method is the same resource that the
1415 * {@code getResource(String)} method would return.
1416 *
1417 * @param name
1418 * The resource name
1419 *
1420 * @return An enumeration of {@link java.net.URL URL} objects for
1421 * the resource. If no resources could be found, the enumeration
1422 * will be empty. Resources for which a {@code URL} cannot be
1423 * constructed, are in package that is not opened unconditionally,
1424 * or access to the resource is denied by the security manager,
1425 * are not returned in the enumeration.
1426 *
1427 * @throws IOException
1428 * If I/O errors occur
1429 * @throws NullPointerException If {@code name} is {@code null}
1430 *
1431 * @since 1.2
1432 * @revised 9
1433 * @spec JPMS
1434 */
1435 public Enumeration<URL> getResources(String name) throws IOException {
1436 Objects.requireNonNull(name);
1437 @SuppressWarnings("unchecked")
1438 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1439 if (parent != null) {
1440 tmp[0] = parent.getResources(name);
1441 } else {
1442 tmp[0] = BootLoader.findResources(name);
1443 }
1444 tmp[1] = findResources(name);
1445
1446 return new CompoundEnumeration<>(tmp);
1447 }
1448
1449 /**
1450 * Returns a stream whose elements are the URLs of all the resources with
1451 * the given name. A resource is some data (images, audio, text, etc) that
1452 * can be accessed by class code in a way that is independent of the
1453 * location of the code.
1454 *
1455 * <p> The name of a resource is a {@code /}-separated path name that
1456 * identifies the resource.
1457 *
1458 * <p> The resources will be located when the returned stream is evaluated.
1459 * If the evaluation results in an {@code IOException} then the I/O
1460 * exception is wrapped in an {@link UncheckedIOException} that is then
1461 * thrown.
1462 *
1463 * <p> Resources in named modules are subject to the encapsulation rules
1464 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1465 * Additionally, and except for the special case where the resource has a
1466 * name ending with "{@code .class}", this method will only find resources in
1467 * packages of named modules when the package is {@link Module#isOpen(String)
1468 * opened} unconditionally (even if the caller of this method is in the
1469 * same module as the resource). </p>
1470 *
1471 * @implSpec The default implementation invokes {@link #getResources(String)
1472 * getResources} to find all the resources with the given name and returns
1473 * a stream with the elements in the enumeration as the source.
1474 *
1475 * @apiNote When overriding this method it is recommended that an
1476 * implementation ensures that any delegation is consistent with the {@link
1477 * #getResource(java.lang.String) getResource(String)} method. This should
1478 * ensure that the first element returned by the stream is the same
1479 * resource that the {@code getResource(String)} method would return.
1480 *
1481 * @param name
1482 * The resource name
1483 *
1484 * @return A stream of resource {@link java.net.URL URL} objects. If no
1485 * resources could be found, the stream will be empty. Resources
1486 * for which a {@code URL} cannot be constructed, are in a package
1487 * that is not opened unconditionally, or access to the resource
1488 * is denied by the security manager, will not be in the stream.
1489 *
1490 * @throws NullPointerException If {@code name} is {@code null}
1491 *
1492 * @since 9
1493 */
1494 public Stream<URL> resources(String name) {
1495 Objects.requireNonNull(name);
1496 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
1497 Supplier<Spliterator<URL>> si = () -> {
1498 try {
1499 return Spliterators.spliteratorUnknownSize(
1500 getResources(name).asIterator(), characteristics);
1501 } catch (IOException e) {
1502 throw new UncheckedIOException(e);
1503 }
1504 };
1505 return StreamSupport.stream(si, characteristics, false);
1506 }
1507
1508 /**
1509 * Finds the resource with the given name. Class loader implementations
1510 * should override this method.
1511 *
1512 * <p> For resources in named modules then the method must implement the
1513 * rules for encapsulation specified in the {@code Module} {@link
1514 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1515 * it must not find non-"{@code .class}" resources in packages of named
1516 * modules unless the package is {@link Module#isOpen(String) opened}
1517 * unconditionally. </p>
1518 *
1519 * @implSpec The default implementation returns {@code null}.
1520 *
1521 * @param name
1522 * The resource name
1523 *
1524 * @return {@code URL} object for reading the resource; {@code null} if
1525 * the resource could not be found, a {@code URL} could not be
1526 * constructed to locate the resource, the resource is in a package
1527 * that is not opened unconditionally, or access to the resource is
1528 * denied by the security manager.
1529 *
1530 * @since 1.2
1531 * @revised 9
1532 * @spec JPMS
1533 */
1534 protected URL findResource(String name) {
1535 return null;
1536 }
1537
1538 /**
1539 * Returns an enumeration of {@link java.net.URL URL} objects
1540 * representing all the resources with the given name. Class loader
1541 * implementations should override this method.
1542 *
1543 * <p> For resources in named modules then the method must implement the
1544 * rules for encapsulation specified in the {@code Module} {@link
1545 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1546 * it must not find non-"{@code .class}" resources in packages of named
1547 * modules unless the package is {@link Module#isOpen(String) opened}
1548 * unconditionally. </p>
1549 *
1550 * @implSpec The default implementation returns an enumeration that
1551 * contains no elements.
1552 *
1553 * @param name
1554 * The resource name
1555 *
1556 * @return An enumeration of {@link java.net.URL URL} objects for
1557 * the resource. If no resources could be found, the enumeration
1558 * will be empty. Resources for which a {@code URL} cannot be
1559 * constructed, are in a package that is not opened unconditionally,
1560 * or access to the resource is denied by the security manager,
1561 * are not returned in the enumeration.
1562 *
1563 * @throws IOException
1564 * If I/O errors occur
1565 *
1566 * @since 1.2
1567 * @revised 9
1568 * @spec JPMS
1569 */
1570 protected Enumeration<URL> findResources(String name) throws IOException {
1571 return Collections.emptyEnumeration();
1572 }
1573
1574 /**
1575 * Registers the caller as
1576 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
1577 * The registration succeeds if and only if all of the following
1578 * conditions are met:
1579 * <ol>
1580 * <li> no instance of the caller has been created</li>
1581 * <li> all of the super classes (except class Object) of the caller are
1582 * registered as parallel capable</li>
1583 * </ol>
1584 * <p>Note that once a class loader is registered as parallel capable, there
1585 * is no way to change it back.</p>
1586 *
1587 * @return {@code true} if the caller is successfully registered as
1588 * parallel capable and {@code false} if otherwise.
1589 *
1590 * @see #isRegisteredAsParallelCapable()
1591 *
1592 * @since 1.7
1593 */
1594 @CallerSensitive
1595 protected static boolean registerAsParallelCapable() {
1596 Class<? extends ClassLoader> callerClass =
1597 Reflection.getCallerClass().asSubclass(ClassLoader.class);
1598 return ParallelLoaders.register(callerClass);
1599 }
1600
1601 /**
1602 * Returns {@code true} if this class loader is registered as
1603 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
1604 * {@code false}.
