1 /*
2 * Copyright (c) 1994, 2025, 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.BufferedInputStream;
28 import java.io.BufferedOutputStream;
29 import java.io.Console;
30 import java.io.FileDescriptor;
31 import java.io.FileInputStream;
32 import java.io.FileOutputStream;
33 import java.io.IOException;
34 import java.io.InputStream;
35 import java.io.OutputStream;
36 import java.io.PrintStream;
37 import java.lang.annotation.Annotation;
38 import java.lang.foreign.MemorySegment;
39 import java.lang.invoke.MethodHandle;
40 import java.lang.invoke.MethodType;
41 import java.lang.module.ModuleDescriptor;
42 import java.lang.reflect.Executable;
43 import java.lang.reflect.Method;
44 import java.net.URI;
45 import java.nio.channels.Channel;
46 import java.nio.channels.spi.SelectorProvider;
47 import java.nio.charset.CharacterCodingException;
48 import java.nio.charset.Charset;
49 import java.security.ProtectionDomain;
50 import java.util.List;
51 import java.util.Locale;
52 import java.util.Map;
53 import java.util.Objects;
54 import java.util.Properties;
55 import java.util.ResourceBundle;
56 import java.util.Set;
57 import java.util.concurrent.Executor;
58 import java.util.concurrent.ScheduledExecutorService;
59 import java.util.function.Supplier;
60 import java.util.concurrent.ConcurrentHashMap;
61 import java.util.stream.Stream;
62
63 import jdk.internal.javac.Restricted;
64 import jdk.internal.loader.NativeLibraries;
65 import jdk.internal.logger.LoggerFinderLoader.TemporaryLoggerFinder;
66 import jdk.internal.misc.Blocker;
67 import jdk.internal.misc.CarrierThreadLocal;
68 import jdk.internal.util.StaticProperty;
69 import jdk.internal.module.ModuleBootstrap;
70 import jdk.internal.module.ServicesCatalog;
71 import jdk.internal.reflect.CallerSensitive;
72 import jdk.internal.reflect.Reflection;
73 import jdk.internal.access.JavaLangAccess;
74 import jdk.internal.access.SharedSecrets;
75 import jdk.internal.logger.LoggerFinderLoader;
76 import jdk.internal.logger.LazyLoggers;
77 import jdk.internal.logger.LocalizedLoggerWrapper;
78 import jdk.internal.misc.VM;
79 import jdk.internal.util.SystemProps;
80 import jdk.internal.vm.Continuation;
81 import jdk.internal.vm.ContinuationScope;
82 import jdk.internal.vm.StackableScope;
83 import jdk.internal.vm.ThreadContainer;
84 import jdk.internal.vm.annotation.IntrinsicCandidate;
85 import jdk.internal.vm.annotation.Stable;
86 import sun.reflect.annotation.AnnotationType;
87 import sun.nio.ch.Interruptible;
88 import sun.nio.cs.UTF_8;
89
90 /**
91 * The {@code System} class contains several useful class fields
92 * and methods. It cannot be instantiated.
93 *
94 * Among the facilities provided by the {@code System} class
95 * are standard input, standard output, and error output streams;
96 * access to externally defined properties and environment
97 * variables; a means of loading files and libraries; and a utility
98 * method for quickly copying a portion of an array.
99 *
100 * @since 1.0
101 */
102 public final class System {
103 /* Register the natives via the static initializer.
104 *
105 * The VM will invoke the initPhase1 method to complete the initialization
106 * of this class separate from <clinit>.
107 */
108 private static native void registerNatives();
109 static {
110 registerNatives();
111 }
112
113 /** Don't let anyone instantiate this class */
114 private System() {
115 }
116
117 /**
118 * The "standard" input stream. This stream is already
119 * open and ready to supply input data. This stream
120 * corresponds to keyboard input or another input source specified by
121 * the host environment or user. Applications should use the encoding
122 * specified by the {@link ##stdin.encoding stdin.encoding} property
123 * to convert input bytes to character data.
124 *
125 * @apiNote
126 * The typical approach to read character data is to wrap {@code System.in}
127 * within an {@link java.io.InputStreamReader InputStreamReader} or other object
128 * that handles character encoding. After this is done, subsequent reading should
129 * use only the wrapper object; operating directly on {@code System.in} results
130 * in unspecified behavior.
131 * <p>
132 * For handling interactive input, consider using {@link Console}.
133 *
134 * @see Console
135 * @see ##stdin.encoding stdin.encoding
136 */
137 public static final InputStream in = null;
138
139 /**
140 * The "standard" output stream. This stream is already
141 * open and ready to accept output data. Typically this stream
142 * corresponds to display output or another output destination
143 * specified by the host environment or user. The encoding used
144 * in the conversion from characters to bytes is equivalent to
145 * {@link ##stdout.encoding stdout.encoding}.
146 * <p>
147 * For simple stand-alone Java applications, a typical way to write
148 * a line of output data is:
149 * <blockquote><pre>
150 * System.out.println(data)
151 * </pre></blockquote>
152 * <p>
153 * See the {@code println} methods in class {@code PrintStream}.
154 *
155 * @see java.io.PrintStream#println()
156 * @see java.io.PrintStream#println(boolean)
157 * @see java.io.PrintStream#println(char)
158 * @see java.io.PrintStream#println(char[])
159 * @see java.io.PrintStream#println(double)
160 * @see java.io.PrintStream#println(float)
161 * @see java.io.PrintStream#println(int)
162 * @see java.io.PrintStream#println(long)
163 * @see java.io.PrintStream#println(java.lang.Object)
164 * @see java.io.PrintStream#println(java.lang.String)
165 * @see ##stdout.encoding stdout.encoding
166 */
167 public static final PrintStream out = null;
168
169 /**
170 * The "standard" error output stream. This stream is already
171 * open and ready to accept output data.
172 * <p>
173 * Typically this stream corresponds to display output or another
174 * output destination specified by the host environment or user. By
175 * convention, this output stream is used to display error messages
176 * or other information that should come to the immediate attention
177 * of a user even if the principal output stream, the value of the
178 * variable {@code out}, has been redirected to a file or other
179 * destination that is typically not continuously monitored.
180 * The encoding used in the conversion from characters to bytes is
181 * equivalent to {@link ##stderr.encoding stderr.encoding}.
182 *
183 * @see ##stderr.encoding stderr.encoding
184 */
185 public static final PrintStream err = null;
186
187 // Initial values of System.in and System.err, set in initPhase1().
188 private static @Stable InputStream initialIn;
189 private static @Stable PrintStream initialErr;
190
191 // `sun.jnu.encoding` if it is not supported. Otherwise null.
192 // It is initialized in `initPhase1()` before any charset providers
193 // are initialized.
194 private static String notSupportedJnuEncoding;
195
196 /**
197 * Reassigns the "standard" input stream.
198 *
199 * @param in the new standard input stream.
200 *
201 * @since 1.1
202 */
203 public static void setIn(InputStream in) {
204 setIn0(in);
205 }
206
207 /**
208 * Reassigns the "standard" output stream.
209 *
210 * @param out the new standard output stream
211 *
212 * @since 1.1
213 */
214 public static void setOut(PrintStream out) {
215 setOut0(out);
216 }
217
218 /**
219 * Reassigns the "standard" error output stream.
220 *
221 * @param err the new standard error output stream.
222 *
223 * @since 1.1
224 */
225 public static void setErr(PrintStream err) {
226 setErr0(err);
227 }
228
229 private static volatile Console cons;
230
231 /**
232 * Returns the unique {@link java.io.Console Console} object associated
233 * with the current Java virtual machine, if any.
234 *
235 * @return The system console, if any, otherwise {@code null}.
236 *
237 * @since 1.6
238 */
239 public static Console console() {
240 Console c;
241 if ((c = cons) == null) {
242 synchronized (System.class) {
243 if ((c = cons) == null) {
244 cons = c = SharedSecrets.getJavaIOAccess().console();
245 }
246 }
247 }
248 return c;
249 }
250
251 /**
252 * Returns the channel inherited from the entity that created this
253 * Java virtual machine.
254 *
255 * This method returns the channel obtained by invoking the
256 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
257 * inheritedChannel} method of the system-wide default
258 * {@link java.nio.channels.spi.SelectorProvider} object.
259 *
260 * <p> In addition to the network-oriented channels described in
261 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
262 * inheritedChannel}, this method may return other kinds of
263 * channels in the future.
264 *
265 * @return The inherited channel, if any, otherwise {@code null}.
266 *
267 * @throws IOException
268 * If an I/O error occurs
269 *
270 * @since 1.5
271 */
272 public static Channel inheritedChannel() throws IOException {
273 return SelectorProvider.provider().inheritedChannel();
274 }
275
276 private static native void setIn0(InputStream in);
277 private static native void setOut0(PrintStream out);
278 private static native void setErr0(PrintStream err);
279
280 /**
281 * Throws {@code UnsupportedOperationException}. Setting a security manager
282 * is not supported.
283 *
284 * @param sm ignored
285 * @throws UnsupportedOperationException always
286 * @see #getSecurityManager
287 * @deprecated This method originally set
288 * {@linkplain SecurityManager the system-wide Security Manager}.
289 * Setting a Security Manager is no longer supported. There is no
290 * replacement for the Security Manager or this method.
291 */
292 @Deprecated(since="17", forRemoval=true)
293 public static void setSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
294 throw new UnsupportedOperationException(
295 "Setting a Security Manager is not supported");
296 }
297
298 /**
299 * Returns {@code null}. Setting a security manager is not supported.
300 *
301 * @return {@code null}
302 * @see #setSecurityManager
303 * @deprecated This method originally returned
304 * {@linkplain SecurityManager the system-wide Security Manager}.
305 * Setting a Security Manager is no longer supported. There is no
306 * replacement for the Security Manager or this method.
307 */
308 @SuppressWarnings("removal")
309 @Deprecated(since="17", forRemoval=true)
310 public static SecurityManager getSecurityManager() {
311 return null;
312 }
313
314 /**
315 * Returns the current time in milliseconds. Note that
316 * while the unit of time of the return value is a millisecond,
317 * the granularity of the value depends on the underlying
318 * operating system and may be larger. For example, many
319 * operating systems measure time in units of tens of
320 * milliseconds.
321 *
322 * <p> See the description of the class {@code Date} for
323 * a discussion of slight discrepancies that may arise between
324 * "computer time" and coordinated universal time (UTC).
325 *
326 * @return the difference, measured in milliseconds, between
327 * the current time and midnight, January 1, 1970 UTC.
