1 /*
2 * Copyright 1994-2005 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any 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.MalformedURLException;
33 import java.net.URL;
34 import java.security.AccessController;
35 import java.security.AccessControlContext;
36 import java.security.CodeSource;
37 import java.security.Policy;
38 import java.security.PrivilegedAction;
39 import java.security.PrivilegedActionException;
40 import java.security.PrivilegedExceptionAction;
41 import java.security.ProtectionDomain;
42 import java.security.cert.Certificate;
43 import java.util.Enumeration;
44 import java.util.Hashtable;
45 import java.util.HashMap;
46 import java.util.HashSet;
47 import java.util.Set;
48 import java.util.Stack;
49 import java.util.Map;
50 import java.util.Vector;
51 import sun.misc.ClassFileTransformer;
52 import sun.misc.CompoundEnumeration;
53 import sun.misc.Resource;
54 import sun.misc.URLClassPath;
55 import sun.misc.VM;
56 import sun.reflect.Reflection;
57 import sun.security.util.SecurityConstants;
58
59 /**
60 * A class loader is an object that is responsible for loading classes. The
61 * class <tt>ClassLoader</tt> is an abstract class. Given the <a
62 * href="#name">binary name</a> of a class, a class loader should attempt to
63 * locate or generate data that constitutes a definition for the class. A
64 * typical strategy is to transform the name into a file name and then read a
65 * "class file" of that name from a file system.
66 *
67 * <p> Every {@link Class <tt>Class</tt>} object contains a {@link
68 * Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
69 * it.
70 *
71 * <p> <tt>Class</tt> objects for array classes are not created by class
72 * loaders, but are created automatically as required by the Java runtime.
73 * The class loader for an array class, as returned by {@link
74 * Class#getClassLoader()} is the same as the class loader for its element
75 * type; if the element type is a primitive type, then the array class has no
76 * class loader.
77 *
78 * <p> Applications implement subclasses of <tt>ClassLoader</tt> in order to
79 * extend the manner in which the Java virtual machine dynamically loads
80 * classes.
81 *
82 * <p> Class loaders may typically be used by security managers to indicate
83 * security domains.
84 *
85 * <p> The <tt>ClassLoader</tt> class uses a delegation model to search for
86 * classes and resources. Each instance of <tt>ClassLoader</tt> has an
87 * associated parent class loader. When requested to find a class or
88 * resource, a <tt>ClassLoader</tt> instance will delegate the search for the
89 * class or resource to its parent class loader before attempting to find the
90 * class or resource itself. The virtual machine's built-in class loader,
91 * called the "bootstrap class loader", does not itself have a parent but may
92 * serve as the parent of a <tt>ClassLoader</tt> instance.
93 *
94 * <p> Normally, the Java virtual machine loads classes from the local file
95 * system in a platform-dependent manner. For example, on UNIX systems, the
96 * virtual machine loads classes from the directory defined by the
97 * <tt>CLASSPATH</tt> environment variable.
98 *
99 * <p> However, some classes may not originate from a file; they may originate
100 * from other sources, such as the network, or they could be constructed by an
101 * application. The method {@link #defineClass(String, byte[], int, int)
102 * <tt>defineClass</tt>} converts an array of bytes into an instance of class
103 * <tt>Class</tt>. Instances of this newly defined class can be created using
104 * {@link Class#newInstance <tt>Class.newInstance</tt>}.
105 *
106 * <p> The methods and constructors of objects created by a class loader may
107 * reference other classes. To determine the class(es) referred to, the Java
108 * virtual machine invokes the {@link #loadClass <tt>loadClass</tt>} method of
109 * the class loader that originally created the class.
110 *
111 * <p> For example, an application could create a network class loader to
112 * download class files from a server. Sample code might look like:
113 *
114 * <blockquote><pre>
115 * ClassLoader loader = new NetworkClassLoader(host, port);
116 * Object main = loader.loadClass("Main", true).newInstance();
117 * . . .
118 * </pre></blockquote>
119 *
120 * <p> The network class loader subclass must define the methods {@link
121 * #findClass <tt>findClass</tt>} and <tt>loadClassData</tt> to load a class
122 * from the network. Once it has downloaded the bytes that make up the class,
123 * it should use the method {@link #defineClass <tt>defineClass</tt>} to
124 * create a class instance. A sample implementation is:
125 *
126 * <blockquote><pre>
127 * class NetworkClassLoader extends ClassLoader {
128 * String host;
129 * int port;
130 *
131 * public Class findClass(String name) {
132 * byte[] b = loadClassData(name);
133 * return defineClass(name, b, 0, b.length);
134 * }
135 *
136 * private byte[] loadClassData(String name) {
137 * // load the class data from the connection
138 * . . .
139 * }
140 * }
141 * </pre></blockquote>
142 *
143 * <h4> <a name="name">Binary names</a> </h4>
144 *
145 * <p> Any class name provided as a {@link String} parameter to methods in
146 * <tt>ClassLoader</tt> must be a binary name as defined by the <a
147 * href="http://java.sun.com/docs/books/jls/">Java Language Specification</a>.
148 *
149 * <p> Examples of valid class names include:
150 * <blockquote><pre>
151 * "java.lang.String"
152 * "javax.swing.JSpinner$DefaultEditor"
153 * "java.security.KeyStore$Builder$FileBuilder$1"
154 * "java.net.URLClassLoader$3$1"
155 * </pre></blockquote>
156 *
157 * @see #resolveClass(Class)
158 * @since 1.0
159 */
160 public abstract class ClassLoader {
161
162 private static native void registerNatives();
163 static {
164 registerNatives();
165 }
166
167 // If initialization succeed this is set to true and security checks will
168 // succeed. Otherwise the object is not initialized and the object is
169 // useless.
170 private boolean initialized = false;
171
172 // The parent class loader for delegation
173 private ClassLoader parent;
174
175 // Hashtable that maps packages to certs
176 private Hashtable<String, Certificate[]> package2certs
177 = new Hashtable<String, Certificate[]>(11);
178
179 // Shared among all packages with unsigned classes
180 Certificate[] nocerts;
181
182 // The classes loaded by this class loader. The only purpose of this table
183 // is to keep the classes from being GC'ed until the loader is GC'ed.
184 private Vector<Class<?>> classes = new Vector<Class<?>>();
185
186 // The initiating protection domains for all classes loaded by this loader
187 private Set<ProtectionDomain> domains = new HashSet<ProtectionDomain>();
188
189 // Invoked by the VM to record every loaded class with this loader.
190 void addClass(Class c) {
191 classes.addElement(c);
192 }
193
194 // The packages defined in this class loader. Each package name is mapped
195 // to its corresponding Package object.
196 private HashMap<String, Package> packages = new HashMap<String, Package>();
197
198 /**
199 * Creates a new class loader using the specified parent class loader for
200 * delegation.
201 *
202 * <p> If there is a security manager, its {@link
203 * SecurityManager#checkCreateClassLoader()
204 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
205 * a security exception. </p>
206 *
207 * @param parent
208 * The parent class loader
209 *
210 * @throws SecurityException
211 * If a security manager exists and its
212 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
213 * of a new class loader.
214 *
215 * @since 1.2
216 */
217 protected ClassLoader(ClassLoader parent) {
218 SecurityManager security = System.getSecurityManager();
219 if (security != null) {
220 security.checkCreateClassLoader();
221 }
222 this.parent = parent;
223 initialized = true;
224 }
225
226 /**
227 * Creates a new class loader using the <tt>ClassLoader</tt> returned by
228 * the method {@link #getSystemClassLoader()
229 * <tt>getSystemClassLoader()</tt>} as the parent class loader.
230 *
231 * <p> If there is a security manager, its {@link
232 * SecurityManager#checkCreateClassLoader()
233 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
234 * a security exception. </p>
235 *
236 * @throws SecurityException
237 * If a security manager exists and its
238 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
239 * of a new class loader.
240 */
241 protected ClassLoader() {
242 SecurityManager security = System.getSecurityManager();
243 if (security != null) {
244 security.checkCreateClassLoader();
245 }
246 this.parent = getSystemClassLoader();
247 initialized = true;
248 }
249
250
251 // -- Class --
252
253 /**
254 * Loads the class with the specified <a href="#name">binary name</a>.