1605 *
1606 * @return {@code true} if this class loader is parallel capable,
1607 * otherwise {@code false}.
1608 *
1609 * @see #registerAsParallelCapable()
1610 *
1611 * @since 9
1612 */
1613 public final boolean isRegisteredAsParallelCapable() {
1614 return ParallelLoaders.isRegistered(this.getClass());
1615 }
1616
1617 /**
1618 * Find a resource of the specified name from the search path used to load
1619 * classes. This method locates the resource through the system class
1620 * loader (see {@link #getSystemClassLoader()}).
1621 *
1622 * <p> Resources in named modules are subject to the encapsulation rules
1623 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1624 * Additionally, and except for the special case where the resource has a
1625 * name ending with "{@code .class}", this method will only find resources in
1626 * packages of named modules when the package is {@link Module#isOpen(String)
1627 * opened} unconditionally. </p>
1628 *
1629 * @param name
1630 * The resource name
1631 *
1632 * @return A {@link java.net.URL URL} to the resource; {@code
1633 * null} if the resource could not be found, a URL could not be
1634 * constructed to locate the resource, the resource is in a package
1635 * that is not opened unconditionally or access to the resource is
1636 * denied by the security manager.
1637 *
1638 * @since 1.1
1639 * @revised 9
1640 * @spec JPMS
1641 */
1642 public static URL getSystemResource(String name) {
1643 return getSystemClassLoader().getResource(name);
1644 }
1645
1646 /**
1647 * Finds all resources of the specified name from the search path used to
1648 * load classes. The resources thus found are returned as an
1649 * {@link java.util.Enumeration Enumeration} of {@link
1650 * java.net.URL URL} objects.
1651 *
1652 * <p> The search order is described in the documentation for {@link
1653 * #getSystemResource(String)}. </p>
1654 *
1655 * <p> Resources in named modules are subject to the encapsulation rules
1656 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1657 * Additionally, and except for the special case where the resource has a
1658 * name ending with "{@code .class}", this method will only find resources in
1659 * packages of named modules when the package is {@link Module#isOpen(String)
1660 * opened} unconditionally. </p>
1661 *
1662 * @param name
1663 * The resource name
1664 *
1665 * @return An enumeration of {@link java.net.URL URL} objects for
1666 * the resource. If no resources could be found, the enumeration
1667 * will be empty. Resources for which a {@code URL} cannot be
1668 * constructed, are in a package that is not opened unconditionally,
1669 * or access to the resource is denied by the security manager,
1670 * are not returned in the enumeration.
1671 *
1672 * @throws IOException
1673 * If I/O errors occur
1674 *
1675 * @since 1.2
1676 * @revised 9
1677 * @spec JPMS
1678 */
1679 public static Enumeration<URL> getSystemResources(String name)
1680 throws IOException
1681 {
1682 return getSystemClassLoader().getResources(name);
1683 }
1684
1685 /**
1686 * Returns an input stream for reading the specified resource.
1687 *
1688 * <p> The search order is described in the documentation for {@link
1689 * #getResource(String)}. </p>
1690 *
1691 * <p> Resources in named modules are subject to the encapsulation rules
1692 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1693 * Additionally, and except for the special case where the resource has a
1694 * name ending with "{@code .class}", this method will only find resources in
1695 * packages of named modules when the package is {@link Module#isOpen(String)
1696 * opened} unconditionally. </p>
1697 *
1698 * @param name
1699 * The resource name
1700 *
1701 * @return An input stream for reading the resource; {@code null} if the
1702 * resource could not be found, the resource is in a package that
1703 * is not opened unconditionally, or access to the resource is
1704 * denied by the security manager.
1705 *
1706 * @throws NullPointerException If {@code name} is {@code null}
1707 *
1708 * @since 1.1
1709 * @revised 9
1710 * @spec JPMS
1711 */
1712 public InputStream getResourceAsStream(String name) {
1713 Objects.requireNonNull(name);
1714 URL url = getResource(name);
1715 try {
1716 return url != null ? url.openStream() : null;
1717 } catch (IOException e) {
1718 return null;
1719 }
1720 }
1721
1722 /**
1723 * Open for reading, a resource of the specified name from the search path
1724 * used to load classes. This method locates the resource through the
1725 * system class loader (see {@link #getSystemClassLoader()}).
1726 *
1727 * <p> Resources in named modules are subject to the encapsulation rules
1728 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1729 * Additionally, and except for the special case where the resource has a
1730 * name ending with "{@code .class}", this method will only find resources in
1731 * packages of named modules when the package is {@link Module#isOpen(String)
1732 * opened} unconditionally. </p>
1733 *
1734 * @param name
1735 * The resource name
1736 *
1737 * @return An input stream for reading the resource; {@code null} if the
1738 * resource could not be found, the resource is in a package that
1739 * is not opened unconditionally, or access to the resource is
1740 * denied by the security manager.
1741 *
1742 * @since 1.1
1743 * @revised 9
1744 * @spec JPMS
1745 */
1746 public static InputStream getSystemResourceAsStream(String name) {
1747 URL url = getSystemResource(name);
1748 try {
1749 return url != null ? url.openStream() : null;
1750 } catch (IOException e) {
1751 return null;
1752 }
1753 }
1754
1755
1756 // -- Hierarchy --
1757
1758 /**
1759 * Returns the parent class loader for delegation. Some implementations may
1760 * use {@code null} to represent the bootstrap class loader. This method
1761 * will return {@code null} in such implementations if this class loader's
1762 * parent is the bootstrap class loader.
1763 *
1764 * @return The parent {@code ClassLoader}
1765 *
1766 * @throws SecurityException
1767 * If a security manager is present, and the caller's class loader
1768 * is not {@code null} and is not an ancestor of this class loader,
1769 * and the caller does not have the
1770 * {@link RuntimePermission}{@code ("getClassLoader")}
1771 *
1772 * @since 1.2
1773 */
1774 @CallerSensitive
1775 public final ClassLoader getParent() {
1776 if (parent == null)
1777 return null;
1778 SecurityManager sm = System.getSecurityManager();
1779 if (sm != null) {
1780 // Check access to the parent class loader
1781 // If the caller's class loader is same as this class loader,
1782 // permission check is performed.
1783 checkClassLoaderPermission(parent, Reflection.getCallerClass());
1784 }
1785 return parent;
1786 }
1787
1788 /**
1789 * Returns the unnamed {@code Module} for this class loader.
1790 *
1791 * @return The unnamed Module for this class loader
1792 *
1793 * @see Module#isNamed()
1794 * @since 9
1795 * @spec JPMS
1796 */
1797 public final Module getUnnamedModule() {
1798 return unnamedModule;
1799 }
1800
1801 /**
1802 * Returns the platform class loader. All
1803 * <a href="#builtinLoaders">platform classes</a> are visible to
1804 * the platform class loader.
1805 *
1806 * @implNote The name of the builtin platform class loader is
1807 * {@code "platform"}.
1808 *
1809 * @return The platform {@code ClassLoader}.
