1 /*
2 * Copyright (c) 1994, 2018, 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
31 import jdk.internal.access.JavaIORandomAccessFileAccess;
32 import jdk.internal.access.SharedSecrets;
33 import sun.nio.ch.FileChannelImpl;
34
35
36 /**
37 * Instances of this class support both reading and writing to a
38 * random access file. A random access file behaves like a large
39 * array of bytes stored in the file system. There is a kind of cursor,
40 * or index into the implied array, called the <em>file pointer</em>;
41 * input operations read bytes starting at the file pointer and advance
42 * the file pointer past the bytes read. If the random access file is
43 * created in read/write mode, then output operations are also available;
44 * output operations write bytes starting at the file pointer and advance
45 * the file pointer past the bytes written. Output operations that write
46 * past the current end of the implied array cause the array to be
47 * extended. The file pointer can be read by the
48 * {@code getFilePointer} method and set by the {@code seek}
49 * method.
50 * <p>
51 * It is generally true of all the reading routines in this class that
52 * if end-of-file is reached before the desired number of bytes has been
53 * read, an {@code EOFException} (which is a kind of
54 * {@code IOException}) is thrown. If any byte cannot be read for
55 * any reason other than end-of-file, an {@code IOException} other
56 * than {@code EOFException} is thrown. In particular, an
57 * {@code IOException} may be thrown if the stream has been closed.
58 *
59 * @author unascribed
60 * @since 1.0
61 */
62
63 public class RandomAccessFile implements DataOutput, DataInput, Closeable {
64
65 private FileDescriptor fd;
66 private volatile FileChannel channel;
67 private boolean rw;
68
69 /**
70 * The path of the referenced file
71 * (null if the stream is created with a file descriptor)
72 */
73 private final String path;
74
75 private final AtomicBoolean closed = new AtomicBoolean(false);
76
77 private static final int O_RDONLY = 1;
78 private static final int O_RDWR = 2;
79 private static final int O_SYNC = 4;
80 private static final int O_DSYNC = 8;
81 private static final int O_TEMPORARY = 16;
82
83 /**
84 * Creates a random access file stream to read from, and optionally
85 * to write to, a file with the specified name. A new
86 * {@link FileDescriptor} object is created to represent the
87 * connection to the file.
88 *
89 * <p> The {@code mode} argument specifies the access mode with which the
90 * file is to be opened. The permitted values and their meanings are as
91 * specified for the <a
92 * href="#mode">{@code RandomAccessFile(File,String)}</a> constructor.
93 *
94 * <p>
95 * If there is a security manager, its {@code checkRead} method
96 * is called with the {@code name} argument
97 * as its argument to see if read access to the file is allowed.
98 * If the mode allows writing, the security manager's
99 * {@code checkWrite} method
100 * is also called with the {@code name} argument
101 * as its argument to see if write access to the file is allowed.
102 *
103 * @param name the system-dependent filename
104 * @param mode the access <a href="#mode">mode</a>
105 * @exception IllegalArgumentException if the mode argument is not equal
106 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
107 * {@code "rwd"}
108 * @exception FileNotFoundException
109 * if the mode is {@code "r"} but the given string does not
110 * denote an existing regular file, or if the mode begins with
111 * {@code "rw"} but the given string does not denote an
112 * existing, writable regular file and a new regular file of
113 * that name cannot be created, or if some other error occurs
114 * while opening or creating the file
115 * @exception SecurityException if a security manager exists and its
116 * {@code checkRead} method denies read access to the file
117 * or the mode is {@code "rw"} and the security manager's
118 * {@code checkWrite} method denies write access to the file
119 * @see java.lang.SecurityException
120 * @see java.lang.SecurityManager#checkRead(java.lang.String)
121 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
122 * @revised 1.4
123 * @spec JSR-51
124 */
125 public RandomAccessFile(String name, String mode)
126 throws FileNotFoundException
127 {
128 this(name != null ? new File(name) : null, mode);
129 }
130
131 /**
132 * Creates a random access file stream to read from, and optionally to
133 * write to, the file specified by the {@link File} argument. A new {@link
134 * FileDescriptor} object is created to represent this file connection.
135 *
136 * <p>The <a id="mode">{@code mode}</a> argument specifies the access mode
137 * in which the file is to be opened. The permitted values and their
138 * meanings are:
139 *
140 * <table class="striped">
141 * <caption style="display:none">Access mode permitted values and meanings</caption>
142 * <thead>
143 * <tr><th scope="col" style="text-align:left">Value</th><th scope="col" style="text-align:left">Meaning</th></tr>
144 * </thead>
145 * <tbody>
146 * <tr><th scope="row" style="vertical-align:top">{@code "r"}</th>
147 * <td> Open for reading only. Invoking any of the {@code write}
148 * methods of the resulting object will cause an
149 * {@link java.io.IOException} to be thrown.</td></tr>
150 * <tr><th scope="row" style="vertical-align:top">{@code "rw"}</th>
151 * <td> Open for reading and writing. If the file does not already
152 * exist then an attempt will be made to create it.</td></tr>
153 * <tr><th scope="row" style="vertical-align:top">{@code "rws"}</th>
154 * <td> Open for reading and writing, as with {@code "rw"}, and also
155 * require that every update to the file's content or metadata be
156 * written synchronously to the underlying storage device.</td></tr>
157 * <tr><th scope="row" style="vertical-align:top">{@code "rwd"}</th>
158 * <td> Open for reading and writing, as with {@code "rw"}, and also
159 * require that every update to the file's content be written
160 * synchronously to the underlying storage device.</td></tr>
161 * </tbody>
162 * </table>
163 *
164 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link
165 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of
166 * the {@link java.nio.channels.FileChannel} class, passing arguments of
167 * {@code true} and {@code false}, respectively, except that they always
168 * apply to every I/O operation and are therefore often more efficient. If
169 * the file resides on a local storage device then when an invocation of a
170 * method of this class returns it is guaranteed that all changes made to
171 * the file by that invocation will have been written to that device. This
172 * is useful for ensuring that critical information is not lost in the
173 * event of a system crash. If the file does not reside on a local device
174 * then no such guarantee is made.
