1 /*
2 * Copyright (c) 1994, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package java.lang;
26
27 import java.io.BufferedInputStream;
28 import java.io.BufferedOutputStream;
29 import java.io.Console;
30 import java.io.FileDescriptor;
31 import java.io.FileInputStream;
32 import java.io.FileOutputStream;
33 import java.io.IOException;
34 import java.io.InputStream;
35 import java.io.OutputStream;
36 import java.io.PrintStream;
37 import java.lang.annotation.Annotation;
38 import java.lang.foreign.MemorySegment;
39 import java.lang.invoke.MethodHandle;
40 import java.lang.invoke.MethodType;
41 import java.lang.module.ModuleDescriptor;
42 import java.lang.reflect.Executable;
43 import java.lang.reflect.Method;
44 import java.net.URI;
45 import java.net.URL;
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.AccessController;
51 import java.security.CodeSource;
52 import java.security.PrivilegedAction;
53 import java.security.ProtectionDomain;
54 import java.util.Collections;
55 import java.util.List;
56 import java.util.Locale;
57 import java.util.Map;
58 import java.util.Objects;
59 import java.util.Properties;
60 import java.util.PropertyPermission;
61 import java.util.ResourceBundle;
62 import java.util.Set;
63 import java.util.WeakHashMap;
64 import java.util.concurrent.Executor;
65 import java.util.function.Supplier;
66 import java.util.concurrent.ConcurrentHashMap;
67 import java.util.stream.Stream;
68
69 import jdk.internal.javac.Restricted;
70 import jdk.internal.loader.NativeLibraries;
71 import jdk.internal.logger.LoggerFinderLoader.TemporaryLoggerFinder;
72 import jdk.internal.misc.Blocker;
73 import jdk.internal.misc.CarrierThreadLocal;
74 import jdk.internal.util.StaticProperty;
75 import jdk.internal.module.ModuleBootstrap;
76 import jdk.internal.module.ServicesCatalog;
77 import jdk.internal.reflect.CallerSensitive;
78 import jdk.internal.reflect.Reflection;
79 import jdk.internal.access.JavaLangAccess;
80 import jdk.internal.access.SharedSecrets;
81 import jdk.internal.logger.LoggerFinderLoader;
82 import jdk.internal.logger.LazyLoggers;
83 import jdk.internal.logger.LocalizedLoggerWrapper;
84 import jdk.internal.misc.VM;
85 import jdk.internal.util.SystemProps;
86 import jdk.internal.vm.Continuation;
87 import jdk.internal.vm.ContinuationScope;
88 import jdk.internal.vm.StackableScope;
89 import jdk.internal.vm.ThreadContainer;
90 import jdk.internal.vm.annotation.IntrinsicCandidate;
91 import jdk.internal.vm.annotation.Stable;
92 import sun.reflect.annotation.AnnotationType;
93 import sun.nio.ch.Interruptible;
94 import sun.nio.cs.UTF_8;
95 import sun.security.util.SecurityConstants;
96
97 /**
98 * The {@code System} class contains several useful class fields
99 * and methods. It cannot be instantiated.
100 *
101 * Among the facilities provided by the {@code System} class
102 * are standard input, standard output, and error output streams;
103 * access to externally defined properties and environment
104 * variables; a means of loading files and libraries; and a utility
105 * method for quickly copying a portion of an array.
106 *
107 * @since 1.0
108 */
109 public final class System {
110 /* Register the natives via the static initializer.
111 *
112 * The VM will invoke the initPhase1 method to complete the initialization
113 * of this class separate from <clinit>.
114 */
115 private static native void registerNatives();
116 static {
117 registerNatives();
118 }
119
120 /** Don't let anyone instantiate this class */
121 private System() {
122 }
123
124 /**
125 * The "standard" input stream. This stream is already
126 * open and ready to supply input data. Typically this stream
127 * corresponds to keyboard input or another input source specified by
128 * the host environment or user. In case this stream is wrapped
129 * in a {@link java.io.InputStreamReader}, {@link Console#charset()}
130 * should be used for the charset, or consider using
131 * {@link Console#reader()}.
132 *
133 * @see Console#charset()
134 * @see Console#reader()
135 */
136 public static final InputStream in = null;
137
138 /**
139 * The "standard" output stream. This stream is already
140 * open and ready to accept output data. Typically this stream
141 * corresponds to display output or another output destination
142 * specified by the host environment or user. The encoding used
143 * in the conversion from characters to bytes is equivalent to
144 * {@link ##stdout.encoding stdout.encoding}.
145 * <p>
146 * For simple stand-alone Java applications, a typical way to write
147 * a line of output data is:
148 * <blockquote><pre>
149 * System.out.println(data)
150 * </pre></blockquote>
151 * <p>
152 * See the {@code println} methods in class {@code PrintStream}.
153 *
154 * @see java.io.PrintStream#println()
155 * @see java.io.PrintStream#println(boolean)
156 * @see java.io.PrintStream#println(char)
157 * @see java.io.PrintStream#println(char[])
158 * @see java.io.PrintStream#println(double)
159 * @see java.io.PrintStream#println(float)
160 * @see java.io.PrintStream#println(int)
161 * @see java.io.PrintStream#println(long)
162 * @see java.io.PrintStream#println(java.lang.Object)
163 * @see java.io.PrintStream#println(java.lang.String)
164 * @see ##stdout.encoding stdout.encoding
165 */
166 public static final PrintStream out = null;
167
168 /**
169 * The "standard" error output stream. This stream is already
170 * open and ready to accept output data.
171 * <p>
172 * Typically this stream corresponds to display output or another
173 * output destination specified by the host environment or user. By
174 * convention, this output stream is used to display error messages
175 * or other information that should come to the immediate attention
176 * of a user even if the principal output stream, the value of the
177 * variable {@code out}, has been redirected to a file or other
178 * destination that is typically not continuously monitored.
179 * The encoding used in the conversion from characters to bytes is
180 * equivalent to {@link ##stderr.encoding stderr.encoding}.
181 *
182 * @see ##stderr.encoding stderr.encoding
183 */
184 public static final PrintStream err = null;
185
186 // Initial values of System.in and System.err, set in initPhase1().
187 private static @Stable InputStream initialIn;
188 private static @Stable PrintStream initialErr;
189
190 // `sun.jnu.encoding` if it is not supported. Otherwise null.
191 // It is initialized in `initPhase1()` before any charset providers
192 // are initialized.
193 private static String notSupportedJnuEncoding;
194
195 /**
196 * Reassigns the "standard" input stream.
197 *
198 * @param in the new standard input stream.
199 *
200 * @since 1.1
201 */
202 public static void setIn(InputStream in) {
203 checkIO();
204 setIn0(in);
205 }
206
207 /**
208 * Reassigns the "standard" output stream.
209 *
210 * @param out the new standard output stream
211 *
212 * @since 1.1
213 */
214 public static void setOut(PrintStream out) {
215 checkIO();
216 setOut0(out);
217 }
218
219 /**
220 * Reassigns the "standard" error output stream.
221 *
222 * @param err the new standard error output stream.
223 *
224 * @since 1.1
225 */
226 public static void setErr(PrintStream err) {
227 checkIO();
228 setErr0(err);
229 }
230
231 private static volatile Console cons;
232
233 /**
234 * Returns the unique {@link java.io.Console Console} object associated
235 * with the current Java virtual machine, if any.
236 *
237 * @return The system console, if any, otherwise {@code null}.
238 *
239 * @since 1.6
240 */
241 public static Console console() {
242 Console c;
243 if ((c = cons) == null) {
244 synchronized (System.class) {
245 if ((c = cons) == null) {
246 cons = c = SharedSecrets.getJavaIOAccess().console();
247 }
248 }
249 }
250 return c;
251 }
252
253 /**
254 * Returns the channel inherited from the entity that created this
255 * Java virtual machine.
256 *
257 * This method returns the channel obtained by invoking the
258 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
259 * inheritedChannel} method of the system-wide default
260 * {@link java.nio.channels.spi.SelectorProvider} object.
261 *
262 * <p> In addition to the network-oriented channels described in
263 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
264 * inheritedChannel}, this method may return other kinds of
265 * channels in the future.
266 *
267 * @return The inherited channel, if any, otherwise {@code null}.
268 *
269 * @throws IOException
270 * If an I/O error occurs
271 *
272 * @since 1.5
273 */
274 public static Channel inheritedChannel() throws IOException {
275 return SelectorProvider.provider().inheritedChannel();
276 }
277
278 private static void checkIO() {
279 @SuppressWarnings("removal")
280 SecurityManager sm = getSecurityManager();
281 if (sm != null) {
282 sm.checkPermission(new RuntimePermission("setIO"));
283 }
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 private static class CallersHolder {
291 // Remember callers of setSecurityManager() here so that warning
292 // is only printed once for each different caller
293 static final Map<Class<?>, Boolean> callers
294 = Collections.synchronizedMap(new WeakHashMap<>());
295 }
296
297 static URL codeSource(Class<?> clazz) {
298 PrivilegedAction<ProtectionDomain> pa = clazz::getProtectionDomain;
299 @SuppressWarnings("removal")
300 CodeSource cs = AccessController.doPrivileged(pa).getCodeSource();
301 return (cs != null) ? cs.getLocation() : null;
302 }
303
304 /**
305 * Throws {@code UnsupportedOperationException}. Setting a security manager
306 * is not supported.
307 *
308 * @param sm ignored
309 * @throws UnsupportedOperationException always
310 * @see #getSecurityManager
311 * @deprecated This method originally set
312 * {@linkplain SecurityManager the system-wide Security Manager}.
313 * Setting a Security Manager is no longer supported. There is no
314 * replacement for the Security Manager or this method.
315 */
316 @Deprecated(since="17", forRemoval=true)
317 public static void setSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
318 throw new UnsupportedOperationException(
319 "Setting a Security Manager is not supported");
320 }
321
322 /**
323 * Returns {@code null}. Setting a security manager is not supported.
324 *
325 * @return {@code null}
326 * @see #setSecurityManager
327 * @deprecated This method originally returned
328 * {@linkplain SecurityManager the system-wide Security Manager}.
329 * Setting a Security Manager is no longer supported. There is no
330 * replacement for the Security Manager or this method.
331 */
332 @SuppressWarnings("removal")
333 @Deprecated(since="17", forRemoval=true)
334 public static SecurityManager getSecurityManager() {
335 return null;
336 }
337
338 /**
339 * Returns the current time in milliseconds. Note that
340 * while the unit of time of the return value is a millisecond,
341 * the granularity of the value depends on the underlying
342 * operating system and may be larger. For example, many
343 * operating systems measure time in units of tens of
344 * milliseconds.
345 *
346 * <p> See the description of the class {@code Date} for
347 * a discussion of slight discrepancies that may arise between
348 * "computer time" and coordinated universal time (UTC).