1810 *
1811 * @throws SecurityException
1812 * If a security manager is present, and the caller's class loader is
1813 * not {@code null}, and the caller's class loader is not the same
1814 * as or an ancestor of the platform class loader,
1815 * and the caller does not have the
1816 * {@link RuntimePermission}{@code ("getClassLoader")}
1817 *
1818 * @since 9
1819 * @spec JPMS
1820 */
1821 @CallerSensitive
1822 public static ClassLoader getPlatformClassLoader() {
1823 SecurityManager sm = System.getSecurityManager();
1824 ClassLoader loader = getBuiltinPlatformClassLoader();
1825 if (sm != null) {
1826 checkClassLoaderPermission(loader, Reflection.getCallerClass());
1827 }
1828 return loader;
1829 }
1830
1831 /**
1832 * Returns the system class loader. This is the default
1833 * delegation parent for new {@code ClassLoader} instances, and is
1834 * typically the class loader used to start the application.
1835 *
1836 * <p> This method is first invoked early in the runtime's startup
1837 * sequence, at which point it creates the system class loader. This
1838 * class loader will be the context class loader for the main application
1839 * thread (for example, the thread that invokes the {@code main} method of
1840 * the main class).
1841 *
1842 * <p> The default system class loader is an implementation-dependent
1843 * instance of this class.
1844 *
1845 * <p> If the system property "{@code java.system.class.loader}" is defined
1846 * when this method is first invoked then the value of that property is
1847 * taken to be the name of a class that will be returned as the system
1848 * class loader. The class is loaded using the default system class loader
1849 * and must define a public constructor that takes a single parameter of
1850 * type {@code ClassLoader} which is used as the delegation parent. An
1851 * instance is then created using this constructor with the default system
1852 * class loader as the parameter. The resulting class loader is defined
1853 * to be the system class loader. During construction, the class loader
1854 * should take great care to avoid calling {@code getSystemClassLoader()}.
1855 * If circular initialization of the system class loader is detected then
1856 * an {@code IllegalStateException} is thrown.
1857 *
1858 * @implNote The system property to override the system class loader is not
1859 * examined until the VM is almost fully initialized. Code that executes
1860 * this method during startup should take care not to cache the return
1861 * value until the system is fully initialized.
1862 *
1863 * <p> The name of the built-in system class loader is {@code "app"}.
1864 * The system property "{@code java.class.path}" is read during early
1865 * initialization of the VM to determine the class path.
1866 * An empty value of "{@code java.class.path}" property is interpreted
1867 * differently depending on whether the initial module (the module
1868 * containing the main class) is named or unnamed:
1869 * If named, the built-in system class loader will have no class path and
1870 * will search for classes and resources using the application module path;
1871 * otherwise, if unnamed, it will set the class path to the current
1872 * working directory.
1873 *
1874 * @return The system {@code ClassLoader}
1875 *
1876 * @throws SecurityException
1877 * If a security manager is present, and the caller's class loader
1878 * is not {@code null} and is not the same as or an ancestor of the
1879 * system class loader, and the caller does not have the
1880 * {@link RuntimePermission}{@code ("getClassLoader")}
1881 *
1882 * @throws IllegalStateException
1883 * If invoked recursively during the construction of the class
1884 * loader specified by the "{@code java.system.class.loader}"
1885 * property.
1886 *
1887 * @throws Error
1888 * If the system property "{@code java.system.class.loader}"
1889 * is defined but the named class could not be loaded, the
1890 * provider class does not define the required constructor, or an
1891 * exception is thrown by that constructor when it is invoked. The
1892 * underlying cause of the error can be retrieved via the
1893 * {@link Throwable#getCause()} method.
1894 *
1895 * @revised 1.4
1896 * @revised 9
1897 * @spec JPMS
1898 */
1899 @CallerSensitive
1900 public static ClassLoader getSystemClassLoader() {
1901 switch (VM.initLevel()) {
1902 case 0:
1903 case 1:
1904 case 2:
1905 // the system class loader is the built-in app class loader during startup
1906 return getBuiltinAppClassLoader();
1907 case 3:
1908 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
1909 throw new IllegalStateException(msg);
1910 default:
1911 // system fully initialized
1912 assert VM.isBooted() && scl != null;
1913 SecurityManager sm = System.getSecurityManager();
1914 if (sm != null) {
1915 checkClassLoaderPermission(scl, Reflection.getCallerClass());
1916 }
1917 return scl;
1918 }
1919 }
1920
1921 static ClassLoader getBuiltinPlatformClassLoader() {
1922 return ClassLoaders.platformClassLoader();
1923 }
1924
1925 static ClassLoader getBuiltinAppClassLoader() {
1926 return ClassLoaders.appClassLoader();
1927 }
1928
1929 /*
1930 * Initialize the system class loader that may be a custom class on the
1931 * application class path or application module path.
1932 *
1933 * @see java.lang.System#initPhase3
1934 */
1935 static synchronized ClassLoader initSystemClassLoader() {
1936 if (VM.initLevel() != 3) {
1937 throw new InternalError("system class loader cannot be set at initLevel " +
1938 VM.initLevel());
1939 }
1940
1941 // detect recursive initialization
1942 if (scl != null) {
1943 throw new IllegalStateException("recursive invocation");
1944 }
1945
1946 ClassLoader builtinLoader = getBuiltinAppClassLoader();
1947
1948 // All are privileged frames. No need to call doPrivileged.
1949 String cn = System.getProperty("java.system.class.loader");
1950 if (cn != null) {
1951 try {
1952 // custom class loader is only supported to be loaded from unnamed module
1953 Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
1954 .getDeclaredConstructor(ClassLoader.class);
1955 scl = (ClassLoader) ctor.newInstance(builtinLoader);
1956 } catch (Exception e) {
1957 Throwable cause = e;
1958 if (e instanceof InvocationTargetException) {
1959 cause = e.getCause();
1960 if (cause instanceof Error) {
1961 throw (Error) cause;
1962 }
1963 }
1964 if (cause instanceof RuntimeException) {
1965 throw (RuntimeException) cause;
1966 }
1967 throw new Error(cause.getMessage(), cause);
1968 }
1969 } else {
1970 scl = builtinLoader;
1971 }
1972 return scl;
1973 }
1974
1975 // Returns true if the specified class loader can be found in this class
1976 // loader's delegation chain.
1977 boolean isAncestor(ClassLoader cl) {
1978 ClassLoader acl = this;
1979 do {
1980 acl = acl.parent;
1981 if (cl == acl) {
1982 return true;
1983 }
1984 } while (acl != null);
1985 return false;
1986 }
1987
1988 // Tests if class loader access requires "getClassLoader" permission
1989 // check. A class loader 'from' can access class loader 'to' if
1990 // class loader 'from' is same as class loader 'to' or an ancestor
1991 // of 'to'. The class loader in a system domain can access
1992 // any class loader.
1993 private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
1994 ClassLoader to)
1995 {
1996 if (from == to)
1997 return false;
1998
1999 if (from == null)
2000 return false;
2001
2002 return !to.isAncestor(from);
2003 }
2004
2005 // Returns the class's class loader, or null if none.
