Source for java.io.File

   1: /* File.java -- Class representing a file on disk
   2:    Copyright (C) 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2012
   3:    Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11:  
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: 
  40: package java.io;
  41: 
  42: import java.net.MalformedURLException;
  43: import java.net.URI;
  44: import java.net.URISyntaxException;
  45: import java.net.URL;
  46: import gnu.classpath.Configuration;
  47: 
  48: /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  49:  * "The Java Language Specification", ISBN 0-201-63451-1
  50:  * Status:  Complete to version 1.3.
  51:  */
  52: 
  53: /**
  54:  * This class represents a file or directory on a local disk.  It provides
  55:  * facilities for dealing with a variety of systems that use various
  56:  * types of path separators ("/" versus "\", for example).  It also
  57:  * contains method useful for creating and deleting files and directories.
  58:  *
  59:  * @author Aaron M. Renn (arenn@urbanophile.com)
  60:  * @author Tom Tromey (tromey@cygnus.com)
  61:  */
  62: public class File implements Serializable, Comparable<File>
  63: {
  64:   private static final long serialVersionUID = 301077366599181567L;
  65:     
  66:   // QUERY arguments to access function.
  67:   private final static int READ = 0;
  68:   private final static int WRITE = 1;
  69:   private final static int EXISTS = 2;
  70:   private final static int EXEC = 3;
  71: 
  72:   // QUERY arguments to stat function.
  73:   private final static int DIRECTORY = 0;
  74:   private final static int ISFILE = 1;
  75:   private final static int ISHIDDEN = 2;
  76: 
  77:   // QUERY arguments to attr function.
  78:   private final static int MODIFIED = 0;
  79:   private final static int LENGTH = 1;
  80:   
  81:   private final native long attr (int query);
  82:   private final native boolean access (int query);
  83:   private final native boolean stat (int query);
  84: 
  85:   /**
  86:    * This is the path separator string for the current host. This field
  87:    * contains the value of the <code>file.separator</code> system property.
  88:    * An example separator string would be "/" on the GNU system.
  89:    */
  90:   public static final String separator = System.getProperty("file.separator");
  91:   private static final String dupSeparator = separator + separator;
  92: 
  93:   /**
  94:    * This is the first character of the file separator string.  On many
  95:    * hosts (for example, on the GNU system), this represents the entire 
  96:    * separator string.  The complete separator string is obtained from the
  97:    * <code>file.separator</code>system property.
  98:    */
  99:   public static final char separatorChar = separator.charAt(0);
 100:   
 101:   /**
 102:    * This is the string that is used to separate the host name from the
 103:    * path name in paths that include the host name.  It is the value of
 104:    * the <code>path.separator</code> system property.
 105:    */
 106:   public static final String pathSeparator
 107:     = System.getProperty("path.separator");
 108:   
 109:   /**
 110:    * This is the first character of the string used to separate the host name
 111:    * from the path name in paths that include a host.  The separator string
 112:    * is taken from the <code>path.separator</code> system property.
 113:    */
 114:   public static final char pathSeparatorChar = pathSeparator.charAt(0);
 115: 
 116:   static final String tmpdir = System.getProperty("java.io.tmpdir");
 117:   /* If 0, then the system doesn't have a file name length limit.  */
 118:   static int maxPathLen;
 119:   static boolean caseSensitive;
 120:   
 121:   static
 122:   {
 123:     if (Configuration.INIT_LOAD_LIBRARY)
 124:       {
 125:         System.loadLibrary("javaio");
 126:       }
 127:     
 128:     init_native();
 129:   }
 130:   
 131:   // Native function called at class initialization. This should should
 132:   // set the maxPathLen and caseSensitive variables.
 133:   private static native void init_native();
 134: 
 135:   /**
 136:    * This is the path to the file set when the object is created.  It
 137:    * may be an absolute or relative path name.
 138:    */
 139:   private String path;
 140: 
 141:   // We keep a counter for use by createTempFile.  We choose the first
 142:   // value randomly to try to avoid clashes with other VMs.
 143:   private static long counter = Double.doubleToLongBits (Math.random());
 144: 
 145:   /**
 146:    * This method tests whether or not the current thread is allowed to
 147:    * to read the file pointed to by this object.  This will be true if and
 148:    * and only if 1) the file exists and 2) the <code>SecurityManager</code>
 149:    * (if any) allows access to the file via it's <code>checkRead</code>
 150:    * method 3) the file is readable.
 151:    *
 152:    * @return <code>true</code> if reading is allowed, 
 153:    * <code>false</code> otherwise
 154:    *
 155:    * @exception SecurityException If the <code>SecurityManager</code> 
 156:    * does not allow access to the file
 157:    */
 158:   public boolean canRead()
 159:   {
 160:     checkRead();
 161:     return access (READ);
 162:   }
 163: 
 164:   /**
 165:    * This method test whether or not the current thread is allowed to
 166:    * write to this object.  This will be true if and only if 1) The
 167:    * <code>SecurityManager</code> (if any) allows write access to the
 168:    * file and 2) The file exists and 3) The file is writable.  To determine
 169:    * whether or not a non-existent file can be created, check the parent
 170:    * directory for write access.
 171:    *
 172:    * @return <code>true</code> if writing is allowed, <code>false</code> 
 173:    * otherwise
 174:    *
 175:    * @exception SecurityException If the <code>SecurityManager</code> 
 176:    * does not allow access to the file
 177:    */
 178:   public boolean canWrite()
 179:   {
 180:     checkWrite();
 181:     return access (WRITE);
 182:   }
 183:   
 184:   /**
 185:    * This method tests whether or not the current thread is allowed to
 186:    * to execute the file pointed to by this object. This will be true if and
 187:    * and only if 1) the file exists and 2) the <code>SecurityManager</code>
 188:    * (if any) allows access to the file via it's <code>checkExec</code>
 189:    * method 3) the file is executable.
 190:    *
 191:    * @return <code>true</code> if execution is allowed, 
 192:    * <code>false</code> otherwise
 193:    *
 194:    * @exception SecurityException If the <code>SecurityManager</code> 
 195:    * does not allow access to the file
 196:    */
 197:   public boolean canExecute()
 198:   {
 199:     if (!exists())
 200:       return false;
 201:     checkExec();
 202:     return access (EXEC);
 203:   }
 204: 
 205:   private native boolean performCreate() throws IOException;
 206: 
 207:   /**
 208:    * This method creates a new file of zero length with the same name as
 209:    * the path of this <code>File</code> object if an only if that file
 210:    * does not already exist.
 211:    * <p>
 212:    * A <code>SecurityManager.checkWrite</code> check is done prior
 213:    * to performing this action.
 214:    *
 215:    * @return <code>true</code> if the file was created, <code>false</code> if
 216:    * the file alread existed.
 217:    *
 218:    * @exception IOException If an I/O error occurs
 219:    * @exception SecurityException If the <code>SecurityManager</code> will
 220:    * not allow this operation to be performed.
