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.ClassFileFormatVersion;
43 import java.lang.reflect.Executable;
44 import java.lang.reflect.Method;
45 import java.net.URI;
46 import java.nio.channels.Channel;
47 import java.nio.channels.spi.SelectorProvider;
48 import java.nio.charset.CharacterCodingException;
49 import java.nio.charset.Charset;
50 import java.security.ProtectionDomain;
51 import java.util.List;
52 import java.util.Locale;
53 import java.util.Map;
54 import java.util.Objects;
55 import java.util.Properties;
56 import java.util.ResourceBundle;
57 import java.util.Set;
58 import java.util.concurrent.Executor;
59 import java.util.concurrent.ScheduledExecutorService;
60 import java.util.function.Supplier;
61 import java.util.concurrent.ConcurrentHashMap;
62 import java.util.stream.Stream;
63
64 import jdk.internal.javac.Restricted;
65 import jdk.internal.loader.NativeLibraries;
66 import jdk.internal.logger.LoggerFinderLoader.TemporaryLoggerFinder;
67 import jdk.internal.misc.Blocker;
68 import jdk.internal.misc.CarrierThreadLocal;
69 import jdk.internal.util.StaticProperty;
70 import jdk.internal.module.ModuleBootstrap;
71 import jdk.internal.module.ServicesCatalog;
72 import jdk.internal.reflect.CallerSensitive;
73 import jdk.internal.reflect.Reflection;
74 import jdk.internal.access.JavaLangAccess;
75 import jdk.internal.access.SharedSecrets;
76 import jdk.internal.logger.LoggerFinderLoader;
77 import jdk.internal.logger.LazyLoggers;
78 import jdk.internal.logger.LocalizedLoggerWrapper;
79 import jdk.internal.misc.VM;
80 import jdk.internal.util.SystemProps;
81 import jdk.internal.vm.Continuation;
82 import jdk.internal.vm.ContinuationScope;
83 import jdk.internal.vm.StackableScope;
84 import jdk.internal.vm.ThreadContainer;
85 import jdk.internal.vm.annotation.IntrinsicCandidate;
86 import jdk.internal.vm.annotation.Stable;
87 import sun.reflect.annotation.AnnotationType;
88 import sun.nio.ch.Interruptible;
89 import sun.nio.cs.UTF_8;
90
91 /**
92 * The {@code System} class contains several useful class fields
93 * and methods. It cannot be instantiated.
94 *
95 * Among the facilities provided by the {@code System} class
96 * are standard input, standard output, and error output streams;
97 * access to externally defined properties and environment
98 * variables; a means of loading files and libraries; and a utility
99 * method for quickly copying a portion of an array.
100 *
101 * @since 1.0
102 */
103 public final class System {
104 /* Register the natives via the static initializer.
105 *
106 * The VM will invoke the initPhase1 method to complete the initialization
107 * of this class separate from <clinit>.
108 */
109 private static native void registerNatives();
110 static {
111 registerNatives();
112 }
113
114 /** Don't let anyone instantiate this class */
115 private System() {
116 }
117
118 /**
119 * The "standard" input stream. This stream is already
120 * open and ready to supply input data. This stream
121 * corresponds to keyboard input or another input source specified by
122 * the host environment or user. Applications should use the encoding
123 * specified by the {@link ##stdin.encoding stdin.encoding} property
124 * to convert input bytes to character data.
125 *
126 * @apiNote
127 * The typical approach to read character data is to wrap {@code System.in}
128 * within the object that handles character encoding. After this is done,
129 * subsequent reading should use only the wrapper object; continuing to
130 * operate directly on {@code System.in} results in unspecified behavior.
131 * <p>
132 * Here are two common examples. Using an {@link java.io.InputStreamReader
133 * InputStreamReader}:
134 * {@snippet lang=java :
135 * new InputStreamReader(System.in, System.getProperty("stdin.encoding"));
136 * }
137 * Or using a {@link java.util.Scanner Scanner}:
138 * {@snippet lang=java :
139 * new Scanner(System.in, System.getProperty("stdin.encoding"));
140 * }
141 * <p>
142 * For handling interactive input, consider using {@link Console}.
143 *
144 * @see Console
145 * @see ##stdin.encoding stdin.encoding
146 */
147 public static final InputStream in = null;
148
149 /**
150 * The "standard" output stream. This stream is already
151 * open and ready to accept output data. Typically this stream
152 * corresponds to display output or another output destination
153 * specified by the host environment or user. The encoding used
154 * in the conversion from characters to bytes is equivalent to
155 * {@link ##stdout.encoding stdout.encoding}.
156 * <p>
157 * For simple stand-alone Java applications, a typical way to write
158 * a line of output data is:
159 * <blockquote><pre>
160 * System.out.println(data)
161 * </pre></blockquote>
162 * <p>
163 * See the {@code println} methods in class {@code PrintStream}.
164 *
165 * @see java.io.PrintStream#println()
166 * @see java.io.PrintStream#println(boolean)
167 * @see java.io.PrintStream#println(char)
168 * @see java.io.PrintStream#println(char[])
169 * @see java.io.PrintStream#println(double)
170 * @see java.io.PrintStream#println(float)
171 * @see java.io.PrintStream#println(int)
172 * @see java.io.PrintStream#println(long)
173 * @see java.io.PrintStream#println(java.lang.Object)
174 * @see java.io.PrintStream#println(java.lang.String)
175 * @see ##stdout.encoding stdout.encoding
176 */
177 public static final PrintStream out = null;
178
179 /**
180 * The "standard" error output stream. This stream is already
181 * open and ready to accept output data.
182 * <p>
183 * Typically this stream corresponds to display output or another
184 * output destination specified by the host environment or user. By
185 * convention, this output stream is used to display error messages
186 * or other information that should come to the immediate attention
187 * of a user even if the principal output stream, the value of the
188 * variable {@code out}, has been redirected to a file or other
189 * destination that is typically not continuously monitored.
190 * The encoding used in the conversion from characters to bytes is
191 * equivalent to {@link ##stderr.encoding stderr.encoding}.
192 *
193 * @see ##stderr.encoding stderr.encoding
194 */
195 public static final PrintStream err = null;
196
197 // Initial values of System.in and System.err, set in initPhase1().
198 private static @Stable InputStream initialIn;
199 private static @Stable PrintStream initialErr;
200
201 // `sun.jnu.encoding` if it is not supported. Otherwise null.
202 // It is initialized in `initPhase1()` before any charset providers
203 // are initialized.
204 private static String notSupportedJnuEncoding;
205
206 /**
207 * Reassigns the "standard" input stream.
208 *
209 * @param in the new standard input stream.
210 *
211 * @since 1.1
212 */
213 public static void setIn(InputStream in) {
214 setIn0(in);
215 }
216
217 /**
218 * Reassigns the "standard" output stream.
219 *
220 * @param out the new standard output stream
221 *
222 * @since 1.1
223 */
224 public static void setOut(PrintStream out) {
225 setOut0(out);
226 }
227
228 /**
229 * Reassigns the "standard" error output stream.
230 *
231 * @param err the new standard error output stream.
232 *
233 * @since 1.1
234 */
235 public static void setErr(PrintStream err) {
236 setErr0(err);
237 }
238
239 private static volatile Console cons;
240
241 /**
242 * Returns the unique {@link java.io.Console Console} object associated
243 * with the current Java virtual machine, if any.
244 *
245 * @return The system console, if any, otherwise {@code null}.
246 *
247 * @since 1.6
248 */
249 public static Console console() {
250 Console c;
251 if ((c = cons) == null) {
252 synchronized (System.class) {
253 if ((c = cons) == null) {
254 cons = c = SharedSecrets.getJavaIOAccess().console();
255 }
256 }
257 }
258 return c;
259 }
260
261 /**
262 * Returns the channel inherited from the entity that created this
263 * Java virtual machine.
264 *
265 * This method returns the channel obtained by invoking the
266 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
267 * inheritedChannel} method of the system-wide default
268 * {@link java.nio.channels.spi.SelectorProvider} object.
269 *
270 * <p> In addition to the network-oriented channels described in
271 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
272 * inheritedChannel}, this method may return other kinds of
273 * channels in the future.
274 *
275 * @return The inherited channel, if any, otherwise {@code null}.
276 *
277 * @throws IOException
278 * If an I/O error occurs
279 *
280 * @since 1.5
281 */
282 public static Channel inheritedChannel() throws IOException {
283 return SelectorProvider.provider().inheritedChannel();
284 }
285
286 private static native void setIn0(InputStream in);
287 private static native void setOut0(PrintStream out);
288 private static native void setErr0(PrintStream err);
289
290 /**
291 * Throws {@code UnsupportedOperationException}. Setting a security manager
292 * is not supported.
293 *
294 * @param sm ignored
295 * @throws UnsupportedOperationException always
296 * @see #getSecurityManager
297 * @deprecated This method originally set
298 * {@linkplain SecurityManager the system-wide Security Manager}.
299 * Setting a Security Manager is no longer supported. There is no
300 * replacement for the Security Manager or this method.
301 */
302 @Deprecated(since="17", forRemoval=true)
303 public static void setSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
304 throw new UnsupportedOperationException(
305 "Setting a Security Manager is not supported");
306 }
307
308 /**
309 * Returns {@code null}. Setting a security manager is not supported.
310 *
311 * @return {@code null}
312 * @see #setSecurityManager
313 * @deprecated This method originally returned
314 * {@linkplain SecurityManager the system-wide Security Manager}.
315 * Setting a Security Manager is no longer supported. There is no
316 * replacement for the Security Manager or this method.
317 */
318 @SuppressWarnings("removal")
319 @Deprecated(since="17", forRemoval=true)
320 public static SecurityManager getSecurityManager() {
321 return null;
322 }
323
324 /**
325 * Returns the current time in milliseconds. Note that
326 * while the unit of time of the return value is a millisecond,
327 * the granularity of the value depends on the underlying
328 * operating system and may be larger. For example, many
329 * operating systems measure time in units of tens of
330 * milliseconds.
331 *
332 * <p> See the description of the class {@code Date} for
333 * a discussion of slight discrepancies that may arise between
334 * "computer time" and coordinated universal time (UTC).
335 *
336 * @return the difference, measured in milliseconds, between
337 * the current time and midnight, January 1, 1970 UTC.
338 * @see java.util.Date
339 */
340 @IntrinsicCandidate
341 public static native long currentTimeMillis();
342
343 /**
344 * Returns the current value of the running Java Virtual Machine's
345 * high-resolution time source, in nanoseconds.
