001/* Runtime.java -- access to the VM process
002   Copyright (C) 1998, 2002, 2003, 2004, 2005 Free Software Foundation
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.lang;
040
041import gnu.classpath.SystemProperties;
042import gnu.classpath.VMStackWalker;
043
044import java.io.File;
045import java.io.IOException;
046import java.io.InputStream;
047import java.io.OutputStream;
048import java.util.HashSet;
049import java.util.Iterator;
050import java.util.Set;
051import java.util.StringTokenizer;
052
053/**
054 * Runtime represents the Virtual Machine.
055 *
056 * @author John Keiser
057 * @author Eric Blake (ebb9@email.byu.edu)
058 * @author Jeroen Frijters
059 */
060// No idea why this class isn't final, since you can't build a subclass!
061public class Runtime
062{
063  /**
064   * The library path, to search when loading libraries. We can also safely use
065   * this as a lock for synchronization.
066   */
067  private final String[] libpath;
068
069  /**
070   * The thread that started the exit sequence. Access to this field must
071   * be thread-safe; lock on libpath to avoid deadlock with user code.
072   * <code>runFinalization()</code> may want to look at this to see if ALL
073   * finalizers should be run, because the virtual machine is about to halt.
074   */
075  private Thread exitSequence;
076
077  /**
078   * All shutdown hooks. This is initialized lazily, and set to null once all
079   * shutdown hooks have run. Access to this field must be thread-safe; lock
080   * on libpath to avoid deadlock with user code.
081   */
082  private Set shutdownHooks;
083
084  /**
085   * The one and only runtime instance.
086   */
087  private static final Runtime current = new Runtime();
088
089  /**
090   * Not instantiable by a user, this should only create one instance.
091   */
092  private Runtime()
093  {
094    if (current != null)
095      throw new InternalError("Attempt to recreate Runtime");
096
097    // If used by underlying VM this contains the directories where Classpath's own
098    // native libraries are located.
099    String bootPath = SystemProperties.getProperty("gnu.classpath.boot.library.path", "");
100
101    // If properly set by the user this contains the directories where the application's
102    // native libraries are located. On operating systems where a LD_LIBRARY_PATH environment
103    // variable is available a VM should preset java.library.path with value of this
104    // variable.
105    String path = SystemProperties.getProperty("java.library.path", ".");
106    String pathSep = SystemProperties.getProperty("path.separator", ":");
107    String fileSep = SystemProperties.getProperty("file.separator", "/");
108
109    StringTokenizer t1 = new StringTokenizer(bootPath, pathSep);
110    StringTokenizer t2 = new StringTokenizer(path, pathSep);
111    libpath = new String[t1.countTokens() + t2.countTokens()];
112
113    int i = 0;
114    while(t1.hasMoreTokens()) {
115      String prefix = t1.nextToken();
116      if (! prefix.endsWith(fileSep))
117        prefix += fileSep;
118
119      libpath[i] = prefix;
120      i++;
121    }
122
123    while(t2.hasMoreTokens()) {
124      String prefix = t2.nextToken();
125      if (! prefix.endsWith(fileSep))
126        prefix += fileSep;
127
128      libpath[i] = prefix;
129      i++;
130    }
131  }
132
133  /**
134   * Get the current Runtime object for this JVM. This is necessary to access
135   * the many instance methods of this class.
136   *
137   * @return the current Runtime object
138   */
139  public static Runtime getRuntime()
140  {
141    return current;
142  }
143
144  /**
145   * Exit the Java runtime. This method will either throw a SecurityException
146   * or it will never return. The status code is returned to the system; often
147   * a non-zero status code indicates an abnormal exit. Of course, there is a
148   * security check, <code>checkExit(status)</code>.
149   *
150   * <p>First, all shutdown hooks are run, in unspecified order, and
151   * concurrently. Next, if finalization on exit has been enabled, all pending
152   * finalizers are run. Finally, the system calls <code>halt</code>.</p>
153   *
154   * <p>If this is run a second time after shutdown has already started, there
155   * are two actions. If shutdown hooks are still executing, it blocks
156   * indefinitely. Otherwise, if the status is nonzero it halts immediately;
157   * if it is zero, it blocks indefinitely. This is typically called by
158   * <code>System.exit</code>.</p>
159   *
160   * @param status the status to exit with
161   * @throws SecurityException if permission is denied
162   * @see #addShutdownHook(Thread)
163   * @see #runFinalizersOnExit(boolean)
164   * @see #runFinalization()
165   * @see #halt(int)
166   */
167  public void exit(int status)
168  {
169    SecurityManager sm = SecurityManager.current; // Be thread-safe!
170    if (sm != null)
171      sm.checkExit(status);
172
173    if (runShutdownHooks())
174      halt(status);
175
176    // Someone else already called runShutdownHooks().
