1 /*
2 * Copyright (c) 1994, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.io;
27
28 import java.nio.channels.FileChannel;
29 import java.util.concurrent.atomic.AtomicBoolean;
30 import jdk.internal.misc.JavaIORandomAccessFileAccess;
31 import jdk.internal.misc.SharedSecrets;
32 import sun.nio.ch.FileChannelImpl;
33
34
35 /**
36 * Instances of this class support both reading and writing to a
37 * random access file. A random access file behaves like a large
38 * array of bytes stored in the file system. There is a kind of cursor,
39 * or index into the implied array, called the <em>file pointer</em>;
40 * input operations read bytes starting at the file pointer and advance
41 * the file pointer past the bytes read. If the random access file is
42 * created in read/write mode, then output operations are also available;
43 * output operations write bytes starting at the file pointer and advance
44 * the file pointer past the bytes written. Output operations that write
45 * past the current end of the implied array cause the array to be
46 * extended. The file pointer can be read by the
47 * {@code getFilePointer} method and set by the {@code seek}
48 * method.
49 * <p>
50 * It is generally true of all the reading routines in this class that
51 * if end-of-file is reached before the desired number of bytes has been
52 * read, an {@code EOFException} (which is a kind of
53 * {@code IOException}) is thrown. If any byte cannot be read for
54 * any reason other than end-of-file, an {@code IOException} other
55 * than {@code EOFException} is thrown. In particular, an
56 * {@code IOException} may be thrown if the stream has been closed.
57 *
58 * @author unascribed
59 * @since 1.0
60 */
61
62 public class RandomAccessFile implements DataOutput, DataInput, Closeable {
63
64 private FileDescriptor fd;
65 private volatile FileChannel channel;
66 private boolean rw;
67
68 /**
69 * The path of the referenced file
70 * (null if the stream is created with a file descriptor)
71 */
72 private final String path;
73
74 private final AtomicBoolean closed = new AtomicBoolean(false);
75
76 private static final int O_RDONLY = 1;
77 private static final int O_RDWR = 2;
78 private static final int O_SYNC = 4;
79 private static final int O_DSYNC = 8;
80 private static final int O_TEMPORARY = 16;
81
82 /**
83 * Creates a random access file stream to read from, and optionally
84 * to write to, a file with the specified name. A new
85 * {@link FileDescriptor} object is created to represent the
86 * connection to the file.
87 *
88 * <p> The {@code mode} argument specifies the access mode with which the
89 * file is to be opened. The permitted values and their meanings are as
90 * specified for the <a
91 * href="#mode">{@code RandomAccessFile(File,String)}</a> constructor.
92 *
93 * <p>
94 * If there is a security manager, its {@code checkRead} method
95 * is called with the {@code name} argument
96 * as its argument to see if read access to the file is allowed.
97 * If the mode allows writing, the security manager's
98 * {@code checkWrite} method
99 * is also called with the {@code name} argument
100 * as its argument to see if write access to the file is allowed.
101 *
102 * @param name the system-dependent filename
103 * @param mode the access <a href="#mode">mode</a>
104 * @exception IllegalArgumentException if the mode argument is not equal
105 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
106 * {@code "rwd"}
107 * @exception FileNotFoundException
108 * if the mode is {@code "r"} but the given string does not
109 * denote an existing regular file, or if the mode begins with
110 * {@code "rw"} but the given string does not denote an
111 * existing, writable regular file and a new regular file of
112 * that name cannot be created, or if some other error occurs
113 * while opening or creating the file
114 * @exception SecurityException if a security manager exists and its
115 * {@code checkRead} method denies read access to the file
116 * or the mode is {@code "rw"} and the security manager's
117 * {@code checkWrite} method denies write access to the file
118 * @see java.lang.SecurityException
119 * @see java.lang.SecurityManager#checkRead(java.lang.String)
120 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
121 * @revised 1.4
122 * @spec JSR-51
123 */
124 public RandomAccessFile(String name, String mode)
125 throws FileNotFoundException
126 {
127 this(name != null ? new File(name) : null, mode);
128 }
129
130 /**
131 * Creates a random access file stream to read from, and optionally to
132 * write to, the file specified by the {@link File} argument. A new {@link
133 * FileDescriptor} object is created to represent this file connection.