328 * @see java.util.Date
329 */
330 @IntrinsicCandidate
331 public static native long currentTimeMillis();
332
333 /**
334 * Returns the current value of the running Java Virtual Machine's
335 * high-resolution time source, in nanoseconds.
336 *
337 * This method can only be used to measure elapsed time and is
338 * not related to any other notion of system or wall-clock time.
339 * The value returned represents nanoseconds since some fixed but
340 * arbitrary <i>origin</i> time (perhaps in the future, so values
341 * may be negative). The same origin is used by all invocations of
342 * this method in an instance of a Java virtual machine; other
343 * virtual machine instances are likely to use a different origin.
344 *
345 * <p>This method provides nanosecond precision, but not necessarily
346 * nanosecond resolution (that is, how frequently the value changes)
347 * - no guarantees are made except that the resolution is at least as
348 * good as that of {@link #currentTimeMillis()}.
349 *
350 * <p>Differences in successive calls that span greater than
351 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
352 * correctly compute elapsed time due to numerical overflow.
353 *
354 * <p>The values returned by this method become meaningful only when
355 * the difference between two such values, obtained within the same
356 * instance of a Java virtual machine, is computed.
357 *
358 * <p>For example, to measure how long some code takes to execute:
359 * <pre> {@code
360 * long startTime = System.nanoTime();
361 * // ... the code being measured ...
362 * long elapsedNanos = System.nanoTime() - startTime;}</pre>
363 *
364 * <p>To compare elapsed time against a timeout, use <pre> {@code
365 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
366 * instead of <pre> {@code
367 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
368 * because of the possibility of numerical overflow.
369 *
370 * @return the current value of the running Java Virtual Machine's
371 * high-resolution time source, in nanoseconds
372 * @since 1.5
373 */
374 @IntrinsicCandidate
375 public static native long nanoTime();
376
377 /**
378 * Copies an array from the specified source array, beginning at the
379 * specified position, to the specified position of the destination array.
380 * A subsequence of array components are copied from the source
381 * array referenced by {@code src} to the destination array
382 * referenced by {@code dest}. The number of components copied is
383 * equal to the {@code length} argument. The components at
384 * positions {@code srcPos} through
385 * {@code srcPos+length-1} in the source array are copied into
386 * positions {@code destPos} through
387 * {@code destPos+length-1}, respectively, of the destination
388 * array.
389 * <p>
390 * If the {@code src} and {@code dest} arguments refer to the
391 * same array object, then the copying is performed as if the
392 * components at positions {@code srcPos} through
393 * {@code srcPos+length-1} were first copied to a temporary
394 * array with {@code length} components and then the contents of
395 * the temporary array were copied into positions
396 * {@code destPos} through {@code destPos+length-1} of the
397 * destination array.
398 * <p>
399 * If {@code dest} is {@code null}, then a
400 * {@code NullPointerException} is thrown.
401 * <p>
402 * If {@code src} is {@code null}, then a
403 * {@code NullPointerException} is thrown and the destination
404 * array is not modified.
405 * <p>
406 * Otherwise, if any of the following is true, an
407 * {@code ArrayStoreException} is thrown and the destination is
408 * not modified:
409 * <ul>
410 * <li>The {@code src} argument refers to an object that is not an
411 * array.
412 * <li>The {@code dest} argument refers to an object that is not an
413 * array.
414 * <li>The {@code src} argument and {@code dest} argument refer
415 * to arrays whose component types are different primitive types.
416 * <li>The {@code src} argument refers to an array with a primitive
417 * component type and the {@code dest} argument refers to an array
418 * with a reference component type.
419 * <li>The {@code src} argument refers to an array with a reference
420 * component type and the {@code dest} argument refers to an array
421 * with a primitive component type.
422 * </ul>
423 * <p>
424 * Otherwise, if any of the following is true, an
425 * {@code IndexOutOfBoundsException} is
426 * thrown and the destination is not modified:
427 * <ul>
428 * <li>The {@code srcPos} argument is negative.
429 * <li>The {@code destPos} argument is negative.
430 * <li>The {@code length} argument is negative.
431 * <li>{@code srcPos+length} is greater than
432 * {@code src.length}, the length of the source array.
433 * <li>{@code destPos+length} is greater than
434 * {@code dest.length}, the length of the destination array.
435 * </ul>
436 * <p>
437 * Otherwise, if any actual component of the source array from
438 * position {@code srcPos} through
439 * {@code srcPos+length-1} cannot be converted to the component
440 * type of the destination array by assignment conversion, an
441 * {@code ArrayStoreException} is thrown. In this case, let
442 * <b><i>k</i></b> be the smallest nonnegative integer less than
443 * length such that {@code src[srcPos+}<i>k</i>{@code ]}
444 * cannot be converted to the component type of the destination
445 * array; when the exception is thrown, source array components from
446 * positions {@code srcPos} through
447 * {@code srcPos+}<i>k</i>{@code -1}
448 * will already have been copied to destination array positions
449 * {@code destPos} through
450 * {@code destPos+}<i>k</I>{@code -1} and no other
451 * positions of the destination array will have been modified.
452 * (Because of the restrictions already itemized, this
453 * paragraph effectively applies only to the situation where both
454 * arrays have component types that are reference types.)
455 *
456 * @param src the source array.
457 * @param srcPos starting position in the source array.
458 * @param dest the destination array.
459 * @param destPos starting position in the destination data.
460 * @param length the number of array elements to be copied.
461 * @throws IndexOutOfBoundsException if copying would cause
462 * access of data outside array bounds.
463 * @throws ArrayStoreException if an element in the {@code src}
464 * array could not be stored into the {@code dest} array
465 * because of a type mismatch.
466 * @throws NullPointerException if either {@code src} or
467 * {@code dest} is {@code null}.
468 */
469 @IntrinsicCandidate
470 public static native void arraycopy(Object src, int srcPos,
471 Object dest, int destPos,
472 int length);
473
474 /**
475 * Returns the same hash code for the given object as
476 * would be returned by the default method hashCode(),
477 * whether or not the given object's class overrides
478 * hashCode().
479 * The hash code for the null reference is zero.
480 *
481 * @param x object for which the hashCode is to be calculated
482 * @return the hashCode
483 * @since 1.1
484 * @see Object#hashCode
485 * @see java.util.Objects#hashCode(Object)
486 */
487 @IntrinsicCandidate
488 public static native int identityHashCode(Object x);
489
490 /**
491 * System properties.
492 *
493 * See {@linkplain #getProperties getProperties} for details.
494 */
495 private static Properties props;
496
497 /**
498 * Determines the current system properties.
499 * <p>
500 * The current set of system properties for use by the
501 * {@link #getProperty(String)} method is returned as a
502 * {@code Properties} object. If there is no current set of
503 * system properties, a set of system properties is first created and
504 * initialized. This set of system properties includes a value
505 * for each of the following keys unless the description of the associated
506 * value indicates that the value is optional.
507 * <table class="striped" style="text-align:left">
508 * <caption style="display:none">Shows property keys and associated values</caption>
509 * <thead>
510 * <tr><th scope="col">Key</th>
511 * <th scope="col">Description of Associated Value</th></tr>
512 * </thead>
513 * <tbody>
514 * <tr><th scope="row">{@systemProperty java.version}</th>
515 * <td>Java Runtime Environment version, which may be interpreted
516 * as a {@link Runtime.Version}</td></tr>
517 * <tr><th scope="row">{@systemProperty java.version.date}</th>
518 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
519 * format, which may be interpreted as a {@link
520 * java.time.LocalDate}</td></tr>
521 * <tr><th scope="row">{@systemProperty java.vendor}</th>
522 * <td>Java Runtime Environment vendor</td></tr>
523 * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
524 * <td>Java vendor URL</td></tr>
525 * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
526 * <td>Java vendor version <em>(optional)</em> </td></tr>
527 * <tr><th scope="row">{@systemProperty java.home}</th>
528 * <td>Java installation directory</td></tr>
529 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
530 * <td>Java Virtual Machine specification version, whose value is the
531 * {@linkplain Runtime.Version#feature feature} element of the
532 * {@linkplain Runtime#version() runtime version}</td></tr>
533 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
534 * <td>Java Virtual Machine specification vendor</td></tr>
535 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
536 * <td>Java Virtual Machine specification name</td></tr>
537 * <tr><th scope="row">{@systemProperty java.vm.version}</th>
538 * <td>Java Virtual Machine implementation version which may be
539 * interpreted as a {@link Runtime.Version}</td></tr>
540 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
541 * <td>Java Virtual Machine implementation vendor</td></tr>
542 * <tr><th scope="row">{@systemProperty java.vm.name}</th>
543 * <td>Java Virtual Machine implementation name</td></tr>
544 * <tr><th scope="row">{@systemProperty java.specification.version}</th>
545 * <td>Java Runtime Environment specification version, whose value is
546 * the {@linkplain Runtime.Version#feature feature} element of the
547 * {@linkplain Runtime#version() runtime version}</td></tr>
548 * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
549 * <td>Java Runtime Environment specification maintenance version,
550 * may be interpreted as a positive integer <em>(optional, see below)</em></td></tr>
551 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
552 * <td>Java Runtime Environment specification vendor</td></tr>
553 * <tr><th scope="row">{@systemProperty java.specification.name}</th>
554 * <td>Java Runtime Environment specification name</td></tr>
555 * <tr><th scope="row">{@systemProperty java.class.version}</th>
556 * <td>{@linkplain java.lang.reflect.ClassFileFormatVersion#latest() Latest}
557 * Java class file format version recognized by the Java runtime as {@code "MAJOR.MINOR"}
558 * where {@link java.lang.reflect.ClassFileFormatVersion#major() MAJOR} and {@code MINOR}
559 * are both formatted as decimal integers</td></tr>
560 * <tr><th scope="row">{@systemProperty java.class.path}</th>
561 * <td>Java class path (refer to
562 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
563 * <tr><th scope="row">{@systemProperty java.library.path}</th>
564 * <td>List of paths to search when loading libraries</td></tr>
565 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
566 * <td>Default temp file path</td></tr>
567 * <tr><th scope="row">{@systemProperty os.name}</th>
568 * <td>Operating system name</td></tr>
569 * <tr><th scope="row">{@systemProperty os.arch}</th>
570 * <td>Operating system architecture</td></tr>
571 * <tr><th scope="row">{@systemProperty os.version}</th>
572 * <td>Operating system version</td></tr>
573 * <tr><th scope="row">{@systemProperty file.separator}</th>
574 * <td>File separator ("/" on UNIX)</td></tr>
575 * <tr><th scope="row">{@systemProperty path.separator}</th>
576 * <td>Path separator (":" on UNIX)</td></tr>
577 * <tr><th scope="row">{@systemProperty line.separator}</th>
578 * <td>Line separator ("\n" on UNIX)</td></tr>
579 * <tr><th scope="row">{@systemProperty user.name}</th>
580 * <td>User's account name</td></tr>
581 * <tr><th scope="row">{@systemProperty user.home}</th>
582 * <td>User's home directory</td></tr>
583 * <tr><th scope="row">{@systemProperty user.dir}</th>
584 * <td>User's current working directory</td></tr>
585 * <tr><th scope="row">{@systemProperty native.encoding}</th>
586 * <td>Character encoding name derived from the host environment and
587 * the user's settings. Setting this system property on the command line
588 * has no effect.</td></tr>
589 * <tr><th scope="row">{@systemProperty stdin.encoding}</th>
590 * <td>Character encoding name for {@link System#in System.in}.