 221:    *
 222:    * @since 1.2
 223:    */
 224:   public boolean createNewFile() throws IOException
 225:   {
 226:     checkWrite();
 227:     return performCreate();
 228:   }
 229:  
 230:   /*
 231:    * This native method handles the actual deleting of the file
 232:    */
 233:   private native boolean performDelete();
 234: 
 235:   /**
 236:    * This method deletes the file represented by this object.  If this file
 237:    * is a directory, it must be empty in order for the delete to succeed.
 238:    *
 239:    * @return <code>true</code> if the file was deleted, <code>false</code> 
 240:    * otherwise
 241:    *
 242:    * @exception SecurityException If deleting of the file is not allowed
 243:    */
 244:   public synchronized boolean delete()
 245:   {
 246:     SecurityManager s = System.getSecurityManager();
 247:     
 248:     if (s != null)
 249:       s.checkDelete(path);
 250:     
 251:     return performDelete();
 252:   }
 253: 
 254:   /**
 255:    * This method tests two <code>File</code> objects for equality by 
 256:    * comparing the path of the specified <code>File</code> against the path
 257:    * of this object.  The two objects are equal if an only if 1) The
 258:    * argument is not null 2) The argument is a <code>File</code> object and
 259:    * 3) The path of the <code>File</code>argument is equal to the path
 260:    * of this object.
 261:    * <p>
 262:    * The paths of the files are determined by calling the 
 263:    * <code>getPath()</code>
 264:    * method on each object.
 265:    *
 266:    * @return <code>true</code> if the two objects are equal, 
 267:    * <code>false</code> otherwise.
 268:    */
 269:   public boolean equals(Object obj)
 270:   {
 271:     if (! (obj instanceof File))
 272:       return false;
 273:     
 274:     File other = (File) obj;
 275: 
 276:     if (caseSensitive)
 277:       return path.equals(other.path);
 278:     else
 279:       return path.equalsIgnoreCase(other.path);
 280:   }
 281: 
 282:   /*
 283:    * This method tests whether or not the file represented by the
 284:    * object actually exists on the filesystem.
 285:    */
 286:   private boolean internalExists()
 287:   {
 288:     return access (EXISTS);
 289:   }
 290:   
 291:   /**
 292:    * This method tests whether or not the file represented by the object
 293:    * actually exists on the filesystem.
 294:    *
 295:    * @return <code>true</code> if the file exists, <code>false</code>otherwise.
 296:    *
 297:    * @exception SecurityException If reading of the file is not permitted
 298:    */
 299:   public boolean exists()
 300:   {
 301:     checkRead();
 302:     return internalExists();
 303:   }
 304: 
 305:   /**
 306:    * This method initializes a new <code>File</code> object to represent
 307:    * a file with the specified path.
 308:    *
 309:    * @param name The path name of the file
 310:    */
 311:   public File(String name)
 312:   {
 313:     path = normalizePath (name);
 314:   }
 315: 
 316:   // Remove duplicate and redundant separator characters.
 317:   private String normalizePath(String p)
 318:   {
 319:     // On Windows, convert any '/' to '\'.  This appears to be the same logic
 320:     // that Sun's Win32 Java performs.
 321:     if (separatorChar == '\\')
 322:       {
 323:         p = p.replace ('/', '\\');
 324:     // We have to special case the "\c:" prefix.
 325:     if (p.length() > 2 && p.charAt(0) == '\\' &&
 326:         ((p.charAt(1) >= 'a' && p.charAt(1) <= 'z') ||
 327:         (p.charAt(1) >= 'A' && p.charAt(1) <= 'Z')) &&
 328:         p.charAt(2) == ':')
 329:       p = p.substring(1);
 330:       }
 331: 
 332:     int dupIndex = p.indexOf(dupSeparator);
 333:     int plen = p.length();
 334: 
 335:     // Special case: permit Windows UNC path prefix.
 336:     if (dupSeparator.equals("\\\\") && dupIndex == 0)
 337:       dupIndex = p.indexOf(dupSeparator, 1);
 338: 
 339:     if (dupIndex == -1)
 340:       {
 341:         // Ignore trailing separator (though on Windows "a:\", for
 342:         // example, is a valid and minimal path).
 343:         if (plen > 1 && p.charAt (plen - 1) == separatorChar)
 344:       {
 345:         if (! (separatorChar == '\\' && plen == 3 && p.charAt (1) == ':'))
 346:           return p.substring (0, plen - 1);
 347:       }
 348:     else
 349:       return p;
 350:       }
 351:     
 352:     StringBuffer newpath = new StringBuffer(plen);
 353:     int last = 0;
 354:     while (dupIndex != -1)
 355:       {
 356:         newpath.append(p.substring(last, dupIndex));
 357:     // Ignore the duplicate path characters.
 358:     while (p.charAt(dupIndex) == separatorChar)
 359:       {
 360:         dupIndex++;
 361:         if (dupIndex == plen)
 362:           return newpath.toString();
 363:       }
 364:     newpath.append(separatorChar);
 365:     last = dupIndex;
 366:     dupIndex = p.indexOf(dupSeparator, last);
 367:       }
 368:     
 369:     // Again, ignore possible trailing separator (except special cases
 370:     // like "a:\" on Windows).
 371:     int end;
 372:     if (plen > 1 && p.charAt (plen - 1) == separatorChar)
 373:     {
 374:       if (separatorChar == '\\' && plen == 3 && p.charAt (1) == ':')
 375:         end = plen;
 376:       else
 377:         end = plen - 1;
 378:     }
 379:     else
 380:       end = plen;
 381:     newpath.append(p.substring(last, end));
 382:     
 383:     return newpath.toString();
 384:   }
 385:  
 386:   /**
 387:    * This method initializes a new <code>File</code> object to represent
 388:    * a file in the specified named directory.  The path name to the file
 389:    * will be the directory name plus the separator string plus the file
 390:    * name.  If the directory path name ends in the separator string, another
 391:    * separator string will still be appended.
 392:    *
 393:    * @param dirPath The path to the directory the file resides in
 394:    * @param name The name of the file
 395:    */
 396:   public File(String dirPath, String name)
 397:   {
 398:     if (name == null)
 399:       throw new NullPointerException();
 400:     if (dirPath != null)
 401:       {
 402:     if (dirPath.length() > 0)
 403:       {
 404:         // Try to be smart about the number of separator characters.
 405:         if (dirPath.charAt(dirPath.length() - 1) == separatorChar
 406:         || name.length() == 0)
 407:           path = normalizePath(dirPath + name);
 408:         else
 409:           path = normalizePath(dirPath + separatorChar + name);
 410:       }
 411:     else
 412:       {
 413:         // If dirPath is empty, use a system dependant
 414:         // default prefix.
 415:         // Note that the leading separators in name have
 416:         // to be chopped off, to prevent them forming
 417:         // a UNC prefix on Windows.