346 *
347 * This method can only be used to measure elapsed time and is
348 * not related to any other notion of system or wall-clock time.
349 * The value returned represents nanoseconds since some fixed but
350 * arbitrary <i>origin</i> time (perhaps in the future, so values
351 * may be negative). The same origin is used by all invocations of
352 * this method in an instance of a Java virtual machine; other
353 * virtual machine instances are likely to use a different origin.
354 *
355 * <p>This method provides nanosecond precision, but not necessarily
356 * nanosecond resolution (that is, how frequently the value changes)
357 * - no guarantees are made except that the resolution is at least as
358 * good as that of {@link #currentTimeMillis()}.
359 *
360 * <p>Differences in successive calls that span greater than
361 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
362 * correctly compute elapsed time due to numerical overflow.
363 *
364 * <p>The values returned by this method become meaningful only when
365 * the difference between two such values, obtained within the same
366 * instance of a Java virtual machine, is computed.
367 *
368 * <p>For example, to measure how long some code takes to execute:
369 * <pre> {@code
370 * long startTime = System.nanoTime();
371 * // ... the code being measured ...
372 * long elapsedNanos = System.nanoTime() - startTime;}</pre>
373 *
374 * <p>To compare elapsed time against a timeout, use <pre> {@code
375 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
376 * instead of <pre> {@code
377 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
378 * because of the possibility of numerical overflow.
379 *
380 * @return the current value of the running Java Virtual Machine's
381 * high-resolution time source, in nanoseconds
382 * @since 1.5
383 */
384 @IntrinsicCandidate
385 public static native long nanoTime();
386
387 /**
388 * Copies an array from the specified source array, beginning at the
389 * specified position, to the specified position of the destination array.
390 * A subsequence of array components are copied from the source
391 * array referenced by {@code src} to the destination array
392 * referenced by {@code dest}. The number of components copied is
393 * equal to the {@code length} argument. The components at
394 * positions {@code srcPos} through
395 * {@code srcPos+length-1} in the source array are copied into
396 * positions {@code destPos} through
397 * {@code destPos+length-1}, respectively, of the destination
398 * array.
399 * <p>
400 * If the {@code src} and {@code dest} arguments refer to the
401 * same array object, then the copying is performed as if the
402 * components at positions {@code srcPos} through
403 * {@code srcPos+length-1} were first copied to a temporary
404 * array with {@code length} components and then the contents of
405 * the temporary array were copied into positions
406 * {@code destPos} through {@code destPos+length-1} of the
407 * destination array.
408 * <p>
409 * If {@code dest} is {@code null}, then a
410 * {@code NullPointerException} is thrown.
411 * <p>
412 * If {@code src} is {@code null}, then a
413 * {@code NullPointerException} is thrown and the destination
414 * array is not modified.
415 * <p>
416 * Otherwise, if any of the following is true, an
417 * {@code ArrayStoreException} is thrown and the destination is
418 * not modified:
419 * <ul>
420 * <li>The {@code src} argument refers to an object that is not an
421 * array.
422 * <li>The {@code dest} argument refers to an object that is not an
423 * array.
424 * <li>The {@code src} argument and {@code dest} argument refer
425 * to arrays whose component types are different primitive types.
426 * <li>The {@code src} argument refers to an array with a primitive
427 * component type and the {@code dest} argument refers to an array
428 * with a reference component type.
429 * <li>The {@code src} argument refers to an array with a reference
430 * component type and the {@code dest} argument refers to an array
431 * with a primitive component type.
432 * </ul>
433 * <p>
434 * Otherwise, if any of the following is true, an
435 * {@code IndexOutOfBoundsException} is
436 * thrown and the destination is not modified:
437 * <ul>
438 * <li>The {@code srcPos} argument is negative.
439 * <li>The {@code destPos} argument is negative.
440 * <li>The {@code length} argument is negative.
441 * <li>{@code srcPos+length} is greater than
442 * {@code src.length}, the length of the source array.
443 * <li>{@code destPos+length} is greater than
444 * {@code dest.length}, the length of the destination array.
445 * </ul>
446 * <p>
447 * Otherwise, if any actual component of the source array from
448 * position {@code srcPos} through
449 * {@code srcPos+length-1} cannot be converted to the component
450 * type of the destination array by assignment conversion, an
451 * {@code ArrayStoreException} is thrown. In this case, let
452 * <b><i>k</i></b> be the smallest nonnegative integer less than
453 * length such that {@code src[srcPos+}<i>k</i>{@code ]}
454 * cannot be converted to the component type of the destination
455 * array; when the exception is thrown, source array components from
456 * positions {@code srcPos} through
457 * {@code srcPos+}<i>k</i>{@code -1}
458 * will already have been copied to destination array positions
459 * {@code destPos} through
460 * {@code destPos+}<i>k</I>{@code -1} and no other
461 * positions of the destination array will have been modified.
462 * (Because of the restrictions already itemized, this
463 * paragraph effectively applies only to the situation where both
464 * arrays have component types that are reference types.)
465 *
466 * @param src the source array.
467 * @param srcPos starting position in the source array.
468 * @param dest the destination array.
469 * @param destPos starting position in the destination data.
470 * @param length the number of array elements to be copied.
471 * @throws IndexOutOfBoundsException if copying would cause
472 * access of data outside array bounds.
473 * @throws ArrayStoreException if an element in the {@code src}
474 * array could not be stored into the {@code dest} array
475 * because of a type mismatch.
476 * @throws NullPointerException if either {@code src} or
477 * {@code dest} is {@code null}.
478 */
479 @IntrinsicCandidate
480 public static native void arraycopy(Object src, int srcPos,
481 Object dest, int destPos,
482 int length);
483
484 /**
485 * Returns the same hash code for the given object as
486 * would be returned by the default method hashCode(),
487 * whether or not the given object's class overrides
488 * hashCode().
489 * The hash code for the null reference is zero.
490 *
491 * <div class="preview-block">
492 * <div class="preview-comment">
493 * The "identity hash code" of a {@linkplain Class#isValue() value object}
494 * is computed by combining the identity hash codes of the value object's fields recursively.
495 * </div>
496 * </div>
497 * @apiNote
498 * <div class="preview-block">
499 * <div class="preview-comment">
500 * Note that, like ==, this hash code exposes information about a value object's
501 * private fields that might otherwise be hidden by an identity object.
502 * Developers should be cautious about storing sensitive secrets in value object fields.
503 * </div>
504 * </div>
505 *
506 * @param x object for which the hashCode is to be calculated
507 * @return the hashCode
508 * @since 1.1
509 * @see Object#hashCode
510 * @see java.util.Objects#hashCode(Object)
511 */
512 @IntrinsicCandidate
513 public static native int identityHashCode(Object x);
514
515 /**
516 * System properties.
517 *
518 * See {@linkplain #getProperties getProperties} for details.
519 */
520 private static Properties props;
521
522 /**
523 * Determines the current system properties.
524 * <p>
525 * The current set of system properties for use by the
526 * {@link #getProperty(String)} method is returned as a
527 * {@code Properties} object. If there is no current set of
528 * system properties, a set of system properties is first created and
529 * initialized. This set of system properties includes a value
530 * for each of the following keys unless the description of the associated
531 * value indicates that the value is optional.
532 * <table class="striped" style="text-align:left">
533 * <caption style="display:none">Shows property keys and associated values</caption>
534 * <thead>
535 * <tr><th scope="col">Key</th>
536 * <th scope="col">Description of Associated Value</th></tr>
537 * </thead>
538 * <tbody>
539 * <tr><th scope="row">{@systemProperty java.version}</th>
540 * <td>Java Runtime Environment version, which may be interpreted
541 * as a {@link Runtime.Version}</td></tr>
542 * <tr><th scope="row">{@systemProperty java.version.date}</th>
543 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
544 * format, which may be interpreted as a {@link
545 * java.time.LocalDate}</td></tr>
546 * <tr><th scope="row">{@systemProperty java.vendor}</th>
547 * <td>Java Runtime Environment vendor</td></tr>
548 * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
549 * <td>Java vendor URL</td></tr>
550 * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
551 * <td>Java vendor version <em>(optional)</em> </td></tr>
552 * <tr><th scope="row">{@systemProperty java.home}</th>
553 * <td>Java installation directory</td></tr>
554 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
555 * <td>Java Virtual Machine specification version, whose value is the
556 * {@linkplain Runtime.Version#feature feature} element of the
557 * {@linkplain Runtime#version() runtime version}</td></tr>
558 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
559 * <td>Java Virtual Machine specification vendor</td></tr>
560 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
561 * <td>Java Virtual Machine specification name</td></tr>
562 * <tr><th scope="row">{@systemProperty java.vm.version}</th>
563 * <td>Java Virtual Machine implementation version which may be
564 * interpreted as a {@link Runtime.Version}</td></tr>
565 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
566 * <td>Java Virtual Machine implementation vendor</td></tr>
567 * <tr><th scope="row">{@systemProperty java.vm.name}</th>
568 * <td>Java Virtual Machine implementation name</td></tr>
569 * <tr><th scope="row">{@systemProperty java.specification.version}</th>
570 * <td>Java Runtime Environment specification version, whose value is
571 * the {@linkplain Runtime.Version#feature feature} element of the
572 * {@linkplain Runtime#version() runtime version}</td></tr>
573 * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
574 * <td>Java Runtime Environment specification maintenance version,
575 * may be interpreted as a positive integer <em>(optional, see below)</em></td></tr>
576 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
577 * <td>Java Runtime Environment specification vendor</td></tr>
578 * <tr><th scope="row">{@systemProperty java.specification.name}</th>
579 * <td>Java Runtime Environment specification name</td></tr>
580 * <tr><th scope="row">{@systemProperty java.class.version}</th>
581 * <td>{@linkplain java.lang.reflect.ClassFileFormatVersion#latest() Latest}
582 * Java class file format version recognized by the Java runtime as {@code "MAJOR.MINOR"}
583 * where {@link java.lang.reflect.ClassFileFormatVersion#major() MAJOR} and {@code MINOR}
584 * are both formatted as decimal integers</td></tr>
585 * <tr><th scope="row">{@systemProperty java.class.path}</th>
586 * <td>Java class path (refer to
587 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
588 * <tr><th scope="row">{@systemProperty java.library.path}</th>
589 * <td>List of paths to search when loading libraries</td></tr>
590 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
591 * <td>Default temp file path</td></tr>
592 * <tr><th scope="row">{@systemProperty os.name}</th>
593 * <td>Operating system name</td></tr>
594 * <tr><th scope="row">{@systemProperty os.arch}</th>
595 * <td>Operating system architecture</td></tr>
596 * <tr><th scope="row">{@systemProperty os.version}</th>
597 * <td>Operating system version</td></tr>
598 * <tr><th scope="row">{@systemProperty file.separator}</th>
599 * <td>File separator ("/" on UNIX)</td></tr>
600 * <tr><th scope="row">{@systemProperty path.separator}</th>
601 * <td>Path separator (":" on UNIX)</td></tr>
602 * <tr><th scope="row">{@systemProperty line.separator}</th>
603 * <td>Line separator ("\n" on UNIX)</td></tr>
604 * <tr><th scope="row">{@systemProperty user.name}</th>
605 * <td>User's account name</td></tr>
606 * <tr><th scope="row">{@systemProperty user.home}</th>
607 * <td>User's home directory</td></tr>
608 * <tr><th scope="row">{@systemProperty user.dir}</th>
609 * <td>User's current working directory</td></tr>
610 * <tr><th scope="row">{@systemProperty native.encoding}</th>
611 * <td>Character encoding name derived from the host environment and
612 * the user's settings. Setting this system property on the command line
613 * has no effect.</td></tr>
614 * <tr><th scope="row">{@systemProperty stdin.encoding}</th>
615 * <td>Character encoding name for {@link System#in System.in}.