591 * The Java runtime can be started with the system property set to {@code UTF-8}.
592 * Starting it with the property set to another value results in unspecified behavior.
593 * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
594 * <td>Character encoding name for {@link System#out System.out} and
595 * {@link System#console() System.console()}.
596 * The Java runtime can be started with the system property set to {@code UTF-8}.
597 * Starting it with the property set to another value results in unspecified behavior.
598 * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
599 * <td>Character encoding name for {@link System#err System.err}.
600 * The Java runtime can be started with the system property set to {@code UTF-8}.
601 * Starting it with the property set to another value results in unspecified behavior.
602 * </tbody>
603 * </table>
604 * <p>
605 * The {@code java.specification.maintenance.version} property is
606 * defined if the specification implemented by this runtime at the
607 * time of its construction had undergone a <a
608 * href="https://jcp.org/en/procedures/jcp2#3.6.4">maintenance
609 * release</a>. When defined, its value identifies that
610 * maintenance release. To indicate the first maintenance release
611 * this property will have the value {@code "1"}, to indicate the
612 * second maintenance release this property will have the value
613 * {@code "2"}, and so on.
614 * <p>
615 * Multiple paths in a system property value are separated by the path
616 * separator character of the platform.
617 * <p>
618 * Additional locale-related system properties defined by the
619 * {@link Locale##default_locale Default Locale} section in the {@code Locale}
620 * class description may also be obtained with this method.
621 *
622 * @apiNote
623 * <strong>Changing a standard system property may have unpredictable results
624 * unless otherwise specified.</strong>
625 * Property values may be cached during initialization or on first use.
626 * Setting a standard property after initialization using {@link #getProperties()},
627 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
628 * {@link #clearProperty(String)} may not have the desired effect.
629 *
630 * @implNote
631 * In addition to the standard system properties, the system
632 * properties may include the following keys:
633 * <table class="striped">
634 * <caption style="display:none">Shows property keys and associated values</caption>
635 * <thead>
636 * <tr><th scope="col">Key</th>
637 * <th scope="col">Description of Associated Value</th></tr>
638 * </thead>
639 * <tbody>
640 * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
641 * <td>The application module path</td></tr>
642 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
643 * <td>The upgrade module path</td></tr>
644 * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
645 * <td>The module name of the initial/main module</td></tr>
646 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
647 * <td>The main class name of the initial module</td></tr>
648 * <tr><th scope="row">{@systemProperty file.encoding}</th>
649 * <td>The name of the default charset, defaults to {@code UTF-8}.
650 * The property may be set on the command line to the value
651 * {@code UTF-8} or {@code COMPAT}. If set on the command line to
652 * the value {@code COMPAT} then the value is replaced with the
653 * value of the {@code native.encoding} property during startup.
654 * Setting the property to a value other than {@code UTF-8} or
655 * {@code COMPAT} results in unspecified behavior.
656 * </td></tr>
657 * </tbody>
658 * </table>
659 *
660 * @return the system properties
661 * @see #setProperties
662 * @see java.util.Properties
663 */
664 public static Properties getProperties() {
665 return props;
666 }
667
668 /**
669 * Returns the system-dependent line separator string. It always
670 * returns the same value - the initial value of the {@linkplain
671 * #getProperty(String) system property} {@code line.separator}.
672 *
673 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
674 * Windows systems it returns {@code "\r\n"}.
675 *
676 * @return the system-dependent line separator string
677 * @since 1.7
678 */
679 public static String lineSeparator() {
680 return lineSeparator;
681 }
682
683 private static String lineSeparator;
684
685 /**
686 * Sets the system properties to the {@code Properties} argument.
687 * <p>
688 * The argument becomes the current set of system properties for use
689 * by the {@link #getProperty(String)} method. If the argument is
690 * {@code null}, then the current set of system properties is
691 * forgotten.
692 *
693 * @apiNote
694 * <strong>Changing a standard system property may have unpredictable results
695 * unless otherwise specified</strong>.
696 * See {@linkplain #getProperties getProperties} for details.
697 *
698 * @param props the new system properties.
699 * @see #getProperties
700 * @see java.util.Properties
701 */
702 public static void setProperties(Properties props) {
703 if (props == null) {
704 Map<String, String> tempProps = SystemProps.initProperties();
705 VersionProps.init(tempProps);
706 props = createProperties(tempProps);
707 }
708 System.props = props;
709 }
710
711 /**
712 * Gets the system property indicated by the specified key.
713 * <p>
714 * If there is no current set of system properties, a set of system
715 * properties is first created and initialized in the same manner as
716 * for the {@code getProperties} method.
717 *
718 * @apiNote
719 * <strong>Changing a standard system property may have unpredictable results
720 * unless otherwise specified</strong>.
721 * See {@linkplain #getProperties getProperties} for details.
722 *
723 * @param key the name of the system property.
724 * @return the string value of the system property,
725 * or {@code null} if there is no property with that key.
726 *
727 * @throws NullPointerException if {@code key} is {@code null}.
728 * @throws IllegalArgumentException if {@code key} is empty.
729 * @see #setProperty
730 * @see java.lang.System#getProperties()
731 */
732 public static String getProperty(String key) {
733 checkKey(key);
734 return props.getProperty(key);
735 }
736
737 /**
738 * Gets the system property indicated by the specified key.
739 * <p>
740 * If there is no current set of system properties, a set of system
741 * properties is first created and initialized in the same manner as
742 * for the {@code getProperties} method.
743 *
744 * @param key the name of the system property.
745 * @param def a default value.
746 * @return the string value of the system property,
747 * or the default value if there is no property with that key.
748 *
749 * @throws NullPointerException if {@code key} is {@code null}.
750 * @throws IllegalArgumentException if {@code key} is empty.
751 * @see #setProperty
752 * @see java.lang.System#getProperties()
753 */
754 public static String getProperty(String key, String def) {
755 checkKey(key);
756 return props.getProperty(key, def);
757 }
758
759 /**
760 * Sets the system property indicated by the specified key.
761 *
762 * @apiNote
763 * <strong>Changing a standard system property may have unpredictable results
764 * unless otherwise specified</strong>.
765 * See {@linkplain #getProperties getProperties} for details.
766 *
767 * @param key the name of the system property.
768 * @param value the value of the system property.
769 * @return the previous value of the system property,
770 * or {@code null} if it did not have one.
771 *
772 * @throws NullPointerException if {@code key} or
773 * {@code value} is {@code null}.
774 * @throws IllegalArgumentException if {@code key} is empty.
775 * @see #getProperty
776 * @see java.lang.System#getProperty(java.lang.String)
777 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
778 * @since 1.2
779 */
780 public static String setProperty(String key, String value) {
781 checkKey(key);
782 return (String) props.setProperty(key, value);
783 }
784
785 /**
786 * Removes the system property indicated by the specified key.
787 *
788 * @apiNote
789 * <strong>Changing a standard system property may have unpredictable results
790 * unless otherwise specified</strong>.
791 * See {@linkplain #getProperties getProperties} method for details.
792 *
793 * @param key the name of the system property to be removed.
794 * @return the previous string value of the system property,
795 * or {@code null} if there was no property with that key.
796 *
797 * @throws NullPointerException if {@code key} is {@code null}.
798 * @throws IllegalArgumentException if {@code key} is empty.
799 * @see #getProperty
800 * @see #setProperty
801 * @see java.util.Properties
802 * @since 1.5
803 */
804 public static String clearProperty(String key) {
805 checkKey(key);
806 return (String) props.remove(key);
807 }
808
809 private static void checkKey(String key) {
810 if (key == null) {
811 throw new NullPointerException("key can't be null");
812 }
813 if (key.isEmpty()) {
814 throw new IllegalArgumentException("key can't be empty");
815 }
816 }
817
818 /**
819 * Gets the value of the specified environment variable. An
820 * environment variable is a system-dependent external named
821 * value.
822 *
823 * <p><a id="EnvironmentVSSystemProperties"><i>System
824 * properties</i> and <i>environment variables</i></a> are both
825 * conceptually mappings between names and values. Both
826 * mechanisms can be used to pass user-defined information to a
827 * Java process. Environment variables have a more global effect,
828 * because they are visible to all descendants of the process
829 * which defines them, not just the immediate Java subprocess.
830 * They can have subtly different semantics, such as case
831 * insensitivity, on different operating systems. For these
832 * reasons, environment variables are more likely to have
833 * unintended side effects. It is best to use system properties
834 * where possible. Environment variables should be used when a
835 * global effect is desired, or when an external system interface
836 * requires an environment variable (such as {@code PATH}).
837 *
838 * <p>On UNIX systems the alphabetic case of {@code name} is
839 * typically significant, while on Microsoft Windows systems it is
840 * typically not. For example, the expression
841 * {@code System.getenv("FOO").equals(System.getenv("foo"))}
842 * is likely to be true on Microsoft Windows.
843 *
844 * @param name the name of the environment variable
845 * @return the string value of the variable, or {@code null}
846 * if the variable is not defined in the system environment
847 * @throws NullPointerException if {@code name} is {@code null}
848 * @see #getenv()
849 * @see ProcessBuilder#environment()
850 */
851 public static String getenv(String name) {
852 return ProcessEnvironment.getenv(name);
853 }
854
855
856 /**
857 * Returns an unmodifiable string map view of the current system environment.
858 * The environment is a system-dependent mapping from names to
859 * values which is passed from parent to child processes.
