1 /*
   2  * Copyright (c) 1994, 2023, 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.invoke.StringConcatFactory;
  42 import java.lang.module.ModuleDescriptor;
  43 import java.lang.reflect.Constructor;
  44 import java.lang.reflect.Executable;
  45 import java.lang.reflect.Method;
  46 import java.lang.reflect.Modifier;
  47 import java.net.URI;
  48 import java.net.URL;
  49 import java.nio.channels.Channel;
  50 import java.nio.channels.spi.SelectorProvider;
  51 import java.nio.charset.CharacterCodingException;
  52 import java.nio.charset.Charset;
  53 import java.security.AccessControlContext;
  54 import java.security.AccessController;
  55 import java.security.CodeSource;
  56 import java.security.PrivilegedAction;
  57 import java.security.ProtectionDomain;
  58 import java.util.Collections;
  59 import java.util.List;
  60 import java.util.Map;
  61 import java.util.Objects;
  62 import java.util.Properties;
  63 import java.util.PropertyPermission;
  64 import java.util.ResourceBundle;
  65 import java.util.Set;
  66 import java.util.WeakHashMap;
  67 import java.util.concurrent.Callable;
  68 import java.util.function.Supplier;
  69 import java.util.concurrent.ConcurrentHashMap;
  70 import java.util.stream.Stream;
  71 
  72 import jdk.internal.logger.LoggerFinderLoader.TemporaryLoggerFinder;
  73 import jdk.internal.misc.CarrierThreadLocal;
  74 import jdk.internal.misc.Unsafe;
  75 import jdk.internal.util.StaticProperty;
  76 import jdk.internal.module.ModuleBootstrap;
  77 import jdk.internal.module.ServicesCatalog;
  78 import jdk.internal.reflect.CallerSensitive;
  79 import jdk.internal.reflect.Reflection;
  80 import jdk.internal.access.JavaLangAccess;
  81 import jdk.internal.access.SharedSecrets;
  82 import jdk.internal.javac.PreviewFeature;
  83 import jdk.internal.logger.LoggerFinderLoader;
  84 import jdk.internal.logger.LazyLoggers;
  85 import jdk.internal.logger.LocalizedLoggerWrapper;
  86 import jdk.internal.misc.VM;
  87 import jdk.internal.util.SystemProps;
  88 import jdk.internal.vm.Continuation;
  89 import jdk.internal.vm.ContinuationScope;
  90 import jdk.internal.vm.StackableScope;
  91 import jdk.internal.vm.ThreadContainer;
  92 import jdk.internal.vm.annotation.IntrinsicCandidate;
  93 import jdk.internal.vm.annotation.Stable;
  94 import sun.nio.fs.DefaultFileSystemProvider;
  95 import sun.reflect.annotation.AnnotationType;
  96 import sun.nio.ch.Interruptible;
  97 import sun.nio.cs.UTF_8;
  98 import sun.security.util.SecurityConstants;
  99 
 100 /**
 101  * The {@code System} class contains several useful class fields
 102  * and methods. It cannot be instantiated.
 103  *
 104  * Among the facilities provided by the {@code System} class
 105  * are standard input, standard output, and error output streams;
 106  * access to externally defined properties and environment
 107  * variables; a means of loading files and libraries; and a utility
 108  * method for quickly copying a portion of an array.
 109  *
 110  * @since   1.0
 111  */
 112 public final class System {
 113     /* Register the natives via the static initializer.
 114      *
 115      * The VM will invoke the initPhase1 method to complete the initialization
 116      * of this class separate from <clinit>.
 117      */
 118     private static native void registerNatives();
 119     static {
 120         registerNatives();
 121     }
 122 
 123     /** Don't let anyone instantiate this class */
 124     private System() {
 125     }
 126 
 127     /**
 128      * The "standard" input stream. This stream is already
 129      * open and ready to supply input data. Typically this stream
 130      * corresponds to keyboard input or another input source specified by
 131      * the host environment or user. In case this stream is wrapped
 132      * in a {@link java.io.InputStreamReader}, {@link Console#charset()}
 133      * should be used for the charset, or consider using
 134      * {@link Console#reader()}.
 135      *
 136      * @see Console#charset()
 137      * @see Console#reader()
 138      */
 139     public static final InputStream in = null;
 140 
 141     /**
 142      * The "standard" output stream. This stream is already
 143      * open and ready to accept output data. Typically this stream
 144      * corresponds to display output or another output destination
 145      * specified by the host environment or user. The encoding used
 146      * in the conversion from characters to bytes is equivalent to
 147      * {@link Console#charset()} if the {@code Console} exists,
 148      * <a href="#stdout.encoding">stdout.encoding</a> otherwise.
 149      * <p>
 150      * For simple stand-alone Java applications, a typical way to write
 151      * a line of output data is:
 152      * <blockquote><pre>
 153      *     System.out.println(data)
 154      * </pre></blockquote>
 155      * <p>
 156      * See the {@code println} methods in class {@code PrintStream}.
 157      *
 158      * @see     java.io.PrintStream#println()
 159      * @see     java.io.PrintStream#println(boolean)
 160      * @see     java.io.PrintStream#println(char)
 161      * @see     java.io.PrintStream#println(char[])
 162      * @see     java.io.PrintStream#println(double)
 163      * @see     java.io.PrintStream#println(float)
 164      * @see     java.io.PrintStream#println(int)
 165      * @see     java.io.PrintStream#println(long)
 166      * @see     java.io.PrintStream#println(java.lang.Object)
 167      * @see     java.io.PrintStream#println(java.lang.String)
 168      * @see     Console#charset()
 169      * @see     <a href="#stdout.encoding">stdout.encoding</a>
 170      */
 171     public static final PrintStream out = null;
 172 
 173     /**
 174      * The "standard" error output stream. This stream is already
 175      * open and ready to accept output data.
 176      * <p>
 177      * Typically this stream corresponds to display output or another
 178      * output destination specified by the host environment or user. By
 179      * convention, this output stream is used to display error messages
 180      * or other information that should come to the immediate attention
 181      * of a user even if the principal output stream, the value of the
 182      * variable {@code out}, has been redirected to a file or other
 183      * destination that is typically not continuously monitored.
 184      * The encoding used in the conversion from characters to bytes is
 185      * equivalent to {@link Console#charset()} if the {@code Console}
 186      * exists, <a href="#stderr.encoding">stderr.encoding</a> otherwise.
 187      *
 188      * @see     Console#charset()
 189      * @see     <a href="#stderr.encoding">stderr.encoding</a>
 190      */
 191     public static final PrintStream err = null;
 192 
 193     // Holder for the initial value of `in`, set within `initPhase1()`.
 194     private static InputStream initialIn;
 195 
 196     // indicates if a security manager is possible
 197     private static final int NEVER = 1;
 198     private static final int MAYBE = 2;
 199     private static @Stable int allowSecurityManager;
 200 
 201     // current security manager
 202     @SuppressWarnings("removal")
 203     private static volatile SecurityManager security;   // read by VM
 204 
 205     // `sun.jnu.encoding` if it is not supported. Otherwise null.
 206     // It is initialized in `initPhase1()` before any charset providers
 207     // are initialized.
 208     private static String notSupportedJnuEncoding;
 209 
 210     // return true if a security manager is allowed
 211     private static boolean allowSecurityManager() {
 212         return (allowSecurityManager != NEVER);
 213     }
 214 
 215     /**
 216      * Reassigns the "standard" input stream.
 217      *
 218      * First, if there is a security manager, its {@code checkPermission}
 219      * method is called with a {@code RuntimePermission("setIO")} permission
 220      *  to see if it's ok to reassign the "standard" input stream.
 221      *
 222      * @param in the new standard input stream.
 223      *
 224      * @throws SecurityException
 225      *        if a security manager exists and its
 226      *        {@code checkPermission} method doesn't allow
 227      *        reassigning of the standard input stream.
 228      *
 229      * @see SecurityManager#checkPermission
 230      * @see java.lang.RuntimePermission
 231      *
 232      * @since   1.1
 233      */
 234     public static void setIn(InputStream in) {
 235         checkIO();
 236         setIn0(in);
 237     }
 238 
 239     /**
 240      * Reassigns the "standard" output stream.
 241      *
 242      * First, if there is a security manager, its {@code checkPermission}
 243      * method is called with a {@code RuntimePermission("setIO")} permission
 244      *  to see if it's ok to reassign the "standard" output stream.
 245      *
 246      * @param out the new standard output stream
 247      *
 248      * @throws SecurityException
 249      *        if a security manager exists and its
 250      *        {@code checkPermission} method doesn't allow
 251      *        reassigning of the standard output stream.
 252      *
 253      * @see SecurityManager#checkPermission
 254      * @see java.lang.RuntimePermission
 255      *
 256      * @since   1.1
 257      */
 258     public static void setOut(PrintStream out) {
 259         checkIO();
 260         setOut0(out);
 261     }
 262 
 263     /**
 264      * Reassigns the "standard" error output stream.
 265      *
 266      * First, if there is a security manager, its {@code checkPermission}
 267      * method is called with a {@code RuntimePermission("setIO")} permission
 268      *  to see if it's ok to reassign the "standard" error output stream.
 269      *
 270      * @param err the new standard error output stream.
 271      *
 272      * @throws SecurityException
 273      *        if a security manager exists and its
 274      *        {@code checkPermission} method doesn't allow
 275      *        reassigning of the standard error output stream.
 276      *
 277      * @see SecurityManager#checkPermission
 278      * @see java.lang.RuntimePermission
 279      *
 280      * @since   1.1
 281      */
 282     public static void setErr(PrintStream err) {
 283         checkIO();
 284         setErr0(err);
 285     }
 286 
 287     private static volatile Console cons;
 288 
 289     /**
 290      * Returns the unique {@link java.io.Console Console} object associated
 291      * with the current Java virtual machine, if any.
 292      *
 293      * @return  The system console, if any, otherwise {@code null}.
 294      *
 295      * @since   1.6
 296      */
 297      public static Console console() {
 298          Console c;
 299          if ((c = cons) == null) {
 300              synchronized (System.class) {
 301                  if ((c = cons) == null) {
 302                      cons = c = SharedSecrets.getJavaIOAccess().console();
 303                  }
 304              }
 305          }
 306          return c;
 307      }
 308 
 309     /**
 310      * Returns the channel inherited from the entity that created this
 311      * Java virtual machine.
 312      *
 313      * This method returns the channel obtained by invoking the
 314      * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
 315      * inheritedChannel} method of the system-wide default
 316      * {@link java.nio.channels.spi.SelectorProvider} object.
 317      *
 318      * <p> In addition to the network-oriented channels described in
 319      * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
 320      * inheritedChannel}, this method may return other kinds of
 321      * channels in the future.
 322      *
 323      * @return  The inherited channel, if any, otherwise {@code null}.
 324      *
 325      * @throws  IOException
 326      *          If an I/O error occurs
 327      *
 328      * @throws  SecurityException
 329      *          If a security manager is present and it does not
 330      *          permit access to the channel.
 331      *
 332      * @since 1.5
 333      */
 334     public static Channel inheritedChannel() throws IOException {
 335         return SelectorProvider.provider().inheritedChannel();
 336     }
 337 
 338     private static void checkIO() {
 339         @SuppressWarnings("removal")
 340         SecurityManager sm = getSecurityManager();
 341         if (sm != null) {
 342             sm.checkPermission(new RuntimePermission("setIO"));
 343         }
 344     }
 345 
 346     private static native void setIn0(InputStream in);
 347     private static native void setOut0(PrintStream out);
 348     private static native void setErr0(PrintStream err);
 349 
 350     private static class CallersHolder {
 351         // Remember callers of setSecurityManager() here so that warning
 352         // is only printed once for each different caller
 353         static final Map<Class<?>, Boolean> callers
 354             = Collections.synchronizedMap(new WeakHashMap<>());
 355     }
 356 
 357     // Remember initial System.err. setSecurityManager() warning goes here
 358     private static volatile @Stable PrintStream initialErrStream;
 359 
 360     private static URL codeSource(Class<?> clazz) {
 361         PrivilegedAction<ProtectionDomain> pa = clazz::getProtectionDomain;
 362         @SuppressWarnings("removal")
 363         CodeSource cs = AccessController.doPrivileged(pa).getCodeSource();
 364         return (cs != null) ? cs.getLocation() : null;
 365     }
 366 
 367     /**
 368      * Sets the system-wide security manager.
 369      *
 370      * If there is a security manager already installed, this method first
 371      * calls the security manager's {@code checkPermission} method
 372      * with a {@code RuntimePermission("setSecurityManager")}
 373      * permission to ensure it's ok to replace the existing
 374      * security manager.
 375      * This may result in throwing a {@code SecurityException}.
 376      *
 377      * <p> Otherwise, the argument is established as the current
 378      * security manager. If the argument is {@code null} and no
 379      * security manager has been established, then no action is taken and
 380      * the method simply returns.
