1 /*
2 * Copyright (c) 1994, 2014, 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.*;
28 import java.lang.reflect.Executable;
29 import java.lang.annotation.Annotation;
30 import java.security.AccessControlContext;
31 import java.util.Properties;
32 import java.util.PropertyPermission;
33 import java.util.StringTokenizer;
34 import java.util.Map;
35 import java.security.AccessController;
36 import java.security.PrivilegedAction;
37 import java.security.AllPermission;
38 import java.nio.channels.Channel;
39 import java.nio.channels.spi.SelectorProvider;
40 import sun.nio.ch.Interruptible;
41 import sun.reflect.CallerSensitive;
42 import sun.reflect.Reflection;
43 import sun.security.util.SecurityConstants;
44 import sun.reflect.annotation.AnnotationType;
45
46 /**
47 * The <code>System</code> class contains several useful class fields
48 * and methods. It cannot be instantiated.
49 *
50 * <p>Among the facilities provided by the <code>System</code> class
51 * are standard input, standard output, and error output streams;
52 * access to externally defined properties and environment
53 * variables; a means of loading files and libraries; and a utility
54 * method for quickly copying a portion of an array.
55 *
56 * @author unascribed
57 * @since 1.0
58 */
59 public final class System {
60
61 /* register the natives via the static initializer.
62 *
63 * VM will invoke the initializeSystemClass method to complete
64 * the initialization for this class separated from clinit.
65 * Note that to use properties set by the VM, see the constraints
66 * described in the initializeSystemClass method.
67 */
68 private static native void registerNatives();
69 static {
70 registerNatives();
71 }
72
73 /** Don't let anyone instantiate this class */
74 private System() {
75 }
76
77 /**
78 * The "standard" input stream. This stream is already
79 * open and ready to supply input data. Typically this stream
80 * corresponds to keyboard input or another input source specified by
81 * the host environment or user.
82 */
83 public final static InputStream in = null;
84
85 /**
86 * The "standard" output stream. This stream is already
87 * open and ready to accept output data. Typically this stream
88 * corresponds to display output or another output destination
89 * specified by the host environment or user.
90 * <p>
91 * For simple stand-alone Java applications, a typical way to write
92 * a line of output data is:
93 * <blockquote><pre>
94 * System.out.println(data)
95 * </pre></blockquote>
96 * <p>
97 * See the <code>println</code> methods in class <code>PrintStream</code>.
98 *
99 * @see java.io.PrintStream#println()
100 * @see java.io.PrintStream#println(boolean)
101 * @see java.io.PrintStream#println(char)
102 * @see java.io.PrintStream#println(char[])
103 * @see java.io.PrintStream#println(double)
104 * @see java.io.PrintStream#println(float)
105 * @see java.io.PrintStream#println(int)
106 * @see java.io.PrintStream#println(long)
107 * @see java.io.PrintStream#println(java.lang.Object)
108 * @see java.io.PrintStream#println(java.lang.String)
109 */
110 public final static PrintStream out = null;
111
112 /**
113 * The "standard" error output stream. This stream is already
114 * open and ready to accept output data.
115 * <p>
116 * Typically this stream corresponds to display output or another
117 * output destination specified by the host environment or user. By
118 * convention, this output stream is used to display error messages
119 * or other information that should come to the immediate attention
120 * of a user even if the principal output stream, the value of the
121 * variable <code>out</code>, has been redirected to a file or other
122 * destination that is typically not continuously monitored.
123 */
124 public final static PrintStream err = null;
125
126 /* The security manager for the system.
127 */
128 private static volatile SecurityManager security = null;
129
130 /**
131 * Reassigns the "standard" input stream.
132 *
133 * <p>First, if there is a security manager, its <code>checkPermission</code>
134 * method is called with a <code>RuntimePermission("setIO")</code> permission
135 * to see if it's ok to reassign the "standard" input stream.
136 *
137 * @param in the new standard input stream.
138 *
139 * @throws SecurityException
140 * if a security manager exists and its
141 * <code>checkPermission</code> method doesn't allow
142 * reassigning of the standard input stream.
143 *
144 * @see SecurityManager#checkPermission
145 * @see java.lang.RuntimePermission
146 *
147 * @since 1.1
148 */
149 public static void setIn(InputStream in) {
150 checkIO();
151 setIn0(in);
152 }
153
154 /**
155 * Reassigns the "standard" output stream.
156 *
157 * <p>First, if there is a security manager, its <code>checkPermission</code>
158 * method is called with a <code>RuntimePermission("setIO")</code> permission
159 * to see if it's ok to reassign the "standard" output stream.
160 *
161 * @param out the new standard output stream
162 *
163 * @throws SecurityException
164 * if a security manager exists and its
165 * <code>checkPermission</code> method doesn't allow
166 * reassigning of the standard output stream.
167 *
168 * @see SecurityManager#checkPermission
169 * @see java.lang.RuntimePermission
170 *
171 * @since 1.1
172 */
173 public static void setOut(PrintStream out) {
174 checkIO();
175 setOut0(out);
176 }
177
178 /**
179 * Reassigns the "standard" error output stream.
180 *
181 * <p>First, if there is a security manager, its <code>checkPermission</code>
182 * method is called with a <code>RuntimePermission("setIO")</code> permission
183 * to see if it's ok to reassign the "standard" error output stream.
184 *
185 * @param err the new standard error output stream.
186 *
187 * @throws SecurityException
188 * if a security manager exists and its
189 * <code>checkPermission</code> method doesn't allow
190 * reassigning of the standard error output stream.
191 *
192 * @see SecurityManager#checkPermission
193 * @see java.lang.RuntimePermission
194 *
195 * @since 1.1
196 */
197 public static void setErr(PrintStream err) {
198 checkIO();
199 setErr0(err);
200 }
201
202 private static volatile Console cons = null;
203 /**
204 * Returns the unique {@link java.io.Console Console} object associated
205 * with the current Java virtual machine, if any.