860 *
861 * <p>If the system does not support environment variables, an
862 * empty map is returned.
863 *
864 * <p>The returned map will never contain null keys or values.
865 * Attempting to query the presence of a null key or value will
866 * throw a {@link NullPointerException}. Attempting to query
867 * the presence of a key or value which is not of type
868 * {@link String} will throw a {@link ClassCastException}.
869 *
870 * <p>The returned map and its collection views may not obey the
871 * general contract of the {@link Object#equals} and
872 * {@link Object#hashCode} methods.
873 *
874 * <p>The returned map is typically case-sensitive on all platforms.
875 *
876 * <p>When passing information to a Java subprocess,
877 * <a href=#EnvironmentVSSystemProperties>system properties</a>
878 * are generally preferred over environment variables.
879 *
880 * @return the environment as a map of variable names to values
881 * @see #getenv(String)
882 * @see ProcessBuilder#environment()
883 * @since 1.5
884 */
885 public static java.util.Map<String,String> getenv() {
886 return ProcessEnvironment.getenv();
887 }
888
889 /**
890 * {@code System.Logger} instances log messages that will be
891 * routed to the underlying logging framework the {@link System.LoggerFinder
892 * LoggerFinder} uses.
893 *
894 * {@code System.Logger} instances are typically obtained from
895 * the {@link java.lang.System System} class, by calling
896 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
897 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
898 * System.getLogger(loggerName, bundle)}.
899 *
900 * @see java.lang.System#getLogger(java.lang.String)
901 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
902 * @see java.lang.System.LoggerFinder
903 *
904 * @since 9
905 */
906 public interface Logger {
907
908 /**
909 * System {@linkplain Logger loggers} levels.
910 *
911 * A level has a {@linkplain #getName() name} and {@linkplain
912 * #getSeverity() severity}.
913 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
914 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
915 * by order of increasing severity.
916 * <br>
917 * {@link #ALL} and {@link #OFF}
918 * are simple markers with severities mapped respectively to
919 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
920 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
921 * <p>
922 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
923 * <p>
924 * {@linkplain System.Logger.Level System logger levels} are mapped to
925 * {@linkplain java.logging/java.util.logging.Level java.util.logging levels}
926 * of corresponding severity.
927 * <br>The mapping is as follows:
928 * <br><br>
929 * <table class="striped">
930 * <caption>System.Logger Severity Level Mapping</caption>
931 * <thead>
932 * <tr><th scope="col">System.Logger Levels</th>
933 * <th scope="col">java.util.logging Levels</th>
934 * </thead>
935 * <tbody>
936 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
937 * <td>{@link java.logging/java.util.logging.Level#ALL ALL}</td>
938 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
939 * <td>{@link java.logging/java.util.logging.Level#FINER FINER}</td>
940 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
941 * <td>{@link java.logging/java.util.logging.Level#FINE FINE}</td>
942 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
943 * <td>{@link java.logging/java.util.logging.Level#INFO INFO}</td>
944 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
945 * <td>{@link java.logging/java.util.logging.Level#WARNING WARNING}</td>
946 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
947 * <td>{@link java.logging/java.util.logging.Level#SEVERE SEVERE}</td>
948 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
949 * <td>{@link java.logging/java.util.logging.Level#OFF OFF}</td>
950 * </tbody>
951 * </table>
952 *
953 * @since 9
954 *
955 * @see java.lang.System.LoggerFinder
956 * @see java.lang.System.Logger
957 */
958 @SuppressWarnings("doclint:reference") // cross-module links
959 public enum Level {
960
961 // for convenience, we're reusing java.util.logging.Level int values
962 // the mapping logic in sun.util.logging.PlatformLogger depends
963 // on this.
964 /**
965 * A marker to indicate that all levels are enabled.
966 * This level {@linkplain #getSeverity() severity} is
967 * {@link Integer#MIN_VALUE}.
968 */
969 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
970 /**
971 * {@code TRACE} level: usually used to log diagnostic information.
972 * This level {@linkplain #getSeverity() severity} is
973 * {@code 400}.
974 */
975 TRACE(400), // typically mapped to/from j.u.l.Level.FINER
976 /**
977 * {@code DEBUG} level: usually used to log debug information traces.
978 * This level {@linkplain #getSeverity() severity} is
979 * {@code 500}.
980 */
981 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
982 /**
983 * {@code INFO} level: usually used to log information messages.
984 * This level {@linkplain #getSeverity() severity} is
985 * {@code 800}.
986 */
987 INFO(800), // typically mapped to/from j.u.l.Level.INFO
988 /**
989 * {@code WARNING} level: usually used to log warning messages.
990 * This level {@linkplain #getSeverity() severity} is
991 * {@code 900}.
992 */
993 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
994 /**
995 * {@code ERROR} level: usually used to log error messages.
996 * This level {@linkplain #getSeverity() severity} is
997 * {@code 1000}.
998 */
999 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
1000 /**
1001 * A marker to indicate that all levels are disabled.
1002 * This level {@linkplain #getSeverity() severity} is
1003 * {@link Integer#MAX_VALUE}.
1004 */
1005 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
1006
1007 private final int severity;
1008
1009 private Level(int severity) {
1010 this.severity = severity;
1011 }
1012
1013 /**
1014 * Returns the name of this level.
1015 * @return this level {@linkplain #name()}.
1016 */
1017 public final String getName() {
1018 return name();
1019 }
1020
1021 /**
1022 * Returns the severity of this level.
1023 * A higher severity means a more severe condition.
1024 * @return this level severity.
1025 */
1026 public final int getSeverity() {
1027 return severity;
1028 }
1029 }
1030
1031 /**
1032 * Returns the name of this logger.
1033 *
1034 * @return the logger name.
1035 */
1036 public String getName();
1037
1038 /**
1039 * Checks if a message of the given level would be logged by
1040 * this logger.
1041 *
1042 * @param level the log message level.
1043 * @return {@code true} if the given log message level is currently
1044 * being logged.
1045 *
1046 * @throws NullPointerException if {@code level} is {@code null}.
1047 */
1048 public boolean isLoggable(Level level);
1049
1050 /**
1051 * Logs a message.
1052 *
1053 * @implSpec The default implementation for this method calls
1054 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1055 *
1056 * @param level the log message level.
1057 * @param msg the string message (or a key in the message catalog, if
1058 * this logger is a {@link
1059 * LoggerFinder#getLocalizedLogger(java.lang.String,
1060 * java.util.ResourceBundle, java.lang.Module) localized logger});
1061 * can be {@code null}.
1062 *
1063 * @throws NullPointerException if {@code level} is {@code null}.
1064 */
1065 public default void log(Level level, String msg) {
1066 log(level, (ResourceBundle) null, msg, (Object[]) null);
1067 }
1068
1069 /**
1070 * Logs a lazily supplied message.
1071 *
1072 * If the logger is currently enabled for the given log message level
1073 * then a message is logged that is the result produced by the
1074 * given supplier function. Otherwise, the supplier is not operated on.
1075 *
1076 * @implSpec When logging is enabled for the given level, the default
1077 * implementation for this method calls
1078 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
1079 *
1080 * @param level the log message level.
1081 * @param msgSupplier a supplier function that produces a message.
1082 *
1083 * @throws NullPointerException if {@code level} is {@code null},
1084 * or {@code msgSupplier} is {@code null}.
1085 */
1086 public default void log(Level level, Supplier<String> msgSupplier) {
1087 Objects.requireNonNull(msgSupplier);
1088 if (isLoggable(Objects.requireNonNull(level))) {
1089 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1090 }
1091 }
1092
1093 /**
1094 * Logs a message produced from the given object.
1095 *
1096 * If the logger is currently enabled for the given log message level then
1097 * a message is logged that, by default, is the result produced from
1098 * calling toString on the given object.
1099 * Otherwise, the object is not operated on.
1100 *
1101 * @implSpec When logging is enabled for the given level, the default
1102 * implementation for this method calls
1103 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1104 *
1105 * @param level the log message level.
1106 * @param obj the object to log.
1107 *
1108 * @throws NullPointerException if {@code level} is {@code null}, or
1109 * {@code obj} is {@code null}.
1110 */
1111 public default void log(Level level, Object obj) {
1112 Objects.requireNonNull(obj);
1113 if (isLoggable(Objects.requireNonNull(level))) {
1114 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1115 }
1116 }
1117
1118 /**
1119 * Logs a message associated with a given throwable.
1120 *
1121 * @implSpec The default implementation for this method calls
1122 * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1123 *
1124 * @param level the log message level.
1125 * @param msg the string message (or a key in the message catalog, if
1126 * this logger is a {@link
1127 * LoggerFinder#getLocalizedLogger(java.lang.String,
1128 * java.util.ResourceBundle, java.lang.Module) localized logger});
1129 * can be {@code null}.
1130 * @param thrown a {@code Throwable} associated with the log message;
1131 * can be {@code null}.
1132 *
1133 * @throws NullPointerException if {@code level} is {@code null}.
1134 */
1135 public default void log(Level level, String msg, Throwable thrown) {
1136 this.log(level, null, msg, thrown);
1137 }
1138
1139 /**
1140 * Logs a lazily supplied message associated with a given throwable.
1141 *
1142 * If the logger is currently enabled for the given log message level
1143 * then a message is logged that is the result produced by the
1144 * given supplier function. Otherwise, the supplier is not operated on.
1145 *
1146 * @implSpec When logging is enabled for the given level, the default
1147 * implementation for this method calls
1148 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1149 *
1150 * @param level one of the log message level identifiers.
1151 * @param msgSupplier a supplier function that produces a message.
1152 * @param thrown a {@code Throwable} associated with log message;
1153 * can be {@code null}.
1154 *
1155 * @throws NullPointerException if {@code level} is {@code null}, or
1156 * {@code msgSupplier} is {@code null}.
1157 */
1158 public default void log(Level level, Supplier<String> msgSupplier,
1159 Throwable thrown) {
1160 Objects.requireNonNull(msgSupplier);
1161 if (isLoggable(Objects.requireNonNull(level))) {
1162 this.log(level, null, msgSupplier.get(), thrown);
1163 }
1164 }
1165
1166 /**
1167 * Logs a message with an optional list of parameters.
1168 *
1169 * @implSpec The default implementation for this method calls
1170 * {@code this.log(level, (ResourceBundle)null, format, params);}
1171 *
1172 * @param level one of the log message level identifiers.
