1 /*
2 * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2019, Azul Systems, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 */
26
27 package java.lang;
28
29 import java.io.InputStream;
30 import java.io.IOException;
31 import java.io.UncheckedIOException;
32 import java.io.File;
33 import java.lang.reflect.Constructor;
34 import java.lang.reflect.InvocationTargetException;
35 import java.net.URL;
36 import java.security.AccessController;
37 import java.security.AccessControlContext;
38 import java.security.CodeSource;
39 import java.security.PrivilegedAction;
40 import java.security.ProtectionDomain;
41 import java.security.cert.Certificate;
42 import java.util.ArrayDeque;
43 import java.util.Arrays;
44 import java.util.Collections;
45 import java.util.Deque;
46 import java.util.Enumeration;
47 import java.util.HashMap;
48 import java.util.HashSet;
49 import java.util.Hashtable;
50 import java.util.Map;
51 import java.util.NoSuchElementException;
52 import java.util.Objects;
53 import java.util.Set;
54 import java.util.Spliterator;
55 import java.util.Spliterators;
56 import java.util.Vector;
57 import java.util.WeakHashMap;
58 import java.util.concurrent.ConcurrentHashMap;
59 import java.util.function.Supplier;
60 import java.util.stream.Stream;
61 import java.util.stream.StreamSupport;
62
63 import jdk.internal.loader.BuiltinClassLoader;
64 import jdk.internal.perf.PerfCounter;
65 import jdk.internal.loader.BootLoader;
66 import jdk.internal.loader.ClassLoaders;
67 import jdk.internal.misc.Unsafe;
68 import jdk.internal.misc.VM;
69 import jdk.internal.ref.CleanerFactory;
70 import jdk.internal.reflect.CallerSensitive;
71 import jdk.internal.reflect.Reflection;
72 import sun.reflect.misc.ReflectUtil;
73 import sun.security.util.SecurityConstants;
74
75 /**
76 * A class loader is an object that is responsible for loading classes. The
77 * class {@code ClassLoader} is an abstract class. Given the <a
78 * href="#binary-name">binary name</a> of a class, a class loader should attempt to
79 * locate or generate data that constitutes a definition for the class. A
80 * typical strategy is to transform the name into a file name and then read a
81 * "class file" of that name from a file system.
82 *
83 * <p> Every {@link java.lang.Class Class} object contains a {@link
84 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
85 * it.
86 *
87 * <p> {@code Class} objects for array classes are not created by class
88 * loaders, but are created automatically as required by the Java runtime.
89 * The class loader for an array class, as returned by {@link
90 * Class#getClassLoader()} is the same as the class loader for its element
91 * type; if the element type is a primitive type, then the array class has no
92 * class loader.
93 *
94 * <p> Applications implement subclasses of {@code ClassLoader} in order to
95 * extend the manner in which the Java virtual machine dynamically loads
96 * classes.
97 *
98 * <p> Class loaders may typically be used by security managers to indicate
99 * security domains.
100 *
101 * <p> In addition to loading classes, a class loader is also responsible for
102 * locating resources. A resource is some data (a "{@code .class}" file,
103 * configuration data, or an image for example) that is identified with an
104 * abstract '/'-separated path name. Resources are typically packaged with an
105 * application or library so that they can be located by code in the
106 * application or library. In some cases, the resources are included so that
107 * they can be located by other libraries.
108 *
109 * <p> The {@code ClassLoader} class uses a delegation model to search for
110 * classes and resources. Each instance of {@code ClassLoader} has an
111 * associated parent class loader. When requested to find a class or
112 * resource, a {@code ClassLoader} instance will usually delegate the search
113 * for the class or resource to its parent class loader before attempting to
114 * find the class or resource itself.
115 *
116 * <p> Class loaders that support concurrent loading of classes are known as
117 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
118 * loaders and are required to register themselves at their class initialization
119 * time by invoking the {@link
120 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
121 * method. Note that the {@code ClassLoader} class is registered as parallel
122 * capable by default. However, its subclasses still need to register themselves
123 * if they are parallel capable.
124 * In environments in which the delegation model is not strictly
125 * hierarchical, class loaders need to be parallel capable, otherwise class
126 * loading can lead to deadlocks because the loader lock is held for the
127 * duration of the class loading process (see {@link #loadClass
128 * loadClass} methods).
129 *
130 * <h2> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h2>
131 *
132 * The Java run-time has the following built-in class loaders:
133 *
134 * <ul>
135 * <li><p>Bootstrap class loader.
136 * It is the virtual machine's built-in class loader, typically represented
137 * as {@code null}, and does not have a parent.</li>
138 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
139 * All <em>platform classes</em> are visible to the platform class loader
140 * that can be used as the parent of a {@code ClassLoader} instance.
141 * Platform classes include Java SE platform APIs, their implementation
142 * classes and JDK-specific run-time classes that are defined by the
143 * platform class loader or its ancestors.
144 * <p> To allow for upgrading/overriding of modules defined to the platform
145 * class loader, and where upgraded modules read modules defined to class
146 * loaders other than the platform class loader and its ancestors, then
147 * the platform class loader may have to delegate to other class loaders,
148 * the application class loader for example.
149 * In other words, classes in named modules defined to class loaders
150 * other than the platform class loader and its ancestors may be visible
151 * to the platform class loader. </li>
152 * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
153 * It is also known as <em>application class loader</em> and is distinct
154 * from the platform class loader.
155 * The system class loader is typically used to define classes on the
156 * application class path, module path, and JDK-specific tools.
157 * The platform class loader is a parent or an ancestor of the system class
158 * loader that all platform classes are visible to it.</li>
159 * </ul>
160 *
161 * <p> Normally, the Java virtual machine loads classes from the local file
162 * system in a platform-dependent manner.
163 * However, some classes may not originate from a file; they may originate
164 * from other sources, such as the network, or they could be constructed by an
165 * application. The method {@link #defineClass(String, byte[], int, int)
166 * defineClass} converts an array of bytes into an instance of class
167 * {@code Class}. Instances of this newly defined class can be created using
168 * {@link Class#newInstance Class.newInstance}.
169 *
170 * <p> The methods and constructors of objects created by a class loader may
171 * reference other classes. To determine the class(es) referred to, the Java
172 * virtual machine invokes the {@link #loadClass loadClass} method of
173 * the class loader that originally created the class.
174 *
175 * <p> For example, an application could create a network class loader to
176 * download class files from a server. Sample code might look like:
177 *
178 * <blockquote><pre>
179 * ClassLoader loader = new NetworkClassLoader(host, port);
180 * Object main = loader.loadClass("Main", true).newInstance();
181 * . . .
182 * </pre></blockquote>
183 *
184 * <p> The network class loader subclass must define the methods {@link
185 * #findClass findClass} and {@code loadClassData} to load a class
186 * from the network. Once it has downloaded the bytes that make up the class,
187 * it should use the method {@link #defineClass defineClass} to
188 * create a class instance. A sample implementation is:
189 *
190 * <blockquote><pre>
191 * class NetworkClassLoader extends ClassLoader {
192 * String host;
193 * int port;
194 *
195 * public Class findClass(String name) {
196 * byte[] b = loadClassData(name);
197 * return defineClass(name, b, 0, b.length);
198 * }
199 *
200 * private byte[] loadClassData(String name) {
201 * // load the class data from the connection
202 * . . .
203 * }
204 * }
205 * </pre></blockquote>
206 *
207 * <h3> <a id="binary-name">Binary names</a> </h3>
208 *
209 * <p> Any class name provided as a {@code String} parameter to methods in
210 * {@code ClassLoader} must be a binary name as defined by
211 * <cite>The Java™ Language Specification</cite>.
212 *
213 * <p> Examples of valid class names include:
214 * <blockquote><pre>
215 * "java.lang.String"
216 * "javax.swing.JSpinner$DefaultEditor"
217 * "java.security.KeyStore$Builder$FileBuilder$1"
218 * "java.net.URLClassLoader$3$1"
219 * </pre></blockquote>
220 *
221 * <p> Any package name provided as a {@code String} parameter to methods in
222 * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
223 * or a fully qualified name as defined by
224 * <cite>The Java™ Language Specification</cite>.
225 *
226 * @jls 6.7 Fully Qualified Names
227 * @jls 13.1 The Form of a Binary
228 * @see #resolveClass(Class)
229 * @since 1.0
230 * @revised 9
231 * @spec JPMS
232 */
233 public abstract class ClassLoader {
234
235 private static native void registerNatives();
236 static {
237 registerNatives();
238 }
239
240 // The parent class loader for delegation
241 // Note: VM hardcoded the offset of this field, thus all new fields
242 // must be added *after* it.
243 private final ClassLoader parent;
244
245 // class loader name
246 private final String name;
247
248 // the unnamed module for this ClassLoader
249 private final Module unnamedModule;
250
251 // a string for exception message printing
252 private final String nameAndId;
253
254 /**
255 * Encapsulates the set of parallel capable loader types.
256 */
257 private static class ParallelLoaders {
258 private ParallelLoaders() {}
259
260 // the set of parallel capable loader types
261 private static final Set<Class<? extends ClassLoader>> loaderTypes =
262 Collections.newSetFromMap(new WeakHashMap<>());
263 static {
264 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
265 }
266
267 /**
268 * Registers the given class loader type as parallel capable.
269 * Returns {@code true} is successfully registered; {@code false} if
270 * loader's super class is not registered.
271 */
272 static boolean register(Class<? extends ClassLoader> c) {
273 synchronized (loaderTypes) {
274 if (loaderTypes.contains(c.getSuperclass())) {
275 // register the class loader as parallel capable
276 // if and only if all of its super classes are.
277 // Note: given current classloading sequence, if
278 // the immediate super class is parallel capable,
279 // all the super classes higher up must be too.
280 loaderTypes.add(c);
281 return true;
282 } else {
283 return false;
284 }
285 }
286 }
287
288 /**
289 * Returns {@code true} if the given class loader type is
290 * registered as parallel capable.
291 */
292 static boolean isRegistered(Class<? extends ClassLoader> c) {
293 synchronized (loaderTypes) {
294 return loaderTypes.contains(c);
295 }
296 }
297 }
298
299 // Maps class name to the corresponding lock object when the current
300 // class loader is parallel capable.
301 // Note: VM also uses this field to decide if the current class loader
302 // is parallel capable and the appropriate lock object for class loading.
303 private final ConcurrentHashMap<String, Object> parallelLockMap;
304
305 // Maps packages to certs
306 private final Map <String, Certificate[]> package2certs;
307
308 // Shared among all packages with unsigned classes
309 private static final Certificate[] nocerts = new Certificate[0];
310
311 // The classes loaded by this class loader. The only purpose of this table
312 // is to keep the classes from being GC'ed until the loader is GC'ed.
313 private final Vector<Class<?>> classes = new Vector<>();
314
315 // The "default" domain. Set as the default ProtectionDomain on newly
316 // created classes.
317 private final ProtectionDomain defaultDomain =
318 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
319 null, this, null);
320
321 // Invoked by the VM to record every loaded class with this loader.
322 void addClass(Class<?> c) {
323 classes.addElement(c);
324 }
325
326 // The packages defined in this class loader. Each package name is
327 // mapped to its corresponding NamedPackage object.
328 //
329 // The value is a Package object if ClassLoader::definePackage,
330 // Class::getPackage, ClassLoader::getDefinePackage(s) or
331 // Package::getPackage(s) method is called to define it.
332 // Otherwise, the value is a NamedPackage object.
333 private final ConcurrentHashMap<String, NamedPackage> packages
334 = new ConcurrentHashMap<>();
335
336 /*
337 * Returns a named package for the given module.
338 */
339 private NamedPackage getNamedPackage(String pn, Module m) {
340 NamedPackage p = packages.get(pn);
341 if (p == null) {
342 p = new NamedPackage(pn, m);
343
344 NamedPackage value = packages.putIfAbsent(pn, p);
345 if (value != null) {
346 // Package object already be defined for the named package
347 p = value;
348 // if definePackage is called by this class loader to define
349 // a package in a named module, this will return Package
350 // object of the same name. Package object may contain
351 // unexpected information but it does not impact the runtime.
352 // this assertion may be helpful for troubleshooting
353 assert value.module() == m;
354 }
355 }
356 return p;
357 }
358
359 private static Void checkCreateClassLoader() {
360 return checkCreateClassLoader(null);
361 }
362
363 private static Void checkCreateClassLoader(String name) {
364 if (name != null && name.isEmpty()) {
365 throw new IllegalArgumentException("name must be non-empty or null");
366 }
367
368 SecurityManager security = System.getSecurityManager();
369 if (security != null) {
370 security.checkCreateClassLoader();
371 }
372 return null;
373 }
374
375 private ClassLoader(Void unused, String name, ClassLoader parent) {
376 this.name = name;
377 this.parent = parent;
378 this.unnamedModule = new Module(this);
379 if (ParallelLoaders.isRegistered(this.getClass())) {
380 parallelLockMap = new ConcurrentHashMap<>();
381 package2certs = new ConcurrentHashMap<>();
382 assertionLock = new Object();
383 } else {
384 // no finer-grained lock; lock on the classloader instance
385 parallelLockMap = null;
386 package2certs = new Hashtable<>();
387 assertionLock = this;
388 }
389 this.nameAndId = nameAndId(this);
390 }
391
392 /**
393 * If the defining loader has a name explicitly set then
394 * '<loader-name>' @<id>
395 * If the defining loader has no name then
396 * <qualified-class-name> @<id>
397 * If it's built-in loader then omit `@<id>` as there is only one instance.
