1 /*
2 * Copyright (c) 1994, 2017, 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 scope="col" style="text-align:left">Value</th><th scope="col" style="text-align:left">Meaning</th></tr>
143 * </thead>
144 * <tbody>
145 * <tr><th scope="row" style="vertical-align:top">{@code "r"}</th>
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><th scope="row" style="vertical-align:top">{@code "rw"}</th>
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><th scope="row" style="vertical-align:top">{@code "rws"}</th>
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><th scope="row" style="vertical-align:top">{@code "rwd"}</th>
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 FileCleanable.register(fd); // open sets the fd, register the cleanup
261 }
262
263 /**
264 * Returns the opaque file descriptor object associated with this
265 * stream.
266 *
267 * @return the file descriptor object associated with this stream.
268 * @exception IOException if an I/O error occurs.
269 * @see java.io.FileDescriptor
270 */
271 public final FileDescriptor getFD() throws IOException {
272 if (fd != null) {
273 return fd;
274 }
275 throw new IOException();
276 }
277
278 /**
279 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
280 * object associated with this file.
281 *
282 * <p> The {@link java.nio.channels.FileChannel#position()
283 * position} of the returned channel will always be equal to
284 * this object's file-pointer offset as returned by the {@link
285 * #getFilePointer getFilePointer} method. Changing this object's
286 * file-pointer offset, whether explicitly or by reading or writing bytes,
287 * will change the position of the channel, and vice versa. Changing the
288 * file's length via this object will change the length seen via the file
289 * channel, and vice versa.
290 *
291 * @return the file channel associated with this file
292 *
293 * @since 1.4
294 * @spec JSR-51
295 */
296 public final FileChannel getChannel() {
297 FileChannel fc = this.channel;
298 if (fc == null) {
299 synchronized (this) {
300 fc = this.channel;
301 if (fc == null) {
302 this.channel = fc = FileChannelImpl.open(fd, path, true,
303 rw, false, this);
304 if (closed.get()) {
305 try {
306 fc.close();
307 } catch (IOException ioe) {
308 throw new InternalError(ioe); // should not happen
309 }
310 }
311 }
312 }
313 }
314 return fc;
315 }
316
317 /**
318 * Opens a file and returns the file descriptor. The file is
319 * opened in read-write mode if the O_RDWR bit in {@code mode}
320 * is true, else the file is opened as read-only.
321 * If the {@code name} refers to a directory, an IOException
322 * is thrown.
323 *
324 * @param name the name of the file
325 * @param mode the mode flags, a combination of the O_ constants
326 * defined above
327 */
328 private native void open0(String name, int mode)
329 throws FileNotFoundException;
330
331 // wrap native call to allow instrumentation
332 /**
333 * Opens a file and returns the file descriptor. The file is
334 * opened in read-write mode if the O_RDWR bit in {@code mode}
335 * is true, else the file is opened as read-only.
336 * If the {@code name} refers to a directory, an IOException
337 * is thrown.
338 *
339 * @param name the name of the file
340 * @param mode the mode flags, a combination of the O_ constants
341 * defined above
342 */
343 private void open(String name, int mode)
344 throws FileNotFoundException {
345 open0(name, mode);
346 }
347
348 // 'Read' primitives
349
350 /**
351 * Reads a byte of data from this file. The byte is returned as an
352 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This
353 * method blocks if no input is yet available.
354 * <p>
355 * Although {@code RandomAccessFile} is not a subclass of
356 * {@code InputStream}, this method behaves in exactly the same
357 * way as the {@link InputStream#read()} method of
358 * {@code InputStream}.
359 *
360 * @return the next byte of data, or {@code -1} if the end of the
361 * file has been reached.
362 * @exception IOException if an I/O error occurs. Not thrown if
363 * end-of-file has been reached.
364 */
365 public int read() throws IOException {
366 return read0();
367 }
368
369 private native int read0() throws IOException;
370
371 /**
372 * Reads a sub array as a sequence of bytes.
373 * @param b the buffer into which the data is read.
374 * @param off the start offset of the data.
375 * @param len the number of bytes to read.
376 * @exception IOException If an I/O error has occurred.
