Source for java.lang.Runtime

   1: /* Runtime.java -- access to the VM process
   2:    Copyright (C) 1998, 2002, 2003, 2004, 2005, 2006 Free Software Foundation
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.lang;
  40: 
  41: import gnu.classpath.SystemProperties;
  42: 
  43: import java.io.File;
  44: import java.io.IOException;
  45: import java.io.InputStream;
  46: import java.io.OutputStream;
  47: import java.util.HashSet;
  48: import java.util.Iterator;
  49: import java.util.Set;
  50: import java.util.StringTokenizer;
  51: 
  52: /**
  53:  * Runtime represents the Virtual Machine.
  54:  *
  55:  * @author John Keiser
  56:  * @author Eric Blake (ebb9@email.byu.edu)
  57:  * @author Jeroen Frijters
  58:  */
  59: // No idea why this class isn't final, since you can't build a subclass!
  60: public class Runtime
  61: {
  62:   /**
  63:    * The library path, to search when loading libraries. We can also safely use
  64:    * this as a lock for synchronization.
  65:    */
  66:   private final String[] libpath;
  67: 
  68:   static
  69:   {
  70:     init();
  71:   }
  72: 
  73:   /**
  74:    * The thread that started the exit sequence. Access to this field must
  75:    * be thread-safe; lock on libpath to avoid deadlock with user code.
  76:    * <code>runFinalization()</code> may want to look at this to see if ALL
  77:    * finalizers should be run, because the virtual machine is about to halt.
  78:    */
  79:   private Thread exitSequence;
  80: 
  81:   /**
  82:    * All shutdown hooks. This is initialized lazily, and set to null once all
  83:    * shutdown hooks have run. Access to this field must be thread-safe; lock
  84:    * on libpath to avoid deadlock with user code.
  85:    */
  86:   private Set shutdownHooks;
  87: 
  88:   /** True if we should finalize on exit.  */
  89:   private boolean finalizeOnExit;
  90: 
  91:   /**
  92:    * The one and only runtime instance.
  93:    */
  94:   private static final Runtime current = new Runtime();
  95: 
  96:   /**
  97:    * Not instantiable by a user, this should only create one instance.
  98:    */
  99:   private Runtime()
 100:   {
 101:     if (current != null)
 102:       throw new InternalError("Attempt to recreate Runtime");
 103:     
 104:     // We don't use libpath in the libgcj implementation.  We still
 105:     // set it to something to allow the various synchronizations to
 106:     // work.
 107:     libpath = new String[0];
 108:   }
 109: 
 110:   /**
 111:    * Get the current Runtime object for this JVM. This is necessary to access
 112:    * the many instance methods of this class.
 113:    *
 114:    * @return the current Runtime object
 115:    */
 116:   public static Runtime getRuntime()
 117:   {
 118:     return current;
 119:   }
 120: 
 121:   /**
 122:    * Exit the Java runtime. This method will either throw a SecurityException
 123:    * or it will never return. The status code is returned to the system; often
 124:    * a non-zero status code indicates an abnormal exit. Of course, there is a
 125:    * security check, <code>checkExit(status)</code>.
 126:    *
 127:    * <p>First, all shutdown hooks are run, in unspecified order, and
 128:    * concurrently. Next, if finalization on exit has been enabled, all pending
 129:    * finalizers are run. Finally, the system calls <code>halt</code>.</p>
 130:    *
 131:    * <p>If this is run a second time after shutdown has already started, there
 132:    * are two actions. If shutdown hooks are still executing, it blocks
 133:    * indefinitely. Otherwise, if the status is nonzero it halts immediately;
 134:    * if it is zero, it blocks indefinitely. This is typically called by
 135:    * <code>System.exit</code>.</p>
 136:    *
 137:    * @param status the status to exit with
 138:    * @throws SecurityException if permission is denied
 139:    * @see #addShutdownHook(Thread)
 140:    * @see #runFinalizersOnExit(boolean)
 141:    * @see #runFinalization()
 142:    * @see #halt(int)
 143:    */
 144:   public void exit(int status)
 145:   {
 146:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 147:     if (sm != null)
 148:       sm.checkExit(status);
 149: 
 150:     if (runShutdownHooks())
 151:       halt(status);
 152: 
 153:     // Someone else already called runShutdownHooks().
