1 /*
2 * Copyright (c) 2013, 2015 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 package java.lang;
26
27 import java.io.InputStream;
28 import java.io.IOException;
29 import java.io.File;
30 import java.lang.reflect.Constructor;
31 import java.lang.reflect.InvocationTargetException;
32 import java.net.URL;
33 import java.security.AccessController;
34 import java.security.AccessControlContext;
35 import java.security.CodeSource;
36 import java.security.PrivilegedAction;
37 import java.security.PrivilegedActionException;
38 import java.security.PrivilegedExceptionAction;
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.Set;
46 import java.util.Stack;
47 import java.util.Map;
48 import java.util.NoSuchElementException;
49 import java.util.Vector;
50 import java.util.Hashtable;
51 import java.util.WeakHashMap;
52 import java.util.concurrent.ConcurrentHashMap;
53
54 import jdk.internal.perf.PerfCounter;
55 import sun.misc.Resource;
56 import sun.misc.URLClassPath;
57 import sun.reflect.CallerSensitive;
58 import sun.reflect.Reflection;
59 import sun.reflect.misc.ReflectUtil;
60 import sun.security.util.SecurityConstants;
61
62 /**
63 * A class loader is an object that is responsible for loading classes. The
64 * class <tt>ClassLoader</tt> is an abstract class. Given the <a
65 * href="#name">binary name</a> of a class, a class loader should attempt to
66 * locate or generate data that constitutes a definition for the class. A
67 * typical strategy is to transform the name into a file name and then read a
68 * "class file" of that name from a file system.
69 *
70 * <p> Every {@link Class <tt>Class</tt>} object contains a {@link
71 * Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
72 * it.
73 *
74 * <p> <tt>Class</tt> objects for array classes are not created by class
75 * loaders, but are created automatically as required by the Java runtime.
76 * The class loader for an array class, as returned by {@link
77 * Class#getClassLoader()} is the same as the class loader for its element
78 * type; if the element type is a primitive type, then the array class has no
79 * class loader.
80 *
81 * <p> Applications implement subclasses of <tt>ClassLoader</tt> in order to
82 * extend the manner in which the Java virtual machine dynamically loads
83 * classes.
84 *
85 * <p> Class loaders may typically be used by security managers to indicate
86 * security domains.
87 *
88 * <p> The <tt>ClassLoader</tt> class uses a delegation model to search for
89 * classes and resources. Each instance of <tt>ClassLoader</tt> has an
90 * associated parent class loader. When requested to find a class or
91 * resource, a <tt>ClassLoader</tt> instance will delegate the search for the
92 * class or resource to its parent class loader before attempting to find the
93 * class or resource itself. The virtual machine's built-in class loader,
94 * called the "bootstrap class loader", does not itself have a parent but may
95 * serve as the parent of a <tt>ClassLoader</tt> instance.
96 *
97 * <p> Class loaders that support concurrent loading of classes are known as
98 * <em>parallel capable</em> class loaders and are required to register
99 * themselves at their class initialization time by invoking the
100 * {@link
101 * #registerAsParallelCapable <tt>ClassLoader.registerAsParallelCapable</tt>}
102 * method. Note that the <tt>ClassLoader</tt> class is registered as parallel
103 * capable by default. However, its subclasses still need to register themselves
104 * if they are parallel capable. <br>
105 * In environments in which the delegation model is not strictly
106 * hierarchical, class loaders need to be parallel capable, otherwise class
107 * loading can lead to deadlocks because the loader lock is held for the
108 * duration of the class loading process (see {@link #loadClass
109 * <tt>loadClass</tt>} methods).
110 *
111 * <p> Normally, the Java virtual machine loads classes from the local file
112 * system in a platform-dependent manner. For example, on UNIX systems, the
113 * virtual machine loads classes from the directory defined by the
114 * <tt>CLASSPATH</tt> environment variable.
115 *
116 * <p> However, some classes may not originate from a file; they may originate
117 * from other sources, such as the network, or they could be constructed by an
118 * application. The method {@link #defineClass(String, byte[], int, int)
119 * <tt>defineClass</tt>} converts an array of bytes into an instance of class
120 * <tt>Class</tt>. Instances of this newly defined class can be created using
121 * {@link Class#newInstance <tt>Class.newInstance</tt>}.
122 *
123 * <p> The methods and constructors of objects created by a class loader may
124 * reference other classes. To determine the class(es) referred to, the Java
125 * virtual machine invokes the {@link #loadClass <tt>loadClass</tt>} method of
126 * the class loader that originally created the class.
127 *
128 * <p> For example, an application could create a network class loader to
129 * download class files from a server. Sample code might look like:
130 *
131 * <blockquote><pre>
132 * ClassLoader loader = new NetworkClassLoader(host, port);
133 * Object main = loader.loadClass("Main", true).newInstance();
134 * . . .
135 * </pre></blockquote>
136 *
137 * <p> The network class loader subclass must define the methods {@link
138 * #findClass <tt>findClass</tt>} and <tt>loadClassData</tt> to load a class
139 * from the network. Once it has downloaded the bytes that make up the class,
140 * it should use the method {@link #defineClass <tt>defineClass</tt>} to
141 * create a class instance. A sample implementation is:
142 *
143 * <blockquote><pre>
144 * class NetworkClassLoader extends ClassLoader {
145 * String host;
146 * int port;
147 *
148 * public Class findClass(String name) {
149 * byte[] b = loadClassData(name);
150 * return defineClass(name, b, 0, b.length);
151 * }
152 *
153 * private byte[] loadClassData(String name) {
154 * // load the class data from the connection
155 * . . .
156 * }
157 * }
158 * </pre></blockquote>
159 *
160 * <h3> <a name="name">Binary names</a> </h3>
161 *
162 * <p> Any class name provided as a {@link String} parameter to methods in
163 * <tt>ClassLoader</tt> must be a binary name as defined by
164 * <cite>The Java™ Language Specification</cite>.
165 *
166 * <p> Examples of valid class names include:
167 * <blockquote><pre>
168 * "java.lang.String"
169 * "javax.swing.JSpinner$DefaultEditor"
170 * "java.security.KeyStore$Builder$FileBuilder$1"
171 * "java.net.URLClassLoader$3$1"
172 * </pre></blockquote>
173 *
174 * {@code Class} objects for array classes are not created by {@code ClassLoader};
175 * use the {@link Class#forName} method instead.
176 *
177 * @jls 13.1 The Form of a Binary
178 * @see #resolveClass(Class)
179 * @since 1.0
180 */
181 public abstract class ClassLoader {
182
183 private static native void registerNatives();
184 static {
185 registerNatives();
186 }
187
188 // The parent class loader for delegation
189 // Note: VM hardcoded the offset of this field, thus all new fields
190 // must be added *after* it.
191 private final ClassLoader parent;
192
193 /**
194 * Encapsulates the set of parallel capable loader types.
195 */
196 private static class ParallelLoaders {
197 private ParallelLoaders() {}
198
199 // the set of parallel capable loader types
200 private static final Set<Class<? extends ClassLoader>> loaderTypes =
201 Collections.newSetFromMap(new WeakHashMap<>());
202 static {
203 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
204 }
205
206 /**
207 * Registers the given class loader type as parallel capable.
208 * Returns {@code true} is successfully registered; {@code false} if
209 * loader's super class is not registered.
210 */
211 static boolean register(Class<? extends ClassLoader> c) {
212 synchronized (loaderTypes) {
213 if (loaderTypes.contains(c.getSuperclass())) {
214 // register the class loader as parallel capable
215 // if and only if all of its super classes are.
216 // Note: given current classloading sequence, if
217 // the immediate super class is parallel capable,
218 // all the super classes higher up must be too.
219 loaderTypes.add(c);
220 return true;
221 } else {
222 return false;
223 }
224 }
225 }
226
227 /**
228 * Returns {@code true} if the given class loader type is
229 * registered as parallel capable.
230 */
231 static boolean isRegistered(Class<? extends ClassLoader> c) {
232 synchronized (loaderTypes) {
233 return loaderTypes.contains(c);
234 }
235 }
236 }
237
238 // Maps class name to the corresponding lock object when the current
239 // class loader is parallel capable.
240 // Note: VM also uses this field to decide if the current class loader
241 // is parallel capable and the appropriate lock object for class loading.
242 private final ConcurrentHashMap<String, Object> parallelLockMap;
243
244 // Hashtable that maps packages to certs
245 private final Map <String, Certificate[]> package2certs;
246
247 // Shared among all packages with unsigned classes
248 private static final Certificate[] nocerts = new Certificate[0];
249
250 // The classes loaded by this class loader. The only purpose of this table
251 // is to keep the classes from being GC'ed until the loader is GC'ed.
252 private final Vector<Class<?>> classes = new Vector<>();
253
254 // The "default" domain. Set as the default ProtectionDomain on newly
255 // created classes.
256 private final ProtectionDomain defaultDomain =
257 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
258 null, this, null);
259
260 // The initiating protection domains for all classes loaded by this loader
261 private final Set<ProtectionDomain> domains;
262
263 // Invoked by the VM to record every loaded class with this loader.
264 void addClass(Class<?> c) {
265 classes.addElement(c);
266 }
267
268 // The packages defined in this class loader. Each package name is mapped
269 // to its corresponding Package object.