377 */
378 private native int readBytes(byte b[], int off, int len) throws IOException;
379
380 /**
381 * Reads up to {@code len} bytes of data from this file into an
382 * array of bytes. This method blocks until at least one byte of input
383 * is available.
384 * <p>
385 * Although {@code RandomAccessFile} is not a subclass of
386 * {@code InputStream}, this method behaves in exactly the
387 * same way as the {@link InputStream#read(byte[], int, int)} method of
388 * {@code InputStream}.
389 *
390 * @param b the buffer into which the data is read.
391 * @param off the start offset in array {@code b}
392 * at which the data is written.
393 * @param len the maximum number of bytes read.
394 * @return the total number of bytes read into the buffer, or
395 * {@code -1} if there is no more data because the end of
396 * the file has been reached.
397 * @exception IOException If the first byte cannot be read for any reason
398 * other than end of file, or if the random access file has been closed, or if
399 * some other I/O error occurs.
400 * @exception NullPointerException If {@code b} is {@code null}.
401 * @exception IndexOutOfBoundsException If {@code off} is negative,
402 * {@code len} is negative, or {@code len} is greater than
403 * {@code b.length - off}
404 */
405 public int read(byte b[], int off, int len) throws IOException {
406 return readBytes(b, off, len);
407 }
408
409 /**
410 * Reads up to {@code b.length} bytes of data from this file
411 * into an array of bytes. This method blocks until at least one byte
412 * of input is available.
413 * <p>
414 * Although {@code RandomAccessFile} is not a subclass of
415 * {@code InputStream}, this method behaves in exactly the
416 * same way as the {@link InputStream#read(byte[])} method of
417 * {@code InputStream}.
418 *
419 * @param b the buffer into which the data is read.
420 * @return the total number of bytes read into the buffer, or
421 * {@code -1} if there is no more data because the end of
422 * this file has been reached.
423 * @exception IOException If the first byte cannot be read for any reason
424 * other than end of file, or if the random access file has been closed, or if
425 * some other I/O error occurs.
426 * @exception NullPointerException If {@code b} is {@code null}.
427 */
428 public int read(byte b[]) throws IOException {
429 return readBytes(b, 0, b.length);
430 }
431
432 /**
433 * Reads {@code b.length} bytes from this file into the byte
434 * array, starting at the current file pointer. This method reads
435 * repeatedly from the file until the requested number of bytes are
436 * read. This method blocks until the requested number of bytes are
437 * read, the end of the stream is detected, or an exception is thrown.
438 *
439 * @param b the buffer into which the data is read.
440 * @throws NullPointerException if {@code b} is {@code null}.
441 * @throws EOFException if this file reaches the end before reading
442 * all the bytes.
443 * @throws IOException if an I/O error occurs.
444 */
445 public final void readFully(byte b[]) throws IOException {
446 readFully(b, 0, b.length);
447 }
448
449 /**
450 * Reads exactly {@code len} bytes from this file into the byte
451 * array, starting at the current file pointer. This method reads
452 * repeatedly from the file until the requested number of bytes are
453 * read. This method blocks until the requested number of bytes are
454 * read, the end of the stream is detected, or an exception is thrown.
455 *
456 * @param b the buffer into which the data is read.
457 * @param off the start offset into the data array {@code b}.
458 * @param len the number of bytes to read.
459 * @throws NullPointerException if {@code b} is {@code null}.
460 * @throws IndexOutOfBoundsException if {@code off} is negative,
461 * {@code len} is negative, or {@code len} is greater than
462 * {@code b.length - off}.
463 * @throws EOFException if this file reaches the end before reading
464 * all the bytes.
465 * @throws IOException if an I/O error occurs.
466 */
467 public final void readFully(byte b[], int off, int len) throws IOException {
468 int n = 0;
469 do {
470 int count = this.read(b, off + n, len - n);
471 if (count < 0)
472 throw new EOFException();
473 n += count;
474 } while (n < len);
475 }
476
477 /**
478 * Attempts to skip over {@code n} bytes of input discarding the
479 * skipped bytes.
480 * <p>
481 *
482 * This method may skip over some smaller number of bytes, possibly zero.
483 * This may result from any of a number of conditions; reaching end of
484 * file before {@code n} bytes have been skipped is only one
485 * possibility. This method never throws an {@code EOFException}.