349 *
350 * @return the difference, measured in milliseconds, between
351 * the current time and midnight, January 1, 1970 UTC.
352 * @see java.util.Date
353 */
354 @IntrinsicCandidate
355 public static native long currentTimeMillis();
356
357 /**
358 * Returns the current value of the running Java Virtual Machine's
359 * high-resolution time source, in nanoseconds.
360 *
361 * This method can only be used to measure elapsed time and is
362 * not related to any other notion of system or wall-clock time.
363 * The value returned represents nanoseconds since some fixed but
364 * arbitrary <i>origin</i> time (perhaps in the future, so values
365 * may be negative). The same origin is used by all invocations of
366 * this method in an instance of a Java virtual machine; other
367 * virtual machine instances are likely to use a different origin.
368 *
369 * <p>This method provides nanosecond precision, but not necessarily
370 * nanosecond resolution (that is, how frequently the value changes)
371 * - no guarantees are made except that the resolution is at least as
372 * good as that of {@link #currentTimeMillis()}.
373 *
374 * <p>Differences in successive calls that span greater than
375 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
376 * correctly compute elapsed time due to numerical overflow.
377 *
378 * <p>The values returned by this method become meaningful only when
379 * the difference between two such values, obtained within the same
380 * instance of a Java virtual machine, is computed.
381 *
382 * <p>For example, to measure how long some code takes to execute:
383 * <pre> {@code
384 * long startTime = System.nanoTime();
385 * // ... the code being measured ...
386 * long elapsedNanos = System.nanoTime() - startTime;}</pre>
387 *
388 * <p>To compare elapsed time against a timeout, use <pre> {@code
389 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
390 * instead of <pre> {@code
391 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
392 * because of the possibility of numerical overflow.
393 *
394 * @return the current value of the running Java Virtual Machine's
395 * high-resolution time source, in nanoseconds
396 * @since 1.5
397 */
398 @IntrinsicCandidate
399 public static native long nanoTime();
400
401 /**
402 * Copies an array from the specified source array, beginning at the
403 * specified position, to the specified position of the destination array.
404 * A subsequence of array components are copied from the source
405 * array referenced by {@code src} to the destination array
406 * referenced by {@code dest}. The number of components copied is
407 * equal to the {@code length} argument. The components at
408 * positions {@code srcPos} through
409 * {@code srcPos+length-1} in the source array are copied into
410 * positions {@code destPos} through
411 * {@code destPos+length-1}, respectively, of the destination
412 * array.
413 * <p>
414 * If the {@code src} and {@code dest} arguments refer to the
415 * same array object, then the copying is performed as if the
416 * components at positions {@code srcPos} through
417 * {@code srcPos+length-1} were first copied to a temporary
418 * array with {@code length} components and then the contents of
419 * the temporary array were copied into positions
420 * {@code destPos} through {@code destPos+length-1} of the
421 * destination array.
422 * <p>
423 * If {@code dest} is {@code null}, then a
424 * {@code NullPointerException} is thrown.
425 * <p>
426 * If {@code src} is {@code null}, then a
427 * {@code NullPointerException} is thrown and the destination
428 * array is not modified.
429 * <p>
430 * Otherwise, if any of the following is true, an
431 * {@code ArrayStoreException} is thrown and the destination is
432 * not modified:
433 * <ul>
434 * <li>The {@code src} argument refers to an object that is not an
435 * array.
436 * <li>The {@code dest} argument refers to an object that is not an
437 * array.
438 * <li>The {@code src} argument and {@code dest} argument refer
439 * to arrays whose component types are different primitive types.
440 * <li>The {@code src} argument refers to an array with a primitive
441 * component type and the {@code dest} argument refers to an array
442 * with a reference component type.
443 * <li>The {@code src} argument refers to an array with a reference
444 * component type and the {@code dest} argument refers to an array
445 * with a primitive component type.
446 * </ul>
447 * <p>
448 * Otherwise, if any of the following is true, an
449 * {@code IndexOutOfBoundsException} is
450 * thrown and the destination is not modified:
451 * <ul>
452 * <li>The {@code srcPos} argument is negative.
453 * <li>The {@code destPos} argument is negative.
454 * <li>The {@code length} argument is negative.
455 * <li>{@code srcPos+length} is greater than
456 * {@code src.length}, the length of the source array.
457 * <li>{@code destPos+length} is greater than
458 * {@code dest.length}, the length of the destination array.
459 * </ul>
460 * <p>
461 * Otherwise, if any actual component of the source array from
462 * position {@code srcPos} through
463 * {@code srcPos+length-1} cannot be converted to the component
464 * type of the destination array by assignment conversion, an
465 * {@code ArrayStoreException} is thrown. In this case, let
466 * <b><i>k</i></b> be the smallest nonnegative integer less than
467 * length such that {@code src[srcPos+}<i>k</i>{@code ]}
468 * cannot be converted to the component type of the destination
469 * array; when the exception is thrown, source array components from
470 * positions {@code srcPos} through
471 * {@code srcPos+}<i>k</i>{@code -1}
472 * will already have been copied to destination array positions
473 * {@code destPos} through
474 * {@code destPos+}<i>k</I>{@code -1} and no other
475 * positions of the destination array will have been modified.
476 * (Because of the restrictions already itemized, this
477 * paragraph effectively applies only to the situation where both
478 * arrays have component types that are reference types.)
479 *
480 * @param src the source array.
481 * @param srcPos starting position in the source array.
482 * @param dest the destination array.
483 * @param destPos starting position in the destination data.
484 * @param length the number of array elements to be copied.
485 * @throws IndexOutOfBoundsException if copying would cause
486 * access of data outside array bounds.
487 * @throws ArrayStoreException if an element in the {@code src}
488 * array could not be stored into the {@code dest} array
489 * because of a type mismatch.
490 * @throws NullPointerException if either {@code src} or
491 * {@code dest} is {@code null}.
492 */
493 @IntrinsicCandidate
494 public static native void arraycopy(Object src, int srcPos,
495 Object dest, int destPos,
496 int length);
497
498 /**
499 * Returns the same hash code for the given object as
500 * would be returned by the default method hashCode(),
501 * whether or not the given object's class overrides
502 * hashCode().
503 * The hash code for the null reference is zero.
504 *
505 * @param x object for which the hashCode is to be calculated
506 * @return the hashCode
507 * @since 1.1
508 * @see Object#hashCode
509 * @see java.util.Objects#hashCode(Object)
510 */
511 @IntrinsicCandidate
512 public static native int identityHashCode(Object x);
513
514 /**
515 * System properties.
516 *
517 * See {@linkplain #getProperties getProperties} for details.
518 */
519 private static Properties props;
520
521 /**
522 * Determines the current system properties.
523 * <p>
524 * The current set of system properties for use by the
525 * {@link #getProperty(String)} method is returned as a
526 * {@code Properties} object. If there is no current set of
527 * system properties, a set of system properties is first created and
528 * initialized. This set of system properties includes a value
529 * for each of the following keys unless the description of the associated
530 * value indicates that the value is optional.
531 * <table class="striped" style="text-align:left">
532 * <caption style="display:none">Shows property keys and associated values</caption>
533 * <thead>
534 * <tr><th scope="col">Key</th>
535 * <th scope="col">Description of Associated Value</th></tr>
536 * </thead>
537 * <tbody>
538 * <tr><th scope="row">{@systemProperty java.version}</th>
539 * <td>Java Runtime Environment version, which may be interpreted
540 * as a {@link Runtime.Version}</td></tr>
541 * <tr><th scope="row">{@systemProperty java.version.date}</th>
542 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
543 * format, which may be interpreted as a {@link
544 * java.time.LocalDate}</td></tr>
545 * <tr><th scope="row">{@systemProperty java.vendor}</th>
546 * <td>Java Runtime Environment vendor</td></tr>
547 * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
548 * <td>Java vendor URL</td></tr>
549 * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
550 * <td>Java vendor version <em>(optional)</em> </td></tr>
551 * <tr><th scope="row">{@systemProperty java.home}</th>
552 * <td>Java installation directory</td></tr>
553 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
554 * <td>Java Virtual Machine specification version, whose value is the
555 * {@linkplain Runtime.Version#feature feature} element of the
556 * {@linkplain Runtime#version() runtime version}</td></tr>
557 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
558 * <td>Java Virtual Machine specification vendor</td></tr>
559 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
560 * <td>Java Virtual Machine specification name</td></tr>
561 * <tr><th scope="row">{@systemProperty java.vm.version}</th>
562 * <td>Java Virtual Machine implementation version which may be
563 * interpreted as a {@link Runtime.Version}</td></tr>
564 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
565 * <td>Java Virtual Machine implementation vendor</td></tr>
566 * <tr><th scope="row">{@systemProperty java.vm.name}</th>
567 * <td>Java Virtual Machine implementation name</td></tr>
568 * <tr><th scope="row">{@systemProperty java.specification.version}</th>
569 * <td>Java Runtime Environment specification version, whose value is
570 * the {@linkplain Runtime.Version#feature feature} element of the
571 * {@linkplain Runtime#version() runtime version}</td></tr>
572 * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
573 * <td>Java Runtime Environment specification maintenance version,
574 * may be interpreted as a positive integer <em>(optional, see below)</em></td></tr>
575 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
576 * <td>Java Runtime Environment specification vendor</td></tr>
577 * <tr><th scope="row">{@systemProperty java.specification.name}</th>
578 * <td>Java Runtime Environment specification name</td></tr>
579 * <tr><th scope="row">{@systemProperty java.class.version}</th>
580 * <td>{@linkplain java.lang.reflect.ClassFileFormatVersion#latest() Latest}
581 * Java class file format version recognized by the Java runtime as {@code "MAJOR.MINOR"}
582 * where {@link java.lang.reflect.ClassFileFormatVersion#major() MAJOR} and {@code MINOR}
583 * are both formatted as decimal integers</td></tr>
584 * <tr><th scope="row">{@systemProperty java.class.path}</th>
585 * <td>Java class path (refer to
586 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
587 * <tr><th scope="row">{@systemProperty java.library.path}</th>
588 * <td>List of paths to search when loading libraries</td></tr>
589 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
590 * <td>Default temp file path</td></tr>
591 * <tr><th scope="row">{@systemProperty os.name}</th>
592 * <td>Operating system name</td></tr>
593 * <tr><th scope="row">{@systemProperty os.arch}</th>
594 * <td>Operating system architecture</td></tr>
595 * <tr><th scope="row">{@systemProperty os.version}</th>
596 * <td>Operating system version</td></tr>
597 * <tr><th scope="row">{@systemProperty file.separator}</th>
598 * <td>File separator ("/" on UNIX)</td></tr>
599 * <tr><th scope="row">{@systemProperty path.separator}</th>
600 * <td>Path separator (":" on UNIX)</td></tr>
601 * <tr><th scope="row">{@systemProperty line.separator}</th>
602 * <td>Line separator ("\n" on UNIX)</td></tr>
603 * <tr><th scope="row">{@systemProperty user.name}</th>
604 * <td>User's account name</td></tr>
605 * <tr><th scope="row">{@systemProperty user.home}</th>
606 * <td>User's home directory</td></tr>
607 * <tr><th scope="row">{@systemProperty user.dir}</th>
608 * <td>User's current working directory</td></tr>
609 * <tr><th scope="row">{@systemProperty native.encoding}</th>
610 * <td>Character encoding name derived from the host environment and/or
611 * the user's settings. Setting this system property has no effect.</td></tr>
612 * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
613 * <td>Character encoding name for {@link System#out System.out} and
614 * {@link System#console() System.console()}.