2006 static ClassLoader getClassLoader(Class<?> caller) {
2007 // This can be null if the VM is requesting it
2008 if (caller == null) {
2009 return null;
2010 }
2011 // Circumvent security check since this is package-private
2012 return caller.getClassLoader0();
2013 }
2014
2015 /*
2016 * Checks RuntimePermission("getClassLoader") permission
2017 * if caller's class loader is not null and caller's class loader
2018 * is not the same as or an ancestor of the given cl argument.
2019 */
2020 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
2021 SecurityManager sm = System.getSecurityManager();
2022 if (sm != null) {
2023 // caller can be null if the VM is requesting it
2024 ClassLoader ccl = getClassLoader(caller);
2025 if (needsClassLoaderPermissionCheck(ccl, cl)) {
2026 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
2027 }
2028 }
2029 }
2030
2031 // The system class loader
2032 // @GuardedBy("ClassLoader.class")
2033 private static volatile ClassLoader scl;
2034
2035 // -- Package --
2036
2037 /**
2038 * Define a Package of the given Class object.
2039 *
2040 * If the given class represents an array type, a primitive type or void,
2041 * this method returns {@code null}.
2042 *
2043 * This method does not throw IllegalArgumentException.
2044 */
2045 Package definePackage(Class<?> c) {
2046 if (c.isPrimitive() || c.isArray()) {
2047 return null;
2048 }
2049
2050 return definePackage(c.getPackageName(), c.getModule());
2051 }
2052
2053 /**
2054 * Defines a Package of the given name and module
2055 *
2056 * This method does not throw IllegalArgumentException.
2057 *
2058 * @param name package name
2059 * @param m module
2060 */
2061 Package definePackage(String name, Module m) {
2062 if (name.isEmpty() && m.isNamed()) {
2063 throw new InternalError("unnamed package in " + m);
2064 }
2065
2066 // check if Package object is already defined
2067 NamedPackage pkg = packages.get(name);
2068 if (pkg instanceof Package)
2069 return (Package)pkg;
2070
2071 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
2072 }
2073
2074 /*
2075 * Returns a Package object for the named package
2076 */
2077 private Package toPackage(String name, NamedPackage p, Module m) {
2078 // define Package object if the named package is not yet defined
2079 if (p == null)
2080 return NamedPackage.toPackage(name, m);
2081
2082 // otherwise, replace the NamedPackage object with Package object
2083 if (p instanceof Package)
2084 return (Package)p;
2085
2086 return NamedPackage.toPackage(p.packageName(), p.module());
2087 }
2088
2089 /**
2090 * Defines a package by <a href="#name">name</a> in this {@code ClassLoader}.
2091 * <p>
2092 * <a href="#name">Package names</a> must be unique within a class loader and
2093 * cannot be redefined or changed once created.
2094 * <p>
2095 * If a class loader wishes to define a package with specific properties,
2096 * such as version information, then the class loader should call this
2097 * {@code definePackage} method before calling {@code defineClass}.
2098 * Otherwise, the
2099 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
2100 * method will define a package in this class loader corresponding to the package
2101 * of the newly defined class; the properties of this defined package are
2102 * specified by {@link Package}.
2103 *
2104 * @apiNote
2105 * A class loader that wishes to define a package for classes in a JAR
2106 * typically uses the specification and implementation titles, versions, and
2107 * vendors from the JAR's manifest. If the package is specified as
2108 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
2109 * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
2110 * If classes of package {@code 'p'} defined by this class loader
2111 * are loaded from multiple JARs, the {@code Package} object may contain
2112 * different information depending on the first class of package {@code 'p'}
2113 * defined and which JAR's manifest is read first to explicitly define
2114 * package {@code 'p'}.
2115 *
2116 * <p> It is strongly recommended that a class loader does not call this
2117 * method to explicitly define packages in <em>named modules</em>; instead,
2118 * the package will be automatically defined when a class is {@linkplain
2119 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
2120 * If it is desirable to define {@code Package} explicitly, it should ensure
2121 * that all packages in a named module are defined with the properties
2122 * specified by {@link Package}. Otherwise, some {@code Package} objects
2123 * in a named module may be for example sealed with different seal base.
2124 *
2125 * @param name
2126 * The <a href="#name">package name</a>
2127 *
2128 * @param specTitle
2129 * The specification title
2130 *
2131 * @param specVersion
2132 * The specification version
2133 *
2134 * @param specVendor
2135 * The specification vendor
2136 *
2137 * @param implTitle
2138 * The implementation title
2139 *
2140 * @param implVersion
2141 * The implementation version
2142 *
2143 * @param implVendor
2144 * The implementation vendor
2145 *
2146 * @param sealBase
2147 * If not {@code null}, then this package is sealed with
2148 * respect to the given code source {@link java.net.URL URL}
2149 * object. Otherwise, the package is not sealed.
2150 *
2151 * @return The newly defined {@code Package} object
2152 *
2153 * @throws NullPointerException
2154 * if {@code name} is {@code null}.
2155 *
2156 * @throws IllegalArgumentException
2157 * if a package of the given {@code name} is already
2158 * defined by this class loader
2159 *
2160 *
2161 * @since 1.2
2162 * @revised 9
2163 * @spec JPMS
2164 *
2165 * @jvms 5.3 Run-time package
2166 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
2167 * The JAR File Specification: Package Sealing</a>
2168 */
2169 protected Package definePackage(String name, String specTitle,
2170 String specVersion, String specVendor,
2171 String implTitle, String implVersion,
2172 String implVendor, URL sealBase)
2173 {
2174 Objects.requireNonNull(name);
2175
2176 // definePackage is not final and may be overridden by custom class loader
2177 Package p = new Package(name, specTitle, specVersion, specVendor,
2178 implTitle, implVersion, implVendor,
2179 sealBase, this);
2180
2181 if (packages.putIfAbsent(name, p) != null)
2182 throw new IllegalArgumentException(name);
2183
2184 return p;
2185 }
2186
2187 /**
2188 * Returns a {@code Package} of the given <a href="#name">name</a> that
2189 * has been defined by this class loader.
2190 *
2191 * @param name The <a href="#name">package name</a>
2192 *
2193 * @return The {@code Package} of the given name that has been defined
2194 * by this class loader, or {@code null} if not found
2195 *
2196 * @throws NullPointerException
2197 * if {@code name} is {@code null}.
2198 *
2199 * @jvms 5.3 Run-time package
2200 *
2201 * @since 9
2202 * @spec JPMS
2203 */
2204 public final Package getDefinedPackage(String name) {
2205 Objects.requireNonNull(name, "name cannot be null");
2206
2207 NamedPackage p = packages.get(name);
2208 if (p == null)
2209 return null;
2210
2211 return definePackage(name, p.module());
2212 }
2213
2214 /**
2215 * Returns all of the {@code Package}s that have been defined by
2216 * this class loader. The returned array has no duplicated {@code Package}s
2217 * of the same name.