206 *
207 * @return The system console, if any, otherwise <tt>null</tt>.
208 *
209 * @since 1.6
210 */
211 public static Console console() {
212 if (cons == null) {
213 synchronized (System.class) {
214 cons = sun.misc.SharedSecrets.getJavaIOAccess().console();
215 }
216 }
217 return cons;
218 }
219
220 /**
221 * Returns the channel inherited from the entity that created this
222 * Java virtual machine.
223 *
224 * <p> This method returns the channel obtained by invoking the
225 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
226 * inheritedChannel} method of the system-wide default
227 * {@link java.nio.channels.spi.SelectorProvider} object. </p>
228 *
229 * <p> In addition to the network-oriented channels described in
230 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
231 * inheritedChannel}, this method may return other kinds of
232 * channels in the future.
233 *
234 * @return The inherited channel, if any, otherwise <tt>null</tt>.
235 *
236 * @throws IOException
237 * If an I/O error occurs
238 *
239 * @throws SecurityException
240 * If a security manager is present and it does not
241 * permit access to the channel.
242 *
243 * @since 1.5
244 */
245 public static Channel inheritedChannel() throws IOException {
246 return SelectorProvider.provider().inheritedChannel();
247 }
248
249 private static void checkIO() {
250 SecurityManager sm = getSecurityManager();
251 if (sm != null) {
252 sm.checkPermission(new RuntimePermission("setIO"));
253 }
254 }
255
256 private static native void setIn0(InputStream in);
257 private static native void setOut0(PrintStream out);
258 private static native void setErr0(PrintStream err);
259
260 /**
261 * Sets the System security.
262 *
263 * <p> If there is a security manager already installed, this method first
264 * calls the security manager's <code>checkPermission</code> method
265 * with a <code>RuntimePermission("setSecurityManager")</code>
266 * permission to ensure it's ok to replace the existing
267 * security manager.
268 * This may result in throwing a <code>SecurityException</code>.
269 *
270 * <p> Otherwise, the argument is established as the current
271 * security manager. If the argument is <code>null</code> and no
272 * security manager has been established, then no action is taken and
273 * the method simply returns.
274 *
275 * @param s the security manager.
276 * @exception SecurityException if the security manager has already
277 * been set and its <code>checkPermission</code> method
278 * doesn't allow it to be replaced.
279 * @see #getSecurityManager
280 * @see SecurityManager#checkPermission
281 * @see java.lang.RuntimePermission
282 */
283 public static
284 void setSecurityManager(final SecurityManager s) {
285 try {
286 s.checkPackageAccess("java.lang");
287 } catch (Exception e) {
288 // no-op
289 }
290 setSecurityManager0(s);
291 }
292
293 private static synchronized
294 void setSecurityManager0(final SecurityManager s) {
295 SecurityManager sm = getSecurityManager();
296 if (sm != null) {
297 // ask the currently installed security manager if we
298 // can replace it.
299 sm.checkPermission(new RuntimePermission
300 ("setSecurityManager"));
301 }
302
303 if ((s != null) && (s.getClass().getClassLoader() != null)) {
304 // New security manager class is not on bootstrap classpath.
305 // Cause policy to get initialized before we install the new
306 // security manager, in order to prevent infinite loops when
307 // trying to initialize the policy (which usually involves
308 // accessing some security and/or system properties, which in turn
309 // calls the installed security manager's checkPermission method
310 // which will loop infinitely if there is a non-system class
311 // (in this case: the new security manager class) on the stack).
312 AccessController.doPrivileged(new PrivilegedAction<Object>() {
313 public Object run() {
314 s.getClass().getProtectionDomain().implies
315 (SecurityConstants.ALL_PERMISSION);
316 return null;
317 }
318 });
319 }
320
321 security = s;
322 }
323
324 /**
325 * Gets the system security interface.
326 *
327 * @return if a security manager has already been established for the
328 * current application, then that security manager is returned;
329 * otherwise, <code>null</code> is returned.
330 * @see #setSecurityManager
331 */
332 public static SecurityManager getSecurityManager() {
333 return security;
334 }
335
336 /**
337 * Returns the current time in milliseconds. Note that
338 * while the unit of time of the return value is a millisecond,
339 * the granularity of the value depends on the underlying
340 * operating system and may be larger. For example, many
341 * operating systems measure time in units of tens of
342 * milliseconds.
343 *
344 * <p> See the description of the class <code>Date</code> for
345 * a discussion of slight discrepancies that may arise between
346 * "computer time" and coordinated universal time (UTC).
347 *
348 * @return the difference, measured in milliseconds, between
349 * the current time and midnight, January 1, 1970 UTC.
350 * @see java.util.Date
351 */
352 public static native long currentTimeMillis();
353
354 /**
355 * Returns the current value of the running Java Virtual Machine's
356 * high-resolution time source, in nanoseconds.
357 *
358 * <p>This method can only be used to measure elapsed time and is
359 * not related to any other notion of system or wall-clock time.
360 * The value returned represents nanoseconds since some fixed but
361 * arbitrary <i>origin</i> time (perhaps in the future, so values
362 * may be negative). The same origin is used by all invocations of
363 * this method in an instance of a Java virtual machine; other
364 * virtual machine instances are likely to use a different origin.
365 *
366 * <p>This method provides nanosecond precision, but not necessarily
367 * nanosecond resolution (that is, how frequently the value changes)
368 * - no guarantees are made except that the resolution is at least as
369 * good as that of {@link #currentTimeMillis()}.
370 *
371 * <p>Differences in successive calls that span greater than
372 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
373 * correctly compute elapsed time due to numerical overflow.
