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<>() {
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 elapsedNanos = System.nanoTime() - startTime;}</pre>
384 *
385 * <p>To compare elapsed time against a timeout, use <pre> {@code
386 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
387 * instead of <pre> {@code
388 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
389 * because of the possibility of numerical overflow.
390 *
391 * @return the current value of the running Java Virtual Machine's
392 * high-resolution time source, in nanoseconds
393 * @since 1.5
394 */
395 public static native long nanoTime();
396
397 /**
398 * Copies an array from the specified source array, beginning at the
399 * specified position, to the specified position of the destination array.
400 * A subsequence of array components are copied from the source
401 * array referenced by <code>src</code> to the destination array
402 * referenced by <code>dest</code>. The number of components copied is
403 * equal to the <code>length</code> argument. The components at
404 * positions <code>srcPos</code> through
405 * <code>srcPos+length-1</code> in the source array are copied into
406 * positions <code>destPos</code> through
407 * <code>destPos+length-1</code>, respectively, of the destination
408 * array.
409 * <p>
410 * If the <code>src</code> and <code>dest</code> arguments refer to the
411 * same array object, then the copying is performed as if the
412 * components at positions <code>srcPos</code> through
413 * <code>srcPos+length-1</code> were first copied to a temporary
414 * array with <code>length</code> components and then the contents of
415 * the temporary array were copied into positions
416 * <code>destPos</code> through <code>destPos+length-1</code> of the
417 * destination array.
418 * <p>
419 * If <code>dest</code> is <code>null</code>, then a
420 * <code>NullPointerException</code> is thrown.
421 * <p>
422 * If <code>src</code> is <code>null</code>, then a
423 * <code>NullPointerException</code> is thrown and the destination
424 * array is not modified.
425 * <p>
426 * Otherwise, if any of the following is true, an
427 * <code>ArrayStoreException</code> is thrown and the destination is
428 * not modified:
429 * <ul>
430 * <li>The <code>src</code> argument refers to an object that is not an
431 * array.
432 * <li>The <code>dest</code> argument refers to an object that is not an
433 * array.
434 * <li>The <code>src</code> argument and <code>dest</code> argument refer
435 * to arrays whose component types are different primitive types.
436 * <li>The <code>src</code> argument refers to an array with a primitive
437 * component type and the <code>dest</code> argument refers to an array
438 * with a reference component type.
439 * <li>The <code>src</code> argument refers to an array with a reference
440 * component type and the <code>dest</code> argument refers to an array
441 * with a primitive component type.
442 * </ul>
443 * <p>
444 * Otherwise, if any of the following is true, an
445 * <code>IndexOutOfBoundsException</code> is
446 * thrown and the destination is not modified:
447 * <ul>
448 * <li>The <code>srcPos</code> argument is negative.
449 * <li>The <code>destPos</code> argument is negative.
450 * <li>The <code>length</code> argument is negative.
451 * <li><code>srcPos+length</code> is greater than
452 * <code>src.length</code>, the length of the source array.
453 * <li><code>destPos+length</code> is greater than
454 * <code>dest.length</code>, the length of the destination array.
455 * </ul>
456 * <p>
457 * Otherwise, if any actual component of the source array from
458 * position <code>srcPos</code> through
459 * <code>srcPos+length-1</code> cannot be converted to the component
460 * type of the destination array by assignment conversion, an
461 * <code>ArrayStoreException</code> is thrown. In this case, let
462 * <b><i>k</i></b> be the smallest nonnegative integer less than
463 * length such that <code>src[srcPos+</code><i>k</i><code>]</code>
464 * cannot be converted to the component type of the destination
465 * array; when the exception is thrown, source array components from
466 * positions <code>srcPos</code> through
467 * <code>srcPos+</code><i>k</i><code>-1</code>
468 * will already have been copied to destination array positions
469 * <code>destPos</code> through
470 * <code>destPos+</code><i>k</I><code>-1</code> and no other
471 * positions of the destination array will have been modified.
472 * (Because of the restrictions already itemized, this
473 * paragraph effectively applies only to the situation where both
474 * arrays have component types that are reference types.)
475 *
476 * @param src the source array.