177    // Make sure we are not/no longer in the shutdownHooks set.
178    // And wait till the thread that is calling runShutdownHooks() finishes.
179    synchronized (libpath)
180      {
181        if (shutdownHooks != null)
182          {
183            shutdownHooks.remove(Thread.currentThread());
184            // Interrupt the exit sequence thread, in case it was waiting
185            // inside a join on our thread.
186            exitSequence.interrupt();
187            // Shutdown hooks are still running, so we clear status to
188            // make sure we don't halt.
189            status = 0;
190          }
191      }
192
193    // If exit() is called again after the shutdown hooks have run, but
194    // while finalization for exit is going on and the status is non-zero
195    // we halt immediately.
196    if (status != 0)
197      halt(status);
198
199    while (true)
200      try
201        {
202          exitSequence.join();
203        }
204      catch (InterruptedException e)
205        {
206          // Ignore, we've suspended indefinitely to let all shutdown
207          // hooks complete, and to let any non-zero exits through, because
208          // this is a duplicate call to exit(0).
209        }
210  }
211
212  /**
213   * On first invocation, run all the shutdown hooks and return true.
214   * Any subsequent invocations will simply return false.
215   * Note that it is package accessible so that VMRuntime can call it
216   * when VM exit is not triggered by a call to Runtime.exit().
217   *
218   * @return was the current thread the first one to call this method?
219   */
220  boolean runShutdownHooks()
221  {
222    boolean first = false;
223    synchronized (libpath) // Synch on libpath, not this, to avoid deadlock.
224      {
225        if (exitSequence == null)
226          {
227            first = true;
228            exitSequence = Thread.currentThread();
229            if (shutdownHooks != null)
230              {
231                Iterator i = shutdownHooks.iterator();
232                while (i.hasNext()) // Start all shutdown hooks.
233                  try
234                    {
235                      ((Thread) i.next()).start();
236                    }
237                  catch (IllegalThreadStateException e)
238                    {
239                      i.remove();
240                    }
241              }
242          }
243      }
244    if (first)
245      {
246        if (shutdownHooks != null)
247          {
248            // Check progress of all shutdown hooks. As a hook completes,
249            // remove it from the set. If a hook calls exit, it removes
250            // itself from the set, then waits indefinitely on the
251            // exitSequence thread. Once the set is empty, set it to null to
252            // signal all finalizer threads that halt may be called.
253            while (true)
254              {
255                Thread[] hooks;
256                synchronized (libpath)
257                  {
258                    hooks = new Thread[shutdownHooks.size()];
259                    shutdownHooks.toArray(hooks);
260                  }
261                if (hooks.length == 0)
262                  break;
263                for (int i = 0; i < hooks.length; i++)
264                  {
265                    try
266                      {
267                        synchronized (libpath)
268                          {
269                            if (!shutdownHooks.contains(hooks[i]))
270                              continue;
271                          }
272                        hooks[i].join();
273                        synchronized (libpath)
274                          {
275                            shutdownHooks.remove(hooks[i]);
276                          }
277                      }
278                    catch (InterruptedException x)
279                      {
280                        // continue waiting on the next thread
281                      }
282                  }
283              }
284            synchronized (libpath)
285              {
286                shutdownHooks = null;
287              }
288          }
289        // Run finalization on all finalizable objects (even if they are
290        // still reachable).
291        VMRuntime.runFinalizationForExit();
292      }
293    return first;
294  }
295
296  /**
297   * Register a new shutdown hook. This is invoked when the program exits
298   * normally (because all non-daemon threads ended, or because
299   * <code>System.exit</code> was invoked), or when the user terminates
300   * the virtual machine (such as by typing ^C, or logging off). There is
301   * a security check to add hooks,
302   * <code>RuntimePermission("shutdownHooks")</code>.