 418:         if (separatorChar == '\\' /* TODO use ON_WINDOWS */)
 419:           {
 420:         int skip = 0;
 421:         while(name.length() > skip
 422:             && (name.charAt(skip) == separatorChar
 423:             || name.charAt(skip) == '/'))
 424:           {
 425:             skip++;
 426:           }
 427:         name = name.substring(skip);
 428:           }
 429:         path = normalizePath(separatorChar + name);
 430:       }
 431:       }
 432:     else
 433:       path = normalizePath(name);
 434:   }
 435: 
 436:   /**
 437:    * This method initializes a new <code>File</code> object to represent
 438:    * a file in the specified directory.  If the <code>directory</code>
 439:    * argument is <code>null</code>, the file is assumed to be in the
 440:    * current directory as specified by the <code>user.dir</code> system
 441:    * property
 442:    *
 443:    * @param directory The directory this file resides in
 444:    * @param name The name of the file
 445:    */
 446:   public File(File directory, String name)
 447:   {
 448:     this (directory == null ? null : directory.path, name);
 449:   }
 450: 
 451:   /**
 452:    * This method initializes a new <code>File</code> object to represent
 453:    * a file corresponding to the specified <code>file:</code> protocol URI.
 454:    *
 455:    * @param uri The URI
 456:    * @throws IllegalArgumentException if the URI is not hierarchical
 457:    */
 458:   public File(URI uri)
 459:   {
 460:     if (uri == null)
 461:     throw new NullPointerException("uri is null");
 462: 
 463:     if (!uri.getScheme().equals("file"))
 464:     throw new IllegalArgumentException("invalid uri protocol");
 465: 
 466:     String name = uri.getPath();
 467:     if (name == null)
 468:       throw new IllegalArgumentException("URI \"" + uri
 469:                      + "\" is not hierarchical");
 470:     path = normalizePath(name);
 471:   }
 472: 
 473:   /**
 474:    * This method returns the path of this file as an absolute path name.
 475:    * If the path name is already absolute, then it is returned.  Otherwise
 476:    * the value returned is the current directory plus the separatory
 477:    * string plus the path of the file.  The current directory is determined
 478:    * from the <code>user.dir</code> system property.
 479:    *
 480:    * @return The absolute path of this file
 481:    */
 482:   public String getAbsolutePath()
 483:   {
 484:     if (isAbsolute())
 485:       return path;
 486:     else if (separatorChar == '\\' 
 487:              && path.length() > 0 && path.charAt (0) == '\\')
 488:       {
 489:         // On Windows, even if the path starts with a '\\' it is not
 490:         // really absolute until we prefix the drive specifier from
 491:         // the current working directory to it.
 492:         return System.getProperty ("user.dir").substring (0, 2) + path;
 493:       }
 494:     else if (separatorChar == '\\' 
 495:              && path.length() > 1 && path.charAt (1) == ':'
 496:              && ((path.charAt (0) >= 'a' && path.charAt (0) <= 'z')
 497:                  || (path.charAt (0) >= 'A' && path.charAt (0) <= 'Z')))
 498:       {
 499:         // On Windows, a process has a current working directory for
 500:         // each drive and a path like "G:foo\bar" would mean the 
 501:         // absolute path "G:\wombat\foo\bar" if "\wombat" is the 
 502:         // working directory on the G drive.
 503:         String drvDir = null;
 504:         try
 505:           {
 506:             drvDir = new File (path.substring (0, 2)).getCanonicalPath();
 507:           }
 508:         catch (IOException e)
 509:           {
 510:             drvDir = path.substring (0, 2) + "\\";
 511:           }
 512:         
 513:         // Note: this would return "C:\\." for the path "C:.", if "\"
 514:         // is the working folder on the C drive, but this is 
 515:         // consistent with what Sun's JRE 1.4.1.01 actually returns!
 516:         if (path.length() > 2)
 517:           return drvDir + '\\' + path.substring (2, path.length());
 518:         else
 519:           return drvDir;
 520:       }
 521:     else
 522:       return System.getProperty ("user.dir") + separatorChar + path;
 523:   }
 524: 
 525:   /**
 526:    * This method returns a <code>File</code> object representing the
 527:    * absolute path of this object.
 528:    *
 529:    * @return A <code>File</code> with the absolute path of the object.
 530:    *
 531:    * @since 1.2
 532:    */
 533:   public File getAbsoluteFile()
 534:   {
 535:     return new File(getAbsolutePath());
 536:   }
 537: 
 538:   /**
 539:    * This method returns a canonical representation of the pathname of
 540:    * this file.  The actual form of the canonical representation is
 541:    * system-dependent.  On the GNU system, conversion to canonical
 542:    * form involves the removal of redundant separators, references to
 543:    * "." and "..", and symbolic links.
 544:    * <p>
 545:    * Note that this method, unlike the other methods which return path
 546:    * names, can throw an IOException.  This is because native method 
 547:    * might be required in order to resolve the canonical path
 548:    *
 549:    * @exception IOException If an error occurs
 550:    */
 551:   public native String getCanonicalPath() throws IOException;
 552: 
 553:   /**
 554:    * This method returns a <code>File</code> object representing the
 555:    * canonical path of this object.
 556:    *
 557:    * @return A <code>File</code> instance representing the canonical path of
 558:    * this object.
 559:    *
 560:    * @exception IOException If an error occurs.
 561:    *
 562:    * @since 1.2
 563:    */
 564:   public File getCanonicalFile() throws IOException
 565:   {
 566:     return new File(getCanonicalPath());
 567:   }
 568: 
 569:   /**
 570:    * This method returns the name of the file.  This is everything in the
 571:    * complete path of the file after the last instance of the separator
 572:    * string.
 573:    *
 574:    * @return The file name
 575:    */
 576:   public String getName()
 577:   {
 578:     int nameSeqIndex = 0;
 579: 
 580:     if (separatorChar == '\\' && path.length() > 1)
 581:       {
 582:         // On Windows, ignore the drive specifier or the leading '\\'
 583:         // of a UNC network path, if any (a.k.a. the "prefix").
 584:         if ((path.charAt (0) == '\\' && path.charAt (1) == '\\')
 585:             || (((path.charAt (0) >= 'a' && path.charAt (0) <= 'z')
 586:          || (path.charAt (0) >= 'A' && path.charAt (0) <= 'Z'))
 587:         && path.charAt (1) == ':'))
 588:       {
 589:         if (path.length() > 2)
 590:           nameSeqIndex = 2;
 591:         else
 592:           return "";
 593:       }
 594:       }
 595: 
 596:     String nameSeq 
 597:       = (nameSeqIndex > 0 ? path.substring (nameSeqIndex) : path);
 598: 
 599:     int last = nameSeq.lastIndexOf (separatorChar);
 600: 
 601:     return nameSeq.substring (last + 1);
 602:   }
 603: 
 604:   /**
 605:    * This method returns a <code>String</code> the represents this file's
 606:    * parent.  <code>null</code> is returned if the file has no parent.  The
 607:    * parent is determined via a simple operation which removes the name
 608:    * after the last file separator character, as determined by the platform.
 609:    *
 610:    * @return The parent directory of this file
 611:    */
 612:   public String getParent()
 613:   {
 614:     String prefix = null;
 615:     int nameSeqIndex = 0;
 616: 
 617:     // The "prefix", if present, is the leading "/" on UNIX and 
 618:     // either the drive specifier (e.g. "C:") or the leading "\\"
 619:     // of a UNC network path on Windows.