486 * The actual number of bytes skipped is returned. If {@code n}
487 * is negative, no bytes are skipped.
488 *
489 * @param n the number of bytes to be skipped.
490 * @return the actual number of bytes skipped.
491 * @exception IOException if an I/O error occurs.
492 */
493 public int skipBytes(int n) throws IOException {
494 long pos;
495 long len;
496 long newpos;
497
498 if (n <= 0) {
499 return 0;
500 }
501 pos = getFilePointer();
502 len = length();
503 newpos = pos + n;
504 if (newpos > len) {
505 newpos = len;
506 }
507 seek(newpos);
508
509 /* return the actual number of bytes skipped */
510 return (int) (newpos - pos);
511 }
512
513 // 'Write' primitives
514
515 /**
516 * Writes the specified byte to this file. The write starts at
517 * the current file pointer.
518 *
519 * @param b the {@code byte} to be written.
520 * @exception IOException if an I/O error occurs.
521 */
522 public void write(int b) throws IOException {
523 write0(b);
524 }
525
526 private native void write0(int b) throws IOException;
527
528 /**
529 * Writes a sub array as a sequence of bytes.
530 * @param b the data to be written
531
532 * @param off the start offset in the data
533 * @param len the number of bytes that are written
534 * @exception IOException If an I/O error has occurred.
535 */
536 private native void writeBytes(byte b[], int off, int len) throws IOException;
537
538 /**
539 * Writes {@code b.length} bytes from the specified byte array
540 * to this file, starting at the current file pointer.
541 *
542 * @param b the data.
543 * @exception IOException if an I/O error occurs.
544 */
545 public void write(byte b[]) throws IOException {
546 writeBytes(b, 0, b.length);
547 }
548
549 /**
550 * Writes {@code len} bytes from the specified byte array
551 * starting at offset {@code off} to this file.
552 *
553 * @param b the data.
554 * @param off the start offset in the data.
555 * @param len the number of bytes to write.
556 * @exception IOException if an I/O error occurs.
557 */
558 public void write(byte b[], int off, int len) throws IOException {
559 writeBytes(b, off, len);
560 }
561
562 // 'Random access' stuff
563
564 /**
565 * Returns the current offset in this file.
566 *
567 * @return the offset from the beginning of the file, in bytes,
568 * at which the next read or write occurs.
569 * @exception IOException if an I/O error occurs.
570 */
571 public native long getFilePointer() throws IOException;
572
573 /**
574 * Sets the file-pointer offset, measured from the beginning of this
575 * file, at which the next read or write occurs. The offset may be
576 * set beyond the end of the file. Setting the offset beyond the end
577 * of the file does not change the file length. The file length will
578 * change only by writing after the offset has been set beyond the end
579 * of the file.
580 *
581 * @param pos the offset position, measured in bytes from the
582 * beginning of the file, at which to set the file
583 * pointer.
584 * @exception IOException if {@code pos} is less than
585 * {@code 0} or if an I/O error occurs.
586 */
587 public void seek(long pos) throws IOException {
588 if (pos < 0) {
589 throw new IOException("Negative seek offset");
590 } else {
591 seek0(pos);
592 }
593 }
594
595 private native void seek0(long pos) throws IOException;
596
597 /**
598 * Returns the length of this file.
599 *
600 * @return the length of this file, measured in bytes.
601 * @exception IOException if an I/O error occurs.
602 */
603 public native long length() throws IOException;
604
605 /**
606 * Sets the length of this file.
607 *
608 * <p> If the present length of the file as returned by the
609 * {@code length} method is greater than the {@code newLength}
610 * argument then the file will be truncated. In this case, if the file
611 * offset as returned by the {@code getFilePointer} method is greater
612 * than {@code newLength} then after this method returns the offset
613 * will be equal to {@code newLength}.
614 *
615 * <p> If the present length of the file as returned by the
616 * {@code length} method is smaller than the {@code newLength}
617 * argument then the file will be extended. In this case, the contents of
618 * the extended portion of the file are not defined.