616 * The Java runtime can be started with the system property set to {@code UTF-8}.
617 * Starting it with the property set to another value results in unspecified behavior.
618 * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
619 * <td>Character encoding name for {@link System#out System.out} and
620 * {@link System#console() System.console()}.
621 * The Java runtime can be started with the system property set to {@code UTF-8}.
622 * Starting it with the property set to another value results in unspecified behavior.
623 * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
624 * <td>Character encoding name for {@link System#err System.err}.
625 * The Java runtime can be started with the system property set to {@code UTF-8}.
626 * Starting it with the property set to another value results in unspecified behavior.
627 * </tbody>
628 * </table>
629 * <p>
630 * The {@code java.specification.maintenance.version} property is
631 * defined if the specification implemented by this runtime at the
632 * time of its construction had undergone a <a
633 * href="https://jcp.org/en/procedures/jcp2#3.6.4">maintenance
634 * release</a>. When defined, its value identifies that
635 * maintenance release. To indicate the first maintenance release
636 * this property will have the value {@code "1"}, to indicate the
637 * second maintenance release this property will have the value
638 * {@code "2"}, and so on.
639 * <p>
640 * Multiple paths in a system property value are separated by the path
641 * separator character of the platform.
642 * <p>
643 * Additional locale-related system properties defined by the
644 * {@link Locale##default_locale Default Locale} section in the {@code Locale}
645 * class description may also be obtained with this method.
646 *
647 * @apiNote
648 * <strong>Changing a standard system property may have unpredictable results
649 * unless otherwise specified.</strong>
650 * Property values may be cached during initialization or on first use.
651 * Setting a standard property after initialization using {@link #getProperties()},
652 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
653 * {@link #clearProperty(String)} may not have the desired effect.
654 *
655 * @implNote
656 * In addition to the standard system properties, the system
657 * properties may include the following keys:
658 * <table class="striped">
659 * <caption style="display:none">Shows property keys and associated values</caption>
660 * <thead>
661 * <tr><th scope="col">Key</th>
662 * <th scope="col">Description of Associated Value</th></tr>
663 * </thead>
664 * <tbody>
665 * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
666 * <td>The application module path</td></tr>
667 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
668 * <td>The upgrade module path</td></tr>
669 * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
670 * <td>The module name of the initial/main module</td></tr>
671 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
672 * <td>The main class name of the initial module</td></tr>
673 * <tr><th scope="row">{@systemProperty file.encoding}</th>
674 * <td>The name of the default charset, defaults to {@code UTF-8}.
675 * The property may be set on the command line to the value
676 * {@code UTF-8} or {@code COMPAT}. If set on the command line to
677 * the value {@code COMPAT} then the value is replaced with the
678 * value of the {@code native.encoding} property during startup.
679 * Setting the property to a value other than {@code UTF-8} or
680 * {@code COMPAT} results in unspecified behavior.
681 * </td></tr>
682 * </tbody>
683 * </table>
684 *
685 * @return the system properties
686 * @see #setProperties
687 * @see java.util.Properties
688 */
689 public static Properties getProperties() {
690 return props;
691 }
692
693 /**
694 * Returns the system-dependent line separator string. It always
695 * returns the same value - the initial value of the {@linkplain
696 * #getProperty(String) system property} {@code line.separator}.
697 *
698 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
699 * Windows systems it returns {@code "\r\n"}.
700 *
701 * @return the system-dependent line separator string
702 * @since 1.7
703 */
704 public static String lineSeparator() {
705 return lineSeparator;
706 }
707
708 private static String lineSeparator;
709
710 /**
711 * Sets the system properties to the {@code Properties} argument.
712 * <p>
713 * The argument becomes the current set of system properties for use
714 * by the {@link #getProperty(String)} method. If the argument is
715 * {@code null}, then the current set of system properties is
716 * forgotten.
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 props the new system properties.
724 * @see #getProperties
725 * @see java.util.Properties
726 */
727 public static void setProperties(Properties props) {
728 if (props == null) {
729 Map<String, String> tempProps = SystemProps.initProperties();
730 VersionProps.init(tempProps);
731 props = createProperties(tempProps);
732 }
733 System.props = props;
734 }
735
736 /**
737 * Gets the system property indicated by the specified key.
738 * <p>
739 * If there is no current set of system properties, a set of system
740 * properties is first created and initialized in the same manner as
741 * for the {@code getProperties} method.
742 *
743 * @apiNote
744 * <strong>Changing a standard system property may have unpredictable results
745 * unless otherwise specified</strong>.
746 * See {@linkplain #getProperties getProperties} for details.
747 *
748 * @param key the name of the system property.
749 * @return the string value of the system property,
750 * or {@code null} if there is no property with that key.
751 *
752 * @throws NullPointerException if {@code key} is {@code null}.
753 * @throws IllegalArgumentException if {@code key} is empty.
754 * @see #setProperty
755 * @see java.lang.System#getProperties()
756 */
757 public static String getProperty(String key) {
758 checkKey(key);
759 return props.getProperty(key);
760 }
761
762 /**
763 * Gets the system property indicated by the specified key.
764 * <p>
765 * If there is no current set of system properties, a set of system
766 * properties is first created and initialized in the same manner as
767 * for the {@code getProperties} method.
768 *
769 * @param key the name of the system property.
770 * @param def a default value.
771 * @return the string value of the system property,
772 * or the default value if there is no property with that key.
773 *
774 * @throws NullPointerException if {@code key} is {@code null}.
775 * @throws IllegalArgumentException if {@code key} is empty.
776 * @see #setProperty
777 * @see java.lang.System#getProperties()
778 */
779 public static String getProperty(String key, String def) {
780 checkKey(key);
781 return props.getProperty(key, def);
782 }
783
784 /**
785 * Sets the system property indicated by the specified key.
786 *
787 * @apiNote
788 * <strong>Changing a standard system property may have unpredictable results
789 * unless otherwise specified</strong>.
790 * See {@linkplain #getProperties getProperties} for details.
791 *
792 * @param key the name of the system property.
793 * @param value the value of the system property.
794 * @return the previous value of the system property,
795 * or {@code null} if it did not have one.
796 *
797 * @throws NullPointerException if {@code key} or
798 * {@code value} is {@code null}.
799 * @throws IllegalArgumentException if {@code key} is empty.
800 * @see #getProperty
801 * @see java.lang.System#getProperty(java.lang.String)
802 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
803 * @since 1.2
804 */
805 public static String setProperty(String key, String value) {
806 checkKey(key);
807 return (String) props.setProperty(key, value);
808 }
809
810 /**
811 * Removes the system property indicated by the specified key.
812 *
813 * @apiNote
814 * <strong>Changing a standard system property may have unpredictable results
815 * unless otherwise specified</strong>.
816 * See {@linkplain #getProperties getProperties} method for details.
817 *
818 * @param key the name of the system property to be removed.
819 * @return the previous string value of the system property,
820 * or {@code null} if there was no property with that key.
821 *
822 * @throws NullPointerException if {@code key} is {@code null}.
823 * @throws IllegalArgumentException if {@code key} is empty.
824 * @see #getProperty
825 * @see #setProperty
826 * @see java.util.Properties
827 * @since 1.5
828 */
829 public static String clearProperty(String key) {
830 checkKey(key);
831 return (String) props.remove(key);
832 }
833
834 private static void checkKey(String key) {
835 if (key == null) {
836 throw new NullPointerException("key can't be null");
837 }
838 if (key.isEmpty()) {
839 throw new IllegalArgumentException("key can't be empty");
840 }
841 }
842
843 /**
844 * Gets the value of the specified environment variable. An
845 * environment variable is a system-dependent external named
846 * value.
847 *
848 * <p><a id="EnvironmentVSSystemProperties"><i>System
849 * properties</i> and <i>environment variables</i></a> are both
850 * conceptually mappings between names and values. Both
851 * mechanisms can be used to pass user-defined information to a
852 * Java process. Environment variables have a more global effect,
853 * because they are visible to all descendants of the process
854 * which defines them, not just the immediate Java subprocess.
855 * They can have subtly different semantics, such as case
856 * insensitivity, on different operating systems. For these
857 * reasons, environment variables are more likely to have
858 * unintended side effects. It is best to use system properties
859 * where possible. Environment variables should be used when a
860 * global effect is desired, or when an external system interface
861 * requires an environment variable (such as {@code PATH}).
862 *
863 * <p>On UNIX systems the alphabetic case of {@code name} is
864 * typically significant, while on Microsoft Windows systems it is
865 * typically not. For example, the expression
866 * {@code System.getenv("FOO").equals(System.getenv("foo"))}
867 * is likely to be true on Microsoft Windows.
868 *
869 * @param name the name of the environment variable
870 * @return the string value of the variable, or {@code null}
871 * if the variable is not defined in the system environment
872 * @throws NullPointerException if {@code name} is {@code null}
873 * @see #getenv()
874 * @see ProcessBuilder#environment()
875 */
876 public static String getenv(String name) {
877 return ProcessEnvironment.getenv(name);
878 }
879
880
881 /**
882 * Returns an unmodifiable string map view of the current system environment.
