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