255 * This method searches for classes in the same manner as the {@link
256 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
257 * machine to resolve class references. Invoking this method is equivalent
258 * to invoking {@link #loadClass(String, boolean) <tt>loadClass(name,
259 * false)</tt>}. </p>
260 *
261 * @param name
262 * The <a href="#name">binary name</a> of the class
263 *
264 * @return The resulting <tt>Class</tt> object
265 *
266 * @throws ClassNotFoundException
267 * If the class was not found
268 */
269 public Class<?> loadClass(String name) throws ClassNotFoundException {
270 return loadClass(name, false);
271 }
272
273 /**
274 * Loads the class with the specified <a href="#name">binary name</a>. The
275 * default implementation of this method searches for classes in the
276 * following order:
277 *
278 * <p><ol>
279 *
280 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
281 * has already been loaded. </p></li>
282 *
283 * <li><p> Invoke the {@link #loadClass(String) <tt>loadClass</tt>} method
284 * on the parent class loader. If the parent is <tt>null</tt> the class
285 * loader built-in to the virtual machine is used, instead. </p></li>
286 *
287 * <li><p> Invoke the {@link #findClass(String)} method to find the
288 * class. </p></li>
289 *
290 * </ol>
291 *
292 * <p> If the class was found using the above steps, and the
293 * <tt>resolve</tt> flag is true, this method will then invoke the {@link
294 * #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
295 *
296 * <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
297 * #findClass(String)}, rather than this method. </p>
298 *
299 * @param name
300 * The <a href="#name">binary name</a> of the class
301 *
302 * @param resolve
303 * If <tt>true</tt> then resolve the class
304 *
305 * @return The resulting <tt>Class</tt> object
306 *
307 * @throws ClassNotFoundException
308 * If the class could not be found
309 */
310 protected synchronized Class<?> loadClass(String name, boolean resolve)
311 throws ClassNotFoundException
312 {
313 // First, check if the class has already been loaded
314 Class c = findLoadedClass(name);
315 if (c == null) {
316 try {
317 if (parent != null) {
318 c = parent.loadClass(name, false);
319 } else {
320 c = findBootstrapClass0(name);
321 }
322 } catch (ClassNotFoundException e) {
323 // If still not found, then invoke findClass in order
324 // to find the class.
325 c = findClass(name);
326 }
327 }
328 if (resolve) {
329 resolveClass(c);
330 }
331 return c;
332 }
333
334 // This method is invoked by the virtual machine to load a class.
335 private synchronized Class loadClassInternal(String name)
336 throws ClassNotFoundException
337 {
338 return loadClass(name);
339 }
340
341 private void checkPackageAccess(Class cls, ProtectionDomain pd) {
342 final SecurityManager sm = System.getSecurityManager();
343 if (sm != null) {
344 final String name = cls.getName();
345 final int i = name.lastIndexOf('.');
346 if (i != -1) {
347 AccessController.doPrivileged(new PrivilegedAction<Void>() {
348 public Void run() {
349 sm.checkPackageAccess(name.substring(0, i));
350 return null;
351 }
352 }, new AccessControlContext(new ProtectionDomain[] {pd}));
353 }
354 }
355 domains.add(pd);
356 }
357
358 /**
359 * Finds the class with the specified <a href="#name">binary name</a>.
360 * This method should be overridden by class loader implementations that
361 * follow the delegation model for loading classes, and will be invoked by
362 * the {@link #loadClass <tt>loadClass</tt>} method after checking the
363 * parent class loader for the requested class. The default implementation
364 * throws a <tt>ClassNotFoundException</tt>. </p>
365 *
366 * @param name
367 * The <a href="#name">binary name</a> of the class
368 *
369 * @return The resulting <tt>Class</tt> object
370 *
371 * @throws ClassNotFoundException
372 * If the class could not be found
373 *
374 * @since 1.2
375 */
376 protected Class<?> findClass(String name) throws ClassNotFoundException {
377 throw new ClassNotFoundException(name);
378 }
379
380 /**
381 * Converts an array of bytes into an instance of class <tt>Class</tt>.
382 * Before the <tt>Class</tt> can be used it must be resolved. This method
383 * is deprecated in favor of the version that takes a <a
384 * href="#name">binary name</a> as its first argument, and is more secure.
385 *
386 * @param b
387 * The bytes that make up the class data. The bytes in positions
388 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
389 * of a valid class file as defined by the <a
390 * href="http://java.sun.com/docs/books/vmspec/">Java Virtual
391 * Machine Specification</a>.
392 *
393 * @param off
394 * The start offset in <tt>b</tt> of the class data
395 *
396 * @param len
397 * The length of the class data
398 *
399 * @return The <tt>Class</tt> object that was created from the specified
400 * class data
401 *
402 * @throws ClassFormatError
403 * If the data did not contain a valid class
404 *
405 * @throws IndexOutOfBoundsException
406 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
407 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
408 *
409 * @see #loadClass(String, boolean)
410 * @see #resolveClass(Class)
411 *
412 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
413 * defineClass(String, byte[], int, int)}
414 */
415 @Deprecated
416 protected final Class<?> defineClass(byte[] b, int off, int len)
417 throws ClassFormatError
418 {
419 return defineClass(null, b, off, len, null);
420 }
421
422 /**
423 * Converts an array of bytes into an instance of class <tt>Class</tt>.
424 * Before the <tt>Class</tt> can be used it must be resolved.
425 *
426 * <p> This method assigns a default {@link java.security.ProtectionDomain
427 * <tt>ProtectionDomain</tt>} to the newly defined class. The
428 * <tt>ProtectionDomain</tt> is effectively granted the same set of
429 * permissions returned when {@link
430 * java.security.Policy#getPermissions(java.security.CodeSource)
431 * <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
432 * is invoked. The default domain is created on the first invocation of
433 * {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
434 * and re-used on subsequent invocations.
435 *
436 * <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
437 * the {@link #defineClass(String, byte[], int, int,
438 * java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
439 * <tt>ProtectionDomain</tt> as one of its arguments. </p>
440 *
441 * @param name
442 * The expected <a href="#name">binary name</a> of the class, or
443 * <tt>null</tt> if not known
444 *
445 * @param b
446 * The bytes that make up the class data. The bytes in positions
447 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
448 * of a valid class file as defined by the <a
449 * href="http://java.sun.com/docs/books/vmspec/">Java Virtual
450 * Machine Specification</a>.
451 *
452 * @param off
453 * The start offset in <tt>b</tt> of the class data
454 *
455 * @param len
456 * The length of the class data
457 *
458 * @return The <tt>Class</tt> object that was created from the specified
459 * class data.
460 *
461 * @throws ClassFormatError
462 * If the data did not contain a valid class
463 *
464 * @throws IndexOutOfBoundsException
465 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
466 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
467 *
468 * @throws SecurityException
469 * If an attempt is made to add this class to a package that
470 * contains classes that were signed by a different set of
471 * certificates than this class (which is unsigned), or if
472 * <tt>name</tt> begins with "<tt>java.</tt>".
473 *
474 * @see #loadClass(String, boolean)
475 * @see #resolveClass(Class)
476 * @see java.security.CodeSource
477 * @see java.security.SecureClassLoader
478 *
479 * @since 1.1
480 */
481 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
482 throws ClassFormatError
483 {
484 return defineClass(name, b, off, len, null);
485 }
486
487 /* Determine protection domain, and check that:
488 - not define java.* class,
489 - signer of this class matches signers for the rest of the classes in package.
490 */
491 private ProtectionDomain preDefineClass(String name,
492 ProtectionDomain protectionDomain)
493 {
494 if (!checkName(name))
495 throw new NoClassDefFoundError("IllegalName: " + name);
496
497 if ((name != null) && name.startsWith("java.")) {
498 throw new SecurityException("Prohibited package name: " +
499 name.substring(0, name.lastIndexOf('.')));
500 }
501 if (protectionDomain == null) {
502 protectionDomain = getDefaultDomain();
503 }
504
505 if (name != null)
506 checkCerts(name, protectionDomain.getCodeSource());
507
508 return protectionDomain;
509 }
510
511 private String defineClassSourceLocation(ProtectionDomain protectionDomain)
512 {
513 CodeSource cs = protectionDomain.getCodeSource();
514 String source = null;
515 if (cs != null && cs.getLocation() != null) {
516 source = cs.getLocation().toString();
517 }
518 return source;
519 }
520
521 private Class defineTransformedClass(String name, byte[] b, int off, int len,
522 ProtectionDomain protectionDomain,
523 ClassFormatError cfe, String source)
524 throws ClassFormatError
525 {
526 // Class format error - try to transform the bytecode and
527 // define the class again
528 //
529 ClassFileTransformer[] transformers = ClassFileTransformer.getTransformers();
530 Class c = null;
531
532 if (transformers != null) {
533 for (ClassFileTransformer transformer : transformers) {
534 try {
535 // Transform byte code using transformer
536 byte[] tb = transformer.transform(b, off, len);
537 c = defineClass1(name, tb, 0, tb.length,
538 protectionDomain, source);
539 break;
540 } catch (ClassFormatError cfe2) {
541 // If ClassFormatError occurs, try next transformer
542 }
543 }
544 }
545
546 // Rethrow original ClassFormatError if unable to transform
547 // bytecode to well-formed
548 //
549 if (c == null)
550 throw cfe;
551
552 return c;
553 }
554
555 private void postDefineClass(Class c, ProtectionDomain protectionDomain)
556 {
557 if (protectionDomain.getCodeSource() != null) {
558 Certificate certs[] =
559 protectionDomain.getCodeSource().getCertificates();
560 if (certs != null)
561 setSigners(c, certs);
562 }
563 }
564
565 /**
566 * Converts an array of bytes into an instance of class <tt>Class</tt>,
567 * with an optional <tt>ProtectionDomain</tt>. If the domain is
568 * <tt>null</tt>, then a default domain will be assigned to the class as
569 * specified in the documentation for {@link #defineClass(String, byte[],
570 * int, int)}. Before the class can be used it must be resolved.