398 */
399 private static String nameAndId(ClassLoader ld) {
400 String nid = ld.getName() != null ? "\'" + ld.getName() + "\'"
401 : ld.getClass().getName();
402 if (!(ld instanceof BuiltinClassLoader)) {
403 String id = Integer.toHexString(System.identityHashCode(ld));
404 nid = nid + " @" + id;
405 }
406 return nid;
407 }
408
409 /**
410 * Creates a new class loader of the specified name and using the
411 * specified parent class loader for delegation.
412 *
413 * @apiNote If the parent is specified as {@code null} (for the
414 * bootstrap class loader) then there is no guarantee that all platform
415 * classes are visible.
416 *
417 * @param name class loader name; or {@code null} if not named
418 * @param parent the parent class loader
419 *
420 * @throws IllegalArgumentException if the given name is empty.
421 *
422 * @throws SecurityException
423 * If a security manager exists and its
424 * {@link SecurityManager#checkCreateClassLoader()}
425 * method doesn't allow creation of a new class loader.
426 *
427 * @since 9
428 * @spec JPMS
429 */
430 protected ClassLoader(String name, ClassLoader parent) {
431 this(checkCreateClassLoader(name), name, parent);
432 }
433
434 /**
435 * Creates a new class loader using the specified parent class loader for
436 * delegation.
437 *
438 * <p> If there is a security manager, its {@link
439 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
440 * is invoked. This may result in a security exception. </p>
441 *
442 * @apiNote If the parent is specified as {@code null} (for the
443 * bootstrap class loader) then there is no guarantee that all platform
444 * classes are visible.
445 *
446 * @param parent
447 * The parent class loader
448 *
449 * @throws SecurityException
450 * If a security manager exists and its
451 * {@code checkCreateClassLoader} method doesn't allow creation
452 * of a new class loader.
453 *
454 * @since 1.2
455 */
456 protected ClassLoader(ClassLoader parent) {
457 this(checkCreateClassLoader(), null, parent);
458 }
459
460 /**
461 * Creates a new class loader using the {@code ClassLoader} returned by
462 * the method {@link #getSystemClassLoader()
463 * getSystemClassLoader()} as the parent class loader.
464 *
465 * <p> If there is a security manager, its {@link
466 * SecurityManager#checkCreateClassLoader()
467 * checkCreateClassLoader} method is invoked. This may result in
468 * a security exception. </p>
469 *
470 * @throws SecurityException
471 * If a security manager exists and its
472 * {@code checkCreateClassLoader} method doesn't allow creation
473 * of a new class loader.
474 */
475 protected ClassLoader() {
476 this(checkCreateClassLoader(), null, getSystemClassLoader());
477 }
478
479 /**
480 * Returns the name of this class loader or {@code null} if
481 * this class loader is not named.
482 *
483 * @apiNote This method is non-final for compatibility. If this
484 * method is overridden, this method must return the same name
485 * as specified when this class loader was instantiated.
486 *
487 * @return name of this class loader; or {@code null} if
488 * this class loader is not named.
489 *
490 * @since 9
491 * @spec JPMS
492 */
493 public String getName() {
494 return name;
495 }
496
497 // package-private used by StackTraceElement to avoid
498 // calling the overrideable getName method
499 final String name() {
500 return name;
501 }
502
503 // -- Class --
504
505 /**
506 * Loads the class with the specified <a href="#binary-name">binary name</a>.
507 * This method searches for classes in the same manner as the {@link
508 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
509 * machine to resolve class references. Invoking this method is equivalent
510 * to invoking {@link #loadClass(String, boolean) loadClass(name,
511 * false)}.
512 *
513 * @param name
514 * The <a href="#binary-name">binary name</a> of the class
515 *
516 * @return The resulting {@code Class} object
517 *
518 * @throws ClassNotFoundException
519 * If the class was not found
520 */
521 public Class<?> loadClass(String name) throws ClassNotFoundException {
522 return loadClass(name, false);
523 }
524
525 /**
526 * Loads the class with the specified <a href="#binary-name">binary name</a>. The
527 * default implementation of this method searches for classes in the
528 * following order:
529 *
530 * <ol>
531 *
532 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
533 * has already been loaded. </p></li>
534 *
535 * <li><p> Invoke the {@link #loadClass(String) loadClass} method
536 * on the parent class loader. If the parent is {@code null} the class
537 * loader built into the virtual machine is used, instead. </p></li>
538 *
539 * <li><p> Invoke the {@link #findClass(String)} method to find the
540 * class. </p></li>
541 *
542 * </ol>
543 *
544 * <p> If the class was found using the above steps, and the
545 * {@code resolve} flag is true, this method will then invoke the {@link
546 * #resolveClass(Class)} method on the resulting {@code Class} object.
547 *
548 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
549 * #findClass(String)}, rather than this method. </p>
550 *
551 * <p> Unless overridden, this method synchronizes on the result of
552 * {@link #getClassLoadingLock getClassLoadingLock} method
553 * during the entire class loading process.
554 *
555 * @param name
556 * The <a href="#binary-name">binary name</a> of the class
557 *
558 * @param resolve
559 * If {@code true} then resolve the class
560 *
561 * @return The resulting {@code Class} object
562 *
563 * @throws ClassNotFoundException
564 * If the class could not be found
565 */
566 protected Class<?> loadClass(String name, boolean resolve)
567 throws ClassNotFoundException
568 {
569 synchronized (getClassLoadingLock(name)) {
570 // First, check if the class has already been loaded
571 Class<?> c = findLoadedClass(name);
572 if (c == null) {
573 long t0 = System.nanoTime();
574 try {
575 if (parent != null) {
576 c = parent.loadClass(name, false);
577 } else {
578 c = findBootstrapClassOrNull(name);
579 }
580 } catch (ClassNotFoundException e) {
581 // ClassNotFoundException thrown if class not found
582 // from the non-null parent class loader
583 }
584
585 if (c == null) {
586 // If still not found, then invoke findClass in order
587 // to find the class.
588 long t1 = System.nanoTime();
589 c = findClass(name);
590
591 // this is the defining class loader; record the stats
592 PerfCounter.getParentDelegationTime().addTime(t1 - t0);
593 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
594 PerfCounter.getFindClasses().increment();
595 }
596 }
597 if (resolve) {
598 resolveClass(c);
599 }
600 return c;
601 }
602 }
603
604 /**
605 * Loads the class with the specified <a href="#binary-name">binary name</a>
606 * in a module defined to this class loader. This method returns {@code null}
607 * if the class could not be found.
608 *
609 * @apiNote This method does not delegate to the parent class loader.
610 *
611 * @implSpec The default implementation of this method searches for classes
612 * in the following order:
613 *
614 * <ol>
615 * <li>Invoke {@link #findLoadedClass(String)} to check if the class
616 * has already been loaded.</li>
617 * <li>Invoke the {@link #findClass(String, String)} method to find the
618 * class in the given module.</li>
619 * </ol>
620 *
621 * @param module
622 * The module
623 * @param name
624 * The <a href="#binary-name">binary name</a> of the class
625 *
626 * @return The resulting {@code Class} object in a module defined by
627 * this class loader, or {@code null} if the class could not be found.
628 */
629 final Class<?> loadClass(Module module, String name) {
630 synchronized (getClassLoadingLock(name)) {
631 // First, check if the class has already been loaded
632 Class<?> c = findLoadedClass(name);
633 if (c == null) {
634 c = findClass(module.getName(), name);
635 }
636 if (c != null && c.getModule() == module) {
637 return c;
638 } else {
639 return null;
640 }
641 }
642 }
643
644 /**
645 * Returns the lock object for class loading operations.
646 * For backward compatibility, the default implementation of this method
647 * behaves as follows. If this ClassLoader object is registered as
648 * parallel capable, the method returns a dedicated object associated
649 * with the specified class name. Otherwise, the method returns this
650 * ClassLoader object.
651 *
652 * @param className
653 * The name of the to-be-loaded class
654 *
655 * @return the lock for class loading operations
656 *
657 * @throws NullPointerException
658 * If registered as parallel capable and {@code className} is null
659 *
660 * @see #loadClass(String, boolean)
661 *
662 * @since 1.7
663 */
664 protected Object getClassLoadingLock(String className) {
665 Object lock = this;
666 if (parallelLockMap != null) {
667 Object newLock = new Object();
668 lock = parallelLockMap.putIfAbsent(className, newLock);
669 if (lock == null) {
670 lock = newLock;
671 }
672 }
673 return lock;
674 }
675
676 // Invoked by the VM after loading class with this loader.
677 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
678 final SecurityManager sm = System.getSecurityManager();
679 if (sm != null) {
680 if (ReflectUtil.isNonPublicProxyClass(cls)) {
681 for (Class<?> intf: cls.getInterfaces()) {
682 checkPackageAccess(intf, pd);
683 }
684 return;
685 }
686
687 final String packageName = cls.getPackageName();
688 if (!packageName.isEmpty()) {
689 AccessController.doPrivileged(new PrivilegedAction<>() {
690 public Void run() {
691 sm.checkPackageAccess(packageName);
692 return null;
693 }
694 }, new AccessControlContext(new ProtectionDomain[] {pd}));
695 }
696 }
697 }
698
699 /**
700 * Finds the class with the specified <a href="#binary-name">binary name</a>.
701 * This method should be overridden by class loader implementations that
702 * follow the delegation model for loading classes, and will be invoked by
703 * the {@link #loadClass loadClass} method after checking the
704 * parent class loader for the requested class.
705 *
706 * @implSpec The default implementation throws {@code ClassNotFoundException}.
707 *
708 * @param name
709 * The <a href="#binary-name">binary name</a> of the class
710 *
711 * @return The resulting {@code Class} object
712 *
713 * @throws ClassNotFoundException
714 * If the class could not be found
715 *
716 * @since 1.2
717 */
718 protected Class<?> findClass(String name) throws ClassNotFoundException {
719 throw new ClassNotFoundException(name);
720 }
721
722 /**
723 * Finds the class with the given <a href="#binary-name">binary name</a>
724 * in a module defined to this class loader.
725 * Class loader implementations that support loading from modules
726 * should override this method.
727 *
728 * @apiNote This method returns {@code null} rather than throwing
729 * {@code ClassNotFoundException} if the class could not be found.
730 *
731 * @implSpec The default implementation attempts to find the class by
732 * invoking {@link #findClass(String)} when the {@code moduleName} is
733 * {@code null}. It otherwise returns {@code null}.
734 *
735 * @param moduleName
736 * The module name; or {@code null} to find the class in the
737 * {@linkplain #getUnnamedModule() unnamed module} for this
738 * class loader
739
740 * @param name
741 * The <a href="#binary-name">binary name</a> of the class
742 *
743 * @return The resulting {@code Class} object, or {@code null}
744 * if the class could not be found.
745 *
746 * @since 9
747 * @spec JPMS
748 */
749 protected Class<?> findClass(String moduleName, String name) {
750 if (moduleName == null) {
751 try {
752 return findClass(name);
753 } catch (ClassNotFoundException ignore) { }
754 }
755 return null;
756 }
757
758
759 /**
760 * Converts an array of bytes into an instance of class {@code Class}.
761 * Before the {@code Class} can be used it must be resolved. This method
762 * is deprecated in favor of the version that takes a <a
763 * href="#binary-name">binary name</a> as its first argument, and is more secure.
764 *
765 * @param b
766 * The bytes that make up the class data. The bytes in positions
767 * {@code off} through {@code off+len-1} should have the format
768 * of a valid class file as defined by
769 * <cite>The Java™ Virtual Machine Specification</cite>.
770 *
771 * @param off
772 * The start offset in {@code b} of the class data
773 *
774 * @param len
775 * The length of the class data
776 *
777 * @return The {@code Class} object that was created from the specified
778 * class data
779 *
780 * @throws ClassFormatError
781 * If the data did not contain a valid class
782 *
783 * @throws IndexOutOfBoundsException
784 * If either {@code off} or {@code len} is negative, or if
785 * {@code off+len} is greater than {@code b.length}.
786 *
787 * @throws SecurityException
788 * If an attempt is made to add this class to a package that
789 * contains classes that were signed by a different set of
790 * certificates than this class, or if an attempt is made
791 * to define a class in a package with a fully-qualified name
792 * that starts with "{@code java.}".
793 *
794 * @see #loadClass(String, boolean)
795 * @see #resolveClass(Class)
796 *
797 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
798 * defineClass(String, byte[], int, int)}
799 */
800 @Deprecated(since="1.1")
801 protected final Class<?> defineClass(byte[] b, int off, int len)
802 throws ClassFormatError
803 {
804 return defineClass(null, b, off, len, null);
805 }
806
807 /**
808 * Converts an array of bytes into an instance of class {@code Class}.