134 *
135 * <p>The <a id="mode">{@code mode}</a> argument specifies the access mode
136 * in which the file is to be opened. The permitted values and their
137 * meanings are:
138 *
139 * <table class="striped">
140 * <caption style="display:none">Access mode permitted values and meanings</caption>
141 * <thead>
142 * <tr><th style="text-align:left">Value</th><th style="text-align:left">Meaning</th></tr>
143 * </thead>
144 * <tbody>
145 * <tr><td style="vertical-align:top">{@code "r"}</td>
146 * <td> Open for reading only. Invoking any of the {@code write}
147 * methods of the resulting object will cause an
148 * {@link java.io.IOException} to be thrown.</td></tr>
149 * <tr><td style="vertical-align:top">{@code "rw"}</td>
150 * <td> Open for reading and writing. If the file does not already
151 * exist then an attempt will be made to create it.</td></tr>
152 * <tr><td style="vertical-align:top">{@code "rws"}</td>
153 * <td> Open for reading and writing, as with {@code "rw"}, and also
154 * require that every update to the file's content or metadata be
155 * written synchronously to the underlying storage device.</td></tr>
156 * <tr><td style="vertical-align:top">{@code "rwd"}</td>
157 * <td> Open for reading and writing, as with {@code "rw"}, and also
158 * require that every update to the file's content be written
159 * synchronously to the underlying storage device.</td></tr>
160 * </tbody>
161 * </table>
162 *
163 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link
164 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of
165 * the {@link java.nio.channels.FileChannel} class, passing arguments of
166 * {@code true} and {@code false}, respectively, except that they always
167 * apply to every I/O operation and are therefore often more efficient. If
168 * the file resides on a local storage device then when an invocation of a
169 * method of this class returns it is guaranteed that all changes made to
170 * the file by that invocation will have been written to that device. This
171 * is useful for ensuring that critical information is not lost in the
172 * event of a system crash. If the file does not reside on a local device
173 * then no such guarantee is made.
174 *
175 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O
176 * operations performed. Using {@code "rwd"} only requires updates to the
177 * file's content to be written to storage; using {@code "rws"} requires
178 * updates to both the file's content and its metadata to be written, which
179 * generally requires at least one more low-level I/O operation.
180 *
181 * <p>If there is a security manager, its {@code checkRead} method is
182 * called with the pathname of the {@code file} argument as its
183 * argument to see if read access to the file is allowed. If the mode
184 * allows writing, the security manager's {@code checkWrite} method is
185 * also called with the path argument to see if write access to the file is
186 * allowed.
187 *
188 * @param file the file object
189 * @param mode the access mode, as described
190 * <a href="#mode">above</a>
191 * @exception IllegalArgumentException if the mode argument is not equal
192 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
193 * {@code "rwd"}
194 * @exception FileNotFoundException
195 * if the mode is {@code "r"} but the given file object does
196 * not denote an existing regular file, or if the mode begins
197 * with {@code "rw"} but the given file object does not denote
198 * an existing, writable regular file and a new regular file of
199 * that name cannot be created, or if some other error occurs
200 * while opening or creating the file
201 * @exception SecurityException if a security manager exists and its
202 * {@code checkRead} method denies read access to the file
203 * or the mode is {@code "rw"} and the security manager's
204 * {@code checkWrite} method denies write access to the file
205 * @see java.lang.SecurityManager#checkRead(java.lang.String)
206 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
207 * @see java.nio.channels.FileChannel#force(boolean)
208 * @revised 1.4
209 * @spec JSR-51
210 */
211 public RandomAccessFile(File file, String mode)
212 throws FileNotFoundException
213 {
214 this(file, mode, false);
215 }
216
217 private RandomAccessFile(File file, String mode, boolean openAndDelete)
218 throws FileNotFoundException
219 {
220 String name = (file != null ? file.getPath() : null);
221 int imode = -1;
222 if (mode.equals("r"))
223 imode = O_RDONLY;
224 else if (mode.startsWith("rw")) {
225 imode = O_RDWR;
226 rw = true;
227 if (mode.length() > 2) {
228 if (mode.equals("rws"))
229 imode |= O_SYNC;
230 else if (mode.equals("rwd"))
231 imode |= O_DSYNC;
232 else
233 imode = -1;
234 }
235 }
236 if (openAndDelete)
237 imode |= O_TEMPORARY;
238 if (imode < 0)
239 throw new IllegalArgumentException("Illegal mode \"" + mode
240 + "\" must be one of "
241 + "\"r\", \"rw\", \"rws\","
242 + " or \"rwd\"");
243 SecurityManager security = System.getSecurityManager();
244 if (security != null) {
245 security.checkRead(name);
246 if (rw) {
247 security.checkWrite(name);
248 }
249 }
250 if (name == null) {
251 throw new NullPointerException();
252 }
253 if (file.isInvalid()) {
254 throw new FileNotFoundException("Invalid file path");
255 }
256 fd = new FileDescriptor();
257 fd.attach(this);
258 path = name;
259 open(name, imode);
260 }
261
262 /**
263 * Returns the opaque file descriptor object associated with this
264 * stream.
265 *
266 * @return the file descriptor object associated with this stream.
267 * @exception IOException if an I/O error occurs.
268 * @see java.io.FileDescriptor
269 */
270 public final FileDescriptor getFD() throws IOException {
271 if (fd != null) {
272 return fd;
273 }
274 throw new IOException();
275 }
276
277 /**
278 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
279 * object associated with this file.
280 *
281 * <p> The {@link java.nio.channels.FileChannel#position()
282 * position} of the returned channel will always be equal to
283 * this object's file-pointer offset as returned by the {@link
284 * #getFilePointer getFilePointer} method. Changing this object's
285 * file-pointer offset, whether explicitly or by reading or writing bytes,
286 * will change the position of the channel, and vice versa. Changing the
287 * file's length via this object will change the length seen via the file
288 * channel, and vice versa.