 381      *
 382      * @implNote In the JDK implementation, if the Java virtual machine is
 383      * started with the system property {@code java.security.manager} not set or set to
 384      * the special token "{@code disallow}" then the {@code setSecurityManager}
 385      * method cannot be used to set a security manager. See the following
 386      * <a href="SecurityManager.html#set-security-manager">section of the
 387      * {@code SecurityManager} class specification</a> for more details.
 388      *
 389      * @param  sm the security manager or {@code null}
 390      * @throws SecurityException
 391      *         if the security manager has already been set and its {@code
 392      *         checkPermission} method doesn't allow it to be replaced
 393      * @throws UnsupportedOperationException
 394      *         if {@code sm} is non-null and a security manager is not allowed
 395      *         to be set dynamically
 396      * @see #getSecurityManager
 397      * @see SecurityManager#checkPermission
 398      * @see java.lang.RuntimePermission
 399      * @deprecated This method is only useful in conjunction with
 400      *       {@linkplain SecurityManager the Security Manager}, which is
 401      *       deprecated and subject to removal in a future release.
 402      *       Consequently, this method is also deprecated and subject to
 403      *       removal. There is no replacement for the Security Manager or this
 404      *       method.
 405      */
 406     @Deprecated(since="17", forRemoval=true)
 407     @CallerSensitive
 408     public static void setSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
 409         if (allowSecurityManager()) {
 410             var callerClass = Reflection.getCallerClass();
 411             if (CallersHolder.callers.putIfAbsent(callerClass, true) == null) {
 412                 URL url = codeSource(callerClass);
 413                 final String source;
 414                 if (url == null) {
 415                     source = callerClass.getName();
 416                 } else {
 417                     source = callerClass.getName() + " (" + url + ")";
 418                 }
 419                 initialErrStream.printf("""
 420                         WARNING: A terminally deprecated method in java.lang.System has been called
 421                         WARNING: System::setSecurityManager has been called by %s
 422                         WARNING: Please consider reporting this to the maintainers of %s
 423                         WARNING: System::setSecurityManager will be removed in a future release
 424                         """, source, callerClass.getName());
 425             }
 426             implSetSecurityManager(sm);
 427         } else {
 428             // security manager not allowed
 429             if (sm != null) {
 430                 throw new UnsupportedOperationException(
 431                     "The Security Manager is deprecated and will be removed in a future release");
 432             }
 433         }
 434     }
 435 
 436     private static void implSetSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
 437         if (security == null) {
 438             // ensure image reader is initialized
 439             Object.class.getResource("java/lang/ANY");
 440             // ensure the default file system is initialized
 441             DefaultFileSystemProvider.theFileSystem();
 442         }
 443         if (sm != null) {
 444             try {
 445                 // pre-populates the SecurityManager.packageAccess cache
 446                 // to avoid recursive permission checking issues with custom
 447                 // SecurityManager implementations
 448                 sm.checkPackageAccess("java.lang");
 449             } catch (Exception e) {
 450                 // no-op
 451             }
 452         }
 453         setSecurityManager0(sm);
 454     }
 455 
 456     @SuppressWarnings("removal")
 457     private static synchronized
 458     void setSecurityManager0(final SecurityManager s) {
 459         SecurityManager sm = getSecurityManager();
 460         if (sm != null) {
 461             // ask the currently installed security manager if we
 462             // can replace it.
 463             sm.checkPermission(new RuntimePermission("setSecurityManager"));
 464         }
 465 
 466         if ((s != null) && (s.getClass().getClassLoader() != null)) {
 467             // New security manager class is not on bootstrap classpath.
 468             // Force policy to get initialized before we install the new
 469             // security manager, in order to prevent infinite loops when
 470             // trying to initialize the policy (which usually involves
 471             // accessing some security and/or system properties, which in turn
 472             // calls the installed security manager's checkPermission method
 473             // which will loop infinitely if there is a non-system class
 474             // (in this case: the new security manager class) on the stack).
 475             AccessController.doPrivileged(new PrivilegedAction<>() {
 476                 public Object run() {
 477                     s.getClass().getProtectionDomain().implies
 478                         (SecurityConstants.ALL_PERMISSION);
 479                     return null;
 480                 }
 481             });
 482         }
 483 
 484         security = s;
 485     }
 486 
 487     /**
 488      * Gets the system-wide security manager.
 489      *
 490      * @return  if a security manager has already been established for the
 491      *          current application, then that security manager is returned;
 492      *          otherwise, {@code null} is returned.
 493      * @see     #setSecurityManager
 494      * @deprecated This method is only useful in conjunction with
 495      *       {@linkplain SecurityManager the Security Manager}, which is
 496      *       deprecated and subject to removal in a future release.
 497      *       Consequently, this method is also deprecated and subject to
 498      *       removal. There is no replacement for the Security Manager or this
 499      *       method.
 500      */
 501     @SuppressWarnings("removal")
 502     @Deprecated(since="17", forRemoval=true)
 503     public static SecurityManager getSecurityManager() {
 504         if (allowSecurityManager()) {
 505             return security;
 506         } else {
 507             return null;
 508         }
 509     }
 510 
 511     /**
 512      * Returns the current time in milliseconds.  Note that
 513      * while the unit of time of the return value is a millisecond,
 514      * the granularity of the value depends on the underlying
 515      * operating system and may be larger.  For example, many
 516      * operating systems measure time in units of tens of
 517      * milliseconds.
 518      *
 519      * <p> See the description of the class {@code Date} for
 520      * a discussion of slight discrepancies that may arise between
 521      * "computer time" and coordinated universal time (UTC).
 522      *
 523      * @return  the difference, measured in milliseconds, between
 524      *          the current time and midnight, January 1, 1970 UTC.
 525      * @see     java.util.Date
 526      */
 527     @IntrinsicCandidate
 528     public static native long currentTimeMillis();
 529 
 530     /**
 531      * Returns the current value of the running Java Virtual Machine's
 532      * high-resolution time source, in nanoseconds.
 533      *
 534      * This method can only be used to measure elapsed time and is
 535      * not related to any other notion of system or wall-clock time.
 536      * The value returned represents nanoseconds since some fixed but
 537      * arbitrary <i>origin</i> time (perhaps in the future, so values
 538      * may be negative).  The same origin is used by all invocations of
 539      * this method in an instance of a Java virtual machine; other
 540      * virtual machine instances are likely to use a different origin.
 541      *
 542      * <p>This method provides nanosecond precision, but not necessarily
 543      * nanosecond resolution (that is, how frequently the value changes)
 544      * - no guarantees are made except that the resolution is at least as
 545      * good as that of {@link #currentTimeMillis()}.
 546      *
 547      * <p>Differences in successive calls that span greater than
 548      * approximately 292 years (2<sup>63</sup> nanoseconds) will not
 549      * correctly compute elapsed time due to numerical overflow.
 550      *
 551      * <p>The values returned by this method become meaningful only when
 552      * the difference between two such values, obtained within the same
 553      * instance of a Java virtual machine, is computed.
 554      *
 555      * <p>For example, to measure how long some code takes to execute:
 556      * <pre> {@code
 557      * long startTime = System.nanoTime();
 558      * // ... the code being measured ...
 559      * long elapsedNanos = System.nanoTime() - startTime;}</pre>
 560      *
 561      * <p>To compare elapsed time against a timeout, use <pre> {@code
 562      * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
 563      * instead of <pre> {@code
 564      * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
 565      * because of the possibility of numerical overflow.
 566      *
 567      * @return the current value of the running Java Virtual Machine's
 568      *         high-resolution time source, in nanoseconds
 569      * @since 1.5
 570      */
 571     @IntrinsicCandidate
 572     public static native long nanoTime();
 573 
 574     /**
 575      * Copies an array from the specified source array, beginning at the
 576      * specified position, to the specified position of the destination array.
 577      * A subsequence of array components are copied from the source
 578      * array referenced by {@code src} to the destination array
 579      * referenced by {@code dest}. The number of components copied is
 580      * equal to the {@code length} argument. The components at
 581      * positions {@code srcPos} through
 582      * {@code srcPos+length-1} in the source array are copied into
 583      * positions {@code destPos} through
 584      * {@code destPos+length-1}, respectively, of the destination
 585      * array.
 586      * <p>
 587      * If the {@code src} and {@code dest} arguments refer to the
 588      * same array object, then the copying is performed as if the
 589      * components at positions {@code srcPos} through
 590      * {@code srcPos+length-1} were first copied to a temporary
 591      * array with {@code length} components and then the contents of
 592      * the temporary array were copied into positions
 593      * {@code destPos} through {@code destPos+length-1} of the
 594      * destination array.
 595      * <p>
 596      * If {@code dest} is {@code null}, then a
 597      * {@code NullPointerException} is thrown.
 598      * <p>
 599      * If {@code src} is {@code null}, then a
 600      * {@code NullPointerException} is thrown and the destination
 601      * array is not modified.
 602      * <p>
 603      * Otherwise, if any of the following is true, an
 604      * {@code ArrayStoreException} is thrown and the destination is
 605      * not modified:
 606      * <ul>
 607      * <li>The {@code src} argument refers to an object that is not an
 608      *     array.
 609      * <li>The {@code dest} argument refers to an object that is not an
 610      *     array.
 611      * <li>The {@code src} argument and {@code dest} argument refer
 612      *     to arrays whose component types are different primitive types.
 613      * <li>The {@code src} argument refers to an array with a primitive
 614      *    component type and the {@code dest} argument refers to an array
 615      *     with a reference component type.
 616      * <li>The {@code src} argument refers to an array with a reference
 617      *    component type and the {@code dest} argument refers to an array
 618      *     with a primitive component type.
 619      * </ul>
 620      * <p>
 621      * Otherwise, if any of the following is true, an
 622      * {@code IndexOutOfBoundsException} is
 623      * thrown and the destination is not modified:
 624      * <ul>
 625      * <li>The {@code srcPos} argument is negative.
 626      * <li>The {@code destPos} argument is negative.
 627      * <li>The {@code length} argument is negative.
 628      * <li>{@code srcPos+length} is greater than
 629      *     {@code src.length}, the length of the source array.
 630      * <li>{@code destPos+length} is greater than
 631      *     {@code dest.length}, the length of the destination array.
 632      * </ul>
 633      * <p>
 634      * Otherwise, if any actual component of the source array from
 635      * position {@code srcPos} through
 636      * {@code srcPos+length-1} cannot be converted to the component
 637      * type of the destination array by assignment conversion, an
 638      * {@code ArrayStoreException} is thrown. In this case, let
 639      * <b><i>k</i></b> be the smallest nonnegative integer less than
 640      * length such that {@code src[srcPos+}<i>k</i>{@code ]}
 641      * cannot be converted to the component type of the destination
 642      * array; when the exception is thrown, source array components from
 643      * positions {@code srcPos} through
 644      * {@code srcPos+}<i>k</i>{@code -1}
 645      * will already have been copied to destination array positions
 646      * {@code destPos} through
 647      * {@code destPos+}<i>k</I>{@code -1} and no other
 648      * positions of the destination array will have been modified.
 649      * (Because of the restrictions already itemized, this
 650      * paragraph effectively applies only to the situation where both
 651      * arrays have component types that are reference types.)
 652      *
 653      * @param      src      the source array.
 654      * @param      srcPos   starting position in the source array.
 655      * @param      dest     the destination array.
 656      * @param      destPos  starting position in the destination data.
 657      * @param      length   the number of array elements to be copied.
 658      * @throws     IndexOutOfBoundsException  if copying would cause
 659      *             access of data outside array bounds.
 660      * @throws     ArrayStoreException  if an element in the {@code src}
 661      *             array could not be stored into the {@code dest} array
 662      *             because of a type mismatch.
 663      * @throws     NullPointerException if either {@code src} or
 664      *             {@code dest} is {@code null}.
 665      */
 666     @IntrinsicCandidate
 667     public static native void arraycopy(Object src,  int  srcPos,
 668                                         Object dest, int destPos,
 669                                         int length);
 670 
 671     /**
 672      * Returns the same hash code for the given object as
 673      * would be returned by the default method hashCode(),
 674      * whether or not the given object's class overrides
 675      * hashCode().
 676      * The hash code for the null reference is zero.
 677      *
 678      * @param x object for which the hashCode is to be calculated
 679      * @return  the hashCode
 680      * @since   1.1
 681      * @see Object#hashCode
 682      * @see java.util.Objects#hashCode(Object)
 683      */
 684     @IntrinsicCandidate
 685     public static native int identityHashCode(Object x);
 686 
 687     /**
 688      * System properties.
 689      *
 690      * See {@linkplain #getProperties getProperties} for details.
 691      */
 692     private static Properties props;
 693 
 694     /**
 695      * Determines the current system properties.
 696      *
 697      * First, if there is a security manager, its
 698      * {@code checkPropertiesAccess} method is called with no
 699      * arguments. This may result in a security exception.