615 * The Java runtime can be started with the system property set to {@code UTF-8},
616 * starting it with the property set to another value leads to undefined behavior.
617 * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
618 * <td>Character encoding name for {@link System#err System.err}.
619 * The Java runtime can be started with the system property set to {@code UTF-8},
620 * starting it with the property set to another value leads to undefined behavior.
621 * </tbody>
622 * </table>
623 * <p>
624 * The {@code java.specification.maintenance.version} property is
625 * defined if the specification implemented by this runtime at the
626 * time of its construction had undergone a <a
627 * href="https://jcp.org/en/procedures/jcp2#3.6.4">maintenance
628 * release</a>. When defined, its value identifies that
629 * maintenance release. To indicate the first maintenance release
630 * this property will have the value {@code "1"}, to indicate the
631 * second maintenance release this property will have the value
632 * {@code "2"}, and so on.
633 * <p>
634 * Multiple paths in a system property value are separated by the path
635 * separator character of the platform.
636 * <p>
637 * Additional locale-related system properties defined by the
638 * {@link Locale##default_locale Default Locale} section in the {@code Locale}
639 * class description may also be obtained with this method.
640 *
641 * @apiNote
642 * <strong>Changing a standard system property may have unpredictable results
643 * unless otherwise specified.</strong>
644 * Property values may be cached during initialization or on first use.
645 * Setting a standard property after initialization using {@link #getProperties()},
646 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
647 * {@link #clearProperty(String)} may not have the desired effect.
648 *
649 * @implNote
650 * In addition to the standard system properties, the system
651 * properties may include the following keys:
652 * <table class="striped">
653 * <caption style="display:none">Shows property keys and associated values</caption>
654 * <thead>
655 * <tr><th scope="col">Key</th>
656 * <th scope="col">Description of Associated Value</th></tr>
657 * </thead>
658 * <tbody>
659 * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
660 * <td>The application module path</td></tr>
661 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
662 * <td>The upgrade module path</td></tr>
663 * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
664 * <td>The module name of the initial/main module</td></tr>
665 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
666 * <td>The main class name of the initial module</td></tr>
667 * <tr><th scope="row">{@systemProperty file.encoding}</th>
668 * <td>The name of the default charset, defaults to {@code UTF-8}.
669 * The property may be set on the command line to the value
670 * {@code UTF-8} or {@code COMPAT}. If set on the command line to
671 * the value {@code COMPAT} then the value is replaced with the
672 * value of the {@code native.encoding} property during startup.
673 * Setting the property to a value other than {@code UTF-8} or
674 * {@code COMPAT} leads to unspecified behavior.
675 * </td></tr>
676 * </tbody>
677 * </table>
678 *
679 * @return the system properties
680 * @see #setProperties
681 * @see java.util.Properties
682 */
683 public static Properties getProperties() {
684 @SuppressWarnings("removal")
685 SecurityManager sm = getSecurityManager();
686 if (sm != null) {
687 sm.checkPropertiesAccess();
688 }
689
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 @SuppressWarnings("removal")
729 SecurityManager sm = getSecurityManager();
730 if (sm != null) {
731 sm.checkPropertiesAccess();
732 }
733
734 if (props == null) {
735 Map<String, String> tempProps = SystemProps.initProperties();
736 VersionProps.init(tempProps);
737 props = createProperties(tempProps);
738 }
739 System.props = props;
740 }
741
742 /**
743 * Gets the system property indicated by the specified key.
744 * <p>
745 * If there is no current set of system properties, a set of system
746 * properties is first created and initialized in the same manner as
747 * for the {@code getProperties} method.
748 *
749 * @apiNote
750 * <strong>Changing a standard system property may have unpredictable results
751 * unless otherwise specified</strong>.
752 * See {@linkplain #getProperties getProperties} for details.
753 *
754 * @param key the name of the system property.
755 * @return the string value of the system property,
756 * or {@code null} if there is no property with that key.
757 *
758 * @throws NullPointerException if {@code key} is {@code null}.
759 * @throws IllegalArgumentException if {@code key} is empty.
760 * @see #setProperty
761 * @see java.lang.System#getProperties()
762 */
763 public static String getProperty(String key) {
764 checkKey(key);
765 @SuppressWarnings("removal")
766 SecurityManager sm = getSecurityManager();
767 if (sm != null) {
768 sm.checkPropertyAccess(key);
769 }
770
771 return props.getProperty(key);
772 }
773
774 /**
775 * Gets the system property indicated by the specified key.
776 * <p>
777 * If there is no current set of system properties, a set of system
778 * properties is first created and initialized in the same manner as
779 * for the {@code getProperties} method.
780 *
781 * @param key the name of the system property.
782 * @param def a default value.
783 * @return the string value of the system property,
784 * or the default value if there is no property with that key.
785 *
786 * @throws NullPointerException if {@code key} is {@code null}.
787 * @throws IllegalArgumentException if {@code key} is empty.
788 * @see #setProperty
789 * @see java.lang.System#getProperties()
790 */
791 public static String getProperty(String key, String def) {
792 checkKey(key);
793 @SuppressWarnings("removal")
794 SecurityManager sm = getSecurityManager();
795 if (sm != null) {
796 sm.checkPropertyAccess(key);
797 }
798
799 return props.getProperty(key, def);
800 }
801
802 /**
803 * Sets the system property indicated by the specified key.
804 *
805 * @apiNote
806 * <strong>Changing a standard system property may have unpredictable results
807 * unless otherwise specified</strong>.
808 * See {@linkplain #getProperties getProperties} for details.
809 *
810 * @param key the name of the system property.
811 * @param value the value of the system property.
812 * @return the previous value of the system property,
813 * or {@code null} if it did not have one.
814 *
815 * @throws NullPointerException if {@code key} or
816 * {@code value} is {@code null}.
817 * @throws IllegalArgumentException if {@code key} is empty.
818 * @see #getProperty
819 * @see java.lang.System#getProperty(java.lang.String)
820 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
821 * @since 1.2
822 */
823 public static String setProperty(String key, String value) {
824 checkKey(key);
825 @SuppressWarnings("removal")
826 SecurityManager sm = getSecurityManager();
827 if (sm != null) {
828 sm.checkPermission(new PropertyPermission(key,
829 SecurityConstants.PROPERTY_WRITE_ACTION));
830 }
831
832 return (String) props.setProperty(key, value);
833 }
834
835 /**
836 * Removes the system property indicated by the specified key.
837 *
838 * @apiNote
839 * <strong>Changing a standard system property may have unpredictable results
840 * unless otherwise specified</strong>.
841 * See {@linkplain #getProperties getProperties} method for details.
842 *
843 * @param key the name of the system property to be removed.
844 * @return the previous string value of the system property,
845 * or {@code null} if there was no property with that key.
846 *
847 * @throws NullPointerException if {@code key} is {@code null}.
848 * @throws IllegalArgumentException if {@code key} is empty.
849 * @see #getProperty
850 * @see #setProperty
851 * @see java.util.Properties
852 * @since 1.5
853 */
854 public static String clearProperty(String key) {
855 checkKey(key);
856 @SuppressWarnings("removal")
857 SecurityManager sm = getSecurityManager();
858 if (sm != null) {
859 sm.checkPermission(new PropertyPermission(key, "write"));
860 }
861
862 return (String) props.remove(key);
863 }
864
865 private static void checkKey(String key) {
866 if (key == null) {
867 throw new NullPointerException("key can't be null");
868 }
869 if (key.isEmpty()) {
870 throw new IllegalArgumentException("key can't be empty");
871 }
872 }
873
874 /**
875 * Gets the value of the specified environment variable. An
876 * environment variable is a system-dependent external named
877 * value.
878 *
879 * <p><a id="EnvironmentVSSystemProperties"><i>System
880 * properties</i> and <i>environment variables</i></a> are both
881 * conceptually mappings between names and values. Both
882 * mechanisms can be used to pass user-defined information to a
883 * Java process. Environment variables have a more global effect,
884 * because they are visible to all descendants of the process
885 * which defines them, not just the immediate Java subprocess.
886 * They can have subtly different semantics, such as case
887 * insensitivity, on different operating systems. For these
888 * reasons, environment variables are more likely to have
889 * unintended side effects. It is best to use system properties
890 * where possible. Environment variables should be used when a
891 * global effect is desired, or when an external system interface
892 * requires an environment variable (such as {@code PATH}).
893 *
894 * <p>On UNIX systems the alphabetic case of {@code name} is
895 * typically significant, while on Microsoft Windows systems it is
896 * typically not. For example, the expression
897 * {@code System.getenv("FOO").equals(System.getenv("foo"))}
898 * is likely to be true on Microsoft Windows.
899 *
900 * @param name the name of the environment variable
901 * @return the string value of the variable, or {@code null}
902 * if the variable is not defined in the system environment
903 * @throws NullPointerException if {@code name} is {@code null}
904 * @see #getenv()
905 * @see ProcessBuilder#environment()
906 */
907 public static String getenv(String name) {
908 @SuppressWarnings("removal")
909 SecurityManager sm = getSecurityManager();
910 if (sm != null) {
911 sm.checkPermission(new RuntimePermission("getenv."+name));
912 }
913
914 return ProcessEnvironment.getenv(name);
915 }
916
917
918 /**
919 * Returns an unmodifiable string map view of the current system environment.
920 * The environment is a system-dependent mapping from names to
921 * values which is passed from parent to child processes.
922 *
923 * <p>If the system does not support environment variables, an
924 * empty map is returned.
925 *
926 * <p>The returned map will never contain null keys or values.
927 * Attempting to query the presence of a null key or value will
928 * throw a {@link NullPointerException}. Attempting to query
929 * the presence of a key or value which is not of type
930 * {@link String} will throw a {@link ClassCastException}.
931 *
932 * <p>The returned map and its collection views may not obey the
933 * general contract of the {@link Object#equals} and
934 * {@link Object#hashCode} methods.
935 *
936 * <p>The returned map is typically case-sensitive on all platforms.