289 *
290 * @return the file channel associated with this file
291 *
292 * @since 1.4
293 * @spec JSR-51
294 */
295 public final FileChannel getChannel() {
296 FileChannel fc = this.channel;
297 if (fc == null) {
298 synchronized (this) {
299 fc = this.channel;
300 if (fc == null) {
301 this.channel = fc = FileChannelImpl.open(fd, path, true, rw, this);
302 if (closed.get()) {
303 try {
304 fc.close();
305 } catch (IOException ioe) {
306 throw new InternalError(ioe); // should not happen
307 }
308 }
309 }
310 }
311 }
312 return fc;
313 }
314
315 /**
316 * Opens a file and returns the file descriptor. The file is
317 * opened in read-write mode if the O_RDWR bit in {@code mode}
318 * is true, else the file is opened as read-only.
319 * If the {@code name} refers to a directory, an IOException
320 * is thrown.
321 *
322 * @param name the name of the file
323 * @param mode the mode flags, a combination of the O_ constants
324 * defined above
325 */
326 private native void open0(String name, int mode)
327 throws FileNotFoundException;
328
329 // wrap native call to allow instrumentation
330 /**
331 * Opens a file and returns the file descriptor. The file is
332 * opened in read-write mode if the O_RDWR bit in {@code mode}
333 * is true, else the file is opened as read-only.
334 * If the {@code name} refers to a directory, an IOException
335 * is thrown.
336 *
337 * @param name the name of the file
338 * @param mode the mode flags, a combination of the O_ constants
339 * defined above
340 */
341 private void open(String name, int mode)
342 throws FileNotFoundException {
343 open0(name, mode);
344 }
345
346 // 'Read' primitives
347
348 /**
349 * Reads a byte of data from this file. The byte is returned as an
350 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This
351 * method blocks if no input is yet available.
352 * <p>
353 * Although {@code RandomAccessFile} is not a subclass of
354 * {@code InputStream}, this method behaves in exactly the same
355 * way as the {@link InputStream#read()} method of
356 * {@code InputStream}.
357 *
358 * @return the next byte of data, or {@code -1} if the end of the
359 * file has been reached.
360 * @exception IOException if an I/O error occurs. Not thrown if
361 * end-of-file has been reached.
362 */
363 public int read() throws IOException {
364 return read0();
365 }
366
367 private native int read0() throws IOException;
368
369 /**
370 * Reads a sub array as a sequence of bytes.
371 * @param b the buffer into which the data is read.
372 * @param off the start offset of the data.
373 * @param len the number of bytes to read.
374 * @exception IOException If an I/O error has occurred.
375 */
376 private native int readBytes(byte b[], int off, int len) throws IOException;
377
378 /**
379 * Reads up to {@code len} bytes of data from this file into an
380 * array of bytes. This method blocks until at least one byte of input
381 * is available.
382 * <p>
383 * Although {@code RandomAccessFile} is not a subclass of
384 * {@code InputStream}, this method behaves in exactly the
385 * same way as the {@link InputStream#read(byte[], int, int)} method of
386 * {@code InputStream}.
387 *
388 * @param b the buffer into which the data is read.
389 * @param off the start offset in array {@code b}
390 * at which the data is written.
391 * @param len the maximum number of bytes read.
392 * @return the total number of bytes read into the buffer, or
393 * {@code -1} if there is no more data because the end of
394 * the file has been reached.
395 * @exception IOException If the first byte cannot be read for any reason
396 * other than end of file, or if the random access file has been closed, or if
397 * some other I/O error occurs.
398 * @exception NullPointerException If {@code b} is {@code null}.
399 * @exception IndexOutOfBoundsException If {@code off} is negative,
400 * {@code len} is negative, or {@code len} is greater than
401 * {@code b.length - off}
402 */
403 public int read(byte b[], int off, int len) throws IOException {
404 return readBytes(b, off, len);
405 }
406
407 /**
408 * Reads up to {@code b.length} bytes of data from this file
409 * into an array of bytes. This method blocks until at least one byte
410 * of input is available.
411 * <p>
412 * Although {@code RandomAccessFile} is not a subclass of
413 * {@code InputStream}, this method behaves in exactly the
414 * same way as the {@link InputStream#read(byte[])} method of
415 * {@code InputStream}.
416 *
417 * @param b the buffer into which the data is read.
418 * @return the total number of bytes read into the buffer, or
419 * {@code -1} if there is no more data because the end of
420 * this file has been reached.
421 * @exception IOException If the first byte cannot be read for any reason
422 * other than end of file, or if the random access file has been closed, or if
423 * some other I/O error occurs.
424 * @exception NullPointerException If {@code b} is {@code null}.
425 */
426 public int read(byte b[]) throws IOException {
427 return readBytes(b, 0, b.length);
428 }
429
430 /**
431 * Reads {@code b.length} bytes from this file into the byte
432 * array, starting at the current file pointer. This method reads
433 * repeatedly from the file until the requested number of bytes are
434 * read. This method blocks until the requested number of bytes are
435 * read, the end of the stream is detected, or an exception is thrown.
436 *
437 * @param b the buffer into which the data is read.
438 * @throws NullPointerException if {@code b} is {@code null}.
439 * @throws EOFException if this file reaches the end before reading
440 * all the bytes.