 620:     if (separatorChar == '/' && path.charAt (0) == '/')
 621:       {
 622:         prefix = "/";
 623:         nameSeqIndex = 1;
 624:       }
 625:     else if (separatorChar == '\\' && path.length() > 1)
 626:       {
 627:         if ((path.charAt (0) == '\\' && path.charAt (1) == '\\')
 628:             || (((path.charAt (0) >= 'a' && path.charAt (0) <= 'z')
 629:                  || (path.charAt (0) >= 'A' && path.charAt (0) <= 'Z'))
 630:                 && path.charAt (1) == ':'))
 631:           {
 632:             prefix = path.substring (0, 2);
 633:             nameSeqIndex = 2;
 634:           }
 635:       }
 636: 
 637:     // According to the JDK docs, the returned parent path is the 
 638:     // portion of the name sequence before the last separator
 639:     // character, if found, prefixed by the prefix, otherwise null.
 640:     if (nameSeqIndex < path.length())
 641:       {
 642:         String nameSeq = path.substring (nameSeqIndex, path.length());
 643:         int last = nameSeq.lastIndexOf (separatorChar);
 644:         if (last == -1)
 645:           return prefix;
 646:         else if (last == (nameSeq.length() - 1))
 647:           // Note: The path would not have a trailing separator
 648:           // except for cases like "C:\" on Windows (see 
 649:           // normalizePath( )), where Sun's JRE 1.4 returns null.
 650:           return null;
 651:         else if (last == 0)
 652:           last++;
 653: 
 654:         if (prefix != null)
 655:           return prefix + nameSeq.substring (0, last);
 656:         else
 657:           return nameSeq.substring (0, last);
 658:       }
 659:     else
 660:       // Sun's JRE 1.4 returns null if the prefix is the only 
 661:       // component of the path - so "/" gives null on UNIX and 
 662:       // "C:", "\\", etc. return null on Windows.
 663:       return null;
 664:   }
 665: 
 666:   /**
 667:    * This method returns a <code>File</code> object representing the parent
 668:    * file of this one.
 669:    *
 670:    * @return a <code>File</code> for the parent of this object.  
 671:    * <code>null</code>
 672:    * will be returned if this object does not have a parent.
 673:    *
 674:    * @since 1.2
 675:    */
 676:   public File getParentFile()
 677:   {
 678:     String parent = getParent();
 679:     return parent != null ? new File(parent) : null;
 680:   }
 681: 
 682:   /**
 683:    * Returns the path name that represents this file.  May be a relative
 684:    * or an absolute path name
 685:    *
 686:    * @return The pathname of this file
 687:    */
 688:   public String getPath()
 689:   {
 690:     return path;
 691:   }
 692: 
 693:   /**
 694:    * This method returns a hash code representing this file.  It is the
 695:    * hash code of the path of this file (as returned by <code>getPath()</code>)
 696:    * exclusived or-ed with the value 1234321.
 697:    *
 698:    * @return The hash code for this object
 699:    */
 700:   public int hashCode()
 701:   {
 702:     if (caseSensitive)
 703:       return path.hashCode() ^ 1234321;
 704:     else
 705:       return path.toLowerCase().hashCode() ^ 1234321;
 706:   }
 707: 
 708:   /**
 709:    * This method returns true if this object represents an absolute file
 710:    * path and false if it does not.  The definition of an absolute path varies
 711:    * by system.  As an example, on GNU systems, a path is absolute if it starts
 712:    * with a "/".
 713:    *
 714:    * @return <code>true</code> if this object represents an absolute 
 715:    * file name, <code>false</code> otherwise.
 716:    */
 717:   public native boolean isAbsolute();
 718: 
 719:   /*
 720:    * This method tests whether or not the file represented by this
 721:    * object is a directory.
 722:    */
 723:   private boolean internalIsDirectory()
 724:   {
 725:     return stat (DIRECTORY);
 726:   }
 727:   
 728:   /**
 729:    * This method tests whether or not the file represented by this object
 730:    * is a directory.  In order for this method to return <code>true</code>,
 731:    * the file represented by this object must exist and be a directory.
 732:    * 
 733:    * @return <code>true</code> if this file is a directory, <code>false</code>
 734:    * otherwise
 735:    *
 736:    * @exception SecurityException If reading of the file is not permitted
 737:    */
 738:   public boolean isDirectory()
 739:   {
 740:     checkRead();
 741:     return internalIsDirectory();
 742:   }
 743: 
 744:   /**
 745:    * This method tests whether or not the file represented by this object
 746:    * is a "plain" file.  A file is a plain file if and only if it 1) Exists,
 747:    * 2) Is not a directory or other type of special file.
 748:    *
 749:    * @return <code>true</code> if this is a plain file, <code>false</code> 
 750:    * otherwise
 751:    *
 752:    * @exception SecurityException If reading of the file is not permitted
 753:    */
 754:   public boolean isFile()
 755:   {
 756:     checkRead();
 757:     return stat (ISFILE);
 758:   }
 759: 
 760:   /**
 761:    * This method tests whether or not this file represents a "hidden" file.
 762:    * On GNU systems, a file is hidden if its name begins with a "."
 763:    * character.  Files with these names are traditionally not shown with
 764:    * directory listing tools.
 765:    *
 766:    * @return <code>true</code> if the file is hidden, <code>false</code>
 767:    * otherwise.
 768:    *
 769:    * @since 1.2
 770:    */
 771:   public boolean isHidden()
 772:   {
 773:     checkRead();
 774:     return stat (ISHIDDEN);
 775:   }
 776: 
 777:   /**
 778:    * This method returns the last modification time of this file.  The
 779:    * time value returned is an abstract value that should not be interpreted
 780:    * as a specified time value.  It is only useful for comparing to other
 781:    * such time values returned on the same system.  In that case, the larger
 782:    * value indicates a more recent modification time. 
 783:    * <p>
 784:    * If the file does not exist, then a value of 0 is returned.
 785:    *
 786:    * @return The last modification time of the file
 787:    *
 788:    * @exception SecurityException If reading of the file is not permitted
 789:    */
 790:   public long lastModified()
 791:   {
 792:     checkRead();
 793:     return attr (MODIFIED);
 794:   }
 795: 
 796:   /**
 797:    * This method returns the length of the file represented by this object,
 798:    * or 0 if the specified file does not exist.
 799:    *
 800:    * @return The length of the file
 801:    *
 802:    * @exception SecurityException If reading of the file is not permitted
 803:    */
 804:   public long length()
 805:   {
 806:     checkRead();
 807:     return attr (LENGTH);
 808:   }
 809: 
 810:   /*
 811:    * This native function actually produces the list of file in this
 812:    * directory
 813:    */
 814:   private final native Object[] performList (FilenameFilter filter,
 815:                          FileFilter fileFilter,
 816:                          Class result_type);
 817: 
 818:   /**
 819:    * This method returns a array of <code>String</code>'s representing the
 820:    * list of files is then directory represented by this object.  If this
 821:    * object represents a non-directory file or a non-existent file, then
 822:    * <code>null</code> is returned.  The list of files will not contain
 823:    * any names such as "." or ".." which indicate the current or parent
 824:    * directory.  Also, the names are not guaranteed to be sorted.
