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