477 * @param srcPos starting position in the source array.
478 * @param dest the destination array.
479 * @param destPos starting position in the destination data.
480 * @param length the number of array elements to be copied.
481 * @exception IndexOutOfBoundsException if copying would cause
482 * access of data outside array bounds.
483 * @exception ArrayStoreException if an element in the <code>src</code>
484 * array could not be stored into the <code>dest</code> array
485 * because of a type mismatch.
486 * @exception NullPointerException if either <code>src</code> or
487 * <code>dest</code> is <code>null</code>.
488 */
489 public static native void arraycopy(Object src, int srcPos,
490 Object dest, int destPos,
491 int length);
492
493 /**
494 * Returns the same hash code for the given object as
495 * would be returned by the default method hashCode(),
496 * whether or not the given object's class overrides
497 * hashCode().
498 * The hash code for the null reference is zero.
499 *
500 * @param x object for which the hashCode is to be calculated
501 * @return the hashCode
502 * @since 1.1
503 */
504 public static native int identityHashCode(Object x);
505
506 /**
507 * System properties. The following properties are guaranteed to be defined:
508 * <dl>
509 * <dt>java.version <dd>Java version number
510 * <dt>java.vendor <dd>Java vendor specific string
511 * <dt>java.vendor.url <dd>Java vendor URL
512 * <dt>java.home <dd>Java installation directory
513 * <dt>java.class.version <dd>Java class version number
514 * <dt>java.class.path <dd>Java classpath
515 * <dt>os.name <dd>Operating System Name
516 * <dt>os.arch <dd>Operating System Architecture
517 * <dt>os.version <dd>Operating System Version
518 * <dt>file.separator <dd>File separator ("/" on Unix)
519 * <dt>path.separator <dd>Path separator (":" on Unix)
520 * <dt>line.separator <dd>Line separator ("\n" on Unix)
521 * <dt>user.name <dd>User account name
522 * <dt>user.home <dd>User home directory
523 * <dt>user.dir <dd>User's current working directory
524 * </dl>
525 */
526
527 private static Properties props;
528 private static native Properties initProperties(Properties props);
529
530 /**
531 * Determines the current system properties.
532 * <p>
533 * First, if there is a security manager, its
534 * <code>checkPropertiesAccess</code> method is called with no
535 * arguments. This may result in a security exception.
536 * <p>
537 * The current set of system properties for use by the
538 * {@link #getProperty(String)} method is returned as a
539 * <code>Properties</code> object. If there is no current set of
540 * system properties, a set of system properties is first created and
541 * initialized. This set of system properties always includes values
542 * for the following keys:
543 * <table summary="Shows property keys and associated values">
544 * <tr><th>Key</th>
545 * <th>Description of Associated Value</th></tr>
546 * <tr><td><code>java.version</code></td>
547 * <td>Java Runtime Environment version</td></tr>
548 * <tr><td><code>java.vendor</code></td>
549 * <td>Java Runtime Environment vendor</td></tr>
550 * <tr><td><code>java.vendor.url</code></td>
551 * <td>Java vendor URL</td></tr>
552 * <tr><td><code>java.home</code></td>
553 * <td>Java installation directory</td></tr>
554 * <tr><td><code>java.vm.specification.version</code></td>
555 * <td>Java Virtual Machine specification version</td></tr>
556 * <tr><td><code>java.vm.specification.vendor</code></td>
557 * <td>Java Virtual Machine specification vendor</td></tr>
558 * <tr><td><code>java.vm.specification.name</code></td>
559 * <td>Java Virtual Machine specification name</td></tr>
560 * <tr><td><code>java.vm.version</code></td>
561 * <td>Java Virtual Machine implementation version</td></tr>
562 * <tr><td><code>java.vm.vendor</code></td>
563 * <td>Java Virtual Machine implementation vendor</td></tr>
564 * <tr><td><code>java.vm.name</code></td>
565 * <td>Java Virtual Machine implementation name</td></tr>
566 * <tr><td><code>java.specification.version</code></td>
567 * <td>Java Runtime Environment specification version</td></tr>
568 * <tr><td><code>java.specification.vendor</code></td>