 825:    * <p>
 826:    * In this form of the <code>list()</code> method, a filter is specified
 827:    * that allows the caller to control which files are returned in the
 828:    * list.  The <code>FilenameFilter</code> specified is called for each
 829:    * file returned to determine whether or not that file should be included
 830:    * in the list.
 831:    * <p>
 832:    * A <code>SecurityManager</code> check is made prior to reading the
 833:    * directory.  If read access to the directory is denied, an exception
 834:    * will be thrown.
 835:    *
 836:    * @param filter An object which will identify files to exclude from 
 837:    * the directory listing.
 838:    *
 839:    * @return An array of files in the directory, or <code>null</code> 
 840:    * if this object does not represent a valid directory.
 841:    * 
 842:    * @exception SecurityException If read access is not allowed to the 
 843:    * directory by the <code>SecurityManager</code>
 844:    */
 845:   public String[] list(FilenameFilter filter)
 846:   {
 847:     checkRead();
 848:     return (String[]) performList (filter, null, String.class);
 849:   }
 850: 
 851:   /**
 852:    * This method returns a array of <code>String</code>'s representing the
 853:    * list of files is then directory represented by this object.  If this
 854:    * object represents a non-directory file or a non-existent file, then
 855:    * <code>null</code> is returned.  The list of files will not contain
 856:    * any names such as "." or ".." which indicate the current or parent
 857:    * directory.  Also, the names are not guaranteed to be sorted.
 858:    * <p>
 859:    * A <code>SecurityManager</code> check is made prior to reading the
 860:    * directory.  If read access to the directory is denied, an exception
 861:    * will be thrown.
 862:    *
 863:    * @return An array of files in the directory, or <code>null</code> if 
 864:    * this object does not represent a valid directory.
 865:    * 
 866:    * @exception SecurityException If read access is not allowed to the 
 867:    * directory by the <code>SecurityManager</code>
 868:    */
 869:   public String[] list()
 870:   {
 871:     checkRead();
 872:     return (String[]) performList (null, null, String.class);
 873:   }
 874: 
 875:   /**
 876:    * This method returns an array of <code>File</code> objects representing
 877:    * all the files in the directory represented by this object. If this
 878:    * object does not represent a directory, <code>null</code> is returned.
 879:    * Each of the returned <code>File</code> object is constructed with this
 880:    * object as its parent.
 881:    * <p>
 882:    * A <code>SecurityManager</code> check is made prior to reading the
 883:    * directory.  If read access to the directory is denied, an exception
 884:    * will be thrown.
 885:    *
 886:    * @return An array of <code>File</code> objects for this directory.
 887:    *
 888:    * @exception SecurityException If the <code>SecurityManager</code> denies
 889:    * access to this directory.
 890:    *
 891:    * @since 1.2
 892:    */
 893:   public File[] listFiles()
 894:   {
 895:     checkRead();
 896:     return (File[]) performList (null, null, File.class);
 897:   }
 898:   
 899:   /**
 900:    * This method returns an array of <code>File</code> objects representing
 901:    * all the files in the directory represented by this object. If this
 902:    * object does not represent a directory, <code>null</code> is returned.
 903:    * Each of the returned <code>File</code> object is constructed with this
 904:    * object as its parent.
 905:    * <p> 
 906:    * In this form of the <code>listFiles()</code> method, a filter is specified
 907:    * that allows the caller to control which files are returned in the
 908:    * list.  The <code>FilenameFilter</code> specified is called for each
 909:    * file returned to determine whether or not that file should be included
 910:    * in the list.
 911:    * <p>
 912:    * A <code>SecurityManager</code> check is made prior to reading the
 913:    * directory.  If read access to the directory is denied, an exception
 914:    * will be thrown.
 915:    *
 916:    * @return An array of <code>File</code> objects for this directory.
 917:    *
 918:    * @exception SecurityException If the <code>SecurityManager</code> denies
 919:    * access to this directory.
 920:    *
 921:    * @since 1.2
 922:    */
 923:   public File[] listFiles(FilenameFilter filter)
 924:   {
 925:     checkRead();
 926:     return (File[]) performList (filter, null, File.class);
 927:   }
 928: 
 929:   /**
 930:    * This method returns an array of <code>File</code> objects representing
 931:    * all the files in the directory represented by this object. If this
 932:    * object does not represent a directory, <code>null</code> is returned.
 933:    * Each of the returned <code>File</code> object is constructed with this
 934:    * object as its parent.
 935:    * <p> 
 936:    * In this form of the <code>listFiles()</code> method, a filter is specified
 937:    * that allows the caller to control which files are returned in the
 938:    * list.  The <code>FileFilter</code> specified is called for each
 939:    * file returned to determine whether or not that file should be included
 940:    * in the list.
 941:    * <p>
 942:    * A <code>SecurityManager</code> check is made prior to reading the
 943:    * directory.  If read access to the directory is denied, an exception
 944:    * will be thrown.
 945:    *
 946:    * @return An array of <code>File</code> objects for this directory.
 947:    *
 948:    * @exception SecurityException If the <code>SecurityManager</code> denies
 949:    * access to this directory.
 950:    *
 951:    * @since 1.2
 952:    */
 953:   public File[] listFiles(FileFilter filter)
 954:   {
 955:     checkRead();
 956:     return (File[]) performList (null, filter, File.class);
 957:   }
 958: 
 959:   /**
 960:    * This method returns a <code>String</code> that is the path name of the
 961:    * file as returned by <code>getPath</code>.
 962:    *
 963:    * @return A <code>String</code> representation of this file
 964:    */
 965:   public String toString()
 966:   {
 967:     return path;
 968:   }
 969: 
 970:   /**
 971:    * @return A <code>URI</code> for this object.
 972:    */
 973:   public URI toURI()
 974:   {
 975:     String abspath = getAbsolutePath();
 976: 
 977:     if (isDirectory())
 978:       abspath = abspath + separator;
 979:         
 980:     try
 981:       {
 982:     return new URI("file", abspath.replace(separatorChar, '/'), null);
 983:       }
 984:     catch (URISyntaxException use)
 985:       {
 986:         // Can't happen.
 987:     throw new RuntimeException(use);
 988:       }
 989:   }
 990: 
 991:   /**
 992:    * This method returns a <code>URL</code> with the <code>file:</code>
 993:    * protocol that represents this file.  The exact form of this URL is
 994:    * system dependent.
 995:    *
 996:    * @return A <code>URL</code> for this object.
 997:    *
 998:    * @exception MalformedURLException If the URL cannot be created 
 999:    * successfully.
1000:    */
1001:   public URL toURL() throws MalformedURLException
1002:   {
1003:     // On Win32, Sun's JDK returns URLs of the form "file:/c:/foo/bar.txt",
1004:     // while on UNIX, it returns URLs of the form "file:/foo/bar.txt". 
