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