 700      * <p>
 701      * The current set of system properties for use by the
 702      * {@link #getProperty(String)} method is returned as a
 703      * {@code Properties} object. If there is no current set of
 704      * system properties, a set of system properties is first created and
 705      * initialized. This set of system properties includes a value
 706      * for each of the following keys unless the description of the associated
 707      * value indicates that the value is optional.
 708      * <table class="striped" style="text-align:left">
 709      * <caption style="display:none">Shows property keys and associated values</caption>
 710      * <thead>
 711      * <tr><th scope="col">Key</th>
 712      *     <th scope="col">Description of Associated Value</th></tr>
 713      * </thead>
 714      * <tbody>
 715      * <tr><th scope="row">{@systemProperty java.version}</th>
 716      *     <td>Java Runtime Environment version, which may be interpreted
 717      *     as a {@link Runtime.Version}</td></tr>
 718      * <tr><th scope="row">{@systemProperty java.version.date}</th>
 719      *     <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
 720      *     format, which may be interpreted as a {@link
 721      *     java.time.LocalDate}</td></tr>
 722      * <tr><th scope="row">{@systemProperty java.vendor}</th>
 723      *     <td>Java Runtime Environment vendor</td></tr>
 724      * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
 725      *     <td>Java vendor URL</td></tr>
 726      * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
 727      *     <td>Java vendor version <em>(optional)</em> </td></tr>
 728      * <tr><th scope="row">{@systemProperty java.home}</th>
 729      *     <td>Java installation directory</td></tr>
 730      * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
 731      *     <td>Java Virtual Machine specification version, whose value is the
 732      *     {@linkplain Runtime.Version#feature feature} element of the
 733      *     {@linkplain Runtime#version() runtime version}</td></tr>
 734      * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
 735      *     <td>Java Virtual Machine specification vendor</td></tr>
 736      * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
 737      *     <td>Java Virtual Machine specification name</td></tr>
 738      * <tr><th scope="row">{@systemProperty java.vm.version}</th>
 739      *     <td>Java Virtual Machine implementation version which may be
 740      *     interpreted as a {@link Runtime.Version}</td></tr>
 741      * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
 742      *     <td>Java Virtual Machine implementation vendor</td></tr>
 743      * <tr><th scope="row">{@systemProperty java.vm.name}</th>
 744      *     <td>Java Virtual Machine implementation name</td></tr>
 745      * <tr><th scope="row">{@systemProperty java.specification.version}</th>
 746      *     <td>Java Runtime Environment specification version, whose value is
 747      *     the {@linkplain Runtime.Version#feature feature} element of the
 748      *     {@linkplain Runtime#version() runtime version}</td></tr>
 749      * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
 750      *     <td>Java Runtime Environment specification maintenance version,
 751      *     may be interpreted as a positive integer <em>(optional, see below)</em></td></tr>
 752      * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
 753      *     <td>Java Runtime Environment specification  vendor</td></tr>
 754      * <tr><th scope="row">{@systemProperty java.specification.name}</th>
 755      *     <td>Java Runtime Environment specification  name</td></tr>
 756      * <tr><th scope="row">{@systemProperty java.class.version}</th>
 757      *     <td>{@linkplain java.lang.reflect.ClassFileFormatVersion#latest() Latest}
 758      *     Java class file format version recognized by the Java runtime as {@code "MAJOR.MINOR"}
 759      *     where {@link java.lang.reflect.ClassFileFormatVersion#major() MAJOR} and {@code MINOR}
 760      *     are both formatted as decimal integers</td></tr>
 761      * <tr><th scope="row">{@systemProperty java.class.path}</th>
 762      *     <td>Java class path  (refer to
 763      *        {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
 764      * <tr><th scope="row">{@systemProperty java.library.path}</th>
 765      *     <td>List of paths to search when loading libraries</td></tr>
 766      * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
 767      *     <td>Default temp file path</td></tr>
 768      * <tr><th scope="row">{@systemProperty os.name}</th>
 769      *     <td>Operating system name</td></tr>
 770      * <tr><th scope="row">{@systemProperty os.arch}</th>
 771      *     <td>Operating system architecture</td></tr>
 772      * <tr><th scope="row">{@systemProperty os.version}</th>
 773      *     <td>Operating system version</td></tr>
 774      * <tr><th scope="row">{@systemProperty file.separator}</th>
 775      *     <td>File separator ("/" on UNIX)</td></tr>
 776      * <tr><th scope="row">{@systemProperty path.separator}</th>
 777      *     <td>Path separator (":" on UNIX)</td></tr>
 778      * <tr><th scope="row">{@systemProperty line.separator}</th>
 779      *     <td>Line separator ("\n" on UNIX)</td></tr>
 780      * <tr><th scope="row">{@systemProperty user.name}</th>
 781      *     <td>User's account name</td></tr>
 782      * <tr><th scope="row">{@systemProperty user.home}</th>
 783      *     <td>User's home directory</td></tr>
 784      * <tr><th scope="row">{@systemProperty user.dir}</th>
 785      *     <td>User's current working directory</td></tr>
 786      * <tr><th scope="row">{@systemProperty native.encoding}</th>
 787      *     <td>Character encoding name derived from the host environment and/or
 788      *     the user's settings. Setting this system property has no effect.</td></tr>
 789      * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
 790      *     <td>Character encoding name for {@link System#out System.out}.
 791      *     The Java runtime can be started with the system property set to {@code UTF-8},
 792      *     starting it with the property set to another value leads to undefined behavior.
 793      * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
 794      *     <td>Character encoding name for {@link System#err System.err}.
 795      *     The Java runtime can be started with the system property set to {@code UTF-8},
 796      *     starting it with the property set to another value leads to undefined behavior.
 797      * </tbody>
 798      * </table>
 799      * <p>
 800      * The {@code java.specification.maintenance.version} property is
 801      * defined if the specification implemented by this runtime at the
 802      * time of its construction had undergone a <a
 803      * href="https://jcp.org/en/procedures/jcp2#3.6.4">maintenance
 804      * release</a>. When defined, its value identifies that
 805      * maintenance release. To indicate the first maintenance release
 806      * this property will have the value {@code "1"}, to indicate the
 807      * second maintenance release this property will have the value
 808      * {@code "2"}, and so on.
 809      * <p>
 810      * Multiple paths in a system property value are separated by the path
 811      * separator character of the platform.
 812      * <p>
 813      * Note that even if the security manager does not permit the
 814      * {@code getProperties} operation, it may choose to permit the
 815      * {@link #getProperty(String)} operation.
 816      *
 817      * @apiNote
 818      * <strong>Changing a standard system property may have unpredictable results
 819      * unless otherwise specified.</strong>
 820      * Property values may be cached during initialization or on first use.
 821      * Setting a standard property after initialization using {@link #getProperties()},
 822      * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
 823      * {@link #clearProperty(String)} may not have the desired effect.
 824      *
 825      * @implNote
 826      * In addition to the standard system properties, the system
 827      * properties may include the following keys:
 828      * <table class="striped">
 829      * <caption style="display:none">Shows property keys and associated values</caption>
 830      * <thead>
 831      * <tr><th scope="col">Key</th>
 832      *     <th scope="col">Description of Associated Value</th></tr>
 833      * </thead>
 834      * <tbody>
 835      * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
 836      *     <td>The application module path</td></tr>
 837      * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
 838      *     <td>The upgrade module path</td></tr>
 839      * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
 840      *     <td>The module name of the initial/main module</td></tr>
 841      * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
 842      *     <td>The main class name of the initial module</td></tr>
 843      * <tr><th scope="row">{@systemProperty file.encoding}</th>
 844      *     <td>The name of the default charset, defaults to {@code UTF-8}.
 845      *     The property may be set on the command line to the value
 846      *     {@code UTF-8} or {@code COMPAT}. If set on the command line to
 847      *     the value {@code COMPAT} then the value is replaced with the
 848      *     value of the {@code native.encoding} property during startup.
 849      *     Setting the property to a value other than {@code UTF-8} or
 850      *     {@code COMPAT} leads to unspecified behavior.
 851      *     </td></tr>
 852      * </tbody>
 853      * </table>
 854      *
 855      * @return     the system properties
 856      * @throws     SecurityException  if a security manager exists and its
 857      *             {@code checkPropertiesAccess} method doesn't allow access
 858      *             to the system properties.
 859      * @see        #setProperties
 860      * @see        java.lang.SecurityException
 861      * @see        java.lang.SecurityManager#checkPropertiesAccess()
 862      * @see        java.util.Properties
 863      */
 864     public static Properties getProperties() {
 865         @SuppressWarnings("removal")
 866         SecurityManager sm = getSecurityManager();
 867         if (sm != null) {
 868             sm.checkPropertiesAccess();
 869         }
 870 
 871         return props;
 872     }
 873 
 874     /**
 875      * Returns the system-dependent line separator string.  It always
 876      * returns the same value - the initial value of the {@linkplain
 877      * #getProperty(String) system property} {@code line.separator}.
 878      *
 879      * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
 880      * Windows systems it returns {@code "\r\n"}.
 881      *
 882      * @return the system-dependent line separator string
 883      * @since 1.7
 884      */
 885     public static String lineSeparator() {
 886         return lineSeparator;
 887     }
 888 
 889     private static String lineSeparator;
 890 
 891     /**
 892      * Sets the system properties to the {@code Properties} argument.
 893      *
 894      * First, if there is a security manager, its
 895      * {@code checkPropertiesAccess} method is called with no
 896      * arguments. This may result in a security exception.
 897      * <p>
 898      * The argument becomes the current set of system properties for use
 899      * by the {@link #getProperty(String)} method. If the argument is
 900      * {@code null}, then the current set of system properties is
 901      * forgotten.
 902      *
 903      * @apiNote
 904      * <strong>Changing a standard system property may have unpredictable results
 905      * unless otherwise specified</strong>.
 906      * See {@linkplain #getProperties getProperties} for details.
 907      *
 908      * @param      props   the new system properties.
 909      * @throws     SecurityException  if a security manager exists and its
 910      *             {@code checkPropertiesAccess} method doesn't allow access
 911      *             to the system properties.
 912      * @see        #getProperties
 913      * @see        java.util.Properties
 914      * @see        java.lang.SecurityException
 915      * @see        java.lang.SecurityManager#checkPropertiesAccess()
 916      */
 917     public static void setProperties(Properties props) {
 918         @SuppressWarnings("removal")
 919         SecurityManager sm = getSecurityManager();
 920         if (sm != null) {
 921             sm.checkPropertiesAccess();
 922         }
 923 
 924         if (props == null) {
 925             Map<String, String> tempProps = SystemProps.initProperties();
 926             VersionProps.init(tempProps);
 927             props = createProperties(tempProps);
 928         }
 929         System.props = props;
 930     }
 931 
 932     /**
 933      * Gets the system property indicated by the specified key.
 934      *
 935      * First, if there is a security manager, its
 936      * {@code checkPropertyAccess} method is called with the key as
 937      * its argument. This may result in a SecurityException.
 938      * <p>
 939      * If there is no current set of system properties, a set of system
 940      * properties is first created and initialized in the same manner as
 941      * for the {@code getProperties} method.
 942      *
 943      * @apiNote
 944      * <strong>Changing a standard system property may have unpredictable results
 945      * unless otherwise specified</strong>.
 946      * See {@linkplain #getProperties getProperties} for details.
 947      *
 948      * @param      key   the name of the system property.
 949      * @return     the string value of the system property,
 950      *             or {@code null} if there is no property with that key.
 951      *
 952      * @throws     SecurityException  if a security manager exists and its
 953      *             {@code checkPropertyAccess} method doesn't allow
 954      *             access to the specified system property.
 955      * @throws     NullPointerException if {@code key} is {@code null}.
 956      * @throws     IllegalArgumentException if {@code key} is empty.
 957      * @see        #setProperty
 958      * @see        java.lang.SecurityException
 959      * @see        java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
 960      * @see        java.lang.System#getProperties()
 961      */
 962     public static String getProperty(String key) {
 963         checkKey(key);
 964         @SuppressWarnings("removal")
 965         SecurityManager sm = getSecurityManager();
 966         if (sm != null) {
 967             sm.checkPropertyAccess(key);
 968         }
 969 
 970         return props.getProperty(key);
 971     }
 972 
 973     /**
 974      * Gets the system property indicated by the specified key.
 975      *
 976      * First, if there is a security manager, its
 977      * {@code checkPropertyAccess} method is called with the
 978      * {@code key} as its argument.
 979      * <p>
 980      * If there is no current set of system properties, a set of system
 981      * properties is first created and initialized in the same manner as
 982      * for the {@code getProperties} method.
 983      *
 984      * @param      key   the name of the system property.
 985      * @param      def   a default value.
 986      * @return     the string value of the system property,
 987      *             or the default value if there is no property with that key.
 988      *
 989      * @throws     SecurityException  if a security manager exists and its
 990      *             {@code checkPropertyAccess} method doesn't allow
 991      *             access to the specified system property.