 154:     // Make sure we are not/no longer in the shutdownHooks set.
 155:     // And wait till the thread that is calling runShutdownHooks() finishes.
 156:     synchronized (libpath)
 157:       {
 158:         if (shutdownHooks != null)
 159:           {
 160:             shutdownHooks.remove(Thread.currentThread());
 161:             // Interrupt the exit sequence thread, in case it was waiting
 162:             // inside a join on our thread.
 163:             exitSequence.interrupt();
 164:             // Shutdown hooks are still running, so we clear status to
 165:         // make sure we don't halt.
 166:         status = 0;
 167:           }
 168:       }
 169: 
 170:     // If exit() is called again after the shutdown hooks have run, but
 171:     // while finalization for exit is going on and the status is non-zero
 172:     // we halt immediately.
 173:     if (status != 0)
 174:       halt(status);
 175: 
 176:     while (true)
 177:       try
 178:         {
 179:           exitSequence.join();
 180:         }
 181:       catch (InterruptedException e)
 182:         {
 183:           // Ignore, we've suspended indefinitely to let all shutdown
 184:           // hooks complete, and to let any non-zero exits through, because
 185:           // this is a duplicate call to exit(0).
 186:         }
 187:   }
 188: 
 189:   /**
 190:    * On first invocation, run all the shutdown hooks and return true.
 191:    * Any subsequent invocations will simply return false.
 192:    * Note that it is package accessible so that VMRuntime can call it
 193:    * when VM exit is not triggered by a call to Runtime.exit().
 194:    * 
 195:    * @return was the current thread the first one to call this method?
 196:    */
 197:   boolean runShutdownHooks()
 198:   {
 199:     boolean first = false;
 200:     synchronized (libpath) // Synch on libpath, not this, to avoid deadlock.
 201:       {
 202:         if (exitSequence == null)
 203:           {
 204:             first = true;
 205:             exitSequence = Thread.currentThread();
 206:             if (shutdownHooks != null)
 207:               {
 208:                 Iterator i = shutdownHooks.iterator();
 209:                 while (i.hasNext()) // Start all shutdown hooks.
 210:                   try
 211:                     {
 212:                       ((Thread) i.next()).start();
 213:                     }
 214:                   catch (IllegalThreadStateException e)
 215:                     {
 216:                       i.remove();
 217:                     }
 218:               }
 219:           }
 220:       }
 221:     if (first)
 222:       {
 223:         if (shutdownHooks != null)
 224:           {
 225:             // Check progress of all shutdown hooks. As a hook completes,
 226:             // remove it from the set. If a hook calls exit, it removes
 227:             // itself from the set, then waits indefinitely on the
 228:             // exitSequence thread. Once the set is empty, set it to null to
 229:             // signal all finalizer threads that halt may be called.
 230:             while (true)
 231:               {
 232:                 Thread[] hooks;
 233:                 synchronized (libpath)
 234:                   {
 235:                     hooks = new Thread[shutdownHooks.size()];
 236:                     shutdownHooks.toArray(hooks);
 237:                   }
 238:                 if (hooks.length == 0)
 239:                   break;
 240:                 for (int i = 0; i < hooks.length; i++)
 241:                   {
 242:                     try
 243:                       {
 244:                         synchronized (libpath)
 245:                           {
 246:                             if (!shutdownHooks.contains(hooks[i]))
 247:                               continue;
 248:                           }
 249:                         hooks[i].join();
 250:                         synchronized (libpath)
 251:                           {
 252:                             shutdownHooks.remove(hooks[i]);
 253:                           }
 254:                       }
 255:                     catch (InterruptedException x)
 256:                       {
 257:                         // continue waiting on the next thread
 258:                       }
 259:                   }
 260:               }
 261:             synchronized (libpath)
 262:               {
 263:                 shutdownHooks = null;
 264:               }
 265:           }
 266:     // Run finalization on all finalizable objects (even if they are
 267:     // still reachable).