883 * The environment is a system-dependent mapping from names to
884 * values which is passed from parent to child processes.
885 *
886 * <p>If the system does not support environment variables, an
887 * empty map is returned.
888 *
889 * <p>The returned map will never contain null keys or values.
890 * Attempting to query the presence of a null key or value will
891 * throw a {@link NullPointerException}. Attempting to query
892 * the presence of a key or value which is not of type
893 * {@link String} will throw a {@link ClassCastException}.
894 *
895 * <p>The returned map and its collection views may not obey the
896 * general contract of the {@link Object#equals} and
897 * {@link Object#hashCode} methods.
898 *
899 * <p>The returned map is typically case-sensitive on all platforms.
900 *
901 * <p>When passing information to a Java subprocess,
902 * <a href=#EnvironmentVSSystemProperties>system properties</a>
903 * are generally preferred over environment variables.
904 *
905 * @return the environment as a map of variable names to values
906 * @see #getenv(String)
907 * @see ProcessBuilder#environment()
908 * @since 1.5
909 */
910 public static java.util.Map<String,String> getenv() {
911 return ProcessEnvironment.getenv();
912 }
913
914 /**
915 * {@code System.Logger} instances log messages that will be
916 * routed to the underlying logging framework the {@link System.LoggerFinder
917 * LoggerFinder} uses.
918 *
919 * {@code System.Logger} instances are typically obtained from
920 * the {@link java.lang.System System} class, by calling
921 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
922 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
923 * System.getLogger(loggerName, bundle)}.
924 *
925 * @see java.lang.System#getLogger(java.lang.String)
926 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
927 * @see java.lang.System.LoggerFinder
928 *
929 * @since 9
930 */
931 public interface Logger {
932
933 /**
934 * System {@linkplain Logger loggers} levels.
935 *
936 * A level has a {@linkplain #getName() name} and {@linkplain
937 * #getSeverity() severity}.
938 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
939 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
940 * by order of increasing severity.
941 * <br>
942 * {@link #ALL} and {@link #OFF}
943 * are simple markers with severities mapped respectively to
944 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
945 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
946 * <p>
947 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
948 * <p>
949 * {@linkplain System.Logger.Level System logger levels} are mapped to
950 * {@linkplain java.logging/java.util.logging.Level java.util.logging levels}
951 * of corresponding severity.
952 * <br>The mapping is as follows:
953 * <br><br>
954 * <table class="striped">
955 * <caption>System.Logger Severity Level Mapping</caption>
956 * <thead>
957 * <tr><th scope="col">System.Logger Levels</th>
958 * <th scope="col">java.util.logging Levels</th>
959 * </thead>
960 * <tbody>
961 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
962 * <td>{@link java.logging/java.util.logging.Level#ALL ALL}</td>
963 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
964 * <td>{@link java.logging/java.util.logging.Level#FINER FINER}</td>
965 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
966 * <td>{@link java.logging/java.util.logging.Level#FINE FINE}</td>
967 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
968 * <td>{@link java.logging/java.util.logging.Level#INFO INFO}</td>
969 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
970 * <td>{@link java.logging/java.util.logging.Level#WARNING WARNING}</td>
971 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
972 * <td>{@link java.logging/java.util.logging.Level#SEVERE SEVERE}</td>
973 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
974 * <td>{@link java.logging/java.util.logging.Level#OFF OFF}</td>
975 * </tbody>
976 * </table>
977 *
978 * @since 9
979 *
980 * @see java.lang.System.LoggerFinder
981 * @see java.lang.System.Logger
982 */
983 @SuppressWarnings("doclint:reference") // cross-module links
984 public enum Level {
985
986 // for convenience, we're reusing java.util.logging.Level int values
987 // the mapping logic in sun.util.logging.PlatformLogger depends
988 // on this.
989 /**
990 * A marker to indicate that all levels are enabled.
991 * This level {@linkplain #getSeverity() severity} is
992 * {@link Integer#MIN_VALUE}.
993 */
994 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
995 /**
996 * {@code TRACE} level: usually used to log diagnostic information.
997 * This level {@linkplain #getSeverity() severity} is
998 * {@code 400}.
999 */
1000 TRACE(400), // typically mapped to/from j.u.l.Level.FINER
1001 /**
1002 * {@code DEBUG} level: usually used to log debug information traces.
1003 * This level {@linkplain #getSeverity() severity} is
1004 * {@code 500}.
1005 */
1006 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
1007 /**
1008 * {@code INFO} level: usually used to log information messages.
1009 * This level {@linkplain #getSeverity() severity} is
1010 * {@code 800}.
1011 */
1012 INFO(800), // typically mapped to/from j.u.l.Level.INFO
1013 /**
1014 * {@code WARNING} level: usually used to log warning messages.
1015 * This level {@linkplain #getSeverity() severity} is
1016 * {@code 900}.
1017 */
1018 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
1019 /**
1020 * {@code ERROR} level: usually used to log error messages.
1021 * This level {@linkplain #getSeverity() severity} is
1022 * {@code 1000}.
1023 */
1024 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
1025 /**
1026 * A marker to indicate that all levels are disabled.
1027 * This level {@linkplain #getSeverity() severity} is
1028 * {@link Integer#MAX_VALUE}.
1029 */
1030 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
1031
1032 private final int severity;
1033
1034 private Level(int severity) {
1035 this.severity = severity;
1036 }
1037
1038 /**
1039 * Returns the name of this level.
1040 * @return this level {@linkplain #name()}.
1041 */
1042 public final String getName() {
1043 return name();
1044 }
1045
1046 /**
1047 * Returns the severity of this level.
1048 * A higher severity means a more severe condition.
1049 * @return this level severity.
1050 */
1051 public final int getSeverity() {
1052 return severity;
1053 }
1054 }
1055
1056 /**
1057 * Returns the name of this logger.
1058 *
1059 * @return the logger name.
1060 */
1061 public String getName();
1062
1063 /**
1064 * Checks if a message of the given level would be logged by
1065 * this logger.
1066 *
1067 * @param level the log message level.
1068 * @return {@code true} if the given log message level is currently
1069 * being logged.
1070 *
1071 * @throws NullPointerException if {@code level} is {@code null}.
1072 */
1073 public boolean isLoggable(Level level);
1074
1075 /**
1076 * Logs a message.
1077 *
1078 * @implSpec The default implementation for this method calls
1079 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1080 *
1081 * @param level the log message level.
1082 * @param msg the string message (or a key in the message catalog, if
1083 * this logger is a {@link
1084 * LoggerFinder#getLocalizedLogger(java.lang.String,
1085 * java.util.ResourceBundle, java.lang.Module) localized logger});
1086 * can be {@code null}.
1087 *
1088 * @throws NullPointerException if {@code level} is {@code null}.
1089 */
1090 public default void log(Level level, String msg) {
1091 log(level, (ResourceBundle) null, msg, (Object[]) null);
1092 }
1093
1094 /**
1095 * Logs a lazily supplied message.
1096 *
1097 * If the logger is currently enabled for the given log message level
1098 * then a message is logged that is the result produced by the
1099 * given supplier function. Otherwise, the supplier 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, msgSupplier.get(), (Object[])null);}
1104 *
1105 * @param level the log message level.
1106 * @param msgSupplier a supplier function that produces a message.
1107 *
1108 * @throws NullPointerException if {@code level} is {@code null},
1109 * or {@code msgSupplier} is {@code null}.
1110 */
1111 public default void log(Level level, Supplier<String> msgSupplier) {
1112 Objects.requireNonNull(msgSupplier);
1113 if (isLoggable(Objects.requireNonNull(level))) {
1114 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1115 }
1116 }
1117
1118 /**
1119 * Logs a message produced from the given object.
1120 *
1121 * If the logger is currently enabled for the given log message level then
1122 * a message is logged that, by default, is the result produced from
1123 * calling toString on the given object.
1124 * Otherwise, the object is not operated on.
1125 *
1126 * @implSpec When logging is enabled for the given level, the default
1127 * implementation for this method calls
1128 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1129 *
1130 * @param level the log message level.
1131 * @param obj the object to log.
1132 *
1133 * @throws NullPointerException if {@code level} is {@code null}, or
1134 * {@code obj} is {@code null}.
1135 */
1136 public default void log(Level level, Object obj) {
1137 Objects.requireNonNull(obj);
1138 if (isLoggable(Objects.requireNonNull(level))) {
1139 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1140 }
1141 }
1142
1143 /**
1144 * Logs a message associated with a given throwable.
1145 *
1146 * @implSpec The default implementation for this method calls
1147 * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1148 *
1149 * @param level the log message level.
1150 * @param msg the string message (or a key in the message catalog, if
1151 * this logger is a {@link
1152 * LoggerFinder#getLocalizedLogger(java.lang.String,
1153 * java.util.ResourceBundle, java.lang.Module) localized logger});
1154 * can be {@code null}.
1155 * @param thrown a {@code Throwable} associated with the log message;
1156 * can be {@code null}.
1157 *
1158 * @throws NullPointerException if {@code level} is {@code null}.
1159 */
1160 public default void log(Level level, String msg, Throwable thrown) {
1161 this.log(level, null, msg, thrown);
1162 }
1163
1164 /**
1165 * Logs a lazily supplied message associated with a given throwable.
1166 *
1167 * If the logger is currently enabled for the given log message level
1168 * then a message is logged that is the result produced by the
1169 * given supplier function. Otherwise, the supplier is not operated on.
1170 *
1171 * @implSpec When logging is enabled for the given level, the default
1172 * implementation for this method calls
1173 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1174 *
1175 * @param level one of the log message level identifiers.
1176 * @param msgSupplier a supplier function that produces a message.
1177 * @param thrown a {@code Throwable} associated with log message;
1178 * can be {@code null}.
1179 *
1180 * @throws NullPointerException if {@code level} is {@code null}, or
1181 * {@code msgSupplier} is {@code null}.
1182 */
1183 public default void log(Level level, Supplier<String> msgSupplier,
1184 Throwable thrown) {
1185 Objects.requireNonNull(msgSupplier);
1186 if (isLoggable(Objects.requireNonNull(level))) {
1187 this.log(level, null, msgSupplier.get(), thrown);
1188 }
1189 }
1190
1191 /**
1192 * Logs a message with an optional list of parameters.
1193 *
1194 * @implSpec The default implementation for this method calls
1195 * {@code this.log(level, (ResourceBundle)null, format, params);}
1196 *
1197 * @param level one of the log message level identifiers.