374 *
375 * <p>The values returned by this method become meaningful only when
376 * the difference between two such values, obtained within the same
377 * instance of a Java virtual machine, is computed.
378 *
379 * <p> For example, to measure how long some code takes to execute:
380 * <pre> {@code
381 * long startTime = System.nanoTime();
382 * // ... the code being measured ...
383 * long estimatedTime = System.nanoTime() - startTime;}</pre>
384 *
385 * <p>To compare two nanoTime values
386 * <pre> {@code
387 * long t0 = System.nanoTime();
388 * ...
389 * long t1 = System.nanoTime();}</pre>
390 *
391 * one should use {@code t1 - t0 < 0}, not {@code t1 < t0},
392 * because of the possibility of numerical overflow.
393 *
394 * @return the current value of the running Java Virtual Machine's
395 * high-resolution time source, in nanoseconds
396 * @since 1.5
397 */
398 public static native long nanoTime();
399
400 /**
401 * Copies an array from the specified source array, beginning at the
402 * specified position, to the specified position of the destination array.
403 * A subsequence of array components are copied from the source
404 * array referenced by <code>src</code> to the destination array
405 * referenced by <code>dest</code>. The number of components copied is
406 * equal to the <code>length</code> argument. The components at
407 * positions <code>srcPos</code> through
408 * <code>srcPos+length-1</code> in the source array are copied into
409 * positions <code>destPos</code> through
410 * <code>destPos+length-1</code>, respectively, of the destination
411 * array.
412 * <p>
413 * If the <code>src</code> and <code>dest</code> arguments refer to the
414 * same array object, then the copying is performed as if the
415 * components at positions <code>srcPos</code> through
416 * <code>srcPos+length-1</code> were first copied to a temporary
417 * array with <code>length</code> components and then the contents of
418 * the temporary array were copied into positions
419 * <code>destPos</code> through <code>destPos+length-1</code> of the
420 * destination array.
421 * <p>
422 * If <code>dest</code> is <code>null</code>, then a
423 * <code>NullPointerException</code> is thrown.
424 * <p>
425 * If <code>src</code> is <code>null</code>, then a
426 * <code>NullPointerException</code> is thrown and the destination
427 * array is not modified.
428 * <p>
429 * Otherwise, if any of the following is true, an
430 * <code>ArrayStoreException</code> is thrown and the destination is
431 * not modified:
432 * <ul>
433 * <li>The <code>src</code> argument refers to an object that is not an
434 * array.
435 * <li>The <code>dest</code> argument refers to an object that is not an
436 * array.
437 * <li>The <code>src</code> argument and <code>dest</code> argument refer
438 * to arrays whose component types are different primitive types.
439 * <li>The <code>src</code> argument refers to an array with a primitive
440 * component type and the <code>dest</code> argument refers to an array
441 * with a reference component type.
442 * <li>The <code>src</code> argument refers to an array with a reference
443 * component type and the <code>dest</code> argument refers to an array
444 * with a primitive component type.
445 * </ul>
446 * <p>
447 * Otherwise, if any of the following is true, an
448 * <code>IndexOutOfBoundsException</code> is
449 * thrown and the destination is not modified:
450 * <ul>
451 * <li>The <code>srcPos</code> argument is negative.
452 * <li>The <code>destPos</code> argument is negative.
453 * <li>The <code>length</code> argument is negative.
454 * <li><code>srcPos+length</code> is greater than
455 * <code>src.length</code>, the length of the source array.
456 * <li><code>destPos+length</code> is greater than
457 * <code>dest.length</code>, the length of the destination array.
458 * </ul>
459 * <p>
460 * Otherwise, if any actual component of the source array from
461 * position <code>srcPos</code> through
462 * <code>srcPos+length-1</code> cannot be converted to the component
463 * type of the destination array by assignment conversion, an
464 * <code>ArrayStoreException</code> is thrown. In this case, let
465 * <b><i>k</i></b> be the smallest nonnegative integer less than
466 * length such that <code>src[srcPos+</code><i>k</i><code>]</code>
467 * cannot be converted to the component type of the destination
468 * array; when the exception is thrown, source array components from
469 * positions <code>srcPos</code> through
470 * <code>srcPos+</code><i>k</i><code>-1</code>
471 * will already have been copied to destination array positions
472 * <code>destPos</code> through
473 * <code>destPos+</code><i>k</I><code>-1</code> and no other
474 * positions of the destination array will have been modified.
475 * (Because of the restrictions already itemized, this
476 * paragraph effectively applies only to the situation where both
477 * arrays have component types that are reference types.)
478 *
479 * @param src the source array.
480 * @param srcPos starting position in the source array.
481 * @param dest the destination array.
482 * @param destPos starting position in the destination data.
483 * @param length the number of array elements to be copied.
484 * @exception IndexOutOfBoundsException if copying would cause
485 * access of data outside array bounds.
486 * @exception ArrayStoreException if an element in the <code>src</code>
487 * array could not be stored into the <code>dest</code> array
488 * because of a type mismatch.
489 * @exception NullPointerException if either <code>src</code> or
490 * <code>dest</code> is <code>null</code>.
491 */
492 public static native void arraycopy(Object src, int srcPos,
493 Object dest, int destPos,
494 int length);
495
496 /**
497 * Returns the same hash code for the given object as
498 * would be returned by the default method hashCode(),
499 * whether or not the given object's class overrides
500 * hashCode().
501 * The hash code for the null reference is zero.