175 *
176 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O
177 * operations performed. Using {@code "rwd"} only requires updates to the
178 * file's content to be written to storage; using {@code "rws"} requires
179 * updates to both the file's content and its metadata to be written, which
180 * generally requires at least one more low-level I/O operation.
181 *
182 * <p>If there is a security manager, its {@code checkRead} method is
183 * called with the pathname of the {@code file} argument as its
184 * argument to see if read access to the file is allowed. If the mode
185 * allows writing, the security manager's {@code checkWrite} method is
186 * also called with the path argument to see if write access to the file is
187 * allowed.
188 *
189 * @param file the file object
190 * @param mode the access mode, as described
191 * <a href="#mode">above</a>
192 * @exception IllegalArgumentException if the mode argument is not equal
193 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
194 * {@code "rwd"}
195 * @exception FileNotFoundException
196 * if the mode is {@code "r"} but the given file object does
197 * not denote an existing regular file, or if the mode begins
198 * with {@code "rw"} but the given file object does not denote
199 * an existing, writable regular file and a new regular file of
200 * that name cannot be created, or if some other error occurs
201 * while opening or creating the file
202 * @exception SecurityException if a security manager exists and its
203 * {@code checkRead} method denies read access to the file
204 * or the mode is {@code "rw"} and the security manager's
205 * {@code checkWrite} method denies write access to the file
206 * @see java.lang.SecurityManager#checkRead(java.lang.String)
207 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
208 * @see java.nio.channels.FileChannel#force(boolean)
209 * @revised 1.4
210 * @spec JSR-51
211 */
212 public RandomAccessFile(File file, String mode)
213 throws FileNotFoundException
214 {
215 this(file, mode, false);
216 }
217
218 private RandomAccessFile(File file, String mode, boolean openAndDelete)
219 throws FileNotFoundException
220 {
221 String name = (file != null ? file.getPath() : null);
222 int imode = -1;
223 if (mode.equals("r"))
224 imode = O_RDONLY;
225 else if (mode.startsWith("rw")) {
226 imode = O_RDWR;
227 rw = true;
228 if (mode.length() > 2) {
229 if (mode.equals("rws"))
230 imode |= O_SYNC;
231 else if (mode.equals("rwd"))
232 imode |= O_DSYNC;
233 else
234 imode = -1;
235 }
236 }
237 if (openAndDelete)
238 imode |= O_TEMPORARY;
239 if (imode < 0)
240 throw new IllegalArgumentException("Illegal mode \"" + mode
241 + "\" must be one of "
242 + "\"r\", \"rw\", \"rws\","
243 + " or \"rwd\"");
244 SecurityManager security = System.getSecurityManager();
245 if (security != null) {
246 security.checkRead(name);
247 if (rw) {
248 security.checkWrite(name);
249 }
250 }
251 if (name == null) {
252 throw new NullPointerException();
253 }
254 if (file.isInvalid()) {
255 throw new FileNotFoundException("Invalid file path");
256 }
257 fd = new FileDescriptor();
258 fd.attach(this);
259 path = name;
260 open(name, imode);
261 FileCleanable.register(fd); // open sets the fd, register the cleanup
262 }
263
264 /**
265 * Returns the opaque file descriptor object associated with this
266 * stream.
267 *
268 * @return the file descriptor object associated with this stream.
269 * @exception IOException if an I/O error occurs.
270 * @see java.io.FileDescriptor
271 */
272 public final FileDescriptor getFD() throws IOException {
273 if (fd != null) {
274 return fd;
275 }
276 throw new IOException();
277 }
278
279 /**
280 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
281 * object associated with this file.
282 *
283 * <p> The {@link java.nio.channels.FileChannel#position()
284 * position} of the returned channel will always be equal to
285 * this object's file-pointer offset as returned by the {@link
286 * #getFilePointer getFilePointer} method. Changing this object's
287 * file-pointer offset, whether explicitly or by reading or writing bytes,
288 * will change the position of the channel, and vice versa. Changing the
289 * file's length via this object will change the length seen via the file
290 * channel, and vice versa.
