1 /*
2 * Copyright (c) 1994, 2013, 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.util.Properties;
30 import java.util.PropertyPermission;
31 import java.util.StringTokenizer;
32 import java.security.AccessController;
33 import java.security.PrivilegedAction;
34 import java.security.AllPermission;
35 import java.nio.channels.Channel;
36 import java.nio.channels.spi.SelectorProvider;
37 import sun.nio.ch.Interruptible;
38 import sun.reflect.CallerSensitive;
39 import sun.reflect.Reflection;
40 import sun.security.util.SecurityConstants;
41 import sun.reflect.annotation.AnnotationType;
42
43 /**
44 * The <code>System</code> class contains several useful class fields
45 * and methods. It cannot be instantiated.
46 *
47 * <p>Among the facilities provided by the <code>System</code> class
48 * are standard input, standard output, and error output streams;
49 * access to externally defined properties and environment
50 * variables; a means of loading files and libraries; and a utility
51 * method for quickly copying a portion of an array.
52 *
53 * @author unascribed
54 * @since JDK1.0
55 */
56 public final class System {
57
58 /* register the natives via the static initializer.
59 *
60 * VM will invoke the initializeSystemClass method to complete
61 * the initialization for this class separated from clinit.
62 * Note that to use properties set by the VM, see the constraints
63 * described in the initializeSystemClass method.
64 */
65 private static native void registerNatives();
66 static {
67 registerNatives();
68 }
69
70 /** Don't let anyone instantiate this class */
71 private System() {
72 }
73
74 /**
75 * The "standard" input stream. This stream is already
76 * open and ready to supply input data. Typically this stream
77 * corresponds to keyboard input or another input source specified by
78 * the host environment or user.
79 */
80 public final static InputStream in = null;
81
82 /**
83 * The "standard" output stream. This stream is already
84 * open and ready to accept output data. Typically this stream
85 * corresponds to display output or another output destination
86 * specified by the host environment or user.
87 * <p>
88 * For simple stand-alone Java applications, a typical way to write
89 * a line of output data is:
90 * <blockquote><pre>
91 * System.out.println(data)
92 * </pre></blockquote>
93 * <p>
94 * See the <code>println</code> methods in class <code>PrintStream</code>.
95 *
96 * @see java.io.PrintStream#println()
97 * @see java.io.PrintStream#println(boolean)
98 * @see java.io.PrintStream#println(char)
99 * @see java.io.PrintStream#println(char[])
100 * @see java.io.PrintStream#println(double)
101 * @see java.io.PrintStream#println(float)
102 * @see java.io.PrintStream#println(int)
103 * @see java.io.PrintStream#println(long)
104 * @see java.io.PrintStream#println(java.lang.Object)
105 * @see java.io.PrintStream#println(java.lang.String)
106 */
107 public final static PrintStream out = null;
108
109 /**
110 * The "standard" error output stream. This stream is already
111 * open and ready to accept output data.
112 * <p>
113 * Typically this stream corresponds to display output or another
114 * output destination specified by the host environment or user. By
115 * convention, this output stream is used to display error messages
116 * or other information that should come to the immediate attention
117 * of a user even if the principal output stream, the value of the
118 * variable <code>out</code>, has been redirected to a file or other
119 * destination that is typically not continuously monitored.
120 */
121 public final static PrintStream err = null;
122
123 /* The security manager for the system.
124 */
125 private static volatile SecurityManager security = null;
126
127 /**
128 * Reassigns the "standard" input stream.
129 *
130 * <p>First, if there is a security manager, its <code>checkPermission</code>
131 * method is called with a <code>RuntimePermission("setIO")</code> permission
132 * to see if it's ok to reassign the "standard" input stream.
133 * <p>
134 *
135 * @param in the new standard input stream.
136 *
137 * @throws SecurityException
138 * if a security manager exists and its
139 * <code>checkPermission</code> method doesn't allow
140 * reassigning of the standard input stream.