502 *
503 * @param x object for which the hashCode is to be calculated
504 * @return the hashCode
505 * @since 1.1
506 */
507 public static native int identityHashCode(Object x);
508
509 /**
510 * System properties. The following properties are guaranteed to be defined:
511 * <dl>
512 * <dt>java.version <dd>Java version number
513 * <dt>java.vendor <dd>Java vendor specific string
514 * <dt>java.vendor.url <dd>Java vendor URL
515 * <dt>java.home <dd>Java installation directory
516 * <dt>java.class.version <dd>Java class version number
517 * <dt>java.class.path <dd>Java classpath
518 * <dt>os.name <dd>Operating System Name
519 * <dt>os.arch <dd>Operating System Architecture
520 * <dt>os.version <dd>Operating System Version
521 * <dt>file.separator <dd>File separator ("/" on Unix)
522 * <dt>path.separator <dd>Path separator (":" on Unix)
523 * <dt>line.separator <dd>Line separator ("\n" on Unix)
524 * <dt>user.name <dd>User account name
525 * <dt>user.home <dd>User home directory
526 * <dt>user.dir <dd>User's current working directory
527 * </dl>
528 */
529
530 private static Properties props;
531 private static native Properties initProperties(Properties props);
532
533 /**
534 * Determines the current system properties.
535 * <p>
536 * First, if there is a security manager, its
537 * <code>checkPropertiesAccess</code> method is called with no
538 * arguments. This may result in a security exception.
539 * <p>
540 * The current set of system properties for use by the
541 * {@link #getProperty(String)} method is returned as a
542 * <code>Properties</code> object. If there is no current set of
543 * system properties, a set of system properties is first created and
544 * initialized. This set of system properties always includes values
545 * for the following keys:
546 * <table summary="Shows property keys and associated values">
547 * <tr><th>Key</th>
548 * <th>Description of Associated Value</th></tr>
549 * <tr><td><code>java.version</code></td>
550 * <td>Java Runtime Environment version</td></tr>
551 * <tr><td><code>java.vendor</code></td>
552 * <td>Java Runtime Environment vendor</td></tr>
553 * <tr><td><code>java.vendor.url</code></td>
554 * <td>Java vendor URL</td></tr>
555 * <tr><td><code>java.home</code></td>
556 * <td>Java installation directory</td></tr>
557 * <tr><td><code>java.vm.specification.version</code></td>
558 * <td>Java Virtual Machine specification version</td></tr>
559 * <tr><td><code>java.vm.specification.vendor</code></td>
560 * <td>Java Virtual Machine specification vendor</td></tr>
561 * <tr><td><code>java.vm.specification.name</code></td>
562 * <td>Java Virtual Machine specification name</td></tr>
563 * <tr><td><code>java.vm.version</code></td>
564 * <td>Java Virtual Machine implementation version</td></tr>
565 * <tr><td><code>java.vm.vendor</code></td>
566 * <td>Java Virtual Machine implementation vendor</td></tr>
567 * <tr><td><code>java.vm.name</code></td>
568 * <td>Java Virtual Machine implementation name</td></tr>
569 * <tr><td><code>java.specification.version</code></td>
570 * <td>Java Runtime Environment specification version</td></tr>
571 * <tr><td><code>java.specification.vendor</code></td>
572 * <td>Java Runtime Environment specification vendor</td></tr>
573 * <tr><td><code>java.specification.name</code></td>
574 * <td>Java Runtime Environment specification name</td></tr>
575 * <tr><td><code>java.class.version</code></td>
576 * <td>Java class format version number</td></tr>
577 * <tr><td><code>java.class.path</code></td>
578 * <td>Java class path</td></tr>
579 * <tr><td><code>java.library.path</code></td>
580 * <td>List of paths to search when loading libraries</td></tr>
581 * <tr><td><code>java.io.tmpdir</code></td>
582 * <td>Default temp file path</td></tr>
583 * <tr><td><code>java.compiler</code></td>
584 * <td>Name of JIT compiler to use</td></tr>
585 * <tr><td><code>os.name</code></td>
586 * <td>Operating system name</td></tr>
587 * <tr><td><code>os.arch</code></td>
588 * <td>Operating system architecture</td></tr>
589 * <tr><td><code>os.version</code></td>
590 * <td>Operating system version</td></tr>
591 * <tr><td><code>file.separator</code></td>
592 * <td>File separator ("/" on UNIX)</td></tr>
593 * <tr><td><code>path.separator</code></td>
594 * <td>Path separator (":" on UNIX)</td></tr>
595 * <tr><td><code>line.separator</code></td>
596 * <td>Line separator ("\n" on UNIX)</td></tr>
597 * <tr><td><code>user.name</code></td>
598 * <td>User's account name</td></tr>
599 * <tr><td><code>user.home</code></td>
600 * <td>User's home directory</td></tr>
601 * <tr><td><code>user.dir</code></td>
602 * <td>User's current working directory</td></tr>
603 * </table>
604 * <p>
605 * Multiple paths in a system property value are separated by the path
606 * separator character of the platform.
607 * <p>
608 * Note that even if the security manager does not permit the
609 * <code>getProperties</code> operation, it may choose to permit the
610 * {@link #getProperty(String)} operation.
611 *
612 * @return the system properties
613 * @exception SecurityException if a security manager exists and its
614 * <code>checkPropertiesAccess</code> method doesn't allow access
615 * to the system properties.
616 * @see #setProperties
617 * @see java.lang.SecurityException
618 * @see java.lang.SecurityManager#checkPropertiesAccess()
619 * @see java.util.Properties
620 */
621 public static Properties getProperties() {
622 SecurityManager sm = getSecurityManager();
623 if (sm != null) {
624 sm.checkPropertiesAccess();
625 }
626
627 return props;
628 }
629
630 /**
631 * Returns the system-dependent line separator string. It always
632 * returns the same value - the initial value of the {@linkplain
633 * #getProperty(String) system property} {@code line.separator}.
634 *
635 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
636 * Windows systems it returns {@code "\r\n"}.