937 *
938 * <p>When passing information to a Java subprocess,
939 * <a href=#EnvironmentVSSystemProperties>system properties</a>
940 * are generally preferred over environment variables.
941 *
942 * @return the environment as a map of variable names to values
943 * @see #getenv(String)
944 * @see ProcessBuilder#environment()
945 * @since 1.5
946 */
947 public static java.util.Map<String,String> getenv() {
948 @SuppressWarnings("removal")
949 SecurityManager sm = getSecurityManager();
950 if (sm != null) {
951 sm.checkPermission(new RuntimePermission("getenv.*"));
952 }
953
954 return ProcessEnvironment.getenv();
955 }
956
957 /**
958 * {@code System.Logger} instances log messages that will be
959 * routed to the underlying logging framework the {@link System.LoggerFinder
960 * LoggerFinder} uses.
961 *
962 * {@code System.Logger} instances are typically obtained from
963 * the {@link java.lang.System System} class, by calling
964 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
965 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
966 * System.getLogger(loggerName, bundle)}.
967 *
968 * @see java.lang.System#getLogger(java.lang.String)
969 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
970 * @see java.lang.System.LoggerFinder
971 *
972 * @since 9
973 */
974 public interface Logger {
975
976 /**
977 * System {@linkplain Logger loggers} levels.
978 *
979 * A level has a {@linkplain #getName() name} and {@linkplain
980 * #getSeverity() severity}.
981 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
982 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
983 * by order of increasing severity.
984 * <br>
985 * {@link #ALL} and {@link #OFF}
986 * are simple markers with severities mapped respectively to
987 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
988 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
989 * <p>
990 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
991 * <p>
992 * {@linkplain System.Logger.Level System logger levels} are mapped to
993 * {@linkplain java.logging/java.util.logging.Level java.util.logging levels}
994 * of corresponding severity.
995 * <br>The mapping is as follows:
996 * <br><br>
997 * <table class="striped">
998 * <caption>System.Logger Severity Level Mapping</caption>
999 * <thead>
1000 * <tr><th scope="col">System.Logger Levels</th>
1001 * <th scope="col">java.util.logging Levels</th>
1002 * </thead>
1003 * <tbody>
1004 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
1005 * <td>{@link java.logging/java.util.logging.Level#ALL ALL}</td>
1006 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
1007 * <td>{@link java.logging/java.util.logging.Level#FINER FINER}</td>
1008 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
1009 * <td>{@link java.logging/java.util.logging.Level#FINE FINE}</td>
1010 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
1011 * <td>{@link java.logging/java.util.logging.Level#INFO INFO}</td>
1012 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
1013 * <td>{@link java.logging/java.util.logging.Level#WARNING WARNING}</td>
1014 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
1015 * <td>{@link java.logging/java.util.logging.Level#SEVERE SEVERE}</td>
1016 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
1017 * <td>{@link java.logging/java.util.logging.Level#OFF OFF}</td>
1018 * </tbody>
1019 * </table>
1020 *
1021 * @since 9
1022 *
1023 * @see java.lang.System.LoggerFinder
1024 * @see java.lang.System.Logger
1025 */
1026 @SuppressWarnings("doclint:reference") // cross-module links
1027 public enum Level {
1028
1029 // for convenience, we're reusing java.util.logging.Level int values
1030 // the mapping logic in sun.util.logging.PlatformLogger depends
1031 // on this.
1032 /**
1033 * A marker to indicate that all levels are enabled.
1034 * This level {@linkplain #getSeverity() severity} is
1035 * {@link Integer#MIN_VALUE}.
1036 */
1037 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
1038 /**
1039 * {@code TRACE} level: usually used to log diagnostic information.
1040 * This level {@linkplain #getSeverity() severity} is
1041 * {@code 400}.
1042 */
1043 TRACE(400), // typically mapped to/from j.u.l.Level.FINER
1044 /**
1045 * {@code DEBUG} level: usually used to log debug information traces.
1046 * This level {@linkplain #getSeverity() severity} is
1047 * {@code 500}.
1048 */
1049 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
1050 /**
1051 * {@code INFO} level: usually used to log information messages.
1052 * This level {@linkplain #getSeverity() severity} is
1053 * {@code 800}.
1054 */
1055 INFO(800), // typically mapped to/from j.u.l.Level.INFO
1056 /**
1057 * {@code WARNING} level: usually used to log warning messages.
1058 * This level {@linkplain #getSeverity() severity} is
1059 * {@code 900}.
1060 */
1061 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
1062 /**
1063 * {@code ERROR} level: usually used to log error messages.
1064 * This level {@linkplain #getSeverity() severity} is
1065 * {@code 1000}.
1066 */
1067 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
1068 /**
1069 * A marker to indicate that all levels are disabled.
1070 * This level {@linkplain #getSeverity() severity} is
1071 * {@link Integer#MAX_VALUE}.
1072 */
1073 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
1074
1075 private final int severity;
1076
1077 private Level(int severity) {
1078 this.severity = severity;
1079 }
1080
1081 /**
1082 * Returns the name of this level.
1083 * @return this level {@linkplain #name()}.
1084 */
1085 public final String getName() {
1086 return name();
1087 }
1088
1089 /**
1090 * Returns the severity of this level.
1091 * A higher severity means a more severe condition.
1092 * @return this level severity.
1093 */
1094 public final int getSeverity() {
1095 return severity;
1096 }
1097 }
1098
1099 /**
1100 * Returns the name of this logger.
1101 *
1102 * @return the logger name.
1103 */
1104 public String getName();
1105
1106 /**
1107 * Checks if a message of the given level would be logged by
1108 * this logger.
1109 *
1110 * @param level the log message level.
1111 * @return {@code true} if the given log message level is currently
1112 * being logged.
1113 *
1114 * @throws NullPointerException if {@code level} is {@code null}.
1115 */
1116 public boolean isLoggable(Level level);
1117
1118 /**
1119 * Logs a message.
1120 *
1121 * @implSpec The default implementation for this method calls
1122 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1123 *
1124 * @param level the log message level.
1125 * @param msg the string message (or a key in the message catalog, if
1126 * this logger is a {@link
1127 * LoggerFinder#getLocalizedLogger(java.lang.String,
1128 * java.util.ResourceBundle, java.lang.Module) localized logger});
1129 * can be {@code null}.
1130 *
1131 * @throws NullPointerException if {@code level} is {@code null}.
1132 */
1133 public default void log(Level level, String msg) {
1134 log(level, (ResourceBundle) null, msg, (Object[]) null);
1135 }
1136
1137 /**
1138 * Logs a lazily supplied message.
1139 *
1140 * If the logger is currently enabled for the given log message level
1141 * then a message is logged that is the result produced by the
1142 * given supplier function. Otherwise, the supplier is not operated on.
1143 *
1144 * @implSpec When logging is enabled for the given level, the default
1145 * implementation for this method calls
1146 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
1147 *
1148 * @param level the log message level.
1149 * @param msgSupplier a supplier function that produces a message.
1150 *
1151 * @throws NullPointerException if {@code level} is {@code null},
1152 * or {@code msgSupplier} is {@code null}.
1153 */
1154 public default void log(Level level, Supplier<String> msgSupplier) {
1155 Objects.requireNonNull(msgSupplier);
1156 if (isLoggable(Objects.requireNonNull(level))) {
1157 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1158 }
1159 }
1160
1161 /**
1162 * Logs a message produced from the given object.
1163 *
1164 * If the logger is currently enabled for the given log message level then
1165 * a message is logged that, by default, is the result produced from
1166 * calling toString on the given object.
1167 * Otherwise, the object is not operated on.
1168 *
1169 * @implSpec When logging is enabled for the given level, the default
1170 * implementation for this method calls
1171 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1172 *
1173 * @param level the log message level.
1174 * @param obj the object to log.
1175 *
1176 * @throws NullPointerException if {@code level} is {@code null}, or
1177 * {@code obj} is {@code null}.
1178 */
1179 public default void log(Level level, Object obj) {
1180 Objects.requireNonNull(obj);
1181 if (isLoggable(Objects.requireNonNull(level))) {
1182 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1183 }
1184 }
1185
1186 /**
1187 * Logs a message associated with a given throwable.
1188 *
1189 * @implSpec The default implementation for this method calls
1190 * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1191 *
1192 * @param level the log message level.
1193 * @param msg the string message (or a key in the message catalog, if
1194 * this logger is a {@link
1195 * LoggerFinder#getLocalizedLogger(java.lang.String,
1196 * java.util.ResourceBundle, java.lang.Module) localized logger});
1197 * can be {@code null}.
1198 * @param thrown a {@code Throwable} associated with the log message;
1199 * can be {@code null}.
1200 *
1201 * @throws NullPointerException if {@code level} is {@code null}.
1202 */
1203 public default void log(Level level, String msg, Throwable thrown) {
1204 this.log(level, null, msg, thrown);
1205 }
1206
1207 /**
1208 * Logs a lazily supplied message associated with a given throwable.
1209 *
1210 * If the logger is currently enabled for the given log message level
1211 * then a message is logged that is the result produced by the
1212 * given supplier function. Otherwise, the supplier is not operated on.
1213 *
1214 * @implSpec When logging is enabled for the given level, the default
1215 * implementation for this method calls
1216 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1217 *
1218 * @param level one of the log message level identifiers.
1219 * @param msgSupplier a supplier function that produces a message.
1220 * @param thrown a {@code Throwable} associated with log message;
1221 * can be {@code null}.
1222 *
1223 * @throws NullPointerException if {@code level} is {@code null}, or
1224 * {@code msgSupplier} is {@code null}.
1225 */
1226 public default void log(Level level, Supplier<String> msgSupplier,
1227 Throwable thrown) {
1228 Objects.requireNonNull(msgSupplier);
1229 if (isLoggable(Objects.requireNonNull(level))) {
1230 this.log(level, null, msgSupplier.get(), thrown);
1231 }
1232 }
1233
1234 /**
1235 * Logs a message with an optional list of parameters.
1236 *
1237 * @implSpec The default implementation for this method calls
1238 * {@code this.log(level, (ResourceBundle)null, format, params);}
1239 *
1240 * @param level one of the log message level identifiers.
1241 * @param format the string message format in {@link
1242 * java.text.MessageFormat} format, (or a key in the message
1243 * catalog, if this logger is a {@link
1244 * LoggerFinder#getLocalizedLogger(java.lang.String,
1245 * java.util.ResourceBundle, java.lang.Module) localized logger});
1246 * 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 default void log(Level level, String format, Object... params) {
1253 this.log(level, null, format, params);
1254 }
1255
1256 /**
1257 * Logs a localized message associated with a given throwable.
1258 *
1259 * If the given resource bundle is non-{@code null}, the {@code msg}
1260 * string is localized using the given resource bundle.
1261 * Otherwise the {@code msg} string is not localized.