571 *
572 * <p> The first class defined in a package determines the exact set of
573 * certificates that all subsequent classes defined in that package must
574 * contain. The set of certificates for a class is obtained from the
575 * {@link java.security.CodeSource <tt>CodeSource</tt>} within the
576 * <tt>ProtectionDomain</tt> of the class. Any classes added to that
577 * package must contain the same set of certificates or a
578 * <tt>SecurityException</tt> will be thrown. Note that if
579 * <tt>name</tt> is <tt>null</tt>, this check is not performed.
580 * You should always pass in the <a href="#name">binary name</a> of the
581 * class you are defining as well as the bytes. This ensures that the
582 * class you are defining is indeed the class you think it is.
583 *
584 * <p> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
585 * all classes in the "<tt>java.*</tt> packages can only be defined by the
586 * bootstrap class loader. If <tt>name</tt> is not <tt>null</tt>, it
587 * must be equal to the <a href="#name">binary name</a> of the class
588 * specified by the byte array "<tt>b</tt>", otherwise a {@link
589 * <tt>NoClassDefFoundError</tt>} will be thrown. </p>
590 *
591 * @param name
592 * The expected <a href="#name">binary name</a> of the class, or
593 * <tt>null</tt> if not known
594 *
595 * @param b
596 * The bytes that make up the class data. The bytes in positions
597 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
598 * of a valid class file as defined by the <a
599 * href="http://java.sun.com/docs/books/vmspec/">Java Virtual
600 * Machine Specification</a>.
601 *
602 * @param off
603 * The start offset in <tt>b</tt> of the class data
604 *
605 * @param len
606 * The length of the class data
607 *
608 * @param protectionDomain
609 * The ProtectionDomain of the class
610 *
611 * @return The <tt>Class</tt> object created from the data,
612 * and optional <tt>ProtectionDomain</tt>.
613 *
614 * @throws ClassFormatError
615 * If the data did not contain a valid class
616 *
617 * @throws NoClassDefFoundError
618 * If <tt>name</tt> is not equal to the <a href="#name">binary
619 * name</a> of the class specified by <tt>b</tt>
620 *
621 * @throws IndexOutOfBoundsException
622 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
623 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
624 *
625 * @throws SecurityException
626 * If an attempt is made to add this class to a package that
627 * contains classes that were signed by a different set of
628 * certificates than this class, or if <tt>name</tt> begins with
629 * "<tt>java.</tt>".
630 */
631 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
632 ProtectionDomain protectionDomain)
633 throws ClassFormatError
634 {
635 check();
636 protectionDomain = preDefineClass(name, protectionDomain);
637
638 Class c = null;
639 String source = defineClassSourceLocation(protectionDomain);
640
641 try {
642 c = defineClass1(name, b, off, len, protectionDomain, source);
643 } catch (ClassFormatError cfe) {
644 c = defineTransformedClass(name, b, off, len, protectionDomain, cfe, source);
645 }
646
647 postDefineClass(c, protectionDomain);
648 return c;
649 }
650
651 /**
652 * Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
653 * into an instance of class <tt>Class</tt>,
654 * with an optional <tt>ProtectionDomain</tt>. If the domain is
655 * <tt>null</tt>, then a default domain will be assigned to the class as
656 * specified in the documentation for {@link #defineClass(String, byte[],
657 * int, int)}. Before the class can be used it must be resolved.
658 *
659 * <p>The rules about the first class defined in a package determining the set of
660 * certificates for the package, and the restrictions on class names are identical
661 * to those specified in the documentation for {@link #defineClass(String, byte[],
662 * int, int, ProtectionDomain)}.
663 *
664 * <p> An invocation of this method of the form
665 * <i>cl</i><tt>.defineClass(</tt><i>name</i><tt>,</tt>
666 * <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
667 * result as the statements
668 *
669 * <blockquote><tt>
670 * ...<br>
671 * byte[] temp = new byte[</tt><i>bBuffer</i><tt>.{@link java.nio.ByteBuffer#remaining
672 * remaining}()];<br>
673 * </tt><i>bBuffer</i><tt>.{@link java.nio.ByteBuffer#get(byte[])
674 * get}(temp);<br>
675 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
676 * </tt><i>cl</i><tt>.defineClass}(</tt><i>name</i><tt>, temp, 0, temp.length, </tt><i>pd</i><tt>);<br>
677 * </tt></blockquote>
678 *
679 * @param name
680 * The expected <a href="#name">binary name</a. of the class, or
681 * <tt>null</tt> if not known
682 *
683 * @param b
684 * The bytes that make up the class data. The bytes from positions
685 * <tt>b.position()</tt> through <tt>b.position() + b.limit() -1 </tt>
686 * should have the format of a valid class file as defined by the <a
687 * href="http://java.sun.com/docs/books/vmspec/">Java Virtual
688 * Machine Specification</a>.
689 *
690 * @param protectionDomain
691 * The ProtectionDomain of the class, or <tt>null</tt>.
692 *
693 * @return The <tt>Class</tt> object created from the data,
694 * and optional <tt>ProtectionDomain</tt>.
695 *
696 * @throws ClassFormatError
697 * If the data did not contain a valid class.
698 *
699 * @throws NoClassDefFoundError
700 * If <tt>name</tt> is not equal to the <a href="#name">binary
701 * name</a> of the class specified by <tt>b</tt>
702 *
703 * @throws SecurityException
704 * If an attempt is made to add this class to a package that
705 * contains classes that were signed by a different set of
706 * certificates than this class, or if <tt>name</tt> begins with
707 * "<tt>java.</tt>".
708 *
709 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
710 *
711 * @since 1.5
712 */
713 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
714 ProtectionDomain protectionDomain)
715 throws ClassFormatError
716 {
717 check();
718
719 int len = b.remaining();
720
721 // Use byte[] if not a direct ByteBufer:
722 if (!b.isDirect()) {
723 if (b.hasArray()) {
724 return defineClass(name, b.array(),
725 b.position() + b.arrayOffset(), len,
726 protectionDomain);
727 } else {
728 // no array, or read-only array
729 byte[] tb = new byte[len];
730 b.get(tb); // get bytes out of byte buffer.
731 return defineClass(name, tb, 0, len, protectionDomain);
732 }
733 }
734
735 protectionDomain = preDefineClass(name, protectionDomain);
736
737 Class c = null;
738 String source = defineClassSourceLocation(protectionDomain);
739
740 try {
741 c = defineClass2(name, b, b.position(), len, protectionDomain, source);
742 } catch (ClassFormatError cfe) {
743 byte[] tb = new byte[len];
744 b.get(tb); // get bytes out of byte buffer.