 268:         runFinalizationForExit();
 269:       }
 270:     return first;
 271:   }
 272: 
 273:   /**
 274:    * Register a new shutdown hook. This is invoked when the program exits
 275:    * normally (because all non-daemon threads ended, or because
 276:    * <code>System.exit</code> was invoked), or when the user terminates
 277:    * the virtual machine (such as by typing ^C, or logging off). There is
 278:    * a security check to add hooks,
 279:    * <code>RuntimePermission("shutdownHooks")</code>.
 280:    *
 281:    * <p>The hook must be an initialized, but unstarted Thread. The threads
 282:    * are run concurrently, and started in an arbitrary order; and user
 283:    * threads or daemons may still be running. Once shutdown hooks have
 284:    * started, they must all complete, or else you must use <code>halt</code>,
 285:    * to actually finish the shutdown sequence. Attempts to modify hooks
 286:    * after shutdown has started result in IllegalStateExceptions.</p>
 287:    *
 288:    * <p>It is imperative that you code shutdown hooks defensively, as you
 289:    * do not want to deadlock, and have no idea what other hooks will be
 290:    * running concurrently. It is also a good idea to finish quickly, as the
 291:    * virtual machine really wants to shut down!</p>
 292:    *
 293:    * <p>There are no guarantees that such hooks will run, as there are ways
 294:    * to forcibly kill a process. But in such a drastic case, shutdown hooks
 295:    * would do little for you in the first place.</p>
 296:    *
 297:    * @param hook an initialized, unstarted Thread
 298:    * @throws IllegalArgumentException if the hook is already registered or run
 299:    * @throws IllegalStateException if the virtual machine is already in
 300:    *         the shutdown sequence
 301:    * @throws SecurityException if permission is denied
 302:    * @since 1.3
 303:    * @see #removeShutdownHook(Thread)
 304:    * @see #exit(int)
 305:    * @see #halt(int)
 306:    */
 307:   public void addShutdownHook(Thread hook)
 308:   {
 309:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 310:     if (sm != null)
 311:       sm.checkPermission(new RuntimePermission("shutdownHooks"));
 312:     if (hook.isAlive() || hook.getThreadGroup() == null)
 313:       throw new IllegalArgumentException("The hook thread " + hook + " must not have been already run or started");
 314:     synchronized (libpath)
 315:       {
 316:         if (exitSequence != null)
 317:           throw new IllegalStateException("The Virtual Machine is exiting. It is not possible anymore to add any hooks");
 318:         if (shutdownHooks == null)
 319:           shutdownHooks = new HashSet(); // Lazy initialization.
 320:         if (! shutdownHooks.add(hook))
 321:           throw new IllegalArgumentException(hook.toString() + " had already been inserted");
 322:       }
 323:   }
 324: 
 325:   /**
 326:    * De-register a shutdown hook. As when you registered it, there is a
 327:    * security check to remove hooks,
 328:    * <code>RuntimePermission("shutdownHooks")</code>.