291 *
292 * @return the file channel associated with this file
293 *
294 * @since 1.4
295 * @spec JSR-51
296 */
297 public final FileChannel getChannel() {
298 FileChannel fc = this.channel;
299 if (fc == null) {
300 synchronized (this) {
301 fc = this.channel;
302 if (fc == null) {
303 this.channel = fc = FileChannelImpl.open(fd, path, true,
304 rw, false, this);
305 if (closed.get()) {
306 try {
307 fc.close();
308 } catch (IOException ioe) {
309 throw new InternalError(ioe); // should not happen
310 }
311 }
312 }
313 }
314 }
315 return fc;
316 }
317
318 /**
319 * Opens a file and returns the file descriptor. The file is
320 * opened in read-write mode if the O_RDWR bit in {@code mode}
321 * is true, else the file is opened as read-only.
322 * If the {@code name} refers to a directory, an IOException
323 * is thrown.
324 *
325 * @param name the name of the file
326 * @param mode the mode flags, a combination of the O_ constants
327 * defined above
328 */
329 private native void open0(String name, int mode)
330 throws FileNotFoundException;
331
332 // wrap native call to allow instrumentation
333 /**
334 * Opens a file and returns the file descriptor. The file is
335 * opened in read-write mode if the O_RDWR bit in {@code mode}
336 * is true, else the file is opened as read-only.
337 * If the {@code name} refers to a directory, an IOException
338 * is thrown.
339 *
340 * @param name the name of the file
341 * @param mode the mode flags, a combination of the O_ constants
342 * defined above
343 */
344 private void open(String name, int mode)
345 throws FileNotFoundException {
346 open0(name, mode);
347 }
348
349 // 'Read' primitives
350
351 /**
352 * Reads a byte of data from this file. The byte is returned as an
353 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This
354 * method blocks if no input is yet available.
355 * <p>
356 * Although {@code RandomAccessFile} is not a subclass of
357 * {@code InputStream}, this method behaves in exactly the same
358 * way as the {@link InputStream#read()} method of
359 * {@code InputStream}.
360 *
361 * @return the next byte of data, or {@code -1} if the end of the
362 * file has been reached.
363 * @exception IOException if an I/O error occurs. Not thrown if
364 * end-of-file has been reached.
365 */
366 public int read() throws IOException {
367 return read0();
368 }
369
370 private native int read0() throws IOException;
371
372 /**
373 * Reads a sub array as a sequence of bytes.
374 * @param b the buffer into which the data is read.
375 * @param off the start offset of the data.
376 * @param len the number of bytes to read.
377 * @exception IOException If an I/O error has occurred.
378 */
379 private native int readBytes(byte b[], int off, int len) throws IOException;
380
381 /**
382 * Reads up to {@code len} bytes of data from this file into an
383 * array of bytes. This method blocks until at least one byte of input
384 * is available.
385 * <p>
386 * Although {@code RandomAccessFile} is not a subclass of
387 * {@code InputStream}, this method behaves in exactly the
388 * same way as the {@link InputStream#read(byte[], int, int)} method of
389 * {@code InputStream}.
390 *
391 * @param b the buffer into which the data is read.
392 * @param off the start offset in array {@code b}
393 * at which the data is written.
394 * @param len the maximum number of bytes read.
395 * @return the total number of bytes read into the buffer, or
396 * {@code -1} if there is no more data because the end of
397 * the file has been reached.
398 * @exception IOException If the first byte cannot be read for any reason
399 * other than end of file, or if the random access file has been closed, or if
400 * some other I/O error occurs.
401 * @exception NullPointerException If {@code b} is {@code null}.
402 * @exception IndexOutOfBoundsException If {@code off} is negative,
403 * {@code len} is negative, or {@code len} is greater than
404 * {@code b.length - off}
405 */
406 public int read(byte b[], int off, int len) throws IOException {
407 return readBytes(b, off, len);
408 }
409
410 /**
411 * Reads up to {@code b.length} bytes of data from this file
412 * into an array of bytes. This method blocks until at least one byte
413 * of input is available.
414 * <p>
415 * Although {@code RandomAccessFile} is not a subclass of
416 * {@code InputStream}, this method behaves in exactly the
417 * same way as the {@link InputStream#read(byte[])} method of
418 * {@code InputStream}.
419 *
420 * @param b the buffer into which the data is read.
421 * @return the total number of bytes read into the buffer, or
422 * {@code -1} if there is no more data because the end of
423 * this file has been reached.
424 * @exception IOException If the first byte cannot be read for any reason
425 * other than end of file, or if the random access file has been closed, or if
426 * some other I/O error occurs.
427 * @exception NullPointerException If {@code b} is {@code null}.
428 */
429 public int read(byte b[]) throws IOException {
430 return readBytes(b, 0, b.length);
431 }
432
433 /**
434 * Reads {@code b.length} bytes from this file into the byte
435 * array, starting at the current file pointer. This method reads
436 * repeatedly from the file until the requested number of bytes are
437 * read. This method blocks until the requested number of bytes are
438 * read, the end of the stream is detected, or an exception is thrown.
439 *
440 * @param b the buffer into which the data is read.
441 * @throws NullPointerException if {@code b} is {@code null}.