441 * @throws IOException if an I/O error occurs.
442 */
443 public final void readFully(byte b[]) throws IOException {
444 readFully(b, 0, b.length);
445 }
446
447 /**
448 * Reads exactly {@code len} bytes from this file into the byte
449 * array, starting at the current file pointer. This method reads
450 * repeatedly from the file until the requested number of bytes are
451 * read. This method blocks until the requested number of bytes are
452 * read, the end of the stream is detected, or an exception is thrown.
453 *
454 * @param b the buffer into which the data is read.
455 * @param off the start offset into the data array {@code b}.
456 * @param len the number of bytes to read.
457 * @throws NullPointerException if {@code b} is {@code null}.
458 * @throws IndexOutOfBoundsException if {@code off} is negative,
459 * {@code len} is negative, or {@code len} is greater than
460 * {@code b.length - off}.
461 * @throws EOFException if this file reaches the end before reading
462 * all the bytes.
463 * @throws IOException if an I/O error occurs.
464 */
465 public final void readFully(byte b[], int off, int len) throws IOException {
466 int n = 0;
467 do {
468 int count = this.read(b, off + n, len - n);
469 if (count < 0)
470 throw new EOFException();
471 n += count;
472 } while (n < len);
473 }
474
475 /**
476 * Attempts to skip over {@code n} bytes of input discarding the
477 * skipped bytes.
478 * <p>
479 *
480 * This method may skip over some smaller number of bytes, possibly zero.
481 * This may result from any of a number of conditions; reaching end of
482 * file before {@code n} bytes have been skipped is only one
483 * possibility. This method never throws an {@code EOFException}.
484 * The actual number of bytes skipped is returned. If {@code n}
485 * is negative, no bytes are skipped.
486 *
487 * @param n the number of bytes to be skipped.
488 * @return the actual number of bytes skipped.
489 * @exception IOException if an I/O error occurs.
490 */
491 public int skipBytes(int n) throws IOException {
492 long pos;
493 long len;
494 long newpos;
495
496 if (n <= 0) {
497 return 0;
498 }
499 pos = getFilePointer();
500 len = length();
501 newpos = pos + n;
502 if (newpos > len) {
503 newpos = len;
504 }
505 seek(newpos);
506
507 /* return the actual number of bytes skipped */
508 return (int) (newpos - pos);
509 }
510
511 // 'Write' primitives
512
513 /**
514 * Writes the specified byte to this file. The write starts at
515 * the current file pointer.
516 *
517 * @param b the {@code byte} to be written.
518 * @exception IOException if an I/O error occurs.
519 */
520 public void write(int b) throws IOException {
521 write0(b);
522 }
523
524 private native void write0(int b) throws IOException;
525
526 /**
527 * Writes a sub array as a sequence of bytes.
528 * @param b the data to be written
529
530 * @param off the start offset in the data
531 * @param len the number of bytes that are written
532 * @exception IOException If an I/O error has occurred.
533 */
534 private native void writeBytes(byte b[], int off, int len) throws IOException;
535
536 /**
537 * Writes {@code b.length} bytes from the specified byte array
538 * to this file, starting at the current file pointer.
539 *
540 * @param b the data.
541 * @exception IOException if an I/O error occurs.
542 */
543 public void write(byte b[]) throws IOException {
544 writeBytes(b, 0, b.length);
545 }
546
547 /**
548 * Writes {@code len} bytes from the specified byte array
549 * starting at offset {@code off} to this file.
550 *
551 * @param b the data.
552 * @param off the start offset in the data.
553 * @param len the number of bytes to write.
554 * @exception IOException if an I/O error occurs.
555 */
556 public void write(byte b[], int off, int len) throws IOException {
557 writeBytes(b, off, len);
558 }
559
560 // 'Random access' stuff
561
562 /**
563 * Returns the current offset in this file.
564 *
565 * @return the offset from the beginning of the file, in bytes,
566 * at which the next read or write occurs.
567 * @exception IOException if an I/O error occurs.
568 */
569 public native long getFilePointer() throws IOException;
570
571 /**
572 * Sets the file-pointer offset, measured from the beginning of this
573 * file, at which the next read or write occurs. The offset may be
574 * set beyond the end of the file. Setting the offset beyond the end
575 * of the file does not change the file length. The file length will
576 * change only by writing after the offset has been set beyond the end
577 * of the file.
578 *
579 * @param pos the offset position, measured in bytes from the
580 * beginning of the file, at which to set the file
581 * pointer.
582 * @exception IOException if {@code pos} is less than
583 * {@code 0} or if an I/O error occurs.
584 */
585 public void seek(long pos) throws IOException {
586 if (pos < 0) {
587 throw new IOException("Negative seek offset");
588 } else {
589 seek0(pos);
590 }
591 }
592
593 private native void seek0(long pos) throws IOException;
594
595 /**
596 * Returns the length of this file.
597 *
598 * @return the length of this file, measured in bytes.
599 * @exception IOException if an I/O error occurs.
600 */
601 public native long length() throws IOException;
602
603 /**
604 * Sets the length of this file.