1005:     if (separatorChar == '\\')
1006:       return new URL ("file:/" + getAbsolutePath().replace ('\\', '/')
1007:               + (isDirectory() ? "/" : ""));
1008:     else
1009:       return new URL ("file:" + getAbsolutePath()
1010:               + (isDirectory() ? "/" : ""));
1011:   }
1012: 
1013:   /*
1014:    * This native method actually creates the directory
1015:    */
1016:   private final native boolean performMkdir();
1017: 
1018:   /**
1019:    * This method creates a directory for the path represented by this object.
1020:    *
1021:    * @return <code>true</code> if the directory was created, 
1022:    * <code>false</code> otherwise
1023:    *
1024:    * @exception SecurityException If write access is not allowed to this file
1025:    */
1026:   public boolean mkdir()
1027:   {
1028:     checkWrite();
1029:     return performMkdir();
1030:   }
1031: 
1032:   private static boolean mkdirs (File x)
1033:   {
1034:     if (x.isDirectory())
1035:       return true;
1036:     String p = x.getPath();
1037:     String parent = x.getParent();
1038:     if (parent != null)
1039:       {
1040:     x.path = parent;
1041:     if (! mkdirs (x))
1042:       return false;
1043:     x.path = p;
1044:       }
1045:     return x.mkdir();
1046:   }
1047: 
1048:   /**
1049:    * This method creates a directory for the path represented by this file.
1050:    * It will also create any intervening parent directories if necessary.
1051:    *
1052:    * @return <code>true</code> if the directory was created, 
1053:    * <code>false</code> otherwise
1054:    *
1055:    * @exception SecurityException If write access is not allowed to this file
1056:    */
1057:   public boolean mkdirs()
1058:   {
1059:     checkWrite();
1060:     if (isDirectory())
1061:       return false;
1062:     return mkdirs (new File (path));
1063:   }
1064: 
1065:   private static synchronized String nextValue()
1066:   {
1067:     return Long.toString(counter++, Character.MAX_RADIX);
1068:   }
1069: 
1070:   /**
1071:    * This method creates a temporary file in the specified directory.  If 
1072:    * the directory name is null, then this method uses the system temporary 
1073:    * directory. The files created are guaranteed not to currently exist and 
1074:    * the same file name will never be used twice in the same virtual 
1075:    * machine instance.  
1076:    * The system temporary directory is determined by examinging the 
1077:    * <code>java.io.tmpdir</code> system property.
1078:    * <p>
1079:    * The <code>prefix</code> parameter is a sequence of at least three
1080:    * characters that are used as the start of the generated filename.  The
1081:    * <code>suffix</code> parameter is a sequence of characters that is used
1082:    * to terminate the file name.  This parameter may be <code>null</code>
1083:    * and if it is, the suffix defaults to ".tmp".
1084:    * <p>
1085:    * If a <code>SecurityManager</code> exists, then its <code>checkWrite</code>
1086:    * method is used to verify that this operation is permitted.
1087:    *
1088:    * @param prefix The character prefix to use in generating the path name.
1089:    * @param suffix The character suffix to use in generating the path name.
1090:    * @param directory The directory to create the file in, or 
1091:    * <code>null</code> for the default temporary directory
1092:    *
1093:    * @exception IllegalArgumentException If the patterns is not valid
1094:    * @exception SecurityException If there is no permission to perform 
1095:    * this operation
1096:    * @exception IOException If an error occurs
1097:    *
1098:    * @since 1.2
1099:    */
1100:   public static File createTempFile(String prefix, String suffix,
1101:                     File directory)
1102:     throws IOException
1103:   {
1104:     // Grab the system temp directory if necessary
1105:     if (directory == null)
1106:       {
1107:         String dirname = tmpdir;
1108:         if (dirname == null)
1109:           throw new IOException("Cannot determine system temporary directory"); 
1110:     
1111:         directory = new File(dirname);
1112:         if (!directory.internalExists())
1113:           throw new IOException("System temporary directory "
1114:                                 + directory.getName() + " does not exist.");
1115:         if (!directory.internalIsDirectory())
1116:           throw new IOException("System temporary directory "
1117:                                 + directory.getName()
1118:                                 + " is not really a directory.");
1119:       }
1120: 
1121:     // Check if prefix is at least 3 characters long
1122:     if (prefix.length() < 3)
1123:       throw new IllegalArgumentException("Prefix too short: " + prefix);
1124: 
1125:     // Set default value of suffix
1126:     if (suffix == null)
1127:       suffix = ".tmp";
1128: 
1129:     // Truncation rules.
1130:     // `6' is the number of characters we generate.
1131:     // If maxPathLen equals zero, then the system doesn't have a limit
1132:     // on the file name, so there is nothing to truncate.
1133:     if (maxPathLen > 0 && prefix.length() + 6 + suffix.length() > maxPathLen)
1134:       {
1135:     int suf_len = 0;
1136:     if (suffix.charAt(0) == '.')
1137:       suf_len = 4;
1138:     suffix = suffix.substring(0, suf_len);
1139:     if (prefix.length() + 6 + suf_len > maxPathLen)
1140:       prefix = prefix.substring(0, maxPathLen - 6 - suf_len);
1141:       }
1142: 
1143:     File f;
1144: 
1145:     // How many times should we try?  We choose 100.
1146:     for (int i = 0; i < 100; ++i)
1147:       {
1148:     // This is ugly.
1149:     String t = "ZZZZZZ" + nextValue();
1150:     String l = prefix + t.substring(t.length() - 6) + suffix;
1151:     try
1152:       {
1153:         f = new File(directory, l);
1154:         if (f.createNewFile())
1155:           return f;
1156:       }
1157:     catch (IOException ignored)
1158:       {
1159:       }
1160:       }
1161: 
1162:     throw new IOException ("cannot create temporary file");
1163:   }
1164: 
1165:   /*
1166:    * This native method sets file permissions.
1167:    */
1168:   private native boolean setFilePermissions(boolean enable, boolean ownerOnly,
1169:                         int permissions);
1170: 
1171:   /**
1172:    * This method sets the owner's read permission for the File represented by
1173:    * this object.
1174:    * 
1175:    * It is the same as calling <code>setReadable(readable, true)</code>.
1176:    * 
1177:    * @param <code>readable</code> <code>true</code> to set read permission,
1178:    * <code>false</code> to unset the read permission.
1179:    * @return <code>true</code> if the file permissions are changed,
1180:    * <code>false</code> otherwise.
1181:    * @exception SecurityException If write access of the file is not permitted.
1182:    * @see #setReadable(boolean, boolean)
1183:    * @since 1.6
1184:    */
1185:   public boolean setReadable(boolean readable)
1186:   {
1187:     return setReadable(readable, true);
1188:   }
1189:   
1190:   /**
1191:    * This method sets the read permissions for the File represented by
1192:    * this object.
1193:    * 
1194:    * If <code>ownerOnly</code> is set to <code>true</code> then only the
1195:    * read permission bit for the owner of the file is changed.
1196:    * 
1197:    * If <code>ownerOnly</code> is set to <code>false</code>, the file
1198:    * permissions are changed so that the file can be read by everyone.