2218 *
2219 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
2220 * for consistency with the existing {@link #getPackages} method.
2221 *
2222 * @return The array of {@code Package} objects that have been defined by
2223 * this class loader; or an zero length array if no package has been
2224 * defined by this class loader.
2225 *
2226 * @jvms 5.3 Run-time package
2227 *
2228 * @since 9
2229 * @spec JPMS
2230 */
2231 public final Package[] getDefinedPackages() {
2232 return packages().toArray(Package[]::new);
2233 }
2234
2235 /**
2236 * Finds a package by <a href="#name">name</a> in this class loader and its ancestors.
2237 * <p>
2238 * If this class loader defines a {@code Package} of the given name,
2239 * the {@code Package} is returned. Otherwise, the ancestors of
2240 * this class loader are searched recursively (parent by parent)
2241 * for a {@code Package} of the given name.
2242 *
2243 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2244 * may delegate to the application class loader but the application class
2245 * loader is not its ancestor. When invoked on the platform class loader,
2246 * this method will not find packages defined to the application
2247 * class loader.
2248 *
2249 * @param name
2250 * The <a href="#name">package name</a>
2251 *
2252 * @return The {@code Package} of the given name that has been defined by
2253 * this class loader or its ancestors, or {@code null} if not found.
2254 *
2255 * @throws NullPointerException
2256 * if {@code name} is {@code null}.
2257 *
2258 * @deprecated
2259 * If multiple class loaders delegate to each other and define classes
2260 * with the same package name, and one such loader relies on the lookup
2261 * behavior of {@code getPackage} to return a {@code Package} from
2262 * a parent loader, then the properties exposed by the {@code Package}
2263 * may not be as expected in the rest of the program.
2264 * For example, the {@code Package} will only expose annotations from the
2265 * {@code package-info.class} file defined by the parent loader, even if
2266 * annotations exist in a {@code package-info.class} file defined by
2267 * a child loader. A more robust approach is to use the
2268 * {@link ClassLoader#getDefinedPackage} method which returns
2269 * a {@code Package} for the specified class loader.
2270 *
2271 * @see ClassLoader#getDefinedPackage(String)
2272 *
2273 * @since 1.2
2274 * @revised 9
2275 * @spec JPMS
2276 */
2277 @Deprecated(since="9")
2278 protected Package getPackage(String name) {
2279 Package pkg = getDefinedPackage(name);
2280 if (pkg == null) {
2281 if (parent != null) {
2282 pkg = parent.getPackage(name);
2283 } else {
2284 pkg = BootLoader.getDefinedPackage(name);
2285 }
2286 }
2287 return pkg;
2288 }
2289
2290 /**
2291 * Returns all of the {@code Package}s that have been defined by
2292 * this class loader and its ancestors. The returned array may contain
2293 * more than one {@code Package} object of the same package name, each
2294 * defined by a different class loader in the class loader hierarchy.
2295 *
2296 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2297 * may delegate to the application class loader. In other words,
2298 * packages in modules defined to the application class loader may be
2299 * visible to the platform class loader. On the other hand,
2300 * the application class loader is not its ancestor and hence
2301 * when invoked on the platform class loader, this method will not
2302 * return any packages defined to the application class loader.
2303 *
2304 * @return The array of {@code Package} objects that have been defined by
2305 * this class loader and its ancestors
2306 *
2307 * @see ClassLoader#getDefinedPackages()
2308 *
2309 * @since 1.2
2310 * @revised 9
2311 * @spec JPMS
2312 */
2313 protected Package[] getPackages() {
2314 Stream<Package> pkgs = packages();
2315 ClassLoader ld = parent;
2316 while (ld != null) {
2317 pkgs = Stream.concat(ld.packages(), pkgs);
2318 ld = ld.parent;
2319 }
2320 return Stream.concat(BootLoader.packages(), pkgs)
2321 .toArray(Package[]::new);
2322 }
2323
2324
2325
2326 // package-private
2327
2328 /**
2329 * Returns a stream of Packages defined in this class loader
2330 */
2331 Stream<Package> packages() {
2332 return packages.values().stream()
2333 .map(p -> definePackage(p.packageName(), p.module()));
2334 }
2335
2336 // -- Native library access --
2337
2338 /**
2339 * Returns the absolute path name of a native library. The VM invokes this
2340 * method to locate the native libraries that belong to classes loaded with
2341 * this class loader. If this method returns {@code null}, the VM
2342 * searches the library along the path specified as the
2343 * "{@code java.library.path}" property.
2344 *
2345 * @param libname
2346 * The library name
2347 *
2348 * @return The absolute path of the native library
2349 *
2350 * @see System#loadLibrary(String)
2351 * @see System#mapLibraryName(String)
2352 *
2353 * @since 1.2
2354 */
2355 protected String findLibrary(String libname) {
2356 return null;
2357 }
2358
2359 /**
2360 * The inner class NativeLibrary denotes a loaded native library instance.
2361 * Every classloader contains a vector of loaded native libraries in the
2362 * private field {@code nativeLibraries}. The native libraries loaded
2363 * into the system are entered into the {@code systemNativeLibraries}
2364 * vector.
2365 *
2366 * <p> Every native library requires a particular version of JNI. This is
2367 * denoted by the private {@code jniVersion} field. This field is set by
2368 * the VM when it loads the library, and used by the VM to pass the correct
2369 * version of JNI to the native methods. </p>
2370 *
2371 * @see ClassLoader
2372 * @since 1.2
2373 */
2374 static class NativeLibrary {
2375 // the class from which the library is loaded, also indicates
2376 // the loader this native library belongs.
2377 final Class<?> fromClass;
2378 // the canonicalized name of the native library.
2379 // or static library name
2380 final String name;
2381 // Indicates if the native library is linked into the VM
2382 final boolean isBuiltin;
2383
2384 // opaque handle to native library, used in native code.
2385 long handle;
2386 // the version of JNI environment the native library requires.
2387 int jniVersion;
2388
2389 native boolean load0(String name, boolean isBuiltin);
2390
2391 native long findEntry(String name);
2392
2393 NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
2394 this.name = name;
2395 this.fromClass = fromClass;
2396 this.isBuiltin = isBuiltin;
2397 }
2398
2399 /*
2400 * Loads the native library and registers for cleanup when its
2401 * associated class loader is unloaded
2402 */
2403 boolean load() {
2404 if (handle != 0) {
2405 throw new InternalError("Native library " + name + " has been loaded");
2406 }
2407
2408 if (!load0(name, isBuiltin)) return false;
2409
2410 // register the class loader for cleanup when unloaded
2411 // built class loaders are never unloaded
2412 ClassLoader loader = fromClass.getClassLoader();
2413 if (loader != null &&
2414 loader != getBuiltinPlatformClassLoader() &&
2415 loader != getBuiltinAppClassLoader()) {
2416 CleanerFactory.cleaner().register(loader,
2417 new Unloader(name, handle, isBuiltin));
2418 }
2419 return true;
2420 }
2421
2422 static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
2423 ClassLoader loader =
2424 fromClass == null ? null : fromClass.getClassLoader();
2425
2426 synchronized (loadedLibraryNames) {
2427 Map<String, NativeLibrary> libs =
2428 loader != null ? loader.nativeLibraries() : systemNativeLibraries();
2429 if (libs.containsKey(name)) {
2430 return true;
2431 }
2432
2433 if (loadedLibraryNames.contains(name)) {
2434 throw new UnsatisfiedLinkError("Native Library " + name +
2435 " already loaded in another classloader");
2436 }
2437
2438 /*
2439 * When a library is being loaded, JNI_OnLoad function can cause
2440 * another loadLibrary invocation that should succeed.