619 *
620 * @param newLength The desired length of the file
621 * @exception IOException If an I/O error occurs
622 * @since 1.2
623 */
624 public native void setLength(long newLength) throws IOException;
625
626 /**
627 * Closes this random access file stream and releases any system
628 * resources associated with the stream. A closed random access
629 * file cannot perform input or output operations and cannot be
630 * reopened.
631 *
632 * <p> If this file has an associated channel then the channel is closed
633 * as well.
634 *
635 * @exception IOException if an I/O error occurs.
636 *
637 * @revised 1.4
638 * @spec JSR-51
639 */
640 public void close() throws IOException {
641 if (!closed.compareAndSet(false, true)) {
642 // if compareAndSet() returns false closed was already true
643 return;
644 }
645
646 FileChannel fc = channel;
647 if (fc != null) {
648 fc.close();
649 }
650
651 fd.closeAll(new Closeable() {
652 public void close() throws IOException {
653 fd.close();
654 }
655 });
656 }
657
658 //
659 // Some "reading/writing Java data types" methods stolen from
660 // DataInputStream and DataOutputStream.
661 //
662
663 /**
664 * Reads a {@code boolean} from this file. This method reads a
665 * single byte from the file, starting at the current file pointer.
666 * A value of {@code 0} represents
667 * {@code false}. Any other value represents {@code true}.
668 * This method blocks until the byte is read, the end of the stream
669 * is detected, or an exception is thrown.
670 *
671 * @return the {@code boolean} value read.
672 * @exception EOFException if this file has reached the end.
673 * @exception IOException if an I/O error occurs.
674 */
675 public final boolean readBoolean() throws IOException {
676 int ch = this.read();
677 if (ch < 0)
678 throw new EOFException();
679 return (ch != 0);
680 }
681
682 /**
683 * Reads a signed eight-bit value from this file. This method reads a
684 * byte from the file, starting from the current file pointer.
685 * If the byte read is {@code b}, where
686 * <code>0 <= b <= 255</code>,
687 * then the result is:
688 * <blockquote><pre>
689 * (byte)(b)
690 * </pre></blockquote>
691 * <p>
692 * This method blocks until the byte is read, the end of the stream
693 * is detected, or an exception is thrown.
694 *
695 * @return the next byte of this file as a signed eight-bit
696 * {@code byte}.
697 * @exception EOFException if this file has reached the end.
698 * @exception IOException if an I/O error occurs.
699 */
700 public final byte readByte() throws IOException {
701 int ch = this.read();
702 if (ch < 0)
703 throw new EOFException();
704 return (byte)(ch);
705 }
706
707 /**
708 * Reads an unsigned eight-bit number from this file. This method reads
709 * a byte from this file, starting at the current file pointer,
710 * and returns that byte.
711 * <p>
712 * This method blocks until the byte is read, the end of the stream
713 * is detected, or an exception is thrown.
714 *
715 * @return the next byte of this file, interpreted as an unsigned
716 * eight-bit number.
717 * @exception EOFException if this file has reached the end.
718 * @exception IOException if an I/O error occurs.
719 */
720 public final int readUnsignedByte() throws IOException {
721 int ch = this.read();
722 if (ch < 0)
723 throw new EOFException();
724 return ch;
725 }
726
727 /**
728 * Reads a signed 16-bit number from this file. The method reads two
729 * bytes from this file, starting at the current file pointer.
730 * If the two bytes read, in order, are
731 * {@code b1} and {@code b2}, where each of the two values is
732 * between {@code 0} and {@code 255}, inclusive, then the
733 * result is equal to:
734 * <blockquote><pre>
735 * (short)((b1 << 8) | b2)
736 * </pre></blockquote>
737 * <p>
738 * This method blocks until the two bytes are read, the end of the
739 * stream is detected, or an exception is thrown.
740 *
741 * @return the next two bytes of this file, interpreted as a signed
742 * 16-bit number.
743 * @exception EOFException if this file reaches the end before reading
744 * two bytes.
745 * @exception IOException if an I/O error occurs.
746 */
747 public final short readShort() throws IOException {
748 int ch1 = this.read();
749 int ch2 = this.read();
750 if ((ch1 | ch2) < 0)
751 throw new EOFException();
752 return (short)((ch1 << 8) + (ch2 << 0));
753 }
754
755 /**
756 * Reads an unsigned 16-bit number from this file. This method reads
757 * two bytes from the file, starting at the current file pointer.