270 private final ConcurrentHashMap<String, Package> packages
271 = new ConcurrentHashMap<>();
272
273 private static Void checkCreateClassLoader() {
274 SecurityManager security = System.getSecurityManager();
275 if (security != null) {
276 security.checkCreateClassLoader();
277 }
278 return null;
279 }
280
281 private ClassLoader(Void unused, ClassLoader parent) {
282 this.parent = parent;
283 if (ParallelLoaders.isRegistered(this.getClass())) {
284 parallelLockMap = new ConcurrentHashMap<>();
285 package2certs = new ConcurrentHashMap<>();
286 domains = Collections.synchronizedSet(new HashSet<>());
287 assertionLock = new Object();
288 } else {
289 // no finer-grained lock; lock on the classloader instance
290 parallelLockMap = null;
291 package2certs = new Hashtable<>();
292 domains = new HashSet<>();
293 assertionLock = this;
294 }
295 }
296
297 /**
298 * Creates a new class loader using the specified parent class loader for
299 * delegation.
300 *
301 * <p> If there is a security manager, its {@link
302 * SecurityManager#checkCreateClassLoader()
303 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
304 * a security exception. </p>
305 *
306 * @param parent
307 * The parent class loader
308 *
309 * @throws SecurityException
310 * If a security manager exists and its
311 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
312 * of a new class loader.
313 *
314 * @since 1.2
315 */
316 protected ClassLoader(ClassLoader parent) {
317 this(checkCreateClassLoader(), parent);
318 }
319
320 /**
321 * Creates a new class loader using the <tt>ClassLoader</tt> returned by
322 * the method {@link #getSystemClassLoader()
323 * <tt>getSystemClassLoader()</tt>} as the parent class loader.
324 *
325 * <p> If there is a security manager, its {@link
326 * SecurityManager#checkCreateClassLoader()
327 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
328 * a security exception. </p>
329 *
330 * @throws SecurityException
331 * If a security manager exists and its
332 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
333 * of a new class loader.
334 */
335 protected ClassLoader() {
336 this(checkCreateClassLoader(), getSystemClassLoader());
337 }
338
339 // -- Class --
340
341 /**
342 * Loads the class with the specified <a href="#name">binary name</a>.
343 * This method searches for classes in the same manner as the {@link
344 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
345 * machine to resolve class references. Invoking this method is equivalent
346 * to invoking {@link #loadClass(String, boolean) <tt>loadClass(name,
347 * false)</tt>}.
348 *
349 * @param name
350 * The <a href="#name">binary name</a> of the class
351 *
352 * @return The resulting <tt>Class</tt> object
353 *
354 * @throws ClassNotFoundException
355 * If the class was not found
356 */
357 public Class<?> loadClass(String name) throws ClassNotFoundException {
358 return loadClass(name, false);
359 }
360
361 /**
362 * Loads the class with the specified <a href="#name">binary name</a>. The
363 * default implementation of this method searches for classes in the
364 * following order:
365 *
366 * <ol>
367 *
368 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
369 * has already been loaded. </p></li>
370 *
371 * <li><p> Invoke the {@link #loadClass(String) <tt>loadClass</tt>} method
372 * on the parent class loader. If the parent is <tt>null</tt> the class
373 * loader built-in to the virtual machine is used, instead. </p></li>
374 *
375 * <li><p> Invoke the {@link #findClass(String)} method to find the
376 * class. </p></li>
377 *
378 * </ol>
379 *
380 * <p> If the class was found using the above steps, and the
381 * <tt>resolve</tt> flag is true, this method will then invoke the {@link
382 * #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
383 *
384 * <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
385 * #findClass(String)}, rather than this method. </p>
386 *
387 * <p> Unless overridden, this method synchronizes on the result of
388 * {@link #getClassLoadingLock <tt>getClassLoadingLock</tt>} method
389 * during the entire class loading process.
390 *
391 * @param name
392 * The <a href="#name">binary name</a> of the class
393 *
394 * @param resolve
395 * If <tt>true</tt> then resolve the class
396 *
397 * @return The resulting <tt>Class</tt> object
398 *
399 * @throws ClassNotFoundException
400 * If the class could not be found
401 */
402 protected Class<?> loadClass(String name, boolean resolve)
403 throws ClassNotFoundException
404 {
405 synchronized (getClassLoadingLock(name)) {
406 // First, check if the class has already been loaded
407 Class<?> c = findLoadedClass(name);
408 if (c == null) {
409 long t0 = System.nanoTime();
410 try {
411 if (parent != null) {
412 c = parent.loadClass(name, false);
413 } else {
414 c = findBootstrapClassOrNull(name);
415 }
416 } catch (ClassNotFoundException e) {
417 // ClassNotFoundException thrown if class not found
418 // from the non-null parent class loader
419 }
420
421 if (c == null) {
422 // If still not found, then invoke findClass in order
423 // to find the class.
424 long t1 = System.nanoTime();
425 c = findClass(name);
426
427 // this is the defining class loader; record the stats
428 PerfCounter.getParentDelegationTime().addTime(t1 - t0);
429 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
430 PerfCounter.getFindClasses().increment();
431 }
432 }
433 if (resolve) {
434 resolveClass(c);
435 }
436 return c;
437 }
438 }
439
440 /**
441 * Returns the lock object for class loading operations.
442 * For backward compatibility, the default implementation of this method
443 * behaves as follows. If this ClassLoader object is registered as
444 * parallel capable, the method returns a dedicated object associated
445 * with the specified class name. Otherwise, the method returns this
446 * ClassLoader object.
447 *
448 * @param className
449 * The name of the to-be-loaded class
450 *
451 * @return the lock for class loading operations
452 *
453 * @throws NullPointerException
454 * If registered as parallel capable and <tt>className</tt> is null
455 *
456 * @see #loadClass(String, boolean)
457 *
458 * @since 1.7
459 */
460 protected Object getClassLoadingLock(String className) {
461 Object lock = this;
462 if (parallelLockMap != null) {
463 Object newLock = new Object();
464 lock = parallelLockMap.putIfAbsent(className, newLock);
465 if (lock == null) {
466 lock = newLock;
467 }
468 }
469 return lock;
470 }
471
472 // This method is invoked by the virtual machine to load a class.
473 private Class<?> loadClassInternal(String name)
474 throws ClassNotFoundException
475 {
476 // For backward compatibility, explicitly lock on 'this' when
477 // the current class loader is not parallel capable.
478 if (parallelLockMap == null) {
479 synchronized (this) {
480 return loadClass(name);
481 }
482 } else {
483 return loadClass(name);
484 }
485 }
486
487 // Invoked by the VM after loading class with this loader.
488 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
489 final SecurityManager sm = System.getSecurityManager();
490 if (sm != null) {
491 if (ReflectUtil.isNonPublicProxyClass(cls)) {
492 for (Class<?> intf: cls.getInterfaces()) {
493 checkPackageAccess(intf, pd);
494 }
495 return;
496 }
497
498 final String name = cls.getName();
499 final int i = name.lastIndexOf('.');
500 if (i != -1) {
501 AccessController.doPrivileged(new PrivilegedAction<>() {
502 public Void run() {
503 sm.checkPackageAccess(name.substring(0, i));
504 return null;
505 }
506 }, new AccessControlContext(new ProtectionDomain[] {pd}));
507 }
508 }
509 domains.add(pd);
510 }
511
512 /**
513 * Finds the class with the specified <a href="#name">binary name</a>.
514 * This method should be overridden by class loader implementations that
515 * follow the delegation model for loading classes, and will be invoked by
516 * the {@link #loadClass <tt>loadClass</tt>} method after checking the
517 * parent class loader for the requested class. The default implementation
518 * throws a <tt>ClassNotFoundException</tt>.
519 *
520 * @param name
521 * The <a href="#name">binary name</a> of the class
522 *
523 * @return The resulting <tt>Class</tt> object
524 *
525 * @throws ClassNotFoundException
526 * If the class could not be found
527 *
528 * @since 1.2
529 */
530 protected Class<?> findClass(String name) throws ClassNotFoundException {
531 throw new ClassNotFoundException(name);
532 }
533
534 /**
535 * Converts an array of bytes into an instance of class <tt>Class</tt>.
536 * Before the <tt>Class</tt> can be used it must be resolved. This method
537 * is deprecated in favor of the version that takes a <a
538 * href="#name">binary name</a> as its first argument, and is more secure.
539 *
540 * @param b
541 * The bytes that make up the class data. The bytes in positions
542 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
543 * of a valid class file as defined by
544 * <cite>The Java™ Virtual Machine Specification</cite>.
545 *
546 * @param off
547 * The start offset in <tt>b</tt> of the class data
548 *
549 * @param len
550 * The length of the class data
551 *
552 * @return The <tt>Class</tt> object that was created from the specified
553 * class data
554 *
555 * @throws ClassFormatError
556 * If the data did not contain a valid class
557 *
558 * @throws IndexOutOfBoundsException
559 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
560 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
561 *
562 * @throws SecurityException
563 * If an attempt is made to add this class to a package that
564 * contains classes that were signed by a different set of
565 * certificates than this class, or if an attempt is made
566 * to define a class in a package with a fully-qualified name
567 * that starts with "{@code java.}".