2441 *
2442 * We use a static stack to hold the list of libraries we are
2443 * loading because this can happen only when called by the
2444 * same thread because Runtime.load and Runtime.loadLibrary
2445 * are synchronous.
2446 *
2447 * If there is a pending load operation for the library, we
2448 * immediately return success; otherwise, we raise
2449 * UnsatisfiedLinkError.
2450 */
2451 for (NativeLibrary lib : nativeLibraryContext) {
2452 if (name.equals(lib.name)) {
2453 if (loader == lib.fromClass.getClassLoader()) {
2454 return true;
2455 } else {
2456 throw new UnsatisfiedLinkError("Native Library " +
2457 name + " is being loaded in another classloader");
2458 }
2459 }
2460 }
2461 NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
2462 // load the native library
2463 nativeLibraryContext.push(lib);
2464 try {
2465 if (!lib.load()) return false;
2466 } finally {
2467 nativeLibraryContext.pop();
2468 }
2469 // register the loaded native library
2470 loadedLibraryNames.add(name);
2471 libs.put(name, lib);
2472 }
2473 return true;
2474 }
2475
2476 // Invoked in the VM to determine the context class in JNI_OnLoad
2477 // and JNI_OnUnload
2478 static Class<?> getFromClass() {
2479 return nativeLibraryContext.peek().fromClass;
2480 }
2481
2482 // native libraries being loaded
2483 static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8);
2484
2485 /*
2486 * The run() method will be invoked when this class loader becomes
2487 * phantom reachable to unload the native library.
2488 */
2489 static class Unloader implements Runnable {
2490 // This represents the context when a native library is unloaded
2491 // and getFromClass() will return null,
2492 static final NativeLibrary UNLOADER =
2493 new NativeLibrary(null, "dummy", false);
2494 final String name;
2495 final long handle;
2496 final boolean isBuiltin;
2497
2498 Unloader(String name, long handle, boolean isBuiltin) {
2499 if (handle == 0) {
2500 throw new IllegalArgumentException(
2501 "Invalid handle for native library " + name);
2502 }
2503
2504 this.name = name;
2505 this.handle = handle;
2506 this.isBuiltin = isBuiltin;
2507 }
2508
2509 @Override
2510 public void run() {
2511 synchronized (loadedLibraryNames) {
2512 /* remove the native library name */
2513 loadedLibraryNames.remove(name);
2514 nativeLibraryContext.push(UNLOADER);
2515 try {
2516 unload(name, isBuiltin, handle);
2517 } finally {
2518 nativeLibraryContext.pop();
2519 }
2520
2521 }
2522 }
2523 }
2524
2525 // JNI FindClass expects the caller class if invoked from JNI_OnLoad
2526 // and JNI_OnUnload is NativeLibrary class
2527 static native void unload(String name, boolean isBuiltin, long handle);
2528 }
2529
2530 // The paths searched for libraries
2531 private static String usr_paths[];
2532 private static String sys_paths[];
2533
2534 private static String[] initializePath(String propName) {
2535 String ldPath = System.getProperty(propName, "");
2536 int ldLen = ldPath.length();
2537 char ps = File.pathSeparatorChar;
2538 int psCount = 0;
2539
2540 if (ClassLoaderHelper.allowsQuotedPathElements &&
2541 ldPath.indexOf('\"') >= 0) {
2542 // First, remove quotes put around quoted parts of paths.
2543 // Second, use a quotation mark as a new path separator.
2544 // This will preserve any quoted old path separators.
2545 char[] buf = new char[ldLen];
2546 int bufLen = 0;
2547 for (int i = 0; i < ldLen; ++i) {
2548 char ch = ldPath.charAt(i);
2549 if (ch == '\"') {
2550 while (++i < ldLen &&
2551 (ch = ldPath.charAt(i)) != '\"') {
2552 buf[bufLen++] = ch;
2553 }
2554 } else {
2555 if (ch == ps) {
2556 psCount++;
2557 ch = '\"';
2558 }
2559 buf[bufLen++] = ch;
2560 }
2561 }
2562 ldPath = new String(buf, 0, bufLen);
2563 ldLen = bufLen;
2564 ps = '\"';
2565 } else {
2566 for (int i = ldPath.indexOf(ps); i >= 0;
2567 i = ldPath.indexOf(ps, i + 1)) {
2568 psCount++;
2569 }
2570 }
2571
2572 String[] paths = new String[psCount + 1];
2573 int pathStart = 0;
2574 for (int j = 0; j < psCount; ++j) {
2575 int pathEnd = ldPath.indexOf(ps, pathStart);
2576 paths[j] = (pathStart < pathEnd) ?
2577 ldPath.substring(pathStart, pathEnd) : ".";
2578 pathStart = pathEnd + 1;
2579 }
2580 paths[psCount] = (pathStart < ldLen) ?
2581 ldPath.substring(pathStart, ldLen) : ".";
2582 return paths;
2583 }
2584
2585 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
2586 static void loadLibrary(Class<?> fromClass, String name,
2587 boolean isAbsolute) {
2588 ClassLoader loader =
2589 (fromClass == null) ? null : fromClass.getClassLoader();
2590 if (sys_paths == null) {
2591 usr_paths = initializePath("java.library.path");
2592 sys_paths = initializePath("sun.boot.library.path");
2593 }
2594 if (isAbsolute) {
2595 if (loadLibrary0(fromClass, new File(name))) {
2596 return;
2597 }
2598 throw new UnsatisfiedLinkError("Can't load library: " + name);
2599 }
2600 if (loader != null) {
2601 String libfilename = loader.findLibrary(name);
2602 if (libfilename != null) {
2603 File libfile = new File(libfilename);
2604 if (!libfile.isAbsolute()) {
2605 throw new UnsatisfiedLinkError(
2606 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
2607 }
2608 if (loadLibrary0(fromClass, libfile)) {
2609 return;
2610 }
2611 throw new UnsatisfiedLinkError("Can't load " + libfilename);
2612 }
2613 }
2614 for (String sys_path : sys_paths) {
2615 File libfile = new File(sys_path, System.mapLibraryName(name));
2616 if (loadLibrary0(fromClass, libfile)) {
2617 return;
2618 }
2619 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
2620 if (libfile != null && loadLibrary0(fromClass, libfile)) {
2621 return;
2622 }
2623 }
2624 if (loader != null) {
2625 for (String usr_path : usr_paths) {
2626 File libfile = new File(usr_path, System.mapLibraryName(name));
2627 if (loadLibrary0(fromClass, libfile)) {
2628 return;
2629 }
2630 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
2631 if (libfile != null && loadLibrary0(fromClass, libfile)) {
2632 return;
2633 }
2634 }
2635 }
2636 // Oops, it failed
2637 throw new UnsatisfiedLinkError("no " + name +
2638 " in java.library.path: " + Arrays.toString(usr_paths));
2639 }
2640
2641 private static native String findBuiltinLib(String name);
2642
2643 private static boolean loadLibrary0(Class<?> fromClass, final File file) {
2644 // Check to see if we're attempting to access a static library
2645 String name = findBuiltinLib(file.getName());
2646 boolean isBuiltin = (name != null);
2647 if (!isBuiltin) {
2648 name = AccessController.doPrivileged(
2649 new PrivilegedAction<>() {
2650 public String run() {
2651 try {
2652 return file.exists() ? file.getCanonicalPath() : null;
2653 } catch (IOException e) {
2654 return null;
2655 }
2656 }
2657 });
2658 if (name == null) {
2659 return false;
2660 }
2661 }
2662 return NativeLibrary.loadLibrary(fromClass, name, isBuiltin);
2663 }
2664
2665 /*
2666 * Invoked in the VM class linking code.