141 *
142 * @see SecurityManager#checkPermission
143 * @see java.lang.RuntimePermission
144 *
145 * @since JDK1.1
146 */
147 public static void setIn(InputStream in) {
148 checkIO();
149 setIn0(in);
150 }
151
152 /**
153 * Reassigns the "standard" output stream.
154 *
155 * <p>First, if there is a security manager, its <code>checkPermission</code>
156 * method is called with a <code>RuntimePermission("setIO")</code> permission
157 * to see if it's ok to reassign the "standard" output stream.
158 *
159 * @param out the new standard output stream
160 *
161 * @throws SecurityException
162 * if a security manager exists and its
163 * <code>checkPermission</code> method doesn't allow
164 * reassigning of the standard output stream.
165 *
166 * @see SecurityManager#checkPermission
167 * @see java.lang.RuntimePermission
168 *
169 * @since JDK1.1
170 */
171 public static void setOut(PrintStream out) {
172 checkIO();
173 setOut0(out);
174 }
175
176 /**
177 * Reassigns the "standard" error output stream.
178 *
179 * <p>First, if there is a security manager, its <code>checkPermission</code>
180 * method is called with a <code>RuntimePermission("setIO")</code> permission
181 * to see if it's ok to reassign the "standard" error output stream.
182 *
183 * @param err the new standard error output stream.
184 *
185 * @throws SecurityException
186 * if a security manager exists and its
187 * <code>checkPermission</code> method doesn't allow
188 * reassigning of the standard error output stream.
189 *
190 * @see SecurityManager#checkPermission
191 * @see java.lang.RuntimePermission
192 *
193 * @since JDK1.1
194 */
195 public static void setErr(PrintStream err) {
196 checkIO();
197 setErr0(err);
198 }
199
200 private static volatile Console cons = null;
201 /**
202 * Returns the unique {@link java.io.Console Console} object associated
203 * with the current Java virtual machine, if any.
204 *
205 * @return The system console, if any, otherwise <tt>null</tt>.
206 *
207 * @since 1.6
208 */
209 public static Console console() {
210 if (cons == null) {
211 synchronized (System.class) {
212 cons = sun.misc.SharedSecrets.getJavaIOAccess().console();
213 }
214 }
215 return cons;
216 }
217
218 /**
219 * Returns the channel inherited from the entity that created this
220 * Java virtual machine.
221 *
222 * <p> This method returns the channel obtained by invoking the
223 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
224 * inheritedChannel} method of the system-wide default
225 * {@link java.nio.channels.spi.SelectorProvider} object. </p>
226 *
227 * <p> In addition to the network-oriented channels described in
228 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
229 * inheritedChannel}, this method may return other kinds of
230 * channels in the future.
231 *
232 * @return The inherited channel, if any, otherwise <tt>null</tt>.
233 *
234 * @throws IOException
235 * If an I/O error occurs
236 *
237 * @throws SecurityException
238 * If a security manager is present and it does not
239 * permit access to the channel.
240 *
241 * @since 1.5
242 */
243 public static Channel inheritedChannel() throws IOException {
244 return SelectorProvider.provider().inheritedChannel();
245 }
246
247 private static void checkIO() {
248 SecurityManager sm = getSecurityManager();
249 if (sm != null) {
250 sm.checkPermission(new RuntimePermission("setIO"));
251 }
252 }
253
254 private static native void setIn0(InputStream in);
255 private static native void setOut0(PrintStream out);
256 private static native void setErr0(PrintStream err);
257
258 /**
259 * Sets the System security.
260 *
261 * <p> If there is a security manager already installed, this method first
262 * calls the security manager's <code>checkPermission</code> method
263 * with a <code>RuntimePermission("setSecurityManager")</code>
264 * permission to ensure it's ok to replace the existing
265 * security manager.
266 * This may result in throwing a <code>SecurityException</code>.
267 *
268 * <p> Otherwise, the argument is established as the current
269 * security manager. If the argument is <code>null</code> and no
270 * security manager has been established, then no action is taken and
271 * the method simply returns.