303   *
304   * <p>The hook must be an initialized, but unstarted Thread. The threads
305   * are run concurrently, and started in an arbitrary order; and user
306   * threads or daemons may still be running. Once shutdown hooks have
307   * started, they must all complete, or else you must use <code>halt</code>,
308   * to actually finish the shutdown sequence. Attempts to modify hooks
309   * after shutdown has started result in IllegalStateExceptions.</p>
310   *
311   * <p>It is imperative that you code shutdown hooks defensively, as you
312   * do not want to deadlock, and have no idea what other hooks will be
313   * running concurrently. It is also a good idea to finish quickly, as the
314   * virtual machine really wants to shut down!</p>
315   *
316   * <p>There are no guarantees that such hooks will run, as there are ways
317   * to forcibly kill a process. But in such a drastic case, shutdown hooks
318   * would do little for you in the first place.</p>
319   *
320   * @param hook an initialized, unstarted Thread
321   * @throws IllegalArgumentException if the hook is already registered or run
322   * @throws IllegalStateException if the virtual machine is already in
323   *         the shutdown sequence
324   * @throws SecurityException if permission is denied
325   * @since 1.3
326   * @see #removeShutdownHook(Thread)
327   * @see #exit(int)
328   * @see #halt(int)
329   */
330  public void addShutdownHook(Thread hook)
331  {
332    SecurityManager sm = SecurityManager.current; // Be thread-safe!
333    if (sm != null)
334      sm.checkPermission(new RuntimePermission("shutdownHooks"));
335    if (hook.isAlive() || hook.getThreadGroup() == null)
336      throw new IllegalArgumentException("The hook thread " + hook + " must not have been already run or started");
337    synchronized (libpath)
338      {
339        if (exitSequence != null)
340          throw new IllegalStateException("The Virtual Machine is exiting. It is not possible anymore to add any hooks");
341        if (shutdownHooks == null)
342          {
343            VMRuntime.enableShutdownHooks();
344            shutdownHooks = new HashSet(); // Lazy initialization.
345          }
346        if (! shutdownHooks.add(hook))
347          throw new IllegalArgumentException(hook.toString() + " had already been inserted");
348      }
349  }
350
351  /**
352   * De-register a shutdown hook. As when you registered it, there is a
353   * security check to remove hooks,
354   * <code>RuntimePermission("shutdownHooks")</code>.
355   *
356   * @param hook the hook to remove
357   * @return true if the hook was successfully removed, false if it was not
358   *         registered in the first place
359   * @throws IllegalStateException if the virtual machine is already in
360   *         the shutdown sequence
361   * @throws SecurityException if permission is denied
362   * @since 1.3
363   * @see #addShutdownHook(Thread)
364   * @see #exit(int)
365   * @see #halt(int)
366   */
367  public boolean removeShutdownHook(Thread hook)
368  {
369    SecurityManager sm = SecurityManager.current; // Be thread-safe!
370    if (sm != null)
371      sm.checkPermission(new RuntimePermission("shutdownHooks"));
372    synchronized (libpath)
373      {
374        if (exitSequence != null)
375          throw new IllegalStateException();
376        if (shutdownHooks != null)
377          return shutdownHooks.remove(hook);
378      }
379    return false;
380  }
381
382  /**
383   * Forcibly terminate the virtual machine. This call never returns. It is
384   * much more severe than <code>exit</code>, as it bypasses all shutdown
385   * hooks and initializers. Use caution in calling this! Of course, there is
386   * a security check, <code>checkExit(status)</code>.
387   *
388   * @param status the status to exit with
389   * @throws SecurityException if permission is denied
390   * @since 1.3
391   * @see #exit(int)
392   * @see #addShutdownHook(Thread)
393   */
394  public void halt(int status)
395  {
396    SecurityManager sm = SecurityManager.current; // Be thread-safe!
397    if (sm != null)
398      sm.checkExit(status);
399    VMRuntime.exit(status);
400  }
401
402  /**
403   * Tell the VM to run the finalize() method on every single Object before
404   * it exits.  Note that the JVM may still exit abnormally and not perform
405   * this, so you still don't have a guarantee. And besides that, this is
406   * inherently unsafe in multi-threaded code, as it may result in deadlock
407   * as multiple threads compete to manipulate objects. This value defaults to
408   * <code>false</code>. There is a security check, <code>checkExit(0)</code>.