1173 * @param format the string message format in {@link
1174 * java.text.MessageFormat} format, (or a key in the message
1175 * catalog, if this logger is a {@link
1176 * LoggerFinder#getLocalizedLogger(java.lang.String,
1177 * java.util.ResourceBundle, java.lang.Module) localized logger});
1178 * can be {@code null}.
1179 * @param params an optional list of parameters to the message (may be
1180 * none).
1181 *
1182 * @throws NullPointerException if {@code level} is {@code null}.
1183 */
1184 public default void log(Level level, String format, Object... params) {
1185 this.log(level, null, format, params);
1186 }
1187
1188 /**
1189 * Logs a localized message associated with a given throwable.
1190 *
1191 * If the given resource bundle is non-{@code null}, the {@code msg}
1192 * string is localized using the given resource bundle.
1193 * Otherwise the {@code msg} string is not localized.
1194 *
1195 * @param level the log message level.
1196 * @param bundle a resource bundle to localize {@code msg}; can be
1197 * {@code null}.
1198 * @param msg the string message (or a key in the message catalog,
1199 * if {@code bundle} is not {@code null}); can be {@code null}.
1200 * @param thrown a {@code Throwable} associated with the log message;
1201 * can be {@code null}.
1202 *
1203 * @throws NullPointerException if {@code level} is {@code null}.
1204 */
1205 public void log(Level level, ResourceBundle bundle, String msg,
1206 Throwable thrown);
1207
1208 /**
1209 * Logs a message with resource bundle and an optional list of
1210 * parameters.
1211 *
1212 * If the given resource bundle is non-{@code null}, the {@code format}
1213 * string is localized using the given resource bundle.
1214 * Otherwise the {@code format} string is not localized.
1215 *
1216 * @param level the log message level.
1217 * @param bundle a resource bundle to localize {@code format}; can be
1218 * {@code null}.
1219 * @param format the string message format in {@link
1220 * java.text.MessageFormat} format, (or a key in the message
1221 * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1222 * @param params an optional list of parameters to the message (may be
1223 * none).
1224 *
1225 * @throws NullPointerException if {@code level} is {@code null}.
1226 */
1227 public void log(Level level, ResourceBundle bundle, String format,
1228 Object... params);
1229 }
1230
1231 /**
1232 * The {@code LoggerFinder} service is responsible for creating, managing,
1233 * and configuring loggers to the underlying framework it uses.
1234 *
1235 * A logger finder is a concrete implementation of this class that has a
1236 * zero-argument constructor and implements the abstract methods defined
1237 * by this class.
1238 * The loggers returned from a logger finder are capable of routing log
1239 * messages to the logging backend this provider supports.
1240 * A given invocation of the Java Runtime maintains a single
1241 * system-wide LoggerFinder instance that is loaded as follows:
1242 * <ul>
1243 * <li>First it finds any custom {@code LoggerFinder} provider
1244 * using the {@link java.util.ServiceLoader} facility with the
1245 * {@linkplain ClassLoader#getSystemClassLoader() system class
1246 * loader}.</li>
1247 * <li>If no {@code LoggerFinder} provider is found, the system default
1248 * {@code LoggerFinder} implementation will be used.</li>
1249 * </ul>
1250 * <p>
1251 * An application can replace the logging backend
1252 * <i>even when the java.logging module is present</i>, by simply providing
1253 * and declaring an implementation of the {@link LoggerFinder} service.
1254 * <p>
1255 * <b>Default Implementation</b>
1256 * <p>
1257 * The system default {@code LoggerFinder} implementation uses
1258 * {@code java.util.logging} as the backend framework when the
1259 * {@code java.logging} module is present.
1260 * It returns a {@linkplain System.Logger logger} instance
1261 * that will route log messages to a {@link java.logging/java.util.logging.Logger
1262 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1263 * present, the default implementation will return a simple logger
1264 * instance that will route log messages of {@code INFO} level and above to
1265 * the console ({@code System.err}).
1266 * <p>
1267 * <b>Logging Configuration</b>
1268 * <p>
1269 * {@linkplain Logger Logger} instances obtained from the
1270 * {@code LoggerFinder} factory methods are not directly configurable by
1271 * the application. Configuration is the responsibility of the underlying
1272 * logging backend, and usually requires using APIs specific to that backend.
1273 * <p>For the default {@code LoggerFinder} implementation
1274 * using {@code java.util.logging} as its backend, refer to
1275 * {@link java.logging/java.util.logging java.util.logging} for logging configuration.
1276 * For the default {@code LoggerFinder} implementation returning simple loggers
1277 * when the {@code java.logging} module is absent, the configuration
1278 * is implementation dependent.
1279 * <p>
1280 * Usually an application that uses a logging framework will log messages
1281 * through a logger facade defined (or supported) by that framework.
1282 * Applications that wish to use an external framework should log
1283 * through the facade associated with that framework.
1284 * <p>
1285 * A system class that needs to log messages will typically obtain
1286 * a {@link System.Logger} instance to route messages to the logging
1287 * framework selected by the application.
1288 * <p>
1289 * Libraries and classes that only need loggers to produce log messages
1290 * should not attempt to configure loggers by themselves, as that
1291 * would make them dependent from a specific implementation of the
1292 * {@code LoggerFinder} service.
1293 * <p>
1294 * <b>Message Levels and Mapping to backend levels</b>
1295 * <p>
1296 * A logger finder is responsible for mapping from a {@code
1297 * System.Logger.Level} to a level supported by the logging backend it uses.
1298 * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1299 * maps {@code System.Logger} levels to
1300 * {@linkplain java.logging/java.util.logging.Level java.util.logging} levels
1301 * of corresponding severity - as described in {@link Logger.Level
1302 * Logger.Level}.
1303 *
1304 * @see java.lang.System
1305 * @see java.lang.System.Logger
1306 *
1307 * @since 9
1308 */
1309 @SuppressWarnings("doclint:reference") // cross-module links
1310 public abstract static class LoggerFinder {
1311
1312 /**
1313 * Creates a new instance of {@code LoggerFinder}.
1314 *
1315 * @implNote It is recommended that a {@code LoggerFinder} service
1316 * implementation does not perform any heavy initialization in its
1317 * constructor, in order to avoid possible risks of deadlock or class
1318 * loading cycles during the instantiation of the service provider.
1319 */
1320 protected LoggerFinder() {
1321 }
1322
1323 /**
1324 * Returns an instance of {@link Logger Logger}
1325 * for the given {@code module}.
1326 *
1327 * @param name the name of the logger.
1328 * @param module the module for which the logger is being requested.
1329 *
1330 * @return a {@link Logger logger} suitable for use within the given
1331 * module.
1332 * @throws NullPointerException if {@code name} is {@code null} or
1333 * {@code module} is {@code null}.
1334 */
1335 public abstract Logger getLogger(String name, Module module);
1336
1337 /**
1338 * Returns a localizable instance of {@link Logger Logger}
1339 * for the given {@code module}.
1340 * The returned logger will use the provided resource bundle for
1341 * message localization.
1342 *
1343 * @implSpec By default, this method calls {@link
1344 * #getLogger(java.lang.String, java.lang.Module)
1345 * this.getLogger(name, module)} to obtain a logger, then wraps that
1346 * logger in a {@link Logger} instance where all methods that do not
1347 * take a {@link ResourceBundle} as parameter are redirected to one
1348 * which does - passing the given {@code bundle} for
1349 * localization. So for instance, a call to {@link
1350 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1351 * will end up as a call to {@link
1352 * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1353 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1354 * logger instance.
1355 * Note however that by default, string messages returned by {@link
1356 * java.util.function.Supplier Supplier<String>} will not be
1357 * localized, as it is assumed that such strings are messages which are
1358 * already constructed, rather than keys in a resource bundle.
1359 * <p>
1360 * An implementation of {@code LoggerFinder} may override this method,
1361 * for example, when the underlying logging backend provides its own
1362 * mechanism for localizing log messages, then such a
1363 * {@code LoggerFinder} would be free to return a logger
1364 * that makes direct use of the mechanism provided by the backend.
1365 *
1366 * @param name the name of the logger.
1367 * @param bundle a resource bundle; can be {@code null}.
1368 * @param module the module for which the logger is being requested.
1369 * @return an instance of {@link Logger Logger} which will use the
1370 * provided resource bundle for message localization.
1371 *
1372 * @throws NullPointerException if {@code name} is {@code null} or
1373 * {@code module} is {@code null}.
1374 */
1375 public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1376 Module module) {
1377 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1378 }
1379
1380 /**
1381 * Returns the {@code LoggerFinder} instance. There is one
1382 * single system-wide {@code LoggerFinder} instance in
1383 * the Java Runtime. See the class specification of how the
1384 * {@link LoggerFinder LoggerFinder} implementation is located and
1385 * loaded.
1386 *
1387 * @return the {@link LoggerFinder LoggerFinder} instance.
1388 */
1389 public static LoggerFinder getLoggerFinder() {
1390 return accessProvider();
1391 }
1392
1393
1394 private static volatile LoggerFinder service;
1395 static LoggerFinder accessProvider() {
1396 // We do not need to synchronize: LoggerFinderLoader will
1397 // always return the same instance, so if we don't have it,
1398 // just fetch it again.
1399 LoggerFinder finder = service;
1400 if (finder == null) {
1401 finder = LoggerFinderLoader.getLoggerFinder();
1402 if (finder instanceof TemporaryLoggerFinder) return finder;
1403 service = finder;
1404 }
1405 return finder;
1406 }
1407
1408 }
1409
1410
1411 /**
1412 * Returns an instance of {@link Logger Logger} for the caller's
1413 * use.
1414 *
1415 * @implSpec
1416 * Instances returned by this method route messages to loggers
1417 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1418 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1419 * {@code module} is the caller's module.
1420 * In cases where {@code System.getLogger} is called from a context where
1421 * there is no caller frame on the stack (e.g when called directly
1422 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1423 * To obtain a logger in such a context, use an auxiliary class that will
1424 * implicitly be identified as the caller, or use the system {@link
1425 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1426 * Note that doing the latter may eagerly initialize the underlying
1427 * logging system.
1428 *
1429 * @apiNote
1430 * This method may defer calling the {@link
1431 * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1432 * LoggerFinder.getLogger} method to create an actual logger supplied by
1433 * the logging backend, for instance, to allow loggers to be obtained during
1434 * the system initialization time.
1435 *
1436 * @param name the name of the logger.
1437 * @return an instance of {@link Logger} that can be used by the calling
1438 * class.
1439 * @throws NullPointerException if {@code name} is {@code null}.
1440 * @throws IllegalCallerException if there is no Java caller frame on the
1441 * stack.
