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