409   *
410   * @param finalizeOnExit whether to finalize all Objects on exit
411   * @throws SecurityException if permission is denied
412   * @see #exit(int)
413   * @see #gc()
414   * @since 1.1
415   * @deprecated never rely on finalizers to do a clean, thread-safe,
416   *             mop-up from your code
417   */
418  public static void runFinalizersOnExit(boolean finalizeOnExit)
419  {
420    SecurityManager sm = SecurityManager.current; // Be thread-safe!
421    if (sm != null)
422      sm.checkExit(0);
423    VMRuntime.runFinalizersOnExit(finalizeOnExit);
424  }
425
426  /**
427   * Create a new subprocess with the specified command line. Calls
428   * <code>exec(cmdline, null, null)</code>. A security check is performed,
429   * <code>checkExec</code>.
430   *
431   * @param cmdline the command to call
432   * @return the Process object
433   * @throws SecurityException if permission is denied
434   * @throws IOException if an I/O error occurs
435   * @throws NullPointerException if cmdline is null
436   * @throws IndexOutOfBoundsException if cmdline is ""
437   */
438  public Process exec(String cmdline) throws IOException
439  {
440    return exec(cmdline, null, null);
441  }
442
443  /**
444   * Create a new subprocess with the specified command line and environment.
445   * If the environment is null, the process inherits the environment of
446   * this process. Calls <code>exec(cmdline, env, null)</code>. A security
447   * check is performed, <code>checkExec</code>.
448   *
449   * @param cmdline the command to call
450   * @param env the environment to use, in the format name=value
451   * @return the Process object
452   * @throws SecurityException if permission is denied
453   * @throws IOException if an I/O error occurs
454   * @throws NullPointerException if cmdline is null, or env has null entries
455   * @throws IndexOutOfBoundsException if cmdline is ""
456   */
457  public Process exec(String cmdline, String[] env) throws IOException
458  {
459    return exec(cmdline, env, null);
460  }
461
462  /**
463   * Create a new subprocess with the specified command line, environment, and
464   * working directory. If the environment is null, the process inherits the
465   * environment of this process. If the directory is null, the process uses
466   * the current working directory. This splits cmdline into an array, using
467   * the default StringTokenizer, then calls
468   * <code>exec(cmdArray, env, dir)</code>. A security check is performed,
469   * <code>checkExec</code>.
470   *
471   * @param cmdline the command to call
472   * @param env the environment to use, in the format name=value
473   * @param dir the working directory to use
474   * @return the Process object
475   * @throws SecurityException if permission is denied
476   * @throws IOException if an I/O error occurs
477   * @throws NullPointerException if cmdline is null, or env has null entries
478   * @throws IndexOutOfBoundsException if cmdline is ""
479   * @since 1.3
480   */
481  public Process exec(String cmdline, String[] env, File dir)
482    throws IOException
483  {
484    StringTokenizer t = new StringTokenizer(cmdline);
485    String[] cmd = new String[t.countTokens()];
486    for (int i = 0; i < cmd.length; i++)
487      cmd[i] = t.nextToken();
488    return exec(cmd, env, dir);
489  }
490
491  /**
492   * Create a new subprocess with the specified command line, already
493   * tokenized. Calls <code>exec(cmd, null, null)</code>. A security check
494   * is performed, <code>checkExec</code>.
495   *
496   * @param cmd the command to call
497   * @return the Process object
498   * @throws SecurityException if permission is denied
499   * @throws IOException if an I/O error occurs
500   * @throws NullPointerException if cmd is null, or has null entries
501   * @throws IndexOutOfBoundsException if cmd is length 0
502   */
503  public Process exec(String[] cmd) throws IOException
504  {
505    return exec(cmd, null, null);
506  }
507
508  /**
509   * Create a new subprocess with the specified command line, already
510   * tokenized, and specified environment. If the environment is null, the
511   * process inherits the environment of this process. Calls
512   * <code>exec(cmd, env, null)</code>. A security check is performed,
513   * <code>checkExec</code>.
514   *
515   * @param cmd the command to call
516   * @param env the environment to use, in the format name=value
517   * @return the Process object
518   * @throws SecurityException if permission is denied
519   * @throws IOException if an I/O error occurs
520   * @throws NullPointerException if cmd is null, or cmd or env has null
521   *         entries
522   * @throws IndexOutOfBoundsException if cmd is length 0
523   */
524  public Process exec(String[] cmd, String[] env) throws IOException
525  {
526    return exec(cmd, env, null);
527  }
528
529  /**
530   * Create a new subprocess with the specified command line, already
531   * tokenized, and the specified environment and working directory. If the
532   * environment is null, the process inherits the environment of this
533   * process. If the directory is null, the process uses the current working
534   * directory. A security check is performed, <code>checkExec</code>.