568 *
569 * @see #loadClass(String, boolean)
570 * @see #resolveClass(Class)
571 *
572 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
573 * defineClass(String, byte[], int, int)}
574 */
575 @Deprecated
576 protected final Class<?> defineClass(byte[] b, int off, int len)
577 throws ClassFormatError
578 {
579 return defineClass(null, b, off, len, null);
580 }
581
582 /**
583 * Converts an array of bytes into an instance of class <tt>Class</tt>.
584 * Before the <tt>Class</tt> can be used it must be resolved.
585 *
586 * <p> This method assigns a default {@link java.security.ProtectionDomain
587 * <tt>ProtectionDomain</tt>} to the newly defined class. The
588 * <tt>ProtectionDomain</tt> is effectively granted the same set of
589 * permissions returned when {@link
590 * java.security.Policy#getPermissions(java.security.CodeSource)
591 * <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
592 * is invoked. The default domain is created on the first invocation of
593 * {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
594 * and re-used on subsequent invocations.
595 *
596 * <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
597 * the {@link #defineClass(String, byte[], int, int,
598 * java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
599 * <tt>ProtectionDomain</tt> as one of its arguments. </p>
600 *
601 * @param name
602 * The expected <a href="#name">binary name</a> of the class, or
603 * <tt>null</tt> if not known
604 *
605 * @param b
606 * The bytes that make up the class data. The bytes in positions
607 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
608 * of a valid class file as defined by
609 * <cite>The Java™ Virtual Machine Specification</cite>.
610 *
611 * @param off
612 * The start offset in <tt>b</tt> of the class data
613 *
614 * @param len
615 * The length of the class data
616 *
617 * @return The <tt>Class</tt> object that was created from the specified
618 * class data.
619 *
620 * @throws ClassFormatError
621 * If the data did not contain a valid class
622 *
623 * @throws IndexOutOfBoundsException
624 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
625 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
626 *
627 * @throws SecurityException
628 * If an attempt is made to add this class to a package that
629 * contains classes that were signed by a different set of
630 * certificates than this class (which is unsigned), or if
631 * <tt>name</tt> begins with "<tt>java.</tt>".
632 *
633 * @see #loadClass(String, boolean)
634 * @see #resolveClass(Class)
635 * @see java.security.CodeSource
636 * @see java.security.SecureClassLoader
637 *
638 * @since 1.1
639 */
640 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
641 throws ClassFormatError
642 {
643 return defineClass(name, b, off, len, null);
644 }
645
646 /* Determine protection domain, and check that:
647 - not define java.* class,
648 - signer of this class matches signers for the rest of the classes in
649 package.
650 */
651 private ProtectionDomain preDefineClass(String name,
652 ProtectionDomain pd)
653 {
654 if (!checkName(name))
655 throw new NoClassDefFoundError("IllegalName: " + name);
656
657 if ((name != null) && name.startsWith("java.")) {
658 throw new SecurityException
659 ("Prohibited package name: " +
660 name.substring(0, name.lastIndexOf('.')));
661 }
662 if (pd == null) {
663 pd = defaultDomain;
664 }
665
666 if (name != null) checkCerts(name, pd.getCodeSource());
667
668 return pd;
669 }
670
671 private String defineClassSourceLocation(ProtectionDomain pd)
672 {
673 CodeSource cs = pd.getCodeSource();
674 String source = null;
675 if (cs != null && cs.getLocation() != null) {
676 source = cs.getLocation().toString();
677 }
678 return source;
679 }
680
681 private void postDefineClass(Class<?> c, ProtectionDomain pd)
682 {
683 if (pd.getCodeSource() != null) {
684 Certificate certs[] = pd.getCodeSource().getCertificates();
685 if (certs != null)
686 setSigners(c, certs);
687 }
688 }
689
690 /**
691 * Converts an array of bytes into an instance of class <tt>Class</tt>,
692 * with an optional <tt>ProtectionDomain</tt>. If the domain is
693 * <tt>null</tt>, then a default domain will be assigned to the class as
694 * specified in the documentation for {@link #defineClass(String, byte[],
695 * int, int)}. Before the class can be used it must be resolved.
696 *
697 * <p> The first class defined in a package determines the exact set of
698 * certificates that all subsequent classes defined in that package must
699 * contain. The set of certificates for a class is obtained from the
700 * {@link java.security.CodeSource <tt>CodeSource</tt>} within the
701 * <tt>ProtectionDomain</tt> of the class. Any classes added to that
702 * package must contain the same set of certificates or a
703 * <tt>SecurityException</tt> will be thrown. Note that if
704 * <tt>name</tt> is <tt>null</tt>, this check is not performed.
705 * You should always pass in the <a href="#name">binary name</a> of the
706 * class you are defining as well as the bytes. This ensures that the
707 * class you are defining is indeed the class you think it is.
708 *
709 * <p> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
710 * all classes in the "<tt>java.*</tt> packages can only be defined by the
711 * bootstrap class loader. If <tt>name</tt> is not <tt>null</tt>, it
712 * must be equal to the <a href="#name">binary name</a> of the class
713 * specified by the byte array "<tt>b</tt>", otherwise a {@link
714 * NoClassDefFoundError <tt>NoClassDefFoundError</tt>} will be thrown. </p>
715 *
716 * @param name
717 * The expected <a href="#name">binary name</a> of the class, or
718 * <tt>null</tt> if not known
719 *
720 * @param b
721 * The bytes that make up the class data. The bytes in positions
722 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
723 * of a valid class file as defined by
724 * <cite>The Java™ Virtual Machine Specification</cite>.
725 *
726 * @param off
727 * The start offset in <tt>b</tt> of the class data
728 *
729 * @param len
730 * The length of the class data
731 *
732 * @param protectionDomain
733 * The ProtectionDomain of the class
734 *
735 * @return The <tt>Class</tt> object created from the data,
736 * and optional <tt>ProtectionDomain</tt>.
737 *
738 * @throws ClassFormatError
739 * If the data did not contain a valid class
740 *
741 * @throws NoClassDefFoundError
742 * If <tt>name</tt> is not equal to the <a href="#name">binary
743 * name</a> of the class specified by <tt>b</tt>
744 *
745 * @throws IndexOutOfBoundsException
746 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
747 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
748 *
749 * @throws SecurityException
750 * If an attempt is made to add this class to a package that
751 * contains classes that were signed by a different set of
752 * certificates than this class, or if <tt>name</tt> begins with
753 * "<tt>java.</tt>".
754 */
755 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
756 ProtectionDomain protectionDomain)
757 throws ClassFormatError
758 {
759 protectionDomain = preDefineClass(name, protectionDomain);
760 String source = defineClassSourceLocation(protectionDomain);
761 Class<?> c = defineClass1(name, b, off, len, protectionDomain, source);
762 postDefineClass(c, protectionDomain);
763 return c;
764 }
765
766 /**
767 * Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
768 * into an instance of class <tt>Class</tt>,
769 * with an optional <tt>ProtectionDomain</tt>. If the domain is
770 * <tt>null</tt>, then a default domain will be assigned to the class as
771 * specified in the documentation for {@link #defineClass(String, byte[],
772 * int, int)}. Before the class can be used it must be resolved.
773 *
774 * <p>The rules about the first class defined in a package determining the
775 * set of certificates for the package, and the restrictions on class names
776 * are identical to those specified in the documentation for {@link
777 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
778 *
779 * <p> An invocation of this method of the form
780 * <i>cl</i><tt>.defineClass(</tt><i>name</i><tt>,</tt>
781 * <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
782 * result as the statements
783 *
784 *<p> <tt>
785 * ...<br>
786 * byte[] temp = new byte[bBuffer.{@link
787 * java.nio.ByteBuffer#remaining remaining}()];<br>
788 * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
789 * get}(temp);<br>
790 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
791 * cl.defineClass}(name, temp, 0,
792 * temp.length, pd);<br>
793 * </tt></p>
794 *
795 * @param name
796 * The expected <a href="#name">binary name</a>. of the class, or
797 * <tt>null</tt> if not known
798 *
799 * @param b
800 * The bytes that make up the class data. The bytes from positions
801 * <tt>b.position()</tt> through <tt>b.position() + b.limit() -1
802 * </tt> should have the format of a valid class file as defined by
803 * <cite>The Java™ Virtual Machine Specification</cite>.
804 *
805 * @param protectionDomain
806 * The ProtectionDomain of the class, or <tt>null</tt>.
807 *
808 * @return The <tt>Class</tt> object created from the data,
809 * and optional <tt>ProtectionDomain</tt>.
810 *
811 * @throws ClassFormatError
812 * If the data did not contain a valid class.
813 *
814 * @throws NoClassDefFoundError
815 * If <tt>name</tt> is not equal to the <a href="#name">binary
816 * name</a> of the class specified by <tt>b</tt>
817 *
818 * @throws SecurityException
819 * If an attempt is made to add this class to a package that
820 * contains classes that were signed by a different set of
821 * certificates than this class, or if <tt>name</tt> begins with
822 * "<tt>java.</tt>".
823 *
824 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
825 *
826 * @since 1.5
827 */
828 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
829 ProtectionDomain protectionDomain)
830 throws ClassFormatError
831 {
832 int len = b.remaining();
833
834 // Use byte[] if not a direct ByteBuffer:
835 if (!b.isDirect()) {
836 if (b.hasArray()) {
837 return defineClass(name, b.array(),
838 b.position() + b.arrayOffset(), len,
839 protectionDomain);
840 } else {
841 // no array, or read-only array
842 byte[] tb = new byte[len];
843 b.get(tb); // get bytes out of byte buffer.