569 * <td>Java Runtime Environment specification vendor</td></tr>
570 * <tr><td><code>java.specification.name</code></td>
571 * <td>Java Runtime Environment specification name</td></tr>
572 * <tr><td><code>java.class.version</code></td>
573 * <td>Java class format version number</td></tr>
574 * <tr><td><code>java.class.path</code></td>
575 * <td>Java class path</td></tr>
576 * <tr><td><code>java.library.path</code></td>
577 * <td>List of paths to search when loading libraries</td></tr>
578 * <tr><td><code>java.io.tmpdir</code></td>
579 * <td>Default temp file path</td></tr>
580 * <tr><td><code>java.compiler</code></td>
581 * <td>Name of JIT compiler to use</td></tr>
582 * <tr><td><code>os.name</code></td>
583 * <td>Operating system name</td></tr>
584 * <tr><td><code>os.arch</code></td>
585 * <td>Operating system architecture</td></tr>
586 * <tr><td><code>os.version</code></td>
587 * <td>Operating system version</td></tr>
588 * <tr><td><code>file.separator</code></td>
589 * <td>File separator ("/" on UNIX)</td></tr>
590 * <tr><td><code>path.separator</code></td>
591 * <td>Path separator (":" on UNIX)</td></tr>
592 * <tr><td><code>line.separator</code></td>
593 * <td>Line separator ("\n" on UNIX)</td></tr>
594 * <tr><td><code>user.name</code></td>
595 * <td>User's account name</td></tr>
596 * <tr><td><code>user.home</code></td>
597 * <td>User's home directory</td></tr>
598 * <tr><td><code>user.dir</code></td>
599 * <td>User's current working directory</td></tr>
600 * </table>
601 * <p>
602 * Multiple paths in a system property value are separated by the path
603 * separator character of the platform.
604 * <p>
605 * Note that even if the security manager does not permit the
606 * <code>getProperties</code> operation, it may choose to permit the
607 * {@link #getProperty(String)} operation.
608 *
609 * @return the system properties
610 * @exception SecurityException if a security manager exists and its
611 * <code>checkPropertiesAccess</code> method doesn't allow access
612 * to the system properties.
613 * @see #setProperties
614 * @see java.lang.SecurityException
615 * @see java.lang.SecurityManager#checkPropertiesAccess()
616 * @see java.util.Properties
617 */
618 public static Properties getProperties() {
619 SecurityManager sm = getSecurityManager();
620 if (sm != null) {
621 sm.checkPropertiesAccess();
622 }
623
624 return props;
625 }
626
627 /**
628 * Returns the system-dependent line separator string. It always
629 * returns the same value - the initial value of the {@linkplain
630 * #getProperty(String) system property} {@code line.separator}.
631 *
632 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
633 * Windows systems it returns {@code "\r\n"}.
634 *
635 * @return the system-dependent line separator string
636 * @since 1.7
637 */
638 public static String lineSeparator() {
639 return lineSeparator;
640 }
641
642 private static String lineSeparator;
643
644 /**
645 * Sets the system properties to the <code>Properties</code>
646 * argument.
647 * <p>
648 * First, if there is a security manager, its
649 * <code>checkPropertiesAccess</code> method is called with no
650 * arguments. This may result in a security exception.
651 * <p>
652 * The argument becomes the current set of system properties for use
653 * by the {@link #getProperty(String)} method. If the argument is
654 * <code>null</code>, then the current set of system properties is
655 * forgotten.
656 *
657 * @param props the new system properties.
658 * @exception SecurityException if a security manager exists and its
659 * <code>checkPropertiesAccess</code> method doesn't allow access
660 * to the system properties.
661 * @see #getProperties
662 * @see java.util.Properties
663 * @see java.lang.SecurityException
664 * @see java.lang.SecurityManager#checkPropertiesAccess()
665 */
666 public static void setProperties(Properties props) {
667 SecurityManager sm = getSecurityManager();
668 if (sm != null) {
669 sm.checkPropertiesAccess();
670 }
671 if (props == null) {
672 props = new Properties();
673 initProperties(props);
674 }
675 System.props = props;
676 }
677
678 /**
679 * Gets the system property indicated by the specified key.