272 *
273 * @param s the security manager.
274 * @exception SecurityException if the security manager has already
275 * been set and its <code>checkPermission</code> method
276 * doesn't allow it to be replaced.
277 * @see #getSecurityManager
278 * @see SecurityManager#checkPermission
279 * @see java.lang.RuntimePermission
280 */
281 public static
282 void setSecurityManager(final SecurityManager s) {
283 try {
284 s.checkPackageAccess("java.lang");
285 } catch (Exception e) {
286 // no-op
287 }
288 setSecurityManager0(s);
289 }
290
291 private static synchronized
292 void setSecurityManager0(final SecurityManager s) {
293 SecurityManager sm = getSecurityManager();
294 if (sm != null) {
295 // ask the currently installed security manager if we
296 // can replace it.
297 sm.checkPermission(new RuntimePermission
298 ("setSecurityManager"));
299 }
300
301 if ((s != null) && (s.getClass().getClassLoader() != null)) {
302 // New security manager class is not on bootstrap classpath.
303 // Cause policy to get initialized before we install the new
304 // security manager, in order to prevent infinite loops when
305 // trying to initialize the policy (which usually involves
306 // accessing some security and/or system properties, which in turn
307 // calls the installed security manager's checkPermission method
308 // which will loop infinitely if there is a non-system class
309 // (in this case: the new security manager class) on the stack).
310 AccessController.doPrivileged(new PrivilegedAction<Object>() {
311 public Object run() {
312 s.getClass().getProtectionDomain().implies
313 (SecurityConstants.ALL_PERMISSION);
314 return null;
315 }
316 });
317 }
318
319 security = s;
320 }
321
322 /**
323 * Gets the system security interface.
324 *
325 * @return if a security manager has already been established for the
326 * current application, then that security manager is returned;
327 * otherwise, <code>null</code> is returned.
328 * @see #setSecurityManager
329 */
330 public static SecurityManager getSecurityManager() {
331 return security;
332 }
333
334 /**
335 * Returns the current time in milliseconds. Note that
336 * while the unit of time of the return value is a millisecond,
337 * the granularity of the value depends on the underlying
338 * operating system and may be larger. For example, many
339 * operating systems measure time in units of tens of
340 * milliseconds.
341 *
342 * <p> See the description of the class <code>Date</code> for
343 * a discussion of slight discrepancies that may arise between
344 * "computer time" and coordinated universal time (UTC).
345 *
346 * @return the difference, measured in milliseconds, between
347 * the current time and midnight, January 1, 1970 UTC.
348 * @see java.util.Date
349 */
350 public static native long currentTimeMillis();
351
352 /**
353 * Returns the current value of the running Java Virtual Machine's
354 * high-resolution time source, in nanoseconds.
355 *
356 * <p>This method can only be used to measure elapsed time and is
357 * not related to any other notion of system or wall-clock time.
358 * The value returned represents nanoseconds since some fixed but
359 * arbitrary <i>origin</i> time (perhaps in the future, so values
360 * may be negative). The same origin is used by all invocations of
361 * this method in an instance of a Java virtual machine; other
362 * virtual machine instances are likely to use a different origin.
363 *
364 * <p>This method provides nanosecond precision, but not necessarily
365 * nanosecond resolution (that is, how frequently the value changes)
366 * - no guarantees are made except that the resolution is at least as
367 * good as that of {@link #currentTimeMillis()}.
368 *
369 * <p>Differences in successive calls that span greater than
370 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
371 * correctly compute elapsed time due to numerical overflow.
372 *
373 * <p>The values returned by this method become meaningful only when
374 * the difference between two such values, obtained within the same
375 * instance of a Java virtual machine, is computed.
376 *
377 * <p> For example, to measure how long some code takes to execute:
378 * <pre> {@code
379 * long startTime = System.nanoTime();
380 * // ... the code being measured ...