1262 *
1263 * @param level the log message level.
1264 * @param bundle a resource bundle to localize {@code msg}; can be
1265 * {@code null}.
1266 * @param msg the string message (or a key in the message catalog,
1267 * if {@code bundle} is not {@code null}); can be {@code null}.
1268 * @param thrown a {@code Throwable} associated with the log message;
1269 * can be {@code null}.
1270 *
1271 * @throws NullPointerException if {@code level} is {@code null}.
1272 */
1273 public void log(Level level, ResourceBundle bundle, String msg,
1274 Throwable thrown);
1275
1276 /**
1277 * Logs a message with resource bundle and an optional list of
1278 * parameters.
1279 *
1280 * If the given resource bundle is non-{@code null}, the {@code format}
1281 * string is localized using the given resource bundle.
1282 * Otherwise the {@code format} string is not localized.
1283 *
1284 * @param level the log message level.
1285 * @param bundle a resource bundle to localize {@code format}; can be
1286 * {@code null}.
1287 * @param format the string message format in {@link
1288 * java.text.MessageFormat} format, (or a key in the message
1289 * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1290 * @param params an optional list of parameters to the message (may be
1291 * none).
1292 *
1293 * @throws NullPointerException if {@code level} is {@code null}.
1294 */
1295 public void log(Level level, ResourceBundle bundle, String format,
1296 Object... params);
1297 }
1298
1299 /**
1300 * The {@code LoggerFinder} service is responsible for creating, managing,
1301 * and configuring loggers to the underlying framework it uses.
1302 *
1303 * A logger finder is a concrete implementation of this class that has a
1304 * zero-argument constructor and implements the abstract methods defined
1305 * by this class.
1306 * The loggers returned from a logger finder are capable of routing log
1307 * messages to the logging backend this provider supports.
1308 * A given invocation of the Java Runtime maintains a single
1309 * system-wide LoggerFinder instance that is loaded as follows:
1310 * <ul>
1311 * <li>First it finds any custom {@code LoggerFinder} provider
1312 * using the {@link java.util.ServiceLoader} facility with the
1313 * {@linkplain ClassLoader#getSystemClassLoader() system class
1314 * loader}.</li>
1315 * <li>If no {@code LoggerFinder} provider is found, the system default
1316 * {@code LoggerFinder} implementation will be used.</li>
1317 * </ul>
1318 * <p>
1319 * An application can replace the logging backend
1320 * <i>even when the java.logging module is present</i>, by simply providing
1321 * and declaring an implementation of the {@link LoggerFinder} service.
1322 * <p>
1323 * <b>Default Implementation</b>
1324 * <p>
1325 * The system default {@code LoggerFinder} implementation uses
1326 * {@code java.util.logging} as the backend framework when the
1327 * {@code java.logging} module is present.
1328 * It returns a {@linkplain System.Logger logger} instance
1329 * that will route log messages to a {@link java.logging/java.util.logging.Logger
1330 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1331 * present, the default implementation will return a simple logger
1332 * instance that will route log messages of {@code INFO} level and above to
1333 * the console ({@code System.err}).
1334 * <p>
1335 * <b>Logging Configuration</b>
1336 * <p>
1337 * {@linkplain Logger Logger} instances obtained from the
1338 * {@code LoggerFinder} factory methods are not directly configurable by
1339 * the application. Configuration is the responsibility of the underlying
1340 * logging backend, and usually requires using APIs specific to that backend.
1341 * <p>For the default {@code LoggerFinder} implementation
1342 * using {@code java.util.logging} as its backend, refer to
1343 * {@link java.logging/java.util.logging java.util.logging} for logging configuration.
1344 * For the default {@code LoggerFinder} implementation returning simple loggers
1345 * when the {@code java.logging} module is absent, the configuration
1346 * is implementation dependent.
1347 * <p>
1348 * Usually an application that uses a logging framework will log messages
1349 * through a logger facade defined (or supported) by that framework.
1350 * Applications that wish to use an external framework should log
1351 * through the facade associated with that framework.
1352 * <p>
1353 * A system class that needs to log messages will typically obtain
1354 * a {@link System.Logger} instance to route messages to the logging
1355 * framework selected by the application.
1356 * <p>
1357 * Libraries and classes that only need loggers to produce log messages
1358 * should not attempt to configure loggers by themselves, as that
1359 * would make them dependent from a specific implementation of the
1360 * {@code LoggerFinder} service.
1361 * <p>
1362 * <b>Message Levels and Mapping to backend levels</b>
1363 * <p>
1364 * A logger finder is responsible for mapping from a {@code
1365 * System.Logger.Level} to a level supported by the logging backend it uses.
1366 * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1367 * maps {@code System.Logger} levels to
1368 * {@linkplain java.logging/java.util.logging.Level java.util.logging} levels
1369 * of corresponding severity - as described in {@link Logger.Level
1370 * Logger.Level}.
1371 *
1372 * @see java.lang.System
1373 * @see java.lang.System.Logger
1374 *
1375 * @since 9
1376 */
1377 @SuppressWarnings("doclint:reference") // cross-module links
1378 public abstract static class LoggerFinder {
1379 /**
1380 * The {@code RuntimePermission("loggerFinder")} is
1381 * necessary to subclass and instantiate the {@code LoggerFinder} class,
1382 * as well as to obtain loggers from an instance of that class.
1383 */
1384 static final RuntimePermission LOGGERFINDER_PERMISSION =
1385 new RuntimePermission("loggerFinder");
1386
1387 /**
1388 * Creates a new instance of {@code LoggerFinder}.
1389 *
1390 * @implNote It is recommended that a {@code LoggerFinder} service
1391 * implementation does not perform any heavy initialization in its
1392 * constructor, in order to avoid possible risks of deadlock or class
1393 * loading cycles during the instantiation of the service provider.
1394 */
1395 protected LoggerFinder() {
1396 this(checkPermission());
1397 }
1398
1399 private LoggerFinder(Void unused) {
1400 // nothing to do.
1401 }
1402
1403 private static Void checkPermission() {
1404 @SuppressWarnings("removal")
1405 final SecurityManager sm = System.getSecurityManager();
1406 if (sm != null) {
1407 sm.checkPermission(LOGGERFINDER_PERMISSION);
1408 }
1409 return null;
1410 }
1411
1412 /**
1413 * Returns an instance of {@link Logger Logger}
1414 * for the given {@code module}.
1415 *
1416 * @param name the name of the logger.
1417 * @param module the module for which the logger is being requested.
1418 *
1419 * @return a {@link Logger logger} suitable for use within the given
1420 * module.
1421 * @throws NullPointerException if {@code name} is {@code null} or
1422 * {@code module} is {@code null}.
1423 */
1424 public abstract Logger getLogger(String name, Module module);
1425
1426 /**
1427 * Returns a localizable instance of {@link Logger Logger}
1428 * for the given {@code module}.
1429 * The returned logger will use the provided resource bundle for
1430 * message localization.
1431 *
1432 * @implSpec By default, this method calls {@link
1433 * #getLogger(java.lang.String, java.lang.Module)
1434 * this.getLogger(name, module)} to obtain a logger, then wraps that
1435 * logger in a {@link Logger} instance where all methods that do not
1436 * take a {@link ResourceBundle} as parameter are redirected to one
1437 * which does - passing the given {@code bundle} for
1438 * localization. So for instance, a call to {@link
1439 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1440 * will end up as a call to {@link
1441 * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1442 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1443 * logger instance.
1444 * Note however that by default, string messages returned by {@link
1445 * java.util.function.Supplier Supplier<String>} will not be
1446 * localized, as it is assumed that such strings are messages which are
1447 * already constructed, rather than keys in a resource bundle.
1448 * <p>
1449 * An implementation of {@code LoggerFinder} may override this method,
1450 * for example, when the underlying logging backend provides its own
1451 * mechanism for localizing log messages, then such a
1452 * {@code LoggerFinder} would be free to return a logger
1453 * that makes direct use of the mechanism provided by the backend.
1454 *
1455 * @param name the name of the logger.
1456 * @param bundle a resource bundle; can be {@code null}.
1457 * @param module the module for which the logger is being requested.
1458 * @return an instance of {@link Logger Logger} which will use the
1459 * provided resource bundle for message localization.
1460 *
1461 * @throws NullPointerException if {@code name} is {@code null} or
1462 * {@code module} is {@code null}.
1463 */
1464 public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1465 Module module) {
1466 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1467 }
1468
1469 /**
1470 * Returns the {@code LoggerFinder} instance. There is one
1471 * single system-wide {@code LoggerFinder} instance in
1472 * the Java Runtime. See the class specification of how the
1473 * {@link LoggerFinder LoggerFinder} implementation is located and
1474 * loaded.
1475 *
1476 * @return the {@link LoggerFinder LoggerFinder} instance.
1477 */
1478 public static LoggerFinder getLoggerFinder() {
1479 @SuppressWarnings("removal")
1480 final SecurityManager sm = System.getSecurityManager();
1481 if (sm != null) {
1482 sm.checkPermission(LOGGERFINDER_PERMISSION);
1483 }
1484 return accessProvider();
1485 }
1486
1487
1488 private static volatile LoggerFinder service;
1489 @SuppressWarnings("removal")
1490 static LoggerFinder accessProvider() {
1491 // We do not need to synchronize: LoggerFinderLoader will
1492 // always return the same instance, so if we don't have it,
1493 // just fetch it again.
1494 LoggerFinder finder = service;
1495 if (finder == null) {
1496 PrivilegedAction<LoggerFinder> pa =
1497 () -> LoggerFinderLoader.getLoggerFinder();
1498 finder = AccessController.doPrivileged(pa, null,
1499 LOGGERFINDER_PERMISSION);
1500 if (finder instanceof TemporaryLoggerFinder) return finder;
1501 service = finder;
1502 }
1503 return finder;
1504 }
1505
1506 }
1507
1508
1509 /**
1510 * Returns an instance of {@link Logger Logger} for the caller's
1511 * use.
1512 *
1513 * @implSpec
1514 * Instances returned by this method route messages to loggers
1515 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1516 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1517 * {@code module} is the caller's module.
1518 * In cases where {@code System.getLogger} is called from a context where
1519 * there is no caller frame on the stack (e.g when called directly
1520 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1521 * To obtain a logger in such a context, use an auxiliary class that will
1522 * implicitly be identified as the caller, or use the system {@link
1523 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1524 * Note that doing the latter may eagerly initialize the underlying
1525 * logging system.
1526 *
1527 * @apiNote
1528 * This method may defer calling the {@link
1529 * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1530 * LoggerFinder.getLogger} method to create an actual logger supplied by
1531 * the logging backend, for instance, to allow loggers to be obtained during
1532 * the system initialization time.
1533 *
1534 * @param name the name of the logger.