809 * Before the {@code Class} can be used it must be resolved.
810 *
811 * <p> This method assigns a default {@link java.security.ProtectionDomain
812 * ProtectionDomain} to the newly defined class. The
813 * {@code ProtectionDomain} is effectively granted the same set of
814 * permissions returned when {@link
815 * java.security.Policy#getPermissions(java.security.CodeSource)
816 * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
817 * is invoked. The default protection domain is created on the first invocation
818 * of {@link #defineClass(String, byte[], int, int) defineClass},
819 * and re-used on subsequent invocations.
820 *
821 * <p> To assign a specific {@code ProtectionDomain} to the class, use
822 * the {@link #defineClass(String, byte[], int, int,
823 * java.security.ProtectionDomain) defineClass} method that takes a
824 * {@code ProtectionDomain} as one of its arguments. </p>
825 *
826 * <p>
827 * This method defines a package in this class loader corresponding to the
828 * package of the {@code Class} (if such a package has not already been defined
829 * in this class loader). The name of the defined package is derived from
830 * the <a href="#binary-name">binary name</a> of the class specified by
831 * the byte array {@code b}.
832 * Other properties of the defined package are as specified by {@link Package}.
833 *
834 * @param name
835 * The expected <a href="#binary-name">binary name</a> of the class, or
836 * {@code null} if not known
837 *
838 * @param b
839 * The bytes that make up the class data. The bytes in positions
840 * {@code off} through {@code off+len-1} should have the format
841 * of a valid class file as defined by
842 * <cite>The Java™ Virtual Machine Specification</cite>.
843 *
844 * @param off
845 * The start offset in {@code b} of the class data
846 *
847 * @param len
848 * The length of the class data
849 *
850 * @return The {@code Class} object that was created from the specified
851 * class data.
852 *
853 * @throws ClassFormatError
854 * If the data did not contain a valid class
855 *
856 * @throws IndexOutOfBoundsException
857 * If either {@code off} or {@code len} is negative, or if
858 * {@code off+len} is greater than {@code b.length}.
859 *
860 * @throws SecurityException
861 * If an attempt is made to add this class to a package that
862 * contains classes that were signed by a different set of
863 * certificates than this class (which is unsigned), or if
864 * {@code name} begins with "{@code java.}".
865 *
866 * @see #loadClass(String, boolean)
867 * @see #resolveClass(Class)
868 * @see java.security.CodeSource
869 * @see java.security.SecureClassLoader
870 *
871 * @since 1.1
872 * @revised 9
873 * @spec JPMS
874 */
875 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
876 throws ClassFormatError
877 {
878 return defineClass(name, b, off, len, null);
879 }
880
881 /* Determine protection domain, and check that:
882 - not define java.* class,
883 - signer of this class matches signers for the rest of the classes in
884 package.
885 */
886 private ProtectionDomain preDefineClass(String name,
887 ProtectionDomain pd)
888 {
889 if (!checkName(name))
890 throw new NoClassDefFoundError("IllegalName: " + name);
891
892 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
893 // relies on the fact that spoofing is impossible if a class has a name
894 // of the form "java.*"
895 if ((name != null) && name.startsWith("java.")
896 && this != getBuiltinPlatformClassLoader()) {
897 throw new SecurityException
898 ("Prohibited package name: " +
899 name.substring(0, name.lastIndexOf('.')));
900 }
901 if (pd == null) {
902 pd = defaultDomain;
903 }
904
905 if (name != null) {
906 checkCerts(name, pd.getCodeSource());
907 }
908
909 return pd;
910 }
911
912 private String defineClassSourceLocation(ProtectionDomain pd) {
913 CodeSource cs = pd.getCodeSource();
914 String source = null;
915 if (cs != null && cs.getLocation() != null) {
916 source = cs.getLocation().toString();
917 }
918 return source;
919 }
920
921 private void postDefineClass(Class<?> c, ProtectionDomain pd) {
922 // define a named package, if not present
923 getNamedPackage(c.getPackageName(), c.getModule());
924
925 if (pd.getCodeSource() != null) {
926 Certificate certs[] = pd.getCodeSource().getCertificates();
927 if (certs != null)
928 setSigners(c, certs);
929 }
930 }
931
932 /**
933 * Converts an array of bytes into an instance of class {@code Class},
934 * with a given {@code ProtectionDomain}.
935 *
936 * <p> If the given {@code ProtectionDomain} is {@code null},
937 * then a default protection domain will be assigned to the class as specified
938 * in the documentation for {@link #defineClass(String, byte[], int, int)}.
939 * Before the class can be used it must be resolved.
940 *
941 * <p> The first class defined in a package determines the exact set of
942 * certificates that all subsequent classes defined in that package must
943 * contain. The set of certificates for a class is obtained from the
944 * {@link java.security.CodeSource CodeSource} within the
945 * {@code ProtectionDomain} of the class. Any classes added to that
946 * package must contain the same set of certificates or a
947 * {@code SecurityException} will be thrown. Note that if
948 * {@code name} is {@code null}, this check is not performed.
949 * You should always pass in the <a href="#binary-name">binary name</a> of the
950 * class you are defining as well as the bytes. This ensures that the
951 * class you are defining is indeed the class you think it is.
952 *
953 * <p> If the specified {@code name} begins with "{@code java.}", it can
954 * only be defined by the {@linkplain #getPlatformClassLoader()
955 * platform class loader} or its ancestors; otherwise {@code SecurityException}
956 * will be thrown. If {@code name} is not {@code null}, it must be equal to
957 * the <a href="#binary-name">binary name</a> of the class
958 * specified by the byte array {@code b}, otherwise a {@link
959 * NoClassDefFoundError NoClassDefFoundError} will be thrown.
960 *
961 * <p> This method defines a package in this class loader corresponding to the
962 * package of the {@code Class} (if such a package has not already been defined
963 * in this class loader). The name of the defined package is derived from
964 * the <a href="#binary-name">binary name</a> of the class specified by
965 * the byte array {@code b}.
966 * Other properties of the defined package are as specified by {@link Package}.
967 *
968 * @param name
969 * The expected <a href="#binary-name">binary name</a> of the class, or
970 * {@code null} if not known
971 *
972 * @param b
973 * The bytes that make up the class data. The bytes in positions
974 * {@code off} through {@code off+len-1} should have the format
975 * of a valid class file as defined by
976 * <cite>The Java™ Virtual Machine Specification</cite>.
977 *
978 * @param off
979 * The start offset in {@code b} of the class data
980 *
981 * @param len
982 * The length of the class data
983 *
984 * @param protectionDomain
985 * The {@code ProtectionDomain} of the class
986 *
987 * @return The {@code Class} object created from the data,
988 * and {@code ProtectionDomain}.
989 *
990 * @throws ClassFormatError
991 * If the data did not contain a valid class
992 *
993 * @throws NoClassDefFoundError
994 * If {@code name} is not {@code null} and not equal to the
995 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
996 *
997 * @throws IndexOutOfBoundsException
998 * If either {@code off} or {@code len} is negative, or if
999 * {@code off+len} is greater than {@code b.length}.
1000 *
1001 * @throws SecurityException
1002 * If an attempt is made to add this class to a package that
1003 * contains classes that were signed by a different set of
1004 * certificates than this class, or if {@code name} begins with
1005 * "{@code java.}" and this class loader is not the platform
1006 * class loader or its ancestor.
1007 *
1008 * @revised 9
1009 * @spec JPMS
1010 */
1011 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
1012 ProtectionDomain protectionDomain)
1013 throws ClassFormatError
1014 {
1015 protectionDomain = preDefineClass(name, protectionDomain);
1016 String source = defineClassSourceLocation(protectionDomain);
1017 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
1018 postDefineClass(c, protectionDomain);
1019 return c;
1020 }
1021
1022 /**
1023 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
1024 * of class {@code Class}, with the given {@code ProtectionDomain}.
1025 * If the given {@code ProtectionDomain} is {@code null}, then a default
1026 * protection domain will be assigned to the class as
1027 * specified in the documentation for {@link #defineClass(String, byte[],
1028 * int, int)}. Before the class can be used it must be resolved.
1029 *
1030 * <p>The rules about the first class defined in a package determining the
1031 * set of certificates for the package, the restrictions on class names,
1032 * and the defined package of the class
1033 * are identical to those specified in the documentation for {@link
1034 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
1035 *
1036 * <p> An invocation of this method of the form
1037 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
1038 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
1039 * result as the statements
1040 *
1041 *<p> <code>
1042 * ...<br>
1043 * byte[] temp = new byte[bBuffer.{@link
1044 * java.nio.ByteBuffer#remaining remaining}()];<br>
1045 * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
1046 * get}(temp);<br>
1047 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
1048 * cl.defineClass}(name, temp, 0,
1049 * temp.length, pd);<br>
1050 * </code></p>
1051 *
1052 * @param name
1053 * The expected <a href="#binary-name">binary name</a>. of the class, or
1054 * {@code null} if not known
1055 *
1056 * @param b
1057 * The bytes that make up the class data. The bytes from positions
1058 * {@code b.position()} through {@code b.position() + b.limit() -1
1059 * } should have the format of a valid class file as defined by
1060 * <cite>The Java™ Virtual Machine Specification</cite>.
1061 *
1062 * @param protectionDomain
1063 * The {@code ProtectionDomain} of the class, or {@code null}.
1064 *
1065 * @return The {@code Class} object created from the data,
1066 * and {@code ProtectionDomain}.
1067 *
1068 * @throws ClassFormatError
1069 * If the data did not contain a valid class.
1070 *
1071 * @throws NoClassDefFoundError
1072 * If {@code name} is not {@code null} and not equal to the
1073 * <a href="#binary-name">binary name</a> of the class specified by {@code b}
1074 *
1075 * @throws SecurityException
1076 * If an attempt is made to add this class to a package that
1077 * contains classes that were signed by a different set of
1078 * certificates than this class, or if {@code name} begins with
1079 * "{@code java.}".
1080 *
1081 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
1082 *
1083 * @since 1.5
1084 * @revised 9
1085 * @spec JPMS
1086 */
1087 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
1088 ProtectionDomain protectionDomain)
1089 throws ClassFormatError
1090 {
1091 int len = b.remaining();
1092
1093 // Use byte[] if not a direct ByteBuffer:
1094 if (!b.isDirect()) {
1095 if (b.hasArray()) {
1096 return defineClass(name, b.array(),
1097 b.position() + b.arrayOffset(), len,
1098 protectionDomain);
1099 } else {
1100 // no array, or read-only array
1101 byte[] tb = new byte[len];
1102 b.get(tb); // get bytes out of byte buffer.
1103 return defineClass(name, tb, 0, len, protectionDomain);
1104 }
1105 }
1106
1107 protectionDomain = preDefineClass(name, protectionDomain);
1108 String source = defineClassSourceLocation(protectionDomain);
1109 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
1110 postDefineClass(c, protectionDomain);
1111 return c;
1112 }
1113
1114 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
1115 ProtectionDomain pd, String source);
1116
1117 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
1118 int off, int len, ProtectionDomain pd,
1119 String source);
1120
1121 /**
1122 * Defines a class of the given flags via Lookup.defineClass.
1123 *
1124 * @param loader the defining loader
1125 * @param lookup nest host of the Class to be defined
1126 * @param name the binary name or {@code null} if not findable
1127 * @param b class bytes
1128 * @param off the start offset in {@code b} of the class bytes
1129 * @param len the length of the class bytes
1130 * @param pd protection domain
1131 * @param initialize initialize the class
1132 * @param flags flags
1133 * @param classData class data
1134 */
1135 static native Class<?> defineClass0(ClassLoader loader,
1136 Class<?> lookup,
1137 String name,
1138 byte[] b, int off, int len,
1139 ProtectionDomain pd,
1140 boolean initialize,
1141 int flags,
1142 Object classData);
1143
1144 // true if the name is null or has the potential to be a valid binary name
1145 private boolean checkName(String name) {
1146 if ((name == null) || (name.isEmpty()))
1147 return true;
1148 if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
1149 return false;
1150 return true;
1151 }
1152
1153 private void checkCerts(String name, CodeSource cs) {
1154 int i = name.lastIndexOf('.');
1155 String pname = (i == -1) ? "" : name.substring(0, i);
1156
1157 Certificate[] certs = null;
1158 if (cs != null) {
1159 certs = cs.getCertificates();
1160 }
1161 Certificate[] pcerts = null;
1162 if (parallelLockMap == null) {
1163 synchronized (this) {
1164 pcerts = package2certs.get(pname);
1165 if (pcerts == null) {
1166 package2certs.put(pname, (certs == null? nocerts:certs));
1167 }
1168 }
1169 } else {
1170 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
1171 putIfAbsent(pname, (certs == null? nocerts:certs));
1172 }
1173 if (pcerts != null && !compareCerts(pcerts, certs)) {
1174 throw new SecurityException("class \"" + name
1175 + "\"'s signer information does not match signer information"
1176 + " of other classes in the same package");
1177 }
1178 }
1179
1180 /**
1181 * check to make sure the certs for the new class (certs) are the same as
1182 * the certs for the first class inserted in the package (pcerts)
1183 */
1184 private boolean compareCerts(Certificate[] pcerts,
1185 Certificate[] certs)
1186 {
1187 // certs can be null, indicating no certs.