442 * @throws EOFException if this file reaches the end before reading
443 * all the bytes.
444 * @throws IOException if an I/O error occurs.
445 */
446 public final void readFully(byte b[]) throws IOException {
447 readFully(b, 0, b.length);
448 }
449
450 /**
451 * Reads exactly {@code len} bytes from this file into the byte
452 * array, starting at the current file pointer. This method reads
453 * repeatedly from the file until the requested number of bytes are
454 * read. This method blocks until the requested number of bytes are
455 * read, the end of the stream is detected, or an exception is thrown.
456 *
457 * @param b the buffer into which the data is read.
458 * @param off the start offset into the data array {@code b}.
459 * @param len the number of bytes to read.
460 * @throws NullPointerException if {@code b} is {@code null}.
461 * @throws IndexOutOfBoundsException if {@code off} is negative,
462 * {@code len} is negative, or {@code len} is greater than
463 * {@code b.length - off}.
464 * @throws EOFException if this file reaches the end before reading
465 * all the bytes.
466 * @throws IOException if an I/O error occurs.
467 */
468 public final void readFully(byte b[], int off, int len) throws IOException {
469 int n = 0;
470 do {
471 int count = this.read(b, off + n, len - n);
472 if (count < 0)
473 throw new EOFException();
474 n += count;
475 } while (n < len);
476 }
477
478 /**
479 * Attempts to skip over {@code n} bytes of input discarding the
480 * skipped bytes.
481 * <p>
482 *
483 * This method may skip over some smaller number of bytes, possibly zero.
484 * This may result from any of a number of conditions; reaching end of
485 * file before {@code n} bytes have been skipped is only one
486 * possibility. This method never throws an {@code EOFException}.
487 * The actual number of bytes skipped is returned. If {@code n}
488 * is negative, no bytes are skipped.
489 *
490 * @param n the number of bytes to be skipped.
491 * @return the actual number of bytes skipped.
492 * @exception IOException if an I/O error occurs.
493 */
494 public int skipBytes(int n) throws IOException {
495 long pos;
496 long len;
497 long newpos;
498
499 if (n <= 0) {
500 return 0;
501 }
502 pos = getFilePointer();
503 len = length();
504 newpos = pos + n;
505 if (newpos > len) {
506 newpos = len;
507 }
508 seek(newpos);
509
510 /* return the actual number of bytes skipped */
511 return (int) (newpos - pos);
512 }
513
514 // 'Write' primitives
515
516 /**
517 * Writes the specified byte to this file. The write starts at
518 * the current file pointer.
519 *
520 * @param b the {@code byte} to be written.
521 * @exception IOException if an I/O error occurs.
522 */
523 public void write(int b) throws IOException {
524 write0(b);
525 }
526
527 private native void write0(int b) throws IOException;
528
529 /**
530 * Writes a sub array as a sequence of bytes.
531 * @param b the data to be written
532
533 * @param off the start offset in the data
534 * @param len the number of bytes that are written
535 * @exception IOException If an I/O error has occurred.
536 */
537 private native void writeBytes(byte b[], int off, int len) throws IOException;
538
539 /**
540 * Writes {@code b.length} bytes from the specified byte array
541 * to this file, starting at the current file pointer.
542 *
543 * @param b the data.
544 * @exception IOException if an I/O error occurs.
545 */
546 public void write(byte b[]) throws IOException {
547 writeBytes(b, 0, b.length);
548 }
549
550 /**
551 * Writes {@code len} bytes from the specified byte array
552 * starting at offset {@code off} to this file.
553 *
554 * @param b the data.
555 * @param off the start offset in the data.
556 * @param len the number of bytes to write.
557 * @exception IOException if an I/O error occurs.
558 */
559 public void write(byte b[], int off, int len) throws IOException {
560 writeBytes(b, off, len);
561 }
562
563 // 'Random access' stuff
564
565 /**
566 * Returns the current offset in this file.
567 *
568 * @return the offset from the beginning of the file, in bytes,
569 * at which the next read or write occurs.
570 * @exception IOException if an I/O error occurs.
571 */
572 public native long getFilePointer() throws IOException;
573
574 /**
575 * Sets the file-pointer offset, measured from the beginning of this
576 * file, at which the next read or write occurs. The offset may be
577 * set beyond the end of the file. Setting the offset beyond the end
578 * of the file does not change the file length. The file length will
579 * change only by writing after the offset has been set beyond the end
580 * of the file.
581 *
582 * @param pos the offset position, measured in bytes from the
583 * beginning of the file, at which to set the file
584 * pointer.
585 * @exception IOException if {@code pos} is less than
586 * {@code 0} or if an I/O error occurs.
587 */
588 public void seek(long pos) throws IOException {
589 if (pos < 0) {
590 throw new IOException("Negative seek offset");
591 } else {
592 seek0(pos);
593 }
594 }
595
596 private native void seek0(long pos) throws IOException;
597
598 /**
599 * Returns the length of this file.
600 *
601 * @return the length of this file, measured in bytes.
602 * @exception IOException if an I/O error occurs.
603 */
604 public native long length() throws IOException;
605
606 /**
607 * Sets the length of this file.