1442 *
1443 * @since 9
1444 */
1445 @CallerSensitive
1446 public static Logger getLogger(String name) {
1447 Objects.requireNonNull(name);
1448 final Class<?> caller = Reflection.getCallerClass();
1449 if (caller == null) {
1450 throw new IllegalCallerException("no caller frame");
1451 }
1452 return LazyLoggers.getLogger(name, caller.getModule());
1453 }
1454
1455 /**
1456 * Returns a localizable instance of {@link Logger
1457 * Logger} for the caller's use.
1458 * The returned logger will use the provided resource bundle for message
1459 * localization.
1460 *
1461 * @implSpec
1462 * The returned logger will perform message localization as specified
1463 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1464 * java.util.ResourceBundle, java.lang.Module)
1465 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1466 * {@code module} is the caller's module.
1467 * In cases where {@code System.getLogger} is called from a context where
1468 * there is no caller frame on the stack (e.g when called directly
1469 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1470 * To obtain a logger in such a context, use an auxiliary class that
1471 * will implicitly be identified as the caller, or use the system {@link
1472 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1473 * Note that doing the latter may eagerly initialize the underlying
1474 * logging system.
1475 *
1476 * @apiNote
1477 * This method is intended to be used after the system is fully initialized.
1478 * This method may trigger the immediate loading and initialization
1479 * of the {@link LoggerFinder} service, which may cause issues if the
1480 * Java Runtime is not ready to initialize the concrete service
1481 * implementation yet.
1482 * System classes which may be loaded early in the boot sequence and
1483 * need to log localized messages should create a logger using
1484 * {@link #getLogger(java.lang.String)} and then use the log methods that
1485 * take a resource bundle as parameter.
1486 *
1487 * @param name the name of the logger.
1488 * @param bundle a resource bundle.
1489 * @return an instance of {@link Logger} which will use the provided
1490 * resource bundle for message localization.
1491 * @throws NullPointerException if {@code name} is {@code null} or
1492 * {@code bundle} is {@code null}.
1493 * @throws IllegalCallerException if there is no Java caller frame on the
1494 * stack.
1495 *
1496 * @since 9
1497 */
1498 @CallerSensitive
1499 public static Logger getLogger(String name, ResourceBundle bundle) {
1500 final ResourceBundle rb = Objects.requireNonNull(bundle);
1501 Objects.requireNonNull(name);
1502 final Class<?> caller = Reflection.getCallerClass();
1503 if (caller == null) {
1504 throw new IllegalCallerException("no caller frame");
1505 }
1506 return LoggerFinder.accessProvider()
1507 .getLocalizedLogger(name, rb, caller.getModule());
1508 }
1509
1510 /**
1511 * Initiates the {@linkplain Runtime##shutdown shutdown sequence} of the Java Virtual
1512 * Machine. This method initiates the shutdown sequence (if it is not already initiated)
1513 * and then blocks indefinitely. This method neither returns nor throws an exception;
1514 * that is, it does not complete either normally or abruptly.
1515 * <p>
1516 * The argument serves as a status code. By convention, a nonzero status code
1517 * indicates abnormal termination.
1518 * <p>
1519 * The call {@code System.exit(n)} is effectively equivalent to the call:
1520 * {@snippet :
1521 * Runtime.getRuntime().exit(n)
1522 * }
1523 *
1524 * @implNote
1525 * The initiation of the shutdown sequence is logged by {@link Runtime#exit(int)}.
1526 *
1527 * @param status exit status.
1528 * @see java.lang.Runtime#exit(int)
1529 */
1530 public static void exit(int status) {
1531 Runtime.getRuntime().exit(status);
1532 }
1533
1534 /**
1535 * Runs the garbage collector in the Java Virtual Machine.
1536 * <p>
1537 * Calling the {@code gc} method suggests that the Java Virtual Machine
1538 * expend effort toward recycling unused objects in order to
1539 * make the memory they currently occupy available for reuse
1540 * by the Java Virtual Machine.
1541 * When control returns from the method call, the Java Virtual Machine
1542 * has made a best effort to reclaim space from all unused objects.
1543 * There is no guarantee that this effort will recycle any particular
1544 * number of unused objects, reclaim any particular amount of space, or
1545 * complete at any particular time, if at all, before the method returns or ever.
1546 * There is also no guarantee that this effort will determine
1547 * the change of reachability in any particular number of objects,
1548 * or that any particular number of {@link java.lang.ref.Reference Reference}
1549 * objects will be cleared and enqueued.
1550 *
1551 * <p>
1552 * The call {@code System.gc()} is effectively equivalent to the
1553 * call:
1554 * <blockquote><pre>
1555 * Runtime.getRuntime().gc()
1556 * </pre></blockquote>
1557 *
1558 * @see java.lang.Runtime#gc()
1559 */
1560 public static void gc() {
1561 Runtime.getRuntime().gc();
1562 }
1563
1564 /**
1565 * Runs the finalization methods of any objects pending finalization.
1566 *
1567 * Calling this method suggests that the Java Virtual Machine expend
1568 * effort toward running the {@code finalize} methods of objects
1569 * that have been found to be discarded but whose {@code finalize}
1570 * methods have not yet been run. When control returns from the
1571 * method call, the Java Virtual Machine has made a best effort to
1572 * complete all outstanding finalizations.
1573 * <p>
1574 * The call {@code System.runFinalization()} is effectively
1575 * equivalent to the call:
1576 * <blockquote><pre>
1577 * Runtime.getRuntime().runFinalization()
1578 * </pre></blockquote>
1579 *
1580 * @deprecated Finalization has been deprecated for removal. See
1581 * {@link java.lang.Object#finalize} for background information and details
1582 * about migration options.
1583 * <p>
1584 * When running in a JVM in which finalization has been disabled or removed,
1585 * no objects will be pending finalization, so this method does nothing.
1586 *
1587 * @see java.lang.Runtime#runFinalization()
1588 * @jls 12.6 Finalization of Class Instances
1589 */
1590 @Deprecated(since="18", forRemoval=true)
1591 @SuppressWarnings("removal")
1592 public static void runFinalization() {
1593 Runtime.getRuntime().runFinalization();
1594 }
1595
1596 /**
1597 * Loads the native library specified by the filename argument. The filename
1598 * argument must be an absolute path name.
1599 *
1600 * If the filename argument, when stripped of any platform-specific library
1601 * prefix, path, and file extension, indicates a library whose name is,
1602 * for example, L, and a native library called L is statically linked
1603 * with the VM, then the JNI_OnLoad_L function exported by the library
1604 * is invoked rather than attempting to load a dynamic library.
1605 * A filename matching the argument does not have to exist in the
1606 * file system.
1607 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1608 * for more details.
1609 *
1610 * Otherwise, the filename argument is mapped to a native library image in
1611 * an implementation-dependent manner.
1612 *
1613 * <p>
1614 * The call {@code System.load(name)} is effectively equivalent
1615 * to the call:
1616 * <blockquote><pre>
1617 * Runtime.getRuntime().load(name)
1618 * </pre></blockquote>
1619 *
1620 * @param filename the file to load.
1621 * @throws UnsatisfiedLinkError if either the filename is not an
1622 * absolute path name, the native library is not statically
1623 * linked with the VM, or the library cannot be mapped to
1624 * a native library image by the host system.
1625 * @throws NullPointerException if {@code filename} is {@code null}
1626 * @throws IllegalCallerException if the caller is in a module that
1627 * does not have native access enabled.
1628 *
1629 * @spec jni/index.html Java Native Interface Specification
1630 * @see java.lang.Runtime#load(java.lang.String)
1631 */
1632 @CallerSensitive
1633 @Restricted
1634 public static void load(String filename) {
1635 Class<?> caller = Reflection.getCallerClass();
1636 Reflection.ensureNativeAccess(caller, System.class, "load", false);
1637 Runtime.getRuntime().load0(caller, filename);
1638 }
1639
1640 /**
1641 * Loads the native library specified by the {@code libname}
1642 * argument. The {@code libname} argument must not contain any platform
1643 * specific prefix, file extension or path. If a native library
1644 * called {@code libname} is statically linked with the VM, then the
1645 * JNI_OnLoad_{@code libname} function exported by the library is invoked.
1646 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1647 * for more details.
1648 *
1649 * Otherwise, the libname argument is loaded from a system library
1650 * location and mapped to a native library image in an
1651 * implementation-dependent manner.
1652 * <p>
1653 * The call {@code System.loadLibrary(name)} is effectively
1654 * equivalent to the call
1655 * <blockquote><pre>
1656 * Runtime.getRuntime().loadLibrary(name)
1657 * </pre></blockquote>
1658 *
1659 * @param libname the name of the library.
1660 * @throws UnsatisfiedLinkError if either the libname argument
1661 * contains a file path, the native library is not statically
1662 * linked with the VM, or the library cannot be mapped to a
1663 * native library image by the host system.
1664 * @throws NullPointerException if {@code libname} is {@code null}
1665 * @throws IllegalCallerException if the caller is in a module that
1666 * does not have native access enabled.
1667 *
1668 * @spec jni/index.html Java Native Interface Specification
1669 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1670 */
1671 @CallerSensitive
1672 @Restricted
1673 public static void loadLibrary(String libname) {
1674 Class<?> caller = Reflection.getCallerClass();
1675 Reflection.ensureNativeAccess(caller, System.class, "loadLibrary", false);
1676 Runtime.getRuntime().loadLibrary0(caller, libname);
1677 }
1678
1679 /**
1680 * Maps a library name into a platform-specific string representing
1681 * a native library.
1682 *
1683 * @param libname the name of the library.
1684 * @return a platform-dependent native library name.
1685 * @throws NullPointerException if {@code libname} is {@code null}
1686 * @see java.lang.System#loadLibrary(java.lang.String)
1687 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1688 * @since 1.2
1689 */
1690 public static native String mapLibraryName(String libname);
1691
1692 /**
1693 * Create PrintStream for stdout/err based on encoding.
1694 */
1695 private static PrintStream newPrintStream(OutputStream out, String enc) {
1696 if (enc != null) {
1697 return new PrintStream(new BufferedOutputStream(out, 128), true,
1698 Charset.forName(enc, UTF_8.INSTANCE));
1699 }
1700 return new PrintStream(new BufferedOutputStream(out, 128), true);
1701 }
1702
1703 /**
1704 * Logs an exception/error at initialization time to stdout or stderr.