637 *
638 * @return the system-dependent line separator string
639 * @since 1.7
640 */
641 public static String lineSeparator() {
642 return lineSeparator;
643 }
644
645 private static String lineSeparator;
646
647 /**
648 * Sets the system properties to the <code>Properties</code>
649 * argument.
650 * <p>
651 * First, if there is a security manager, its
652 * <code>checkPropertiesAccess</code> method is called with no
653 * arguments. This may result in a security exception.
654 * <p>
655 * The argument becomes the current set of system properties for use
656 * by the {@link #getProperty(String)} method. If the argument is
657 * <code>null</code>, then the current set of system properties is
658 * forgotten.
659 *
660 * @param props the new system properties.
661 * @exception SecurityException if a security manager exists and its
662 * <code>checkPropertiesAccess</code> method doesn't allow access
663 * to the system properties.
664 * @see #getProperties
665 * @see java.util.Properties
666 * @see java.lang.SecurityException
667 * @see java.lang.SecurityManager#checkPropertiesAccess()
668 */
669 public static void setProperties(Properties props) {
670 SecurityManager sm = getSecurityManager();
671 if (sm != null) {
672 sm.checkPropertiesAccess();
673 }
674 if (props == null) {
675 props = new Properties();
676 initProperties(props);
677 }
678 System.props = props;
679 }
680
681 /**
682 * Gets the system property indicated by the specified key.
683 * <p>
684 * First, if there is a security manager, its
685 * <code>checkPropertyAccess</code> method is called with the key as
686 * its argument. This may result in a SecurityException.
687 * <p>
688 * If there is no current set of system properties, a set of system
689 * properties is first created and initialized in the same manner as
690 * for the <code>getProperties</code> method.
691 *
692 * @param key the name of the system property.
693 * @return the string value of the system property,
694 * or <code>null</code> if there is no property with that key.
695 *
696 * @exception SecurityException if a security manager exists and its
697 * <code>checkPropertyAccess</code> method doesn't allow
698 * access to the specified system property.
699 * @exception NullPointerException if <code>key</code> is
700 * <code>null</code>.
701 * @exception IllegalArgumentException if <code>key</code> is empty.
702 * @see #setProperty
703 * @see java.lang.SecurityException
704 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
705 * @see java.lang.System#getProperties()
706 */
707 public static String getProperty(String key) {
708 checkKey(key);
709 SecurityManager sm = getSecurityManager();
710 if (sm != null) {
711 sm.checkPropertyAccess(key);
712 }
713
714 return props.getProperty(key);
715 }
716
717 /**
718 * Gets the system property indicated by the specified key.
719 * <p>
720 * First, if there is a security manager, its
721 * <code>checkPropertyAccess</code> method is called with the
722 * <code>key</code> as its argument.
723 * <p>
724 * If there is no current set of system properties, a set of system
725 * properties is first created and initialized in the same manner as
726 * for the <code>getProperties</code> method.
727 *
728 * @param key the name of the system property.
729 * @param def a default value.
730 * @return the string value of the system property,
731 * or the default value if there is no property with that key.
732 *
733 * @exception SecurityException if a security manager exists and its
734 * <code>checkPropertyAccess</code> method doesn't allow
735 * access to the specified system property.
736 * @exception NullPointerException if <code>key</code> is
737 * <code>null</code>.
738 * @exception IllegalArgumentException if <code>key</code> is empty.
739 * @see #setProperty
740 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
741 * @see java.lang.System#getProperties()
742 */
743 public static String getProperty(String key, String def) {
744 checkKey(key);
745 SecurityManager sm = getSecurityManager();
746 if (sm != null) {
747 sm.checkPropertyAccess(key);
748 }
749
750 return props.getProperty(key, def);
751 }
752
753 /**
754 * Sets the system property indicated by the specified key.
755 * <p>
756 * First, if a security manager exists, its
757 * <code>SecurityManager.checkPermission</code> method
758 * is called with a <code>PropertyPermission(key, "write")</code>
759 * permission. This may result in a SecurityException being thrown.
760 * If no exception is thrown, the specified property is set to the given
761 * value.
762 *
763 * @param key the name of the system property.
764 * @param value the value of the system property.
765 * @return the previous value of the system property,
766 * or <code>null</code> if it did not have one.
767 *
768 * @exception SecurityException if a security manager exists and its
769 * <code>checkPermission</code> method doesn't allow
770 * setting of the specified property.
771 * @exception NullPointerException if <code>key</code> or
772 * <code>value</code> is <code>null</code>.
773 * @exception IllegalArgumentException if <code>key</code> is empty.
774 * @see #getProperty
775 * @see java.lang.System#getProperty(java.lang.String)
776 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
777 * @see java.util.PropertyPermission
778 * @see SecurityManager#checkPermission
779 * @since 1.2
780 */
781 public static String setProperty(String key, String value) {
782 checkKey(key);
783 SecurityManager sm = getSecurityManager();
784 if (sm != null) {
785 sm.checkPermission(new PropertyPermission(key,
786 SecurityConstants.PROPERTY_WRITE_ACTION));
787 }
788
789 return (String) props.setProperty(key, value);
790 }
791
792 /**
793 * Removes the system property indicated by the specified key.
794 * <p>
795 * First, if a security manager exists, its
796 * <code>SecurityManager.checkPermission</code> method
797 * is called with a <code>PropertyPermission(key, "write")</code>
798 * permission. This may result in a SecurityException being thrown.
799 * If no exception is thrown, the specified property is removed.
800 *
801 * @param key the name of the system property to be removed.
802 * @return the previous string value of the system property,
803 * or <code>null</code> if there was no property with that key.
804 *
805 * @exception SecurityException if a security manager exists and its
806 * <code>checkPropertyAccess</code> method doesn't allow
807 * access to the specified system property.