1535 * @return an instance of {@link Logger} that can be used by the calling
1536 * class.
1537 * @throws NullPointerException if {@code name} is {@code null}.
1538 * @throws IllegalCallerException if there is no Java caller frame on the
1539 * stack.
1540 *
1541 * @since 9
1542 */
1543 @CallerSensitive
1544 public static Logger getLogger(String name) {
1545 Objects.requireNonNull(name);
1546 final Class<?> caller = Reflection.getCallerClass();
1547 if (caller == null) {
1548 throw new IllegalCallerException("no caller frame");
1549 }
1550 return LazyLoggers.getLogger(name, caller.getModule());
1551 }
1552
1553 /**
1554 * Returns a localizable instance of {@link Logger
1555 * Logger} for the caller's use.
1556 * The returned logger will use the provided resource bundle for message
1557 * localization.
1558 *
1559 * @implSpec
1560 * The returned logger will perform message localization as specified
1561 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1562 * java.util.ResourceBundle, java.lang.Module)
1563 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1564 * {@code module} is the caller's module.
1565 * In cases where {@code System.getLogger} is called from a context where
1566 * there is no caller frame on the stack (e.g when called directly
1567 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1568 * To obtain a logger in such a context, use an auxiliary class that
1569 * will implicitly be identified as the caller, or use the system {@link
1570 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1571 * Note that doing the latter may eagerly initialize the underlying
1572 * logging system.
1573 *
1574 * @apiNote
1575 * This method is intended to be used after the system is fully initialized.
1576 * This method may trigger the immediate loading and initialization
1577 * of the {@link LoggerFinder} service, which may cause issues if the
1578 * Java Runtime is not ready to initialize the concrete service
1579 * implementation yet.
1580 * System classes which may be loaded early in the boot sequence and
1581 * need to log localized messages should create a logger using
1582 * {@link #getLogger(java.lang.String)} and then use the log methods that
1583 * take a resource bundle as parameter.
1584 *
1585 * @param name the name of the logger.
1586 * @param bundle a resource bundle.
1587 * @return an instance of {@link Logger} which will use the provided
1588 * resource bundle for message localization.
1589 * @throws NullPointerException if {@code name} is {@code null} or
1590 * {@code bundle} is {@code null}.
1591 * @throws IllegalCallerException if there is no Java caller frame on the
1592 * stack.
1593 *
1594 * @since 9
1595 */
1596 @SuppressWarnings("removal")
1597 @CallerSensitive
1598 public static Logger getLogger(String name, ResourceBundle bundle) {
1599 final ResourceBundle rb = Objects.requireNonNull(bundle);
1600 Objects.requireNonNull(name);
1601 final Class<?> caller = Reflection.getCallerClass();
1602 if (caller == null) {
1603 throw new IllegalCallerException("no caller frame");
1604 }
1605 final SecurityManager sm = System.getSecurityManager();
1606 // We don't use LazyLoggers if a resource bundle is specified.
1607 // Bootstrap sensitive classes in the JDK do not use resource bundles
1608 // when logging. This could be revisited later, if it needs to.
1609 if (sm != null) {
1610 final PrivilegedAction<Logger> pa =
1611 () -> LoggerFinder.accessProvider()
1612 .getLocalizedLogger(name, rb, caller.getModule());
1613 return AccessController.doPrivileged(pa, null,
1614 LoggerFinder.LOGGERFINDER_PERMISSION);
1615 }
1616 return LoggerFinder.accessProvider()
1617 .getLocalizedLogger(name, rb, caller.getModule());
1618 }
1619
1620 /**
1621 * Initiates the {@linkplain Runtime##shutdown shutdown sequence} of the Java Virtual
1622 * Machine. This method initiates the shutdown sequence (if it is not already initiated)
1623 * and then blocks indefinitely. This method neither returns nor throws an exception;
1624 * that is, it does not complete either normally or abruptly.
1625 * <p>
1626 * The argument serves as a status code. By convention, a nonzero status code
1627 * indicates abnormal termination.
1628 * <p>
1629 * The call {@code System.exit(n)} is effectively equivalent to the call:
1630 * {@snippet :
1631 * Runtime.getRuntime().exit(n)
1632 * }
1633 *
1634 * @implNote
1635 * The initiation of the shutdown sequence is logged by {@link Runtime#exit(int)}.
1636 *
1637 * @param status exit status.
1638 * @see java.lang.Runtime#exit(int)
1639 */
1640 public static void exit(int status) {
1641 Runtime.getRuntime().exit(status);
1642 }
1643
1644 /**
1645 * Runs the garbage collector in the Java Virtual Machine.
1646 * <p>
1647 * Calling the {@code gc} method suggests that the Java Virtual Machine
1648 * expend effort toward recycling unused objects in order to
1649 * make the memory they currently occupy available for reuse
1650 * by the Java Virtual Machine.
1651 * When control returns from the method call, the Java Virtual Machine
1652 * has made a best effort to reclaim space from all unused objects.
1653 * There is no guarantee that this effort will recycle any particular
1654 * number of unused objects, reclaim any particular amount of space, or
1655 * complete at any particular time, if at all, before the method returns or ever.
1656 * There is also no guarantee that this effort will determine
1657 * the change of reachability in any particular number of objects,
1658 * or that any particular number of {@link java.lang.ref.Reference Reference}
1659 * objects will be cleared and enqueued.
1660 *
1661 * <p>
1662 * The call {@code System.gc()} is effectively equivalent to the
1663 * call:
1664 * <blockquote><pre>
1665 * Runtime.getRuntime().gc()
1666 * </pre></blockquote>
1667 *
1668 * @see java.lang.Runtime#gc()
1669 */
1670 public static void gc() {
1671 Runtime.getRuntime().gc();
1672 }
1673
1674 /**
1675 * Runs the finalization methods of any objects pending finalization.
1676 *
1677 * Calling this method suggests that the Java Virtual Machine expend
1678 * effort toward running the {@code finalize} methods of objects
1679 * that have been found to be discarded but whose {@code finalize}
1680 * methods have not yet been run. When control returns from the
1681 * method call, the Java Virtual Machine has made a best effort to
1682 * complete all outstanding finalizations.
1683 * <p>
1684 * The call {@code System.runFinalization()} is effectively
1685 * equivalent to the call:
1686 * <blockquote><pre>
1687 * Runtime.getRuntime().runFinalization()
1688 * </pre></blockquote>
1689 *
1690 * @deprecated Finalization has been deprecated for removal. See
1691 * {@link java.lang.Object#finalize} for background information and details
1692 * about migration options.
1693 * <p>
1694 * When running in a JVM in which finalization has been disabled or removed,
1695 * no objects will be pending finalization, so this method does nothing.
1696 *
1697 * @see java.lang.Runtime#runFinalization()
1698 * @jls 12.6 Finalization of Class Instances
1699 */
1700 @Deprecated(since="18", forRemoval=true)
1701 @SuppressWarnings("removal")
1702 public static void runFinalization() {
1703 Runtime.getRuntime().runFinalization();
1704 }
1705
1706 /**
1707 * Loads the native library specified by the filename argument. The filename
1708 * argument must be an absolute path name.
1709 *
1710 * If the filename argument, when stripped of any platform-specific library
1711 * prefix, path, and file extension, indicates a library whose name is,
1712 * for example, L, and a native library called L is statically linked
1713 * with the VM, then the JNI_OnLoad_L function exported by the library
1714 * is invoked rather than attempting to load a dynamic library.
1715 * A filename matching the argument does not have to exist in the
1716 * file system.
1717 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1718 * for more details.
1719 *
1720 * Otherwise, the filename argument is mapped to a native library image in
1721 * an implementation-dependent manner.
1722 *
1723 * <p>
1724 * The call {@code System.load(name)} is effectively equivalent
1725 * to the call:
1726 * <blockquote><pre>
1727 * Runtime.getRuntime().load(name)
1728 * </pre></blockquote>
1729 *
1730 * @param filename the file to load.
1731 * @throws UnsatisfiedLinkError if either the filename is not an
1732 * absolute path name, the native library is not statically
1733 * linked with the VM, or the library cannot be mapped to
1734 * a native library image by the host system.
1735 * @throws NullPointerException if {@code filename} is {@code null}
1736 * @throws IllegalCallerException if the caller is in a module that
1737 * does not have native access enabled.
1738 *
1739 * @spec jni/index.html Java Native Interface Specification
1740 * @see java.lang.Runtime#load(java.lang.String)
1741 */
1742 @CallerSensitive
1743 @Restricted
1744 public static void load(String filename) {
1745 Class<?> caller = Reflection.getCallerClass();
1746 Reflection.ensureNativeAccess(caller, System.class, "load", false);
1747 Runtime.getRuntime().load0(caller, filename);
1748 }
1749
1750 /**
1751 * Loads the native library specified by the {@code libname}
1752 * argument. The {@code libname} argument must not contain any platform
1753 * specific prefix, file extension or path. If a native library
1754 * called {@code libname} is statically linked with the VM, then the
1755 * JNI_OnLoad_{@code libname} function exported by the library is invoked.
1756 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1757 * for more details.
1758 *
1759 * Otherwise, the libname argument is loaded from a system library
1760 * location and mapped to a native library image in an
1761 * implementation-dependent manner.
1762 * <p>
1763 * The call {@code System.loadLibrary(name)} is effectively
1764 * equivalent to the call
1765 * <blockquote><pre>
1766 * Runtime.getRuntime().loadLibrary(name)
1767 * </pre></blockquote>
1768 *
1769 * @param libname the name of the library.
1770 * @throws UnsatisfiedLinkError if either the libname argument
1771 * contains a file path, the native library is not statically
1772 * linked with the VM, or the library cannot be mapped to a
1773 * native library image by the host system.
1774 * @throws NullPointerException if {@code libname} is {@code null}
1775 * @throws IllegalCallerException if the caller is in a module that
1776 * does not have native access enabled.
1777 *
1778 * @spec jni/index.html Java Native Interface Specification
1779 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1780 */
1781 @CallerSensitive
1782 @Restricted
1783 public static void loadLibrary(String libname) {
1784 Class<?> caller = Reflection.getCallerClass();
1785 Reflection.ensureNativeAccess(caller, System.class, "loadLibrary", false);
1786 Runtime.getRuntime().loadLibrary0(caller, libname);
1787 }
1788
1789 /**
1790 * Maps a library name into a platform-specific string representing
1791 * a native library.
1792 *
1793 * @param libname the name of the library.
1794 * @return a platform-dependent native library name.
1795 * @throws NullPointerException if {@code libname} is {@code null}
1796 * @see java.lang.System#loadLibrary(java.lang.String)
1797 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1798 * @since 1.2
1799 */
1800 public static native String mapLibraryName(String libname);
1801
1802 /**
1803 * Create PrintStream for stdout/err based on encoding.