605 *
606 * <p> If the present length of the file as returned by the
607 * {@code length} method is greater than the {@code newLength}
608 * argument then the file will be truncated. In this case, if the file
609 * offset as returned by the {@code getFilePointer} method is greater
610 * than {@code newLength} then after this method returns the offset
611 * will be equal to {@code newLength}.
612 *
613 * <p> If the present length of the file as returned by the
614 * {@code length} method is smaller than the {@code newLength}
615 * argument then the file will be extended. In this case, the contents of
616 * the extended portion of the file are not defined.
617 *
618 * @param newLength The desired length of the file
619 * @exception IOException If an I/O error occurs
620 * @since 1.2
621 */
622 public native void setLength(long newLength) throws IOException;
623
624 /**
625 * Closes this random access file stream and releases any system
626 * resources associated with the stream. A closed random access
627 * file cannot perform input or output operations and cannot be
628 * reopened.
629 *
630 * <p> If this file has an associated channel then the channel is closed
631 * as well.
632 *
633 * @exception IOException if an I/O error occurs.
634 *
635 * @revised 1.4
636 * @spec JSR-51
637 */
638 public void close() throws IOException {
639 if (!closed.compareAndSet(false, true)) {
640 // if compareAndSet() returns false closed was already true
641 return;
642 }
643
644 FileChannel fc = channel;
645 if (fc != null) {
646 fc.close();
647 }
648
649 fd.closeAll(new Closeable() {
650 public void close() throws IOException {
651 close0();
652 }
653 });
654 }
655
656 //
657 // Some "reading/writing Java data types" methods stolen from
658 // DataInputStream and DataOutputStream.
659 //
660
661 /**
662 * Reads a {@code boolean} from this file. This method reads a
663 * single byte from the file, starting at the current file pointer.
664 * A value of {@code 0} represents
665 * {@code false}. Any other value represents {@code true}.
666 * This method blocks until the byte is read, the end of the stream
667 * is detected, or an exception is thrown.
668 *
669 * @return the {@code boolean} value read.
670 * @exception EOFException if this file has reached the end.
671 * @exception IOException if an I/O error occurs.
672 */
673 public final boolean readBoolean() throws IOException {
674 int ch = this.read();
675 if (ch < 0)
676 throw new EOFException();
677 return (ch != 0);
678 }
679
680 /**
681 * Reads a signed eight-bit value from this file. This method reads a
682 * byte from the file, starting from the current file pointer.
683 * If the byte read is {@code b}, where
684 * <code>0 <= b <= 255</code>,
685 * then the result is:
686 * <blockquote><pre>
687 * (byte)(b)
688 * </pre></blockquote>
689 * <p>
690 * This method blocks until the byte is read, the end of the stream
691 * is detected, or an exception is thrown.
692 *
693 * @return the next byte of this file as a signed eight-bit
694 * {@code byte}.
695 * @exception EOFException if this file has reached the end.
696 * @exception IOException if an I/O error occurs.
697 */
698 public final byte readByte() throws IOException {
699 int ch = this.read();
700 if (ch < 0)
701 throw new EOFException();
702 return (byte)(ch);
703 }
704
705 /**
706 * Reads an unsigned eight-bit number from this file. This method reads
707 * a byte from this file, starting at the current file pointer,
708 * and returns that byte.
709 * <p>
710 * This method blocks until the byte is read, the end of the stream
711 * is detected, or an exception is thrown.
712 *
713 * @return the next byte of this file, interpreted as an unsigned
714 * eight-bit number.
715 * @exception EOFException if this file has reached the end.
716 * @exception IOException if an I/O error occurs.
717 */
718 public final int readUnsignedByte() throws IOException {
719 int ch = this.read();
720 if (ch < 0)
721 throw new EOFException();
722 return ch;
723 }
724
725 /**
726 * Reads a signed 16-bit number from this file. The method reads two
727 * bytes from this file, starting at the current file pointer.
728 * If the two bytes read, in order, are
729 * {@code b1} and {@code b2}, where each of the two values is
730 * between {@code 0} and {@code 255}, inclusive, then the
731 * result is equal to:
732 * <blockquote><pre>
733 * (short)((b1 << 8) | b2)
734 * </pre></blockquote>
735 * <p>
736 * This method blocks until the two bytes are read, the end of the
737 * stream is detected, or an exception is thrown.
738 *
739 * @return the next two bytes of this file, interpreted as a signed
740 * 16-bit number.
741 * @exception EOFException if this file reaches the end before reading
742 * two bytes.
743 * @exception IOException if an I/O error occurs.
744 */
745 public final short readShort() throws IOException {
746 int ch1 = this.read();
747 int ch2 = this.read();
748 if ((ch1 | ch2) < 0)
749 throw new EOFException();
750 return (short)((ch1 << 8) + (ch2 << 0));
751 }
752
753 /**
754 * Reads an unsigned 16-bit number from this file. This method reads
755 * two bytes from the file, starting at the current file pointer.
756 * If the bytes read, in order, are
757 * {@code b1} and {@code b2}, where
758 * <code>0 <= b1, b2 <= 255</code>,
759 * then the result is equal to:
760 * <blockquote><pre>
761 * (b1 << 8) | b2
762 * </pre></blockquote>
763 * <p>
764 * This method blocks until the two bytes are read, the end of the
765 * stream is detected, or an exception is thrown.