1705 *
1706 * @param printToStderr to print to stderr rather than stdout
1707 * @param printStackTrace to print the stack trace
1708 * @param msg the message to print before the exception, can be {@code null}
1709 * @param e the exception or error
1710 */
1711 private static void logInitException(boolean printToStderr,
1712 boolean printStackTrace,
1713 String msg,
1714 Throwable e) {
1715 if (VM.initLevel() < 1) {
1716 throw new InternalError("system classes not initialized");
1717 }
1718 PrintStream log = (printToStderr) ? err : out;
1719 if (msg != null) {
1720 log.println(msg);
1721 }
1722 if (printStackTrace) {
1723 e.printStackTrace(log);
1724 } else {
1725 log.println(e);
1726 for (Throwable suppressed : e.getSuppressed()) {
1727 log.println("Suppressed: " + suppressed);
1728 }
1729 Throwable cause = e.getCause();
1730 if (cause != null) {
1731 log.println("Caused by: " + cause);
1732 }
1733 }
1734 }
1735
1736 /**
1737 * Create the Properties object from a map - masking out system properties
1738 * that are not intended for public access.
1739 */
1740 private static Properties createProperties(Map<String, String> initialProps) {
1741 Properties properties = new Properties(initialProps.size());
1742 for (var entry : initialProps.entrySet()) {
1743 String prop = entry.getKey();
1744 switch (prop) {
1745 // Do not add private system properties to the Properties
1746 case "sun.nio.MaxDirectMemorySize":
1747 case "sun.nio.PageAlignDirectMemory":
1748 // used by java.lang.Integer.IntegerCache
1749 case "java.lang.Integer.IntegerCache.high":
1750 // used by sun.launcher.LauncherHelper
1751 case "sun.java.launcher.diag":
1752 // used by jdk.internal.loader.ClassLoaders
1753 case "jdk.boot.class.path.append":
1754 break;
1755 default:
1756 properties.put(prop, entry.getValue());
1757 }
1758 }
1759 return properties;
1760 }
1761
1762 /**
1763 * Initialize the system class. Called after thread initialization.
1764 */
1765 private static void initPhase1() {
1766
1767 // register the shared secrets - do this first, since SystemProps.initProperties
1768 // might initialize CharsetDecoders that rely on it
1769 setJavaLangAccess();
1770
1771 // VM might invoke JNU_NewStringPlatform() to set those encoding
1772 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1773 // during "props" initialization.
1774 // The charset is initialized in System.c and does not depend on the Properties.
1775 Map<String, String> tempProps = SystemProps.initProperties();
1776 VersionProps.init(tempProps);
1777
1778 // There are certain system configurations that may be controlled by
1779 // VM options such as the maximum amount of direct memory and
1780 // Integer cache size used to support the object identity semantics
1781 // of autoboxing. Typically, the library will obtain these values
1782 // from the properties set by the VM. If the properties are for
1783 // internal implementation use only, these properties should be
1784 // masked from the system properties.
1785 //
1786 // Save a private copy of the system properties object that
1787 // can only be accessed by the internal implementation.
1788 VM.saveProperties(tempProps);
1789 props = createProperties(tempProps);
1790
1791 // Check if sun.jnu.encoding is supported. If not, replace it with UTF-8.
1792 var jnuEncoding = props.getProperty("sun.jnu.encoding");
1793 if (jnuEncoding == null || !Charset.isSupported(jnuEncoding)) {
1794 notSupportedJnuEncoding = jnuEncoding == null ? "null" : jnuEncoding;
1795 props.setProperty("sun.jnu.encoding", "UTF-8");
1796 }
1797
1798 StaticProperty.javaHome(); // Load StaticProperty to cache the property values
1799
1800 lineSeparator = props.getProperty("line.separator");
1801
1802 FileInputStream fdIn = new In(FileDescriptor.in);
1803 FileOutputStream fdOut = new Out(FileDescriptor.out);
1804 FileOutputStream fdErr = new Out(FileDescriptor.err);
1805 initialIn = new BufferedInputStream(fdIn);
1806 setIn0(initialIn);
1807 // stdout/err.encoding are set when the VM is associated with the terminal,
1808 // thus they are equivalent to Console.charset(), otherwise the encodings
1809 // of those properties default to native.encoding
1810 setOut0(newPrintStream(fdOut, props.getProperty("stdout.encoding")));
1811 initialErr = newPrintStream(fdErr, props.getProperty("stderr.encoding"));
1812 setErr0(initialErr);
1813
1814 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1815 Terminator.setup();
1816
1817 // Initialize any miscellaneous operating system settings that need to be
1818 // set for the class libraries. Currently this is no-op everywhere except
1819 // for Windows where the process-wide error mode is set before the java.io
1820 // classes are used.
1821 VM.initializeOSEnvironment();
1822
1823 // start Finalizer and Reference Handler threads
1824 SharedSecrets.getJavaLangRefAccess().startThreads();
1825
1826 // system properties, java.lang and other core classes are now initialized
1827 VM.initLevel(1);
1828 }
1829
1830 /**
1831 * System.in.
1832 */
1833 private static class In extends FileInputStream {
1834 In(FileDescriptor fd) {
1835 super(fd);
1836 }
1837
1838 @Override
1839 public int read() throws IOException {
1840 boolean attempted = Blocker.begin();
1841 try {
1842 return super.read();
1843 } finally {
1844 Blocker.end(attempted);
1845 }
1846 }
1847
1848 @Override
1849 public int read(byte[] b) throws IOException {
1850 boolean attempted = Blocker.begin();
1851 try {
1852 return super.read(b);
1853 } finally {
1854 Blocker.end(attempted);
1855 }
1856 }
1857
1858 @Override
1859 public int read(byte[] b, int off, int len) throws IOException {
1860 boolean attempted = Blocker.begin();
1861 try {
1862 return super.read(b, off, len);
1863 } finally {
1864 Blocker.end(attempted);
1865 }
1866 }
1867 }
1868
1869 /**
1870 * System.out/System.err wrap this output stream.
1871 */
1872 private static class Out extends FileOutputStream {
1873 Out(FileDescriptor fd) {
1874 super(fd);
1875 }
1876
1877 @Override
1878 public void write(int b) throws IOException {
1879 boolean attempted = Blocker.begin();
1880 try {
1881 super.write(b);
1882 } finally {
1883 Blocker.end(attempted);
1884 }
1885 }
1886
1887 @Override
1888 public void write(byte[] b) throws IOException {
1889 boolean attempted = Blocker.begin();
1890 try {
1891 super.write(b);
1892 } finally {
1893 Blocker.end(attempted);
1894 }
1895 }
1896
1897 @Override
1898 public void write(byte[] b, int off, int len) throws IOException {
1899 boolean attempted = Blocker.begin();
1900 try {
1901 super.write(b, off, len);
1902 } finally {
1903 Blocker.end(attempted);
1904 }
1905 }
1906 }
1907
1908 // @see #initPhase2()
1909 static ModuleLayer bootLayer;
1910
1911 /*
1912 * Invoked by VM. Phase 2 module system initialization.
1913 * Only classes in java.base can be loaded in this phase.
1914 *
1915 * @param printToStderr print exceptions to stderr rather than stdout
1916 * @param printStackTrace print stack trace when exception occurs
1917 *
1918 * @return JNI_OK for success, JNI_ERR for failure
1919 */
1920 private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
1921
1922 try {
1923 bootLayer = ModuleBootstrap.boot();
1924 } catch (Exception | Error e) {
1925 logInitException(printToStderr, printStackTrace,
1926 "Error occurred during initialization of boot layer", e);
1927 return -1; // JNI_ERR
1928 }
1929
1930 // module system initialized
1931 VM.initLevel(2);
1932
1933 return 0; // JNI_OK
1934 }
1935
1936 /*
1937 * Invoked by VM. Phase 3 is the final system initialization:
1938 * 1. set system class loader
1939 * 2. set TCCL
1940 *
1941 * This method must be called after the module system initialization.
1942 */
1943 private static void initPhase3() {
1944
1945 // Emit a warning if java.io.tmpdir is set via the command line
1946 // to a directory that doesn't exist
1947 if (SystemProps.isBadIoTmpdir()) {
1948 System.err.println("WARNING: java.io.tmpdir directory does not exist");
1949 }
1950
1951 String smProp = System.getProperty("java.security.manager");
1952 if (smProp != null) {
1953 switch (smProp) {
1954 case "disallow":
1955 break;
1956 case "allow":
1957 case "":
1958 case "default":
1959 default:
1960 throw new Error("A command line option has attempted to allow or enable the Security Manager."
1961 + " Enabling a Security Manager is not supported.");
1962 }
1963 }
1964
1965 // Emit a warning if `sun.jnu.encoding` is not supported.