680 * <p>
681 * First, if there is a security manager, its
682 * <code>checkPropertyAccess</code> method is called with the key as
683 * its argument. This may result in a SecurityException.
684 * <p>
685 * If there is no current set of system properties, a set of system
686 * properties is first created and initialized in the same manner as
687 * for the <code>getProperties</code> method.
688 *
689 * @param key the name of the system property.
690 * @return the string value of the system property,
691 * or <code>null</code> if there is no property with that key.
692 *
693 * @exception SecurityException if a security manager exists and its
694 * <code>checkPropertyAccess</code> method doesn't allow
695 * access to the specified system property.
696 * @exception NullPointerException if <code>key</code> is
697 * <code>null</code>.
698 * @exception IllegalArgumentException if <code>key</code> is empty.
699 * @see #setProperty
700 * @see java.lang.SecurityException
701 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
702 * @see java.lang.System#getProperties()
703 */
704 public static String getProperty(String key) {
705 checkKey(key);
706 SecurityManager sm = getSecurityManager();
707 if (sm != null) {
708 sm.checkPropertyAccess(key);
709 }
710
711 return props.getProperty(key);
712 }
713
714 /**
715 * Gets the system property indicated by the specified key.
716 * <p>
717 * First, if there is a security manager, its
718 * <code>checkPropertyAccess</code> method is called with the
719 * <code>key</code> as its argument.
720 * <p>
721 * If there is no current set of system properties, a set of system
722 * properties is first created and initialized in the same manner as
723 * for the <code>getProperties</code> method.
724 *
725 * @param key the name of the system property.
726 * @param def a default value.
727 * @return the string value of the system property,
728 * or the default value if there is no property with that key.
729 *
730 * @exception SecurityException if a security manager exists and its
731 * <code>checkPropertyAccess</code> method doesn't allow
732 * access to the specified system property.
733 * @exception NullPointerException if <code>key</code> is
734 * <code>null</code>.
735 * @exception IllegalArgumentException if <code>key</code> is empty.
736 * @see #setProperty
737 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
738 * @see java.lang.System#getProperties()
739 */
740 public static String getProperty(String key, String def) {
741 checkKey(key);
742 SecurityManager sm = getSecurityManager();
743 if (sm != null) {
744 sm.checkPropertyAccess(key);
745 }
746
747 return props.getProperty(key, def);
748 }
749
750 /**
751 * Sets the system property indicated by the specified key.
752 * <p>
753 * First, if a security manager exists, its
754 * <code>SecurityManager.checkPermission</code> method
755 * is called with a <code>PropertyPermission(key, "write")</code>
756 * permission. This may result in a SecurityException being thrown.
757 * If no exception is thrown, the specified property is set to the given
758 * value.
759 *
760 * @param key the name of the system property.
761 * @param value the value of the system property.
762 * @return the previous value of the system property,
763 * or <code>null</code> if it did not have one.
764 *
765 * @exception SecurityException if a security manager exists and its
766 * <code>checkPermission</code> method doesn't allow
767 * setting of the specified property.
768 * @exception NullPointerException if <code>key</code> or
769 * <code>value</code> is <code>null</code>.
770 * @exception IllegalArgumentException if <code>key</code> is empty.
771 * @see #getProperty
772 * @see java.lang.System#getProperty(java.lang.String)
773 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
774 * @see java.util.PropertyPermission
775 * @see SecurityManager#checkPermission
776 * @since 1.2
777 */
778 public static String setProperty(String key, String value) {
779 checkKey(key);
780 SecurityManager sm = getSecurityManager();
781 if (sm != null) {
782 sm.checkPermission(new PropertyPermission(key,
783 SecurityConstants.PROPERTY_WRITE_ACTION));
784 }
785
786 return (String) props.setProperty(key, value);
787 }
788
789 /**
790 * Removes the system property indicated by the specified key.
791 * <p>
792 * First, if a security manager exists, its
793 * <code>SecurityManager.checkPermission</code> method
794 * is called with a <code>PropertyPermission(key, "write")</code>
795 * permission. This may result in a SecurityException being thrown.
796 * If no exception is thrown, the specified property is removed.
797 *
798 * @param key the name of the system property to be removed.