844 return defineClass(name, tb, 0, len, protectionDomain);
845 }
846 }
847
848 protectionDomain = preDefineClass(name, protectionDomain);
849 String source = defineClassSourceLocation(protectionDomain);
850 Class<?> c = defineClass2(name, b, b.position(), len, protectionDomain, source);
851 postDefineClass(c, protectionDomain);
852 return c;
853 }
854
855 private native Class<?> defineClass1(String name, byte[] b, int off, int len,
856 ProtectionDomain pd, String source);
857
858 private native Class<?> defineClass2(String name, java.nio.ByteBuffer b,
859 int off, int len, ProtectionDomain pd,
860 String source);
861
862 // true if the name is null or has the potential to be a valid binary name
863 private boolean checkName(String name) {
864 if ((name == null) || (name.length() == 0))
865 return true;
866 if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
867 return false;
868 return true;
869 }
870
871 private void checkCerts(String name, CodeSource cs) {
872 int i = name.lastIndexOf('.');
873 String pname = (i == -1) ? "" : name.substring(0, i);
874
875 Certificate[] certs = null;
876 if (cs != null) {
877 certs = cs.getCertificates();
878 }
879 Certificate[] pcerts = null;
880 if (parallelLockMap == null) {
881 synchronized (this) {
882 pcerts = package2certs.get(pname);
883 if (pcerts == null) {
884 package2certs.put(pname, (certs == null? nocerts:certs));
885 }
886 }
887 } else {
888 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
889 putIfAbsent(pname, (certs == null? nocerts:certs));
890 }
891 if (pcerts != null && !compareCerts(pcerts, certs)) {
892 throw new SecurityException("class \""+ name +
893 "\"'s signer information does not match signer information of other classes in the same package");
894 }
895 }
896
897 /**
898 * check to make sure the certs for the new class (certs) are the same as
899 * the certs for the first class inserted in the package (pcerts)
900 */
901 private boolean compareCerts(Certificate[] pcerts,
902 Certificate[] certs)
903 {
904 // certs can be null, indicating no certs.
905 if ((certs == null) || (certs.length == 0)) {
906 return pcerts.length == 0;
907 }
908
909 // the length must be the same at this point
910 if (certs.length != pcerts.length)
911 return false;
912
913 // go through and make sure all the certs in one array
914 // are in the other and vice-versa.
915 boolean match;
916 for (Certificate cert : certs) {
917 match = false;
918 for (Certificate pcert : pcerts) {
919 if (cert.equals(pcert)) {
920 match = true;
921 break;
922 }
923 }
924 if (!match) return false;
925 }
926
927 // now do the same for pcerts
928 for (Certificate pcert : pcerts) {
929 match = false;
930 for (Certificate cert : certs) {
931 if (pcert.equals(cert)) {
932 match = true;
933 break;
934 }
935 }
936 if (!match) return false;
937 }
938
939 return true;
940 }
941
942 /**
943 * Links the specified class. This (misleadingly named) method may be
944 * used by a class loader to link a class. If the class <tt>c</tt> has
945 * already been linked, then this method simply returns. Otherwise, the
946 * class is linked as described in the "Execution" chapter of
947 * <cite>The Java™ Language Specification</cite>.
948 *
949 * @param c
950 * The class to link
951 *
952 * @throws NullPointerException
953 * If <tt>c</tt> is <tt>null</tt>.
954 *
955 * @see #defineClass(String, byte[], int, int)
956 */
957 protected final void resolveClass(Class<?> c) {
958 if (c == null) {
959 throw new NullPointerException();
960 }
961 }
962
963 /**
964 * Finds a class with the specified <a href="#name">binary name</a>,
965 * loading it if necessary.
966 *
967 * <p> This method loads the class through the system class loader (see
968 * {@link #getSystemClassLoader()}). The <tt>Class</tt> object returned
969 * might have more than one <tt>ClassLoader</tt> associated with it.
970 * Subclasses of <tt>ClassLoader</tt> need not usually invoke this method,
971 * because most class loaders need to override just {@link
972 * #findClass(String)}. </p>
973 *
974 * @param name
975 * The <a href="#name">binary name</a> of the class
976 *
977 * @return The <tt>Class</tt> object for the specified <tt>name</tt>
978 *
979 * @throws ClassNotFoundException
980 * If the class could not be found
981 *
982 * @see #ClassLoader(ClassLoader)
983 * @see #getParent()
984 */
985 protected final Class<?> findSystemClass(String name)
986 throws ClassNotFoundException
987 {
988 ClassLoader system = getSystemClassLoader();
989 if (system == null) {
990 if (!checkName(name))
991 throw new ClassNotFoundException(name);
992 Class<?> cls = findBootstrapClass(name);
993 if (cls == null) {
994 throw new ClassNotFoundException(name);
995 }
996 return cls;
997 }
998 return system.loadClass(name);
999 }
1000
1001 /**
1002 * Returns a class loaded by the bootstrap class loader;
1003 * or return null if not found.
1004 */
1005 private Class<?> findBootstrapClassOrNull(String name)
1006 {
1007 if (!checkName(name)) return null;
1008
1009 return findBootstrapClass(name);
1010 }
1011
1012 // return null if not found
1013 private native Class<?> findBootstrapClass(String name);
1014
1015 /**
1016 * Returns the class with the given <a href="#name">binary name</a> if this
1017 * loader has been recorded by the Java virtual machine as an initiating
1018 * loader of a class with that <a href="#name">binary name</a>. Otherwise
1019 * <tt>null</tt> is returned.
1020 *
1021 * @param name
1022 * The <a href="#name">binary name</a> of the class
1023 *
1024 * @return The <tt>Class</tt> object, or <tt>null</tt> if the class has
1025 * not been loaded
1026 *
1027 * @since 1.1
1028 */
1029 protected final Class<?> findLoadedClass(String name) {
1030 if (!checkName(name))
1031 return null;
1032 return findLoadedClass0(name);
1033 }
1034
1035 private final native Class<?> findLoadedClass0(String name);
1036
1037 /**
1038 * Sets the signers of a class. This should be invoked after defining a
1039 * class.
1040 *
1041 * @param c
1042 * The <tt>Class</tt> object
1043 *
1044 * @param signers
1045 * The signers for the class
1046 *
1047 * @since 1.1
1048 */
1049 protected final void setSigners(Class<?> c, Object[] signers) {
1050 c.setSigners(signers);
1051 }
1052
1053
1054 // -- Resource --
1055
1056 /**
1057 * Finds the resource with the given name. A resource is some data
1058 * (images, audio, text, etc) that can be accessed by class code in a way
1059 * that is independent of the location of the code.
1060 *
1061 * <p> The name of a resource is a '<tt>/</tt>'-separated path name that
1062 * identifies the resource.
1063 *
1064 * <p> This method will first search the parent class loader for the
1065 * resource; if the parent is <tt>null</tt> the path of the class loader
1066 * built-in to the virtual machine is searched. That failing, this method
1067 * will invoke {@link #findResource(String)} to find the resource. </p>
1068 *
1069 * @apiNote When overriding this method it is recommended that an
1070 * implementation ensures that any delegation is consistent with the {@link
1071 * #getResources(java.lang.String) getResources(String)} method.
1072 *
1073 * @param name
1074 * The resource name
1075 *
1076 * @return A <tt>URL</tt> object for reading the resource, or
1077 * <tt>null</tt> if the resource could not be found or the invoker
1078 * doesn't have adequate privileges to get the resource.
1079 *
1080 * @since 1.1
1081 */
1082 public URL getResource(String name) {
1083 URL url;
1084 if (parent != null) {
1085 url = parent.getResource(name);
1086 } else {
1087 url = getBootstrapResource(name);
1088 }
1089 if (url == null) {
1090 url = findResource(name);
1091 }
1092 return url;
1093 }
1094
1095 /**
1096 * Finds all the resources with the given name. A resource is some data
1097 * (images, audio, text, etc) that can be accessed by class code in a way
1098 * that is independent of the location of the code.
1099 *
1100 * <p>The name of a resource is a <tt>/</tt>-separated path name that
1101 * identifies the resource.
1102 *
1103 * <p> The search order is described in the documentation for {@link
1104 * #getResource(String)}. </p>
1105 *
1106 * @apiNote When overriding this method it is recommended that an
1107 * implementation ensures that any delegation is consistent with the {@link
1108 * #getResource(java.lang.String) getResource(String)} method. This should
1109 * ensure that the first element returned by the Enumeration's
1110 * {@code nextElement} method is the same resource that the
1111 * {@code getResource(String)} method would return.
1112 *
1113 * @param name
1114 * The resource name
1115 *
1116 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1117 * the resource. If no resources could be found, the enumeration
1118 * will be empty. Resources that the class loader doesn't have
1119 * access to will not be in the enumeration.
1120 *
1121 * @throws IOException
1122 * If I/O errors occur
1123 *
1124 * @see #findResources(String)
1125 *
1126 * @since 1.2
1127 */
1128 public Enumeration<URL> getResources(String name) throws IOException {
1129 @SuppressWarnings("unchecked")
1130 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1131 if (parent != null) {
1132 tmp[0] = parent.getResources(name);
1133 } else {
1134 tmp[0] = getBootstrapResources(name);
1135 }
1136 tmp[1] = findResources(name);
1137
1138 return new CompoundEnumeration<>(tmp);
1139 }
1140
1141 /**
1142 * Finds the resource with the given name. Class loader implementations
1143 * should override this method to specify where to find resources.