1198 * @param format the string message format in {@link
1199 * java.text.MessageFormat} format, (or a key in the message
1200 * catalog, if this logger is a {@link
1201 * LoggerFinder#getLocalizedLogger(java.lang.String,
1202 * java.util.ResourceBundle, java.lang.Module) localized logger});
1203 * can be {@code null}.
1204 * @param params an optional list of parameters to the message (may be
1205 * none).
1206 *
1207 * @throws NullPointerException if {@code level} is {@code null}.
1208 */
1209 public default void log(Level level, String format, Object... params) {
1210 this.log(level, null, format, params);
1211 }
1212
1213 /**
1214 * Logs a localized message associated with a given throwable.
1215 *
1216 * If the given resource bundle is non-{@code null}, the {@code msg}
1217 * string is localized using the given resource bundle.
1218 * Otherwise the {@code msg} string is not localized.
1219 *
1220 * @param level the log message level.
1221 * @param bundle a resource bundle to localize {@code msg}; can be
1222 * {@code null}.
1223 * @param msg the string message (or a key in the message catalog,
1224 * if {@code bundle} is not {@code null}); can be {@code null}.
1225 * @param thrown a {@code Throwable} associated with the log message;
1226 * can be {@code null}.
1227 *
1228 * @throws NullPointerException if {@code level} is {@code null}.
1229 */
1230 public void log(Level level, ResourceBundle bundle, String msg,
1231 Throwable thrown);
1232
1233 /**
1234 * Logs a message with resource bundle and an optional list of
1235 * parameters.
1236 *
1237 * If the given resource bundle is non-{@code null}, the {@code format}
1238 * string is localized using the given resource bundle.
1239 * Otherwise the {@code format} string is not localized.
1240 *
1241 * @param level the log message level.
1242 * @param bundle a resource bundle to localize {@code format}; can be
1243 * {@code null}.
1244 * @param format the string message format in {@link
1245 * java.text.MessageFormat} format, (or a key in the message
1246 * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1247 * @param params an optional list of parameters to the message (may be
1248 * none).
1249 *
1250 * @throws NullPointerException if {@code level} is {@code null}.
1251 */
1252 public void log(Level level, ResourceBundle bundle, String format,
1253 Object... params);
1254 }
1255
1256 /**
1257 * The {@code LoggerFinder} service is responsible for creating, managing,
1258 * and configuring loggers to the underlying framework it uses.
1259 *
1260 * A logger finder is a concrete implementation of this class that has a
1261 * zero-argument constructor and implements the abstract methods defined
1262 * by this class.
1263 * The loggers returned from a logger finder are capable of routing log
1264 * messages to the logging backend this provider supports.
1265 * A given invocation of the Java Runtime maintains a single
1266 * system-wide LoggerFinder instance that is loaded as follows:
1267 * <ul>
1268 * <li>First it finds any custom {@code LoggerFinder} provider
1269 * using the {@link java.util.ServiceLoader} facility with the
1270 * {@linkplain ClassLoader#getSystemClassLoader() system class
1271 * loader}.</li>
1272 * <li>If no {@code LoggerFinder} provider is found, the system default
1273 * {@code LoggerFinder} implementation will be used.</li>
1274 * </ul>
1275 * <p>
1276 * An application can replace the logging backend
1277 * <i>even when the java.logging module is present</i>, by simply providing
1278 * and declaring an implementation of the {@link LoggerFinder} service.
1279 * <p>
1280 * <b>Default Implementation</b>
1281 * <p>
1282 * The system default {@code LoggerFinder} implementation uses
1283 * {@code java.util.logging} as the backend framework when the
1284 * {@code java.logging} module is present.
1285 * It returns a {@linkplain System.Logger logger} instance
1286 * that will route log messages to a {@link java.logging/java.util.logging.Logger
1287 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1288 * present, the default implementation will return a simple logger
1289 * instance that will route log messages of {@code INFO} level and above to
1290 * the console ({@code System.err}).
1291 * <p>
1292 * <b>Logging Configuration</b>
1293 * <p>
1294 * {@linkplain Logger Logger} instances obtained from the
1295 * {@code LoggerFinder} factory methods are not directly configurable by
1296 * the application. Configuration is the responsibility of the underlying
1297 * logging backend, and usually requires using APIs specific to that backend.
1298 * <p>For the default {@code LoggerFinder} implementation
1299 * using {@code java.util.logging} as its backend, refer to
1300 * {@link java.logging/java.util.logging java.util.logging} for logging configuration.
1301 * For the default {@code LoggerFinder} implementation returning simple loggers
1302 * when the {@code java.logging} module is absent, the configuration
1303 * is implementation dependent.
1304 * <p>
1305 * Usually an application that uses a logging framework will log messages
1306 * through a logger facade defined (or supported) by that framework.
1307 * Applications that wish to use an external framework should log
1308 * through the facade associated with that framework.
1309 * <p>
1310 * A system class that needs to log messages will typically obtain
1311 * a {@link System.Logger} instance to route messages to the logging
1312 * framework selected by the application.
1313 * <p>
1314 * Libraries and classes that only need loggers to produce log messages
1315 * should not attempt to configure loggers by themselves, as that
1316 * would make them dependent from a specific implementation of the
1317 * {@code LoggerFinder} service.
1318 * <p>
1319 * <b>Message Levels and Mapping to backend levels</b>
1320 * <p>
1321 * A logger finder is responsible for mapping from a {@code
1322 * System.Logger.Level} to a level supported by the logging backend it uses.
1323 * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1324 * maps {@code System.Logger} levels to
1325 * {@linkplain java.logging/java.util.logging.Level java.util.logging} levels
1326 * of corresponding severity - as described in {@link Logger.Level
1327 * Logger.Level}.
1328 *
1329 * @see java.lang.System
1330 * @see java.lang.System.Logger
1331 *
1332 * @since 9
1333 */
1334 @SuppressWarnings("doclint:reference") // cross-module links
1335 public abstract static class LoggerFinder {
1336
1337 /**
1338 * Creates a new instance of {@code LoggerFinder}.
1339 *
1340 * @implNote It is recommended that a {@code LoggerFinder} service
1341 * implementation does not perform any heavy initialization in its
1342 * constructor, in order to avoid possible risks of deadlock or class
1343 * loading cycles during the instantiation of the service provider.
1344 */
1345 protected LoggerFinder() {
1346 }
1347
1348 /**
1349 * Returns an instance of {@link Logger Logger}
1350 * for the given {@code module}.
1351 *
1352 * @param name the name of the logger.
1353 * @param module the module for which the logger is being requested.
1354 *
1355 * @return a {@link Logger logger} suitable for use within the given
1356 * module.
1357 * @throws NullPointerException if {@code name} is {@code null} or
1358 * {@code module} is {@code null}.
1359 */
1360 public abstract Logger getLogger(String name, Module module);
1361
1362 /**
1363 * Returns a localizable instance of {@link Logger Logger}
1364 * for the given {@code module}.
1365 * The returned logger will use the provided resource bundle for
1366 * message localization.
1367 *
1368 * @implSpec By default, this method calls {@link
1369 * #getLogger(java.lang.String, java.lang.Module)
1370 * this.getLogger(name, module)} to obtain a logger, then wraps that
1371 * logger in a {@link Logger} instance where all methods that do not
1372 * take a {@link ResourceBundle} as parameter are redirected to one
1373 * which does - passing the given {@code bundle} for
1374 * localization. So for instance, a call to {@link
1375 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1376 * will end up as a call to {@link
1377 * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1378 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1379 * logger instance.
1380 * Note however that by default, string messages returned by {@link
1381 * java.util.function.Supplier Supplier<String>} will not be
1382 * localized, as it is assumed that such strings are messages which are
1383 * already constructed, rather than keys in a resource bundle.
1384 * <p>
1385 * An implementation of {@code LoggerFinder} may override this method,
1386 * for example, when the underlying logging backend provides its own
1387 * mechanism for localizing log messages, then such a
1388 * {@code LoggerFinder} would be free to return a logger
1389 * that makes direct use of the mechanism provided by the backend.
1390 *
1391 * @param name the name of the logger.
1392 * @param bundle a resource bundle; can be {@code null}.
1393 * @param module the module for which the logger is being requested.
1394 * @return an instance of {@link Logger Logger} which will use the
1395 * provided resource bundle for message localization.
1396 *
1397 * @throws NullPointerException if {@code name} is {@code null} or
1398 * {@code module} is {@code null}.
1399 */
1400 public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1401 Module module) {
1402 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1403 }
1404
1405 /**
1406 * Returns the {@code LoggerFinder} instance. There is one
1407 * single system-wide {@code LoggerFinder} instance in
1408 * the Java Runtime. See the class specification of how the
1409 * {@link LoggerFinder LoggerFinder} implementation is located and
1410 * loaded.
1411 *
1412 * @return the {@link LoggerFinder LoggerFinder} instance.
1413 */
1414 public static LoggerFinder getLoggerFinder() {
1415 return accessProvider();
1416 }
1417
1418
1419 private static volatile LoggerFinder service;
1420 static LoggerFinder accessProvider() {
1421 // We do not need to synchronize: LoggerFinderLoader will
1422 // always return the same instance, so if we don't have it,
1423 // just fetch it again.
1424 LoggerFinder finder = service;
1425 if (finder == null) {
1426 finder = LoggerFinderLoader.getLoggerFinder();
1427 if (finder instanceof TemporaryLoggerFinder) return finder;
1428 service = finder;
1429 }
1430 return finder;
1431 }
1432
1433 }
1434
1435
1436 /**
1437 * Returns an instance of {@link Logger Logger} for the caller's
1438 * use.
1439 *
1440 * @implSpec
1441 * Instances returned by this method route messages to loggers
1442 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1443 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1444 * {@code module} is the caller's module.
1445 * In cases where {@code System.getLogger} is called from a context where
1446 * there is no caller frame on the stack (e.g when called directly
1447 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1448 * To obtain a logger in such a context, use an auxiliary class that will
1449 * implicitly be identified as the caller, or use the system {@link
1450 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1451 * Note that doing the latter may eagerly initialize the underlying
1452 * logging system.
1453 *
1454 * @apiNote
1455 * This method may defer calling the {@link
1456 * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1457 * LoggerFinder.getLogger} method to create an actual logger supplied by
1458 * the logging backend, for instance, to allow loggers to be obtained during
1459 * the system initialization time.