 992      * @throws     NullPointerException if {@code key} is {@code null}.
 993      * @throws     IllegalArgumentException if {@code key} is empty.
 994      * @see        #setProperty
 995      * @see        java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
 996      * @see        java.lang.System#getProperties()
 997      */
 998     public static String getProperty(String key, String def) {
 999         checkKey(key);
1000         @SuppressWarnings("removal")
1001         SecurityManager sm = getSecurityManager();
1002         if (sm != null) {
1003             sm.checkPropertyAccess(key);
1004         }
1005 
1006         return props.getProperty(key, def);
1007     }
1008 
1009     /**
1010      * Sets the system property indicated by the specified key.
1011      *
1012      * First, if a security manager exists, its
1013      * {@code SecurityManager.checkPermission} method
1014      * is called with a {@code PropertyPermission(key, "write")}
1015      * permission. This may result in a SecurityException being thrown.
1016      * If no exception is thrown, the specified property is set to the given
1017      * value.
1018      *
1019      * @apiNote
1020      * <strong>Changing a standard system property may have unpredictable results
1021      * unless otherwise specified</strong>.
1022      * See {@linkplain #getProperties getProperties} for details.
1023      *
1024      * @param      key   the name of the system property.
1025      * @param      value the value of the system property.
1026      * @return     the previous value of the system property,
1027      *             or {@code null} if it did not have one.
1028      *
1029      * @throws     SecurityException  if a security manager exists and its
1030      *             {@code checkPermission} method doesn't allow
1031      *             setting of the specified property.
1032      * @throws     NullPointerException if {@code key} or
1033      *             {@code value} is {@code null}.
1034      * @throws     IllegalArgumentException if {@code key} is empty.
1035      * @see        #getProperty
1036      * @see        java.lang.System#getProperty(java.lang.String)
1037      * @see        java.lang.System#getProperty(java.lang.String, java.lang.String)
1038      * @see        java.util.PropertyPermission
1039      * @see        SecurityManager#checkPermission
1040      * @since      1.2
1041      */
1042     public static String setProperty(String key, String value) {
1043         checkKey(key);
1044         @SuppressWarnings("removal")
1045         SecurityManager sm = getSecurityManager();
1046         if (sm != null) {
1047             sm.checkPermission(new PropertyPermission(key,
1048                 SecurityConstants.PROPERTY_WRITE_ACTION));
1049         }
1050 
1051         return (String) props.setProperty(key, value);
1052     }
1053 
1054     /**
1055      * Removes the system property indicated by the specified key.
1056      *
1057      * First, if a security manager exists, its
1058      * {@code SecurityManager.checkPermission} method
1059      * is called with a {@code PropertyPermission(key, "write")}
1060      * permission. This may result in a SecurityException being thrown.
1061      * If no exception is thrown, the specified property is removed.
1062      *
1063      * @apiNote
1064      * <strong>Changing a standard system property may have unpredictable results
1065      * unless otherwise specified</strong>.
1066      * See {@linkplain #getProperties getProperties} method for details.
1067      *
1068      * @param      key   the name of the system property to be removed.
1069      * @return     the previous string value of the system property,
1070      *             or {@code null} if there was no property with that key.
1071      *
1072      * @throws     SecurityException  if a security manager exists and its
1073      *             {@code checkPropertyAccess} method doesn't allow
1074      *              access to the specified system property.
1075      * @throws     NullPointerException if {@code key} is {@code null}.
1076      * @throws     IllegalArgumentException if {@code key} is empty.
1077      * @see        #getProperty
1078      * @see        #setProperty
1079      * @see        java.util.Properties
1080      * @see        java.lang.SecurityException
1081      * @see        java.lang.SecurityManager#checkPropertiesAccess()
1082      * @since 1.5
1083      */
1084     public static String clearProperty(String key) {
1085         checkKey(key);
1086         @SuppressWarnings("removal")
1087         SecurityManager sm = getSecurityManager();
1088         if (sm != null) {
1089             sm.checkPermission(new PropertyPermission(key, "write"));
1090         }
1091 
1092         return (String) props.remove(key);
1093     }
1094 
1095     private static void checkKey(String key) {
1096         if (key == null) {
1097             throw new NullPointerException("key can't be null");
1098         }
1099         if (key.isEmpty()) {
1100             throw new IllegalArgumentException("key can't be empty");
1101         }
1102     }
1103 
1104     /**
1105      * Gets the value of the specified environment variable. An
1106      * environment variable is a system-dependent external named
1107      * value.
1108      *
1109      * <p>If a security manager exists, its
1110      * {@link SecurityManager#checkPermission checkPermission}
1111      * method is called with a
1112      * {@link RuntimePermission RuntimePermission("getenv."+name)}
1113      * permission.  This may result in a {@link SecurityException}
1114      * being thrown.  If no exception is thrown the value of the
1115      * variable {@code name} is returned.
1116      *
1117      * <p><a id="EnvironmentVSSystemProperties"><i>System
1118      * properties</i> and <i>environment variables</i></a> are both
1119      * conceptually mappings between names and values.  Both
1120      * mechanisms can be used to pass user-defined information to a
1121      * Java process.  Environment variables have a more global effect,
1122      * because they are visible to all descendants of the process
1123      * which defines them, not just the immediate Java subprocess.
1124      * They can have subtly different semantics, such as case
1125      * insensitivity, on different operating systems.  For these
1126      * reasons, environment variables are more likely to have
1127      * unintended side effects.  It is best to use system properties
1128      * where possible.  Environment variables should be used when a
1129      * global effect is desired, or when an external system interface
1130      * requires an environment variable (such as {@code PATH}).
1131      *
1132      * <p>On UNIX systems the alphabetic case of {@code name} is
1133      * typically significant, while on Microsoft Windows systems it is
1134      * typically not.  For example, the expression
1135      * {@code System.getenv("FOO").equals(System.getenv("foo"))}
1136      * is likely to be true on Microsoft Windows.
1137      *
1138      * @param  name the name of the environment variable
1139      * @return the string value of the variable, or {@code null}
1140      *         if the variable is not defined in the system environment
1141      * @throws NullPointerException if {@code name} is {@code null}
1142      * @throws SecurityException
1143      *         if a security manager exists and its
1144      *         {@link SecurityManager#checkPermission checkPermission}
1145      *         method doesn't allow access to the environment variable
1146      *         {@code name}
1147      * @see    #getenv()
1148      * @see    ProcessBuilder#environment()
1149      */
1150     public static String getenv(String name) {
1151         @SuppressWarnings("removal")
1152         SecurityManager sm = getSecurityManager();
1153         if (sm != null) {
1154             sm.checkPermission(new RuntimePermission("getenv."+name));
1155         }
1156 
1157         return ProcessEnvironment.getenv(name);
1158     }
1159 
1160 
1161     /**
1162      * Returns an unmodifiable string map view of the current system environment.
1163      * The environment is a system-dependent mapping from names to
1164      * values which is passed from parent to child processes.
1165      *
1166      * <p>If the system does not support environment variables, an
1167      * empty map is returned.
1168      *
1169      * <p>The returned map will never contain null keys or values.
1170      * Attempting to query the presence of a null key or value will
1171      * throw a {@link NullPointerException}.  Attempting to query
1172      * the presence of a key or value which is not of type
1173      * {@link String} will throw a {@link ClassCastException}.
1174      *
1175      * <p>The returned map and its collection views may not obey the
1176      * general contract of the {@link Object#equals} and
1177      * {@link Object#hashCode} methods.
1178      *
1179      * <p>The returned map is typically case-sensitive on all platforms.
1180      *
1181      * <p>If a security manager exists, its
1182      * {@link SecurityManager#checkPermission checkPermission}
1183      * method is called with a
1184      * {@link RuntimePermission RuntimePermission("getenv.*")} permission.
1185      * This may result in a {@link SecurityException} being thrown.
1186      *
1187      * <p>When passing information to a Java subprocess,
1188      * <a href=#EnvironmentVSSystemProperties>system properties</a>
1189      * are generally preferred over environment variables.
1190      *
1191      * @return the environment as a map of variable names to values
1192      * @throws SecurityException
1193      *         if a security manager exists and its
1194      *         {@link SecurityManager#checkPermission checkPermission}
1195      *         method doesn't allow access to the process environment
1196      * @see    #getenv(String)
1197      * @see    ProcessBuilder#environment()
1198      * @since  1.5
1199      */
1200     public static java.util.Map<String,String> getenv() {
1201         @SuppressWarnings("removal")
1202         SecurityManager sm = getSecurityManager();
1203         if (sm != null) {
1204             sm.checkPermission(new RuntimePermission("getenv.*"));
1205         }
1206 
1207         return ProcessEnvironment.getenv();
1208     }
1209 
1210     /**
1211      * {@code System.Logger} instances log messages that will be
1212      * routed to the underlying logging framework the {@link System.LoggerFinder
1213      * LoggerFinder} uses.
1214      *
1215      * {@code System.Logger} instances are typically obtained from
1216      * the {@link java.lang.System System} class, by calling
1217      * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
1218      * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
1219      * System.getLogger(loggerName, bundle)}.
1220      *
1221      * @see java.lang.System#getLogger(java.lang.String)
1222      * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
1223      * @see java.lang.System.LoggerFinder
1224      *
1225      * @since 9
1226      */
1227     public interface Logger {
1228 
1229         /**
1230          * System {@linkplain Logger loggers} levels.
1231          *
1232          * A level has a {@linkplain #getName() name} and {@linkplain
1233          * #getSeverity() severity}.
1234          * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
1235          * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
1236          * by order of increasing severity.
1237          * <br>
1238          * {@link #ALL} and {@link #OFF}
1239          * are simple markers with severities mapped respectively to
1240          * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
1241          * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
1242          * <p>
1243          * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
1244          * <p>
1245          * {@linkplain System.Logger.Level System logger levels} are mapped to
1246          * {@linkplain java.logging/java.util.logging.Level  java.util.logging levels}
1247          * of corresponding severity.
1248          * <br>The mapping is as follows:
1249          * <br><br>
1250          * <table class="striped">
1251          * <caption>System.Logger Severity Level Mapping</caption>
1252          * <thead>
1253          * <tr><th scope="col">System.Logger Levels</th>
1254          *     <th scope="col">java.util.logging Levels</th>
1255          * </thead>
1256          * <tbody>
1257          * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
1258          *     <td>{@link java.logging/java.util.logging.Level#ALL ALL}</td>
1259          * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
1260          *     <td>{@link java.logging/java.util.logging.Level#FINER FINER}</td>
1261          * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
1262          *     <td>{@link java.logging/java.util.logging.Level#FINE FINE}</td>
1263          * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
1264          *     <td>{@link java.logging/java.util.logging.Level#INFO INFO}</td>
1265          * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
1266          *     <td>{@link java.logging/java.util.logging.Level#WARNING WARNING}</td>
1267          * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
1268          *     <td>{@link java.logging/java.util.logging.Level#SEVERE SEVERE}</td>
1269          * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
1270          *     <td>{@link java.logging/java.util.logging.Level#OFF OFF}</td>
1271          * </tbody>
1272          * </table>
1273          *
1274          * @since 9
1275          *
1276          * @see java.lang.System.LoggerFinder
1277          * @see java.lang.System.Logger
1278          */
1279         @SuppressWarnings("doclint:reference") // cross-module links
1280         public enum Level {
1281 
1282             // for convenience, we're reusing java.util.logging.Level int values
1283             // the mapping logic in sun.util.logging.PlatformLogger depends
1284             // on this.
1285             /**
1286              * A marker to indicate that all levels are enabled.
1287              * This level {@linkplain #getSeverity() severity} is
1288              * {@link Integer#MIN_VALUE}.
1289              */
1290             ALL(Integer.MIN_VALUE),  // typically mapped to/from j.u.l.Level.ALL
1291             /**
1292              * {@code TRACE} level: usually used to log diagnostic information.
1293              * This level {@linkplain #getSeverity() severity} is
1294              * {@code 400}.
1295              */
1296             TRACE(400),   // typically mapped to/from j.u.l.Level.FINER
1297             /**
1298              * {@code DEBUG} level: usually used to log debug information traces.
1299              * This level {@linkplain #getSeverity() severity} is
1300              * {@code 500}.
1301              */
1302             DEBUG(500),   // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
1303             /**
1304              * {@code INFO} level: usually used to log information messages.
1305              * This level {@linkplain #getSeverity() severity} is
1306              * {@code 800}.
1307              */
1308             INFO(800),    // typically mapped to/from j.u.l.Level.INFO
1309             /**
1310              * {@code WARNING} level: usually used to log warning messages.
1311              * This level {@linkplain #getSeverity() severity} is
1312              * {@code 900}.
1313              */
1314             WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
1315             /**
1316              * {@code ERROR} level: usually used to log error messages.
1317              * This level {@linkplain #getSeverity() severity} is
1318              * {@code 1000}.