381 * long estimatedTime = System.nanoTime() - startTime;}</pre>
382 *
383 * <p>To compare two nanoTime values
384 * <pre> {@code
385 * long t0 = System.nanoTime();
386 * ...
387 * long t1 = System.nanoTime();}</pre>
388 *
389 * one should use {@code t1 - t0 < 0}, not {@code t1 < t0},
390 * because of the possibility of numerical overflow.
391 *
392 * @return the current value of the running Java Virtual Machine's
393 * high-resolution time source, in nanoseconds
394 * @since 1.5
395 */
396 public static native long nanoTime();
397
398 /**
399 * Copies an array from the specified source array, beginning at the
400 * specified position, to the specified position of the destination array.
401 * A subsequence of array components are copied from the source
402 * array referenced by <code>src</code> to the destination array
403 * referenced by <code>dest</code>. The number of components copied is
404 * equal to the <code>length</code> argument. The components at
405 * positions <code>srcPos</code> through
406 * <code>srcPos+length-1</code> in the source array are copied into
407 * positions <code>destPos</code> through
408 * <code>destPos+length-1</code>, respectively, of the destination
409 * array.
410 * <p>
411 * If the <code>src</code> and <code>dest</code> arguments refer to the
412 * same array object, then the copying is performed as if the
413 * components at positions <code>srcPos</code> through
414 * <code>srcPos+length-1</code> were first copied to a temporary
415 * array with <code>length</code> components and then the contents of
416 * the temporary array were copied into positions
417 * <code>destPos</code> through <code>destPos+length-1</code> of the
418 * destination array.
419 * <p>
420 * If <code>dest</code> is <code>null</code>, then a
421 * <code>NullPointerException</code> is thrown.
422 * <p>
423 * If <code>src</code> is <code>null</code>, then a
424 * <code>NullPointerException</code> is thrown and the destination
425 * array is not modified.
426 * <p>
427 * Otherwise, if any of the following is true, an
428 * <code>ArrayStoreException</code> is thrown and the destination is
429 * not modified:
430 * <ul>
431 * <li>The <code>src</code> argument refers to an object that is not an
432 * array.
433 * <li>The <code>dest</code> argument refers to an object that is not an
434 * array.
435 * <li>The <code>src</code> argument and <code>dest</code> argument refer
436 * to arrays whose component types are different primitive types.
437 * <li>The <code>src</code> argument refers to an array with a primitive
438 * component type and the <code>dest</code> argument refers to an array
439 * with a reference component type.
440 * <li>The <code>src</code> argument refers to an array with a reference
441 * component type and the <code>dest</code> argument refers to an array
442 * with a primitive component type.
443 * </ul>
444 * <p>
445 * Otherwise, if any of the following is true, an
446 * <code>IndexOutOfBoundsException</code> is
447 * thrown and the destination is not modified:
448 * <ul>
449 * <li>The <code>srcPos</code> argument is negative.
450 * <li>The <code>destPos</code> argument is negative.
451 * <li>The <code>length</code> argument is negative.
452 * <li><code>srcPos+length</code> is greater than
453 * <code>src.length</code>, the length of the source array.
454 * <li><code>destPos+length</code> is greater than
455 * <code>dest.length</code>, the length of the destination array.
456 * </ul>
457 * <p>
458 * Otherwise, if any actual component of the source array from
459 * position <code>srcPos</code> through
460 * <code>srcPos+length-1</code> cannot be converted to the component
461 * type of the destination array by assignment conversion, an
462 * <code>ArrayStoreException</code> is thrown. In this case, let
463 * <b><i>k</i></b> be the smallest nonnegative integer less than
464 * length such that <code>src[srcPos+</code><i>k</i><code>]</code>
465 * cannot be converted to the component type of the destination
466 * array; when the exception is thrown, source array components from
467 * positions <code>srcPos</code> through
468 * <code>srcPos+</code><i>k</i><code>-1</code>
469 * will already have been copied to destination array positions
470 * <code>destPos</code> through
471 * <code>destPos+</code><i>k</I><code>-1</code> and no other
472 * positions of the destination array will have been modified.