1144 *
1145 * @param name
1146 * The resource name
1147 *
1148 * @return A <tt>URL</tt> object for reading the resource, or
1149 * <tt>null</tt> if the resource could not be found
1150 *
1151 * @since 1.2
1152 */
1153 protected URL findResource(String name) {
1154 return null;
1155 }
1156
1157 /**
1158 * Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
1159 * representing all the resources with the given name. Class loader
1160 * implementations should override this method to specify where to load
1161 * resources from.
1162 *
1163 * @param name
1164 * The resource name
1165 *
1166 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1167 * the resources
1168 *
1169 * @throws IOException
1170 * If I/O errors occur
1171 *
1172 * @since 1.2
1173 */
1174 protected Enumeration<URL> findResources(String name) throws IOException {
1175 return java.util.Collections.emptyEnumeration();
1176 }
1177
1178 /**
1179 * Registers the caller as parallel capable.
1180 * The registration succeeds if and only if all of the following
1181 * conditions are met:
1182 * <ol>
1183 * <li> no instance of the caller has been created</li>
1184 * <li> all of the super classes (except class Object) of the caller are
1185 * registered as parallel capable</li>
1186 * </ol>
1187 * <p>Note that once a class loader is registered as parallel capable, there
1188 * is no way to change it back.</p>
1189 *
1190 * @return true if the caller is successfully registered as
1191 * parallel capable and false if otherwise.
1192 *
1193 * @since 1.7
1194 */
1195 @CallerSensitive
1196 protected static boolean registerAsParallelCapable() {
1197 Class<? extends ClassLoader> callerClass =
1198 Reflection.getCallerClass().asSubclass(ClassLoader.class);
1199 return ParallelLoaders.register(callerClass);
1200 }
1201
1202 /**
1203 * Find a resource of the specified name from the search path used to load
1204 * classes. This method locates the resource through the system class
1205 * loader (see {@link #getSystemClassLoader()}).
1206 *
1207 * @param name
1208 * The resource name
1209 *
1210 * @return A {@link java.net.URL <tt>URL</tt>} object for reading the
1211 * resource, or <tt>null</tt> if the resource could not be found
1212 *
1213 * @since 1.1
1214 */
1215 public static URL getSystemResource(String name) {
1216 ClassLoader system = getSystemClassLoader();
1217 if (system == null) {
1218 return getBootstrapResource(name);
1219 }
1220 return system.getResource(name);
1221 }
1222
1223 /**
1224 * Finds all resources of the specified name from the search path used to
1225 * load classes. The resources thus found are returned as an
1226 * {@link java.util.Enumeration <tt>Enumeration</tt>} of {@link
1227 * java.net.URL <tt>URL</tt>} objects.
1228 *
1229 * <p> The search order is described in the documentation for {@link
1230 * #getSystemResource(String)}. </p>
1231 *
1232 * @param name
1233 * The resource name
1234 *
1235 * @return An enumeration of resource {@link java.net.URL <tt>URL</tt>}
1236 * objects
1237 *
1238 * @throws IOException
1239 * If I/O errors occur
1240
1241 * @since 1.2
1242 */
1243 public static Enumeration<URL> getSystemResources(String name)
1244 throws IOException
1245 {
1246 ClassLoader system = getSystemClassLoader();
1247 if (system == null) {
1248 return getBootstrapResources(name);
1249 }
1250 return system.getResources(name);
1251 }
1252
1253 /**
1254 * Find resources from the VM's built-in classloader.
1255 */
1256 private static URL getBootstrapResource(String name) {
1257 URLClassPath ucp = getBootstrapClassPath();
1258 Resource res = ucp.getResource(name);
1259 return res != null ? res.getURL() : null;
1260 }
1261
1262 /**
1263 * Find resources from the VM's built-in classloader.
1264 */
1265 private static Enumeration<URL> getBootstrapResources(String name)
1266 throws IOException
1267 {
1268 final Enumeration<Resource> e =
1269 getBootstrapClassPath().getResources(name);
1270 return new Enumeration<> () {
1271 public URL nextElement() {
1272 return e.nextElement().getURL();
1273 }
1274 public boolean hasMoreElements() {
1275 return e.hasMoreElements();
1276 }
1277 };
1278 }
1279
1280 // Returns the URLClassPath that is used for finding system resources.
1281 static URLClassPath getBootstrapClassPath() {
1282 return sun.misc.Launcher.getBootstrapClassPath();
1283 }
1284
1285
1286 /**
1287 * Returns an input stream for reading the specified resource.
1288 *
1289 * <p> The search order is described in the documentation for {@link
1290 * #getResource(String)}. </p>
1291 *
1292 * @param name
1293 * The resource name
1294 *
1295 * @return An input stream for reading the resource, or <tt>null</tt>
1296 * if the resource could not be found
1297 *
1298 * @since 1.1
1299 */
1300 public InputStream getResourceAsStream(String name) {
1301 URL url = getResource(name);
1302 try {
1303 return url != null ? url.openStream() : null;
1304 } catch (IOException e) {
1305 return null;
1306 }
1307 }
1308
1309 /**
1310 * Open for reading, a resource of the specified name from the search path
1311 * used to load classes. This method locates the resource through the
1312 * system class loader (see {@link #getSystemClassLoader()}).
1313 *
1314 * @param name
1315 * The resource name
1316 *
1317 * @return An input stream for reading the resource, or <tt>null</tt>
1318 * if the resource could not be found
1319 *
1320 * @since 1.1
1321 */
1322 public static InputStream getSystemResourceAsStream(String name) {
1323 URL url = getSystemResource(name);
1324 try {
1325 return url != null ? url.openStream() : null;
1326 } catch (IOException e) {
1327 return null;
1328 }
1329 }
1330
1331
1332 // -- Hierarchy --
1333
1334 /**
1335 * Returns the parent class loader for delegation. Some implementations may
1336 * use <tt>null</tt> to represent the bootstrap class loader. This method
1337 * will return <tt>null</tt> in such implementations if this class loader's
1338 * parent is the bootstrap class loader.
1339 *
1340 * <p> If a security manager is present, and the invoker's class loader is
1341 * not <tt>null</tt> and is not an ancestor of this class loader, then this
1342 * method invokes the security manager's {@link
1343 * SecurityManager#checkPermission(java.security.Permission)
1344 * <tt>checkPermission</tt>} method with a {@link
1345 * RuntimePermission#RuntimePermission(String)
1346 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1347 * access to the parent class loader is permitted. If not, a
1348 * <tt>SecurityException</tt> will be thrown. </p>
1349 *
1350 * @return The parent <tt>ClassLoader</tt>
1351 *
1352 * @throws SecurityException
1353 * If a security manager exists and its <tt>checkPermission</tt>
1354 * method doesn't allow access to this class loader's parent class
1355 * loader.
1356 *
1357 * @since 1.2
1358 */
1359 @CallerSensitive
1360 public final ClassLoader getParent() {
1361 if (parent == null)
1362 return null;
1363 SecurityManager sm = System.getSecurityManager();
1364 if (sm != null) {
1365 // Check access to the parent class loader
1366 // If the caller's class loader is same as this class loader,
1367 // permission check is performed.
1368 checkClassLoaderPermission(parent, Reflection.getCallerClass());
1369 }
1370 return parent;
1371 }
1372
1373 /**
1374 * Returns the system class loader for delegation. This is the default
1375 * delegation parent for new <tt>ClassLoader</tt> instances, and is
1376 * typically the class loader used to start the application.
1377 *
1378 * <p> This method is first invoked early in the runtime's startup
1379 * sequence, at which point it creates the system class loader and sets it
1380 * as the context class loader of the invoking <tt>Thread</tt>.
1381 *
1382 * <p> The default system class loader is an implementation-dependent
1383 * instance of this class.
1384 *
1385 * <p> If the system property "<tt>java.system.class.loader</tt>" is defined
1386 * when this method is first invoked then the value of that property is
1387 * taken to be the name of a class that will be returned as the system
1388 * class loader. The class is loaded using the default system class loader
1389 * and must define a public constructor that takes a single parameter of
1390 * type <tt>ClassLoader</tt> which is used as the delegation parent. An
1391 * instance is then created using this constructor with the default system
1392 * class loader as the parameter. The resulting class loader is defined
1393 * to be the system class loader.
1394 *
1395 * <p> If a security manager is present, and the invoker's class loader is
1396 * not <tt>null</tt> and the invoker's class loader is not the same as or
1397 * an ancestor of the system class loader, then this method invokes the
1398 * security manager's {@link
1399 * SecurityManager#checkPermission(java.security.Permission)
1400 * <tt>checkPermission</tt>} method with a {@link
1401 * RuntimePermission#RuntimePermission(String)
1402 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1403 * access to the system class loader. If not, a
1404 * <tt>SecurityException</tt> will be thrown. </p>
1405 *
1406 * @return The system <tt>ClassLoader</tt> for delegation, or
1407 * <tt>null</tt> if none
1408 *
1409 * @throws SecurityException
1410 * If a security manager exists and its <tt>checkPermission</tt>
1411 * method doesn't allow access to the system class loader.
1412 *
1413 * @throws IllegalStateException
1414 * If invoked recursively during the construction of the class
1415 * loader specified by the "<tt>java.system.class.loader</tt>"
1416 * property.