1319              */
1320             ERROR(1000),  // typically mapped to/from j.u.l.Level.SEVERE
1321             /**
1322              * A marker to indicate that all levels are disabled.
1323              * This level {@linkplain #getSeverity() severity} is
1324              * {@link Integer#MAX_VALUE}.
1325              */
1326             OFF(Integer.MAX_VALUE);  // typically mapped to/from j.u.l.Level.OFF
1327 
1328             private final int severity;
1329 
1330             private Level(int severity) {
1331                 this.severity = severity;
1332             }
1333 
1334             /**
1335              * Returns the name of this level.
1336              * @return this level {@linkplain #name()}.
1337              */
1338             public final String getName() {
1339                 return name();
1340             }
1341 
1342             /**
1343              * Returns the severity of this level.
1344              * A higher severity means a more severe condition.
1345              * @return this level severity.
1346              */
1347             public final int getSeverity() {
1348                 return severity;
1349             }
1350         }
1351 
1352         /**
1353          * Returns the name of this logger.
1354          *
1355          * @return the logger name.
1356          */
1357         public String getName();
1358 
1359         /**
1360          * Checks if a message of the given level would be logged by
1361          * this logger.
1362          *
1363          * @param level the log message level.
1364          * @return {@code true} if the given log message level is currently
1365          *         being logged.
1366          *
1367          * @throws NullPointerException if {@code level} is {@code null}.
1368          */
1369         public boolean isLoggable(Level level);
1370 
1371         /**
1372          * Logs a message.
1373          *
1374          * @implSpec The default implementation for this method calls
1375          * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1376          *
1377          * @param level the log message level.
1378          * @param msg the string message (or a key in the message catalog, if
1379          * this logger is a {@link
1380          * LoggerFinder#getLocalizedLogger(java.lang.String,
1381          * java.util.ResourceBundle, java.lang.Module) localized logger});
1382          * can be {@code null}.
1383          *
1384          * @throws NullPointerException if {@code level} is {@code null}.
1385          */
1386         public default void log(Level level, String msg) {
1387             log(level, (ResourceBundle) null, msg, (Object[]) null);
1388         }
1389 
1390         /**
1391          * Logs a lazily supplied message.
1392          *
1393          * If the logger is currently enabled for the given log message level
1394          * then a message is logged that is the result produced by the
1395          * given supplier function.  Otherwise, the supplier is not operated on.
1396          *
1397          * @implSpec When logging is enabled for the given level, the default
1398          * implementation for this method calls
1399          * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
1400          *
1401          * @param level the log message level.
1402          * @param msgSupplier a supplier function that produces a message.
1403          *
1404          * @throws NullPointerException if {@code level} is {@code null},
1405          *         or {@code msgSupplier} is {@code null}.
1406          */
1407         public default void log(Level level, Supplier<String> msgSupplier) {
1408             Objects.requireNonNull(msgSupplier);
1409             if (isLoggable(Objects.requireNonNull(level))) {
1410                 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1411             }
1412         }
1413 
1414         /**
1415          * Logs a message produced from the given object.
1416          *
1417          * If the logger is currently enabled for the given log message level then
1418          * a message is logged that, by default, is the result produced from
1419          * calling  toString on the given object.
1420          * Otherwise, the object is not operated on.
1421          *
1422          * @implSpec When logging is enabled for the given level, the default
1423          * implementation for this method calls
1424          * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1425          *
1426          * @param level the log message level.
1427          * @param obj the object to log.
1428          *
1429          * @throws NullPointerException if {@code level} is {@code null}, or
1430          *         {@code obj} is {@code null}.
1431          */
1432         public default void log(Level level, Object obj) {
1433             Objects.requireNonNull(obj);
1434             if (isLoggable(Objects.requireNonNull(level))) {
1435                 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1436             }
1437         }
1438 
1439         /**
1440          * Logs a message associated with a given throwable.
1441          *
1442          * @implSpec The default implementation for this method calls
1443          * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1444          *
1445          * @param level the log message level.
1446          * @param msg the string message (or a key in the message catalog, if
1447          * this logger is a {@link
1448          * LoggerFinder#getLocalizedLogger(java.lang.String,
1449          * java.util.ResourceBundle, java.lang.Module) localized logger});
1450          * can be {@code null}.
1451          * @param thrown a {@code Throwable} associated with the log message;
1452          *        can be {@code null}.
1453          *
1454          * @throws NullPointerException if {@code level} is {@code null}.
1455          */
1456         public default void log(Level level, String msg, Throwable thrown) {
1457             this.log(level, null, msg, thrown);
1458         }
1459 
1460         /**
1461          * Logs a lazily supplied message associated with a given throwable.
1462          *
1463          * If the logger is currently enabled for the given log message level
1464          * then a message is logged that is the result produced by the
1465          * given supplier function.  Otherwise, the supplier is not operated on.
1466          *
1467          * @implSpec When logging is enabled for the given level, the default
1468          * implementation for this method calls
1469          * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1470          *
1471          * @param level one of the log message level identifiers.
1472          * @param msgSupplier a supplier function that produces a message.
1473          * @param thrown a {@code Throwable} associated with log message;
1474          *               can be {@code null}.
1475          *
1476          * @throws NullPointerException if {@code level} is {@code null}, or
1477          *                               {@code msgSupplier} is {@code null}.
1478          */
1479         public default void log(Level level, Supplier<String> msgSupplier,
1480                 Throwable thrown) {
1481             Objects.requireNonNull(msgSupplier);
1482             if (isLoggable(Objects.requireNonNull(level))) {
1483                 this.log(level, null, msgSupplier.get(), thrown);
1484             }
1485         }
1486 
1487         /**
1488          * Logs a message with an optional list of parameters.
1489          *
1490          * @implSpec The default implementation for this method calls
1491          * {@code this.log(level, (ResourceBundle)null, format, params);}
1492          *
1493          * @param level one of the log message level identifiers.
1494          * @param format the string message format in {@link
1495          * java.text.MessageFormat} format, (or a key in the message
1496          * catalog, if this logger is a {@link
1497          * LoggerFinder#getLocalizedLogger(java.lang.String,
1498          * java.util.ResourceBundle, java.lang.Module) localized logger});
1499          * can be {@code null}.
1500          * @param params an optional list of parameters to the message (may be
1501          * none).
1502          *
1503          * @throws NullPointerException if {@code level} is {@code null}.
1504          */
1505         public default void log(Level level, String format, Object... params) {
1506             this.log(level, null, format, params);
1507         }
1508 
1509         /**
1510          * Logs a localized message associated with a given throwable.
1511          *
1512          * If the given resource bundle is non-{@code null},  the {@code msg}
1513          * string is localized using the given resource bundle.
1514          * Otherwise the {@code msg} string is not localized.
1515          *
1516          * @param level the log message level.
1517          * @param bundle a resource bundle to localize {@code msg}; can be
1518          * {@code null}.
1519          * @param msg the string message (or a key in the message catalog,
1520          *            if {@code bundle} is not {@code null}); can be {@code null}.
1521          * @param thrown a {@code Throwable} associated with the log message;
1522          *        can be {@code null}.
1523          *
1524          * @throws NullPointerException if {@code level} is {@code null}.
1525          */
1526         public void log(Level level, ResourceBundle bundle, String msg,
1527                 Throwable thrown);
1528 
1529         /**
1530          * Logs a message with resource bundle and an optional list of
1531          * parameters.
1532          *
1533          * If the given resource bundle is non-{@code null},  the {@code format}
1534          * string is localized using the given resource bundle.
1535          * Otherwise the {@code format} string is not localized.
1536          *
1537          * @param level the log message level.
1538          * @param bundle a resource bundle to localize {@code format}; can be
1539          * {@code null}.
1540          * @param format the string message format in {@link
1541          * java.text.MessageFormat} format, (or a key in the message
1542          * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1543          * @param params an optional list of parameters to the message (may be
1544          * none).
1545          *
1546          * @throws NullPointerException if {@code level} is {@code null}.
1547          */
1548         public void log(Level level, ResourceBundle bundle, String format,
1549                 Object... params);
1550     }
1551 
1552     /**
1553      * The {@code LoggerFinder} service is responsible for creating, managing,
1554      * and configuring loggers to the underlying framework it uses.
1555      *
1556      * A logger finder is a concrete implementation of this class that has a
1557      * zero-argument constructor and implements the abstract methods defined
1558      * by this class.
1559      * The loggers returned from a logger finder are capable of routing log
1560      * messages to the logging backend this provider supports.
1561      * A given invocation of the Java Runtime maintains a single
1562      * system-wide LoggerFinder instance that is loaded as follows:
1563      * <ul>
1564      *    <li>First it finds any custom {@code LoggerFinder} provider
1565      *        using the {@link java.util.ServiceLoader} facility with the
1566      *        {@linkplain ClassLoader#getSystemClassLoader() system class
1567      *        loader}.</li>
1568      *    <li>If no {@code LoggerFinder} provider is found, the system default
1569      *        {@code LoggerFinder} implementation will be used.</li>
1570      * </ul>
1571      * <p>
1572      * An application can replace the logging backend
1573      * <i>even when the java.logging module is present</i>, by simply providing
1574      * and declaring an implementation of the {@link LoggerFinder} service.
1575      * <p>
1576      * <b>Default Implementation</b>
1577      * <p>
1578      * The system default {@code LoggerFinder} implementation uses
1579      * {@code java.util.logging} as the backend framework when the
1580      * {@code java.logging} module is present.
1581      * It returns a {@linkplain System.Logger logger} instance
1582      * that will route log messages to a {@link java.logging/java.util.logging.Logger
1583      * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1584      * present, the default implementation will return a simple logger
1585      * instance that will route log messages of {@code INFO} level and above to
1586      * the console ({@code System.err}).
1587      * <p>
1588      * <b>Logging Configuration</b>
1589      * <p>
1590      * {@linkplain Logger Logger} instances obtained from the
1591      * {@code LoggerFinder} factory methods are not directly configurable by
1592      * the application. Configuration is the responsibility of the underlying
1593      * logging backend, and usually requires using APIs specific to that backend.
1594      * <p>For the default {@code LoggerFinder} implementation
1595      * using {@code java.util.logging} as its backend, refer to
1596      * {@link java.logging/java.util.logging java.util.logging} for logging configuration.
1597      * For the default {@code LoggerFinder} implementation returning simple loggers
1598      * when the {@code java.logging} module is absent, the configuration
1599      * is implementation dependent.
1600      * <p>
1601      * Usually an application that uses a logging framework will log messages
1602      * through a logger facade defined (or supported) by that framework.
1603      * Applications that wish to use an external framework should log
1604      * through the facade associated with that framework.
1605      * <p>
1606      * A system class that needs to log messages will typically obtain
1607      * a {@link System.Logger} instance to route messages to the logging
1608      * framework selected by the application.
1609      * <p>
1610      * Libraries and classes that only need loggers to produce log messages
1611      * should not attempt to configure loggers by themselves, as that
1612      * would make them dependent from a specific implementation of the
1613      * {@code LoggerFinder} service.
1614      * <p>
1615      * In addition, when a security manager is present, loggers provided to
1616      * system classes should not be directly configurable through the logging
1617      * backend without requiring permissions.
1618      * <br>
1619      * It is the responsibility of the provider of
1620      * the concrete {@code LoggerFinder} implementation to ensure that
1621      * these loggers are not configured by untrusted code without proper
1622      * permission checks, as configuration performed on such loggers usually
1623      * affects all applications in the same Java Runtime.
1624      * <p>
1625      * <b>Message Levels and Mapping to backend levels</b>
1626      * <p>
1627      * A logger finder is responsible for mapping from a {@code
1628      * System.Logger.Level} to a level supported by the logging backend it uses.
1629      * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1630      * maps {@code System.Logger} levels to
1631      * {@linkplain java.logging/java.util.logging.Level java.util.logging} levels
1632      * of corresponding severity - as described in {@link Logger.Level
1633      * Logger.Level}.
1634      *
1635      * @see java.lang.System
1636      * @see java.lang.System.Logger
1637      *
1638      * @since 9
1639      */
1640     @SuppressWarnings("doclint:reference") // cross-module links
1641     public abstract static class LoggerFinder {
1642         /**
1643          * The {@code RuntimePermission("loggerFinder")} is
1644          * necessary to subclass and instantiate the {@code LoggerFinder} class,
1645          * as well as to obtain loggers from an instance of that class.
1646          */
1647         static final RuntimePermission LOGGERFINDER_PERMISSION =
1648                 new RuntimePermission("loggerFinder");
1649 
1650         /**
1651          * Creates a new instance of {@code LoggerFinder}.
1652          *
1653          * @implNote It is recommended that a {@code LoggerFinder} service
1654          *   implementation does not perform any heavy initialization in its
1655          *   constructor, in order to avoid possible risks of deadlock or class
1656          *   loading cycles during the instantiation of the service provider.