 329:    *
 330:    * @param hook the hook to remove
 331:    * @return true if the hook was successfully removed, false if it was not
 332:    *         registered in the first place
 333:    * @throws IllegalStateException if the virtual machine is already in
 334:    *         the shutdown sequence
 335:    * @throws SecurityException if permission is denied
 336:    * @since 1.3
 337:    * @see #addShutdownHook(Thread)
 338:    * @see #exit(int)
 339:    * @see #halt(int)
 340:    */
 341:   public boolean removeShutdownHook(Thread hook)
 342:   {
 343:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 344:     if (sm != null)
 345:       sm.checkPermission(new RuntimePermission("shutdownHooks"));
 346:     synchronized (libpath)
 347:       {
 348:         if (exitSequence != null)
 349:           throw new IllegalStateException();
 350:         if (shutdownHooks != null)
 351:           return shutdownHooks.remove(hook);
 352:       }
 353:     return false;
 354:   }
 355: 
 356:   /**
 357:    * Forcibly terminate the virtual machine. This call never returns. It is
 358:    * much more severe than <code>exit</code>, as it bypasses all shutdown
 359:    * hooks and initializers. Use caution in calling this! Of course, there is
 360:    * a security check, <code>checkExit(status)</code>.
 361:    *
 362:    * @param status the status to exit with
 363:    * @throws SecurityException if permission is denied
 364:    * @since 1.3
 365:    * @see #exit(int)
 366:    * @see #addShutdownHook(Thread)
 367:    */
 368:   public void halt(int status)
 369:   {
 370:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 371:     if (sm != null)
 372:       sm.checkExit(status);
 373:     exitInternal(status);
 374:   }
 375: 
 376:   /**
 377:    * Tell the VM to run the finalize() method on every single Object before
 378:    * it exits.  Note that the JVM may still exit abnormally and not perform
 379:    * this, so you still don't have a guarantee. And besides that, this is
 380:    * inherently unsafe in multi-threaded code, as it may result in deadlock
 381:    * as multiple threads compete to manipulate objects. This value defaults to
 382:    * <code>false</code>. There is a security check, <code>checkExit(0)</code>.
 383:    *
 384:    * @param finalizeOnExit whether to finalize all Objects on exit
 385:    * @throws SecurityException if permission is denied
 386:    * @see #exit(int)
 387:    * @see #gc()
 388:    * @since 1.1
 389:    * @deprecated never rely on finalizers to do a clean, thread-safe,
 390:    *             mop-up from your code
 391:    */
 392:   public static void runFinalizersOnExit(boolean finalizeOnExit)
 393:   {
 394:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 395:     if (sm != null)
 396:       sm.checkExit(0);
 397:     current.finalizeOnExit = finalizeOnExit;
 398:   }
 399: 
 400:   /**
 401:    * Create a new subprocess with the specified command line. Calls
 402:    * <code>exec(cmdline, null, null)</code>. A security check is performed,
 403:    * <code>checkExec</code>.
 404:    *
 405:    * @param cmdline the command to call
 406:    * @return the Process object
 407:    * @throws SecurityException if permission is denied
 408:    * @throws IOException if an I/O error occurs
 409:    * @throws NullPointerException if cmdline is null
 410:    * @throws IndexOutOfBoundsException if cmdline is ""
 411:    */
 412:   public Process exec(String cmdline) throws IOException
 413:   {
 414:     return exec(cmdline, null, null);
 415:   }
 416: 
 417:   /**
 418:    * Create a new subprocess with the specified command line and environment.
 419:    * If the environment is null, the process inherits the environment of
 420:    * this process. Calls <code>exec(cmdline, env, null)</code>. A security
 421:    * check is performed, <code>checkExec</code>.
 422:    *
 423:    * @param cmdline the command to call
 424:    * @param env the environment to use, in the format name=value
 425:    * @return the Process object
 426:    * @throws SecurityException if permission is denied
 427:    * @throws IOException if an I/O error occurs
 428:    * @throws NullPointerException if cmdline is null, or env has null entries
 429:    * @throws IndexOutOfBoundsException if cmdline is ""
 430:    */
 431:   public Process exec(String cmdline, String[] env) throws IOException
 432:   {
 433:     return exec(cmdline, env, null);
 434:   }
 435: 
 436:   /**
 437:    * Create a new subprocess with the specified command line, environment, and
 438:    * working directory. If the environment is null, the process inherits the
 439:    * environment of this process. If the directory is null, the process uses
 440:    * the current working directory. This splits cmdline into an array, using
 441:    * the default StringTokenizer, then calls
 442:    * <code>exec(cmdArray, env, dir)</code>. A security check is performed,
 443:    * <code>checkExec</code>.