1188 if ((certs == null) || (certs.length == 0)) {
1189 return pcerts.length == 0;
1190 }
1191
1192 // the length must be the same at this point
1193 if (certs.length != pcerts.length)
1194 return false;
1195
1196 // go through and make sure all the certs in one array
1197 // are in the other and vice-versa.
1198 boolean match;
1199 for (Certificate cert : certs) {
1200 match = false;
1201 for (Certificate pcert : pcerts) {
1202 if (cert.equals(pcert)) {
1203 match = true;
1204 break;
1205 }
1206 }
1207 if (!match) return false;
1208 }
1209
1210 // now do the same for pcerts
1211 for (Certificate pcert : pcerts) {
1212 match = false;
1213 for (Certificate cert : certs) {
1214 if (pcert.equals(cert)) {
1215 match = true;
1216 break;
1217 }
1218 }
1219 if (!match) return false;
1220 }
1221
1222 return true;
1223 }
1224
1225 /**
1226 * Links the specified class. This (misleadingly named) method may be
1227 * used by a class loader to link a class. If the class {@code c} has
1228 * already been linked, then this method simply returns. Otherwise, the
1229 * class is linked as described in the "Execution" chapter of
1230 * <cite>The Java™ Language Specification</cite>.
1231 *
1232 * @param c
1233 * The class to link
1234 *
1235 * @throws NullPointerException
1236 * If {@code c} is {@code null}.
1237 *
1238 * @see #defineClass(String, byte[], int, int)
1239 */
1240 protected final void resolveClass(Class<?> c) {
1241 if (c == null) {
1242 throw new NullPointerException();
1243 }
1244 }
1245
1246 /**
1247 * Finds a class with the specified <a href="#binary-name">binary name</a>,
1248 * loading it if necessary.
1249 *
1250 * <p> This method loads the class through the system class loader (see
1251 * {@link #getSystemClassLoader()}). The {@code Class} object returned
1252 * might have more than one {@code ClassLoader} associated with it.
1253 * Subclasses of {@code ClassLoader} need not usually invoke this method,
1254 * because most class loaders need to override just {@link
1255 * #findClass(String)}. </p>
1256 *
1257 * @param name
1258 * The <a href="#binary-name">binary name</a> of the class
1259 *
1260 * @return The {@code Class} object for the specified {@code name}
1261 *
1262 * @throws ClassNotFoundException
1263 * If the class could not be found
1264 *
1265 * @see #ClassLoader(ClassLoader)
1266 * @see #getParent()
1267 */
1268 protected final Class<?> findSystemClass(String name)
1269 throws ClassNotFoundException
1270 {
1271 return getSystemClassLoader().loadClass(name);
1272 }
1273
1274 /**
1275 * Returns a class loaded by the bootstrap class loader;
1276 * or return null if not found.
1277 */
1278 Class<?> findBootstrapClassOrNull(String name) {
1279 if (!checkName(name)) return null;
1280
1281 return findBootstrapClass(name);
1282 }
1283
1284 // return null if not found
1285 private native Class<?> findBootstrapClass(String name);
1286
1287 /**
1288 * Returns the class with the given <a href="#binary-name">binary name</a> if this
1289 * loader has been recorded by the Java virtual machine as an initiating
1290 * loader of a class with that <a href="#binary-name">binary name</a>. Otherwise
1291 * {@code null} is returned.
1292 *
1293 * @param name
1294 * The <a href="#binary-name">binary name</a> of the class
1295 *
1296 * @return The {@code Class} object, or {@code null} if the class has
1297 * not been loaded
1298 *
1299 * @since 1.1
1300 */
1301 protected final Class<?> findLoadedClass(String name) {
1302 if (!checkName(name))
1303 return null;
1304 return findLoadedClass0(name);
1305 }
1306
1307 private final native Class<?> findLoadedClass0(String name);
1308
1309 /**
1310 * Sets the signers of a class. This should be invoked after defining a
1311 * class.
1312 *
1313 * @param c
1314 * The {@code Class} object
1315 *
1316 * @param signers
1317 * The signers for the class
1318 *
1319 * @since 1.1
1320 */
1321 protected final void setSigners(Class<?> c, Object[] signers) {
1322 c.setSigners(signers);
1323 }
1324
1325
1326 // -- Resources --
1327
1328 /**
1329 * Returns a URL to a resource in a module defined to this class loader.
1330 * Class loader implementations that support loading from modules
1331 * should override this method.
1332 *
1333 * @apiNote This method is the basis for the {@link
1334 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
1335 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
1336 * Module.getResourceAsStream} methods. It is not subject to the rules for
1337 * encapsulation specified by {@code Module.getResourceAsStream}.
1338 *
1339 * @implSpec The default implementation attempts to find the resource by
1340 * invoking {@link #findResource(String)} when the {@code moduleName} is
1341 * {@code null}. It otherwise returns {@code null}.
1342 *
1343 * @param moduleName
1344 * The module name; or {@code null} to find a resource in the
1345 * {@linkplain #getUnnamedModule() unnamed module} for this
1346 * class loader
1347 * @param name
1348 * The resource name
1349 *
1350 * @return A URL to the resource; {@code null} if the resource could not be
1351 * found, a URL could not be constructed to locate the resource,
1352 * access to the resource is denied by the security manager, or
1353 * there isn't a module of the given name defined to the class
1354 * loader.
1355 *
1356 * @throws IOException
1357 * If I/O errors occur
1358 *
1359 * @see java.lang.module.ModuleReader#find(String)
1360 * @since 9
1361 * @spec JPMS
1362 */
1363 protected URL findResource(String moduleName, String name) throws IOException {
1364 if (moduleName == null) {
1365 return findResource(name);
1366 } else {
1367 return null;
1368 }
1369 }
1370
1371 /**
1372 * Finds the resource with the given name. A resource is some data
1373 * (images, audio, text, etc) that can be accessed by class code in a way
1374 * that is independent of the location of the code.
1375 *
1376 * <p> The name of a resource is a '{@code /}'-separated path name that
1377 * identifies the resource. </p>
1378 *
1379 * <p> Resources in named modules are subject to the encapsulation rules
1380 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1381 * Additionally, and except for the special case where the resource has a
1382 * name ending with "{@code .class}", this method will only find resources in
1383 * packages of named modules when the package is {@link Module#isOpen(String)
1384 * opened} unconditionally (even if the caller of this method is in the
1385 * same module as the resource). </p>
1386 *
1387 * @implSpec The default implementation will first search the parent class
1388 * loader for the resource; if the parent is {@code null} the path of the
1389 * class loader built into the virtual machine is searched. If not found,
1390 * this method will invoke {@link #findResource(String)} to find the resource.
1391 *
1392 * @apiNote Where several modules are defined to the same class loader,
1393 * and where more than one module contains a resource with the given name,
1394 * then the ordering that modules are searched is not specified and may be
1395 * very unpredictable.
1396 * When overriding this method it is recommended that an implementation
1397 * ensures that any delegation is consistent with the {@link
1398 * #getResources(java.lang.String) getResources(String)} method.
1399 *
1400 * @param name
1401 * The resource name
1402 *
1403 * @return {@code URL} object for reading the resource; {@code null} if
1404 * the resource could not be found, a {@code URL} could not be
1405 * constructed to locate the resource, the resource is in a package
1406 * that is not opened unconditionally, or access to the resource is
1407 * denied by the security manager.
1408 *
1409 * @throws NullPointerException If {@code name} is {@code null}
1410 *
1411 * @since 1.1
1412 * @revised 9
1413 * @spec JPMS
1414 */
1415 public URL getResource(String name) {
1416 Objects.requireNonNull(name);
1417 URL url;
1418 if (parent != null) {
1419 url = parent.getResource(name);
1420 } else {
1421 url = BootLoader.findResource(name);
1422 }
1423 if (url == null) {
1424 url = findResource(name);
1425 }
1426 return url;
1427 }
1428
1429 /**
1430 * Finds all the resources with the given name. A resource is some data
1431 * (images, audio, text, etc) that can be accessed by class code in a way
1432 * that is independent of the location of the code.
1433 *
1434 * <p> The name of a resource is a {@code /}-separated path name that
1435 * identifies the resource. </p>
1436 *
1437 * <p> Resources in named modules are subject to the encapsulation rules
1438 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1439 * Additionally, and except for the special case where the resource has a
1440 * name ending with "{@code .class}", this method will only find resources in
1441 * packages of named modules when the package is {@link Module#isOpen(String)
1442 * opened} unconditionally (even if the caller of this method is in the
1443 * same module as the resource). </p>
1444 *
1445 * @implSpec The default implementation will first search the parent class
1446 * loader for the resource; if the parent is {@code null} the path of the
1447 * class loader built into the virtual machine is searched. It then
1448 * invokes {@link #findResources(String)} to find the resources with the
1449 * name in this class loader. It returns an enumeration whose elements
1450 * are the URLs found by searching the parent class loader followed by
1451 * the elements found with {@code findResources}.
1452 *
1453 * @apiNote Where several modules are defined to the same class loader,
1454 * and where more than one module contains a resource with the given name,
1455 * then the ordering is not specified and may be very unpredictable.
1456 * When overriding this method it is recommended that an
1457 * implementation ensures that any delegation is consistent with the {@link
1458 * #getResource(java.lang.String) getResource(String)} method. This should
1459 * ensure that the first element returned by the Enumeration's
1460 * {@code nextElement} method is the same resource that the
1461 * {@code getResource(String)} method would return.
1462 *
1463 * @param name
1464 * The resource name
1465 *
1466 * @return An enumeration of {@link java.net.URL URL} objects for the
1467 * resource. If no resources could be found, the enumeration will
1468 * be empty. Resources for which a {@code URL} cannot be
1469 * constructed, are in a package that is not opened
1470 * unconditionally, or access to the resource is denied by the
1471 * security manager, are not returned in the enumeration.
1472 *
1473 * @throws IOException
1474 * If I/O errors occur
1475 * @throws NullPointerException If {@code name} is {@code null}
1476 *
1477 * @since 1.2
1478 * @revised 9
1479 * @spec JPMS
1480 */
1481 public Enumeration<URL> getResources(String name) throws IOException {
1482 Objects.requireNonNull(name);
1483 @SuppressWarnings("unchecked")
1484 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1485 if (parent != null) {
1486 tmp[0] = parent.getResources(name);
1487 } else {
1488 tmp[0] = BootLoader.findResources(name);
1489 }
1490 tmp[1] = findResources(name);
1491
1492 return new CompoundEnumeration<>(tmp);
1493 }
1494
1495 /**
1496 * Returns a stream whose elements are the URLs of all the resources with
1497 * the given name. A resource is some data (images, audio, text, etc) that
1498 * can be accessed by class code in a way that is independent of the
1499 * location of the code.
1500 *
1501 * <p> The name of a resource is a {@code /}-separated path name that
1502 * identifies the resource.
1503 *
1504 * <p> The resources will be located when the returned stream is evaluated.
1505 * If the evaluation results in an {@code IOException} then the I/O
1506 * exception is wrapped in an {@link UncheckedIOException} that is then
1507 * thrown.
1508 *
1509 * <p> Resources in named modules are subject to the encapsulation rules
1510 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1511 * Additionally, and except for the special case where the resource has a
1512 * name ending with "{@code .class}", this method will only find resources in
1513 * packages of named modules when the package is {@link Module#isOpen(String)
1514 * opened} unconditionally (even if the caller of this method is in the
1515 * same module as the resource). </p>
1516 *
1517 * @implSpec The default implementation invokes {@link #getResources(String)
1518 * getResources} to find all the resources with the given name and returns
1519 * a stream with the elements in the enumeration as the source.
1520 *
1521 * @apiNote When overriding this method it is recommended that an
1522 * implementation ensures that any delegation is consistent with the {@link
1523 * #getResource(java.lang.String) getResource(String)} method. This should
1524 * ensure that the first element returned by the stream is the same
1525 * resource that the {@code getResource(String)} method would return.
1526 *
1527 * @param name
1528 * The resource name
1529 *
1530 * @return A stream of resource {@link java.net.URL URL} objects. If no
1531 * resources could be found, the stream will be empty. Resources
1532 * for which a {@code URL} cannot be constructed, are in a package
1533 * that is not opened unconditionally, or access to the resource
1534 * is denied by the security manager, will not be in the stream.
1535 *
1536 * @throws NullPointerException If {@code name} is {@code null}
1537 *
1538 * @since 9
1539 */
1540 public Stream<URL> resources(String name) {
1541 Objects.requireNonNull(name);
1542 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
1543 Supplier<Spliterator<URL>> si = () -> {
1544 try {
1545 return Spliterators.spliteratorUnknownSize(
1546 getResources(name).asIterator(), characteristics);
1547 } catch (IOException e) {
1548 throw new UncheckedIOException(e);
1549 }
1550 };
1551 return StreamSupport.stream(si, characteristics, false);
1552 }
1553
1554 /**
1555 * Finds the resource with the given name. Class loader implementations
1556 * should override this method.