1657          *
1658          * @throws SecurityException if a security manager is present and its
1659          *         {@code checkPermission} method doesn't allow the
1660          *         {@code RuntimePermission("loggerFinder")}.
1661          */
1662         protected LoggerFinder() {
1663             this(checkPermission());
1664         }
1665 
1666         private LoggerFinder(Void unused) {
1667             // nothing to do.
1668         }
1669 
1670         private static Void checkPermission() {
1671             @SuppressWarnings("removal")
1672             final SecurityManager sm = System.getSecurityManager();
1673             if (sm != null) {
1674                 sm.checkPermission(LOGGERFINDER_PERMISSION);
1675             }
1676             return null;
1677         }
1678 
1679         /**
1680          * Returns an instance of {@link Logger Logger}
1681          * for the given {@code module}.
1682          *
1683          * @param name the name of the logger.
1684          * @param module the module for which the logger is being requested.
1685          *
1686          * @return a {@link Logger logger} suitable for use within the given
1687          *         module.
1688          * @throws NullPointerException if {@code name} is {@code null} or
1689          *        {@code module} is {@code null}.
1690          * @throws SecurityException if a security manager is present and its
1691          *         {@code checkPermission} method doesn't allow the
1692          *         {@code RuntimePermission("loggerFinder")}.
1693          */
1694         public abstract Logger getLogger(String name, Module module);
1695 
1696         /**
1697          * Returns a localizable instance of {@link Logger Logger}
1698          * for the given {@code module}.
1699          * The returned logger will use the provided resource bundle for
1700          * message localization.
1701          *
1702          * @implSpec By default, this method calls {@link
1703          * #getLogger(java.lang.String, java.lang.Module)
1704          * this.getLogger(name, module)} to obtain a logger, then wraps that
1705          * logger in a {@link Logger} instance where all methods that do not
1706          * take a {@link ResourceBundle} as parameter are redirected to one
1707          * which does - passing the given {@code bundle} for
1708          * localization. So for instance, a call to {@link
1709          * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1710          * will end up as a call to {@link
1711          * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1712          * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1713          * logger instance.
1714          * Note however that by default, string messages returned by {@link
1715          * java.util.function.Supplier Supplier&lt;String&gt;} will not be
1716          * localized, as it is assumed that such strings are messages which are
1717          * already constructed, rather than keys in a resource bundle.
1718          * <p>
1719          * An implementation of {@code LoggerFinder} may override this method,
1720          * for example, when the underlying logging backend provides its own
1721          * mechanism for localizing log messages, then such a
1722          * {@code LoggerFinder} would be free to return a logger
1723          * that makes direct use of the mechanism provided by the backend.
1724          *
1725          * @param name    the name of the logger.
1726          * @param bundle  a resource bundle; can be {@code null}.
1727          * @param module  the module for which the logger is being requested.
1728          * @return an instance of {@link Logger Logger}  which will use the
1729          * provided resource bundle for message localization.
1730          *
1731          * @throws NullPointerException if {@code name} is {@code null} or
1732          *         {@code module} is {@code null}.
1733          * @throws SecurityException if a security manager is present and its
1734          *         {@code checkPermission} method doesn't allow the
1735          *         {@code RuntimePermission("loggerFinder")}.
1736          */
1737         public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1738                                          Module module) {
1739             return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1740         }
1741 
1742         /**
1743          * Returns the {@code LoggerFinder} instance. There is one
1744          * single system-wide {@code LoggerFinder} instance in
1745          * the Java Runtime.  See the class specification of how the
1746          * {@link LoggerFinder LoggerFinder} implementation is located and
1747          * loaded.
1748          *
1749          * @return the {@link LoggerFinder LoggerFinder} instance.
1750          * @throws SecurityException if a security manager is present and its
1751          *         {@code checkPermission} method doesn't allow the
1752          *         {@code RuntimePermission("loggerFinder")}.
1753          */
1754         public static LoggerFinder getLoggerFinder() {
1755             @SuppressWarnings("removal")
1756             final SecurityManager sm = System.getSecurityManager();
1757             if (sm != null) {
1758                 sm.checkPermission(LOGGERFINDER_PERMISSION);
1759             }
1760             return accessProvider();
1761         }
1762 
1763 
1764         private static volatile LoggerFinder service;
1765         @SuppressWarnings("removal")
1766         static LoggerFinder accessProvider() {
1767             // We do not need to synchronize: LoggerFinderLoader will
1768             // always return the same instance, so if we don't have it,
1769             // just fetch it again.
1770             LoggerFinder finder = service;
1771             if (finder == null) {
1772                 PrivilegedAction<LoggerFinder> pa =
1773                         () -> LoggerFinderLoader.getLoggerFinder();
1774                 finder = AccessController.doPrivileged(pa, null,
1775                         LOGGERFINDER_PERMISSION);
1776                 if (finder instanceof TemporaryLoggerFinder) return finder;
1777                 service = finder;
1778             }
1779             return finder;
1780         }
1781 
1782     }
1783 
1784 
1785     /**
1786      * Returns an instance of {@link Logger Logger} for the caller's
1787      * use.
1788      *
1789      * @implSpec
1790      * Instances returned by this method route messages to loggers
1791      * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1792      * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1793      * {@code module} is the caller's module.
1794      * In cases where {@code System.getLogger} is called from a context where
1795      * there is no caller frame on the stack (e.g when called directly
1796      * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1797      * To obtain a logger in such a context, use an auxiliary class that will
1798      * implicitly be identified as the caller, or use the system {@link
1799      * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1800      * Note that doing the latter may eagerly initialize the underlying
1801      * logging system.
1802      *
1803      * @apiNote
1804      * This method may defer calling the {@link
1805      * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1806      * LoggerFinder.getLogger} method to create an actual logger supplied by
1807      * the logging backend, for instance, to allow loggers to be obtained during
1808      * the system initialization time.
1809      *
1810      * @param name the name of the logger.
1811      * @return an instance of {@link Logger} that can be used by the calling
1812      *         class.
1813      * @throws NullPointerException if {@code name} is {@code null}.
1814      * @throws IllegalCallerException if there is no Java caller frame on the
1815      *         stack.
1816      *
1817      * @since 9
1818      */
1819     @CallerSensitive
1820     public static Logger getLogger(String name) {
1821         Objects.requireNonNull(name);
1822         final Class<?> caller = Reflection.getCallerClass();
1823         if (caller == null) {
1824             throw new IllegalCallerException("no caller frame");
1825         }
1826         return LazyLoggers.getLogger(name, caller.getModule());
1827     }
1828 
1829     /**
1830      * Returns a localizable instance of {@link Logger
1831      * Logger} for the caller's use.
1832      * The returned logger will use the provided resource bundle for message
1833      * localization.
1834      *
1835      * @implSpec
1836      * The returned logger will perform message localization as specified
1837      * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1838      * java.util.ResourceBundle, java.lang.Module)
1839      * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1840      * {@code module} is the caller's module.
1841      * In cases where {@code System.getLogger} is called from a context where
1842      * there is no caller frame on the stack (e.g when called directly
1843      * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1844      * To obtain a logger in such a context, use an auxiliary class that
1845      * will implicitly be identified as the caller, or use the system {@link
1846      * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1847      * Note that doing the latter may eagerly initialize the underlying
1848      * logging system.
1849      *
1850      * @apiNote
1851      * This method is intended to be used after the system is fully initialized.
1852      * This method may trigger the immediate loading and initialization
1853      * of the {@link LoggerFinder} service, which may cause issues if the
1854      * Java Runtime is not ready to initialize the concrete service
1855      * implementation yet.
1856      * System classes which may be loaded early in the boot sequence and
1857      * need to log localized messages should create a logger using
1858      * {@link #getLogger(java.lang.String)} and then use the log methods that
1859      * take a resource bundle as parameter.
1860      *
1861      * @param name    the name of the logger.
1862      * @param bundle  a resource bundle.
1863      * @return an instance of {@link Logger} which will use the provided
1864      * resource bundle for message localization.
1865      * @throws NullPointerException if {@code name} is {@code null} or
1866      *         {@code bundle} is {@code null}.
1867      * @throws IllegalCallerException if there is no Java caller frame on the
1868      *         stack.
1869      *
1870      * @since 9
1871      */
1872     @SuppressWarnings("removal")
1873     @CallerSensitive
1874     public static Logger getLogger(String name, ResourceBundle bundle) {
1875         final ResourceBundle rb = Objects.requireNonNull(bundle);
1876         Objects.requireNonNull(name);
1877         final Class<?> caller = Reflection.getCallerClass();
1878         if (caller == null) {
1879             throw new IllegalCallerException("no caller frame");
1880         }
1881         final SecurityManager sm = System.getSecurityManager();
1882         // We don't use LazyLoggers if a resource bundle is specified.
1883         // Bootstrap sensitive classes in the JDK do not use resource bundles
1884         // when logging. This could be revisited later, if it needs to.
1885         if (sm != null) {
1886             final PrivilegedAction<Logger> pa =
1887                     () -> LoggerFinder.accessProvider()
1888                             .getLocalizedLogger(name, rb, caller.getModule());
1889             return AccessController.doPrivileged(pa, null,
1890                                          LoggerFinder.LOGGERFINDER_PERMISSION);
1891         }
1892         return LoggerFinder.accessProvider()
1893                 .getLocalizedLogger(name, rb, caller.getModule());
1894     }
1895 
1896     /**
1897      * Initiates the {@linkplain Runtime##shutdown shutdown sequence} of the Java Virtual Machine.
1898      * Unless the security manager denies exiting, this method initiates the shutdown sequence
1899      * (if it is not already initiated) and then blocks indefinitely. This method neither returns
1900      * nor throws an exception; that is, it does not complete either normally or abruptly.
1901      * <p>
1902      * The argument serves as a status code. By convention, a nonzero status code
1903      * indicates abnormal termination.
1904      * <p>
1905      * The call {@code System.exit(n)} is effectively equivalent to the call:
1906      * {@snippet :
1907      *     Runtime.getRuntime().exit(n)
1908      * }
1909      *
1910      * @implNote
1911      * The initiation of the shutdown sequence is logged by {@link Runtime#exit(int)}.
1912      *
1913      * @param  status exit status.
1914      * @throws SecurityException
1915      *         if a security manager exists and its {@code checkExit} method
1916      *         doesn't allow exit with the specified status.
1917      * @see    java.lang.Runtime#exit(int)
1918      */
1919     public static void exit(int status) {
1920         Runtime.getRuntime().exit(status);
1921     }
1922 
1923     /**
1924      * Runs the garbage collector in the Java Virtual Machine.
1925      * <p>
1926      * Calling the {@code gc} method suggests that the Java Virtual Machine
1927      * expend effort toward recycling unused objects in order to
1928      * make the memory they currently occupy available for reuse
1929      * by the Java Virtual Machine.
1930      * When control returns from the method call, the Java Virtual Machine
1931      * has made a best effort to reclaim space from all unused objects.
1932      * There is no guarantee that this effort will recycle any particular
1933      * number of unused objects, reclaim any particular amount of space, or
1934      * complete at any particular time, if at all, before the method returns or ever.
1935      * There is also no guarantee that this effort will determine
1936      * the change of reachability in any particular number of objects,
1937      * or that any particular number of {@link java.lang.ref.Reference Reference}
1938      * objects will be cleared and enqueued.
1939      *
1940      * <p>
1941      * The call {@code System.gc()} is effectively equivalent to the
1942      * call:
1943      * <blockquote><pre>
1944      * Runtime.getRuntime().gc()
1945      * </pre></blockquote>
1946      *
1947      * @see     java.lang.Runtime#gc()
1948      */
1949     public static void gc() {
1950         Runtime.getRuntime().gc();
1951     }
1952 
1953     /**
1954      * Runs the finalization methods of any objects pending finalization.
1955      *
1956      * Calling this method suggests that the Java Virtual Machine expend
1957      * effort toward running the {@code finalize} methods of objects
1958      * that have been found to be discarded but whose {@code finalize}
1959      * methods have not yet been run. When control returns from the
1960      * method call, the Java Virtual Machine has made a best effort to
1961      * complete all outstanding finalizations.
1962      * <p>
1963      * The call {@code System.runFinalization()} is effectively
1964      * equivalent to the call:
1965      * <blockquote><pre>
1966      * Runtime.getRuntime().runFinalization()
1967      * </pre></blockquote>
1968      *
1969      * @deprecated Finalization has been deprecated for removal.  See
1970      * {@link java.lang.Object#finalize} for background information and details
1971      * about migration options.
1972      * <p>
1973      * When running in a JVM in which finalization has been disabled or removed,
1974      * no objects will be pending finalization, so this method does nothing.