608 *
609 * <p> If the present length of the file as returned by the
610 * {@code length} method is greater than the {@code newLength}
611 * argument then the file will be truncated. In this case, if the file
612 * offset as returned by the {@code getFilePointer} method is greater
613 * than {@code newLength} then after this method returns the offset
614 * will be equal to {@code newLength}.
615 *
616 * <p> If the present length of the file as returned by the
617 * {@code length} method is smaller than the {@code newLength}
618 * argument then the file will be extended. In this case, the contents of
619 * the extended portion of the file are not defined.
620 *
621 * @param newLength The desired length of the file
622 * @exception IOException If an I/O error occurs
623 * @since 1.2
624 */
625 public native void setLength(long newLength) throws IOException;
626
627 /**
628 * Closes this random access file stream and releases any system
629 * resources associated with the stream. A closed random access
630 * file cannot perform input or output operations and cannot be
631 * reopened.
632 *
633 * <p> If this file has an associated channel then the channel is closed
634 * as well.
635 *
636 * @exception IOException if an I/O error occurs.
637 *
638 * @revised 1.4
639 * @spec JSR-51
640 */
641 public void close() throws IOException {
642 if (!closed.compareAndSet(false, true)) {
643 // if compareAndSet() returns false closed was already true
644 return;
645 }
646
647 FileChannel fc = channel;
648 if (fc != null) {
649 fc.close();
650 }
651
652 fd.closeAll(new Closeable() {
653 public void close() throws IOException {
654 fd.close();
655 }
656 });
657 }
658
659 //
660 // Some "reading/writing Java data types" methods stolen from
661 // DataInputStream and DataOutputStream.
662 //
663
664 /**
665 * Reads a {@code boolean} from this file. This method reads a
666 * single byte from the file, starting at the current file pointer.
667 * A value of {@code 0} represents
668 * {@code false}. Any other value represents {@code true}.
669 * This method blocks until the byte is read, the end of the stream
670 * is detected, or an exception is thrown.
671 *
672 * @return the {@code boolean} value read.
673 * @exception EOFException if this file has reached the end.
674 * @exception IOException if an I/O error occurs.
675 */
676 public final boolean readBoolean() throws IOException {
677 int ch = this.read();
678 if (ch < 0)
679 throw new EOFException();
680 return (ch != 0);
681 }
682
683 /**
684 * Reads a signed eight-bit value from this file. This method reads a
685 * byte from the file, starting from the current file pointer.
686 * If the byte read is {@code b}, where
687 * <code>0 <= b <= 255</code>,
688 * then the result is:
689 * <blockquote><pre>
690 * (byte)(b)
691 * </pre></blockquote>
692 * <p>
693 * This method blocks until the byte is read, the end of the stream
694 * is detected, or an exception is thrown.
695 *
696 * @return the next byte of this file as a signed eight-bit
697 * {@code byte}.
698 * @exception EOFException if this file has reached the end.
699 * @exception IOException if an I/O error occurs.
700 */
701 public final byte readByte() throws IOException {
702 int ch = this.read();
703 if (ch < 0)
704 throw new EOFException();
705 return (byte)(ch);
706 }
707
708 /**
709 * Reads an unsigned eight-bit number from this file. This method reads
710 * a byte from this file, starting at the current file pointer,
711 * and returns that byte.
712 * <p>
713 * This method blocks until the byte is read, the end of the stream
714 * is detected, or an exception is thrown.
715 *
716 * @return the next byte of this file, interpreted as an unsigned
717 * eight-bit number.
718 * @exception EOFException if this file has reached the end.
719 * @exception IOException if an I/O error occurs.
720 */
721 public final int readUnsignedByte() throws IOException {
722 int ch = this.read();
723 if (ch < 0)
724 throw new EOFException();
725 return ch;
726 }
727
728 /**
729 * Reads a signed 16-bit number from this file. The method reads two
730 * bytes from this file, starting at the current file pointer.
731 * If the two bytes read, in order, are
732 * {@code b1} and {@code b2}, where each of the two values is
733 * between {@code 0} and {@code 255}, inclusive, then the
734 * result is equal to:
735 * <blockquote><pre>
736 * (short)((b1 << 8) | b2)
737 * </pre></blockquote>
738 * <p>
739 * This method blocks until the two bytes are read, the end of the
740 * stream is detected, or an exception is thrown.
741 *
742 * @return the next two bytes of this file, interpreted as a signed
743 * 16-bit number.
744 * @exception EOFException if this file reaches the end before reading
745 * two bytes.
746 * @exception IOException if an I/O error occurs.
747 */
748 public final short readShort() throws IOException {
749 int ch1 = this.read();
750 int ch2 = this.read();
751 if ((ch1 | ch2) < 0)
752 throw new EOFException();
753 return (short)((ch1 << 8) + (ch2 << 0));
754 }
755
756 /**
757 * Reads an unsigned 16-bit number from this file. This method reads
758 * two bytes from the file, starting at the current file pointer.
759 * If the bytes read, in order, are
760 * {@code b1} and {@code b2}, where
761 * <code>0 <= b1, b2 <= 255</code>,
762 * then the result is equal to:
763 * <blockquote><pre>
764 * (b1 << 8) | b2
765 * </pre></blockquote>
766 * <p>
767 * This method blocks until the two bytes are read, the end of the
768 * stream is detected, or an exception is thrown.