1460 *
1461 * @param name the name of the logger.
1462 * @return an instance of {@link Logger} that can be used by the calling
1463 * class.
1464 * @throws NullPointerException if {@code name} is {@code null}.
1465 * @throws IllegalCallerException if there is no Java caller frame on the
1466 * stack.
1467 *
1468 * @since 9
1469 */
1470 @CallerSensitive
1471 public static Logger getLogger(String name) {
1472 Objects.requireNonNull(name);
1473 final Class<?> caller = Reflection.getCallerClass();
1474 if (caller == null) {
1475 throw new IllegalCallerException("no caller frame");
1476 }
1477 return LazyLoggers.getLogger(name, caller.getModule());
1478 }
1479
1480 /**
1481 * Returns a localizable instance of {@link Logger
1482 * Logger} for the caller's use.
1483 * The returned logger will use the provided resource bundle for message
1484 * localization.
1485 *
1486 * @implSpec
1487 * The returned logger will perform message localization as specified
1488 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1489 * java.util.ResourceBundle, java.lang.Module)
1490 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1491 * {@code module} is the caller's module.
1492 * In cases where {@code System.getLogger} is called from a context where
1493 * there is no caller frame on the stack (e.g when called directly
1494 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1495 * To obtain a logger in such a context, use an auxiliary class that
1496 * will implicitly be identified as the caller, or use the system {@link
1497 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1498 * Note that doing the latter may eagerly initialize the underlying
1499 * logging system.
1500 *
1501 * @apiNote
1502 * This method is intended to be used after the system is fully initialized.
1503 * This method may trigger the immediate loading and initialization
1504 * of the {@link LoggerFinder} service, which may cause issues if the
1505 * Java Runtime is not ready to initialize the concrete service
1506 * implementation yet.
1507 * System classes which may be loaded early in the boot sequence and
1508 * need to log localized messages should create a logger using
1509 * {@link #getLogger(java.lang.String)} and then use the log methods that
1510 * take a resource bundle as parameter.
1511 *
1512 * @param name the name of the logger.
1513 * @param bundle a resource bundle.
1514 * @return an instance of {@link Logger} which will use the provided
1515 * resource bundle for message localization.
1516 * @throws NullPointerException if {@code name} is {@code null} or
1517 * {@code bundle} is {@code null}.
1518 * @throws IllegalCallerException if there is no Java caller frame on the
1519 * stack.
1520 *
1521 * @since 9
1522 */
1523 @CallerSensitive
1524 public static Logger getLogger(String name, ResourceBundle bundle) {
1525 final ResourceBundle rb = Objects.requireNonNull(bundle);
1526 Objects.requireNonNull(name);
1527 final Class<?> caller = Reflection.getCallerClass();
1528 if (caller == null) {
1529 throw new IllegalCallerException("no caller frame");
1530 }
1531 return LoggerFinder.accessProvider()
1532 .getLocalizedLogger(name, rb, caller.getModule());
1533 }
1534
1535 /**
1536 * Initiates the {@linkplain Runtime##shutdown shutdown sequence} of the Java Virtual
1537 * Machine. This method initiates the shutdown sequence (if it is not already initiated)
1538 * and then blocks indefinitely. This method neither returns nor throws an exception;
1539 * that is, it does not complete either normally or abruptly.
1540 * <p>
1541 * The argument serves as a status code. By convention, a nonzero status code
1542 * indicates abnormal termination.
1543 * <p>
1544 * The call {@code System.exit(n)} is effectively equivalent to the call:
1545 * {@snippet :
1546 * Runtime.getRuntime().exit(n)
1547 * }
1548 *
1549 * @implNote
1550 * The initiation of the shutdown sequence is logged by {@link Runtime#exit(int)}.
1551 *
1552 * @param status exit status.
1553 * @see java.lang.Runtime#exit(int)
1554 */
1555 public static void exit(int status) {
1556 Runtime.getRuntime().exit(status);
1557 }
1558
1559 /**
1560 * Runs the garbage collector in the Java Virtual Machine.
1561 * <p>
1562 * Calling the {@code gc} method suggests that the Java Virtual Machine
1563 * expend effort toward recycling unused objects in order to
1564 * make the memory they currently occupy available for reuse
1565 * by the Java Virtual Machine.
1566 * When control returns from the method call, the Java Virtual Machine
1567 * has made a best effort to reclaim space from all unused objects.
1568 * There is no guarantee that this effort will recycle any particular
1569 * number of unused objects, reclaim any particular amount of space, or
1570 * complete at any particular time, if at all, before the method returns or ever.
1571 * There is also no guarantee that this effort will determine
1572 * the change of reachability in any particular number of objects,
1573 * or that any particular number of {@link java.lang.ref.Reference Reference}
1574 * objects will be cleared and enqueued.
1575 *
1576 * <p>
1577 * The call {@code System.gc()} is effectively equivalent to the
1578 * call:
1579 * <blockquote><pre>
1580 * Runtime.getRuntime().gc()
1581 * </pre></blockquote>
1582 *
1583 * @see java.lang.Runtime#gc()
1584 */
1585 public static void gc() {
1586 Runtime.getRuntime().gc();
1587 }
1588
1589 /**
1590 * Runs the finalization methods of any objects pending finalization.
1591 *
1592 * Calling this method suggests that the Java Virtual Machine expend
1593 * effort toward running the {@code finalize} methods of objects
1594 * that have been found to be discarded but whose {@code finalize}
1595 * methods have not yet been run. When control returns from the
1596 * method call, the Java Virtual Machine has made a best effort to
1597 * complete all outstanding finalizations.
1598 * <p>
1599 * The call {@code System.runFinalization()} is effectively
1600 * equivalent to the call:
1601 * <blockquote><pre>
1602 * Runtime.getRuntime().runFinalization()
1603 * </pre></blockquote>
1604 *
1605 * @deprecated Finalization has been deprecated for removal. See
1606 * {@link java.lang.Object#finalize} for background information and details
1607 * about migration options.
1608 * <p>
1609 * When running in a JVM in which finalization has been disabled or removed,
1610 * no objects will be pending finalization, so this method does nothing.
1611 *
1612 * @see java.lang.Runtime#runFinalization()
1613 * @jls 12.6 Finalization of Class Instances
1614 */
1615 @Deprecated(since="18", forRemoval=true)
1616 @SuppressWarnings("removal")
1617 public static void runFinalization() {
1618 Runtime.getRuntime().runFinalization();
1619 }
1620
1621 /**
1622 * Loads the native library specified by the filename argument. The filename
1623 * argument must be an absolute path name.
1624 *
1625 * If the filename argument, when stripped of any platform-specific library
1626 * prefix, path, and file extension, indicates a library whose name is,
1627 * for example, L, and a native library called L is statically linked
1628 * with the VM, then the JNI_OnLoad_L function exported by the library
1629 * is invoked rather than attempting to load a dynamic library.
1630 * A filename matching the argument does not have to exist in the
1631 * file system.
1632 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1633 * for more details.
1634 *
1635 * Otherwise, the filename argument is mapped to a native library image in
1636 * an implementation-dependent manner.
1637 *
1638 * <p>
1639 * The call {@code System.load(name)} is effectively equivalent
1640 * to the call:
1641 * <blockquote><pre>
1642 * Runtime.getRuntime().load(name)
1643 * </pre></blockquote>
1644 *
1645 * @param filename the file to load.
1646 * @throws UnsatisfiedLinkError if either the filename is not an
1647 * absolute path name, the native library is not statically
1648 * linked with the VM, or the library cannot be mapped to
1649 * a native library image by the host system.
1650 * @throws NullPointerException if {@code filename} is {@code null}
1651 * @throws IllegalCallerException if the caller is in a module that
1652 * does not have native access enabled.
1653 *
1654 * @spec jni/index.html Java Native Interface Specification
1655 * @see java.lang.Runtime#load(java.lang.String)
1656 */
1657 @CallerSensitive
1658 @Restricted
1659 public static void load(String filename) {
1660 Class<?> caller = Reflection.getCallerClass();
1661 Reflection.ensureNativeAccess(caller, System.class, "load", false);
1662 Runtime.getRuntime().load0(caller, filename);
1663 }
1664
1665 /**
1666 * Loads the native library specified by the {@code libname}
1667 * argument. The {@code libname} argument must not contain any platform
1668 * specific prefix, file extension or path. If a native library
1669 * called {@code libname} is statically linked with the VM, then the
1670 * JNI_OnLoad_{@code libname} function exported by the library is invoked.
1671 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1672 * for more details.
1673 *
1674 * Otherwise, the libname argument is loaded from a system library
1675 * location and mapped to a native library image in an
1676 * implementation-dependent manner.
1677 * <p>
1678 * The call {@code System.loadLibrary(name)} is effectively
1679 * equivalent to the call
1680 * <blockquote><pre>
1681 * Runtime.getRuntime().loadLibrary(name)
1682 * </pre></blockquote>
1683 *
1684 * @param libname the name of the library.
1685 * @throws UnsatisfiedLinkError if either the libname argument
1686 * contains a file path, the native library is not statically
1687 * linked with the VM, or the library cannot be mapped to a
1688 * native library image by the host system.
1689 * @throws NullPointerException if {@code libname} is {@code null}
1690 * @throws IllegalCallerException if the caller is in a module that
1691 * does not have native access enabled.
1692 *
1693 * @spec jni/index.html Java Native Interface Specification
1694 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1695 */
1696 @CallerSensitive
1697 @Restricted
1698 public static void loadLibrary(String libname) {
1699 Class<?> caller = Reflection.getCallerClass();
1700 Reflection.ensureNativeAccess(caller, System.class, "loadLibrary", false);
1701 Runtime.getRuntime().loadLibrary0(caller, libname);
1702 }
1703
1704 /**
1705 * Maps a library name into a platform-specific string representing
1706 * a native library.
1707 *
1708 * @param libname the name of the library.
1709 * @return a platform-dependent native library name.
1710 * @throws NullPointerException if {@code libname} is {@code null}
1711 * @see java.lang.System#loadLibrary(java.lang.String)
1712 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1713 * @since 1.2
1714 */
1715 public static native String mapLibraryName(String libname);
1716
1717 /**
1718 * Create PrintStream for stdout/err based on encoding.
1719 */
1720 private static PrintStream newPrintStream(OutputStream out, String enc) {
1721 if (enc != null) {
1722 return new PrintStream(new BufferedOutputStream(out, 128), true,
1723 Charset.forName(enc, UTF_8.INSTANCE));
1724 }
1725 return new PrintStream(new BufferedOutputStream(out, 128), true);
1726 }
1727
1728 /**
1729 * Logs an exception/error at initialization time to stdout or stderr.