473 * (Because of the restrictions already itemized, this
474 * paragraph effectively applies only to the situation where both
475 * arrays have component types that are reference types.)
476 *
477 * @param src the source array.
478 * @param srcPos starting position in the source array.
479 * @param dest the destination array.
480 * @param destPos starting position in the destination data.
481 * @param length the number of array elements to be copied.
482 * @exception IndexOutOfBoundsException if copying would cause
483 * access of data outside array bounds.
484 * @exception ArrayStoreException if an element in the <code>src</code>
485 * array could not be stored into the <code>dest</code> array
486 * because of a type mismatch.
487 * @exception NullPointerException if either <code>src</code> or
488 * <code>dest</code> is <code>null</code>.
489 */
490 public static native void arraycopy(Object src, int srcPos,
491 Object dest, int destPos,
492 int length);
493
494 /**
495 * Returns the same hash code for the given object as
496 * would be returned by the default method hashCode(),
497 * whether or not the given object's class overrides
498 * hashCode().
499 * The hash code for the null reference is zero.
500 *
501 * @param x object for which the hashCode is to be calculated
502 * @return the hashCode
503 * @since JDK1.1
504 */
505 public static native int identityHashCode(Object x);
506
507 /**
508 * System properties. The following properties are guaranteed to be defined:
509 * <dl>
510 * <dt>java.version <dd>Java version number
511 * <dt>java.vendor <dd>Java vendor specific string
512 * <dt>java.vendor.url <dd>Java vendor URL
513 * <dt>java.home <dd>Java installation directory
514 * <dt>java.class.version <dd>Java class version number
515 * <dt>java.class.path <dd>Java classpath
516 * <dt>os.name <dd>Operating System Name
517 * <dt>os.arch <dd>Operating System Architecture
518 * <dt>os.version <dd>Operating System Version
519 * <dt>file.separator <dd>File separator ("/" on Unix)
520 * <dt>path.separator <dd>Path separator (":" on Unix)
521 * <dt>line.separator <dd>Line separator ("\n" on Unix)
522 * <dt>user.name <dd>User account name
523 * <dt>user.home <dd>User home directory
524 * <dt>user.dir <dd>User's current working directory
525 * </dl>
526 */
527
528 private static Properties props;
529 private static native Properties initProperties(Properties props);
530
531 /**
532 * Determines the current system properties.
533 * <p>
534 * First, if there is a security manager, its
535 * <code>checkPropertiesAccess</code> method is called with no
536 * arguments. This may result in a security exception.
537 * <p>
538 * The current set of system properties for use by the
539 * {@link #getProperty(String)} method is returned as a
540 * <code>Properties</code> object. If there is no current set of
541 * system properties, a set of system properties is first created and
542 * initialized. This set of system properties always includes values
543 * for the following keys:
544 * <table summary="Shows property keys and associated values">
545 * <tr><th>Key</th>
546 * <th>Description of Associated Value</th></tr>
547 * <tr><td><code>java.version</code></td>
548 * <td>Java Runtime Environment version</td></tr>
549 * <tr><td><code>java.vendor</code></td>
550 * <td>Java Runtime Environment vendor</td></tr>
551 * <tr><td><code>java.vendor.url</code></td>
552 * <td>Java vendor URL</td></tr>
553 * <tr><td><code>java.home</code></td>
554 * <td>Java installation directory</td></tr>
555 * <tr><td><code>java.vm.specification.version</code></td>
556 * <td>Java Virtual Machine specification version</td></tr>
557 * <tr><td><code>java.vm.specification.vendor</code></td>
558 * <td>Java Virtual Machine specification vendor</td></tr>
559 * <tr><td><code>java.vm.specification.name</code></td>
560 * <td>Java Virtual Machine specification name</td></tr>
561 * <tr><td><code>java.vm.version</code></td>
562 * <td>Java Virtual Machine implementation version</td></tr>
563 * <tr><td><code>java.vm.vendor</code></td>
564 * <td>Java Virtual Machine implementation vendor</td></tr>