1804 */
1805 private static PrintStream newPrintStream(OutputStream out, String enc) {
1806 if (enc != null) {
1807 return new PrintStream(new BufferedOutputStream(out, 128), true,
1808 Charset.forName(enc, UTF_8.INSTANCE));
1809 }
1810 return new PrintStream(new BufferedOutputStream(out, 128), true);
1811 }
1812
1813 /**
1814 * Logs an exception/error at initialization time to stdout or stderr.
1815 *
1816 * @param printToStderr to print to stderr rather than stdout
1817 * @param printStackTrace to print the stack trace
1818 * @param msg the message to print before the exception, can be {@code null}
1819 * @param e the exception or error
1820 */
1821 private static void logInitException(boolean printToStderr,
1822 boolean printStackTrace,
1823 String msg,
1824 Throwable e) {
1825 if (VM.initLevel() < 1) {
1826 throw new InternalError("system classes not initialized");
1827 }
1828 PrintStream log = (printToStderr) ? err : out;
1829 if (msg != null) {
1830 log.println(msg);
1831 }
1832 if (printStackTrace) {
1833 e.printStackTrace(log);
1834 } else {
1835 log.println(e);
1836 for (Throwable suppressed : e.getSuppressed()) {
1837 log.println("Suppressed: " + suppressed);
1838 }
1839 Throwable cause = e.getCause();
1840 if (cause != null) {
1841 log.println("Caused by: " + cause);
1842 }
1843 }
1844 }
1845
1846 /**
1847 * Create the Properties object from a map - masking out system properties
1848 * that are not intended for public access.
1849 */
1850 private static Properties createProperties(Map<String, String> initialProps) {
1851 Properties properties = new Properties(initialProps.size());
1852 for (var entry : initialProps.entrySet()) {
1853 String prop = entry.getKey();
1854 switch (prop) {
1855 // Do not add private system properties to the Properties
1856 case "sun.nio.MaxDirectMemorySize":
1857 case "sun.nio.PageAlignDirectMemory":
1858 // used by java.lang.Integer.IntegerCache
1859 case "java.lang.Integer.IntegerCache.high":
1860 // used by sun.launcher.LauncherHelper
1861 case "sun.java.launcher.diag":
1862 // used by jdk.internal.loader.ClassLoaders
1863 case "jdk.boot.class.path.append":
1864 break;
1865 default:
1866 properties.put(prop, entry.getValue());
1867 }
1868 }
1869 return properties;
1870 }
1871
1872 /**
1873 * Initialize the system class. Called after thread initialization.
1874 */
1875 private static void initPhase1() {
1876
1877 // register the shared secrets - do this first, since SystemProps.initProperties
1878 // might initialize CharsetDecoders that rely on it
1879 setJavaLangAccess();
1880
1881 // VM might invoke JNU_NewStringPlatform() to set those encoding
1882 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1883 // during "props" initialization.
1884 // The charset is initialized in System.c and does not depend on the Properties.
1885 Map<String, String> tempProps = SystemProps.initProperties();
1886 VersionProps.init(tempProps);
1887
1888 // There are certain system configurations that may be controlled by
1889 // VM options such as the maximum amount of direct memory and
1890 // Integer cache size used to support the object identity semantics
1891 // of autoboxing. Typically, the library will obtain these values
1892 // from the properties set by the VM. If the properties are for
1893 // internal implementation use only, these properties should be
1894 // masked from the system properties.
1895 //
1896 // Save a private copy of the system properties object that
1897 // can only be accessed by the internal implementation.
1898 VM.saveProperties(tempProps);
1899 props = createProperties(tempProps);
1900
1901 // Check if sun.jnu.encoding is supported. If not, replace it with UTF-8.
1902 var jnuEncoding = props.getProperty("sun.jnu.encoding");
1903 if (jnuEncoding == null || !Charset.isSupported(jnuEncoding)) {
1904 notSupportedJnuEncoding = jnuEncoding == null ? "null" : jnuEncoding;
1905 props.setProperty("sun.jnu.encoding", "UTF-8");
1906 }
1907
1908 StaticProperty.javaHome(); // Load StaticProperty to cache the property values
1909
1910 lineSeparator = props.getProperty("line.separator");
1911
1912 FileInputStream fdIn = new In(FileDescriptor.in);
1913 FileOutputStream fdOut = new Out(FileDescriptor.out);
1914 FileOutputStream fdErr = new Out(FileDescriptor.err);
1915 initialIn = new BufferedInputStream(fdIn);
1916 setIn0(initialIn);
1917 // stdout/err.encoding are set when the VM is associated with the terminal,
1918 // thus they are equivalent to Console.charset(), otherwise the encodings
1919 // of those properties default to native.encoding
1920 setOut0(newPrintStream(fdOut, props.getProperty("stdout.encoding")));
1921 initialErr = newPrintStream(fdErr, props.getProperty("stderr.encoding"));
1922 setErr0(initialErr);
1923
1924 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1925 Terminator.setup();
1926
1927 // Initialize any miscellaneous operating system settings that need to be
1928 // set for the class libraries. Currently this is no-op everywhere except
1929 // for Windows where the process-wide error mode is set before the java.io
1930 // classes are used.
1931 VM.initializeOSEnvironment();
1932
1933 // start Finalizer and Reference Handler threads
1934 SharedSecrets.getJavaLangRefAccess().startThreads();
1935
1936 // system properties, java.lang and other core classes are now initialized
1937 VM.initLevel(1);
1938 }
1939
1940 /**
1941 * System.in.
1942 */
1943 private static class In extends FileInputStream {
1944 In(FileDescriptor fd) {
1945 super(fd);
1946 }
1947
1948 @Override
1949 public int read() throws IOException {
1950 boolean attempted = Blocker.begin();
1951 try {
1952 return super.read();
1953 } finally {
1954 Blocker.end(attempted);
1955 }
1956 }
1957
1958 @Override
1959 public int read(byte[] b) throws IOException {
1960 boolean attempted = Blocker.begin();
1961 try {
1962 return super.read(b);
1963 } finally {
1964 Blocker.end(attempted);
1965 }
1966 }
1967
1968 @Override
1969 public int read(byte[] b, int off, int len) throws IOException {
1970 boolean attempted = Blocker.begin();
1971 try {
1972 return super.read(b, off, len);
1973 } finally {
1974 Blocker.end(attempted);
1975 }
1976 }
1977 }
1978
1979 /**
1980 * System.out/System.err wrap this output stream.
1981 */
1982 private static class Out extends FileOutputStream {
1983 Out(FileDescriptor fd) {
1984 super(fd);
1985 }
1986
1987 @Override
1988 public void write(int b) throws IOException {
1989 boolean attempted = Blocker.begin();
1990 try {
1991 super.write(b);
1992 } finally {
1993 Blocker.end(attempted);
1994 }
1995 }
1996
1997 @Override
1998 public void write(byte[] b) throws IOException {
1999 boolean attempted = Blocker.begin();
2000 try {
2001 super.write(b);
2002 } finally {
2003 Blocker.end(attempted);
2004 }
2005 }
2006
2007 @Override
2008 public void write(byte[] b, int off, int len) throws IOException {
2009 boolean attempted = Blocker.begin();
2010 try {
2011 super.write(b, off, len);
2012 } finally {
2013 Blocker.end(attempted);
2014 }
2015 }
2016 }
2017
2018 // @see #initPhase2()
2019 static ModuleLayer bootLayer;
2020
2021 /*
2022 * Invoked by VM. Phase 2 module system initialization.
2023 * Only classes in java.base can be loaded in this phase.
2024 *
2025 * @param printToStderr print exceptions to stderr rather than stdout
2026 * @param printStackTrace print stack trace when exception occurs
2027 *
2028 * @return JNI_OK for success, JNI_ERR for failure
2029 */
2030 private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
2031
2032 try {
2033 bootLayer = ModuleBootstrap.boot();
2034 } catch (Exception | Error e) {
2035 logInitException(printToStderr, printStackTrace,
2036 "Error occurred during initialization of boot layer", e);
2037 return -1; // JNI_ERR
2038 }
2039
2040 // module system initialized
2041 VM.initLevel(2);
2042
2043 return 0; // JNI_OK
2044 }
2045
2046 /*
2047 * Invoked by VM. Phase 3 is the final system initialization:
2048 * 1. set system class loader
2049 * 2. set TCCL
2050 *
2051 * This method must be called after the module system initialization.
2052 */
2053 private static void initPhase3() {
2054
2055 // Emit a warning if java.io.tmpdir is set via the command line
2056 // to a directory that doesn't exist
2057 if (SystemProps.isBadIoTmpdir()) {
2058 System.err.println("WARNING: java.io.tmpdir directory does not exist");
2059 }
2060
2061 String smProp = System.getProperty("java.security.manager");
2062 if (smProp != null) {
2063 switch (smProp) {
2064 case "disallow":
2065 break;
2066 case "allow":
2067 case "":
2068 case "default":
2069 default:
2070 throw new Error("A command line option has attempted to allow or enable the Security Manager."
2071 + " Enabling a Security Manager is not supported.");
2072 }
2073 }
2074
2075 // Emit a warning if `sun.jnu.encoding` is not supported.