758 * If the bytes read, in order, are
759 * {@code b1} and {@code b2}, where
760 * <code>0 <= b1, b2 <= 255</code>,
761 * then the result is equal to:
762 * <blockquote><pre>
763 * (b1 << 8) | b2
764 * </pre></blockquote>
765 * <p>
766 * This method blocks until the two bytes are read, the end of the
767 * stream is detected, or an exception is thrown.
768 *
769 * @return the next two bytes of this file, interpreted as an unsigned
770 * 16-bit integer.
771 * @exception EOFException if this file reaches the end before reading
772 * two bytes.
773 * @exception IOException if an I/O error occurs.
774 */
775 public final int readUnsignedShort() throws IOException {
776 int ch1 = this.read();
777 int ch2 = this.read();
778 if ((ch1 | ch2) < 0)
779 throw new EOFException();
780 return (ch1 << 8) + (ch2 << 0);
781 }
782
783 /**
784 * Reads a character from this file. This method reads two
785 * bytes from the file, starting at the current file pointer.
786 * If the bytes read, in order, are
787 * {@code b1} and {@code b2}, where
788 * <code>0 <= b1, b2 <= 255</code>,
789 * then the result is equal to:
790 * <blockquote><pre>
791 * (char)((b1 << 8) | b2)
792 * </pre></blockquote>
793 * <p>
794 * This method blocks until the two bytes are read, the end of the
795 * stream is detected, or an exception is thrown.
796 *
797 * @return the next two bytes of this file, interpreted as a
798 * {@code char}.
799 * @exception EOFException if this file reaches the end before reading
800 * two bytes.
801 * @exception IOException if an I/O error occurs.
802 */
803 public final char readChar() throws IOException {
804 int ch1 = this.read();
805 int ch2 = this.read();
806 if ((ch1 | ch2) < 0)
807 throw new EOFException();
808 return (char)((ch1 << 8) + (ch2 << 0));
809 }
810
811 /**
812 * Reads a signed 32-bit integer from this file. This method reads 4
813 * bytes from the file, starting at the current file pointer.
814 * If the bytes read, in order, are {@code b1},
815 * {@code b2}, {@code b3}, and {@code b4}, where
816 * <code>0 <= b1, b2, b3, b4 <= 255</code>,
817 * then the result is equal to:
818 * <blockquote><pre>
819 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
820 * </pre></blockquote>
821 * <p>
822 * This method blocks until the four bytes are read, the end of the
823 * stream is detected, or an exception is thrown.
824 *
825 * @return the next four bytes of this file, interpreted as an
826 * {@code int}.
827 * @exception EOFException if this file reaches the end before reading
828 * four bytes.
829 * @exception IOException if an I/O error occurs.
830 */
831 public final int readInt() throws IOException {
832 int ch1 = this.read();
833 int ch2 = this.read();
834 int ch3 = this.read();
835 int ch4 = this.read();
836 if ((ch1 | ch2 | ch3 | ch4) < 0)
837 throw new EOFException();
838 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
839 }
840
841 /**
842 * Reads a signed 64-bit integer from this file. This method reads eight
843 * bytes from the file, starting at the current file pointer.
844 * If the bytes read, in order, are
845 * {@code b1}, {@code b2}, {@code b3},
846 * {@code b4}, {@code b5}, {@code b6},
847 * {@code b7}, and {@code b8,} where:
848 * <blockquote><pre>
849 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
850 * </pre></blockquote>
851 * <p>
852 * then the result is equal to:
853 * <blockquote><pre>
854 * ((long)b1 << 56) + ((long)b2 << 48)
855 * + ((long)b3 << 40) + ((long)b4 << 32)
856 * + ((long)b5 << 24) + ((long)b6 << 16)
857 * + ((long)b7 << 8) + b8
858 * </pre></blockquote>
859 * <p>
860 * This method blocks until the eight bytes are read, the end of the
861 * stream is detected, or an exception is thrown.
862 *
863 * @return the next eight bytes of this file, interpreted as a
864 * {@code long}.
865 * @exception EOFException if this file reaches the end before reading
866 * eight bytes.
867 * @exception IOException if an I/O error occurs.