1417 *
1418 * @throws Error
1419 * If the system property "<tt>java.system.class.loader</tt>"
1420 * is defined but the named class could not be loaded, the
1421 * provider class does not define the required constructor, or an
1422 * exception is thrown by that constructor when it is invoked. The
1423 * underlying cause of the error can be retrieved via the
1424 * {@link Throwable#getCause()} method.
1425 *
1426 * @revised 1.4
1427 */
1428 @CallerSensitive
1429 public static ClassLoader getSystemClassLoader() {
1430 initSystemClassLoader();
1431 if (scl == null) {
1432 return null;
1433 }
1434 SecurityManager sm = System.getSecurityManager();
1435 if (sm != null) {
1436 checkClassLoaderPermission(scl, Reflection.getCallerClass());
1437 }
1438 return scl;
1439 }
1440
1441 private static synchronized void initSystemClassLoader() {
1442 if (!sclSet) {
1443 if (scl != null)
1444 throw new IllegalStateException("recursive invocation");
1445 sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
1446 if (l != null) {
1447 Throwable oops = null;
1448 scl = l.getClassLoader();
1449 try {
1450 scl = AccessController.doPrivileged(
1451 new SystemClassLoaderAction(scl));
1452 } catch (PrivilegedActionException pae) {
1453 oops = pae.getCause();
1454 if (oops instanceof InvocationTargetException) {
1455 oops = oops.getCause();
1456 }
1457 }
1458 if (oops != null) {
1459 if (oops instanceof Error) {
1460 throw (Error) oops;
1461 } else {
1462 // wrap the exception
1463 throw new Error(oops);
1464 }
1465 }
1466 }
1467 sclSet = true;
1468 }
1469 }
1470
1471 // Returns true if the specified class loader can be found in this class
1472 // loader's delegation chain.
1473 boolean isAncestor(ClassLoader cl) {
1474 ClassLoader acl = this;
1475 do {
1476 acl = acl.parent;
1477 if (cl == acl) {
1478 return true;
1479 }
1480 } while (acl != null);
1481 return false;
1482 }
1483
1484 // Tests if class loader access requires "getClassLoader" permission
1485 // check. A class loader 'from' can access class loader 'to' if
1486 // class loader 'from' is same as class loader 'to' or an ancestor
1487 // of 'to'. The class loader in a system domain can access
1488 // any class loader.
1489 private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
1490 ClassLoader to)
1491 {
1492 if (from == to)
1493 return false;
1494
1495 if (from == null)
1496 return false;
1497
1498 return !to.isAncestor(from);
1499 }
1500
1501 // Returns the class's class loader, or null if none.
1502 static ClassLoader getClassLoader(Class<?> caller) {
1503 // This can be null if the VM is requesting it
1504 if (caller == null) {
1505 return null;
1506 }
1507 // Circumvent security check since this is package-private
1508 return caller.getClassLoader0();
1509 }
1510
1511 /*
1512 * Checks RuntimePermission("getClassLoader") permission
1513 * if caller's class loader is not null and caller's class loader
1514 * is not the same as or an ancestor of the given cl argument.
1515 */
1516 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
1517 SecurityManager sm = System.getSecurityManager();
1518 if (sm != null) {
1519 // caller can be null if the VM is requesting it
1520 ClassLoader ccl = getClassLoader(caller);
1521 if (needsClassLoaderPermissionCheck(ccl, cl)) {
1522 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1523 }
1524 }
1525 }
1526
1527 // The class loader for the system
1528 // @GuardedBy("ClassLoader.class")
1529 private static ClassLoader scl;
1530
1531 // Set to true once the system class loader has been set
1532 // @GuardedBy("ClassLoader.class")
1533 private static boolean sclSet;
1534
1535
1536 // -- Package --
1537
1538 /**
1539 * Defines a package by name in this <tt>ClassLoader</tt>. This allows
1540 * class loaders to define the packages for their classes. Packages must
1541 * be created before the class is defined, and package names must be
1542 * unique within a class loader and cannot be redefined or changed once
1543 * created.
1544 *
1545 * @param name
1546 * The package name
1547 *
1548 * @param specTitle
1549 * The specification title
1550 *
1551 * @param specVersion
1552 * The specification version
1553 *
1554 * @param specVendor
1555 * The specification vendor
1556 *
1557 * @param implTitle
1558 * The implementation title
1559 *
1560 * @param implVersion
1561 * The implementation version
1562 *
1563 * @param implVendor
1564 * The implementation vendor
1565 *
1566 * @param sealBase
1567 * If not <tt>null</tt>, then this package is sealed with
1568 * respect to the given code source {@link java.net.URL
1569 * <tt>URL</tt>} object. Otherwise, the package is not sealed.
1570 *
1571 * @return The newly defined <tt>Package</tt> object
1572 *
1573 * @throws IllegalArgumentException
1574 * If package name duplicates an existing package either in this
1575 * class loader or one of its ancestors
1576 *
1577 * @since 1.2
1578 */
1579 protected Package definePackage(String name, String specTitle,
1580 String specVersion, String specVendor,
1581 String implTitle, String implVersion,
1582 String implVendor, URL sealBase)
1583 throws IllegalArgumentException
1584 {
1585 Package pkg = getPackage(name);
1586 if (pkg != null) {
1587 throw new IllegalArgumentException(name);
1588 }
1589 pkg = new Package(name, specTitle, specVersion, specVendor,
1590 implTitle, implVersion, implVendor,
1591 sealBase, this);
1592 if (packages.putIfAbsent(name, pkg) != null) {
1593 throw new IllegalArgumentException(name);
1594 }
1595 return pkg;
1596 }
1597
1598 /**
1599 * Returns a <tt>Package</tt> that has been defined by this class loader
1600 * or any of its ancestors.
1601 *
1602 * @param name
1603 * The package name
1604 *
1605 * @return The <tt>Package</tt> corresponding to the given name, or
1606 * <tt>null</tt> if not found
1607 *
1608 * @since 1.2
1609 */
1610 protected Package getPackage(String name) {
1611 Package pkg = packages.get(name);
1612 if (pkg == null) {
1613 if (parent != null) {
1614 pkg = parent.getPackage(name);
1615 } else {
1616 pkg = Package.getSystemPackage(name);
1617 }
1618 }
1619 return pkg;
1620 }
1621
1622 /**
1623 * Returns all of the <tt>Packages</tt> defined by this class loader and
1624 * its ancestors.
1625 *
1626 * @return The array of <tt>Package</tt> objects defined by this
1627 * <tt>ClassLoader</tt>
1628 *
1629 * @since 1.2
1630 */
1631 protected Package[] getPackages() {
1632 Package[] pkgs;
1633 if (parent != null) {
1634 pkgs = parent.getPackages();
1635 } else {
1636 pkgs = Package.getSystemPackages();
1637 }
1638
1639 Map<String, Package> map = packages;
1640 if (pkgs != null) {
1641 map = new HashMap<>(packages);
1642 for (Package pkg : pkgs) {
1643 map.putIfAbsent(pkg.getName(), pkg);
1644 }
1645 }
1646 return map.values().toArray(new Package[map.size()]);
1647 }
1648
1649
1650 // -- Native library access --
1651
1652 /**
1653 * Returns the absolute path name of a native library. The VM invokes this
1654 * method to locate the native libraries that belong to classes loaded with
1655 * this class loader. If this method returns <tt>null</tt>, the VM
1656 * searches the library along the path specified as the
1657 * "<tt>java.library.path</tt>" property.
1658 *
1659 * @param libname
1660 * The library name
1661 *
1662 * @return The absolute path of the native library
1663 *
1664 * @see System#loadLibrary(String)
1665 * @see System#mapLibraryName(String)
1666 *
1667 * @since 1.2
1668 */
1669 protected String findLibrary(String libname) {
1670 return null;
1671 }
1672
1673 /**
1674 * The inner class NativeLibrary denotes a loaded native library instance.
1675 * Every classloader contains a vector of loaded native libraries in the
1676 * private field <tt>nativeLibraries</tt>. The native libraries loaded
1677 * into the system are entered into the <tt>systemNativeLibraries</tt>
1678 * vector.
1679 *
1680 * <p> Every native library requires a particular version of JNI. This is
1681 * denoted by the private <tt>jniVersion</tt> field. This field is set by
1682 * the VM when it loads the library, and used by the VM to pass the correct
1683 * version of JNI to the native methods. </p>
1684 *
1685 * @see ClassLoader
1686 * @since 1.2
1687 */
1688 static class NativeLibrary {
1689 // opaque handle to native library, used in native code.
1690 long handle;
1691 // the version of JNI environment the native library requires.
1692 private int jniVersion;
1693 // the class from which the library is loaded, also indicates
1694 // the loader this native library belongs.
1695 private final Class<?> fromClass;
1696 // the canonicalized name of the native library.