799 * @return the previous string value of the system property,
800 * or <code>null</code> if there was no property with that key.
801 *
802 * @exception SecurityException if a security manager exists and its
803 * <code>checkPropertyAccess</code> method doesn't allow
804 * access to the specified system property.
805 * @exception NullPointerException if <code>key</code> is
806 * <code>null</code>.
807 * @exception IllegalArgumentException if <code>key</code> is empty.
808 * @see #getProperty
809 * @see #setProperty
810 * @see java.util.Properties
811 * @see java.lang.SecurityException
812 * @see java.lang.SecurityManager#checkPropertiesAccess()
813 * @since 1.5
814 */
815 public static String clearProperty(String key) {
816 checkKey(key);
817 SecurityManager sm = getSecurityManager();
818 if (sm != null) {
819 sm.checkPermission(new PropertyPermission(key, "write"));
820 }
821
822 return (String) props.remove(key);
823 }
824
825 private static void checkKey(String key) {
826 if (key == null) {
827 throw new NullPointerException("key can't be null");
828 }
829 if (key.equals("")) {
830 throw new IllegalArgumentException("key can't be empty");
831 }
832 }
833
834 /**
835 * Gets the value of the specified environment variable. An
836 * environment variable is a system-dependent external named
837 * value.
838 *
839 * <p>If a security manager exists, its
840 * {@link SecurityManager#checkPermission checkPermission}
841 * method is called with a
842 * <code>{@link RuntimePermission}("getenv."+name)</code>
843 * permission. This may result in a {@link SecurityException}
844 * being thrown. If no exception is thrown the value of the
845 * variable <code>name</code> is returned.
846 *
847 * <p><a name="EnvironmentVSSystemProperties"><i>System
848 * properties</i> and <i>environment variables</i></a> are both
849 * conceptually mappings between names and values. Both
850 * mechanisms can be used to pass user-defined information to a
851 * Java process. Environment variables have a more global effect,
852 * because they are visible to all descendants of the process
853 * which defines them, not just the immediate Java subprocess.
854 * They can have subtly different semantics, such as case
855 * insensitivity, on different operating systems. For these
856 * reasons, environment variables are more likely to have
857 * unintended side effects. It is best to use system properties
858 * where possible. Environment variables should be used when a
859 * global effect is desired, or when an external system interface
860 * requires an environment variable (such as <code>PATH</code>).
861 *
862 * <p>On UNIX systems the alphabetic case of <code>name</code> is
863 * typically significant, while on Microsoft Windows systems it is
864 * typically not. For example, the expression
865 * <code>System.getenv("FOO").equals(System.getenv("foo"))</code>
866 * is likely to be true on Microsoft Windows.
867 *
868 * @param name the name of the environment variable
869 * @return the string value of the variable, or <code>null</code>
870 * if the variable is not defined in the system environment
871 * @throws NullPointerException if <code>name</code> is <code>null</code>
872 * @throws SecurityException
873 * if a security manager exists and its
874 * {@link SecurityManager#checkPermission checkPermission}
875 * method doesn't allow access to the environment variable
876 * <code>name</code>
877 * @see #getenv()
878 * @see ProcessBuilder#environment()
879 */
880 public static String getenv(String name) {
881 SecurityManager sm = getSecurityManager();
882 if (sm != null) {
883 sm.checkPermission(new RuntimePermission("getenv."+name));
884 }
885
886 return ProcessEnvironment.getenv(name);
887 }
888
889
890 /**
891 * Returns an unmodifiable string map view of the current system environment.
892 * The environment is a system-dependent mapping from names to
893 * values which is passed from parent to child processes.
894 *
895 * <p>If the system does not support environment variables, an
896 * empty map is returned.
897 *
898 * <p>The returned map will never contain null keys or values.
899 * Attempting to query the presence of a null key or value will
900 * throw a {@link NullPointerException}. Attempting to query
901 * the presence of a key or value which is not of type
902 * {@link String} will throw a {@link ClassCastException}.
903 *
904 * <p>The returned map and its collection views may not obey the
905 * general contract of the {@link Object#equals} and
906 * {@link Object#hashCode} methods.