766 *
767 * @return the next two bytes of this file, interpreted as an unsigned
768 * 16-bit integer.
769 * @exception EOFException if this file reaches the end before reading
770 * two bytes.
771 * @exception IOException if an I/O error occurs.
772 */
773 public final int readUnsignedShort() throws IOException {
774 int ch1 = this.read();
775 int ch2 = this.read();
776 if ((ch1 | ch2) < 0)
777 throw new EOFException();
778 return (ch1 << 8) + (ch2 << 0);
779 }
780
781 /**
782 * Reads a character from this file. This method reads two
783 * bytes from the file, starting at the current file pointer.
784 * If the bytes read, in order, are
785 * {@code b1} and {@code b2}, where
786 * <code>0 <= b1, b2 <= 255</code>,
787 * then the result is equal to:
788 * <blockquote><pre>
789 * (char)((b1 << 8) | b2)
790 * </pre></blockquote>
791 * <p>
792 * This method blocks until the two bytes are read, the end of the
793 * stream is detected, or an exception is thrown.
794 *
795 * @return the next two bytes of this file, interpreted as a
796 * {@code char}.
797 * @exception EOFException if this file reaches the end before reading
798 * two bytes.
799 * @exception IOException if an I/O error occurs.
800 */
801 public final char readChar() throws IOException {
802 int ch1 = this.read();
803 int ch2 = this.read();
804 if ((ch1 | ch2) < 0)
805 throw new EOFException();
806 return (char)((ch1 << 8) + (ch2 << 0));
807 }
808
809 /**
810 * Reads a signed 32-bit integer from this file. This method reads 4
811 * bytes from the file, starting at the current file pointer.
812 * If the bytes read, in order, are {@code b1},
813 * {@code b2}, {@code b3}, and {@code b4}, where
814 * <code>0 <= b1, b2, b3, b4 <= 255</code>,
815 * then the result is equal to:
816 * <blockquote><pre>
817 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
818 * </pre></blockquote>
819 * <p>
820 * This method blocks until the four bytes are read, the end of the
821 * stream is detected, or an exception is thrown.
822 *
823 * @return the next four bytes of this file, interpreted as an
824 * {@code int}.
825 * @exception EOFException if this file reaches the end before reading
826 * four bytes.
827 * @exception IOException if an I/O error occurs.
828 */
829 public final int readInt() throws IOException {
830 int ch1 = this.read();
831 int ch2 = this.read();
832 int ch3 = this.read();
833 int ch4 = this.read();
834 if ((ch1 | ch2 | ch3 | ch4) < 0)
835 throw new EOFException();
836 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
837 }
838
839 /**
840 * Reads a signed 64-bit integer from this file. This method reads eight
841 * bytes from the file, starting at the current file pointer.
842 * If the bytes read, in order, are
843 * {@code b1}, {@code b2}, {@code b3},
844 * {@code b4}, {@code b5}, {@code b6},
845 * {@code b7}, and {@code b8,} where:
846 * <blockquote><pre>
847 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
848 * </pre></blockquote>
849 * <p>
850 * then the result is equal to:
851 * <blockquote><pre>
852 * ((long)b1 << 56) + ((long)b2 << 48)
853 * + ((long)b3 << 40) + ((long)b4 << 32)
854 * + ((long)b5 << 24) + ((long)b6 << 16)
855 * + ((long)b7 << 8) + b8
856 * </pre></blockquote>
857 * <p>
858 * This method blocks until the eight bytes are read, the end of the
859 * stream is detected, or an exception is thrown.
860 *
861 * @return the next eight bytes of this file, interpreted as a
862 * {@code long}.
863 * @exception EOFException if this file reaches the end before reading
864 * eight bytes.
865 * @exception IOException if an I/O error occurs.
866 */
867 public final long readLong() throws IOException {
868 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
869 }
870
871 /**
872 * Reads a {@code float} from this file. This method reads an
873 * {@code int} value, starting at the current file pointer,
874 * as if by the {@code readInt} method
875 * and then converts that {@code int} to a {@code float}
876 * using the {@code intBitsToFloat} method in class
877 * {@code Float}.
878 * <p>
879 * This method blocks until the four bytes are read, the end of the
880 * stream is detected, or an exception is thrown.
881 *
882 * @return the next four bytes of this file, interpreted as a
883 * {@code float}.
884 * @exception EOFException if this file reaches the end before reading
885 * four bytes.
886 * @exception IOException if an I/O error occurs.
887 * @see java.io.RandomAccessFile#readInt()
888 * @see java.lang.Float#intBitsToFloat(int)
889 */
890 public final float readFloat() throws IOException {
891 return Float.intBitsToFloat(readInt());
892 }
893
894 /**
895 * Reads a {@code double} from this file. This method reads a
896 * {@code long} value, starting at the current file pointer,
897 * as if by the {@code readLong} method
898 * and then converts that {@code long} to a {@code double}
899 * using the {@code longBitsToDouble} method in
900 * class {@code Double}.