1697 // or static library name
1698 String name;
1699 // Indicates if the native library is linked into the VM
1700 boolean isBuiltin;
1701 // Indicates if the native library is loaded
1702 boolean loaded;
1703 native void load(String name, boolean isBuiltin);
1704
1705 native long find(String name);
1706 native void unload(String name, boolean isBuiltin);
1707
1708 public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
1709 this.name = name;
1710 this.fromClass = fromClass;
1711 this.isBuiltin = isBuiltin;
1712 }
1713
1714 protected void finalize() {
1715 synchronized (loadedLibraryNames) {
1716 if (fromClass.getClassLoader() != null && loaded) {
1717 /* remove the native library name */
1718 int size = loadedLibraryNames.size();
1719 for (int i = 0; i < size; i++) {
1720 if (name.equals(loadedLibraryNames.elementAt(i))) {
1721 loadedLibraryNames.removeElementAt(i);
1722 break;
1723 }
1724 }
1725 /* unload the library. */
1726 ClassLoader.nativeLibraryContext.push(this);
1727 try {
1728 unload(name, isBuiltin);
1729 } finally {
1730 ClassLoader.nativeLibraryContext.pop();
1731 }
1732 }
1733 }
1734 }
1735 // Invoked in the VM to determine the context class in
1736 // JNI_Load/JNI_Unload
1737 static Class<?> getFromClass() {
1738 return ClassLoader.nativeLibraryContext.peek().fromClass;
1739 }
1740 }
1741
1742 // All native library names we've loaded.
1743 private static Vector<String> loadedLibraryNames = new Vector<>();
1744
1745 // Native libraries belonging to system classes.
1746 private static Vector<NativeLibrary> systemNativeLibraries
1747 = new Vector<>();
1748
1749 // Native libraries associated with the class loader.
1750 private Vector<NativeLibrary> nativeLibraries = new Vector<>();
1751
1752 // native libraries being loaded/unloaded.
1753 private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>();
1754
1755 // The paths searched for libraries
1756 private static String usr_paths[];
1757 private static String sys_paths[];
1758
1759 private static String[] initializePath(String propName) {
1760 String ldPath = System.getProperty(propName, "");
1761 int ldLen = ldPath.length();
1762 char ps = File.pathSeparatorChar;
1763 int psCount = 0;
1764
1765 if (ClassLoaderHelper.allowsQuotedPathElements &&
1766 ldPath.indexOf('\"') >= 0) {
1767 // First, remove quotes put around quoted parts of paths.
1768 // Second, use a quotation mark as a new path separator.
1769 // This will preserve any quoted old path separators.
1770 char[] buf = new char[ldLen];
1771 int bufLen = 0;
1772 for (int i = 0; i < ldLen; ++i) {
1773 char ch = ldPath.charAt(i);
1774 if (ch == '\"') {
1775 while (++i < ldLen &&
1776 (ch = ldPath.charAt(i)) != '\"') {
1777 buf[bufLen++] = ch;
1778 }
1779 } else {
1780 if (ch == ps) {
1781 psCount++;
1782 ch = '\"';
1783 }
1784 buf[bufLen++] = ch;
1785 }
1786 }
1787 ldPath = new String(buf, 0, bufLen);
1788 ldLen = bufLen;
1789 ps = '\"';
1790 } else {
1791 for (int i = ldPath.indexOf(ps); i >= 0;
1792 i = ldPath.indexOf(ps, i + 1)) {
1793 psCount++;
1794 }
1795 }
1796
1797 String[] paths = new String[psCount + 1];
1798 int pathStart = 0;
1799 for (int j = 0; j < psCount; ++j) {
1800 int pathEnd = ldPath.indexOf(ps, pathStart);
1801 paths[j] = (pathStart < pathEnd) ?
1802 ldPath.substring(pathStart, pathEnd) : ".";
1803 pathStart = pathEnd + 1;
1804 }
1805 paths[psCount] = (pathStart < ldLen) ?
1806 ldPath.substring(pathStart, ldLen) : ".";
1807 return paths;
1808 }
1809
1810 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
1811 static void loadLibrary(Class<?> fromClass, String name,
1812 boolean isAbsolute) {
1813 ClassLoader loader =
1814 (fromClass == null) ? null : fromClass.getClassLoader();
1815 if (sys_paths == null) {
1816 usr_paths = initializePath("java.library.path");
1817 sys_paths = initializePath("sun.boot.library.path");
1818 }
1819 if (isAbsolute) {
1820 if (loadLibrary0(fromClass, new File(name))) {
1821 return;
1822 }
1823 throw new UnsatisfiedLinkError("Can't load library: " + name);
1824 }
1825 if (loader != null) {
1826 String libfilename = loader.findLibrary(name);
1827 if (libfilename != null) {
1828 File libfile = new File(libfilename);
1829 if (!libfile.isAbsolute()) {
1830 throw new UnsatisfiedLinkError(
1831 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
1832 }
1833 if (loadLibrary0(fromClass, libfile)) {
1834 return;
1835 }
1836 throw new UnsatisfiedLinkError("Can't load " + libfilename);
1837 }
1838 }
1839 for (String sys_path : sys_paths) {
1840 File libfile = new File(sys_path, System.mapLibraryName(name));
1841 if (loadLibrary0(fromClass, libfile)) {
1842 return;
1843 }
1844 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
1845 if (libfile != null && loadLibrary0(fromClass, libfile)) {
1846 return;
1847 }
1848 }
1849 if (loader != null) {
1850 for (String usr_path : usr_paths) {
1851 File libfile = new File(usr_path, System.mapLibraryName(name));
1852 if (loadLibrary0(fromClass, libfile)) {
1853 return;
1854 }
1855 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
1856 if (libfile != null && loadLibrary0(fromClass, libfile)) {
1857 return;
1858 }
1859 }
1860 }
1861 // Oops, it failed
1862 throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
1863 }
1864
1865 static native String findBuiltinLib(String name);
1866
1867 private static boolean loadLibrary0(Class<?> fromClass, final File file) {
1868 // Check to see if we're attempting to access a static library
1869 String name = findBuiltinLib(file.getName());
1870 boolean isBuiltin = (name != null);
1871 if (!isBuiltin) {
1872 name = AccessController.doPrivileged(
1873 new PrivilegedAction<>() {
1874 public String run() {
1875 try {
1876 return file.exists() ? file.getCanonicalPath() : null;
1877 } catch (IOException e) {
1878 return null;
1879 }
1880 }
1881 });
1882 if (name == null) {
1883 return false;
1884 }
1885 }
1886 ClassLoader loader =
1887 (fromClass == null) ? null : fromClass.getClassLoader();
1888 Vector<NativeLibrary> libs =
1889 loader != null ? loader.nativeLibraries : systemNativeLibraries;
1890 synchronized (libs) {
1891 int size = libs.size();
1892 for (int i = 0; i < size; i++) {
1893 NativeLibrary lib = libs.elementAt(i);
1894 if (name.equals(lib.name)) {
1895 return true;
1896 }
1897 }
1898
1899 synchronized (loadedLibraryNames) {
1900 if (loadedLibraryNames.contains(name)) {
1901 throw new UnsatisfiedLinkError
1902 ("Native Library " +
1903 name +
1904 " already loaded in another classloader");
1905 }
1906 /* If the library is being loaded (must be by the same thread,
1907 * because Runtime.load and Runtime.loadLibrary are
1908 * synchronous). The reason is can occur is that the JNI_OnLoad
1909 * function can cause another loadLibrary invocation.
1910 *
1911 * Thus we can use a static stack to hold the list of libraries
1912 * we are loading.
1913 *
1914 * If there is a pending load operation for the library, we
1915 * immediately return success; otherwise, we raise
1916 * UnsatisfiedLinkError.
1917 */
1918 int n = nativeLibraryContext.size();
1919 for (int i = 0; i < n; i++) {
1920 NativeLibrary lib = nativeLibraryContext.elementAt(i);
1921 if (name.equals(lib.name)) {
1922 if (loader == lib.fromClass.getClassLoader()) {
1923 return true;
1924 } else {
1925 throw new UnsatisfiedLinkError
1926 ("Native Library " +
1927 name +
1928 " is being loaded in another classloader");
1929 }
1930 }
1931 }
1932 NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
1933 nativeLibraryContext.push(lib);
1934 try {
1935 lib.load(name, isBuiltin);
1936 } finally {
1937 nativeLibraryContext.pop();
1938 }
1939 if (lib.loaded) {
1940 loadedLibraryNames.addElement(name);
1941 libs.addElement(lib);
1942 return true;
1943 }
1944 return false;
1945 }
1946 }
1947 }
1948
1949 // Invoked in the VM class linking code.
1950 static long findNative(ClassLoader loader, String name) {
1951 Vector<NativeLibrary> libs =
1952 loader != null ? loader.nativeLibraries : systemNativeLibraries;
1953 synchronized (libs) {
1954 int size = libs.size();
1955 for (int i = 0; i < size; i++) {
1956 NativeLibrary lib = libs.elementAt(i);
1957 long entry = lib.find(name);
1958 if (entry != 0)
1959 return entry;
1960 }
1961 }
1962 return 0;
1963 }
1964
1965
1966 // -- Assertion management --
1967
1968 final Object assertionLock;
1969
1970 // The default toggle for assertion checking.
1971 // @GuardedBy("assertionLock")
1972 private boolean defaultAssertionStatus = false;
1973
1974 // Maps String packageName to Boolean package default assertion status Note
1975 // that the default package is placed under a null map key. If this field
1976 // is null then we are delegating assertion status queries to the VM, i.e.,
1977 // none of this ClassLoader's assertion status modification methods have
1978 // been invoked.