1199:    * 
1200:    * On unix like systems this sets the <code>user</code>, <code>group</code>
1201:    * and <code>other</code> read bits and is equal to call
1202:    * <code>chmod a+r</code> on the file.
1203:    * 
1204:    * @param <code>readable</code> <code>true</code> to set read permission,
1205:    * <code>false</code> to unset the read permission.
1206:    * @param <code>ownerOnly</code> <code>true</code> to set read permission
1207:    * for owner only, <code>false</code> for all.
1208:    * @return <code>true</code> if the file permissions are changed,
1209:    * <code>false</code> otherwise.
1210:    * @exception SecurityException If write access of the file is not permitted.
1211:    * @see #setReadable(boolean)
1212:    * @since 1.6
1213:    */
1214:   public boolean setReadable(boolean readable, boolean ownerOnly)
1215:   {
1216:     checkWrite();
1217:     return setFilePermissions(readable, ownerOnly, READ);
1218:   }
1219:   
1220:   /**
1221:    * This method sets the owner's write permission for the File represented by
1222:    * this object.
1223:    * 
1224:    * It is the same as calling <code>setWritable(readable, true)</code>. 
1225:    * 
1226:    * @param <code>writable</code> <code>true</code> to set write permission,
1227:    * <code>false</code> to unset write permission.
1228:    * @return <code>true</code> if the file permissions are changed,
1229:    * <code>false</code> otherwise.
1230:    * @exception SecurityException If write access of the file is not permitted.
1231:    * @see #setWritable(boolean, boolean)
1232:    * @since 1.6
1233:    */
1234:   public boolean setWritable(boolean writable)
1235:   {
1236:     return setWritable(writable, true);
1237:   }
1238:   
1239:   /**
1240:    * This method sets the write permissions for the File represented by
1241:    * this object.
1242:    * 
1243:    * If <code>ownerOnly</code> is set to <code>true</code> then only the
1244:    * write permission bit for the owner of the file is changed.
1245:    * 
1246:    * If <code>ownerOnly</code> is set to <code>false</code>, the file
1247:    * permissions are changed so that the file can be written by everyone.
1248:    * 
1249:    * On unix like systems this set the <code>user</code>, <code>group</code>
1250:    * and <code>other</code> write bits and is equal to call
1251:    * <code>chmod a+w</code> on the file.
1252:    * 
1253:    * @param <code>writable</code> <code>true</code> to set write permission,
1254:    * <code>false</code> to unset write permission.
1255:    * @param <code>ownerOnly</code> <code>true</code> to set write permission
1256:    * for owner only, <code>false</code> for all. 
1257:    * @return <code>true</code> if the file permissions are changed,
1258:    * <code>false</code> otherwise.
1259:    * @exception SecurityException If write access of the file is not permitted.
1260:    * @see #setWritable(boolean)
1261:    * @since 1.6
1262:    */
1263:   public boolean setWritable(boolean writable, boolean ownerOnly)
1264:   {
1265:     checkWrite();
1266:     return setFilePermissions(writable, ownerOnly, WRITE);
1267:   }
1268:   
1269:   /**
1270:    * This method sets the owner's execute permission for the File represented
1271:    * by this object.
1272:    * 
1273:    * It is the same as calling <code>setExecutable(readable, true)</code>. 
1274:    * 
1275:    * @param <code>executable</code> <code>true</code> to set execute permission,
1276:    * <code>false</code> to unset execute permission.
1277:    * @return <code>true</code> if the file permissions are changed,
1278:    * <code>false</code> otherwise.
1279:    * @exception SecurityException If write access of the file is not permitted.
1280:    * @see #setExecutable(boolean, boolean)
1281:    * @since 1.6
1282:    */
1283:   public boolean setExecutable(boolean executable) 
1284:   {
1285:     return setExecutable(executable, true);
1286:   }
1287:   
1288:   /**
1289:    * This method sets the execute permissions for the File represented by
1290:    * this object.
1291:    * 
1292:    * If <code>ownerOnly</code> is set to <code>true</code> then only the
1293:    * execute permission bit for the owner of the file is changed.
1294:    * 
1295:    * If <code>ownerOnly</code> is set to <code>false</code>, the file
1296:    * permissions are changed so that the file can be executed by everyone.
1297:    * 
1298:    * On unix like systems this set the <code>user</code>, <code>group</code>
1299:    * and <code>other</code> write bits and is equal to call
1300:    * <code>chmod a+x</code> on the file.
1301:    * 
1302:    * @param <code>executable</code> <code>true</code> to set write permission,
1303:    * <code>false</code> to unset write permission.
1304:    * @param <code>ownerOnly</code> <code>true</code> to set write permission
1305:    * for owner only, <code>false</code> for all. 
1306:    * @return <code>true</code> if the file permissions are changed,
1307:    * <code>false</code> otherwise.
1308:    * @exception SecurityException If write access of the file is not permitted.
1309:    * @see #setExecutable(boolean)
1310:    * @since 1.6
1311:    */
1312:   public boolean setExecutable(boolean executable, boolean ownerOnly)
1313:   {
1314:     checkWrite();
1315:     return setFilePermissions(executable, ownerOnly, EXEC);
1316:   }
1317: 
1318:   /*
1319:    * This native method sets the permissions to make the file read only.
1320:    */
1321:   private native boolean performSetReadOnly();
1322: 
1323:   /**
1324:    * This method sets the file represented by this object to be read only.
1325:    * A read only file or directory cannot be modified.  Please note that 
1326:    * GNU systems allow read only files to be deleted if the directory it
1327:    * is contained in is writable.
1328:    *
1329:    * @return <code>true</code> if the operation succeeded, <code>false</code>
1330:    * otherwise.
1331:    *
1332:    * @exception SecurityException If the <code>SecurityManager</code> does
1333:    * not allow this operation.
1334:    *
1335:    * @since 1.2
1336:    */
1337:   public boolean setReadOnly()
1338:   {
1339:     // Do a security check before trying to do anything else.
1340:     checkWrite();
1341:     return performSetReadOnly();
1342:   }
1343: 
1344:   private static native File[] performListRoots();
1345: 
1346:   /**
1347:    * This method returns an array of filesystem roots.  Some operating systems
1348:    * have volume oriented filesystem.  This method provides a mechanism for
1349:    * determining which volumes exist.  GNU systems use a single hierarchical
1350:    * filesystem, so will have only one "/" filesystem root.
1351:    *
1352:    * @return An array of <code>File</code> objects for each filesystem root
1353:    * available.
1354:    *
1355:    * @since 1.2
1356:    */
1357:   public static File[] listRoots()
1358:   {
1359:     File[] roots = performListRoots();
1360:     
1361:     SecurityManager s = System.getSecurityManager();
1362:     if (s != null)
1363:       {
1364:     // Only return roots to which the security manager permits read access.