1557 *
1558 * <p> For resources in named modules then the method must implement the
1559 * rules for encapsulation specified in the {@code Module} {@link
1560 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1561 * it must not find non-"{@code .class}" resources in packages of named
1562 * modules unless the package is {@link Module#isOpen(String) opened}
1563 * unconditionally. </p>
1564 *
1565 * @implSpec The default implementation returns {@code null}.
1566 *
1567 * @param name
1568 * The resource name
1569 *
1570 * @return {@code URL} object for reading the resource; {@code null} if
1571 * the resource could not be found, a {@code URL} could not be
1572 * constructed to locate the resource, the resource is in a package
1573 * that is not opened unconditionally, or access to the resource is
1574 * denied by the security manager.
1575 *
1576 * @since 1.2
1577 * @revised 9
1578 * @spec JPMS
1579 */
1580 protected URL findResource(String name) {
1581 return null;
1582 }
1583
1584 /**
1585 * Returns an enumeration of {@link java.net.URL URL} objects
1586 * representing all the resources with the given name. Class loader
1587 * implementations should override this method.
1588 *
1589 * <p> For resources in named modules then the method must implement the
1590 * rules for encapsulation specified in the {@code Module} {@link
1591 * Module#getResourceAsStream getResourceAsStream} method. Additionally,
1592 * it must not find non-"{@code .class}" resources in packages of named
1593 * modules unless the package is {@link Module#isOpen(String) opened}
1594 * unconditionally. </p>
1595 *
1596 * @implSpec The default implementation returns an enumeration that
1597 * contains no elements.
1598 *
1599 * @param name
1600 * The resource name
1601 *
1602 * @return An enumeration of {@link java.net.URL URL} objects for
1603 * the resource. If no resources could be found, the enumeration
1604 * will be empty. Resources for which a {@code URL} cannot be
1605 * constructed, are in a package that is not opened unconditionally,
1606 * or access to the resource is denied by the security manager,
1607 * are not returned in the enumeration.
1608 *
1609 * @throws IOException
1610 * If I/O errors occur
1611 *
1612 * @since 1.2
1613 * @revised 9
1614 * @spec JPMS
1615 */
1616 protected Enumeration<URL> findResources(String name) throws IOException {
1617 return Collections.emptyEnumeration();
1618 }
1619
1620 /**
1621 * Registers the caller as
1622 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
1623 * The registration succeeds if and only if all of the following
1624 * conditions are met:
1625 * <ol>
1626 * <li> no instance of the caller has been created</li>
1627 * <li> all of the super classes (except class Object) of the caller are
1628 * registered as parallel capable</li>
1629 * </ol>
1630 * <p>Note that once a class loader is registered as parallel capable, there
1631 * is no way to change it back.</p>
1632 *
1633 * @return {@code true} if the caller is successfully registered as
1634 * parallel capable and {@code false} if otherwise.
1635 *
1636 * @see #isRegisteredAsParallelCapable()
1637 *
1638 * @since 1.7
1639 */
1640 @CallerSensitive
1641 protected static boolean registerAsParallelCapable() {
1642 Class<? extends ClassLoader> callerClass =
1643 Reflection.getCallerClass().asSubclass(ClassLoader.class);
1644 return ParallelLoaders.register(callerClass);
1645 }
1646
1647 /**
1648 * Returns {@code true} if this class loader is registered as
1649 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
1650 * {@code false}.
1651 *
1652 * @return {@code true} if this class loader is parallel capable,
1653 * otherwise {@code false}.
1654 *
1655 * @see #registerAsParallelCapable()
1656 *
1657 * @since 9
1658 */
1659 public final boolean isRegisteredAsParallelCapable() {
1660 return ParallelLoaders.isRegistered(this.getClass());
1661 }
1662
1663 /**
1664 * Find a resource of the specified name from the search path used to load
1665 * classes. This method locates the resource through the system class
1666 * loader (see {@link #getSystemClassLoader()}).
1667 *
1668 * <p> Resources in named modules are subject to the encapsulation rules
1669 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1670 * Additionally, and except for the special case where the resource has a
1671 * name ending with "{@code .class}", this method will only find resources in
1672 * packages of named modules when the package is {@link Module#isOpen(String)
1673 * opened} unconditionally. </p>
1674 *
1675 * @param name
1676 * The resource name
1677 *
1678 * @return A {@link java.net.URL URL} to the resource; {@code
1679 * null} if the resource could not be found, a URL could not be
1680 * constructed to locate the resource, the resource is in a package
1681 * that is not opened unconditionally or access to the resource is
1682 * denied by the security manager.
1683 *
1684 * @since 1.1
1685 * @revised 9
1686 * @spec JPMS
1687 */
1688 public static URL getSystemResource(String name) {
1689 return getSystemClassLoader().getResource(name);
1690 }
1691
1692 /**
1693 * Finds all resources of the specified name from the search path used to
1694 * load classes. The resources thus found are returned as an
1695 * {@link java.util.Enumeration Enumeration} of {@link
1696 * java.net.URL URL} objects.
1697 *
1698 * <p> The search order is described in the documentation for {@link
1699 * #getSystemResource(String)}. </p>
1700 *
1701 * <p> Resources in named modules are subject to the encapsulation rules
1702 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1703 * Additionally, and except for the special case where the resource has a
1704 * name ending with "{@code .class}", this method will only find resources in
1705 * packages of named modules when the package is {@link Module#isOpen(String)
1706 * opened} unconditionally. </p>
1707 *
1708 * @param name
1709 * The resource name
1710 *
1711 * @return An enumeration of {@link java.net.URL URL} objects for
1712 * the resource. If no resources could be found, the enumeration
1713 * will be empty. Resources for which a {@code URL} cannot be
1714 * constructed, are in a package that is not opened unconditionally,
1715 * or access to the resource is denied by the security manager,
1716 * are not returned in the enumeration.
1717 *
1718 * @throws IOException
1719 * If I/O errors occur
1720 *
1721 * @since 1.2
1722 * @revised 9
1723 * @spec JPMS
1724 */
1725 public static Enumeration<URL> getSystemResources(String name)
1726 throws IOException
1727 {
1728 return getSystemClassLoader().getResources(name);
1729 }
1730
1731 /**
1732 * Returns an input stream for reading the specified resource.
1733 *
1734 * <p> The search order is described in the documentation for {@link
1735 * #getResource(String)}. </p>
1736 *
1737 * <p> Resources in named modules are subject to the encapsulation rules
1738 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1739 * Additionally, and except for the special case where the resource has a
1740 * name ending with "{@code .class}", this method will only find resources in
1741 * packages of named modules when the package is {@link Module#isOpen(String)
1742 * opened} unconditionally. </p>
1743 *
1744 * @param name
1745 * The resource name
1746 *
1747 * @return An input stream for reading the resource; {@code null} if the
1748 * resource could not be found, the resource is in a package that
1749 * is not opened unconditionally, or access to the resource is
1750 * denied by the security manager.
1751 *
1752 * @throws NullPointerException If {@code name} is {@code null}
1753 *
1754 * @since 1.1
1755 * @revised 9
1756 * @spec JPMS
1757 */
1758 public InputStream getResourceAsStream(String name) {
1759 Objects.requireNonNull(name);
1760 URL url = getResource(name);
1761 try {
1762 return url != null ? url.openStream() : null;
1763 } catch (IOException e) {
1764 return null;
1765 }
1766 }
1767
1768 /**
1769 * Open for reading, a resource of the specified name from the search path
1770 * used to load classes. This method locates the resource through the
1771 * system class loader (see {@link #getSystemClassLoader()}).
1772 *
1773 * <p> Resources in named modules are subject to the encapsulation rules
1774 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
1775 * Additionally, and except for the special case where the resource has a
1776 * name ending with "{@code .class}", this method will only find resources in
1777 * packages of named modules when the package is {@link Module#isOpen(String)
1778 * opened} unconditionally. </p>
1779 *
1780 * @param name
1781 * The resource name
1782 *
1783 * @return An input stream for reading the resource; {@code null} if the
1784 * resource could not be found, the resource is in a package that
1785 * is not opened unconditionally, or access to the resource is
1786 * denied by the security manager.
1787 *
1788 * @since 1.1
1789 * @revised 9
1790 * @spec JPMS
1791 */
1792 public static InputStream getSystemResourceAsStream(String name) {
1793 URL url = getSystemResource(name);
1794 try {
1795 return url != null ? url.openStream() : null;
1796 } catch (IOException e) {
1797 return null;
1798 }
1799 }
1800
1801
1802 // -- Hierarchy --
1803
1804 /**
1805 * Returns the parent class loader for delegation. Some implementations may
1806 * use {@code null} to represent the bootstrap class loader. This method
1807 * will return {@code null} in such implementations if this class loader's
1808 * parent is the bootstrap class loader.
1809 *
1810 * @return The parent {@code ClassLoader}
1811 *
1812 * @throws SecurityException
1813 * If a security manager is present, and the caller's class loader
1814 * is not {@code null} and is not an ancestor of this class loader,
1815 * and the caller does not have the
1816 * {@link RuntimePermission}{@code ("getClassLoader")}
1817 *
1818 * @since 1.2
1819 */
1820 @CallerSensitive
1821 public final ClassLoader getParent() {
1822 if (parent == null)
1823 return null;
1824 SecurityManager sm = System.getSecurityManager();
1825 if (sm != null) {
1826 // Check access to the parent class loader
1827 // If the caller's class loader is same as this class loader,
1828 // permission check is performed.
1829 checkClassLoaderPermission(parent, Reflection.getCallerClass());
1830 }
1831 return parent;
1832 }
1833
1834 /**
1835 * Returns the unnamed {@code Module} for this class loader.
1836 *
1837 * @return The unnamed Module for this class loader
1838 *
1839 * @see Module#isNamed()
1840 * @since 9
1841 * @spec JPMS
1842 */
1843 public final Module getUnnamedModule() {
1844 return unnamedModule;
1845 }
1846
1847 /**
1848 * Returns the platform class loader. All
1849 * <a href="#builtinLoaders">platform classes</a> are visible to
1850 * the platform class loader.
1851 *
1852 * @implNote The name of the builtin platform class loader is
1853 * {@code "platform"}.
1854 *
1855 * @return The platform {@code ClassLoader}.
1856 *
1857 * @throws SecurityException
1858 * If a security manager is present, and the caller's class loader is
1859 * not {@code null}, and the caller's class loader is not the same
1860 * as or an ancestor of the platform class loader,
1861 * and the caller does not have the
1862 * {@link RuntimePermission}{@code ("getClassLoader")}
1863 *
1864 * @since 9
1865 * @spec JPMS
1866 */
1867 @CallerSensitive
1868 public static ClassLoader getPlatformClassLoader() {
1869 SecurityManager sm = System.getSecurityManager();
1870 ClassLoader loader = getBuiltinPlatformClassLoader();
1871 if (sm != null) {
1872 checkClassLoaderPermission(loader, Reflection.getCallerClass());
1873 }
1874 return loader;
1875 }
1876
1877 /**
1878 * Returns the system class loader. This is the default
1879 * delegation parent for new {@code ClassLoader} instances, and is
1880 * typically the class loader used to start the application.
1881 *
1882 * <p> This method is first invoked early in the runtime's startup
1883 * sequence, at which point it creates the system class loader. This
1884 * class loader will be the context class loader for the main application
1885 * thread (for example, the thread that invokes the {@code main} method of
1886 * the main class).
1887 *
1888 * <p> The default system class loader is an implementation-dependent
1889 * instance of this class.
1890 *
1891 * <p> If the system property "{@systemProperty java.system.class.loader}"
1892 * is defined when this method is first invoked then the value of that
1893 * property is taken to be the name of a class that will be returned as the
1894 * system class loader. The class is loaded using the default system class
1895 * loader and must define a public constructor that takes a single parameter
1896 * of type {@code ClassLoader} which is used as the delegation parent. An
1897 * instance is then created using this constructor with the default system
1898 * class loader as the parameter. The resulting class loader is defined
1899 * to be the system class loader. During construction, the class loader
1900 * should take great care to avoid calling {@code getSystemClassLoader()}.
1901 * If circular initialization of the system class loader is detected then
1902 * an {@code IllegalStateException} is thrown.
1903 *
1904 * @implNote The system property to override the system class loader is not
1905 * examined until the VM is almost fully initialized. Code that executes
1906 * this method during startup should take care not to cache the return
1907 * value until the system is fully initialized.
1908 *
1909 * <p> The name of the built-in system class loader is {@code "app"}.
1910 * The system property "{@code java.class.path}" is read during early
1911 * initialization of the VM to determine the class path.
1912 * An empty value of "{@code java.class.path}" property is interpreted
1913 * differently depending on whether the initial module (the module
1914 * containing the main class) is named or unnamed:
1915 * If named, the built-in system class loader will have no class path and
1916 * will search for classes and resources using the application module path;
1917 * otherwise, if unnamed, it will set the class path to the current
1918 * working directory.
1919 *
1920 * <p> JAR files on the class path may contain a {@code Class-Path} manifest
1921 * attribute to specify dependent JAR files to be included in the class path.