901 * <p>
902 * This method blocks until the eight bytes are read, the end of the
903 * stream is detected, or an exception is thrown.
904 *
905 * @return the next eight bytes of this file, interpreted as a
906 * {@code double}.
907 * @exception EOFException if this file reaches the end before reading
908 * eight bytes.
909 * @exception IOException if an I/O error occurs.
910 * @see java.io.RandomAccessFile#readLong()
911 * @see java.lang.Double#longBitsToDouble(long)
912 */
913 public final double readDouble() throws IOException {
914 return Double.longBitsToDouble(readLong());
915 }
916
917 /**
918 * Reads the next line of text from this file. This method successively
919 * reads bytes from the file, starting at the current file pointer,
920 * until it reaches a line terminator or the end
921 * of the file. Each byte is converted into a character by taking the
922 * byte's value for the lower eight bits of the character and setting the
923 * high eight bits of the character to zero. This method does not,
924 * therefore, support the full Unicode character set.
925 *
926 * <p> A line of text is terminated by a carriage-return character
927 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a
928 * carriage-return character immediately followed by a newline character,
929 * or the end of the file. Line-terminating characters are discarded and
930 * are not included as part of the string returned.
931 *
932 * <p> This method blocks until a newline character is read, a carriage
933 * return and the byte following it are read (to see if it is a newline),
934 * the end of the file is reached, or an exception is thrown.
935 *
936 * @return the next line of text from this file, or null if end
937 * of file is encountered before even one byte is read.
938 * @exception IOException if an I/O error occurs.
939 */
940
941 public final String readLine() throws IOException {
942 StringBuilder input = new StringBuilder();
943 int c = -1;
944 boolean eol = false;
945
946 while (!eol) {
947 switch (c = read()) {
948 case -1:
949 case '\n':
950 eol = true;
951 break;
952 case '\r':
953 eol = true;
954 long cur = getFilePointer();
955 if ((read()) != '\n') {
956 seek(cur);
957 }
958 break;
959 default:
960 input.append((char)c);
961 break;
962 }
963 }
964
965 if ((c == -1) && (input.length() == 0)) {
966 return null;
967 }
968 return input.toString();
969 }
970
971 /**
972 * Reads in a string from this file. The string has been encoded
973 * using a
974 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
975 * format.
976 * <p>
977 * The first two bytes are read, starting from the current file
978 * pointer, as if by
979 * {@code readUnsignedShort}. This value gives the number of
980 * following bytes that are in the encoded string, not
981 * the length of the resulting string. The following bytes are then
982 * interpreted as bytes encoding characters in the modified UTF-8 format
983 * and are converted into characters.
984 * <p>
985 * This method blocks until all the bytes are read, the end of the
986 * stream is detected, or an exception is thrown.
987 *
988 * @return a Unicode string.
989 * @exception EOFException if this file reaches the end before
990 * reading all the bytes.
991 * @exception IOException if an I/O error occurs.
992 * @exception UTFDataFormatException if the bytes do not represent
993 * valid modified UTF-8 encoding of a Unicode string.
994 * @see java.io.RandomAccessFile#readUnsignedShort()
995 */
996 public final String readUTF() throws IOException {
997 return DataInputStream.readUTF(this);
998 }
999
1000 /**
1001 * Writes a {@code boolean} to the file as a one-byte value. The
1002 * value {@code true} is written out as the value
1003 * {@code (byte)1}; the value {@code false} is written out
1004 * as the value {@code (byte)0}. The write starts at
1005 * the current position of the file pointer.
1006 *
1007 * @param v a {@code boolean} value to be written.
1008 * @exception IOException if an I/O error occurs.
1009 */
1010 public final void writeBoolean(boolean v) throws IOException {
1011 write(v ? 1 : 0);
1012 //written++;
1013 }
1014
1015 /**
1016 * Writes a {@code byte} to the file as a one-byte value. The
1017 * write starts at the current position of the file pointer.
1018 *
1019 * @param v a {@code byte} value to be written.
1020 * @exception IOException if an I/O error occurs.
1021 */
1022 public final void writeByte(int v) throws IOException {
1023 write(v);
1024 //written++;
1025 }
1026
1027 /**
1028 * Writes a {@code short} to the file as two bytes, high byte first.
1029 * The write starts at the current position of the file pointer.
1030 *
1031 * @param v a {@code short} to be written.
1032 * @exception IOException if an I/O error occurs.
1033 */
1034 public final void writeShort(int v) throws IOException {
1035 write((v >>> 8) & 0xFF);
1036 write((v >>> 0) & 0xFF);
1037 //written += 2;
1038 }
1039
1040 /**
1041 * Writes a {@code char} to the file as a two-byte value, high
1042 * byte first. The write starts at the current position of the
1043 * file pointer.
1044 *
1045 * @param v a {@code char} value to be written.
1046 * @exception IOException if an I/O error occurs.
1047 */
1048 public final void writeChar(int v) throws IOException {
1049 write((v >>> 8) & 0xFF);
1050 write((v >>> 0) & 0xFF);
1051 //written += 2;
1052 }
1053
1054 /**
1055 * Writes an {@code int} to the file as four bytes, high byte first.