 444:    *
 445:    * @param cmdline the command to call
 446:    * @param env the environment to use, in the format name=value
 447:    * @param dir the working directory to use
 448:    * @return the Process object
 449:    * @throws SecurityException if permission is denied
 450:    * @throws IOException if an I/O error occurs
 451:    * @throws NullPointerException if cmdline is null, or env has null entries
 452:    * @throws IndexOutOfBoundsException if cmdline is ""
 453:    * @since 1.3
 454:    */
 455:   public Process exec(String cmdline, String[] env, File dir)
 456:     throws IOException
 457:   {
 458:     StringTokenizer t = new StringTokenizer(cmdline);
 459:     String[] cmd = new String[t.countTokens()];
 460:     for (int i = 0; i < cmd.length; i++)
 461:       cmd[i] = t.nextToken();
 462:     return exec(cmd, env, dir);
 463:   }
 464: 
 465:   /**
 466:    * Create a new subprocess with the specified command line, already
 467:    * tokenized. Calls <code>exec(cmd, null, null)</code>. A security check
 468:    * is performed, <code>checkExec</code>.
 469:    *
 470:    * @param cmd the command to call
 471:    * @return the Process object
 472:    * @throws SecurityException if permission is denied
 473:    * @throws IOException if an I/O error occurs
 474:    * @throws NullPointerException if cmd is null, or has null entries
 475:    * @throws IndexOutOfBoundsException if cmd is length 0
 476:    */
 477:   public Process exec(String[] cmd) throws IOException
 478:   {
 479:     return exec(cmd, null, null);
 480:   }
 481: 
 482:   /**
 483:    * Create a new subprocess with the specified command line, already
 484:    * tokenized, and specified environment. If the environment is null, the
 485:    * process inherits the environment of this process. Calls
 486:    * <code>exec(cmd, env, null)</code>. A security check is performed,
 487:    * <code>checkExec</code>.
 488:    *
 489:    * @param cmd the command to call
 490:    * @param env the environment to use, in the format name=value
 491:    * @return the Process object
 492:    * @throws SecurityException if permission is denied
 493:    * @throws IOException if an I/O error occurs
 494:    * @throws NullPointerException if cmd is null, or cmd or env has null
 495:    *         entries
 496:    * @throws IndexOutOfBoundsException if cmd is length 0
 497:    */
 498:   public Process exec(String[] cmd, String[] env) throws IOException
 499:   {
 500:     return exec(cmd, env, null);
 501:   }
 502: 
 503:   /**
 504:    * Create a new subprocess with the specified command line, already
 505:    * tokenized, and the specified environment and working directory. If the
 506:    * environment is null, the process inherits the environment of this
 507:    * process. If the directory is null, the process uses the current working
 508:    * directory. A security check is performed, <code>checkExec</code>.
 509:    *
 510:    * @param cmd the command to call
 511:    * @param env the environment to use, in the format name=value
 512:    * @param dir the working directory to use
 513:    * @return the Process object
 514:    * @throws SecurityException if permission is denied
 515:    * @throws IOException if an I/O error occurs
 516:    * @throws NullPointerException if cmd is null, or cmd or env has null
 517:    *         entries
 518:    * @throws IndexOutOfBoundsException if cmd is length 0
 519:    * @since 1.3
 520:    */
 521:   public Process exec(String[] cmd, String[] env, File dir)
 522:     throws IOException
 523:   {
 524:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 525:     if (sm != null)
 526:       sm.checkExec(cmd[0]);
 527:     return execInternal(cmd, env, dir);
 528:   }
 529: 
 530:   /**
 531:    * Returns the number of available processors currently available to the
 532:    * virtual machine. This number may change over time; so a multi-processor
 533:    * program want to poll this to determine maximal resource usage.