907 *
908 * <p>The returned map is typically case-sensitive on all platforms.
909 *
910 * <p>If a security manager exists, its
911 * {@link SecurityManager#checkPermission checkPermission}
912 * method is called with a
913 * <code>{@link RuntimePermission}("getenv.*")</code>
914 * permission. This may result in a {@link SecurityException} being
915 * thrown.
916 *
917 * <p>When passing information to a Java subprocess,
918 * <a href=#EnvironmentVSSystemProperties>system properties</a>
919 * are generally preferred over environment variables.
920 *
921 * @return the environment as a map of variable names to values
922 * @throws SecurityException
923 * if a security manager exists and its
924 * {@link SecurityManager#checkPermission checkPermission}
925 * method doesn't allow access to the process environment
926 * @see #getenv(String)
927 * @see ProcessBuilder#environment()
928 * @since 1.5
929 */
930 public static java.util.Map<String,String> getenv() {
931 SecurityManager sm = getSecurityManager();
932 if (sm != null) {
933 sm.checkPermission(new RuntimePermission("getenv.*"));
934 }
935
936 return ProcessEnvironment.getenv();
937 }
938
939 /**
940 * Terminates the currently running Java Virtual Machine. The
941 * argument serves as a status code; by convention, a nonzero status
942 * code indicates abnormal termination.
943 * <p>
944 * This method calls the <code>exit</code> method in class
945 * <code>Runtime</code>. This method never returns normally.
946 * <p>
947 * The call <code>System.exit(n)</code> is effectively equivalent to
948 * the call:
949 * <blockquote><pre>
950 * Runtime.getRuntime().exit(n)
951 * </pre></blockquote>
952 *
953 * @param status exit status.
954 * @throws SecurityException
955 * if a security manager exists and its <code>checkExit</code>
956 * method doesn't allow exit with the specified status.
957 * @see java.lang.Runtime#exit(int)
958 */
959 public static void exit(int status) {
960 Runtime.getRuntime().exit(status);
961 }
962
963 /**
964 * Runs the garbage collector.
965 * <p>
966 * Calling the <code>gc</code> method suggests that the Java Virtual
967 * Machine expend effort toward recycling unused objects in order to
968 * make the memory they currently occupy available for quick reuse.
969 * When control returns from the method call, the Java Virtual
970 * Machine has made a best effort to reclaim space from all discarded
971 * objects.
972 * <p>
973 * The call <code>System.gc()</code> is effectively equivalent to the
974 * call:
975 * <blockquote><pre>
976 * Runtime.getRuntime().gc()
977 * </pre></blockquote>
978 *
979 * @see java.lang.Runtime#gc()
980 */
981 public static void gc() {
982 Runtime.getRuntime().gc();
983 }
984
985 /**
986 * Runs the finalization methods of any objects pending finalization.
987 * <p>
988 * Calling this method suggests that the Java Virtual Machine expend
989 * effort toward running the <code>finalize</code> methods of objects
990 * that have been found to be discarded but whose <code>finalize</code>
991 * methods have not yet been run. When control returns from the
992 * method call, the Java Virtual Machine has made a best effort to
993 * complete all outstanding finalizations.
994 * <p>
995 * The call <code>System.runFinalization()</code> is effectively
996 * equivalent to the call:
997 * <blockquote><pre>
998 * Runtime.getRuntime().runFinalization()
999 * </pre></blockquote>
1000 *
1001 * @see java.lang.Runtime#runFinalization()
1002 */
1003 public static void runFinalization() {
1004 Runtime.getRuntime().runFinalization();
1005 }
1006
1007 /**
1008 * Enable or disable finalization on exit; doing so specifies that the
1009 * finalizers of all objects that have finalizers that have not yet been
1010 * automatically invoked are to be run before the Java runtime exits.
1011 * By default, finalization on exit is disabled.
1012 *
1013 * <p>If there is a security manager,
1014 * its <code>checkExit</code> method is first called
1015 * with 0 as its argument to ensure the exit is allowed.
1016 * This could result in a SecurityException.
1017 *
1018 * @deprecated This method is inherently unsafe. It may result in
1019 * finalizers being called on live objects while other threads are
1020 * concurrently manipulating those objects, resulting in erratic
1021 * behavior or deadlock.