1975      *
1976      * @see     java.lang.Runtime#runFinalization()
1977      * @jls 12.6 Finalization of Class Instances
1978      */
1979     @Deprecated(since="18", forRemoval=true)
1980     @SuppressWarnings("removal")
1981     public static void runFinalization() {
1982         Runtime.getRuntime().runFinalization();
1983     }
1984 
1985     /**
1986      * Loads the native library specified by the filename argument.  The filename
1987      * argument must be an absolute path name.
1988      *
1989      * If the filename argument, when stripped of any platform-specific library
1990      * prefix, path, and file extension, indicates a library whose name is,
1991      * for example, L, and a native library called L is statically linked
1992      * with the VM, then the JNI_OnLoad_L function exported by the library
1993      * is invoked rather than attempting to load a dynamic library.
1994      * A filename matching the argument does not have to exist in the
1995      * file system.
1996      * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1997      * for more details.
1998      *
1999      * Otherwise, the filename argument is mapped to a native library image in
2000      * an implementation-dependent manner.
2001      *
2002      * <p>
2003      * The call {@code System.load(name)} is effectively equivalent
2004      * to the call:
2005      * <blockquote><pre>
2006      * Runtime.getRuntime().load(name)
2007      * </pre></blockquote>
2008      *
2009      * @param      filename   the file to load.
2010      * @throws     SecurityException  if a security manager exists and its
2011      *             {@code checkLink} method doesn't allow
2012      *             loading of the specified dynamic library
2013      * @throws     UnsatisfiedLinkError  if either the filename is not an
2014      *             absolute path name, the native library is not statically
2015      *             linked with the VM, or the library cannot be mapped to
2016      *             a native library image by the host system.
2017      * @throws     NullPointerException if {@code filename} is {@code null}
2018      *
2019      * @spec jni/index.html Java Native Interface Specification
2020      * @see        java.lang.Runtime#load(java.lang.String)
2021      * @see        java.lang.SecurityManager#checkLink(java.lang.String)
2022      */
2023     @CallerSensitive
2024     public static void load(String filename) {
2025         Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
2026     }
2027 
2028     /**
2029      * Loads the native library specified by the {@code libname}
2030      * argument.  The {@code libname} argument must not contain any platform
2031      * specific prefix, file extension or path. If a native library
2032      * called {@code libname} is statically linked with the VM, then the
2033      * JNI_OnLoad_{@code libname} function exported by the library is invoked.
2034      * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
2035      * for more details.
2036      *
2037      * Otherwise, the libname argument is loaded from a system library
2038      * location and mapped to a native library image in an
2039      * implementation-dependent manner.
2040      * <p>
2041      * The call {@code System.loadLibrary(name)} is effectively
2042      * equivalent to the call
2043      * <blockquote><pre>
2044      * Runtime.getRuntime().loadLibrary(name)
2045      * </pre></blockquote>
2046      *
2047      * @param      libname   the name of the library.
2048      * @throws     SecurityException  if a security manager exists and its
2049      *             {@code checkLink} method doesn't allow
2050      *             loading of the specified dynamic library
2051      * @throws     UnsatisfiedLinkError if either the libname argument
2052      *             contains a file path, the native library is not statically
2053      *             linked with the VM,  or the library cannot be mapped to a
2054      *             native library image by the host system.
2055      * @throws     NullPointerException if {@code libname} is {@code null}
2056      *
2057      * @spec jni/index.html Java Native Interface Specification
2058      * @see        java.lang.Runtime#loadLibrary(java.lang.String)
2059      * @see        java.lang.SecurityManager#checkLink(java.lang.String)
2060      */
2061     @CallerSensitive
2062     public static void loadLibrary(String libname) {
2063         Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
2064     }
2065 
2066     /**
2067      * Maps a library name into a platform-specific string representing
2068      * a native library.
2069      *
2070      * @param      libname the name of the library.
2071      * @return     a platform-dependent native library name.
2072      * @throws     NullPointerException if {@code libname} is {@code null}
2073      * @see        java.lang.System#loadLibrary(java.lang.String)
2074      * @see        java.lang.ClassLoader#findLibrary(java.lang.String)
2075      * @since      1.2
2076      */
2077     public static native String mapLibraryName(String libname);
2078 
2079     /**
2080      * Create PrintStream for stdout/err based on encoding.
2081      */
2082     private static PrintStream newPrintStream(OutputStream out, String enc) {
2083         if (enc != null) {
2084             return new PrintStream(new BufferedOutputStream(out, 128), true,
2085                                    Charset.forName(enc, UTF_8.INSTANCE));
2086         }
2087         return new PrintStream(new BufferedOutputStream(out, 128), true);
2088     }
2089 
2090     /**
2091      * Logs an exception/error at initialization time to stdout or stderr.
2092      *
2093      * @param printToStderr to print to stderr rather than stdout
2094      * @param printStackTrace to print the stack trace
2095      * @param msg the message to print before the exception, can be {@code null}
2096      * @param e the exception or error
2097      */
2098     private static void logInitException(boolean printToStderr,
2099                                          boolean printStackTrace,
2100                                          String msg,
2101                                          Throwable e) {
2102         if (VM.initLevel() < 1) {
2103             throw new InternalError("system classes not initialized");
2104         }
2105         PrintStream log = (printToStderr) ? err : out;
2106         if (msg != null) {
2107             log.println(msg);
2108         }
2109         if (printStackTrace) {
2110             e.printStackTrace(log);
2111         } else {
2112             log.println(e);
2113             for (Throwable suppressed : e.getSuppressed()) {
2114                 log.println("Suppressed: " + suppressed);
2115             }
2116             Throwable cause = e.getCause();
2117             if (cause != null) {
2118                 log.println("Caused by: " + cause);
2119             }
2120         }
2121     }
2122 
2123     /**
2124      * Create the Properties object from a map - masking out system properties
2125      * that are not intended for public access.
2126      */
2127     private static Properties createProperties(Map<String, String> initialProps) {
2128         Properties properties = new Properties(initialProps.size());
2129         for (var entry : initialProps.entrySet()) {
2130             String prop = entry.getKey();
2131             switch (prop) {
2132                 // Do not add private system properties to the Properties
2133                 case "sun.nio.MaxDirectMemorySize":
2134                 case "sun.nio.PageAlignDirectMemory":
2135                     // used by java.lang.Integer.IntegerCache
2136                 case "java.lang.Integer.IntegerCache.high":
2137                     // used by sun.launcher.LauncherHelper
2138                 case "sun.java.launcher.diag":
2139                     // used by jdk.internal.loader.ClassLoaders
2140                 case "jdk.boot.class.path.append":
2141                     break;
2142                 default:
2143                     properties.put(prop, entry.getValue());
2144             }
2145         }
2146         return properties;
2147     }
2148 
2149     /**
2150      * Initialize the system class.  Called after thread initialization.
2151      */
2152     private static void initPhase1() {
2153 
2154         // register the shared secrets - do this first, since SystemProps.initProperties
2155         // might initialize CharsetDecoders that rely on it
2156         setJavaLangAccess();
2157 
2158         // VM might invoke JNU_NewStringPlatform() to set those encoding
2159         // sensitive properties (user.home, user.name, boot.class.path, etc.)
2160         // during "props" initialization.
2161         // The charset is initialized in System.c and does not depend on the Properties.
2162         Map<String, String> tempProps = SystemProps.initProperties();
2163         VersionProps.init(tempProps);
2164 
2165         // There are certain system configurations that may be controlled by
2166         // VM options such as the maximum amount of direct memory and
2167         // Integer cache size used to support the object identity semantics
2168         // of autoboxing.  Typically, the library will obtain these values
2169         // from the properties set by the VM.  If the properties are for
2170         // internal implementation use only, these properties should be
2171         // masked from the system properties.
2172         //
2173         // Save a private copy of the system properties object that
2174         // can only be accessed by the internal implementation.
2175         VM.saveProperties(tempProps);
2176         props = createProperties(tempProps);
2177 
2178         // Check if sun.jnu.encoding is supported. If not, replace it with UTF-8.
2179         var jnuEncoding = props.getProperty("sun.jnu.encoding");
2180         if (jnuEncoding == null || !Charset.isSupported(jnuEncoding)) {
2181             notSupportedJnuEncoding = jnuEncoding == null ? "null" : jnuEncoding;
2182             props.setProperty("sun.jnu.encoding", "UTF-8");
2183         }
2184 
2185         StaticProperty.javaHome();          // Load StaticProperty to cache the property values
2186 
2187         lineSeparator = props.getProperty("line.separator");
2188 
2189         FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
2190         FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
2191         FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
2192         initialIn = new BufferedInputStream(fdIn);
2193         setIn0(initialIn);
2194         // stdout/err.encoding are set when the VM is associated with the terminal,
2195         // thus they are equivalent to Console.charset(), otherwise the encodings
2196         // of those properties default to native.encoding
2197         setOut0(newPrintStream(fdOut, props.getProperty("stdout.encoding")));
2198         setErr0(newPrintStream(fdErr, props.getProperty("stderr.encoding")));
2199 
2200         // Setup Java signal handlers for HUP, TERM, and INT (where available).
2201         Terminator.setup();
2202 
2203         // Initialize any miscellaneous operating system settings that need to be
2204         // set for the class libraries. Currently this is no-op everywhere except
2205         // for Windows where the process-wide error mode is set before the java.io
2206         // classes are used.
2207         VM.initializeOSEnvironment();
2208 
2209         // start Finalizer and Reference Handler threads
2210         SharedSecrets.getJavaLangRefAccess().startThreads();
2211 
2212         // system properties, java.lang and other core classes are now initialized
2213         VM.initLevel(1);
2214     }
2215 
2216     // @see #initPhase2()
2217     static ModuleLayer bootLayer;
2218 
2219     /*
2220      * Invoked by VM.  Phase 2 module system initialization.
2221      * Only classes in java.base can be loaded in this phase.
2222      *
2223      * @param printToStderr print exceptions to stderr rather than stdout
2224      * @param printStackTrace print stack trace when exception occurs
2225      *
2226      * @return JNI_OK for success, JNI_ERR for failure
2227      */
2228     private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
2229 
2230         try {
2231             bootLayer = ModuleBootstrap.boot();
2232         } catch (Exception | Error e) {
2233             logInitException(printToStderr, printStackTrace,
2234                              "Error occurred during initialization of boot layer", e);
2235             return -1; // JNI_ERR
2236         }
2237 
2238         // module system initialized
2239         VM.initLevel(2);
2240 
2241         return 0; // JNI_OK
2242     }
2243 
2244     /*
2245      * Invoked by VM.  Phase 3 is the final system initialization:
2246      * 1. eagerly initialize bootstrap method factories that might interact
2247      *    negatively with custom security managers and custom class loaders
2248      * 2. set security manager
2249      * 3. set system class loader
2250      * 4. set TCCL
2251      *
2252      * This method must be called after the module system initialization.
2253      * The security manager and system class loader may be a custom class from
2254      * the application classpath or modulepath.
2255      */
2256     @SuppressWarnings("removal")
2257     private static void initPhase3() {
2258 
2259         // Initialize the StringConcatFactory eagerly to avoid potential
2260         // bootstrap circularity issues that could be caused by a custom
2261         // SecurityManager
2262         Unsafe.getUnsafe().ensureClassInitialized(StringConcatFactory.class);
2263 
2264         // Emit a warning if java.io.tmpdir is set via the command line
2265         // to a directory that doesn't exist
2266         if (SystemProps.isBadIoTmpdir()) {
2267             System.err.println("WARNING: java.io.tmpdir directory does not exist");
2268         }
2269 
2270         String smProp = System.getProperty("java.security.manager");
2271         boolean needWarning = false;
2272         if (smProp != null) {
2273             switch (smProp) {
2274                 case "disallow":
2275                     allowSecurityManager = NEVER;
2276                     break;
2277                 case "allow":
2278                     allowSecurityManager = MAYBE;
2279                     break;
2280                 case "":
2281                 case "default":
2282                     implSetSecurityManager(new SecurityManager());
2283                     allowSecurityManager = MAYBE;
2284                     needWarning = true;
2285                     break;
2286                 default:
2287                     try {
2288                         ClassLoader cl = ClassLoader.getBuiltinAppClassLoader();
2289                         Class<?> c = Class.forName(smProp, false, cl);
2290                         Constructor<?> ctor = c.getConstructor();
2291                         // Must be a public subclass of SecurityManager with
2292                         // a public no-arg constructor
2293                         if (!SecurityManager.class.isAssignableFrom(c) ||
2294                             !Modifier.isPublic(c.getModifiers()) ||
2295                             !Modifier.isPublic(ctor.getModifiers())) {
2296                             throw new Error("Could not create SecurityManager: "
2297                                              + ctor.toString());
2298                         }
2299                         // custom security manager may be in non-exported package
2300                         ctor.setAccessible(true);
2301                         SecurityManager sm = (SecurityManager) ctor.newInstance();
2302                         implSetSecurityManager(sm);
2303                         needWarning = true;
2304                     } catch (Exception e) {
2305                         throw new InternalError("Could not create SecurityManager", e);
2306                     }
2307                     allowSecurityManager = MAYBE;
2308             }
2309         } else {
2310             allowSecurityManager = NEVER;
2311         }
2312 
2313         if (needWarning) {
2314             System.err.println("""
2315                     WARNING: A command line option has enabled the Security Manager
2316                     WARNING: The Security Manager is deprecated and will be removed in a future release""");
2317         }
2318 
2319         // Emit a warning if `sun.jnu.encoding` is not supported.