745 c = defineTransformedClass(name, tb, 0, len, protectionDomain, cfe, source);
746 }
747
748 postDefineClass(c, protectionDomain);
749 return c;
750 }
751
752 private native Class defineClass0(String name, byte[] b, int off, int len,
753 ProtectionDomain pd);
754
755 private native Class defineClass1(String name, byte[] b, int off, int len,
756 ProtectionDomain pd, String source);
757
758 private native Class defineClass2(String name, java.nio.ByteBuffer b,
759 int off, int len, ProtectionDomain pd,
760 String source);
761
762 // true if the name is null or has the potential to be a valid binary name
763 private boolean checkName(String name) {
764 if ((name == null) || (name.length() == 0))
765 return true;
766 if ((name.indexOf('/') != -1)
767 || (!VM.allowArraySyntax() && (name.charAt(0) == '[')))
768 return false;
769 return true;
770 }
771
772 private synchronized void checkCerts(String name, CodeSource cs) {
773 int i = name.lastIndexOf('.');
774 String pname = (i == -1) ? "" : name.substring(0, i);
775 Certificate[] pcerts = package2certs.get(pname);
776 if (pcerts == null) {
777 // first class in this package gets to define which
778 // certificates must be the same for all other classes
779 // in this package
780 if (cs != null) {
781 pcerts = cs.getCertificates();
782 }
783 if (pcerts == null) {
784 if (nocerts == null)
785 nocerts = new Certificate[0];
786 pcerts = nocerts;
787 }
788 package2certs.put(pname, pcerts);
789 } else {
790 Certificate[] certs = null;
791 if (cs != null) {
792 certs = cs.getCertificates();
793 }
794
795 if (!compareCerts(pcerts, certs)) {
796 throw new SecurityException("class \""+ name +
797 "\"'s signer information does not match signer information of other classes in the same package");
798 }
799 }
800 }
801
802 /**
803 * check to make sure the certs for the new class (certs) are the same as
804 * the certs for the first class inserted in the package (pcerts)
805 */
806 private boolean compareCerts(Certificate[] pcerts,
807 Certificate[] certs)
808 {
809 // certs can be null, indicating no certs.
810 if ((certs == null) || (certs.length == 0)) {
811 return pcerts.length == 0;
812 }
813
814 // the length must be the same at this point
815 if (certs.length != pcerts.length)
816 return false;
817
818 // go through and make sure all the certs in one array
819 // are in the other and vice-versa.
820 boolean match;
821 for (int i = 0; i < certs.length; i++) {
822 match = false;
823 for (int j = 0; j < pcerts.length; j++) {
824 if (certs[i].equals(pcerts[j])) {
825 match = true;
826 break;
827 }
828 }
829 if (!match) return false;
830 }
831
832 // now do the same for pcerts
833 for (int i = 0; i < pcerts.length; i++) {
834 match = false;
835 for (int j = 0; j < certs.length; j++) {
836 if (pcerts[i].equals(certs[j])) {
837 match = true;
838 break;
839 }
840 }
841 if (!match) return false;
842 }
843
844 return true;
845 }
846
847 /**
848 * Links the specified class. This (misleadingly named) method may be
849 * used by a class loader to link a class. If the class <tt>c</tt> has
850 * already been linked, then this method simply returns. Otherwise, the
851 * class is linked as described in the "Execution" chapter of the <a
852 * href="http://java.sun.com/docs/books/jls/">Java Language
853 * Specification</a>.
854 * </p>
855 *
856 * @param c
857 * The class to link
858 *
859 * @throws NullPointerException
860 * If <tt>c</tt> is <tt>null</tt>.
861 *
862 * @see #defineClass(String, byte[], int, int)
863 */
864 protected final void resolveClass(Class<?> c) {
865 check();
866 resolveClass0(c);
867 }
868
869 private native void resolveClass0(Class c);
870
871 /**
872 * Finds a class with the specified <a href="#name">binary name</a>,
873 * loading it if necessary.
874 *
875 * <p> This method loads the class through the system class loader (see
876 * {@link #getSystemClassLoader()}). The <tt>Class</tt> object returned
877 * might have more than one <tt>ClassLoader</tt> associated with it.
878 * Subclasses of <tt>ClassLoader</tt> need not usually invoke this method,
879 * because most class loaders need to override just {@link
880 * #findClass(String)}. </p>
881 *
882 * @param name
883 * The <a href="#name">binary name</a> of the class
884 *
885 * @return The <tt>Class</tt> object for the specified <tt>name</tt>
886 *
887 * @throws ClassNotFoundException
888 * If the class could not be found
889 *
890 * @see #ClassLoader(ClassLoader)
891 * @see #getParent()
892 */
893 protected final Class<?> findSystemClass(String name)
894 throws ClassNotFoundException
895 {
896 check();
897 ClassLoader system = getSystemClassLoader();
898 if (system == null) {
899 if (!checkName(name))
900 throw new ClassNotFoundException(name);
901 return findBootstrapClass(name);
902 }
903 return system.loadClass(name);
904 }
905
906 private Class findBootstrapClass0(String name)
907 throws ClassNotFoundException
908 {
909 check();
910 if (!checkName(name))
911 throw new ClassNotFoundException(name);
912 return findBootstrapClass(name);
913 }
914
915 private native Class findBootstrapClass(String name)
916 throws ClassNotFoundException;
917
918 // Check to make sure the class loader has been initialized.
919 private void check() {
920 if (!initialized) {
921 throw new SecurityException("ClassLoader object not initialized");
922 }
923 }
924
925 /**
926 * Returns the class with the given <a href="#name">binary name</a> if this
927 * loader has been recorded by the Java virtual machine as an initiating
928 * loader of a class with that <a href="#name">binary name</a>. Otherwise
929 * <tt>null</tt> is returned. </p>
930 *
931 * @param name
932 * The <a href="#name">binary name</a> of the class
933 *
934 * @return The <tt>Class</tt> object, or <tt>null</tt> if the class has
935 * not been loaded
936 *
937 * @since 1.1
938 */
939 protected final Class<?> findLoadedClass(String name) {
940 check();
941 if (!checkName(name))
942 return null;
943 return findLoadedClass0(name);
944 }
945
946 private native final Class findLoadedClass0(String name);
947
948 /**
949 * Sets the signers of a class. This should be invoked after defining a
950 * class. </p>
951 *
952 * @param c
953 * The <tt>Class</tt> object
954 *
955 * @param signers
956 * The signers for the class
957 *
958 * @since 1.1
959 */
960 protected final void setSigners(Class<?> c, Object[] signers) {
961 check();
962 c.setSigners(signers);
963 }
964
965
966 // -- Resource --
967
968 /**
969 * Finds the resource with the given name. A resource is some data
970 * (images, audio, text, etc) that can be accessed by class code in a way
971 * that is independent of the location of the code.
972 *
973 * <p> The name of a resource is a '<tt>/</tt>'-separated path name that
974 * identifies the resource.
975 *
976 * <p> This method will first search the parent class loader for the
977 * resource; if the parent is <tt>null</tt> the path of the class loader
978 * built-in to the virtual machine is searched. That failing, this method
979 * will invoke {@link #findResource(String)} to find the resource. </p>
980 *
981 * @param name
982 * The resource name
983 *
984 * @return A <tt>URL</tt> object for reading the resource, or
985 * <tt>null</tt> if the resource could not be found or the invoker
986 * doesn't have adequate privileges to get the resource.
987 *
988 * @since 1.1
989 */
990 public URL getResource(String name) {
991 URL url;
992 if (parent != null) {
993 url = parent.getResource(name);
994 } else {
995 url = getBootstrapResource(name);
996 }
997 if (url == null) {
998 url = findResource(name);
999 }
1000 return url;
1001 }
1002
1003 /**
1004 * Finds all the resources with the given name. A resource is some data
1005 * (images, audio, text, etc) that can be accessed by class code in a way
1006 * that is independent of the location of the code.
1007 *
1008 * <p>The name of a resource is a <tt>/</tt>-separated path name that
1009 * identifies the resource.
1010 *
1011 * <p> The search order is described in the documentation for {@link
1012 * #getResource(String)}. </p>
1013 *
1014 * @param name
1015 * The resource name
1016 *
1017 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1018 * the resource. If no resources could be found, the enumeration
1019 * will be empty. Resources that the class loader doesn't have
1020 * access to will not be in the enumeration.