1730 *
1731 * @param printToStderr to print to stderr rather than stdout
1732 * @param printStackTrace to print the stack trace
1733 * @param msg the message to print before the exception, can be {@code null}
1734 * @param e the exception or error
1735 */
1736 private static void logInitException(boolean printToStderr,
1737 boolean printStackTrace,
1738 String msg,
1739 Throwable e) {
1740 if (VM.initLevel() < 1) {
1741 throw new InternalError("system classes not initialized");
1742 }
1743 PrintStream log = (printToStderr) ? err : out;
1744 if (msg != null) {
1745 log.println(msg);
1746 }
1747 if (printStackTrace) {
1748 e.printStackTrace(log);
1749 } else {
1750 log.println(e);
1751 for (Throwable suppressed : e.getSuppressed()) {
1752 log.println("Suppressed: " + suppressed);
1753 }
1754 Throwable cause = e.getCause();
1755 if (cause != null) {
1756 log.println("Caused by: " + cause);
1757 }
1758 }
1759 }
1760
1761 /**
1762 * Create the Properties object from a map - masking out system properties
1763 * that are not intended for public access.
1764 */
1765 private static Properties createProperties(Map<String, String> initialProps) {
1766 Properties properties = new Properties(initialProps.size());
1767 for (var entry : initialProps.entrySet()) {
1768 String prop = entry.getKey();
1769 switch (prop) {
1770 // Do not add private system properties to the Properties
1771 case "sun.nio.MaxDirectMemorySize":
1772 case "sun.nio.PageAlignDirectMemory":
1773 // used by java.lang.Integer.IntegerCache
1774 case "java.lang.Integer.IntegerCache.high":
1775 // used by sun.launcher.LauncherHelper
1776 case "sun.java.launcher.diag":
1777 // used by jdk.internal.loader.ClassLoaders
1778 case "jdk.boot.class.path.append":
1779 break;
1780 default:
1781 properties.put(prop, entry.getValue());
1782 }
1783 }
1784 return properties;
1785 }
1786
1787 /**
1788 * Initialize the system class. Called after thread initialization.
1789 */
1790 private static void initPhase1() {
1791
1792 // register the shared secrets - do this first, since SystemProps.initProperties
1793 // might initialize CharsetDecoders that rely on it
1794 setJavaLangAccess();
1795
1796 // VM might invoke JNU_NewStringPlatform() to set those encoding
1797 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1798 // during "props" initialization.
1799 // The charset is initialized in System.c and does not depend on the Properties.
1800 Map<String, String> tempProps = SystemProps.initProperties();
1801 VersionProps.init(tempProps);
1802
1803 // There are certain system configurations that may be controlled by
1804 // VM options such as the maximum amount of direct memory and
1805 // Integer cache size used to support the object identity semantics
1806 // of autoboxing. Typically, the library will obtain these values
1807 // from the properties set by the VM. If the properties are for
1808 // internal implementation use only, these properties should be
1809 // masked from the system properties.
1810 //
1811 // Save a private copy of the system properties object that
1812 // can only be accessed by the internal implementation.
1813 VM.saveProperties(tempProps);
1814 props = createProperties(tempProps);
1815
1816 // Check if sun.jnu.encoding is supported. If not, replace it with UTF-8.
1817 var jnuEncoding = props.getProperty("sun.jnu.encoding");
1818 if (jnuEncoding == null || !Charset.isSupported(jnuEncoding)) {
1819 notSupportedJnuEncoding = jnuEncoding == null ? "null" : jnuEncoding;
1820 props.setProperty("sun.jnu.encoding", "UTF-8");
1821 }
1822
1823 StaticProperty.javaHome(); // Load StaticProperty to cache the property values
1824
1825 lineSeparator = props.getProperty("line.separator");
1826
1827 FileInputStream fdIn = new In(FileDescriptor.in);
1828 FileOutputStream fdOut = new Out(FileDescriptor.out);
1829 FileOutputStream fdErr = new Out(FileDescriptor.err);
1830 initialIn = new BufferedInputStream(fdIn);
1831 setIn0(initialIn);
1832 // stdout/err.encoding are set when the VM is associated with the terminal,
1833 // thus they are equivalent to Console.charset(), otherwise the encodings
1834 // of those properties default to native.encoding
1835 setOut0(newPrintStream(fdOut, props.getProperty("stdout.encoding")));
1836 initialErr = newPrintStream(fdErr, props.getProperty("stderr.encoding"));
1837 setErr0(initialErr);
1838
1839 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1840 Terminator.setup();
1841
1842 // Initialize any miscellaneous operating system settings that need to be
1843 // set for the class libraries. Currently this is no-op everywhere except
1844 // for Windows where the process-wide error mode is set before the java.io
1845 // classes are used.
1846 VM.initializeOSEnvironment();
1847
1848 // start Finalizer and Reference Handler threads
1849 SharedSecrets.getJavaLangRefAccess().startThreads();
1850
1851 // system properties, java.lang and other core classes are now initialized
1852 VM.initLevel(1);
1853 }
1854
1855 /**
1856 * System.in.
1857 */
1858 private static class In extends FileInputStream {
1859 In(FileDescriptor fd) {
1860 super(fd);
1861 }
1862
1863 @Override
1864 public int read() throws IOException {
1865 boolean attempted = Blocker.begin();
1866 try {
1867 return super.read();
1868 } finally {
1869 Blocker.end(attempted);
1870 }
1871 }
1872
1873 @Override
1874 public int read(byte[] b) throws IOException {
1875 boolean attempted = Blocker.begin();
1876 try {
1877 return super.read(b);
1878 } finally {
1879 Blocker.end(attempted);
1880 }
1881 }
1882
1883 @Override
1884 public int read(byte[] b, int off, int len) throws IOException {
1885 boolean attempted = Blocker.begin();
1886 try {
1887 return super.read(b, off, len);
1888 } finally {
1889 Blocker.end(attempted);
1890 }
1891 }
1892 }
1893
1894 /**
1895 * System.out/System.err wrap this output stream.
1896 */
1897 private static class Out extends FileOutputStream {
1898 Out(FileDescriptor fd) {
1899 super(fd);
1900 }
1901
1902 @Override
1903 public void write(int b) throws IOException {
1904 boolean attempted = Blocker.begin();
1905 try {
1906 super.write(b);
1907 } finally {
1908 Blocker.end(attempted);
1909 }
1910 }
1911
1912 @Override
1913 public void write(byte[] b) throws IOException {
1914 boolean attempted = Blocker.begin();
1915 try {
1916 super.write(b);
1917 } finally {
1918 Blocker.end(attempted);
1919 }
1920 }
1921
1922 @Override
1923 public void write(byte[] b, int off, int len) throws IOException {
1924 boolean attempted = Blocker.begin();
1925 try {
1926 super.write(b, off, len);
1927 } finally {
1928 Blocker.end(attempted);
1929 }
1930 }
1931 }
1932
1933 // @see #initPhase2()
1934 static ModuleLayer bootLayer;
1935
1936 /*
1937 * Invoked by VM. Phase 2 module system initialization.
1938 * Only classes in java.base can be loaded in this phase.
1939 *
1940 * @param printToStderr print exceptions to stderr rather than stdout
1941 * @param printStackTrace print stack trace when exception occurs
1942 *
1943 * @return JNI_OK for success, JNI_ERR for failure
1944 */
1945 private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
1946
1947 try {
1948 bootLayer = ModuleBootstrap.boot();
1949 } catch (Exception | Error e) {
1950 logInitException(printToStderr, printStackTrace,
1951 "Error occurred during initialization of boot layer", e);
1952 return -1; // JNI_ERR
1953 }
1954
1955 // module system initialized
1956 VM.initLevel(2);
1957
1958 return 0; // JNI_OK
1959 }
1960
1961 /*
1962 * Invoked by VM. Phase 3 is the final system initialization:
1963 * 1. set system class loader
1964 * 2. set TCCL
1965 *
1966 * This method must be called after the module system initialization.
1967 */
1968 private static void initPhase3() {
1969
1970 // Emit a warning if java.io.tmpdir is set via the command line
1971 // to a directory that doesn't exist
1972 if (SystemProps.isBadIoTmpdir()) {
1973 System.err.println("WARNING: java.io.tmpdir directory does not exist");
1974 }
1975
1976 String smProp = System.getProperty("java.security.manager");
1977 if (smProp != null) {
1978 switch (smProp) {
1979 case "disallow":
1980 break;
1981 case "allow":
1982 case "":
1983 case "default":
1984 default:
1985 throw new Error("A command line option has attempted to allow or enable the Security Manager."
1986 + " Enabling a Security Manager is not supported.");
1987 }
1988 }
1989
1990 // Emit a warning if `sun.jnu.encoding` is not supported.