1022 * @param value indicating enabling or disabling of finalization
1023 * @throws SecurityException
1024 * if a security manager exists and its <code>checkExit</code>
1025 * method doesn't allow the exit.
1026 *
1027 * @see java.lang.Runtime#exit(int)
1028 * @see java.lang.Runtime#gc()
1029 * @see java.lang.SecurityManager#checkExit(int)
1030 * @since 1.1
1031 */
1032 @Deprecated
1033 public static void runFinalizersOnExit(boolean value) {
1034 Runtime.runFinalizersOnExit(value);
1035 }
1036
1037 /**
1038 * Loads the native library specified by the filename argument. The filename
1039 * argument must be an absolute path name.
1040 *
1041 * If the filename argument, when stripped of any platform-specific library
1042 * prefix, path, and file extension, indicates a library whose name is,
1043 * for example, L, and a native library called L is statically linked
1044 * with the VM, then the JNI_OnLoad_L function exported by the library
1045 * is invoked rather than attempting to load a dynamic library.
1046 * A filename matching the argument does not have to exist in the
1047 * file system.
1048 * See the JNI Specification for more details.
1049 *
1050 * Otherwise, the filename argument is mapped to a native library image in
1051 * an implementation-dependent manner.
1052 *
1053 * <p>
1054 * The call <code>System.load(name)</code> is effectively equivalent
1055 * to the call:
1056 * <blockquote><pre>
1057 * Runtime.getRuntime().load(name)
1058 * </pre></blockquote>
1059 *
1060 * @param filename the file to load.
1061 * @exception SecurityException if a security manager exists and its
1062 * <code>checkLink</code> method doesn't allow
1063 * loading of the specified dynamic library
1064 * @exception UnsatisfiedLinkError if either the filename is not an
1065 * absolute path name, the native library is not statically
1066 * linked with the VM, or the library cannot be mapped to
1067 * a native library image by the host system.
1068 * @exception NullPointerException if <code>filename</code> is
1069 * <code>null</code>
1070 * @see java.lang.Runtime#load(java.lang.String)
1071 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1072 */
1073 @CallerSensitive
1074 public static void load(String filename) {
1075 Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
1076 }
1077
1078 /**
1079 * Loads the native library specified by the <code>libname</code>
1080 * argument. The <code>libname</code> argument must not contain any platform
1081 * specific prefix, file extension or path. If a native library
1082 * called <code>libname</code> is statically linked with the VM, then the
1083 * JNI_OnLoad_<code>libname</code> function exported by the library is invoked.
1084 * See the JNI Specification for more details.
1085 *
1086 * Otherwise, the libname argument is loaded from a system library
1087 * location and mapped to a native library image in an implementation-
1088 * dependent manner.
1089 * <p>
1090 * The call <code>System.loadLibrary(name)</code> is effectively
1091 * equivalent to the call
1092 * <blockquote><pre>
1093 * Runtime.getRuntime().loadLibrary(name)
1094 * </pre></blockquote>
1095 *
1096 * @param libname the name of the library.
1097 * @exception SecurityException if a security manager exists and its
1098 * <code>checkLink</code> method doesn't allow
1099 * loading of the specified dynamic library
1100 * @exception UnsatisfiedLinkError if either the libname argument
1101 * contains a file path, the native library is not statically
1102 * linked with the VM, or the library cannot be mapped to a
1103 * native library image by the host system.
1104 * @exception NullPointerException if <code>libname</code> is
1105 * <code>null</code>
1106 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1107 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1108 */
1109 @CallerSensitive
1110 public static void loadLibrary(String libname) {
1111 Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
1112 }
1113
1114 /**
1115 * Maps a library name into a platform-specific string representing
1116 * a native library.
1117 *
1118 * @param libname the name of the library.
1119 * @return a platform-dependent native library name.
1120 * @exception NullPointerException if <code>libname</code> is
1121 * <code>null</code>
1122 * @see java.lang.System#loadLibrary(java.lang.String)
1123 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1124 * @since 1.2
1125 */
1126 public static native String mapLibraryName(String libname);
1127
1128 /**
1129 * Create PrintStream for stdout/err based on encoding.