808 * @exception NullPointerException if <code>key</code> is
809 * <code>null</code>.
810 * @exception IllegalArgumentException if <code>key</code> is empty.
811 * @see #getProperty
812 * @see #setProperty
813 * @see java.util.Properties
814 * @see java.lang.SecurityException
815 * @see java.lang.SecurityManager#checkPropertiesAccess()
816 * @since 1.5
817 */
818 public static String clearProperty(String key) {
819 checkKey(key);
820 SecurityManager sm = getSecurityManager();
821 if (sm != null) {
822 sm.checkPermission(new PropertyPermission(key, "write"));
823 }
824
825 return (String) props.remove(key);
826 }
827
828 private static void checkKey(String key) {
829 if (key == null) {
830 throw new NullPointerException("key can't be null");
831 }
832 if (key.equals("")) {
833 throw new IllegalArgumentException("key can't be empty");
834 }
835 }
836
837 /**
838 * Gets the value of the specified environment variable. An
839 * environment variable is a system-dependent external named
840 * value.
841 *
842 * <p>If a security manager exists, its
843 * {@link SecurityManager#checkPermission checkPermission}
844 * method is called with a
845 * <code>{@link RuntimePermission}("getenv."+name)</code>
846 * permission. This may result in a {@link SecurityException}
847 * being thrown. If no exception is thrown the value of the
848 * variable <code>name</code> is returned.
849 *
850 * <p><a name="EnvironmentVSSystemProperties"><i>System
851 * properties</i> and <i>environment variables</i></a> are both
852 * conceptually mappings between names and values. Both
853 * mechanisms can be used to pass user-defined information to a
854 * Java process. Environment variables have a more global effect,
855 * because they are visible to all descendants of the process
856 * which defines them, not just the immediate Java subprocess.
857 * They can have subtly different semantics, such as case
858 * insensitivity, on different operating systems. For these
859 * reasons, environment variables are more likely to have
860 * unintended side effects. It is best to use system properties
861 * where possible. Environment variables should be used when a
862 * global effect is desired, or when an external system interface
863 * requires an environment variable (such as <code>PATH</code>).
864 *
865 * <p>On UNIX systems the alphabetic case of <code>name</code> is
866 * typically significant, while on Microsoft Windows systems it is
867 * typically not. For example, the expression
868 * <code>System.getenv("FOO").equals(System.getenv("foo"))</code>
869 * is likely to be true on Microsoft Windows.
870 *
871 * @param name the name of the environment variable
872 * @return the string value of the variable, or <code>null</code>
873 * if the variable is not defined in the system environment
874 * @throws NullPointerException if <code>name</code> is <code>null</code>
875 * @throws SecurityException
876 * if a security manager exists and its
877 * {@link SecurityManager#checkPermission checkPermission}
878 * method doesn't allow access to the environment variable
879 * <code>name</code>
880 * @see #getenv()
881 * @see ProcessBuilder#environment()
882 */
883 public static String getenv(String name) {
884 SecurityManager sm = getSecurityManager();
885 if (sm != null) {
886 sm.checkPermission(new RuntimePermission("getenv."+name));
887 }
888
889 return ProcessEnvironment.getenv(name);
890 }
891
892
893 /**
894 * Returns an unmodifiable string map view of the current system environment.
895 * The environment is a system-dependent mapping from names to
896 * values which is passed from parent to child processes.
897 *
898 * <p>If the system does not support environment variables, an
899 * empty map is returned.
900 *
901 * <p>The returned map will never contain null keys or values.
902 * Attempting to query the presence of a null key or value will
903 * throw a {@link NullPointerException}. Attempting to query
904 * the presence of a key or value which is not of type
905 * {@link String} will throw a {@link ClassCastException}.
906 *
907 * <p>The returned map and its collection views may not obey the
908 * general contract of the {@link Object#equals} and
909 * {@link Object#hashCode} methods.
910 *
911 * <p>The returned map is typically case-sensitive on all platforms.
912 *
913 * <p>If a security manager exists, its
914 * {@link SecurityManager#checkPermission checkPermission}
915 * method is called with a
916 * <code>{@link RuntimePermission}("getenv.*")</code>
917 * permission. This may result in a {@link SecurityException} being
918 * thrown.
919 *
920 * <p>When passing information to a Java subprocess,
921 * <a href=#EnvironmentVSSystemProperties>system properties</a>
922 * are generally preferred over environment variables.
923 *
924 * @return the environment as a map of variable names to values
925 * @throws SecurityException
926 * if a security manager exists and its
927 * {@link SecurityManager#checkPermission checkPermission}
928 * method doesn't allow access to the process environment
929 * @see #getenv(String)
930 * @see ProcessBuilder#environment()
931 * @since 1.5
932 */
933 public static java.util.Map<String,String> getenv() {
934 SecurityManager sm = getSecurityManager();
935 if (sm != null) {
936 sm.checkPermission(new RuntimePermission("getenv.*"));
937 }
938
939 return ProcessEnvironment.getenv();
940 }
941
942 /**
943 * Terminates the currently running Java Virtual Machine. The
944 * argument serves as a status code; by convention, a nonzero status
945 * code indicates abnormal termination.
946 * <p>
947 * This method calls the <code>exit</code> method in class
948 * <code>Runtime</code>. This method never returns normally.
949 * <p>
950 * The call <code>System.exit(n)</code> is effectively equivalent to
951 * the call:
952 * <blockquote><pre>
953 * Runtime.getRuntime().exit(n)
954 * </pre></blockquote>
955 *
956 * @param status exit status.
957 * @throws SecurityException
958 * if a security manager exists and its <code>checkExit</code>
959 * method doesn't allow exit with the specified status.
960 * @see java.lang.Runtime#exit(int)
961 */
962 public static void exit(int status) {
963 Runtime.getRuntime().exit(status);
964 }
965
966 /**
967 * Runs the garbage collector.