1021 *
1022 * @throws IOException
1023 * If I/O errors occur
1024 *
1025 * @see #findResources(String)
1026 *
1027 * @since 1.2
1028 */
1029 public Enumeration<URL> getResources(String name) throws IOException {
1030 Enumeration[] tmp = new Enumeration[2];
1031 if (parent != null) {
1032 tmp[0] = parent.getResources(name);
1033 } else {
1034 tmp[0] = getBootstrapResources(name);
1035 }
1036 tmp[1] = findResources(name);
1037
1038 return new CompoundEnumeration<URL>(tmp);
1039 }
1040
1041 /**
1042 * Finds the resource with the given name. Class loader implementations
1043 * should override this method to specify where to find resources. </p>
1044 *
1045 * @param name
1046 * The resource name
1047 *
1048 * @return A <tt>URL</tt> object for reading the resource, or
1049 * <tt>null</tt> if the resource could not be found
1050 *
1051 * @since 1.2
1052 */
1053 protected URL findResource(String name) {
1054 return null;
1055 }
1056
1057 /**
1058 * Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
1059 * representing all the resources with the given name. Class loader
1060 * implementations should override this method to specify where to load
1061 * resources from. </p>
1062 *
1063 * @param name
1064 * The resource name
1065 *
1066 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1067 * the resources
1068 *
1069 * @throws IOException
1070 * If I/O errors occur
1071 *
1072 * @since 1.2
1073 */
1074 protected Enumeration<URL> findResources(String name) throws IOException {
1075 return java.util.Collections.emptyEnumeration();
1076 }
1077
1078 /**
1079 * Find a resource of the specified name from the search path used to load
1080 * classes. This method locates the resource through the system class
1081 * loader (see {@link #getSystemClassLoader()}). </p>
1082 *
1083 * @param name
1084 * The resource name
1085 *
1086 * @return A {@link java.net.URL <tt>URL</tt>} object for reading the
1087 * resource, or <tt>null</tt> if the resource could not be found
1088 *
1089 * @since 1.1
1090 */
1091 public static URL getSystemResource(String name) {
1092 ClassLoader system = getSystemClassLoader();
1093 if (system == null) {
1094 return getBootstrapResource(name);
1095 }
1096 return system.getResource(name);
1097 }
1098
1099 /**
1100 * Finds all resources of the specified name from the search path used to
1101 * load classes. The resources thus found are returned as an
1102 * {@link java.util.Enumeration <tt>Enumeration</tt>} of {@link
1103 * java.net.URL <tt>URL</tt>} objects.
1104 *
1105 * <p> The search order is described in the documentation for {@link
1106 * #getSystemResource(String)}. </p>
1107 *
1108 * @param name
1109 * The resource name
1110 *
1111 * @return An enumeration of resource {@link java.net.URL <tt>URL</tt>}
1112 * objects
1113 *
1114 * @throws IOException
1115 * If I/O errors occur
1116
1117 * @since 1.2
1118 */
1119 public static Enumeration<URL> getSystemResources(String name)
1120 throws IOException
1121 {
1122 ClassLoader system = getSystemClassLoader();
1123 if (system == null) {
1124 return getBootstrapResources(name);
1125 }
1126 return system.getResources(name);
1127 }
1128
1129 /**
1130 * Find resources from the VM's built-in classloader.
1131 */
1132 private static URL getBootstrapResource(String name) {
1133 URLClassPath ucp = getBootstrapClassPath();
1134 Resource res = ucp.getResource(name);
1135 return res != null ? res.getURL() : null;
1136 }
1137
1138 /**
1139 * Find resources from the VM's built-in classloader.
1140 */
1141 private static Enumeration<URL> getBootstrapResources(String name)
1142 throws IOException
1143 {
1144 final Enumeration<Resource> e = getBootstrapClassPath().getResources(name);
1145 return new Enumeration<URL> () {
1146 public URL nextElement() {
1147 return e.nextElement().getURL();
1148 }
1149 public boolean hasMoreElements() {
1150 return e.hasMoreElements();
1151 }
1152 };
1153 }
1154
1155 // Returns the URLClassPath that is used for finding system resources.
1156 static URLClassPath getBootstrapClassPath() {
1157 if (bootstrapClassPath == null) {
1158 bootstrapClassPath = sun.misc.Launcher.getBootstrapClassPath();
1159 }
1160 return bootstrapClassPath;
1161 }
1162
1163 private static URLClassPath bootstrapClassPath;
1164
1165 /**
1166 * Returns an input stream for reading the specified resource.
1167 *
1168 * <p> The search order is described in the documentation for {@link
1169 * #getResource(String)}. </p>
1170 *
1171 * @param name
1172 * The resource name
1173 *
1174 * @return An input stream for reading the resource, or <tt>null</tt>
1175 * if the resource could not be found
1176 *
1177 * @since 1.1
1178 */
1179 public InputStream getResourceAsStream(String name) {
1180 URL url = getResource(name);
1181 try {
1182 return url != null ? url.openStream() : null;
1183 } catch (IOException e) {
1184 return null;
1185 }
1186 }
1187
1188 /**
1189 * Open for reading, a resource of the specified name from the search path
1190 * used to load classes. This method locates the resource through the
1191 * system class loader (see {@link #getSystemClassLoader()}). </p>
1192 *
1193 * @param name
1194 * The resource name
1195 *
1196 * @return An input stream for reading the resource, or <tt>null</tt>
1197 * if the resource could not be found
1198 *
1199 * @since 1.1
1200 */
1201 public static InputStream getSystemResourceAsStream(String name) {
1202 URL url = getSystemResource(name);
1203 try {
1204 return url != null ? url.openStream() : null;
1205 } catch (IOException e) {
1206 return null;
1207 }
1208 }
1209
1210
1211 // -- Hierarchy --
1212
1213 /**
1214 * Returns the parent class loader for delegation. Some implementations may
1215 * use <tt>null</tt> to represent the bootstrap class loader. This method
1216 * will return <tt>null</tt> in such implementations if this class loader's
1217 * parent is the bootstrap class loader.
1218 *
1219 * <p> If a security manager is present, and the invoker's class loader is
1220 * not <tt>null</tt> and is not an ancestor of this class loader, then this
1221 * method invokes the security manager's {@link
1222 * SecurityManager#checkPermission(java.security.Permission)
1223 * <tt>checkPermission</tt>} method with a {@link
1224 * RuntimePermission#RuntimePermission(String)
1225 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1226 * access to the parent class loader is permitted. If not, a
1227 * <tt>SecurityException</tt> will be thrown. </p>
1228 *
1229 * @return The parent <tt>ClassLoader</tt>
1230 *
1231 * @throws SecurityException
1232 * If a security manager exists and its <tt>checkPermission</tt>
1233 * method doesn't allow access to this class loader's parent class
1234 * loader.
1235 *
1236 * @since 1.2
1237 */
1238 public final ClassLoader getParent() {
1239 if (parent == null)
1240 return null;
1241 SecurityManager sm = System.getSecurityManager();
1242 if (sm != null) {
1243 ClassLoader ccl = getCallerClassLoader();
1244 if (ccl != null && !isAncestor(ccl)) {
1245 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1246 }
1247 }
1248 return parent;
1249 }
1250
1251 /**
1252 * Returns the system class loader for delegation. This is the default
1253 * delegation parent for new <tt>ClassLoader</tt> instances, and is
1254 * typically the class loader used to start the application.
1255 *
1256 * <p> This method is first invoked early in the runtime's startup
1257 * sequence, at which point it creates the system class loader and sets it
1258 * as the context class loader of the invoking <tt>Thread</tt>.
1259 *
1260 * <p> The default system class loader is an implementation-dependent
1261 * instance of this class.
1262 *
1263 * <p> If the system property "<tt>java.system.class.loader</tt>" is defined
1264 * when this method is first invoked then the value of that property is
1265 * taken to be the name of a class that will be returned as the system
1266 * class loader. The class is loaded using the default system class loader
1267 * and must define a public constructor that takes a single parameter of
1268 * type <tt>ClassLoader</tt> which is used as the delegation parent. An
1269 * instance is then created using this constructor with the default system
1270 * class loader as the parameter. The resulting class loader is defined
1271 * to be the system class loader.
1272 *
1273 * <p> If a security manager is present, and the invoker's class loader is
1274 * not <tt>null</tt> and the invoker's class loader is not the same as or
1275 * an ancestor of the system class loader, then this method invokes the
1276 * security manager's {@link
1277 * SecurityManager#checkPermission(java.security.Permission)
1278 * <tt>checkPermission</tt>} method with a {@link
1279 * RuntimePermission#RuntimePermission(String)
1280 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1281 * access to the system class loader. If not, a
1282 * <tt>SecurityException</tt> will be thrown. </p>
1283 *
1284 * @return The system <tt>ClassLoader</tt> for delegation, or
1285 * <tt>null</tt> if none
1286 *
1287 * @throws SecurityException
1288 * If a security manager exists and its <tt>checkPermission</tt>
1289 * method doesn't allow access to the system class loader.
1290 *
1291 * @throws IllegalStateException
1292 * If invoked recursively during the construction of the class
1293 * loader specified by the "<tt>java.system.class.loader</tt>"
1294 * property.