535   *
536   * @param cmd the command to call
537   * @param env the environment to use, in the format name=value
538   * @param dir the working directory to use
539   * @return the Process object
540   * @throws SecurityException if permission is denied
541   * @throws IOException if an I/O error occurs
542   * @throws NullPointerException if cmd is null, or cmd or env has null
543   *         entries
544   * @throws IndexOutOfBoundsException if cmd is length 0
545   * @since 1.3
546   */
547  public Process exec(String[] cmd, String[] env, File dir)
548    throws IOException
549  {
550    SecurityManager sm = SecurityManager.current; // Be thread-safe!
551    if (sm != null)
552      sm.checkExec(cmd[0]);
553    return VMRuntime.exec(cmd, env, dir);
554  }
555
556  /**
557   * Returns the number of available processors currently available to the
558   * virtual machine. This number may change over time; so a multi-processor
559   * program want to poll this to determine maximal resource usage.
560   *
561   * @return the number of processors available, at least 1
562   */
563  public int availableProcessors()
564  {
565    return VMRuntime.availableProcessors();
566  }
567
568  /**
569   * Find out how much memory is still free for allocating Objects on the heap.
570   *
571   * @return the number of bytes of free memory for more Objects
572   */
573  public long freeMemory()
574  {
575    return VMRuntime.freeMemory();
576  }
577
578  /**
579   * Find out how much memory total is available on the heap for allocating
580   * Objects.
581   *
582   * @return the total number of bytes of memory for Objects
583   */
584  public long totalMemory()
585  {
586    return VMRuntime.totalMemory();
587  }
588
589  /**
590   * Returns the maximum amount of memory the virtual machine can attempt to
591   * use. This may be <code>Long.MAX_VALUE</code> if there is no inherent
592   * limit (or if you really do have a 8 exabyte memory!).
593   *
594   * @return the maximum number of bytes the virtual machine will attempt
595   *         to allocate
596   */
597  public long maxMemory()
598  {
599    return VMRuntime.maxMemory();
600  }
601
602  /**
603   * Run the garbage collector. This method is more of a suggestion than
604   * anything. All this method guarantees is that the garbage collector will
605   * have "done its best" by the time it returns. Notice that garbage
606   * collection takes place even without calling this method.
607   */
608  public void gc()
609  {
610    VMRuntime.gc();
611  }
612
613  /**
614   * Run finalization on all Objects that are waiting to be finalized. Again,
615   * a suggestion, though a stronger one than {@link #gc()}. This calls the
616   * <code>finalize</code> method of all objects waiting to be collected.
617   *
618   * @see #finalize()
619   */
620  public void runFinalization()
621  {
622    VMRuntime.runFinalization();
623  }
624
625  /**
626   * Tell the VM to trace every bytecode instruction that executes (print out
627   * a trace of it).  No guarantees are made as to where it will be printed,
628   * and the VM is allowed to ignore this request.
629   *
630   * @param on whether to turn instruction tracing on
631   */
632  public void traceInstructions(boolean on)
633  {
634    VMRuntime.traceInstructions(on);
635  }
636
637  /**
638   * Tell the VM to trace every method call that executes (print out a trace
639   * of it).  No guarantees are made as to where it will be printed, and the
640   * VM is allowed to ignore this request.
641   *
642   * @param on whether to turn method tracing on
643   */
644  public void traceMethodCalls(boolean on)
645  {
646    VMRuntime.traceMethodCalls(on);
647  }
648
649  /**
650   * Load a native library using the system-dependent filename. This is similar
651   * to loadLibrary, except the only name mangling done is inserting "_g"
652   * before the final ".so" if the VM was invoked by the name "java_g". There
653   * may be a security check, of <code>checkLink</code>.
654   *
655   * <p>
656   * The library is loaded using the class loader associated with the
657   * class associated with the invoking method.
658   *
659   * @param filename the file to load
660   * @throws SecurityException if permission is denied
661   * @throws UnsatisfiedLinkError if the library is not found
662   */
663  public void load(String filename)
664  {
665    load(filename, VMStackWalker.getCallingClassLoader());
666  }
667
668  /**
669   * Same as <code>load(String)</code> but using the given loader.