1365:     int count = roots.length;
1366:     for (int i = 0; i < roots.length; i++)
1367:       {
1368:         try
1369:           {
1370:             s.checkRead (roots[i].path);        
1371:           }
1372:         catch (SecurityException sx)
1373:           {
1374:             roots[i] = null;
1375:         count--;
1376:           }
1377:       }
1378:     if (count != roots.length)
1379:       {
1380:         File[] newRoots = new File[count];
1381:         int k = 0;
1382:         for (int i=0; i < roots.length; i++)
1383:           {
1384:             if (roots[i] != null)
1385:           newRoots[k++] = roots[i];
1386:           }
1387:         roots = newRoots;
1388:       }
1389:       }
1390:     return roots;
1391:   }
1392: 
1393:   /**
1394:    * This method creates a temporary file in the system temporary directory. 
1395:    * The files created are guaranteed not to currently exist and the same file
1396:    * name will never be used twice in the same virtual machine instance.  The
1397:    * system temporary directory is determined by examinging the 
1398:    * <code>java.io.tmpdir</code> system property.
1399:    * <p>
1400:    * The <code>prefix</code> parameter is a sequence of at least three
1401:    * characters that are used as the start of the generated filename.  The
1402:    * <code>suffix</code> parameter is a sequence of characters that is used
1403:    * to terminate the file name.  This parameter may be <code>null</code>
1404:    * and if it is, the suffix defaults to ".tmp".
1405:    * <p>
1406:    * If a <code>SecurityManager</code> exists, then its <code>checkWrite</code>
1407:    * method is used to verify that this operation is permitted.
1408:    * <p>
1409:    * This method is identical to calling 
1410:    * <code>createTempFile(prefix, suffix, null)</code>.
1411:    *
1412:    * @param prefix The character prefix to use in generating the path name.
1413:    * @param suffix The character suffix to use in generating the path name.
1414:    *
1415:    * @exception IllegalArgumentException If the prefix or suffix are not valid.
1416:    * @exception SecurityException If there is no permission to perform 
1417:    * this operation
1418:    * @exception IOException If an error occurs
1419:    */
1420:   public static File createTempFile(String prefix, String suffix)
1421:     throws IOException
1422:   {
1423:     return createTempFile(prefix, suffix, null);
1424:   }
1425: 
1426:   /**
1427:    * This method compares the specified <code>File</code> to this one
1428:    * to test for equality.  It does this by comparing the canonical path names
1429:    * of the files. 
1430:    * <p>
1431:    * The canonical paths of the files are determined by calling the
1432:    * <code>getCanonicalPath</code> method on each object.
1433:    * <p>
1434:    * This method returns a 0 if the specified <code>Object</code> is equal
1435:    * to this one, a negative value if it is less than this one 
1436:    * a positive value if it is greater than this one.
1437:    *
1438:    * @return An integer as described above
1439:    *
1440:    * @since 1.2
1441:    */
1442:   public int compareTo(File other)
1443:   {
1444:     if (caseSensitive)
1445:       return path.compareTo (other.path);
1446:     else
1447:       return path.compareToIgnoreCase (other.path);
1448:   }
1449: 
1450:   /*
1451:    * This native method actually performs the rename.
1452:    */
1453:   private native boolean performRenameTo (File dest);
1454: 
1455:   /**
1456:    * This method renames the file represented by this object to the path
1457:    * of the file represented by the argument <code>File</code>.
1458:    *
1459:    * @param dest The <code>File</code> object representing the target name
1460:    *
1461:    * @return <code>true</code> if the rename succeeds, <code>false</code> 
1462:    * otherwise.
1463:    *
1464:    * @exception SecurityException If write access is not allowed to the 
1465:    * file by the <code>SecurityMananger</code>.
1466:    */
1467:   public synchronized boolean renameTo(File dest)
1468:   {
1469:     SecurityManager s = System.getSecurityManager();
1470:     if (s != null)
1471:       {
1472:     s.checkWrite (getPath());
1473:     s.checkWrite (dest.getPath());
1474:       }
1475:     return performRenameTo (dest);
1476:   }
1477: 
1478:   /*
1479:    * This method does the actual setting of the modification time.
1480:    */
1481:   private native boolean performSetLastModified(long time);
1482:  
1483:   /**
1484:    * This method sets the modification time on the file to the specified
1485:    * value.  This is specified as the number of seconds since midnight
1486:    * on January 1, 1970 GMT.
1487:    *
1488:    * @param time The desired modification time.
1489:    *
1490:    * @return <code>true</code> if the operation succeeded, <code>false</code>
1491:    * otherwise.
1492:    *
1493:    * @exception IllegalArgumentException If the specified time is negative.
1494:    * @exception SecurityException If the <code>SecurityManager</code> will
1495:    * not allow this operation.
1496:    *
1497:    * @since 1.2
1498:    */
1499:   public boolean setLastModified(long time) 
1500:   {
1501:     if (time < 0)
1502:       throw new IllegalArgumentException("Negative modification time: " + time);
1503: 
1504:     checkWrite();
1505:     return performSetLastModified(time);
1506:   }
1507: 
1508:   private void checkWrite()
1509:   {
1510:     // Check the SecurityManager
1511:     SecurityManager s = System.getSecurityManager();
1512:     
1513:     if (s != null)
1514:       s.checkWrite(path);
1515:   }
1516: 
1517:   private void checkRead()
1518:   {
1519:     // Check the SecurityManager
1520:     SecurityManager s = System.getSecurityManager();
1521:     
1522:     if (s != null)
1523:       s.checkRead(path);
1524:   }
1525: 
1526:   private void checkExec()
1527:   {
1528:     // Check the SecurityManager
1529:     SecurityManager s = System.getSecurityManager();
1530:     
1531:     if (s != null)
1532:       s.checkExec(path);
1533:   }
1534: 
1535:   /** 
1536:    * Calling this method requests that the file represented by this object
1537:    * be deleted when the virtual machine exits.  Note that this request cannot
1538:    * be cancelled.  Also, it will only be carried out if the virtual machine
1539:    * exits normally.
1540:    *
1541:    * @exception SecurityException If deleting of the file is not allowed
1542:    *
1543:    * @since 1.2 
1544:    */
1545:   // FIXME: This should use the ShutdownHook API once we implement that.
1546:   public void deleteOnExit()
1547:   {
1548:     // Check the SecurityManager
1549:     SecurityManager sm = System.getSecurityManager();
1550:     if (sm != null)
1551:       sm.checkDelete (getPath());
1552: 
1553:     DeleteFileHelper.add(this);
1554:   }
1555: 
1556:   private void writeObject(ObjectOutputStream oos) throws IOException
1557:   {
1558:     oos.defaultWriteObject();
1559:     oos.writeChar(separatorChar);
1560:   }
1561: 
1562:   private void readObject(ObjectInputStream ois)
1563:     throws ClassNotFoundException, IOException
1564:   {
1565:     ois.defaultReadObject();
1566: 
1567:     // If the file was from an OS with a different dir separator,
1568:     // fixup the path to use the separator on this OS.
1569:     char oldSeparatorChar = ois.readChar();
1570:     
1571:     if (oldSeparatorChar != separatorChar)
1572:       path = path.replace(oldSeparatorChar, separatorChar);
1573:   }
1574:   
1575: } // class File