1295 *
1296 * @throws Error
1297 * If the system property "<tt>java.system.class.loader</tt>"
1298 * is defined but the named class could not be loaded, the
1299 * provider class does not define the required constructor, or an
1300 * exception is thrown by that constructor when it is invoked. The
1301 * underlying cause of the error can be retrieved via the
1302 * {@link Throwable#getCause()} method.
1303 *
1304 * @revised 1.4
1305 */
1306 public static ClassLoader getSystemClassLoader() {
1307 initSystemClassLoader();
1308 if (scl == null) {
1309 return null;
1310 }
1311 SecurityManager sm = System.getSecurityManager();
1312 if (sm != null) {
1313 ClassLoader ccl = getCallerClassLoader();
1314 if (ccl != null && ccl != scl && !scl.isAncestor(ccl)) {
1315 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1316 }
1317 }
1318 return scl;
1319 }
1320
1321 private static synchronized void initSystemClassLoader() {
1322 if (!sclSet) {
1323 if (scl != null)
1324 throw new IllegalStateException("recursive invocation");
1325 sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
1326 if (l != null) {
1327 Throwable oops = null;
1328 scl = l.getClassLoader();
1329 try {
1330 scl = AccessController.doPrivileged(
1331 new SystemClassLoaderAction(scl));
1332 } catch (PrivilegedActionException pae) {
1333 oops = pae.getCause();
1334 if (oops instanceof InvocationTargetException) {
1335 oops = oops.getCause();
1336 }
1337 }
1338 if (oops != null) {
1339 if (oops instanceof Error) {
1340 throw (Error) oops;
1341 } else {
1342 // wrap the exception
1343 throw new Error(oops);
1344 }
1345 }
1346 }
1347 sclSet = true;
1348 }
1349 }
1350
1351 // Returns true if the specified class loader can be found in this class
1352 // loader's delegation chain.
1353 boolean isAncestor(ClassLoader cl) {
1354 ClassLoader acl = this;
1355 do {
1356 acl = acl.parent;
1357 if (cl == acl) {
1358 return true;
1359 }
1360 } while (acl != null);
1361 return false;
1362 }
1363
1364 // Returns the invoker's class loader, or null if none.
1365 // NOTE: This must always be invoked when there is exactly one intervening
1366 // frame from the core libraries on the stack between this method's
1367 // invocation and the desired invoker.
1368 static ClassLoader getCallerClassLoader() {
1369 // NOTE use of more generic Reflection.getCallerClass()
1370 Class caller = Reflection.getCallerClass(3);
1371 // This can be null if the VM is requesting it
1372 if (caller == null) {
1373 return null;
1374 }
1375 // Circumvent security check since this is package-private
1376 return caller.getClassLoader0();
1377 }
1378
1379 // The class loader for the system
1380 private static ClassLoader scl;
1381
1382 // Set to true once the system class loader has been set
1383 private static boolean sclSet;
1384
1385
1386 // -- Package --
1387
1388 /**
1389 * Defines a package by name in this <tt>ClassLoader</tt>. This allows
1390 * class loaders to define the packages for their classes. Packages must
1391 * be created before the class is defined, and package names must be
1392 * unique within a class loader and cannot be redefined or changed once
1393 * created. </p>
1394 *
1395 * @param name
1396 * The package name
1397 *
1398 * @param specTitle
1399 * The specification title
1400 *
1401 * @param specVersion
1402 * The specification version
1403 *
1404 * @param specVendor
1405 * The specification vendor
1406 *
1407 * @param implTitle
1408 * The implementation title
1409 *
1410 * @param implVersion
1411 * The implementation version
1412 *
1413 * @param implVendor
1414 * The implementation vendor
1415 *
1416 * @param sealBase
1417 * If not <tt>null</tt>, then this package is sealed with
1418 * respect to the given code source {@link java.net.URL
1419 * <tt>URL</tt>} object. Otherwise, the package is not sealed.
1420 *
1421 * @return The newly defined <tt>Package</tt> object
1422 *
1423 * @throws IllegalArgumentException
1424 * If package name duplicates an existing package either in this
1425 * class loader or one of its ancestors
1426 *
1427 * @since 1.2
1428 */
1429 protected Package definePackage(String name, String specTitle,
1430 String specVersion, String specVendor,
1431 String implTitle, String implVersion,
1432 String implVendor, URL sealBase)
1433 throws IllegalArgumentException
1434 {
1435 synchronized (packages) {
1436 Package pkg = getPackage(name);
1437 if (pkg != null) {
1438 throw new IllegalArgumentException(name);
1439 }
1440 pkg = new Package(name, specTitle, specVersion, specVendor,
1441 implTitle, implVersion, implVendor,
1442 sealBase, this);
1443 packages.put(name, pkg);
1444 return pkg;
1445 }
1446 }
1447
1448 /**
1449 * Returns a <tt>Package</tt> that has been defined by this class loader
1450 * or any of its ancestors. </p>
1451 *
1452 * @param name
1453 * The package name
1454 *
1455 * @return The <tt>Package</tt> corresponding to the given name, or
1456 * <tt>null</tt> if not found
1457 *
1458 * @since 1.2
1459 */
1460 protected Package getPackage(String name) {
1461 synchronized (packages) {
1462 Package pkg = packages.get(name);
1463 if (pkg == null) {
1464 if (parent != null) {
1465 pkg = parent.getPackage(name);
1466 } else {
1467 pkg = Package.getSystemPackage(name);
1468 }
1469 if (pkg != null) {
1470 packages.put(name, pkg);
1471 }
1472 }
1473 return pkg;
1474 }
1475 }
1476
1477 /**
1478 * Returns all of the <tt>Packages</tt> defined by this class loader and
1479 * its ancestors. </p>
1480 *
1481 * @return The array of <tt>Package</tt> objects defined by this
1482 * <tt>ClassLoader</tt>
1483 *
1484 * @since 1.2
1485 */
1486 protected Package[] getPackages() {
1487 Map<String, Package> map;
1488 synchronized (packages) {
1489 map = new HashMap<String, Package>(packages);
1490 }
1491 Package[] pkgs;
1492 if (parent != null) {
1493 pkgs = parent.getPackages();
1494 } else {
1495 pkgs = Package.getSystemPackages();
1496 }
1497 if (pkgs != null) {
1498 for (int i = 0; i < pkgs.length; i++) {
1499 String pkgName = pkgs[i].getName();
1500 if (map.get(pkgName) == null) {
1501 map.put(pkgName, pkgs[i]);
1502 }
1503 }
1504 }
1505 return map.values().toArray(new Package[map.size()]);
1506 }
1507
1508
1509 // -- Native library access --
1510
1511 /**
1512 * Returns the absolute path name of a native library. The VM invokes this
1513 * method to locate the native libraries that belong to classes loaded with
1514 * this class loader. If this method returns <tt>null</tt>, the VM
1515 * searches the library along the path specified as the
1516 * "<tt>java.library.path</tt>" property. </p>
1517 *
1518 * @param libname
1519 * The library name
1520 *
1521 * @return The absolute path of the native library
1522 *
1523 * @see System#loadLibrary(String)
1524 * @see System#mapLibraryName(String)
1525 *
1526 * @since 1.2
1527 */
1528 protected String findLibrary(String libname) {
1529 return null;
1530 }
1531
1532 /**
1533 * The inner class NativeLibrary denotes a loaded native library instance.
1534 * Every classloader contains a vector of loaded native libraries in the
1535 * private field <tt>nativeLibraries</tt>. The native libraries loaded
1536 * into the system are entered into the <tt>systemNativeLibraries</tt>
1537 * vector.
1538 *
1539 * <p> Every native library requires a particular version of JNI. This is
1540 * denoted by the private <tt>jniVersion</tt> field. This field is set by
1541 * the VM when it loads the library, and used by the VM to pass the correct
1542 * version of JNI to the native methods. </p>
1543 *
1544 * @see ClassLoader
1545 * @since 1.2
1546 */
1547 static class NativeLibrary {
1548 // opaque handle to native library, used in native code.
1549 long handle;
1550 // the version of JNI environment the native library requires.
1551 private int jniVersion;
1552 // the class from which the library is loaded, also indicates
1553 // the loader this native library belongs.
1554 private Class fromClass;
1555 // the canonicalized name of the native library.