1130 */
1131 private static PrintStream newPrintStream(FileOutputStream fos, String enc) {
1132 if (enc != null) {
1133 try {
1134 return new PrintStream(new BufferedOutputStream(fos, 128), true, enc);
1135 } catch (UnsupportedEncodingException uee) {}
1136 }
1137 return new PrintStream(new BufferedOutputStream(fos, 128), true);
1138 }
1139
1140
1141 /**
1142 * Initialize the system class. Called after thread initialization.
1143 */
1144 private static void initializeSystemClass() {
1145
1146 // VM might invoke JNU_NewStringPlatform() to set those encoding
1147 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1148 // during "props" initialization, in which it may need access, via
1149 // System.getProperty(), to the related system encoding property that
1150 // have been initialized (put into "props") at early stage of the
1151 // initialization. So make sure the "props" is available at the
1152 // very beginning of the initialization and all system properties to
1153 // be put into it directly.
1154 props = new Properties();
1155 initProperties(props); // initialized by the VM
1156
1157 // There are certain system configurations that may be controlled by
1158 // VM options such as the maximum amount of direct memory and
1159 // Integer cache size used to support the object identity semantics
1160 // of autoboxing. Typically, the library will obtain these values
1161 // from the properties set by the VM. If the properties are for
1162 // internal implementation use only, these properties should be
1163 // removed from the system properties.
1164 //
1165 // See java.lang.Integer.IntegerCache and the
1166 // sun.misc.VM.saveAndRemoveProperties method for example.
1167 //
1168 // Save a private copy of the system properties object that
1169 // can only be accessed by the internal implementation. Remove
1170 // certain system properties that are not intended for public access.
1171 sun.misc.VM.saveAndRemoveProperties(props);
1172
1173
1174 lineSeparator = props.getProperty("line.separator");
1175 sun.misc.Version.init();
1176
1177 FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
1178 FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
1179 FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
1180 setIn0(new BufferedInputStream(fdIn));
1181 setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")));
1182 setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding")));
1183
1184 // Load the zip library now in order to keep java.util.zip.ZipFile
1185 // from trying to use itself to load this library later.
1186 loadLibrary("zip");
1187
1188 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1189 Terminator.setup();
1190
1191 // Initialize any miscellaneous operating system settings that need to be
1192 // set for the class libraries. Currently this is no-op everywhere except
1193 // for Windows where the process-wide error mode is set before the java.io
1194 // classes are used.
1195 sun.misc.VM.initializeOSEnvironment();
1196
1197 // The main thread is not added to its thread group in the same
1198 // way as other threads; we must do it ourselves here.
1199 Thread current = Thread.currentThread();
1200 current.getThreadGroup().add(current);
1201
1202 // register shared secrets
1203 setJavaLangAccess();
1204
1205 // Subsystems that are invoked during initialization can invoke
1206 // sun.misc.VM.isBooted() in order to avoid doing things that should
1207 // wait until the application class loader has been set up.
1208 // IMPORTANT: Ensure that this remains the last initialization action!
1209 sun.misc.VM.booted();
1210 }
1211
1212 private static void setJavaLangAccess() {
1213 // Allow privileged classes outside of java.lang
1214 sun.misc.SharedSecrets.setJavaLangAccess(new sun.misc.JavaLangAccess(){
1215 public sun.reflect.ConstantPool getConstantPool(Class<?> klass) {
1216 return klass.getConstantPool();
1217 }
1218 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
1219 return klass.casAnnotationType(oldType, newType);
1220 }
1221 public AnnotationType getAnnotationType(Class<?> klass) {
1222 return klass.getAnnotationType();
1223 }
1224 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
1225 return klass.getDeclaredAnnotationMap();
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 public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) {
1256 return new Thread(target, acc);
1257 }
1258 public void invokeFinalize(Object o) throws Throwable {
1259 o.finalize();
1260 }
1261 public void formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
1262 Long.formatUnsignedLong(val, shift, buf, offset, len);
1263 }
1264 public void formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
1265 Integer.formatUnsignedInt(val, shift, buf, offset, len);
1266 }
1267 });
1268 }
1269 }