769 *
770 * @return the next two bytes of this file, interpreted as an unsigned
771 * 16-bit integer.
772 * @exception EOFException if this file reaches the end before reading
773 * two bytes.
774 * @exception IOException if an I/O error occurs.
775 */
776 public final int readUnsignedShort() throws IOException {
777 int ch1 = this.read();
778 int ch2 = this.read();
779 if ((ch1 | ch2) < 0)
780 throw new EOFException();
781 return (ch1 << 8) + (ch2 << 0);
782 }
783
784 /**
785 * Reads a character from this file. This method reads two
786 * bytes from the file, starting at the current file pointer.
787 * If the bytes read, in order, are
788 * {@code b1} and {@code b2}, where
789 * <code>0 <= b1, b2 <= 255</code>,
790 * then the result is equal to:
791 * <blockquote><pre>
792 * (char)((b1 << 8) | b2)
793 * </pre></blockquote>
794 * <p>
795 * This method blocks until the two bytes are read, the end of the
796 * stream is detected, or an exception is thrown.
797 *
798 * @return the next two bytes of this file, interpreted as a
799 * {@code char}.
800 * @exception EOFException if this file reaches the end before reading
801 * two bytes.
802 * @exception IOException if an I/O error occurs.
803 */
804 public final char readChar() throws IOException {
805 int ch1 = this.read();
806 int ch2 = this.read();
807 if ((ch1 | ch2) < 0)
808 throw new EOFException();
809 return (char)((ch1 << 8) + (ch2 << 0));
810 }
811
812 /**
813 * Reads a signed 32-bit integer from this file. This method reads 4
814 * bytes from the file, starting at the current file pointer.
815 * If the bytes read, in order, are {@code b1},
816 * {@code b2}, {@code b3}, and {@code b4}, where
817 * <code>0 <= b1, b2, b3, b4 <= 255</code>,
818 * then the result is equal to:
819 * <blockquote><pre>
820 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
821 * </pre></blockquote>
822 * <p>
823 * This method blocks until the four bytes are read, the end of the
824 * stream is detected, or an exception is thrown.
825 *
826 * @return the next four bytes of this file, interpreted as an
827 * {@code int}.
828 * @exception EOFException if this file reaches the end before reading
829 * four bytes.
830 * @exception IOException if an I/O error occurs.
831 */
832 public final int readInt() throws IOException {
833 int ch1 = this.read();
834 int ch2 = this.read();
835 int ch3 = this.read();
836 int ch4 = this.read();
837 if ((ch1 | ch2 | ch3 | ch4) < 0)
838 throw new EOFException();
839 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
840 }
841
842 /**
843 * Reads a signed 64-bit integer from this file. This method reads eight
844 * bytes from the file, starting at the current file pointer.
845 * If the bytes read, in order, are
846 * {@code b1}, {@code b2}, {@code b3},
847 * {@code b4}, {@code b5}, {@code b6},
848 * {@code b7}, and {@code b8,} where:
849 * <blockquote><pre>
850 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
851 * </pre></blockquote>
852 * <p>
853 * then the result is equal to:
854 * <blockquote><pre>
855 * ((long)b1 << 56) + ((long)b2 << 48)
856 * + ((long)b3 << 40) + ((long)b4 << 32)
857 * + ((long)b5 << 24) + ((long)b6 << 16)
858 * + ((long)b7 << 8) + b8
859 * </pre></blockquote>
860 * <p>
861 * This method blocks until the eight bytes are read, the end of the
862 * stream is detected, or an exception is thrown.
863 *
864 * @return the next eight bytes of this file, interpreted as a
865 * {@code long}.
866 * @exception EOFException if this file reaches the end before reading
867 * eight bytes.
868 * @exception IOException if an I/O error occurs.
869 */
870 public final long readLong() throws IOException {
871 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
872 }
873
874 /**
875 * Reads a {@code float} from this file. This method reads an
876 * {@code int} value, starting at the current file pointer,
877 * as if by the {@code readInt} method
878 * and then converts that {@code int} to a {@code float}
879 * using the {@code intBitsToFloat} method in class
880 * {@code Float}.
881 * <p>
882 * This method blocks until the four bytes are read, the end of the
883 * stream is detected, or an exception is thrown.
884 *
885 * @return the next four bytes of this file, interpreted as a
886 * {@code float}.
887 * @exception EOFException if this file reaches the end before reading
888 * four bytes.
889 * @exception IOException if an I/O error occurs.
890 * @see java.io.RandomAccessFile#readInt()
891 * @see java.lang.Float#intBitsToFloat(int)
892 */
893 public final float readFloat() throws IOException {
894 return Float.intBitsToFloat(readInt());
895 }
896
897 /**
898 * Reads a {@code double} from this file. This method reads a
899 * {@code long} value, starting at the current file pointer,
900 * as if by the {@code readLong} method
901 * and then converts that {@code long} to a {@code double}
902 * using the {@code longBitsToDouble} method in
903 * class {@code Double}.