1556 String name;
1557
1558 native void load(String name);
1559 native long find(String name);
1560 native void unload();
1561
1562 public NativeLibrary(Class fromClass, String name) {
1563 this.name = name;
1564 this.fromClass = fromClass;
1565 }
1566
1567 protected void finalize() {
1568 synchronized (loadedLibraryNames) {
1569 if (fromClass.getClassLoader() != null && handle != 0) {
1570 /* remove the native library name */
1571 int size = loadedLibraryNames.size();
1572 for (int i = 0; i < size; i++) {
1573 if (name.equals(loadedLibraryNames.elementAt(i))) {
1574 loadedLibraryNames.removeElementAt(i);
1575 break;
1576 }
1577 }
1578 /* unload the library. */
1579 ClassLoader.nativeLibraryContext.push(this);
1580 try {
1581 unload();
1582 } finally {
1583 ClassLoader.nativeLibraryContext.pop();
1584 }
1585 }
1586 }
1587 }
1588 // Invoked in the VM to determine the context class in
1589 // JNI_Load/JNI_Unload
1590 static Class getFromClass() {
1591 return ClassLoader.nativeLibraryContext.peek().fromClass;
1592 }
1593 }
1594
1595 // The "default" domain. Set as the default ProtectionDomain on newly
1596 // created classes.
1597 private ProtectionDomain defaultDomain = null;
1598
1599 // Returns (and initializes) the default domain.
1600 private synchronized ProtectionDomain getDefaultDomain() {
1601 if (defaultDomain == null) {
1602 CodeSource cs = new CodeSource(null, (Certificate[]) null);
1603 defaultDomain = new ProtectionDomain(cs, null, this, null);
1604 }
1605 return defaultDomain;
1606 }
1607
1608 // All native library names we've loaded.
1609 private static Vector<String> loadedLibraryNames
1610 = new Vector<String>();
1611
1612 // Native libraries belonging to system classes.
1613 private static Vector<NativeLibrary> systemNativeLibraries
1614 = new Vector<NativeLibrary>();
1615
1616 // Native libraries associated with the class loader.
1617 private Vector<NativeLibrary> nativeLibraries
1618 = new Vector<NativeLibrary>();
1619
1620 // native libraries being loaded/unloaded.
1621 private static Stack<NativeLibrary> nativeLibraryContext
1622 = new Stack<NativeLibrary>();
1623
1624 // The paths searched for libraries
1625 static private String usr_paths[];
1626 static private String sys_paths[];
1627
1628 private static String[] initializePath(String propname) {
1629 String ldpath = System.getProperty(propname, "");
1630 String ps = File.pathSeparator;
1631 int ldlen = ldpath.length();
1632 int i, j, n;
1633 // Count the separators in the path
1634 i = ldpath.indexOf(ps);
1635 n = 0;
1636 while (i >= 0) {
1637 n++;
1638 i = ldpath.indexOf(ps, i + 1);
1639 }
1640
1641 // allocate the array of paths - n :'s = n + 1 path elements
1642 String[] paths = new String[n + 1];
1643
1644 // Fill the array with paths from the ldpath
1645 n = i = 0;
1646 j = ldpath.indexOf(ps);
1647 while (j >= 0) {
1648 if (j - i > 0) {
1649 paths[n++] = ldpath.substring(i, j);
1650 } else if (j - i == 0) {
1651 paths[n++] = ".";
1652 }
1653 i = j + 1;
1654 j = ldpath.indexOf(ps, i);
1655 }
1656 paths[n] = ldpath.substring(i, ldlen);
1657 return paths;
1658 }
1659
1660 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
1661 static void loadLibrary(Class fromClass, String name,
1662 boolean isAbsolute) {
1663 ClassLoader loader =
1664 (fromClass == null) ? null : fromClass.getClassLoader();
1665 if (sys_paths == null) {
1666 usr_paths = initializePath("java.library.path");
1667 sys_paths = initializePath("sun.boot.library.path");
1668 }
1669 if (isAbsolute) {
1670 if (loadLibrary0(fromClass, new File(name))) {
1671 return;
1672 }
1673 throw new UnsatisfiedLinkError("Can't load library: " + name);
1674 }
1675 if (loader != null) {
1676 String libfilename = loader.findLibrary(name);
1677 if (libfilename != null) {
1678 File libfile = new File(libfilename);
1679 if (!libfile.isAbsolute()) {
1680 throw new UnsatisfiedLinkError(
1681 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
1682 }
1683 if (loadLibrary0(fromClass, libfile)) {
1684 return;
1685 }
1686 throw new UnsatisfiedLinkError("Can't load " + libfilename);
1687 }
1688 }
1689 for (int i = 0 ; i < sys_paths.length ; i++) {
1690 File libfile = new File(sys_paths[i], System.mapLibraryName(name));
1691 if (loadLibrary0(fromClass, libfile)) {
1692 return;
1693 }
1694 }
1695 if (loader != null) {
1696 for (int i = 0 ; i < usr_paths.length ; i++) {
1697 File libfile = new File(usr_paths[i],
1698 System.mapLibraryName(name));
1699 if (loadLibrary0(fromClass, libfile)) {
1700 return;
1701 }
1702 }
1703 }
1704 // Oops, it failed
1705 throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
1706 }
1707
1708 private static boolean loadLibrary0(Class fromClass, final File file) {
1709 boolean exists = AccessController.doPrivileged(
1710 new PrivilegedAction<Object>() {
1711 public Object run() {
1712 return file.exists() ? Boolean.TRUE : null;
1713 }})
1714 != null;
1715 if (!exists) {
1716 return false;
1717 }
1718 String name;
1719 try {
1720 name = file.getCanonicalPath();
1721 } catch (IOException e) {
1722 return false;
1723 }
1724 ClassLoader loader =
1725 (fromClass == null) ? null : fromClass.getClassLoader();
1726 Vector<NativeLibrary> libs =
1727 loader != null ? loader.nativeLibraries : systemNativeLibraries;
1728 synchronized (libs) {
1729 int size = libs.size();
1730 for (int i = 0; i < size; i++) {
1731 NativeLibrary lib = libs.elementAt(i);
1732 if (name.equals(lib.name)) {
1733 return true;
1734 }
1735 }
1736
1737 synchronized (loadedLibraryNames) {
1738 if (loadedLibraryNames.contains(name)) {
1739 throw new UnsatisfiedLinkError
1740 ("Native Library " +
1741 name +
1742 " already loaded in another classloader");
1743 }
1744 /* If the library is being loaded (must be by the same thread,
1745 * because Runtime.load and Runtime.loadLibrary are
1746 * synchronous). The reason is can occur is that the JNI_OnLoad
1747 * function can cause another loadLibrary invocation.
1748 *
1749 * Thus we can use a static stack to hold the list of libraries
1750 * we are loading.
1751 *
1752 * If there is a pending load operation for the library, we
1753 * immediately return success; otherwise, we raise
1754 * UnsatisfiedLinkError.
1755 */
1756 int n = nativeLibraryContext.size();
1757 for (int i = 0; i < n; i++) {
1758 NativeLibrary lib = nativeLibraryContext.elementAt(i);
1759 if (name.equals(lib.name)) {
1760 if (loader == lib.fromClass.getClassLoader()) {
1761 return true;
1762 } else {
1763 throw new UnsatisfiedLinkError
1764 ("Native Library " +
1765 name +
1766 " is being loaded in another classloader");
1767 }
1768 }
1769 }
1770 NativeLibrary lib = new NativeLibrary(fromClass, name);
1771 nativeLibraryContext.push(lib);
1772 try {
1773 lib.load(name);
1774 } finally {
1775 nativeLibraryContext.pop();
1776 }
1777 if (lib.handle != 0) {
1778 loadedLibraryNames.addElement(name);
1779 libs.addElement(lib);
1780 return true;
1781 }
1782 return false;
1783 }
1784 }
1785 }
1786
1787 // Invoked in the VM class linking code.
1788 static long findNative(ClassLoader loader, String name) {
1789 Vector<NativeLibrary> libs =
1790 loader != null ? loader.nativeLibraries : systemNativeLibraries;
1791 synchronized (libs) {
1792 int size = libs.size();
1793 for (int i = 0; i < size; i++) {
1794 NativeLibrary lib = libs.elementAt(i);
1795 long entry = lib.find(name);
1796 if (entry != 0)
1797 return entry;
1798 }
1799 }
1800 return 0;
1801 }
1802
1803
1804 // -- Assertion management --
1805
1806 // The default toggle for assertion checking.
1807 private boolean defaultAssertionStatus = false;
1808
1809 // Maps String packageName to Boolean package default assertion status Note
1810 // that the default package is placed under a null map key. If this field
1811 // is null then we are delegating assertion status queries to the VM, i.e.,
1812 // none of this ClassLoader's assertion status modification methods have
1813 // been invoked.