2320         if (notSupportedJnuEncoding != null) {
2321             System.err.println(
2322                     "WARNING: The encoding of the underlying platform's" +
2323                     " file system is not supported: " +
2324                     notSupportedJnuEncoding);
2325         }
2326 
2327         initialErrStream = System.err;
2328 
2329         // initializing the system class loader
2330         VM.initLevel(3);
2331 
2332         // system class loader initialized
2333         ClassLoader scl = ClassLoader.initSystemClassLoader();
2334 
2335         // set TCCL
2336         Thread.currentThread().setContextClassLoader(scl);
2337 
2338         // system is fully initialized
2339         VM.initLevel(4);
2340     }
2341 
2342     private static void setJavaLangAccess() {
2343         // Allow privileged classes outside of java.lang
2344         SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
2345             public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
2346                 return klass.getDeclaredPublicMethods(name, parameterTypes);
2347             }
2348             public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
2349                 return klass.getConstantPool();
2350             }
2351             public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
2352                 return klass.casAnnotationType(oldType, newType);
2353             }
2354             public AnnotationType getAnnotationType(Class<?> klass) {
2355                 return klass.getAnnotationType();
2356             }
2357             public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2358                 return klass.getDeclaredAnnotationMap();
2359             }
2360             public byte[] getRawClassAnnotations(Class<?> klass) {
2361                 return klass.getRawAnnotations();
2362             }
2363             public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2364                 return klass.getRawTypeAnnotations();
2365             }
2366             public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2367                 return Class.getExecutableTypeAnnotationBytes(executable);
2368             }
2369             public <E extends Enum<E>>
2370             E[] getEnumConstantsShared(Class<E> klass) {
2371                 return klass.getEnumConstantsShared();
2372             }
2373             public void blockedOn(Interruptible b) {
2374                 Thread.blockedOn(b);
2375             }
2376             public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2377                 Shutdown.add(slot, registerShutdownInProgress, hook);
2378             }
2379             public Thread newThreadWithAcc(Runnable target, @SuppressWarnings("removal") AccessControlContext acc) {
2380                 return new Thread(target, acc);
2381             }
2382             @SuppressWarnings("removal")
2383             public void invokeFinalize(Object o) throws Throwable {
2384                 o.finalize();
2385             }
2386             public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2387                 return cl.createOrGetClassLoaderValueMap();
2388             }
2389             public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2390                 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2391             }
2392             public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd,
2393                                         boolean initialize, int flags, Object classData) {
2394                 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData);
2395             }
2396             public Class<?> findBootstrapClassOrNull(String name) {
2397                 return ClassLoader.findBootstrapClassOrNull(name);
2398             }
2399             public Package definePackage(ClassLoader cl, String name, Module module) {
2400                 return cl.definePackage(name, module);
2401             }
2402             @SuppressWarnings("removal")
2403             public void addNonExportedPackages(ModuleLayer layer) {
2404                 SecurityManager.addNonExportedPackages(layer);
2405             }
2406             @SuppressWarnings("removal")
2407             public void invalidatePackageAccessCache() {
2408                 SecurityManager.invalidatePackageAccessCache();
2409             }
2410             public Module defineModule(ClassLoader loader,
2411                                        ModuleDescriptor descriptor,
2412                                        URI uri) {
2413                 return new Module(null, loader, descriptor, uri);
2414             }
2415             public Module defineUnnamedModule(ClassLoader loader) {
2416                 return new Module(loader);
2417             }
2418             public void addReads(Module m1, Module m2) {
2419                 m1.implAddReads(m2);
2420             }
2421             public void addReadsAllUnnamed(Module m) {
2422                 m.implAddReadsAllUnnamed();
2423             }
2424             public void addExports(Module m, String pn) {
2425                 m.implAddExports(pn);
2426             }
2427             public void addExports(Module m, String pn, Module other) {
2428                 m.implAddExports(pn, other);
2429             }
2430             public void addExportsToAllUnnamed(Module m, String pn) {
2431                 m.implAddExportsToAllUnnamed(pn);
2432             }
2433             public void addOpens(Module m, String pn, Module other) {
2434                 m.implAddOpens(pn, other);
2435             }
2436             public void addOpensToAllUnnamed(Module m, String pn) {
2437                 m.implAddOpensToAllUnnamed(pn);
2438             }
2439             public void addOpensToAllUnnamed(Module m, Set<String> concealedPackages, Set<String> exportedPackages) {
2440                 m.implAddOpensToAllUnnamed(concealedPackages, exportedPackages);
2441             }
2442             public void addUses(Module m, Class<?> service) {
2443                 m.implAddUses(service);
2444             }
2445             public boolean isReflectivelyExported(Module m, String pn, Module other) {
2446                 return m.isReflectivelyExported(pn, other);
2447             }
2448             public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2449                 return m.isReflectivelyOpened(pn, other);
2450             }
2451             public Module addEnableNativeAccess(Module m) {
2452                 return m.implAddEnableNativeAccess();
2453             }
2454             public void addEnableNativeAccessToAllUnnamed() {
2455                 Module.implAddEnableNativeAccessToAllUnnamed();
2456             }
2457             public void ensureNativeAccess(Module m, Class<?> owner, String methodName, Class<?> currentClass) {
2458                 m.ensureNativeAccess(owner, methodName, currentClass);
2459             }
2460             public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2461                 return layer.getServicesCatalog();
2462             }
2463             public void bindToLoader(ModuleLayer layer, ClassLoader loader) {
2464                 layer.bindToLoader(loader);
2465             }
2466             public Stream<ModuleLayer> layers(ModuleLayer layer) {
2467                 return layer.layers();
2468             }
2469             public Stream<ModuleLayer> layers(ClassLoader loader) {
2470                 return ModuleLayer.layers(loader);
2471             }
2472 
2473             public int countPositives(byte[] bytes, int offset, int length) {
2474                 return StringCoding.countPositives(bytes, offset, length);
2475             }
2476             public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException  {
2477                 return String.newStringNoRepl(bytes, cs);
2478             }
2479             public char getUTF16Char(byte[] bytes, int index) {
2480                 return StringUTF16.getChar(bytes, index);
2481             }
2482             public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2483                 return String.getBytesNoRepl(s, cs);
2484             }
2485 
2486             public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2487                 return String.newStringUTF8NoRepl(bytes, off, len, true);
2488             }
2489 
2490             public byte[] getBytesUTF8NoRepl(String s) {
2491                 return String.getBytesUTF8NoRepl(s);
2492             }
2493 
2494             public void inflateBytesToChars(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2495                 StringLatin1.inflate(src, srcOff, dst, dstOff, len);
2496             }
2497 
2498             public int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2499                 return String.decodeASCII(src, srcOff, dst, dstOff, len);
2500             }
2501 
2502             public int encodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len) {
2503                 return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
2504             }
2505 
2506             public InputStream initialSystemIn() {
2507                 return initialIn;
2508             }
2509 
2510             public void setCause(Throwable t, Throwable cause) {
2511                 t.setCause(cause);
2512             }
2513 
2514             public ProtectionDomain protectionDomain(Class<?> c) {
2515                 return c.protectionDomain();
2516             }
2517 
2518             public MethodHandle stringConcatHelper(String name, MethodType methodType) {
2519                 return StringConcatHelper.lookupStatic(name, methodType);
2520             }
2521 
2522             public long stringConcatInitialCoder() {
2523                 return StringConcatHelper.initialCoder();
2524             }
2525 
2526             public long stringConcatMix(long lengthCoder, String constant) {
2527                 return StringConcatHelper.mix(lengthCoder, constant);
2528             }
2529 
2530             @PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
2531             public long stringConcatCoder(char value) {
2532                 return StringConcatHelper.coder(value);
2533             }
2534 
2535             @PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
2536             public long stringBuilderConcatMix(long lengthCoder,
2537                                                StringBuilder sb) {
2538                 return sb.mix(lengthCoder);
2539             }
2540 
2541             @PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
2542             public long stringBuilderConcatPrepend(long lengthCoder, byte[] buf,
2543                                                    StringBuilder sb) {
2544                 return sb.prepend(lengthCoder, buf);
2545             }
2546 
2547             public String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
2548                 return String.join(prefix, suffix, delimiter, elements, size);
2549             }
2550 
2551             public Object classData(Class<?> c) {
2552                 return c.getClassData();
2553             }
2554 
2555             @Override
2556             public long findNative(ClassLoader loader, String entry) {
2557                 return ClassLoader.findNative(loader, entry);
2558             }
2559 
2560             @Override
2561             public void exit(int statusCode) {
2562                 Shutdown.exit(statusCode);
2563             }
2564 
2565             public Thread[] getAllThreads() {
2566                 return Thread.getAllThreads();
2567             }
2568 
2569             public ThreadContainer threadContainer(Thread thread) {
2570                 return thread.threadContainer();
2571             }
2572 
2573             public void start(Thread thread, ThreadContainer container) {
2574                 thread.start(container);
2575             }
2576 
2577             public StackableScope headStackableScope(Thread thread) {
2578                 return thread.headStackableScopes();
2579             }
2580 
2581             public void setHeadStackableScope(StackableScope scope) {
2582                 Thread.setHeadStackableScope(scope);
2583             }
2584 
2585             public Thread currentCarrierThread() {
2586                 return Thread.currentCarrierThread();
2587             }
2588 
2589             public <V> V executeOnCarrierThread(Callable<V> task) throws Exception {
2590                 if (Thread.currentThread() instanceof VirtualThread vthread) {
2591                     return vthread.executeOnCarrierThread(task);
2592                 } else {
2593                     return task.call();
2594                 }
2595             }
2596 
2597             public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
2598                 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
2599             }
2600 
2601             public <T> void setCarrierThreadLocal(CarrierThreadLocal<T> local, T value) {
2602                 ((ThreadLocal<T>)local).setCarrierThreadLocal(value);
2603             }
2604 
2605             public void removeCarrierThreadLocal(CarrierThreadLocal<?> local) {
2606                 ((ThreadLocal<?>)local).removeCarrierThreadLocal();
2607             }
2608 
2609             public boolean isCarrierThreadLocalPresent(CarrierThreadLocal<?> local) {
2610                 return ((ThreadLocal<?>)local).isCarrierThreadLocalPresent();
2611             }
2612 
2613             public Object[] scopedValueCache() {
2614                 return Thread.scopedValueCache();
2615             }
2616 
2617             public void setScopedValueCache(Object[] cache) {
2618                 Thread.setScopedValueCache(cache);
2619             }
2620 
2621             public Object scopedValueBindings() {
2622                 return Thread.scopedValueBindings();
2623             }
2624 
2625             public Continuation getContinuation(Thread thread) {
2626                 return thread.getContinuation();
2627             }
2628 
2629             public void setContinuation(Thread thread, Continuation continuation) {
2630                 thread.setContinuation(continuation);
2631             }
2632 
2633             public ContinuationScope virtualThreadContinuationScope() {
2634                 return VirtualThread.continuationScope();
2635             }
2636 
2637             public void parkVirtualThread() {
2638                 Thread thread = Thread.currentThread();
2639                 if (thread instanceof BaseVirtualThread vthread) {
2640                     vthread.park();
2641                 } else {
2642                     throw new WrongThreadException();
2643                 }
2644             }
2645 
2646             public void parkVirtualThread(long nanos) {
2647                 Thread thread = Thread.currentThread();
2648                 if (thread instanceof BaseVirtualThread vthread) {
2649                     vthread.parkNanos(nanos);
2650                 } else {
2651                     throw new WrongThreadException();
2652                 }
2653             }
2654 
2655             public void unparkVirtualThread(Thread thread) {
2656                 if (thread instanceof BaseVirtualThread vthread) {
2657                     vthread.unpark();
2658                 } else {
2659                     throw new WrongThreadException();
2660                 }
2661             }
2662 
2663             public StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
2664                                                       ContinuationScope contScope,
2665                                                       Continuation continuation) {
2666                 return StackWalker.newInstance(options, null, contScope, continuation);
2667             }
2668 
2669             public String getLoaderNameID(ClassLoader loader) {
2670                 return loader != null ? loader.nameAndId() : "null";
2671             }
2672 
2673             @Override
2674             public void copyToSegmentRaw(String string, MemorySegment segment, long offset) {
2675                 string.copyToSegmentRaw(segment, offset);
2676             }
2677 
2678             @Override
2679             public boolean bytesCompatible(String string, Charset charset) {
2680                 return string.bytesCompatible(charset);
2681             }
2682         });
2683     }
2684 }