565 * <tr><td><code>java.vm.name</code></td>
566 * <td>Java Virtual Machine implementation name</td></tr>
567 * <tr><td><code>java.specification.version</code></td>
568 * <td>Java Runtime Environment specification version</td></tr>
569 * <tr><td><code>java.specification.vendor</code></td>
570 * <td>Java Runtime Environment specification vendor</td></tr>
571 * <tr><td><code>java.specification.name</code></td>
572 * <td>Java Runtime Environment specification name</td></tr>
573 * <tr><td><code>java.class.version</code></td>
574 * <td>Java class format version number</td></tr>
575 * <tr><td><code>java.class.path</code></td>
576 * <td>Java class path</td></tr>
577 * <tr><td><code>java.library.path</code></td>
578 * <td>List of paths to search when loading libraries</td></tr>
579 * <tr><td><code>java.io.tmpdir</code></td>
580 * <td>Default temp file path</td></tr>
581 * <tr><td><code>java.compiler</code></td>
582 * <td>Name of JIT compiler to use</td></tr>
583 * <tr><td><code>java.ext.dirs</code></td>
584 * <td>Path of extension directory or directories</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 * @since 1.7
638 */
639 public static String lineSeparator() {
640 return lineSeparator;
641 }
642
643 private static String lineSeparator;
644
645 /**
646 * Sets the system properties to the <code>Properties</code>
647 * argument.
648 * <p>
649 * First, if there is a security manager, its
650 * <code>checkPropertiesAccess</code> method is called with no
651 * arguments. This may result in a security exception.
652 * <p>
653 * The argument becomes the current set of system properties for use
654 * by the {@link #getProperty(String)} method. If the argument is
655 * <code>null</code>, then the current set of system properties is
656 * forgotten.
657 *
658 * @param props the new system properties.
659 * @exception SecurityException if a security manager exists and its
660 * <code>checkPropertiesAccess</code> method doesn't allow access
661 * to the system properties.
662 * @see #getProperties
663 * @see java.util.Properties
664 * @see java.lang.SecurityException
665 * @see java.lang.SecurityManager#checkPropertiesAccess()
666 */
667 public static void setProperties(Properties props) {
668 SecurityManager sm = getSecurityManager();
669 if (sm != null) {
670 sm.checkPropertiesAccess();
671 }
672 if (props == null) {
673 props = new Properties();
674 initProperties(props);
675 }
676 System.props = props;
677 }
678
679 /**
680 * Gets the system property indicated by the specified key.
681 * <p>
682 * First, if there is a security manager, its
683 * <code>checkPropertyAccess</code> method is called with the key as
684 * its argument. This may result in a SecurityException.
685 * <p>
686 * If there is no current set of system properties, a set of system
687 * properties is first created and initialized in the same manner as
688 * for the <code>getProperties</code> method.
689 *
690 * @param key the name of the system property.
691 * @return the string value of the system property,
692 * or <code>null</code> if there is no property with that key.
693 *
694 * @exception SecurityException if a security manager exists and its
695 * <code>checkPropertyAccess</code> method doesn't allow
696 * access to the specified system property.
697 * @exception NullPointerException if <code>key</code> is
698 * <code>null</code>.
699 * @exception IllegalArgumentException if <code>key</code> is empty.
700 * @see #setProperty
701 * @see java.lang.SecurityException
702 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
703 * @see java.lang.System#getProperties()
704 */
705 public static String getProperty(String key) {
706 checkKey(key);
707 SecurityManager sm = getSecurityManager();
708 if (sm != null) {
709 sm.checkPropertyAccess(key);
710 }
711
712 return props.getProperty(key);
713 }
714
715 /**
716 * Gets the system property indicated by the specified key.
717 * <p>
718 * First, if there is a security manager, its
719 * <code>checkPropertyAccess</code> method is called with the
720 * <code>key</code> as its argument.