1922 * {@code Class-Path} entries must meet certain conditions for validity (see
1923 * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute">
1924 * JAR File Specification</a> for details). Invalid {@code Class-Path}
1925 * entries are ignored. For debugging purposes, ignored entries can be
1926 * printed to the console if the
1927 * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system
1928 * property is set to {@code true}.
1929 *
1930 * @return The system {@code ClassLoader}
1931 *
1932 * @throws SecurityException
1933 * If a security manager is present, and the caller's class loader
1934 * is not {@code null} and is not the same as or an ancestor of the
1935 * system class loader, and the caller does not have the
1936 * {@link RuntimePermission}{@code ("getClassLoader")}
1937 *
1938 * @throws IllegalStateException
1939 * If invoked recursively during the construction of the class
1940 * loader specified by the "{@code java.system.class.loader}"
1941 * property.
1942 *
1943 * @throws Error
1944 * If the system property "{@code java.system.class.loader}"
1945 * is defined but the named class could not be loaded, the
1946 * provider class does not define the required constructor, or an
1947 * exception is thrown by that constructor when it is invoked. The
1948 * underlying cause of the error can be retrieved via the
1949 * {@link Throwable#getCause()} method.
1950 *
1951 * @revised 1.4
1952 * @revised 9
1953 * @spec JPMS
1954 */
1955 @CallerSensitive
1956 public static ClassLoader getSystemClassLoader() {
1957 switch (VM.initLevel()) {
1958 case 0:
1959 case 1:
1960 case 2:
1961 // the system class loader is the built-in app class loader during startup
1962 return getBuiltinAppClassLoader();
1963 case 3:
1964 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
1965 throw new IllegalStateException(msg);
1966 default:
1967 // system fully initialized
1968 assert VM.isBooted() && scl != null;
1969 SecurityManager sm = System.getSecurityManager();
1970 if (sm != null) {
1971 checkClassLoaderPermission(scl, Reflection.getCallerClass());
1972 }
1973 return scl;
1974 }
1975 }
1976
1977 static ClassLoader getBuiltinPlatformClassLoader() {
1978 return ClassLoaders.platformClassLoader();
1979 }
1980
1981 static ClassLoader getBuiltinAppClassLoader() {
1982 return ClassLoaders.appClassLoader();
1983 }
1984
1985 /*
1986 * Initialize the system class loader that may be a custom class on the
1987 * application class path or application module path.
1988 *
1989 * @see java.lang.System#initPhase3
1990 */
1991 static synchronized ClassLoader initSystemClassLoader() {
1992 if (VM.initLevel() != 3) {
1993 throw new InternalError("system class loader cannot be set at initLevel " +
1994 VM.initLevel());
1995 }
1996
1997 // detect recursive initialization
1998 if (scl != null) {
1999 throw new IllegalStateException("recursive invocation");
2000 }
2001
2002 ClassLoader builtinLoader = getBuiltinAppClassLoader();
2003
2004 // All are privileged frames. No need to call doPrivileged.
2005 String cn = System.getProperty("java.system.class.loader");
2006 if (cn != null) {
2007 try {
2008 // custom class loader is only supported to be loaded from unnamed module
2009 Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
2010 .getDeclaredConstructor(ClassLoader.class);
2011 scl = (ClassLoader) ctor.newInstance(builtinLoader);
2012 } catch (Exception e) {
2013 Throwable cause = e;
2014 if (e instanceof InvocationTargetException) {
2015 cause = e.getCause();
2016 if (cause instanceof Error) {
2017 throw (Error) cause;
2018 }
2019 }
2020 if (cause instanceof RuntimeException) {
2021 throw (RuntimeException) cause;
2022 }
2023 throw new Error(cause.getMessage(), cause);
2024 }
2025 } else {
2026 scl = builtinLoader;
2027 }
2028 return scl;
2029 }
2030
2031 /*
2032 * Initialize default paths for native libraries search.
2033 * Must be done early as JDK may load libraries during bootstrap.
2034 *
2035 * @see java.lang.System#initPhase1
2036 */
2037 static void initLibraryPaths() {
2038 usr_paths = initializePath("java.library.path");
2039 sys_paths = initializePath("sun.boot.library.path");
2040 }
2041
2042 // Returns true if the specified class loader can be found in this class
2043 // loader's delegation chain.
2044 boolean isAncestor(ClassLoader cl) {
2045 ClassLoader acl = this;
2046 do {
2047 acl = acl.parent;
2048 if (cl == acl) {
2049 return true;
2050 }
2051 } while (acl != null);
2052 return false;
2053 }
2054
2055 // Tests if class loader access requires "getClassLoader" permission
2056 // check. A class loader 'from' can access class loader 'to' if
2057 // class loader 'from' is same as class loader 'to' or an ancestor
2058 // of 'to'. The class loader in a system domain can access
2059 // any class loader.
2060 private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
2061 ClassLoader to)
2062 {
2063 if (from == to)
2064 return false;
2065
2066 if (from == null)
2067 return false;
2068
2069 return !to.isAncestor(from);
2070 }
2071
2072 // Returns the class's class loader, or null if none.
2073 static ClassLoader getClassLoader(Class<?> caller) {
2074 // This can be null if the VM is requesting it
2075 if (caller == null) {
2076 return null;
2077 }
2078 // Circumvent security check since this is package-private
2079 return caller.getClassLoader0();
2080 }
2081
2082 /*
2083 * Checks RuntimePermission("getClassLoader") permission
2084 * if caller's class loader is not null and caller's class loader
2085 * is not the same as or an ancestor of the given cl argument.
2086 */
2087 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
2088 SecurityManager sm = System.getSecurityManager();
2089 if (sm != null) {
2090 // caller can be null if the VM is requesting it
2091 ClassLoader ccl = getClassLoader(caller);
2092 if (needsClassLoaderPermissionCheck(ccl, cl)) {
2093 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
2094 }
2095 }
2096 }
2097
2098 // The system class loader
2099 // @GuardedBy("ClassLoader.class")
2100 private static volatile ClassLoader scl;
2101
2102 // -- Package --
2103
2104 /**
2105 * Define a Package of the given Class object.
2106 *
2107 * If the given class represents an array type, a primitive type or void,
2108 * this method returns {@code null}.
2109 *
2110 * This method does not throw IllegalArgumentException.
2111 */
2112 Package definePackage(Class<?> c) {
2113 if (c.isPrimitive() || c.isArray()) {
2114 return null;
2115 }
2116
2117 return definePackage(c.getPackageName(), c.getModule());
2118 }
2119
2120 /**
2121 * Defines a Package of the given name and module
2122 *
2123 * This method does not throw IllegalArgumentException.
2124 *
2125 * @param name package name
2126 * @param m module
2127 */
2128 Package definePackage(String name, Module m) {
2129 if (name.isEmpty() && m.isNamed()) {
2130 throw new InternalError("unnamed package in " + m);
2131 }
2132
2133 // check if Package object is already defined
2134 NamedPackage pkg = packages.get(name);
2135 if (pkg instanceof Package)
2136 return (Package)pkg;
2137
2138 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
2139 }
2140
2141 /*
2142 * Returns a Package object for the named package
2143 */
2144 private Package toPackage(String name, NamedPackage p, Module m) {
2145 // define Package object if the named package is not yet defined
2146 if (p == null)
2147 return NamedPackage.toPackage(name, m);
2148
2149 // otherwise, replace the NamedPackage object with Package object
2150 if (p instanceof Package)
2151 return (Package)p;
2152
2153 return NamedPackage.toPackage(p.packageName(), p.module());
2154 }
2155
2156 /**
2157 * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}.
2158 * <p>
2159 * <a href="#binary-name">Package names</a> must be unique within a class loader and
2160 * cannot be redefined or changed once created.
2161 * <p>
2162 * If a class loader wishes to define a package with specific properties,
2163 * such as version information, then the class loader should call this
2164 * {@code definePackage} method before calling {@code defineClass}.
2165 * Otherwise, the
2166 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
2167 * method will define a package in this class loader corresponding to the package
2168 * of the newly defined class; the properties of this defined package are
2169 * specified by {@link Package}.
2170 *
2171 * @apiNote
2172 * A class loader that wishes to define a package for classes in a JAR
2173 * typically uses the specification and implementation titles, versions, and
2174 * vendors from the JAR's manifest. If the package is specified as
2175 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
2176 * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
2177 * If classes of package {@code 'p'} defined by this class loader
2178 * are loaded from multiple JARs, the {@code Package} object may contain
2179 * different information depending on the first class of package {@code 'p'}
2180 * defined and which JAR's manifest is read first to explicitly define
2181 * package {@code 'p'}.
2182 *
2183 * <p> It is strongly recommended that a class loader does not call this
2184 * method to explicitly define packages in <em>named modules</em>; instead,
2185 * the package will be automatically defined when a class is {@linkplain
2186 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
2187 * If it is desirable to define {@code Package} explicitly, it should ensure
2188 * that all packages in a named module are defined with the properties
2189 * specified by {@link Package}. Otherwise, some {@code Package} objects
2190 * in a named module may be for example sealed with different seal base.
2191 *
2192 * @param name
2193 * The <a href="#binary-name">package name</a>
2194 *
2195 * @param specTitle
2196 * The specification title
2197 *
2198 * @param specVersion
2199 * The specification version
2200 *
2201 * @param specVendor
2202 * The specification vendor
2203 *
2204 * @param implTitle
2205 * The implementation title
2206 *
2207 * @param implVersion
2208 * The implementation version
2209 *
2210 * @param implVendor
2211 * The implementation vendor
2212 *
2213 * @param sealBase
2214 * If not {@code null}, then this package is sealed with
2215 * respect to the given code source {@link java.net.URL URL}
2216 * object. Otherwise, the package is not sealed.
2217 *
2218 * @return The newly defined {@code Package} object
2219 *
2220 * @throws NullPointerException
2221 * if {@code name} is {@code null}.
2222 *
2223 * @throws IllegalArgumentException
2224 * if a package of the given {@code name} is already
2225 * defined by this class loader
2226 *
2227 *
2228 * @since 1.2
2229 * @revised 9
2230 * @spec JPMS
2231 *
2232 * @jvms 5.3 Creation and Loading
2233 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
2234 * The JAR File Specification: Package Sealing</a>
2235 */
2236 protected Package definePackage(String name, String specTitle,
2237 String specVersion, String specVendor,
2238 String implTitle, String implVersion,
2239 String implVendor, URL sealBase)
2240 {
2241 Objects.requireNonNull(name);
2242
2243 // definePackage is not final and may be overridden by custom class loader
2244 Package p = new Package(name, specTitle, specVersion, specVendor,
2245 implTitle, implVersion, implVendor,
2246 sealBase, this);
2247
2248 if (packages.putIfAbsent(name, p) != null)
2249 throw new IllegalArgumentException(name);
2250
2251 return p;
2252 }
2253
2254 /**
2255 * Returns a {@code Package} of the given <a href="#binary-name">name</a> that
2256 * has been defined by this class loader.
2257 *
2258 * @param name The <a href="#binary-name">package name</a>
2259 *
2260 * @return The {@code Package} of the given name that has been defined
2261 * by this class loader, or {@code null} if not found
2262 *
2263 * @throws NullPointerException
2264 * if {@code name} is {@code null}.
2265 *
2266 * @jvms 5.3 Creation and Loading
2267 *
2268 * @since 9
2269 * @spec JPMS
2270 */
2271 public final Package getDefinedPackage(String name) {
2272 Objects.requireNonNull(name, "name cannot be null");
2273
2274 NamedPackage p = packages.get(name);
2275 if (p == null)
2276 return null;
2277
2278 return definePackage(name, p.module());
2279 }
2280
2281 /**
2282 * Returns all of the {@code Package}s that have been defined by
2283 * this class loader. The returned array has no duplicated {@code Package}s
2284 * of the same name.
2285 *
2286 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
2287 * for consistency with the existing {@link #getPackages} method.
2288 *
2289 * @return The array of {@code Package} objects that have been defined by
2290 * this class loader; or an zero length array if no package has been
2291 * defined by this class loader.
2292 *
2293 * @jvms 5.3 Creation and Loading
2294 *
2295 * @since 9
2296 * @spec JPMS
2297 */
2298 public final Package[] getDefinedPackages() {
2299 return packages().toArray(Package[]::new);
2300 }
2301
2302 /**
2303 * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors.
2304 * <p>
2305 * If this class loader defines a {@code Package} of the given name,
2306 * the {@code Package} is returned. Otherwise, the ancestors of
2307 * this class loader are searched recursively (parent by parent)
2308 * for a {@code Package} of the given name.
2309 *
2310 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2311 * may delegate to the application class loader but the application class
2312 * loader is not its ancestor. When invoked on the platform class loader,
2313 * this method will not find packages defined to the application
2314 * class loader.
2315 *
2316 * @param name
2317 * The <a href="#binary-name">package name</a>
2318 *
2319 * @return The {@code Package} of the given name that has been defined by
2320 * this class loader or its ancestors, or {@code null} if not found.
2321 *
2322 * @throws NullPointerException
2323 * if {@code name} is {@code null}.