1979 // @GuardedBy("assertionLock")
1980 private Map<String, Boolean> packageAssertionStatus = null;
1981
1982 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
1983 // field is null then we are delegating assertion status queries to the VM,
1984 // i.e., none of this ClassLoader's assertion status modification methods
1985 // have been invoked.
1986 // @GuardedBy("assertionLock")
1987 Map<String, Boolean> classAssertionStatus = null;
1988
1989 /**
1990 * Sets the default assertion status for this class loader. This setting
1991 * determines whether classes loaded by this class loader and initialized
1992 * in the future will have assertions enabled or disabled by default.
1993 * This setting may be overridden on a per-package or per-class basis by
1994 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
1995 * #setClassAssertionStatus(String, boolean)}.
1996 *
1997 * @param enabled
1998 * <tt>true</tt> if classes loaded by this class loader will
1999 * henceforth have assertions enabled by default, <tt>false</tt>
2000 * if they will have assertions disabled by default.
2001 *
2002 * @since 1.4
2003 */
2004 public void setDefaultAssertionStatus(boolean enabled) {
2005 synchronized (assertionLock) {
2006 if (classAssertionStatus == null)
2007 initializeJavaAssertionMaps();
2008
2009 defaultAssertionStatus = enabled;
2010 }
2011 }
2012
2013 /**
2014 * Sets the package default assertion status for the named package. The
2015 * package default assertion status determines the assertion status for
2016 * classes initialized in the future that belong to the named package or
2017 * any of its "subpackages".
2018 *
2019 * <p> A subpackage of a package named p is any package whose name begins
2020 * with "<tt>p.</tt>". For example, <tt>javax.swing.text</tt> is a
2021 * subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt> and
2022 * <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
2023 *
2024 * <p> In the event that multiple package defaults apply to a given class,
2025 * the package default pertaining to the most specific package takes
2026 * precedence over the others. For example, if <tt>javax.lang</tt> and
2027 * <tt>javax.lang.reflect</tt> both have package defaults associated with
2028 * them, the latter package default applies to classes in
2029 * <tt>javax.lang.reflect</tt>.
2030 *
2031 * <p> Package defaults take precedence over the class loader's default
2032 * assertion status, and may be overridden on a per-class basis by invoking
2033 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2034 *
2035 * @param packageName
2036 * The name of the package whose package default assertion status
2037 * is to be set. A <tt>null</tt> value indicates the unnamed
2038 * package that is "current"
2039 * (see section 7.4.2 of
2040 * <cite>The Java™ Language Specification</cite>.)
2041 *
2042 * @param enabled
2043 * <tt>true</tt> if classes loaded by this classloader and
2044 * belonging to the named package or any of its subpackages will
2045 * have assertions enabled by default, <tt>false</tt> if they will
2046 * have assertions disabled by default.
2047 *
2048 * @since 1.4
2049 */
2050 public void setPackageAssertionStatus(String packageName,
2051 boolean enabled) {
2052 synchronized (assertionLock) {
2053 if (packageAssertionStatus == null)
2054 initializeJavaAssertionMaps();
2055
2056 packageAssertionStatus.put(packageName, enabled);
2057 }
2058 }
2059
2060 /**
2061 * Sets the desired assertion status for the named top-level class in this
2062 * class loader and any nested classes contained therein. This setting
2063 * takes precedence over the class loader's default assertion status, and
2064 * over any applicable per-package default. This method has no effect if
2065 * the named class has already been initialized. (Once a class is
2066 * initialized, its assertion status cannot change.)
2067 *
2068 * <p> If the named class is not a top-level class, this invocation will
2069 * have no effect on the actual assertion status of any class. </p>
2070 *
2071 * @param className
2072 * The fully qualified class name of the top-level class whose
2073 * assertion status is to be set.
2074 *
2075 * @param enabled
2076 * <tt>true</tt> if the named class is to have assertions
2077 * enabled when (and if) it is initialized, <tt>false</tt> if the
2078 * class is to have assertions disabled.
2079 *
2080 * @since 1.4
2081 */
2082 public void setClassAssertionStatus(String className, boolean enabled) {
2083 synchronized (assertionLock) {
2084 if (classAssertionStatus == null)
2085 initializeJavaAssertionMaps();
2086
2087 classAssertionStatus.put(className, enabled);
2088 }
2089 }
2090
2091 /**
2092 * Sets the default assertion status for this class loader to
2093 * <tt>false</tt> and discards any package defaults or class assertion
2094 * status settings associated with the class loader. This method is
2095 * provided so that class loaders can be made to ignore any command line or
2096 * persistent assertion status settings and "start with a clean slate."
2097 *
2098 * @since 1.4
2099 */
2100 public void clearAssertionStatus() {
2101 /*
2102 * Whether or not "Java assertion maps" are initialized, set
2103 * them to empty maps, effectively ignoring any present settings.
2104 */
2105 synchronized (assertionLock) {
2106 classAssertionStatus = new HashMap<>();
2107 packageAssertionStatus = new HashMap<>();
2108 defaultAssertionStatus = false;
2109 }
2110 }
2111
2112 /**
2113 * Returns the assertion status that would be assigned to the specified
2114 * class if it were to be initialized at the time this method is invoked.
2115 * If the named class has had its assertion status set, the most recent
2116 * setting will be returned; otherwise, if any package default assertion
2117 * status pertains to this class, the most recent setting for the most
2118 * specific pertinent package default assertion status is returned;
2119 * otherwise, this class loader's default assertion status is returned.
2120 * </p>
2121 *
2122 * @param className
2123 * The fully qualified class name of the class whose desired
2124 * assertion status is being queried.
2125 *
2126 * @return The desired assertion status of the specified class.
2127 *
2128 * @see #setClassAssertionStatus(String, boolean)
2129 * @see #setPackageAssertionStatus(String, boolean)
2130 * @see #setDefaultAssertionStatus(boolean)
2131 *
2132 * @since 1.4
2133 */
2134 boolean desiredAssertionStatus(String className) {
2135 synchronized (assertionLock) {
2136 // assert classAssertionStatus != null;
2137 // assert packageAssertionStatus != null;
2138
2139 // Check for a class entry
2140 Boolean result = classAssertionStatus.get(className);
2141 if (result != null)
2142 return result.booleanValue();
2143
2144 // Check for most specific package entry
2145 int dotIndex = className.lastIndexOf('.');
2146 if (dotIndex < 0) { // default package
2147 result = packageAssertionStatus.get(null);
2148 if (result != null)
2149 return result.booleanValue();
2150 }
2151 while(dotIndex > 0) {
2152 className = className.substring(0, dotIndex);
2153 result = packageAssertionStatus.get(className);
2154 if (result != null)
2155 return result.booleanValue();
2156 dotIndex = className.lastIndexOf('.', dotIndex-1);
2157 }
2158
2159 // Return the classloader default
2160 return defaultAssertionStatus;
2161 }
2162 }
2163
2164 // Set up the assertions with information provided by the VM.
2165 // Note: Should only be called inside a synchronized block
2166 private void initializeJavaAssertionMaps() {
2167 // assert Thread.holdsLock(assertionLock);
2168
2169 classAssertionStatus = new HashMap<>();
2170 packageAssertionStatus = new HashMap<>();
2171 AssertionStatusDirectives directives = retrieveDirectives();
2172
2173 for(int i = 0; i < directives.classes.length; i++)
2174 classAssertionStatus.put(directives.classes[i],
2175 directives.classEnabled[i]);
2176
2177 for(int i = 0; i < directives.packages.length; i++)
2178 packageAssertionStatus.put(directives.packages[i],
2179 directives.packageEnabled[i]);
2180
2181 defaultAssertionStatus = directives.deflt;
2182 }
2183
2184 // Retrieves the assertion directives from the VM.
2185 private static native AssertionStatusDirectives retrieveDirectives();
2186 }
2187
2188
2189 class SystemClassLoaderAction
2190 implements PrivilegedExceptionAction<ClassLoader> {
2191 private ClassLoader parent;
2192
2193 SystemClassLoaderAction(ClassLoader parent) {
2194 this.parent = parent;
2195 }
2196
2197 public ClassLoader run() throws Exception {
2198 String cls = System.getProperty("java.system.class.loader");
2199 if (cls == null) {
2200 return parent;
2201 }
2202
2203 Constructor<?> ctor = Class.forName(cls, true, parent)
2204 .getDeclaredConstructor(new Class<?>[] { ClassLoader.class });
2205 ClassLoader sys = (ClassLoader) ctor.newInstance(
2206 new Object[] { parent });
2207 Thread.currentThread().setContextClassLoader(sys);
2208 return sys;
2209 }
2210 }
2211
2212 /*
2213 * A utility class that will enumerate over an array of enumerations.
2214 */
2215 final class CompoundEnumeration<E> implements Enumeration<E> {
2216 private final Enumeration<E>[] enums;
2217 private int index;
2218
2219 public CompoundEnumeration(Enumeration<E>[] enums) {
2220 this.enums = enums;
2221 }
2222
2223 private boolean next() {
2224 while (index < enums.length) {
2225 if (enums[index] != null && enums[index].hasMoreElements()) {
2226 return true;
2227 }
2228 index++;
2229 }
2230 return false;
2231 }
2232
2233 public boolean hasMoreElements() {
2234 return next();
2235 }
2236
2237 public E nextElement() {
2238 if (!next()) {
2239 throw new NoSuchElementException();
2240 }
2241 return enums[index].nextElement();
2242 }
2243 }