904 * <p>
905 * This method blocks until the eight bytes are read, the end of the
906 * stream is detected, or an exception is thrown.
907 *
908 * @return the next eight bytes of this file, interpreted as a
909 * {@code double}.
910 * @exception EOFException if this file reaches the end before reading
911 * eight bytes.
912 * @exception IOException if an I/O error occurs.
913 * @see java.io.RandomAccessFile#readLong()
914 * @see java.lang.Double#longBitsToDouble(long)
915 */
916 public final double readDouble() throws IOException {
917 return Double.longBitsToDouble(readLong());
918 }
919
920 /**
921 * Reads the next line of text from this file. This method successively
922 * reads bytes from the file, starting at the current file pointer,
923 * until it reaches a line terminator or the end
924 * of the file. Each byte is converted into a character by taking the
925 * byte's value for the lower eight bits of the character and setting the
926 * high eight bits of the character to zero. This method does not,
927 * therefore, support the full Unicode character set.
928 *
929 * <p> A line of text is terminated by a carriage-return character
930 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a
931 * carriage-return character immediately followed by a newline character,
932 * or the end of the file. Line-terminating characters are discarded and
933 * are not included as part of the string returned.
934 *
935 * <p> This method blocks until a newline character is read, a carriage
936 * return and the byte following it are read (to see if it is a newline),
937 * the end of the file is reached, or an exception is thrown.
938 *
939 * @return the next line of text from this file, or null if end
940 * of file is encountered before even one byte is read.
941 * @exception IOException if an I/O error occurs.
942 */
943
944 public final String readLine() throws IOException {
945 StringBuilder input = new StringBuilder();
946 int c = -1;
947 boolean eol = false;
948
949 while (!eol) {
950 switch (c = read()) {
951 case -1:
952 case '\n':
953 eol = true;
954 break;
955 case '\r':
956 eol = true;
957 long cur = getFilePointer();
958 if ((read()) != '\n') {
959 seek(cur);
960 }
961 break;
962 default:
963 input.append((char)c);
964 break;
965 }
966 }
967
968 if ((c == -1) && (input.length() == 0)) {
969 return null;
970 }
971 return input.toString();
972 }
973
974 /**
975 * Reads in a string from this file. The string has been encoded
976 * using a
977 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
978 * format.
979 * <p>
980 * The first two bytes are read, starting from the current file
981 * pointer, as if by
982 * {@code readUnsignedShort}. This value gives the number of
983 * following bytes that are in the encoded string, not
984 * the length of the resulting string. The following bytes are then
985 * interpreted as bytes encoding characters in the modified UTF-8 format
986 * and are converted into characters.
987 * <p>
988 * This method blocks until all the bytes are read, the end of the
989 * stream is detected, or an exception is thrown.
990 *
991 * @return a Unicode string.
992 * @exception EOFException if this file reaches the end before
993 * reading all the bytes.
994 * @exception IOException if an I/O error occurs.
995 * @exception UTFDataFormatException if the bytes do not represent
996 * valid modified UTF-8 encoding of a Unicode string.
997 * @see java.io.RandomAccessFile#readUnsignedShort()
998 */
999 public final String readUTF() throws IOException {
1000 return DataInputStream.readUTF(this);
1001 }
1002
1003 /**
1004 * Writes a {@code boolean} to the file as a one-byte value. The
1005 * value {@code true} is written out as the value
1006 * {@code (byte)1}; the value {@code false} is written out
1007 * as the value {@code (byte)0}. The write starts at
1008 * the current position of the file pointer.
1009 *
1010 * @param v a {@code boolean} value to be written.
1011 * @exception IOException if an I/O error occurs.
1012 */
1013 public final void writeBoolean(boolean v) throws IOException {
1014 write(v ? 1 : 0);
1015 //written++;
1016 }
1017
1018 /**
1019 * Writes a {@code byte} to the file as a one-byte value. The
1020 * write starts at the current position of the file pointer.
1021 *
1022 * @param v a {@code byte} value to be written.
1023 * @exception IOException if an I/O error occurs.
1024 */
1025 public final void writeByte(int v) throws IOException {
1026 write(v);
1027 //written++;
1028 }
1029
1030 /**
1031 * Writes a {@code short} to the file as two bytes, high byte first.
1032 * The write starts at the current position of the file pointer.
1033 *
1034 * @param v a {@code short} to be written.
1035 * @exception IOException if an I/O error occurs.
1036 */
1037 public final void writeShort(int v) throws IOException {
1038 write((v >>> 8) & 0xFF);
1039 write((v >>> 0) & 0xFF);
1040 //written += 2;
1041 }
1042
1043 /**
1044 * Writes a {@code char} to the file as a two-byte value, high
1045 * byte first. The write starts at the current position of the
1046 * file pointer.
1047 *
1048 * @param v a {@code char} value to be written.
1049 * @exception IOException if an I/O error occurs.
1050 */
1051 public final void writeChar(int v) throws IOException {
1052 write((v >>> 8) & 0xFF);
1053 write((v >>> 0) & 0xFF);
1054 //written += 2;
1055 }
1056
1057 /**
1058 * Writes an {@code int} to the file as four bytes, high byte first.