2324 *
2325 * @deprecated
2326 * If multiple class loaders delegate to each other and define classes
2327 * with the same package name, and one such loader relies on the lookup
2328 * behavior of {@code getPackage} to return a {@code Package} from
2329 * a parent loader, then the properties exposed by the {@code Package}
2330 * may not be as expected in the rest of the program.
2331 * For example, the {@code Package} will only expose annotations from the
2332 * {@code package-info.class} file defined by the parent loader, even if
2333 * annotations exist in a {@code package-info.class} file defined by
2334 * a child loader. A more robust approach is to use the
2335 * {@link ClassLoader#getDefinedPackage} method which returns
2336 * a {@code Package} for the specified class loader.
2337 *
2338 * @see ClassLoader#getDefinedPackage(String)
2339 *
2340 * @since 1.2
2341 * @revised 9
2342 * @spec JPMS
2343 */
2344 @Deprecated(since="9")
2345 protected Package getPackage(String name) {
2346 Package pkg = getDefinedPackage(name);
2347 if (pkg == null) {
2348 if (parent != null) {
2349 pkg = parent.getPackage(name);
2350 } else {
2351 pkg = BootLoader.getDefinedPackage(name);
2352 }
2353 }
2354 return pkg;
2355 }
2356
2357 /**
2358 * Returns all of the {@code Package}s that have been defined by
2359 * this class loader and its ancestors. The returned array may contain
2360 * more than one {@code Package} object of the same package name, each
2361 * defined by a different class loader in the class loader hierarchy.
2362 *
2363 * @apiNote The {@link #getPlatformClassLoader() platform class loader}
2364 * may delegate to the application class loader. In other words,
2365 * packages in modules defined to the application class loader may be
2366 * visible to the platform class loader. On the other hand,
2367 * the application class loader is not its ancestor and hence
2368 * when invoked on the platform class loader, this method will not
2369 * return any packages defined to the application class loader.
2370 *
2371 * @return The array of {@code Package} objects that have been defined by
2372 * this class loader and its ancestors
2373 *
2374 * @see ClassLoader#getDefinedPackages()
2375 *
2376 * @since 1.2
2377 * @revised 9
2378 * @spec JPMS
2379 */
2380 protected Package[] getPackages() {
2381 Stream<Package> pkgs = packages();
2382 ClassLoader ld = parent;
2383 while (ld != null) {
2384 pkgs = Stream.concat(ld.packages(), pkgs);
2385 ld = ld.parent;
2386 }
2387 return Stream.concat(BootLoader.packages(), pkgs)
2388 .toArray(Package[]::new);
2389 }
2390
2391
2392
2393 // package-private
2394
2395 /**
2396 * Returns a stream of Packages defined in this class loader
2397 */
2398 Stream<Package> packages() {
2399 return packages.values().stream()
2400 .map(p -> definePackage(p.packageName(), p.module()));
2401 }
2402
2403 // -- Native library access --
2404
2405 /**
2406 * Returns the absolute path name of a native library. The VM invokes this
2407 * method to locate the native libraries that belong to classes loaded with
2408 * this class loader. If this method returns {@code null}, the VM
2409 * searches the library along the path specified as the
2410 * "{@code java.library.path}" property.
2411 *
2412 * @param libname
2413 * The library name
2414 *
2415 * @return The absolute path of the native library
2416 *
2417 * @see System#loadLibrary(String)
2418 * @see System#mapLibraryName(String)
2419 *
2420 * @since 1.2
2421 */
2422 protected String findLibrary(String libname) {
2423 return null;
2424 }
2425
2426 /**
2427 * The inner class NativeLibrary denotes a loaded native library instance.
2428 * Every classloader contains a vector of loaded native libraries in the
2429 * private field {@code nativeLibraries}. The native libraries loaded
2430 * into the system are entered into the {@code systemNativeLibraries}
2431 * vector.
2432 *
2433 * <p> Every native library requires a particular version of JNI. This is
2434 * denoted by the private {@code jniVersion} field. This field is set by
2435 * the VM when it loads the library, and used by the VM to pass the correct
2436 * version of JNI to the native methods. </p>
2437 *
2438 * @see ClassLoader
2439 * @since 1.2
2440 */
2441 static class NativeLibrary {
2442 // the class from which the library is loaded, also indicates
2443 // the loader this native library belongs.
2444 final Class<?> fromClass;
2445 // the canonicalized name of the native library.
2446 // or static library name
2447 final String name;
2448 // Indicates if the native library is linked into the VM
2449 final boolean isBuiltin;
2450
2451 // opaque handle to native library, used in native code.
2452 long handle;
2453 // the version of JNI environment the native library requires.
2454 int jniVersion;
2455
2456 native boolean load0(String name, boolean isBuiltin);
2457
2458 native long findEntry(String name);
2459
2460 NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
2461 this.name = name;
2462 this.fromClass = fromClass;
2463 this.isBuiltin = isBuiltin;
2464 }
2465
2466 /*
2467 * Loads the native library and registers for cleanup when its
2468 * associated class loader is unloaded
2469 */
2470 boolean load() {
2471 if (handle != 0) {
2472 throw new InternalError("Native library " + name + " has been loaded");
2473 }
2474
2475 if (!load0(name, isBuiltin)) return false;
2476
2477 // register the class loader for cleanup when unloaded
2478 // builtin class loaders are never unloaded
2479 ClassLoader loader = fromClass.getClassLoader();
2480 if (loader != null &&
2481 loader != getBuiltinPlatformClassLoader() &&
2482 loader != getBuiltinAppClassLoader()) {
2483 CleanerFactory.cleaner().register(loader,
2484 new Unloader(name, handle, isBuiltin));
2485 }
2486 return true;
2487 }
2488
2489 static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
2490 ClassLoader loader =
2491 fromClass == null ? null : fromClass.getClassLoader();
2492
2493 synchronized (loadedLibraryNames) {
2494 Map<String, NativeLibrary> libs =
2495 loader != null ? loader.nativeLibraries() : systemNativeLibraries();
2496 if (libs.containsKey(name)) {
2497 return true;
2498 }
2499
2500 if (loadedLibraryNames.contains(name)) {
2501 throw new UnsatisfiedLinkError("Native Library " + name +
2502 " already loaded in another classloader");
2503 }
2504
2505 /*
2506 * When a library is being loaded, JNI_OnLoad function can cause
2507 * another loadLibrary invocation that should succeed.
2508 *
2509 * We use a static stack to hold the list of libraries we are
2510 * loading because this can happen only when called by the
2511 * same thread because this block is synchronous.
2512 *
2513 * If there is a pending load operation for the library, we
2514 * immediately return success; otherwise, we raise
2515 * UnsatisfiedLinkError.
2516 */
2517 for (NativeLibrary lib : nativeLibraryContext) {
2518 if (name.equals(lib.name)) {
2519 if (loader == lib.fromClass.getClassLoader()) {
2520 return true;
2521 } else {
2522 throw new UnsatisfiedLinkError("Native Library " +
2523 name + " is being loaded in another classloader");
2524 }
2525 }
2526 }
2527 NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
2528 // load the native library
2529 nativeLibraryContext.push(lib);
2530 try {
2531 if (!lib.load()) return false;
2532 } finally {
2533 nativeLibraryContext.pop();
2534 }
2535 // register the loaded native library
2536 loadedLibraryNames.add(name);
2537 libs.put(name, lib);
2538 }
2539 return true;
2540 }
2541
2542 // Invoked in the VM to determine the context class in JNI_OnLoad
2543 // and JNI_OnUnload
2544 static Class<?> getFromClass() {
2545 return nativeLibraryContext.peek().fromClass;
2546 }
2547
2548 // native libraries being loaded
2549 static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8);
2550
2551 /*
2552 * The run() method will be invoked when this class loader becomes
2553 * phantom reachable to unload the native library.
2554 */
2555 static class Unloader implements Runnable {
2556 // This represents the context when a native library is unloaded
2557 // and getFromClass() will return null,
2558 static final NativeLibrary UNLOADER =
2559 new NativeLibrary(null, "dummy", false);
2560 final String name;
2561 final long handle;
2562 final boolean isBuiltin;
2563
2564 Unloader(String name, long handle, boolean isBuiltin) {
2565 if (handle == 0) {
2566 throw new IllegalArgumentException(
2567 "Invalid handle for native library " + name);
2568 }
2569
2570 this.name = name;
2571 this.handle = handle;
2572 this.isBuiltin = isBuiltin;
2573 }
2574
2575 @Override
2576 public void run() {
2577 synchronized (loadedLibraryNames) {
2578 /* remove the native library name */
2579 loadedLibraryNames.remove(name);
2580 nativeLibraryContext.push(UNLOADER);
2581 try {
2582 unload(name, isBuiltin, handle);
2583 } finally {
2584 nativeLibraryContext.pop();
2585 }
2586
2587 }
2588 }
2589 }
2590
2591 // JNI FindClass expects the caller class if invoked from JNI_OnLoad
2592 // and JNI_OnUnload is NativeLibrary class
2593 static native void unload(String name, boolean isBuiltin, long handle);
2594 }
2595
2596 // The paths searched for libraries
2597 private static String usr_paths[];
2598 private static String sys_paths[];
2599
2600 private static String[] initializePath(String propName) {
2601 String ldPath = System.getProperty(propName, "");
2602 int ldLen = ldPath.length();
2603 char ps = File.pathSeparatorChar;
2604 int psCount = 0;
2605
2606 if (ClassLoaderHelper.allowsQuotedPathElements &&
2607 ldPath.indexOf('\"') >= 0) {
2608 // First, remove quotes put around quoted parts of paths.
2609 // Second, use a quotation mark as a new path separator.
2610 // This will preserve any quoted old path separators.
2611 char[] buf = new char[ldLen];
2612 int bufLen = 0;
2613 for (int i = 0; i < ldLen; ++i) {
2614 char ch = ldPath.charAt(i);
2615 if (ch == '\"') {
2616 while (++i < ldLen &&
2617 (ch = ldPath.charAt(i)) != '\"') {
2618 buf[bufLen++] = ch;
2619 }
2620 } else {
2621 if (ch == ps) {
2622 psCount++;
2623 ch = '\"';
2624 }
2625 buf[bufLen++] = ch;
2626 }
2627 }
2628 ldPath = new String(buf, 0, bufLen);
2629 ldLen = bufLen;
2630 ps = '\"';
2631 } else {
2632 for (int i = ldPath.indexOf(ps); i >= 0;
2633 i = ldPath.indexOf(ps, i + 1)) {
2634 psCount++;
2635 }
2636 }
2637
2638 String[] paths = new String[psCount + 1];
2639 int pathStart = 0;
2640 for (int j = 0; j < psCount; ++j) {
2641 int pathEnd = ldPath.indexOf(ps, pathStart);
2642 paths[j] = (pathStart < pathEnd) ?
2643 ldPath.substring(pathStart, pathEnd) : ".";
2644 pathStart = pathEnd + 1;
2645 }
2646 paths[psCount] = (pathStart < ldLen) ?
2647 ldPath.substring(pathStart, ldLen) : ".";
2648 return paths;
2649 }
2650
2651 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
2652 static void loadLibrary(Class<?> fromClass, String name,
2653 boolean isAbsolute) {
2654 ClassLoader loader =
2655 (fromClass == null) ? null : fromClass.getClassLoader();
2656 assert sys_paths != null : "should be initialized at this point";
2657 assert usr_paths != null : "should be initialized at this point";
2658
2659 if (isAbsolute) {
2660 if (loadLibrary0(fromClass, new File(name))) {
2661 return;
2662 }
2663 throw new UnsatisfiedLinkError("Can't load library: " + name);
2664 }
2665 if (loader != null) {
2666 String libfilename = loader.findLibrary(name);
2667 if (libfilename != null) {
2668 File libfile = new File(libfilename);
2669 if (!libfile.isAbsolute()) {
2670 throw new UnsatisfiedLinkError(
2671 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
2672 }
2673 if (loadLibrary0(fromClass, libfile)) {
2674 return;
2675 }
2676 throw new UnsatisfiedLinkError("Can't load " + libfilename);
2677 }
2678 }
2679 for (String sys_path : sys_paths) {
2680 File libfile = new File(sys_path, System.mapLibraryName(name));
2681 if (loadLibrary0(fromClass, libfile)) {
2682 return;
2683 }
2684 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
2685 if (libfile != null && loadLibrary0(fromClass, libfile)) {
2686 return;
2687 }
2688 }
2689 if (loader != null) {
2690 for (String usr_path : usr_paths) {
2691 File libfile = new File(usr_path, System.mapLibraryName(name));
2692 if (loadLibrary0(fromClass, libfile)) {
2693 return;
2694 }
2695 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
2696 if (libfile != null && loadLibrary0(fromClass, libfile)) {
2697 return;
2698 }
2699 }
2700 }
2701 // Oops, it failed
2702 throw new UnsatisfiedLinkError("no " + name +
2703 " in java.library.path: " + Arrays.toString(usr_paths));
2704 }
2705
2706 private static native String findBuiltinLib(String name);
2707
2708 private static boolean loadLibrary0(Class<?> fromClass, final File file) {
2709 // Check to see if we're attempting to access a static library
2710 String name = findBuiltinLib(file.getName());
2711 boolean isBuiltin = (name != null);
2712 if (!isBuiltin) {
2713 name = AccessController.doPrivileged(
2714 new PrivilegedAction<>() {
2715 public String run() {
2716 try {
2717 return file.exists() ? file.getCanonicalPath() : null;
2718 } catch (IOException e) {
2719 return null;
2720 }
2721 }
2722 });
2723 if (name == null) {
2724 return false;
2725 }
2726 }
2727 return NativeLibrary.loadLibrary(fromClass, name, isBuiltin);
2728 }
2729
2730 /*
2731 * Invoked in the VM class linking code.