2667 */
2668 private static long findNative(ClassLoader loader, String entryName) {
2669 Map<String, NativeLibrary> libs =
2670 loader != null ? loader.nativeLibraries() : systemNativeLibraries();
2671 if (libs.isEmpty())
2672 return 0;
2673
2674 // the native libraries map may be updated in another thread
2675 // when a native library is being loaded. No symbol will be
2676 // searched from it yet.
2677 for (NativeLibrary lib : libs.values()) {
2678 long entry = lib.findEntry(entryName);
2679 if (entry != 0) return entry;
2680 }
2681 return 0;
2682 }
2683
2684 // All native library names we've loaded.
2685 // This also serves as the lock to obtain nativeLibraries
2686 // and write to nativeLibraryContext.
2687 private static final Set<String> loadedLibraryNames = new HashSet<>();
2688
2689 // Native libraries belonging to system classes.
2690 private static volatile Map<String, NativeLibrary> systemNativeLibraries;
2691
2692 // Native libraries associated with the class loader.
2693 private volatile Map<String, NativeLibrary> nativeLibraries;
2694
2695 /*
2696 * Returns the native libraries map associated with bootstrap class loader
2697 * This method will create the map at the first time when called.
2698 */
2699 private static Map<String, NativeLibrary> systemNativeLibraries() {
2700 Map<String, NativeLibrary> libs = systemNativeLibraries;
2701 if (libs == null) {
2702 synchronized (loadedLibraryNames) {
2703 libs = systemNativeLibraries;
2704 if (libs == null) {
2705 libs = systemNativeLibraries = new ConcurrentHashMap<>();
2706 }
2707 }
2708 }
2709 return libs;
2710 }
2711
2712 /*
2713 * Returns the native libraries map associated with this class loader
2714 * This method will create the map at the first time when called.
2715 */
2716 private Map<String, NativeLibrary> nativeLibraries() {
2717 Map<String, NativeLibrary> libs = nativeLibraries;
2718 if (libs == null) {
2719 synchronized (loadedLibraryNames) {
2720 libs = nativeLibraries;
2721 if (libs == null) {
2722 libs = nativeLibraries = new ConcurrentHashMap<>();
2723 }
2724 }
2725 }
2726 return libs;
2727 }
2728
2729 // -- Assertion management --
2730
2731 final Object assertionLock;
2732
2733 // The default toggle for assertion checking.
2734 // @GuardedBy("assertionLock")
2735 private boolean defaultAssertionStatus = false;
2736
2737 // Maps String packageName to Boolean package default assertion status Note
2738 // that the default package is placed under a null map key. If this field
2739 // is null then we are delegating assertion status queries to the VM, i.e.,
2740 // none of this ClassLoader's assertion status modification methods have
2741 // been invoked.
2742 // @GuardedBy("assertionLock")
2743 private Map<String, Boolean> packageAssertionStatus = null;
2744
2745 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
2746 // field is null then we are delegating assertion status queries to the VM,
2747 // i.e., none of this ClassLoader's assertion status modification methods
2748 // have been invoked.
2749 // @GuardedBy("assertionLock")
2750 Map<String, Boolean> classAssertionStatus = null;
2751
2752 /**
2753 * Sets the default assertion status for this class loader. This setting
2754 * determines whether classes loaded by this class loader and initialized
2755 * in the future will have assertions enabled or disabled by default.
2756 * This setting may be overridden on a per-package or per-class basis by
2757 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
2758 * #setClassAssertionStatus(String, boolean)}.
2759 *
2760 * @param enabled
2761 * {@code true} if classes loaded by this class loader will
2762 * henceforth have assertions enabled by default, {@code false}
2763 * if they will have assertions disabled by default.
2764 *
2765 * @since 1.4
2766 */
2767 public void setDefaultAssertionStatus(boolean enabled) {
2768 synchronized (assertionLock) {
2769 if (classAssertionStatus == null)
2770 initializeJavaAssertionMaps();
2771
2772 defaultAssertionStatus = enabled;
2773 }
2774 }
2775
2776 /**
2777 * Sets the package default assertion status for the named package. The
2778 * package default assertion status determines the assertion status for
2779 * classes initialized in the future that belong to the named package or
2780 * any of its "subpackages".
2781 *
2782 * <p> A subpackage of a package named p is any package whose name begins
2783 * with "{@code p.}". For example, {@code javax.swing.text} is a
2784 * subpackage of {@code javax.swing}, and both {@code java.util} and
2785 * {@code java.lang.reflect} are subpackages of {@code java}.
2786 *
2787 * <p> In the event that multiple package defaults apply to a given class,
2788 * the package default pertaining to the most specific package takes
2789 * precedence over the others. For example, if {@code javax.lang} and
2790 * {@code javax.lang.reflect} both have package defaults associated with
2791 * them, the latter package default applies to classes in
2792 * {@code javax.lang.reflect}.
2793 *
2794 * <p> Package defaults take precedence over the class loader's default
2795 * assertion status, and may be overridden on a per-class basis by invoking
2796 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2797 *
2798 * @param packageName
2799 * The name of the package whose package default assertion status
2800 * is to be set. A {@code null} value indicates the unnamed
2801 * package that is "current"
2802 * (see section 7.4.2 of
2803 * <cite>The Java™ Language Specification</cite>.)
2804 *
2805 * @param enabled
2806 * {@code true} if classes loaded by this classloader and
2807 * belonging to the named package or any of its subpackages will
2808 * have assertions enabled by default, {@code false} if they will
2809 * have assertions disabled by default.