968 * <p>
969 * Calling the <code>gc</code> method suggests that the Java Virtual
970 * Machine expend effort toward recycling unused objects in order to
971 * make the memory they currently occupy available for quick reuse.
972 * When control returns from the method call, the Java Virtual
973 * Machine has made a best effort to reclaim space from all discarded
974 * objects.
975 * <p>
976 * The call <code>System.gc()</code> is effectively equivalent to the
977 * call:
978 * <blockquote><pre>
979 * Runtime.getRuntime().gc()
980 * </pre></blockquote>
981 *
982 * @see java.lang.Runtime#gc()
983 */
984 public static void gc() {
985 Runtime.getRuntime().gc();
986 }
987
988 /**
989 * Runs the finalization methods of any objects pending finalization.
990 * <p>
991 * Calling this method suggests that the Java Virtual Machine expend
992 * effort toward running the <code>finalize</code> methods of objects
993 * that have been found to be discarded but whose <code>finalize</code>
994 * methods have not yet been run. When control returns from the
995 * method call, the Java Virtual Machine has made a best effort to
996 * complete all outstanding finalizations.
997 * <p>
998 * The call <code>System.runFinalization()</code> is effectively
999 * equivalent to the call:
1000 * <blockquote><pre>
1001 * Runtime.getRuntime().runFinalization()
1002 * </pre></blockquote>
1003 *
1004 * @see java.lang.Runtime#runFinalization()
1005 */
1006 public static void runFinalization() {
1007 Runtime.getRuntime().runFinalization();
1008 }
1009
1010 /**
1011 * Enable or disable finalization on exit; doing so specifies that the
1012 * finalizers of all objects that have finalizers that have not yet been
1013 * automatically invoked are to be run before the Java runtime exits.
1014 * By default, finalization on exit is disabled.
1015 *
1016 * <p>If there is a security manager,
1017 * its <code>checkExit</code> method is first called
1018 * with 0 as its argument to ensure the exit is allowed.
1019 * This could result in a SecurityException.
1020 *
1021 * @deprecated This method is inherently unsafe. It may result in
1022 * finalizers being called on live objects while other threads are
1023 * concurrently manipulating those objects, resulting in erratic
1024 * behavior or deadlock.
1025 * @param value indicating enabling or disabling of finalization
1026 * @throws SecurityException
1027 * if a security manager exists and its <code>checkExit</code>
1028 * method doesn't allow the exit.
1029 *
1030 * @see java.lang.Runtime#exit(int)
1031 * @see java.lang.Runtime#gc()
1032 * @see java.lang.SecurityManager#checkExit(int)
1033 * @since 1.1
1034 */
1035 @Deprecated
1036 public static void runFinalizersOnExit(boolean value) {
1037 Runtime.runFinalizersOnExit(value);
1038 }
1039
1040 /**
1041 * Loads the native library specified by the filename argument. The filename
1042 * argument must be an absolute path name.
1043 *
1044 * If the filename argument, when stripped of any platform-specific library
1045 * prefix, path, and file extension, indicates a library whose name is,
1046 * for example, L, and a native library called L is statically linked
1047 * with the VM, then the JNI_OnLoad_L function exported by the library
1048 * is invoked rather than attempting to load a dynamic library.
1049 * A filename matching the argument does not have to exist in the
1050 * file system.
1051 * See the JNI Specification for more details.
1052 *
1053 * Otherwise, the filename argument is mapped to a native library image in
1054 * an implementation-dependent manner.
1055 *
1056 * <p>
1057 * The call <code>System.load(name)</code> is effectively equivalent
1058 * to the call:
1059 * <blockquote><pre>
1060 * Runtime.getRuntime().load(name)
1061 * </pre></blockquote>
1062 *
1063 * @param filename the file to load.
1064 * @exception SecurityException if a security manager exists and its
1065 * <code>checkLink</code> method doesn't allow
1066 * loading of the specified dynamic library
1067 * @exception UnsatisfiedLinkError if either the filename is not an
1068 * absolute path name, the native library is not statically
1069 * linked with the VM, or the library cannot be mapped to
1070 * a native library image by the host system.
1071 * @exception NullPointerException if <code>filename</code> is
1072 * <code>null</code>
1073 * @see java.lang.Runtime#load(java.lang.String)
1074 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1075 */
1076 @CallerSensitive
1077 public static void load(String filename) {
1078 Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
1079 }
1080
1081 /**
1082 * Loads the native library specified by the <code>libname</code>
1083 * argument. The <code>libname</code> argument must not contain any platform
1084 * specific prefix, file extension or path. If a native library
1085 * called <code>libname</code> is statically linked with the VM, then the
1086 * JNI_OnLoad_<code>libname</code> function exported by the library is invoked.
1087 * See the JNI Specification for more details.
1088 *
1089 * Otherwise, the libname argument is loaded from a system library
1090 * location and mapped to a native library image in an implementation-
1091 * dependent manner.
1092 * <p>
1093 * The call <code>System.loadLibrary(name)</code> is effectively
1094 * equivalent to the call
1095 * <blockquote><pre>
1096 * Runtime.getRuntime().loadLibrary(name)
1097 * </pre></blockquote>
1098 *
1099 * @param libname the name of the library.
1100 * @exception SecurityException if a security manager exists and its
1101 * <code>checkLink</code> method doesn't allow
1102 * loading of the specified dynamic library
1103 * @exception UnsatisfiedLinkError if either the libname argument
1104 * contains a file path, the native library is not statically
1105 * linked with the VM, or the library cannot be mapped to a
1106 * native library image by the host system.