1966 if (notSupportedJnuEncoding != null) {
1967 System.err.println(
1968 "WARNING: The encoding of the underlying platform's" +
1969 " file system is not supported: " +
1970 notSupportedJnuEncoding);
1971 }
1972
1973 // initializing the system class loader
1974 VM.initLevel(3);
1975
1976 // system class loader initialized
1977 ClassLoader scl = ClassLoader.initSystemClassLoader();
1978
1979 // set TCCL
1980 Thread.currentThread().setContextClassLoader(scl);
1981
1982 // system is fully initialized
1983 VM.initLevel(4);
1984 }
1985
1986 private static void setJavaLangAccess() {
1987 // Allow privileged classes outside of java.lang
1988 SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
1989 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
1990 return klass.getDeclaredPublicMethods(name, parameterTypes);
1991 }
1992 public Method findMethod(Class<?> klass, boolean publicOnly, String name, Class<?>... parameterTypes) {
1993 return klass.findMethod(publicOnly, name, parameterTypes);
1994 }
1995 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
1996 return klass.getConstantPool();
1997 }
1998 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
1999 return klass.casAnnotationType(oldType, newType);
2000 }
2001 public AnnotationType getAnnotationType(Class<?> klass) {
2002 return klass.getAnnotationType();
2003 }
2004 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2005 return klass.getDeclaredAnnotationMap();
2006 }
2007 public byte[] getRawClassAnnotations(Class<?> klass) {
2008 return klass.getRawAnnotations();
2009 }
2010 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2011 return klass.getRawTypeAnnotations();
2012 }
2013 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2014 return Class.getExecutableTypeAnnotationBytes(executable);
2015 }
2016 public <E extends Enum<E>>
2017 E[] getEnumConstantsShared(Class<E> klass) {
2018 return klass.getEnumConstantsShared();
2019 }
2020 public void blockedOn(Interruptible b) {
2021 Thread.currentThread().blockedOn(b);
2022 }
2023 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2024 Shutdown.add(slot, registerShutdownInProgress, hook);
2025 }
2026 @SuppressWarnings("removal")
2027 public void invokeFinalize(Object o) throws Throwable {
2028 o.finalize();
2029 }
2030 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2031 return cl.createOrGetClassLoaderValueMap();
2032 }
2033 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2034 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2035 }
2036 public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd,
2037 boolean initialize, int flags, Object classData) {
2038 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData);
2039 }
2040 public Class<?> findBootstrapClassOrNull(String name) {
2041 return ClassLoader.findBootstrapClassOrNull(name);
2042 }
2043 public Package definePackage(ClassLoader cl, String name, Module module) {
2044 return cl.definePackage(name, module);
2045 }
2046 public Module defineModule(ClassLoader loader,
2047 ModuleDescriptor descriptor,
2048 URI uri) {
2049 return new Module(null, loader, descriptor, uri);
2050 }
2051 public Module defineUnnamedModule(ClassLoader loader) {
2052 return new Module(loader);
2053 }
2054 public void addReads(Module m1, Module m2) {
2055 m1.implAddReads(m2);
2056 }
2057 public void addReadsAllUnnamed(Module m) {
2058 m.implAddReadsAllUnnamed();
2059 }
2060 public void addExports(Module m, String pn) {
2061 m.implAddExports(pn);
2062 }
2063 public void addExports(Module m, String pn, Module other) {
2064 m.implAddExports(pn, other);
2065 }
2066 public void addExportsToAllUnnamed(Module m, String pn) {
2067 m.implAddExportsToAllUnnamed(pn);
2068 }
2069 public void addOpens(Module m, String pn, Module other) {
2070 m.implAddOpens(pn, other);
2071 }
2072 public void addOpensToAllUnnamed(Module m, String pn) {
2073 m.implAddOpensToAllUnnamed(pn);
2074 }
2075 public void addUses(Module m, Class<?> service) {
2076 m.implAddUses(service);
2077 }
2078 public boolean isReflectivelyExported(Module m, String pn, Module other) {
2079 return m.isReflectivelyExported(pn, other);
2080 }
2081 public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2082 return m.isReflectivelyOpened(pn, other);
2083 }
2084 public Module addEnableNativeAccess(Module m) {
2085 return m.implAddEnableNativeAccess();
2086 }
2087 public boolean addEnableNativeAccess(ModuleLayer layer, String name) {
2088 return layer.addEnableNativeAccess(name);
2089 }
2090 public void addEnableNativeAccessToAllUnnamed() {
2091 Module.implAddEnableNativeAccessToAllUnnamed();
2092 }
2093 public void ensureNativeAccess(Module m, Class<?> owner, String methodName, Class<?> currentClass, boolean jni) {
2094 m.ensureNativeAccess(owner, methodName, currentClass, jni);
2095 }
2096 public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2097 return layer.getServicesCatalog();
2098 }
2099 public void bindToLoader(ModuleLayer layer, ClassLoader loader) {
2100 layer.bindToLoader(loader);
2101 }
2102 public Stream<ModuleLayer> layers(ModuleLayer layer) {
2103 return layer.layers();
2104 }
2105 public Stream<ModuleLayer> layers(ClassLoader loader) {
2106 return ModuleLayer.layers(loader);
2107 }
2108
2109 public int countPositives(byte[] bytes, int offset, int length) {
2110 return StringCoding.countPositives(bytes, offset, length);
2111 }
2112 public int countNonZeroAscii(String s) {
2113 return StringCoding.countNonZeroAscii(s);
2114 }
2115 public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
2116 return String.newStringNoRepl(bytes, cs);
2117 }
2118 public char getUTF16Char(byte[] bytes, int index) {
2119 return StringUTF16.getChar(bytes, index);
2120 }
2121 public void putCharUTF16(byte[] bytes, int index, int ch) {
2122 StringUTF16.putChar(bytes, index, ch);
2123 }
2124 public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2125 return String.getBytesNoRepl(s, cs);
2126 }
2127
2128 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2129 return String.newStringUTF8NoRepl(bytes, off, len, true);
2130 }
2131
2132 public byte[] getBytesUTF8NoRepl(String s) {
2133 return String.getBytesUTF8NoRepl(s);
2134 }
2135
2136 public void inflateBytesToChars(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2137 StringLatin1.inflate(src, srcOff, dst, dstOff, len);
2138 }
2139
2140 public int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2141 return String.decodeASCII(src, srcOff, dst, dstOff, len);
2142 }
2143
2144 public int encodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len) {
2145 return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
2146 }
2147
2148 public InputStream initialSystemIn() {
2149 return initialIn;
2150 }
2151
2152 public PrintStream initialSystemErr() {
2153 return initialErr;
2154 }
2155
2156 public void setCause(Throwable t, Throwable cause) {
2157 t.setCause(cause);
2158 }
2159
2160 public ProtectionDomain protectionDomain(Class<?> c) {
2161 return c.getProtectionDomain();
2162 }
2163
2164 public MethodHandle stringConcatHelper(String name, MethodType methodType) {
2165 return StringConcatHelper.lookupStatic(name, methodType);
2166 }
2167
2168 public long stringConcatInitialCoder() {
2169 return StringConcatHelper.initialCoder();
2170 }
2171
2172 public long stringConcatMix(long lengthCoder, String constant) {
2173 return StringConcatHelper.mix(lengthCoder, constant);
2174 }
2175
2176 public long stringConcatMix(long lengthCoder, char value) {
2177 return StringConcatHelper.mix(lengthCoder, value);
2178 }
2179
2180 public Object stringConcat1(String[] constants) {
2181 return new StringConcatHelper.Concat1(constants);
2182 }
2183
2184 public byte stringInitCoder() {
2185 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
2186 }
2187
2188 public byte stringCoder(String str) {
2189 return str.coder();
2190 }
2191
2192 public String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
2193 return String.join(prefix, suffix, delimiter, elements, size);
2194 }
2195
2196 public String concat(String prefix, Object value, String suffix) {
2197 return StringConcatHelper.concat(prefix, value, suffix);
2198 }
2199
2200 public Object classData(Class<?> c) {
2201 return c.getClassData();
2202 }
2203
2204 @Override
2205 public NativeLibraries nativeLibrariesFor(ClassLoader loader) {
2206 return ClassLoader.nativeLibrariesFor(loader);
2207 }
2208
2209 public Thread[] getAllThreads() {
2210 return Thread.getAllThreads();
2211 }
2212
2213 public ThreadContainer threadContainer(Thread thread) {
2214 return thread.threadContainer();
2215 }
2216
2217 public void start(Thread thread, ThreadContainer container) {
2218 thread.start(container);
2219 }
2220
2221 public StackableScope headStackableScope(Thread thread) {
2222 return thread.headStackableScopes();
2223 }
2224
2225 public void setHeadStackableScope(StackableScope scope) {
2226 Thread.setHeadStackableScope(scope);
2227 }
2228
2229 public Thread currentCarrierThread() {
2230 return Thread.currentCarrierThread();
2231 }
2232
2233 public Thread getCarrierThread(Thread thread) {
2234 if (thread instanceof VirtualThread vthread) {
2235 return vthread.carrierThread();
2236 } else {
2237 throw new UnsupportedOperationException();
2238 }
2239 }
2240
2241 public int getInternalState(Thread thread) {
2242 if (thread instanceof VirtualThread vthread) {
2243 return vthread.state();
2244 } else {
2245 throw new UnsupportedOperationException();
2246 }
2247 }
2248
2249 public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
2250 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
2251 }
2252
2253 public <T> void setCarrierThreadLocal(CarrierThreadLocal<T> local, T value) {
2254 ((ThreadLocal<T>)local).setCarrierThreadLocal(value);
2255 }
2256
2257 public void removeCarrierThreadLocal(CarrierThreadLocal<?> local) {
2258 ((ThreadLocal<?>)local).removeCarrierThreadLocal();
2259 }
2260
2261 public boolean isCarrierThreadLocalPresent(CarrierThreadLocal<?> local) {
2262 return ((ThreadLocal<?>)local).isCarrierThreadLocalPresent();
2263 }
2264
2265 public Object[] scopedValueCache() {
2266 return Thread.scopedValueCache();
2267 }
2268
2269 public void setScopedValueCache(Object[] cache) {
2270 Thread.setScopedValueCache(cache);
2271 }
2272
2273 public Object scopedValueBindings() {
2274 return Thread.scopedValueBindings();
2275 }
2276
2277 public Continuation getContinuation(Thread thread) {
2278 return thread.getContinuation();
2279 }
2280
2281 public void setContinuation(Thread thread, Continuation continuation) {
2282 thread.setContinuation(continuation);
2283 }
2284
2285 public ContinuationScope virtualThreadContinuationScope() {
2286 return VirtualThread.continuationScope();
2287 }
2288
2289 public void parkVirtualThread() {
2290 Thread thread = Thread.currentThread();
2291 if (thread instanceof BaseVirtualThread vthread) {
2292 vthread.park();
2293 } else {
2294 throw new WrongThreadException();
2295 }
2296 }
2297
2298 public void parkVirtualThread(long nanos) {
2299 Thread thread = Thread.currentThread();
2300 if (thread instanceof BaseVirtualThread vthread) {
2301 vthread.parkNanos(nanos);
2302 } else {
2303 throw new WrongThreadException();
2304 }
2305 }
2306
2307 public void unparkVirtualThread(Thread thread) {
2308 if (thread instanceof BaseVirtualThread vthread) {
2309 vthread.unpark();
2310 } else {
2311 throw new WrongThreadException();
2312 }
2313 }
2314
2315 public Executor virtualThreadDefaultScheduler() {
2316 return VirtualThread.defaultScheduler();
2317 }
2318
2319 public StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
2320 ContinuationScope contScope,
2321 Continuation continuation) {
2322 return StackWalker.newInstance(options, null, contScope, continuation);
2323 }
2324
2325 public String getLoaderNameID(ClassLoader loader) {
2326 return loader != null ? loader.nameAndId() : "null";
2327 }
2328
2329 @Override
2330 public void copyToSegmentRaw(String string, MemorySegment segment, long offset) {
2331 string.copyToSegmentRaw(segment, offset);
2332 }
2333
2334 @Override
2335 public boolean bytesCompatible(String string, Charset charset) {
2336 return string.bytesCompatible(charset);
2337 }
2338 });
2339 }
2340 }