2732 */
2733 private static long findNative(ClassLoader loader, String entryName) {
2734 Map<String, NativeLibrary> libs =
2735 loader != null ? loader.nativeLibraries() : systemNativeLibraries();
2736 if (libs.isEmpty())
2737 return 0;
2738
2739 // the native libraries map may be updated in another thread
2740 // when a native library is being loaded. No symbol will be
2741 // searched from it yet.
2742 for (NativeLibrary lib : libs.values()) {
2743 long entry = lib.findEntry(entryName);
2744 if (entry != 0) return entry;
2745 }
2746 return 0;
2747 }
2748
2749 // All native library names we've loaded.
2750 // This also serves as the lock to obtain nativeLibraries
2751 // and write to nativeLibraryContext.
2752 private static final Set<String> loadedLibraryNames = new HashSet<>();
2753
2754 // Native libraries belonging to system classes.
2755 private static volatile Map<String, NativeLibrary> systemNativeLibraries;
2756
2757 // Native libraries associated with the class loader.
2758 private volatile Map<String, NativeLibrary> nativeLibraries;
2759
2760 /*
2761 * Returns the native libraries map associated with bootstrap class loader
2762 * This method will create the map at the first time when called.
2763 */
2764 private static Map<String, NativeLibrary> systemNativeLibraries() {
2765 Map<String, NativeLibrary> libs = systemNativeLibraries;
2766 if (libs == null) {
2767 synchronized (loadedLibraryNames) {
2768 libs = systemNativeLibraries;
2769 if (libs == null) {
2770 libs = systemNativeLibraries = new ConcurrentHashMap<>();
2771 }
2772 }
2773 }
2774 return libs;
2775 }
2776
2777 /*
2778 * Returns the native libraries map associated with this class loader
2779 * This method will create the map at the first time when called.
2780 */
2781 private Map<String, NativeLibrary> nativeLibraries() {
2782 Map<String, NativeLibrary> libs = nativeLibraries;
2783 if (libs == null) {
2784 synchronized (loadedLibraryNames) {
2785 libs = nativeLibraries;
2786 if (libs == null) {
2787 libs = nativeLibraries = new ConcurrentHashMap<>();
2788 }
2789 }
2790 }
2791 return libs;
2792 }
2793
2794 // -- Assertion management --
2795
2796 final Object assertionLock;
2797
2798 // The default toggle for assertion checking.
2799 // @GuardedBy("assertionLock")
2800 private boolean defaultAssertionStatus = false;
2801
2802 // Maps String packageName to Boolean package default assertion status Note
2803 // that the default package is placed under a null map key. If this field
2804 // is null then we are delegating assertion status queries to the VM, i.e.,
2805 // none of this ClassLoader's assertion status modification methods have
2806 // been invoked.
2807 // @GuardedBy("assertionLock")
2808 private Map<String, Boolean> packageAssertionStatus = null;
2809
2810 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
2811 // field is null then we are delegating assertion status queries to the VM,
2812 // i.e., none of this ClassLoader's assertion status modification methods
2813 // have been invoked.
2814 // @GuardedBy("assertionLock")
2815 Map<String, Boolean> classAssertionStatus = null;
2816
2817 /**
2818 * Sets the default assertion status for this class loader. This setting
2819 * determines whether classes loaded by this class loader and initialized
2820 * in the future will have assertions enabled or disabled by default.
2821 * This setting may be overridden on a per-package or per-class basis by
2822 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
2823 * #setClassAssertionStatus(String, boolean)}.
2824 *
2825 * @param enabled
2826 * {@code true} if classes loaded by this class loader will
2827 * henceforth have assertions enabled by default, {@code false}
2828 * if they will have assertions disabled by default.
2829 *
2830 * @since 1.4
2831 */
2832 public void setDefaultAssertionStatus(boolean enabled) {
2833 synchronized (assertionLock) {
2834 if (classAssertionStatus == null)
2835 initializeJavaAssertionMaps();
2836
2837 defaultAssertionStatus = enabled;
2838 }
2839 }
2840
2841 /**
2842 * Sets the package default assertion status for the named package. The
2843 * package default assertion status determines the assertion status for
2844 * classes initialized in the future that belong to the named package or
2845 * any of its "subpackages".
2846 *
2847 * <p> A subpackage of a package named p is any package whose name begins
2848 * with "{@code p.}". For example, {@code javax.swing.text} is a
2849 * subpackage of {@code javax.swing}, and both {@code java.util} and
2850 * {@code java.lang.reflect} are subpackages of {@code java}.
2851 *
2852 * <p> In the event that multiple package defaults apply to a given class,
2853 * the package default pertaining to the most specific package takes
2854 * precedence over the others. For example, if {@code javax.lang} and
2855 * {@code javax.lang.reflect} both have package defaults associated with
2856 * them, the latter package default applies to classes in
2857 * {@code javax.lang.reflect}.
2858 *
2859 * <p> Package defaults take precedence over the class loader's default
2860 * assertion status, and may be overridden on a per-class basis by invoking
2861 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2862 *
2863 * @param packageName
2864 * The name of the package whose package default assertion status
2865 * is to be set. A {@code null} value indicates the unnamed
2866 * package that is "current"
2867 * (see section 7.4.2 of
2868 * <cite>The Java™ Language Specification</cite>.)
2869 *
2870 * @param enabled
2871 * {@code true} if classes loaded by this classloader and
2872 * belonging to the named package or any of its subpackages will
2873 * have assertions enabled by default, {@code false} if they will
2874 * have assertions disabled by default.
2875 *
2876 * @since 1.4
2877 */
2878 public void setPackageAssertionStatus(String packageName,
2879 boolean enabled) {
2880 synchronized (assertionLock) {
2881 if (packageAssertionStatus == null)
2882 initializeJavaAssertionMaps();
2883
2884 packageAssertionStatus.put(packageName, enabled);
2885 }
2886 }
2887
2888 /**
2889 * Sets the desired assertion status for the named top-level class in this
2890 * class loader and any nested classes contained therein. This setting
2891 * takes precedence over the class loader's default assertion status, and
2892 * over any applicable per-package default. This method has no effect if
2893 * the named class has already been initialized. (Once a class is
2894 * initialized, its assertion status cannot change.)
2895 *
2896 * <p> If the named class is not a top-level class, this invocation will
2897 * have no effect on the actual assertion status of any class. </p>
2898 *
2899 * @param className
2900 * The fully qualified class name of the top-level class whose
2901 * assertion status is to be set.
2902 *
2903 * @param enabled
2904 * {@code true} if the named class is to have assertions
2905 * enabled when (and if) it is initialized, {@code false} if the
2906 * class is to have assertions disabled.
2907 *
2908 * @since 1.4
2909 */
2910 public void setClassAssertionStatus(String className, boolean enabled) {
2911 synchronized (assertionLock) {
2912 if (classAssertionStatus == null)
2913 initializeJavaAssertionMaps();
2914
2915 classAssertionStatus.put(className, enabled);
2916 }
2917 }
2918
2919 /**
2920 * Sets the default assertion status for this class loader to
2921 * {@code false} and discards any package defaults or class assertion
2922 * status settings associated with the class loader. This method is
2923 * provided so that class loaders can be made to ignore any command line or
2924 * persistent assertion status settings and "start with a clean slate."
2925 *
2926 * @since 1.4
2927 */
2928 public void clearAssertionStatus() {
2929 /*
2930 * Whether or not "Java assertion maps" are initialized, set
2931 * them to empty maps, effectively ignoring any present settings.
2932 */
2933 synchronized (assertionLock) {
2934 classAssertionStatus = new HashMap<>();
2935 packageAssertionStatus = new HashMap<>();
2936 defaultAssertionStatus = false;
2937 }
2938 }
2939
2940 /**
2941 * Returns the assertion status that would be assigned to the specified
2942 * class if it were to be initialized at the time this method is invoked.
2943 * If the named class has had its assertion status set, the most recent
2944 * setting will be returned; otherwise, if any package default assertion
2945 * status pertains to this class, the most recent setting for the most
2946 * specific pertinent package default assertion status is returned;
2947 * otherwise, this class loader's default assertion status is returned.
2948 * </p>
2949 *
2950 * @param className
2951 * The fully qualified class name of the class whose desired
2952 * assertion status is being queried.
2953 *
2954 * @return The desired assertion status of the specified class.
2955 *
2956 * @see #setClassAssertionStatus(String, boolean)
2957 * @see #setPackageAssertionStatus(String, boolean)
2958 * @see #setDefaultAssertionStatus(boolean)
2959 *
2960 * @since 1.4
2961 */
2962 boolean desiredAssertionStatus(String className) {
2963 synchronized (assertionLock) {
2964 // assert classAssertionStatus != null;
2965 // assert packageAssertionStatus != null;
2966
2967 // Check for a class entry
2968 Boolean result = classAssertionStatus.get(className);
2969 if (result != null)
2970 return result.booleanValue();
2971
2972 // Check for most specific package entry
2973 int dotIndex = className.lastIndexOf('.');
2974 if (dotIndex < 0) { // default package
2975 result = packageAssertionStatus.get(null);
2976 if (result != null)
2977 return result.booleanValue();
2978 }
2979 while(dotIndex > 0) {
2980 className = className.substring(0, dotIndex);
2981 result = packageAssertionStatus.get(className);
2982 if (result != null)
2983 return result.booleanValue();
2984 dotIndex = className.lastIndexOf('.', dotIndex-1);
2985 }
2986
2987 // Return the classloader default
2988 return defaultAssertionStatus;
2989 }
2990 }
2991
2992 // Set up the assertions with information provided by the VM.
2993 // Note: Should only be called inside a synchronized block
2994 private void initializeJavaAssertionMaps() {
2995 // assert Thread.holdsLock(assertionLock);
2996
2997 classAssertionStatus = new HashMap<>();
2998 packageAssertionStatus = new HashMap<>();
2999 AssertionStatusDirectives directives = retrieveDirectives();
3000
3001 for(int i = 0; i < directives.classes.length; i++)
3002 classAssertionStatus.put(directives.classes[i],
3003 directives.classEnabled[i]);
3004
3005 for(int i = 0; i < directives.packages.length; i++)
3006 packageAssertionStatus.put(directives.packages[i],
3007 directives.packageEnabled[i]);
3008
3009 defaultAssertionStatus = directives.deflt;
3010 }
3011
3012 // Retrieves the assertion directives from the VM.
3013 private static native AssertionStatusDirectives retrieveDirectives();
3014
3015
3016 // -- Misc --
3017
3018 /**
3019 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
3020 * associated with this ClassLoader, creating it if it doesn't already exist.
3021 */
3022 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
3023 ConcurrentHashMap<?, ?> map = classLoaderValueMap;
3024 if (map == null) {
3025 map = new ConcurrentHashMap<>();
3026 boolean set = trySetObjectField("classLoaderValueMap", map);
3027 if (!set) {
3028 // beaten by someone else
3029 map = classLoaderValueMap;
3030 }
3031 }
3032 return map;
3033 }
3034
3035 // the storage for ClassLoaderValue(s) associated with this ClassLoader
3036 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
3037
3038 /**
3039 * Attempts to atomically set a volatile field in this object. Returns
3040 * {@code true} if not beaten by another thread. Avoids the use of
3041 * AtomicReferenceFieldUpdater in this class.
3042 */
3043 private boolean trySetObjectField(String name, Object obj) {
3044 Unsafe unsafe = Unsafe.getUnsafe();
3045 Class<?> k = ClassLoader.class;
3046 long offset;
3047 offset = unsafe.objectFieldOffset(k, name);
3048 return unsafe.compareAndSetReference(this, offset, null, obj);
3049 }
3050 }
3051
3052 /*
3053 * A utility class that will enumerate over an array of enumerations.
3054 */
3055 final class CompoundEnumeration<E> implements Enumeration<E> {
3056 private final Enumeration<E>[] enums;
3057 private int index;
3058
3059 public CompoundEnumeration(Enumeration<E>[] enums) {
3060 this.enums = enums;
3061 }
3062
3063 private boolean next() {
3064 while (index < enums.length) {
3065 if (enums[index] != null && enums[index].hasMoreElements()) {
3066 return true;
3067 }
3068 index++;
3069 }
3070 return false;
3071 }
3072
3073 public boolean hasMoreElements() {
3074 return next();
3075 }
3076
3077 public E nextElement() {
3078 if (!next()) {
3079 throw new NoSuchElementException();
3080 }
3081 return enums[index].nextElement();
3082 }
3083 }