2810 *
2811 * @since 1.4
2812 */
2813 public void setPackageAssertionStatus(String packageName,
2814 boolean enabled) {
2815 synchronized (assertionLock) {
2816 if (packageAssertionStatus == null)
2817 initializeJavaAssertionMaps();
2818
2819 packageAssertionStatus.put(packageName, enabled);
2820 }
2821 }
2822
2823 /**
2824 * Sets the desired assertion status for the named top-level class in this
2825 * class loader and any nested classes contained therein. This setting
2826 * takes precedence over the class loader's default assertion status, and
2827 * over any applicable per-package default. This method has no effect if
2828 * the named class has already been initialized. (Once a class is
2829 * initialized, its assertion status cannot change.)
2830 *
2831 * <p> If the named class is not a top-level class, this invocation will
2832 * have no effect on the actual assertion status of any class. </p>
2833 *
2834 * @param className
2835 * The fully qualified class name of the top-level class whose
2836 * assertion status is to be set.
2837 *
2838 * @param enabled
2839 * {@code true} if the named class is to have assertions
2840 * enabled when (and if) it is initialized, {@code false} if the
2841 * class is to have assertions disabled.
2842 *
2843 * @since 1.4
2844 */
2845 public void setClassAssertionStatus(String className, boolean enabled) {
2846 synchronized (assertionLock) {
2847 if (classAssertionStatus == null)
2848 initializeJavaAssertionMaps();
2849
2850 classAssertionStatus.put(className, enabled);
2851 }
2852 }
2853
2854 /**
2855 * Sets the default assertion status for this class loader to
2856 * {@code false} and discards any package defaults or class assertion
2857 * status settings associated with the class loader. This method is
2858 * provided so that class loaders can be made to ignore any command line or
2859 * persistent assertion status settings and "start with a clean slate."
2860 *
2861 * @since 1.4
2862 */
2863 public void clearAssertionStatus() {
2864 /*
2865 * Whether or not "Java assertion maps" are initialized, set
2866 * them to empty maps, effectively ignoring any present settings.
2867 */
2868 synchronized (assertionLock) {
2869 classAssertionStatus = new HashMap<>();
2870 packageAssertionStatus = new HashMap<>();
2871 defaultAssertionStatus = false;
2872 }
2873 }
2874
2875 /**
2876 * Returns the assertion status that would be assigned to the specified
2877 * class if it were to be initialized at the time this method is invoked.
2878 * If the named class has had its assertion status set, the most recent
2879 * setting will be returned; otherwise, if any package default assertion
2880 * status pertains to this class, the most recent setting for the most
2881 * specific pertinent package default assertion status is returned;
2882 * otherwise, this class loader's default assertion status is returned.
2883 * </p>
2884 *
2885 * @param className
2886 * The fully qualified class name of the class whose desired
2887 * assertion status is being queried.
2888 *
2889 * @return The desired assertion status of the specified class.
2890 *
2891 * @see #setClassAssertionStatus(String, boolean)
2892 * @see #setPackageAssertionStatus(String, boolean)
2893 * @see #setDefaultAssertionStatus(boolean)
2894 *
2895 * @since 1.4
2896 */
2897 boolean desiredAssertionStatus(String className) {
2898 synchronized (assertionLock) {
2899 // assert classAssertionStatus != null;
2900 // assert packageAssertionStatus != null;
2901
2902 // Check for a class entry
2903 Boolean result = classAssertionStatus.get(className);
2904 if (result != null)
2905 return result.booleanValue();
2906
2907 // Check for most specific package entry
2908 int dotIndex = className.lastIndexOf('.');
2909 if (dotIndex < 0) { // default package
2910 result = packageAssertionStatus.get(null);
2911 if (result != null)
2912 return result.booleanValue();
2913 }
2914 while(dotIndex > 0) {
2915 className = className.substring(0, dotIndex);
2916 result = packageAssertionStatus.get(className);
2917 if (result != null)
2918 return result.booleanValue();
2919 dotIndex = className.lastIndexOf('.', dotIndex-1);
2920 }
2921
2922 // Return the classloader default
2923 return defaultAssertionStatus;
2924 }
2925 }
2926
2927 // Set up the assertions with information provided by the VM.
2928 // Note: Should only be called inside a synchronized block
2929 private void initializeJavaAssertionMaps() {
2930 // assert Thread.holdsLock(assertionLock);
2931
2932 classAssertionStatus = new HashMap<>();
2933 packageAssertionStatus = new HashMap<>();
2934 AssertionStatusDirectives directives = retrieveDirectives();
2935
2936 for(int i = 0; i < directives.classes.length; i++)
2937 classAssertionStatus.put(directives.classes[i],
2938 directives.classEnabled[i]);
2939
2940 for(int i = 0; i < directives.packages.length; i++)
2941 packageAssertionStatus.put(directives.packages[i],
2942 directives.packageEnabled[i]);
2943
2944 defaultAssertionStatus = directives.deflt;
2945 }
2946
2947 // Retrieves the assertion directives from the VM.
2948 private static native AssertionStatusDirectives retrieveDirectives();
2949
2950
2951 // -- Misc --
2952
2953 /**
2954 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
2955 * associated with this ClassLoader, creating it if it doesn't already exist.
2956 */
2957 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
2958 ConcurrentHashMap<?, ?> map = classLoaderValueMap;
2959 if (map == null) {
2960 map = new ConcurrentHashMap<>();
2961 boolean set = trySetObjectField("classLoaderValueMap", map);
2962 if (!set) {
2963 // beaten by someone else
2964 map = classLoaderValueMap;
2965 }
2966 }
2967 return map;
2968 }
2969
2970 // the storage for ClassLoaderValue(s) associated with this ClassLoader
2971 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
2972
2973 /**
2974 * Attempts to atomically set a volatile field in this object. Returns
2975 * {@code true} if not beaten by another thread. Avoids the use of
2976 * AtomicReferenceFieldUpdater in this class.
2977 */
2978 private boolean trySetObjectField(String name, Object obj) {
2979 Unsafe unsafe = Unsafe.getUnsafe();
2980 Class<?> k = ClassLoader.class;
2981 long offset;
2982 offset = unsafe.objectFieldOffset(k, name);
2983 return unsafe.compareAndSetObject(this, offset, null, obj);
2984 }
2985 }
2986
2987 /*
2988 * A utility class that will enumerate over an array of enumerations.
2989 */
2990 final class CompoundEnumeration<E> implements Enumeration<E> {
2991 private final Enumeration<E>[] enums;
2992 private int index;
2993
2994 public CompoundEnumeration(Enumeration<E>[] enums) {
2995 this.enums = enums;
2996 }
2997
2998 private boolean next() {
2999 while (index < enums.length) {
3000 if (enums[index] != null && enums[index].hasMoreElements()) {
3001 return true;
3002 }
3003 index++;
3004 }
3005 return false;
3006 }
3007
3008 public boolean hasMoreElements() {
3009 return next();
3010 }
3011
3012 public E nextElement() {
3013 if (!next()) {
3014 throw new NoSuchElementException();
3015 }
3016 return enums[index].nextElement();
3017 }
3018 }