721 * <p>
722 * If there is no current set of system properties, a set of system
723 * properties is first created and initialized in the same manner as
724 * for the <code>getProperties</code> method.
725 *
726 * @param key the name of the system property.
727 * @param def a default value.
728 * @return the string value of the system property,
729 * or the default value if there is no property with that key.
730 *
731 * @exception SecurityException if a security manager exists and its
732 * <code>checkPropertyAccess</code> method doesn't allow
733 * access to the specified system property.
734 * @exception NullPointerException if <code>key</code> is
735 * <code>null</code>.
736 * @exception IllegalArgumentException if <code>key</code> is empty.
737 * @see #setProperty
738 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
739 * @see java.lang.System#getProperties()
740 */
741 public static String getProperty(String key, String def) {
742 checkKey(key);
743 SecurityManager sm = getSecurityManager();
744 if (sm != null) {
745 sm.checkPropertyAccess(key);
746 }
747
748 return props.getProperty(key, def);
749 }
750
751 /**
752 * Sets the system property indicated by the specified key.
753 * <p>
754 * First, if a security manager exists, its
755 * <code>SecurityManager.checkPermission</code> method
756 * is called with a <code>PropertyPermission(key, "write")</code>
757 * permission. This may result in a SecurityException being thrown.
758 * If no exception is thrown, the specified property is set to the given
759 * value.
760 * <p>
761 *
762 * @param key the name of the system property.
763 * @param value the value of the system property.
764 * @return the previous value of the system property,
765 * or <code>null</code> if it did not have one.
766 *
767 * @exception SecurityException if a security manager exists and its
768 * <code>checkPermission</code> method doesn't allow
769 * setting of the specified property.
770 * @exception NullPointerException if <code>key</code> or
771 * <code>value</code> is <code>null</code>.
772 * @exception IllegalArgumentException if <code>key</code> is empty.
773 * @see #getProperty
774 * @see java.lang.System#getProperty(java.lang.String)
775 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
776 * @see java.util.PropertyPermission
777 * @see SecurityManager#checkPermission
778 * @since 1.2
779 */
780 public static String setProperty(String key, String value) {
781 checkKey(key);
782 SecurityManager sm = getSecurityManager();
783 if (sm != null) {
784 sm.checkPermission(new PropertyPermission(key,
785 SecurityConstants.PROPERTY_WRITE_ACTION));
786 }
787
788 return (String) props.setProperty(key, value);
789 }
790
791 /**
792 * Removes the system property indicated by the specified key.
793 * <p>
794 * First, if a security manager exists, its
795 * <code>SecurityManager.checkPermission</code> method
796 * is called with a <code>PropertyPermission(key, "write")</code>
797 * permission. This may result in a SecurityException being thrown.
798 * If no exception is thrown, the specified property is removed.
799 * <p>
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 JDK1.1
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 miscellenous 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 byte[] getRawClassAnnotations(Class<?> klass) {
1228 return klass.getRawAnnotations();
1229 }
1230 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
1231 return klass.getRawTypeAnnotations();
1232 }
1233 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
1234 return Class.getExecutableTypeAnnotationBytes(executable);
1235 }
1236 public <E extends Enum<E>>
1237 E[] getEnumConstantsShared(Class<E> klass) {
1238 return klass.getEnumConstantsShared();
1239 }
1240 public void blockedOn(Thread t, Interruptible b) {
1241 t.blockedOn(b);
1242 }
1243 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
1244 Shutdown.add(slot, registerShutdownInProgress, hook);
1245 }
1246 public int getStackTraceDepth(Throwable t) {
1247 return t.getStackTraceDepth();
1248 }
1249 public StackTraceElement getStackTraceElement(Throwable t, int i) {
1250 return t.getStackTraceElement(i);
1251 }
1252 public String newStringUnsafe(char[] chars) {
1253 return new String(chars, true);
1254 }
1255 });
1256 }
1257 }