868 */
869 public final long readLong() throws IOException {
870 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
871 }
872
873 /**
874 * Reads a {@code float} from this file. This method reads an
875 * {@code int} value, starting at the current file pointer,
876 * as if by the {@code readInt} method
877 * and then converts that {@code int} to a {@code float}
878 * using the {@code intBitsToFloat} method in class
879 * {@code Float}.
880 * <p>
881 * This method blocks until the four bytes are read, the end of the
882 * stream is detected, or an exception is thrown.
883 *
884 * @return the next four bytes of this file, interpreted as a
885 * {@code float}.
886 * @exception EOFException if this file reaches the end before reading
887 * four bytes.
888 * @exception IOException if an I/O error occurs.
889 * @see java.io.RandomAccessFile#readInt()
890 * @see java.lang.Float#intBitsToFloat(int)
891 */
892 public final float readFloat() throws IOException {
893 return Float.intBitsToFloat(readInt());
894 }
895
896 /**
897 * Reads a {@code double} from this file. This method reads a
898 * {@code long} value, starting at the current file pointer,
899 * as if by the {@code readLong} method
900 * and then converts that {@code long} to a {@code double}
901 * using the {@code longBitsToDouble} method in
902 * class {@code Double}.
903 * <p>
904 * This method blocks until the eight bytes are read, the end of the
905 * stream is detected, or an exception is thrown.
906 *
907 * @return the next eight bytes of this file, interpreted as a
908 * {@code double}.
909 * @exception EOFException if this file reaches the end before reading
910 * eight bytes.
911 * @exception IOException if an I/O error occurs.
912 * @see java.io.RandomAccessFile#readLong()
913 * @see java.lang.Double#longBitsToDouble(long)
914 */
915 public final double readDouble() throws IOException {
916 return Double.longBitsToDouble(readLong());
917 }
918
919 /**
920 * Reads the next line of text from this file. This method successively
921 * reads bytes from the file, starting at the current file pointer,
922 * until it reaches a line terminator or the end
923 * of the file. Each byte is converted into a character by taking the
924 * byte's value for the lower eight bits of the character and setting the
925 * high eight bits of the character to zero. This method does not,
926 * therefore, support the full Unicode character set.
927 *
928 * <p> A line of text is terminated by a carriage-return character
929 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a
930 * carriage-return character immediately followed by a newline character,
931 * or the end of the file. Line-terminating characters are discarded and
932 * are not included as part of the string returned.
933 *
934 * <p> This method blocks until a newline character is read, a carriage
935 * return and the byte following it are read (to see if it is a newline),
936 * the end of the file is reached, or an exception is thrown.
937 *
938 * @return the next line of text from this file, or null if end
939 * of file is encountered before even one byte is read.
940 * @exception IOException if an I/O error occurs.
941 */
942
943 public final String readLine() throws IOException {
944 StringBuilder input = new StringBuilder();
945 int c = -1;
946 boolean eol = false;
947
948 while (!eol) {
949 switch (c = read()) {
950 case -1:
951 case '\n':
952 eol = true;
953 break;
954 case '\r':
955 eol = true;
956 long cur = getFilePointer();
957 if ((read()) != '\n') {
958 seek(cur);
959 }
960 break;
961 default:
962 input.append((char)c);
963 break;
964 }
965 }
966
967 if ((c == -1) && (input.length() == 0)) {
968 return null;
969 }
970 return input.toString();
971 }
972
973 /**
974 * Reads in a string from this file. The string has been encoded
975 * using a
976 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
977 * format.
978 * <p>
979 * The first two bytes are read, starting from the current file
980 * pointer, as if by
981 * {@code readUnsignedShort}. This value gives the number of
982 * following bytes that are in the encoded string, not
983 * the length of the resulting string. The following bytes are then
984 * interpreted as bytes encoding characters in the modified UTF-8 format
985 * and are converted into characters.
986 * <p>
987 * This method blocks until all the bytes are read, the end of the
988 * stream is detected, or an exception is thrown.
989 *
990 * @return a Unicode string.
991 * @exception EOFException if this file reaches the end before
992 * reading all the bytes.
993 * @exception IOException if an I/O error occurs.