1059 * The write starts at the current position of the file pointer.
1060 *
1061 * @param v an {@code int} to be written.
1062 * @exception IOException if an I/O error occurs.
1063 */
1064 public final void writeInt(int v) throws IOException {
1065 write((v >>> 24) & 0xFF);
1066 write((v >>> 16) & 0xFF);
1067 write((v >>> 8) & 0xFF);
1068 write((v >>> 0) & 0xFF);
1069 //written += 4;
1070 }
1071
1072 /**
1073 * Writes a {@code long} to the file as eight bytes, high byte first.
1074 * The write starts at the current position of the file pointer.
1075 *
1076 * @param v a {@code long} to be written.
1077 * @exception IOException if an I/O error occurs.
1078 */
1079 public final void writeLong(long v) throws IOException {
1080 write((int)(v >>> 56) & 0xFF);
1081 write((int)(v >>> 48) & 0xFF);
1082 write((int)(v >>> 40) & 0xFF);
1083 write((int)(v >>> 32) & 0xFF);
1084 write((int)(v >>> 24) & 0xFF);
1085 write((int)(v >>> 16) & 0xFF);
1086 write((int)(v >>> 8) & 0xFF);
1087 write((int)(v >>> 0) & 0xFF);
1088 //written += 8;
1089 }
1090
1091 /**
1092 * Converts the float argument to an {@code int} using the
1093 * {@code floatToIntBits} method in class {@code Float},
1094 * and then writes that {@code int} value to the file as a
1095 * four-byte quantity, high byte first. The write starts at the
1096 * current position of the file pointer.
1097 *
1098 * @param v a {@code float} value to be written.
1099 * @exception IOException if an I/O error occurs.
1100 * @see java.lang.Float#floatToIntBits(float)
1101 */
1102 public final void writeFloat(float v) throws IOException {
1103 writeInt(Float.floatToIntBits(v));
1104 }
1105
1106 /**
1107 * Converts the double argument to a {@code long} using the
1108 * {@code doubleToLongBits} method in class {@code Double},
1109 * and then writes that {@code long} value to the file as an
1110 * eight-byte quantity, high byte first. The write starts at the current
1111 * position of the file pointer.
1112 *
1113 * @param v a {@code double} value to be written.
1114 * @exception IOException if an I/O error occurs.
1115 * @see java.lang.Double#doubleToLongBits(double)
1116 */
1117 public final void writeDouble(double v) throws IOException {
1118 writeLong(Double.doubleToLongBits(v));
1119 }
1120
1121 /**
1122 * Writes the string to the file as a sequence of bytes. Each
1123 * character in the string is written out, in sequence, by discarding
1124 * its high eight bits. The write starts at the current position of
1125 * the file pointer.
1126 *
1127 * @param s a string of bytes to be written.
1128 * @exception IOException if an I/O error occurs.
1129 */
1130 @SuppressWarnings("deprecation")
1131 public final void writeBytes(String s) throws IOException {
1132 int len = s.length();
1133 byte[] b = new byte[len];
1134 s.getBytes(0, len, b, 0);
1135 writeBytes(b, 0, len);
1136 }
1137
1138 /**
1139 * Writes a string to the file as a sequence of characters. Each
1140 * character is written to the data output stream as if by the
1141 * {@code writeChar} method. The write starts at the current
1142 * position of the file pointer.
1143 *
1144 * @param s a {@code String} value to be written.
1145 * @exception IOException if an I/O error occurs.
1146 * @see java.io.RandomAccessFile#writeChar(int)
1147 */
1148 public final void writeChars(String s) throws IOException {
1149 int clen = s.length();
1150 int blen = 2*clen;
1151 byte[] b = new byte[blen];
1152 char[] c = new char[clen];
1153 s.getChars(0, clen, c, 0);
1154 for (int i = 0, j = 0; i < clen; i++) {
1155 b[j++] = (byte)(c[i] >>> 8);
1156 b[j++] = (byte)(c[i] >>> 0);
1157 }
1158 writeBytes(b, 0, blen);
1159 }
1160
1161 /**
1162 * Writes a string to the file using
1163 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1164 * encoding in a machine-independent manner.
1165 * <p>
1166 * First, two bytes are written to the file, starting at the
1167 * current file pointer, as if by the
1168 * {@code writeShort} method giving the number of bytes to
1169 * follow. This value is the number of bytes actually written out,
1170 * not the length of the string. Following the length, each character
1171 * of the string is output, in sequence, using the modified UTF-8 encoding
1172 * for each character.
1173 *
1174 * @param str a string to be written.
1175 * @exception IOException if an I/O error occurs.
1176 */
1177 public final void writeUTF(String str) throws IOException {
1178 DataOutputStream.writeUTF(str, this);
1179 }
1180
1181 private static native void initIDs();
1182
1183 static {
1184 initIDs();
1185 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess()
1186 {
1187 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag
1188 // is only implemented/supported on windows.
1189 public RandomAccessFile openAndDelete(File file, String mode)
1190 throws IOException
1191 {
1192 return new RandomAccessFile(file, mode, true);
1193 }
1194 });
1195 }
1196 }