1107 * @exception NullPointerException if <code>libname</code> is
1108 * <code>null</code>
1109 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1110 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1111 */
1112 @CallerSensitive
1113 public static void loadLibrary(String libname) {
1114 Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
1115 }
1116
1117 /**
1118 * Maps a library name into a platform-specific string representing
1119 * a native library.
1120 *
1121 * @param libname the name of the library.
1122 * @return a platform-dependent native library name.
1123 * @exception NullPointerException if <code>libname</code> is
1124 * <code>null</code>
1125 * @see java.lang.System#loadLibrary(java.lang.String)
1126 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1127 * @since 1.2
1128 */
1129 public static native String mapLibraryName(String libname);
1130
1131 /**
1132 * Create PrintStream for stdout/err based on encoding.
1133 */
1134 private static PrintStream newPrintStream(FileOutputStream fos, String enc) {
1135 if (enc != null) {
1136 try {
1137 return new PrintStream(new BufferedOutputStream(fos, 128), true, enc);
1138 } catch (UnsupportedEncodingException uee) {}
1139 }
1140 return new PrintStream(new BufferedOutputStream(fos, 128), true);
1141 }
1142
1143
1144 /**
1145 * Initialize the system class. Called after thread initialization.
1146 */
1147 private static void initializeSystemClass() {
1148
1149 // VM might invoke JNU_NewStringPlatform() to set those encoding
1150 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1151 // during "props" initialization, in which it may need access, via
1152 // System.getProperty(), to the related system encoding property that
1153 // have been initialized (put into "props") at early stage of the
1154 // initialization. So make sure the "props" is available at the
1155 // very beginning of the initialization and all system properties to
1156 // be put into it directly.
1157 props = new Properties();
1158 initProperties(props); // initialized by the VM
1159
1160 // There are certain system configurations that may be controlled by
1161 // VM options such as the maximum amount of direct memory and
1162 // Integer cache size used to support the object identity semantics
1163 // of autoboxing. Typically, the library will obtain these values
1164 // from the properties set by the VM. If the properties are for
1165 // internal implementation use only, these properties should be
1166 // removed from the system properties.
1167 //
1168 // See java.lang.Integer.IntegerCache and the
1169 // sun.misc.VM.saveAndRemoveProperties method for example.
1170 //
1171 // Save a private copy of the system properties object that
1172 // can only be accessed by the internal implementation. Remove
1173 // certain system properties that are not intended for public access.
1174 sun.misc.VM.saveAndRemoveProperties(props);
1175
1176
1177 lineSeparator = props.getProperty("line.separator");
1178 sun.misc.Version.init();
1179
1180 FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
1181 FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
1182 FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
1183 setIn0(new BufferedInputStream(fdIn));
1184 setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")));
1185 setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding")));
1186
1187 // Load the zip library now in order to keep java.util.zip.ZipFile
1188 // from trying to use itself to load this library later.
1189 loadLibrary("zip");
1190
1191 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1192 Terminator.setup();
1193
1194 // Initialize any miscellaneous operating system settings that need to be
1195 // set for the class libraries. Currently this is no-op everywhere except
1196 // for Windows where the process-wide error mode is set before the java.io
1197 // classes are used.
1198 sun.misc.VM.initializeOSEnvironment();
1199
1200 // The main thread is not added to its thread group in the same
1201 // way as other threads; we must do it ourselves here.
1202 Thread current = Thread.currentThread();
1203 current.getThreadGroup().add(current);
1204
1205 // register shared secrets
1206 setJavaLangAccess();
1207
1208 // Subsystems that are invoked during initialization can invoke
1209 // sun.misc.VM.isBooted() in order to avoid doing things that should
1210 // wait until the application class loader has been set up.
1211 // IMPORTANT: Ensure that this remains the last initialization action!
1212 sun.misc.VM.booted();
1213 }
1214
1215 private static void setJavaLangAccess() {
1216 // Allow privileged classes outside of java.lang
1217 sun.misc.SharedSecrets.setJavaLangAccess(new sun.misc.JavaLangAccess(){
1218 public sun.reflect.ConstantPool getConstantPool(Class<?> klass) {
1219 return klass.getConstantPool();
1220 }
1221 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
1222 return klass.casAnnotationType(oldType, newType);
1223 }
1224 public AnnotationType getAnnotationType(Class<?> klass) {
1225 return klass.getAnnotationType();
1226 }
1227 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
1228 return klass.getDeclaredAnnotationMap();
1229 }
1230 public byte[] getRawClassAnnotations(Class<?> klass) {
1231 return klass.getRawAnnotations();
1232 }
1233 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
1234 return klass.getRawTypeAnnotations();
1235 }
1236 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
1237 return Class.getExecutableTypeAnnotationBytes(executable);
1238 }
1239 public <E extends Enum<E>>
1240 E[] getEnumConstantsShared(Class<E> klass) {
1241 return klass.getEnumConstantsShared();
1242 }
1243 public void blockedOn(Thread t, Interruptible b) {
1244 t.blockedOn(b);
1245 }
1246 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
1247 Shutdown.add(slot, registerShutdownInProgress, hook);
1248 }
1249 public int getStackTraceDepth(Throwable t) {
1250 return t.getStackTraceDepth();
1251 }
1252 public StackTraceElement getStackTraceElement(Throwable t, int i) {
1253 return t.getStackTraceElement(i);
1254 }
1255 public String newStringUnsafe(char[] chars) {
1256 return new String(chars, true);
1257 }
1258 public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) {
1259 return new Thread(target, acc);
1260 }
1261 public void invokeFinalize(Object o) throws Throwable {
1262 o.finalize();
1263 }
1264 public void formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
1265 Long.formatUnsignedLong(val, shift, buf, offset, len);
1266 }
1267 public void formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
1268 Integer.formatUnsignedInt(val, shift, buf, offset, len);
1269 }
1270 });
1271 }
1272 }