2076 if (notSupportedJnuEncoding != null) {
2077 System.err.println(
2078 "WARNING: The encoding of the underlying platform's" +
2079 " file system is not supported: " +
2080 notSupportedJnuEncoding);
2081 }
2082
2083 // initializing the system class loader
2084 VM.initLevel(3);
2085
2086 // system class loader initialized
2087 ClassLoader scl = ClassLoader.initSystemClassLoader();
2088
2089 // set TCCL
2090 Thread.currentThread().setContextClassLoader(scl);
2091
2092 // system is fully initialized
2093 VM.initLevel(4);
2094 }
2095
2096 private static void setJavaLangAccess() {
2097 // Allow privileged classes outside of java.lang
2098 SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
2099 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
2100 return klass.getDeclaredPublicMethods(name, parameterTypes);
2101 }
2102 public Method findMethod(Class<?> klass, boolean publicOnly, String name, Class<?>... parameterTypes) {
2103 return klass.findMethod(publicOnly, name, parameterTypes);
2104 }
2105 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
2106 return klass.getConstantPool();
2107 }
2108 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
2109 return klass.casAnnotationType(oldType, newType);
2110 }
2111 public AnnotationType getAnnotationType(Class<?> klass) {
2112 return klass.getAnnotationType();
2113 }
2114 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2115 return klass.getDeclaredAnnotationMap();
2116 }
2117 public byte[] getRawClassAnnotations(Class<?> klass) {
2118 return klass.getRawAnnotations();
2119 }
2120 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2121 return klass.getRawTypeAnnotations();
2122 }
2123 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2124 return Class.getExecutableTypeAnnotationBytes(executable);
2125 }
2126 public <E extends Enum<E>>
2127 E[] getEnumConstantsShared(Class<E> klass) {
2128 return klass.getEnumConstantsShared();
2129 }
2130 public void blockedOn(Interruptible b) {
2131 Thread.currentThread().blockedOn(b);
2132 }
2133 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2134 Shutdown.add(slot, registerShutdownInProgress, hook);
2135 }
2136 @SuppressWarnings("removal")
2137 public void invokeFinalize(Object o) throws Throwable {
2138 o.finalize();
2139 }
2140 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2141 return cl.createOrGetClassLoaderValueMap();
2142 }
2143 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2144 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2145 }
2146 public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd,
2147 boolean initialize, int flags, Object classData) {
2148 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData);
2149 }
2150 public Class<?> findBootstrapClassOrNull(String name) {
2151 return ClassLoader.findBootstrapClassOrNull(name);
2152 }
2153 public Package definePackage(ClassLoader cl, String name, Module module) {
2154 return cl.definePackage(name, module);
2155 }
2156 public Module defineModule(ClassLoader loader,
2157 ModuleDescriptor descriptor,
2158 URI uri) {
2159 return new Module(null, loader, descriptor, uri);
2160 }
2161 public Module defineUnnamedModule(ClassLoader loader) {
2162 return new Module(loader);
2163 }
2164 public void addReads(Module m1, Module m2) {
2165 m1.implAddReads(m2);
2166 }
2167 public void addReadsAllUnnamed(Module m) {
2168 m.implAddReadsAllUnnamed();
2169 }
2170 public void addExports(Module m, String pn) {
2171 m.implAddExports(pn);
2172 }
2173 public void addExports(Module m, String pn, Module other) {
2174 m.implAddExports(pn, other);
2175 }
2176 public void addExportsToAllUnnamed(Module m, String pn) {
2177 m.implAddExportsToAllUnnamed(pn);
2178 }
2179 public void addOpens(Module m, String pn, Module other) {
2180 m.implAddOpens(pn, other);
2181 }
2182 public void addOpensToAllUnnamed(Module m, String pn) {
2183 m.implAddOpensToAllUnnamed(pn);
2184 }
2185 public void addOpensToAllUnnamed(Module m, Set<String> concealedPackages, Set<String> exportedPackages) {
2186 m.implAddOpensToAllUnnamed(concealedPackages, exportedPackages);
2187 }
2188 public void addUses(Module m, Class<?> service) {
2189 m.implAddUses(service);
2190 }
2191 public boolean isReflectivelyExported(Module m, String pn, Module other) {
2192 return m.isReflectivelyExported(pn, other);
2193 }
2194 public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2195 return m.isReflectivelyOpened(pn, other);
2196 }
2197 public Module addEnableNativeAccess(Module m) {
2198 return m.implAddEnableNativeAccess();
2199 }
2200 public boolean addEnableNativeAccess(ModuleLayer layer, String name) {
2201 return layer.addEnableNativeAccess(name);
2202 }
2203 public void addEnableNativeAccessToAllUnnamed() {
2204 Module.implAddEnableNativeAccessToAllUnnamed();
2205 }
2206 public void ensureNativeAccess(Module m, Class<?> owner, String methodName, Class<?> currentClass, boolean jni) {
2207 m.ensureNativeAccess(owner, methodName, currentClass, jni);
2208 }
2209 public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2210 return layer.getServicesCatalog();
2211 }
2212 public void bindToLoader(ModuleLayer layer, ClassLoader loader) {
2213 layer.bindToLoader(loader);
2214 }
2215 public Stream<ModuleLayer> layers(ModuleLayer layer) {
2216 return layer.layers();
2217 }
2218 public Stream<ModuleLayer> layers(ClassLoader loader) {
2219 return ModuleLayer.layers(loader);
2220 }
2221
2222 public int countPositives(byte[] bytes, int offset, int length) {
2223 return StringCoding.countPositives(bytes, offset, length);
2224 }
2225 public int countNonZeroAscii(String s) {
2226 return StringCoding.countNonZeroAscii(s);
2227 }
2228 public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
2229 return String.newStringNoRepl(bytes, cs);
2230 }
2231 public char getUTF16Char(byte[] bytes, int index) {
2232 return StringUTF16.getChar(bytes, index);
2233 }
2234 public void putCharUTF16(byte[] bytes, int index, int ch) {
2235 StringUTF16.putChar(bytes, index, ch);
2236 }
2237 public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2238 return String.getBytesNoRepl(s, cs);
2239 }
2240
2241 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2242 return String.newStringUTF8NoRepl(bytes, off, len, true);
2243 }
2244
2245 public byte[] getBytesUTF8NoRepl(String s) {
2246 return String.getBytesUTF8NoRepl(s);
2247 }
2248
2249 public void inflateBytesToChars(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2250 StringLatin1.inflate(src, srcOff, dst, dstOff, len);
2251 }
2252
2253 public int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2254 return String.decodeASCII(src, srcOff, dst, dstOff, len);
2255 }
2256
2257 public int encodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len) {
2258 return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
2259 }
2260
2261 public InputStream initialSystemIn() {
2262 return initialIn;
2263 }
2264
2265 public PrintStream initialSystemErr() {
2266 return initialErr;
2267 }
2268
2269 public void setCause(Throwable t, Throwable cause) {
2270 t.setCause(cause);
2271 }
2272
2273 public ProtectionDomain protectionDomain(Class<?> c) {
2274 return c.protectionDomain();
2275 }
2276
2277 public MethodHandle stringConcatHelper(String name, MethodType methodType) {
2278 return StringConcatHelper.lookupStatic(name, methodType);
2279 }
2280
2281 public long stringConcatInitialCoder() {
2282 return StringConcatHelper.initialCoder();
2283 }
2284
2285 public long stringConcatMix(long lengthCoder, String constant) {
2286 return StringConcatHelper.mix(lengthCoder, constant);
2287 }
2288
2289 public long stringConcatMix(long lengthCoder, char value) {
2290 return StringConcatHelper.mix(lengthCoder, value);
2291 }
2292
2293 public Object stringConcat1(String[] constants) {
2294 return new StringConcatHelper.Concat1(constants);
2295 }
2296
2297 public byte stringInitCoder() {
2298 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
2299 }
2300
2301 public byte stringCoder(String str) {
2302 return str.coder();
2303 }
2304
2305 public int getCharsLatin1(long i, int index, byte[] buf) {
2306 return StringLatin1.getChars(i, index, buf);
2307 }
2308
2309 public int getCharsUTF16(long i, int index, byte[] buf) {
2310 return StringUTF16.getChars(i, index, buf);
2311 }
2312
2313 public String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
2314 return String.join(prefix, suffix, delimiter, elements, size);
2315 }
2316
2317 public String concat(String prefix, Object value, String suffix) {
2318 return StringConcatHelper.concat(prefix, value, suffix);
2319 }
2320
2321 public Object classData(Class<?> c) {
2322 return c.getClassData();
2323 }
2324
2325 @Override
2326 public NativeLibraries nativeLibrariesFor(ClassLoader loader) {
2327 return ClassLoader.nativeLibrariesFor(loader);
2328 }
2329
2330 @Override
2331 public void exit(int statusCode) {
2332 Shutdown.exit(statusCode);
2333 }
2334
2335 public Thread[] getAllThreads() {
2336 return Thread.getAllThreads();
2337 }
2338
2339 public ThreadContainer threadContainer(Thread thread) {
2340 return thread.threadContainer();
2341 }
2342
2343 public void start(Thread thread, ThreadContainer container) {
2344 thread.start(container);
2345 }
2346
2347 public StackableScope headStackableScope(Thread thread) {
2348 return thread.headStackableScopes();
2349 }
2350
2351 public void setHeadStackableScope(StackableScope scope) {
2352 Thread.setHeadStackableScope(scope);
2353 }
2354
2355 public Thread currentCarrierThread() {
2356 return Thread.currentCarrierThread();
2357 }
2358
2359 public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
2360 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
2361 }
2362
2363 public <T> void setCarrierThreadLocal(CarrierThreadLocal<T> local, T value) {
2364 ((ThreadLocal<T>)local).setCarrierThreadLocal(value);
2365 }
2366
2367 public void removeCarrierThreadLocal(CarrierThreadLocal<?> local) {
2368 ((ThreadLocal<?>)local).removeCarrierThreadLocal();
2369 }
2370
2371 public boolean isCarrierThreadLocalPresent(CarrierThreadLocal<?> local) {
2372 return ((ThreadLocal<?>)local).isCarrierThreadLocalPresent();
2373 }
2374
2375 public Object[] scopedValueCache() {
2376 return Thread.scopedValueCache();
2377 }
2378
2379 public void setScopedValueCache(Object[] cache) {
2380 Thread.setScopedValueCache(cache);
2381 }
2382
2383 public Object scopedValueBindings() {
2384 return Thread.scopedValueBindings();
2385 }
2386
2387 public Continuation getContinuation(Thread thread) {
2388 return thread.getContinuation();
2389 }
2390
2391 public void setContinuation(Thread thread, Continuation continuation) {
2392 thread.setContinuation(continuation);
2393 }
2394
2395 public ContinuationScope virtualThreadContinuationScope() {
2396 return VirtualThread.continuationScope();
2397 }
2398
2399 public void parkVirtualThread() {
2400 Thread thread = Thread.currentThread();
2401 if (thread instanceof BaseVirtualThread vthread) {
2402 vthread.park();
2403 } else {
2404 throw new WrongThreadException();
2405 }
2406 }
2407
2408 public void parkVirtualThread(long nanos) {
2409 Thread thread = Thread.currentThread();
2410 if (thread instanceof BaseVirtualThread vthread) {
2411 vthread.parkNanos(nanos);
2412 } else {
2413 throw new WrongThreadException();
2414 }
2415 }
2416
2417 public void unparkVirtualThread(Thread thread) {
2418 if (thread instanceof BaseVirtualThread vthread) {
2419 vthread.unpark();
2420 } else {
2421 throw new WrongThreadException();
2422 }
2423 }
2424
2425 public Executor virtualThreadDefaultScheduler() {
2426 return VirtualThread.defaultScheduler();
2427 }
2428
2429 public StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
2430 ContinuationScope contScope,
2431 Continuation continuation) {
2432 return StackWalker.newInstance(options, null, contScope, continuation);
2433 }
2434
2435 public String getLoaderNameID(ClassLoader loader) {
2436 return loader != null ? loader.nameAndId() : "null";
2437 }
2438
2439 @Override
2440 public void copyToSegmentRaw(String string, MemorySegment segment, long offset) {
2441 string.copyToSegmentRaw(segment, offset);
2442 }
2443
2444 @Override
2445 public boolean bytesCompatible(String string, Charset charset) {
2446 return string.bytesCompatible(charset);
2447 }
2448 });
2449 }
2450 }