1814 private Map<String, Boolean> packageAssertionStatus = null;
1815
1816 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
1817 // field is null then we are delegating assertion status queries to the VM,
1818 // i.e., none of this ClassLoader's assertion status modification methods
1819 // have been invoked.
1820 Map<String, Boolean> classAssertionStatus = null;
1821
1822 /**
1823 * Sets the default assertion status for this class loader. This setting
1824 * determines whether classes loaded by this class loader and initialized
1825 * in the future will have assertions enabled or disabled by default.
1826 * This setting may be overridden on a per-package or per-class basis by
1827 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
1828 * #setClassAssertionStatus(String, boolean)}. </p>
1829 *
1830 * @param enabled
1831 * <tt>true</tt> if classes loaded by this class loader will
1832 * henceforth have assertions enabled by default, <tt>false</tt>
1833 * if they will have assertions disabled by default.
1834 *
1835 * @since 1.4
1836 */
1837 public synchronized void setDefaultAssertionStatus(boolean enabled) {
1838 if (classAssertionStatus == null)
1839 initializeJavaAssertionMaps();
1840
1841 defaultAssertionStatus = enabled;
1842 }
1843
1844 /**
1845 * Sets the package default assertion status for the named package. The
1846 * package default assertion status determines the assertion status for
1847 * classes initialized in the future that belong to the named package or
1848 * any of its "subpackages".
1849 *
1850 * <p> A subpackage of a package named p is any package whose name begins
1851 * with "<tt>p.</tt>". For example, <tt>javax.swing.text</tt> is a
1852 * subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt> and
1853 * <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
1854 *
1855 * <p> In the event that multiple package defaults apply to a given class,
1856 * the package default pertaining to the most specific package takes
1857 * precedence over the others. For example, if <tt>javax.lang</tt> and
1858 * <tt>javax.lang.reflect</tt> both have package defaults associated with
1859 * them, the latter package default applies to classes in
1860 * <tt>javax.lang.reflect</tt>.
1861 *
1862 * <p> Package defaults take precedence over the class loader's default
1863 * assertion status, and may be overridden on a per-class basis by invoking
1864 * {@link #setClassAssertionStatus(String, boolean)}. </p>
1865 *
1866 * @param packageName
1867 * The name of the package whose package default assertion status
1868 * is to be set. A <tt>null</tt> value indicates the unnamed
1869 * package that is "current"
1870 * (<a href="http://java.sun.com/docs/books/jls/">Java Language
1871 * Specification</a>, section 7.4.2).
1872 *
1873 * @param enabled
1874 * <tt>true</tt> if classes loaded by this classloader and
1875 * belonging to the named package or any of its subpackages will
1876 * have assertions enabled by default, <tt>false</tt> if they will
1877 * have assertions disabled by default.
1878 *
1879 * @since 1.4
1880 */
1881 public synchronized void setPackageAssertionStatus(String packageName,
1882 boolean enabled)
1883 {
1884 if (packageAssertionStatus == null)
1885 initializeJavaAssertionMaps();
1886
1887 packageAssertionStatus.put(packageName, enabled);
1888 }
1889
1890 /**
1891 * Sets the desired assertion status for the named top-level class in this
1892 * class loader and any nested classes contained therein. This setting
1893 * takes precedence over the class loader's default assertion status, and
1894 * over any applicable per-package default. This method has no effect if
1895 * the named class has already been initialized. (Once a class is
1896 * initialized, its assertion status cannot change.)
1897 *
1898 * <p> If the named class is not a top-level class, this invocation will
1899 * have no effect on the actual assertion status of any class. </p>
1900 *
1901 * @param className
1902 * The fully qualified class name of the top-level class whose
1903 * assertion status is to be set.
1904 *
1905 * @param enabled
1906 * <tt>true</tt> if the named class is to have assertions
1907 * enabled when (and if) it is initialized, <tt>false</tt> if the
1908 * class is to have assertions disabled.
1909 *
1910 * @since 1.4
1911 */
1912 public synchronized void setClassAssertionStatus(String className,
1913 boolean enabled)
1914 {
1915 if (classAssertionStatus == null)
1916 initializeJavaAssertionMaps();
1917
1918 classAssertionStatus.put(className, enabled);
1919 }
1920
1921 /**
1922 * Sets the default assertion status for this class loader to
1923 * <tt>false</tt> and discards any package defaults or class assertion
1924 * status settings associated with the class loader. This method is
1925 * provided so that class loaders can be made to ignore any command line or
1926 * persistent assertion status settings and "start with a clean slate."
1927 * </p>
1928 *
1929 * @since 1.4
1930 */
1931 public synchronized void clearAssertionStatus() {
1932 /*
1933 * Whether or not "Java assertion maps" are initialized, set
1934 * them to empty maps, effectively ignoring any present settings.
1935 */
1936 classAssertionStatus = new HashMap<String, Boolean>();
1937 packageAssertionStatus = new HashMap<String, Boolean>();
1938
1939 defaultAssertionStatus = false;
1940 }
1941
1942 /**
1943 * Returns the assertion status that would be assigned to the specified
1944 * class if it were to be initialized at the time this method is invoked.
1945 * If the named class has had its assertion status set, the most recent
1946 * setting will be returned; otherwise, if any package default assertion
1947 * status pertains to this class, the most recent setting for the most
1948 * specific pertinent package default assertion status is returned;
1949 * otherwise, this class loader's default assertion status is returned.
1950 * </p>
1951 *
1952 * @param className
1953 * The fully qualified class name of the class whose desired
1954 * assertion status is being queried.
1955 *
1956 * @return The desired assertion status of the specified class.
1957 *
1958 * @see #setClassAssertionStatus(String, boolean)
1959 * @see #setPackageAssertionStatus(String, boolean)
1960 * @see #setDefaultAssertionStatus(boolean)
1961 *
1962 * @since 1.4
1963 */
1964 synchronized boolean desiredAssertionStatus(String className) {
1965 Boolean result;
1966
1967 // assert classAssertionStatus != null;
1968 // assert packageAssertionStatus != null;
1969
1970 // Check for a class entry
1971 result = classAssertionStatus.get(className);
1972 if (result != null)
1973 return result.booleanValue();
1974
1975 // Check for most specific package entry
1976 int dotIndex = className.lastIndexOf(".");
1977 if (dotIndex < 0) { // default package
1978 result = packageAssertionStatus.get(null);
1979 if (result != null)
1980 return result.booleanValue();
1981 }
1982 while(dotIndex > 0) {
1983 className = className.substring(0, dotIndex);
1984 result = packageAssertionStatus.get(className);
1985 if (result != null)
1986 return result.booleanValue();
1987 dotIndex = className.lastIndexOf(".", dotIndex-1);
1988 }
1989
1990 // Return the classloader default
1991 return defaultAssertionStatus;
1992 }
1993
1994 // Set up the assertions with information provided by the VM.
1995 private void initializeJavaAssertionMaps() {
1996 // assert Thread.holdsLock(this);
1997
1998 classAssertionStatus = new HashMap<String, Boolean>();
1999 packageAssertionStatus = new HashMap<String, Boolean>();
2000 AssertionStatusDirectives directives = retrieveDirectives();
2001
2002 for(int i = 0; i < directives.classes.length; i++)
2003 classAssertionStatus.put(directives.classes[i],
2004 directives.classEnabled[i]);
2005
2006 for(int i = 0; i < directives.packages.length; i++)
2007 packageAssertionStatus.put(directives.packages[i],
2008 directives.packageEnabled[i]);
2009
2010 defaultAssertionStatus = directives.deflt;
2011 }
2012
2013 // Retrieves the assertion directives from the VM.
2014 private static native AssertionStatusDirectives retrieveDirectives();
2015 }
2016
2017
2018 class SystemClassLoaderAction
2019 implements PrivilegedExceptionAction<ClassLoader> {
2020 private ClassLoader parent;
2021
2022 SystemClassLoaderAction(ClassLoader parent) {
2023 this.parent = parent;
2024 }
2025
2026 public ClassLoader run() throws Exception {
2027 String cls = System.getProperty("java.system.class.loader");
2028 if (cls == null) {
2029 return parent;
2030 }
2031
2032 Constructor ctor = Class.forName(cls, true, parent)
2033 .getDeclaredConstructor(new Class[] { ClassLoader.class });
2034 ClassLoader sys = (ClassLoader) ctor.newInstance(
2035 new Object[] { parent });
2036 Thread.currentThread().setContextClassLoader(sys);
2037 return sys;
2038 }
2039 }
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