 534:    *
 535:    * @return the number of processors available, at least 1
 536:    */
 537:   public native int availableProcessors();
 538: 
 539:   /**
 540:    * Find out how much memory is still free for allocating Objects on the heap.
 541:    *
 542:    * @return the number of bytes of free memory for more Objects
 543:    */
 544:   public native long freeMemory();
 545: 
 546:   /**
 547:    * Find out how much memory total is available on the heap for allocating
 548:    * Objects.
 549:    *
 550:    * @return the total number of bytes of memory for Objects
 551:    */
 552:   public native long totalMemory();
 553: 
 554:   /**
 555:    * Returns the maximum amount of memory the virtual machine can attempt to
 556:    * use. This may be <code>Long.MAX_VALUE</code> if there is no inherent
 557:    * limit (or if you really do have a 8 exabyte memory!).
 558:    *
 559:    * @return the maximum number of bytes the virtual machine will attempt
 560:    *         to allocate
 561:    */
 562:   public native long maxMemory();
 563: 
 564:   /**
 565:    * Run the garbage collector. This method is more of a suggestion than
 566:    * anything. All this method guarantees is that the garbage collector will
 567:    * have "done its best" by the time it returns. Notice that garbage
 568:    * collection takes place even without calling this method.
 569:    */
 570:   public native void gc();
 571: 
 572:   /**
 573:    * Run finalization on all Objects that are waiting to be finalized. Again,
 574:    * a suggestion, though a stronger one than {@link #gc()}. This calls the
 575:    * <code>finalize</code> method of all objects waiting to be collected.
 576:    *
 577:    * @see #finalize()
 578:    */
 579:   public native void runFinalization();
 580: 
 581:   /**
 582:    * Tell the VM to trace every bytecode instruction that executes (print out
 583:    * a trace of it).  No guarantees are made as to where it will be printed,
 584:    * and the VM is allowed to ignore this request.
 585:    *
 586:    * @param on whether to turn instruction tracing on
 587:    */
 588:   public native void traceInstructions(boolean on);
 589: 
 590:   /**
 591:    * Tell the VM to trace every method call that executes (print out a trace
 592:    * of it).  No guarantees are made as to where it will be printed, and the
 593:    * VM is allowed to ignore this request.
 594:    *
 595:    * @param on whether to turn method tracing on
 596:    */
 597:   public native void traceMethodCalls(boolean on);
 598: 
 599:   /**
 600:    * Load a native library using the system-dependent filename. This is similar
 601:    * to loadLibrary, except the only name mangling done is inserting "_g"
 602:    * before the final ".so" if the VM was invoked by the name "java_g". There
 603:    * may be a security check, of <code>checkLink</code>.
 604:    *
 605:    * @param filename the file to load
 606:    * @throws SecurityException if permission is denied
 607:    * @throws UnsatisfiedLinkError if the library is not found
 608:    */
 609:   public void load(String filename)
 610:   {
 611:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 612:     if (sm != null)
 613:       sm.checkLink(filename);
 614:     _load(filename, false);
 615:   }
 616: 
 617:   /**
 618:    * Load a native library using a system-independent "short name" for the
 619:    * library.  It will be transformed to a correct filename in a
 620:    * system-dependent manner (for example, in Windows, "mylib" will be turned
 621:    * into "mylib.dll").  This is done as follows: if the context that called
 622:    * load has a ClassLoader cl, then <code>cl.findLibrary(libpath)</code> is
 623:    * used to convert the name. If that result was null, or there was no class
 624:    * loader, this searches each directory of the system property
 625:    * <code>java.library.path</code> for a file named
 626:    * <code>System.mapLibraryName(libname)</code>. There may be a security
 627:    * check, of <code>checkLink</code>.