670   *
671   * @param filename the file to load
672   * @param loader class loader, or <code>null</code> for the boot loader
673   * @throws SecurityException if permission is denied
674   * @throws UnsatisfiedLinkError if the library is not found
675   */
676  void load(String filename, ClassLoader loader)
677  {
678    SecurityManager sm = SecurityManager.current; // Be thread-safe!
679    if (sm != null)
680      sm.checkLink(filename);
681    if (loadLib(filename, loader) == 0)
682      throw new UnsatisfiedLinkError("Could not load library " + filename);
683  }
684
685  /**
686   * Do a security check on the filename and then load the native library.
687   *
688   * @param filename the file to load
689   * @param loader class loader, or <code>null</code> for the boot loader
690   * @return 0 on failure, nonzero on success
691   * @throws SecurityException if file read permission is denied
692   */
693  private static int loadLib(String filename, ClassLoader loader)
694  {
695    SecurityManager sm = SecurityManager.current; // Be thread-safe!
696    if (sm != null)
697      sm.checkRead(filename);
698    return VMRuntime.nativeLoad(filename, loader);
699  }
700
701  /**
702   * Load a native library using a system-independent "short name" for the
703   * library.  It will be transformed to a correct filename in a
704   * system-dependent manner (for example, in Windows, "mylib" will be turned
705   * into "mylib.dll").  This is done as follows: if the context that called
706   * load has a ClassLoader cl, then <code>cl.findLibrary(libpath)</code> is
707   * used to convert the name. If that result was null, or there was no class
708   * loader, this searches each directory of the system property
709   * <code>java.library.path</code> for a file named
710   * <code>System.mapLibraryName(libname)</code>. There may be a security
711   * check, of <code>checkLink</code>.
712   *
713   * <p>Note: Besides <code>java.library.path</code> a VM may chose to search
714   * for native libraries in a path that is specified by the
715   * <code>gnu.classpath.boot.library.path</code> system property. However
716   * this is for internal usage or development of GNU Classpath only.
717   * <b>A Java application must not load a non-system library by changing
718   * this property otherwise it will break compatibility.</b></p>
719   *
720   * <p>
721   * The library is loaded using the class loader associated with the
722   * class associated with the invoking method.
723   *
724   * @param libname the library to load
725   *
726   * @throws SecurityException if permission is denied
727   * @throws UnsatisfiedLinkError if the library is not found
728   *
729   * @see System#mapLibraryName(String)
730   * @see ClassLoader#findLibrary(String)
731   */
732  public void loadLibrary(String libname)
733  {
734    loadLibrary(libname, VMStackWalker.getCallingClassLoader());
735  }
736
737  /**
738   * Same as <code>loadLibrary(String)</code> but using the given loader.
739   *
740   * @param libname the library to load
741   * @param loader class loader, or <code>null</code> for the boot loader
742   * @throws SecurityException if permission is denied
743   * @throws UnsatisfiedLinkError if the library is not found
744   */
745  void loadLibrary(String libname, ClassLoader loader)
746  {
747    SecurityManager sm = SecurityManager.current; // Be thread-safe!
748    if (sm != null)
749      sm.checkLink(libname);
750    String filename;
751    if (loader != null && (filename = loader.findLibrary(libname)) != null)
752      {
753        if (loadLib(filename, loader) != 0)
754          return;
755      }
756    else
757      {
758        filename = VMRuntime.mapLibraryName(libname);
759        for (int i = 0; i < libpath.length; i++)
760          if (loadLib(libpath[i] + filename, loader) != 0)
761            return;
762      }
763    throw new UnsatisfiedLinkError("Native library `" + libname
764      + "' not found (as file `" + filename + "') in gnu.classpath.boot.library.path and java.library.path");
765  }
766
767  /**
768   * Return a localized version of this InputStream, meaning all characters
769   * are localized before they come out the other end.
770   *
771   * @param in the stream to localize
772   * @return the localized stream
773   * @deprecated <code>InputStreamReader</code> is the preferred way to read
774   *             local encodings
775   * @XXX This implementation does not localize, yet.
776   */
777  public InputStream getLocalizedInputStream(InputStream in)
778  {
779    return in;
780  }
781
782  /**
783   * Return a localized version of this OutputStream, meaning all characters
784   * are localized before they are sent to the other end.
785   *
786   * @param out the stream to localize
787   * @return the localized stream
788   * @deprecated <code>OutputStreamWriter</code> is the preferred way to write
789   *             local encodings
790   * @XXX This implementation does not localize, yet.
791   */
792  public OutputStream getLocalizedOutputStream(OutputStream out)
793  {
794    return out;
795  }
796} // class Runtime