1991 if (notSupportedJnuEncoding != null) {
1992 System.err.println(
1993 "WARNING: The encoding of the underlying platform's" +
1994 " file system is not supported: " +
1995 notSupportedJnuEncoding);
1996 }
1997
1998 // initializing the system class loader
1999 VM.initLevel(3);
2000
2001 // system class loader initialized
2002 ClassLoader scl = ClassLoader.initSystemClassLoader();
2003
2004 // set TCCL
2005 Thread.currentThread().setContextClassLoader(scl);
2006
2007 // system is fully initialized
2008 VM.initLevel(4);
2009 }
2010
2011 private static void setJavaLangAccess() {
2012 // Allow privileged classes outside of java.lang
2013 SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
2014 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
2015 return klass.getDeclaredPublicMethods(name, parameterTypes);
2016 }
2017 public Method findMethod(Class<?> klass, boolean publicOnly, String name, Class<?>... parameterTypes) {
2018 return klass.findMethod(publicOnly, name, parameterTypes);
2019 }
2020 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
2021 return klass.getConstantPool();
2022 }
2023 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
2024 return klass.casAnnotationType(oldType, newType);
2025 }
2026 public AnnotationType getAnnotationType(Class<?> klass) {
2027 return klass.getAnnotationType();
2028 }
2029 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2030 return klass.getDeclaredAnnotationMap();
2031 }
2032 public byte[] getRawClassAnnotations(Class<?> klass) {
2033 return klass.getRawAnnotations();
2034 }
2035 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2036 return klass.getRawTypeAnnotations();
2037 }
2038 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2039 return Class.getExecutableTypeAnnotationBytes(executable);
2040 }
2041 public <E extends Enum<E>>
2042 E[] getEnumConstantsShared(Class<E> klass) {
2043 return klass.getEnumConstantsShared();
2044 }
2045 public int classFileVersion(Class<?> clazz) {
2046 return clazz.getClassFileVersion();
2047 }
2048 public void blockedOn(Interruptible b) {
2049 Thread.currentThread().blockedOn(b);
2050 }
2051 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2052 Shutdown.add(slot, registerShutdownInProgress, hook);
2053 }
2054 @SuppressWarnings("removal")
2055 public void invokeFinalize(Object o) throws Throwable {
2056 o.finalize();
2057 }
2058 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2059 return cl.createOrGetClassLoaderValueMap();
2060 }
2061 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2062 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2063 }
2064 public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd,
2065 boolean initialize, int flags, Object classData) {
2066 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData);
2067 }
2068 public Class<?> findBootstrapClassOrNull(String name) {
2069 return ClassLoader.findBootstrapClassOrNull(name);
2070 }
2071 public Package definePackage(ClassLoader cl, String name, Module module) {
2072 return cl.definePackage(name, module);
2073 }
2074 public Module defineModule(ClassLoader loader,
2075 ModuleDescriptor descriptor,
2076 URI uri) {
2077 return new Module(null, loader, descriptor, uri);
2078 }
2079 public Module defineUnnamedModule(ClassLoader loader) {
2080 return new Module(loader);
2081 }
2082 public void addReads(Module m1, Module m2) {
2083 m1.implAddReads(m2);
2084 }
2085 public void addReadsAllUnnamed(Module m) {
2086 m.implAddReadsAllUnnamed();
2087 }
2088 public void addExports(Module m, String pn) {
2089 m.implAddExports(pn);
2090 }
2091 public void addExports(Module m, String pn, Module other) {
2092 m.implAddExports(pn, other);
2093 }
2094 public void addExportsToAllUnnamed(Module m, String pn) {
2095 m.implAddExportsToAllUnnamed(pn);
2096 }
2097 public void addOpens(Module m, String pn, Module other) {
2098 m.implAddOpens(pn, other);
2099 }
2100 public void addOpensToAllUnnamed(Module m, String pn) {
2101 m.implAddOpensToAllUnnamed(pn);
2102 }
2103 public void addUses(Module m, Class<?> service) {
2104 m.implAddUses(service);
2105 }
2106 public boolean isReflectivelyExported(Module m, String pn, Module other) {
2107 return m.isReflectivelyExported(pn, other);
2108 }
2109 public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2110 return m.isReflectivelyOpened(pn, other);
2111 }
2112 public Module addEnableNativeAccess(Module m) {
2113 return m.implAddEnableNativeAccess();
2114 }
2115 public boolean addEnableNativeAccess(ModuleLayer layer, String name) {
2116 return layer.addEnableNativeAccess(name);
2117 }
2118 public void addEnableNativeAccessToAllUnnamed() {
2119 Module.implAddEnableNativeAccessToAllUnnamed();
2120 }
2121 public void ensureNativeAccess(Module m, Class<?> owner, String methodName, Class<?> currentClass, boolean jni) {
2122 m.ensureNativeAccess(owner, methodName, currentClass, jni);
2123 }
2124 public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2125 return layer.getServicesCatalog();
2126 }
2127 public void bindToLoader(ModuleLayer layer, ClassLoader loader) {
2128 layer.bindToLoader(loader);
2129 }
2130 public Stream<ModuleLayer> layers(ModuleLayer layer) {
2131 return layer.layers();
2132 }
2133 public Stream<ModuleLayer> layers(ClassLoader loader) {
2134 return ModuleLayer.layers(loader);
2135 }
2136
2137 public int countPositives(byte[] bytes, int offset, int length) {
2138 return StringCoding.countPositives(bytes, offset, length);
2139 }
2140 public int countNonZeroAscii(String s) {
2141 return StringCoding.countNonZeroAscii(s);
2142 }
2143 public String uncheckedNewStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
2144 return String.newStringNoRepl(bytes, cs);
2145 }
2146 public char uncheckedGetUTF16Char(byte[] bytes, int index) {
2147 return StringUTF16.getChar(bytes, index);
2148 }
2149 public void uncheckedPutCharUTF16(byte[] bytes, int index, int ch) {
2150 StringUTF16.putChar(bytes, index, ch);
2151 }
2152 public byte[] uncheckedGetBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2153 return String.getBytesNoRepl(s, cs);
2154 }
2155
2156 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2157 return String.newStringUTF8NoRepl(bytes, off, len, true);
2158 }
2159
2160 public byte[] getBytesUTF8NoRepl(String s) {
2161 return String.getBytesUTF8NoRepl(s);
2162 }
2163
2164 public void inflateBytesToChars(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2165 StringLatin1.inflate(src, srcOff, dst, dstOff, len);
2166 }
2167
2168 public int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2169 return String.decodeASCII(src, srcOff, dst, dstOff, len);
2170 }
2171
2172 public int uncheckedEncodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len) {
2173 return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
2174 }
2175
2176 public InputStream initialSystemIn() {
2177 return initialIn;
2178 }
2179
2180 public PrintStream initialSystemErr() {
2181 return initialErr;
2182 }
2183
2184 public void setCause(Throwable t, Throwable cause) {
2185 t.setCause(cause);
2186 }
2187
2188 public ProtectionDomain protectionDomain(Class<?> c) {
2189 return c.getProtectionDomain();
2190 }
2191
2192 public MethodHandle stringConcatHelper(String name, MethodType methodType) {
2193 return StringConcatHelper.lookupStatic(name, methodType);
2194 }
2195
2196 public long stringConcatInitialCoder() {
2197 return StringConcatHelper.initialCoder();
2198 }
2199
2200 public long stringConcatMix(long lengthCoder, String constant) {
2201 return StringConcatHelper.mix(lengthCoder, constant);
2202 }
2203
2204 public long stringConcatMix(long lengthCoder, char value) {
2205 return StringConcatHelper.mix(lengthCoder, value);
2206 }
2207
2208 public Object uncheckedStringConcat1(String[] constants) {
2209 return new StringConcatHelper.Concat1(constants);
2210 }
2211
2212 public byte stringInitCoder() {
2213 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
2214 }
2215
2216 public byte stringCoder(String str) {
2217 return str.coder();
2218 }
2219
2220 public String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
2221 return String.join(prefix, suffix, delimiter, elements, size);
2222 }
2223
2224 public String concat(String prefix, Object value, String suffix) {
2225 return StringConcatHelper.concat(prefix, value, suffix);
2226 }
2227
2228 public Object classData(Class<?> c) {
2229 return c.getClassData();
2230 }
2231
2232 @Override
2233 public NativeLibraries nativeLibrariesFor(ClassLoader loader) {
2234 return ClassLoader.nativeLibrariesFor(loader);
2235 }
2236
2237 public Thread[] getAllThreads() {
2238 return Thread.getAllThreads();
2239 }
2240
2241 public ThreadContainer threadContainer(Thread thread) {
2242 return thread.threadContainer();
2243 }
2244
2245 public void start(Thread thread, ThreadContainer container) {
2246 thread.start(container);
2247 }
2248
2249 public StackableScope headStackableScope(Thread thread) {
2250 return thread.headStackableScopes();
2251 }
2252
2253 public void setHeadStackableScope(StackableScope scope) {
2254 Thread.setHeadStackableScope(scope);
2255 }
2256
2257 public Thread currentCarrierThread() {
2258 return Thread.currentCarrierThread();
2259 }
2260
2261 public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
2262 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
2263 }
2264
2265 public <T> void setCarrierThreadLocal(CarrierThreadLocal<T> local, T value) {
2266 ((ThreadLocal<T>)local).setCarrierThreadLocal(value);
2267 }
2268
2269 public void removeCarrierThreadLocal(CarrierThreadLocal<?> local) {
2270 ((ThreadLocal<?>)local).removeCarrierThreadLocal();
2271 }
2272
2273 public Object[] scopedValueCache() {
2274 return Thread.scopedValueCache();
2275 }
2276
2277 public void setScopedValueCache(Object[] cache) {
2278 Thread.setScopedValueCache(cache);
2279 }
2280
2281 public Object scopedValueBindings() {
2282 return Thread.scopedValueBindings();
2283 }
2284
2285 public Continuation getContinuation(Thread thread) {
2286 return thread.getContinuation();
2287 }
2288
2289 public void setContinuation(Thread thread, Continuation continuation) {
2290 thread.setContinuation(continuation);
2291 }
2292
2293 public ContinuationScope virtualThreadContinuationScope() {
2294 return VirtualThread.continuationScope();
2295 }
2296
2297 public void parkVirtualThread() {
2298 Thread thread = Thread.currentThread();
2299 if (thread instanceof BaseVirtualThread vthread) {
2300 vthread.park();
2301 } else {
2302 throw new WrongThreadException();
2303 }
2304 }
2305
2306 public void parkVirtualThread(long nanos) {
2307 Thread thread = Thread.currentThread();
2308 if (thread instanceof BaseVirtualThread vthread) {
2309 vthread.parkNanos(nanos);
2310 } else {
2311 throw new WrongThreadException();
2312 }
2313 }
2314
2315 public void unparkVirtualThread(Thread thread) {
2316 if (thread instanceof BaseVirtualThread vthread) {
2317 vthread.unpark();
2318 } else {
2319 throw new WrongThreadException();
2320 }
2321 }
2322
2323 public Executor virtualThreadDefaultScheduler() {
2324 return VirtualThread.defaultScheduler();
2325 }
2326
2327 public StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
2328 ContinuationScope contScope,
2329 Continuation continuation) {
2330 return StackWalker.newInstance(options, null, contScope, continuation);
2331 }
2332
2333 public int classFileFormatVersion(Class<?> clazz) {
2334 return clazz.getClassFileVersion();
2335 }
2336
2337 public String getLoaderNameID(ClassLoader loader) {
2338 return loader != null ? loader.nameAndId() : "null";
2339 }
2340
2341 @Override
2342 public void copyToSegmentRaw(String string, MemorySegment segment, long offset) {
2343 string.copyToSegmentRaw(segment, offset);
2344 }
2345
2346 @Override
2347 public boolean bytesCompatible(String string, Charset charset) {
2348 return string.bytesCompatible(charset);
2349 }
2350 });
2351 }
2352 }