 628:    *
 629:    * @param libname the library to load
 630:    *
 631:    * @throws SecurityException if permission is denied
 632:    * @throws UnsatisfiedLinkError if the library is not found
 633:    *
 634:    * @see System#mapLibraryName(String)
 635:    * @see ClassLoader#findLibrary(String)
 636:    */
 637:   public void loadLibrary(String libname)
 638:   {
 639:     // This is different from the Classpath implementation, but I
 640:     // believe it is more correct.
 641:     SecurityManager sm = SecurityManager.current; // Be thread-safe!
 642:     if (sm != null)
 643:       sm.checkLink(libname);
 644:     _load(libname, true);
 645:   }
 646: 
 647:   /**
 648:    * Return a localized version of this InputStream, meaning all characters
 649:    * are localized before they come out the other end.
 650:    *
 651:    * @param in the stream to localize
 652:    * @return the localized stream
 653:    * @deprecated <code>InputStreamReader</code> is the preferred way to read
 654:    *             local encodings
 655:    */
 656:   public InputStream getLocalizedInputStream(InputStream in)
 657:   {
 658:     return in;
 659:   }
 660: 
 661:   /**
 662:    * Return a localized version of this OutputStream, meaning all characters
 663:    * are localized before they are sent to the other end.
 664:    *
 665:    * @param out the stream to localize
 666:    * @return the localized stream
 667:    * @deprecated <code>OutputStreamWriter</code> is the preferred way to write
 668:    *             local encodings
 669:    */
 670:   public OutputStream getLocalizedOutputStream(OutputStream out)
 671:   {
 672:     return out;
 673:   }
 674: 
 675:   /**
 676:    * Native method that actually shuts down the virtual machine.
 677:    *
 678:    * @param status the status to end the process with
 679:    */
 680:   native void exitInternal(int status);
 681: 
 682:   /**
 683:    * Load a file. If it has already been loaded, do nothing. The name has
 684:    * already been mapped to a true filename.
 685:    *
 686:    * @param filename the file to load
 687:    * @param do_search True if we should search the load path for the file
 688:    */
 689:   native void _load(String filename, boolean do_search);
 690: 
 691:   /**
 692:    *This is a helper function for the ClassLoader which can load
 693:    * compiled libraries.  Returns true if library (which is just the
 694:    * base name -- path searching is done by this function) was loaded,
 695:    * false otherwise.
 696:    */
 697:   native boolean loadLibraryInternal(String libname);
 698: 
 699:   /**
 700:    * A helper for Runtime static initializer which does some internal native
 701:    * initialization.
 702:    */
 703:   private static native void init ();
 704: 
 705:   /**
 706:    * Run finalizers when exiting.
 707:    */
 708:   private native void runFinalizationForExit();
 709: 
 710:   /**
 711:    * Map a system-independent "short name" to the full file name, and append
 712:    * it to the path.
 713:    * XXX This method is being replaced by System.mapLibraryName.
 714:    *
 715:    * @param pathname the path
 716:    * @param libname the short version of the library name
 717:    * @return the full filename
 718:    */
 719:   static native String nativeGetLibname(String pathname, String libname);
 720: 
 721:   /**
 722:    * Execute a process. The command line has already been tokenized, and
 723:    * the environment should contain name=value mappings. If directory is null,
 724:    * use the current working directory; otherwise start the process in that
 725:    * directory.
 726:    *
 727:    * @param cmd the non-null command tokens
 728:    * @param env the non-null environment setup
 729:    * @param dir the directory to use, may be null
 730:    * @return the newly created process
 731:    * @throws NullPointerException if cmd or env have null elements
 732:    * @throws IOException if the exec fails
 733:    */
 734:   native Process execInternal(String[] cmd, String[] env, File dir)
 735:     throws IOException;
 736: } // class Runtime