1056 * The write starts at the current position of the file pointer.
1057 *
1058 * @param v an {@code int} to be written.
1059 * @exception IOException if an I/O error occurs.
1060 */
1061 public final void writeInt(int v) throws IOException {
1062 write((v >>> 24) & 0xFF);
1063 write((v >>> 16) & 0xFF);
1064 write((v >>> 8) & 0xFF);
1065 write((v >>> 0) & 0xFF);
1066 //written += 4;
1067 }
1068
1069 /**
1070 * Writes a {@code long} to the file as eight bytes, high byte first.
1071 * The write starts at the current position of the file pointer.
1072 *
1073 * @param v a {@code long} to be written.
1074 * @exception IOException if an I/O error occurs.
1075 */
1076 public final void writeLong(long v) throws IOException {
1077 write((int)(v >>> 56) & 0xFF);
1078 write((int)(v >>> 48) & 0xFF);
1079 write((int)(v >>> 40) & 0xFF);
1080 write((int)(v >>> 32) & 0xFF);
1081 write((int)(v >>> 24) & 0xFF);
1082 write((int)(v >>> 16) & 0xFF);
1083 write((int)(v >>> 8) & 0xFF);
1084 write((int)(v >>> 0) & 0xFF);
1085 //written += 8;
1086 }
1087
1088 /**
1089 * Converts the float argument to an {@code int} using the
1090 * {@code floatToIntBits} method in class {@code Float},
1091 * and then writes that {@code int} value to the file as a
1092 * four-byte quantity, high byte first. The write starts at the
1093 * current position of the file pointer.
1094 *
1095 * @param v a {@code float} value to be written.
1096 * @exception IOException if an I/O error occurs.
1097 * @see java.lang.Float#floatToIntBits(float)
1098 */
1099 public final void writeFloat(float v) throws IOException {
1100 writeInt(Float.floatToIntBits(v));
1101 }
1102
1103 /**
1104 * Converts the double argument to a {@code long} using the
1105 * {@code doubleToLongBits} method in class {@code Double},
1106 * and then writes that {@code long} value to the file as an
1107 * eight-byte quantity, high byte first. The write starts at the current
1108 * position of the file pointer.
1109 *
1110 * @param v a {@code double} value to be written.
1111 * @exception IOException if an I/O error occurs.
1112 * @see java.lang.Double#doubleToLongBits(double)
1113 */
1114 public final void writeDouble(double v) throws IOException {
1115 writeLong(Double.doubleToLongBits(v));
1116 }
1117
1118 /**
1119 * Writes the string to the file as a sequence of bytes. Each
1120 * character in the string is written out, in sequence, by discarding
1121 * its high eight bits. The write starts at the current position of
1122 * the file pointer.
1123 *
1124 * @param s a string of bytes to be written.
1125 * @exception IOException if an I/O error occurs.
1126 */
1127 @SuppressWarnings("deprecation")
1128 public final void writeBytes(String s) throws IOException {
1129 int len = s.length();
1130 byte[] b = new byte[len];
1131 s.getBytes(0, len, b, 0);
1132 writeBytes(b, 0, len);
1133 }
1134
1135 /**
1136 * Writes a string to the file as a sequence of characters. Each
1137 * character is written to the data output stream as if by the
1138 * {@code writeChar} method. The write starts at the current
1139 * position of the file pointer.
1140 *
1141 * @param s a {@code String} value to be written.
1142 * @exception IOException if an I/O error occurs.
1143 * @see java.io.RandomAccessFile#writeChar(int)
1144 */
1145 public final void writeChars(String s) throws IOException {
1146 int clen = s.length();
1147 int blen = 2*clen;
1148 byte[] b = new byte[blen];
1149 char[] c = new char[clen];
1150 s.getChars(0, clen, c, 0);
1151 for (int i = 0, j = 0; i < clen; i++) {
1152 b[j++] = (byte)(c[i] >>> 8);
1153 b[j++] = (byte)(c[i] >>> 0);
1154 }
1155 writeBytes(b, 0, blen);
1156 }
1157
1158 /**
1159 * Writes a string to the file using
1160 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1161 * encoding in a machine-independent manner.
1162 * <p>
1163 * First, two bytes are written to the file, starting at the
1164 * current file pointer, as if by the
1165 * {@code writeShort} method giving the number of bytes to
1166 * follow. This value is the number of bytes actually written out,
1167 * not the length of the string. Following the length, each character
1168 * of the string is output, in sequence, using the modified UTF-8 encoding
1169 * for each character.
1170 *
1171 * @param str a string to be written.
1172 * @exception IOException if an I/O error occurs.
1173 */
1174 public final void writeUTF(String str) throws IOException {
1175 DataOutputStream.writeUTF(str, this);
1176 }
1177
1178 private static native void initIDs();
1179
1180 private native void close0() throws IOException;
1181
1182 static {
1183 initIDs();
1184 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess()
1185 {
1186 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag
1187 // is only implemented/supported on windows.
1188 public RandomAccessFile openAndDelete(File file, String mode)
1189 throws IOException
1190 {
1191 return new RandomAccessFile(file, mode, true);
1192 }
1193 });
1194 }
1195 }