994 * @exception UTFDataFormatException if the bytes do not represent
995 * valid modified UTF-8 encoding of a Unicode string.
996 * @see java.io.RandomAccessFile#readUnsignedShort()
997 */
998 public final String readUTF() throws IOException {
999 return DataInputStream.readUTF(this);
1000 }
1001
1002 /**
1003 * Writes a {@code boolean} to the file as a one-byte value. The
1004 * value {@code true} is written out as the value
1005 * {@code (byte)1}; the value {@code false} is written out
1006 * as the value {@code (byte)0}. The write starts at
1007 * the current position of the file pointer.
1008 *
1009 * @param v a {@code boolean} value to be written.
1010 * @exception IOException if an I/O error occurs.
1011 */
1012 public final void writeBoolean(boolean v) throws IOException {
1013 write(v ? 1 : 0);
1014 //written++;
1015 }
1016
1017 /**
1018 * Writes a {@code byte} to the file as a one-byte value. The
1019 * write starts at the current position of the file pointer.
1020 *
1021 * @param v a {@code byte} value to be written.
1022 * @exception IOException if an I/O error occurs.
1023 */
1024 public final void writeByte(int v) throws IOException {
1025 write(v);
1026 //written++;
1027 }
1028
1029 /**
1030 * Writes a {@code short} to the file as two bytes, high byte first.
1031 * The write starts at the current position of the file pointer.
1032 *
1033 * @param v a {@code short} to be written.
1034 * @exception IOException if an I/O error occurs.
1035 */
1036 public final void writeShort(int v) throws IOException {
1037 write((v >>> 8) & 0xFF);
1038 write((v >>> 0) & 0xFF);
1039 //written += 2;
1040 }
1041
1042 /**
1043 * Writes a {@code char} to the file as a two-byte value, high
1044 * byte first. The write starts at the current position of the
1045 * file pointer.
1046 *
1047 * @param v a {@code char} value to be written.
1048 * @exception IOException if an I/O error occurs.
1049 */
1050 public final void writeChar(int v) throws IOException {
1051 write((v >>> 8) & 0xFF);
1052 write((v >>> 0) & 0xFF);
1053 //written += 2;
1054 }
1055
1056 /**
1057 * Writes an {@code int} to the file as four bytes, high byte first.
1058 * The write starts at the current position of the file pointer.
1059 *
1060 * @param v an {@code int} to be written.
1061 * @exception IOException if an I/O error occurs.
1062 */
1063 public final void writeInt(int v) throws IOException {
1064 write((v >>> 24) & 0xFF);
1065 write((v >>> 16) & 0xFF);
1066 write((v >>> 8) & 0xFF);
1067 write((v >>> 0) & 0xFF);
1068 //written += 4;
1069 }
1070
1071 /**
1072 * Writes a {@code long} to the file as eight bytes, high byte first.
1073 * The write starts at the current position of the file pointer.
1074 *
1075 * @param v a {@code long} to be written.
1076 * @exception IOException if an I/O error occurs.
1077 */
1078 public final void writeLong(long v) throws IOException {
1079 write((int)(v >>> 56) & 0xFF);
1080 write((int)(v >>> 48) & 0xFF);
1081 write((int)(v >>> 40) & 0xFF);
1082 write((int)(v >>> 32) & 0xFF);
1083 write((int)(v >>> 24) & 0xFF);
1084 write((int)(v >>> 16) & 0xFF);
1085 write((int)(v >>> 8) & 0xFF);
1086 write((int)(v >>> 0) & 0xFF);
1087 //written += 8;
1088 }
1089
1090 /**
1091 * Converts the float argument to an {@code int} using the
1092 * {@code floatToIntBits} method in class {@code Float},
1093 * and then writes that {@code int} value to the file as a
1094 * four-byte quantity, high byte first. The write starts at the
1095 * current position of the file pointer.
1096 *
1097 * @param v a {@code float} value to be written.
1098 * @exception IOException if an I/O error occurs.
1099 * @see java.lang.Float#floatToIntBits(float)
1100 */
1101 public final void writeFloat(float v) throws IOException {
1102 writeInt(Float.floatToIntBits(v));
1103 }
1104
1105 /**
1106 * Converts the double argument to a {@code long} using the
1107 * {@code doubleToLongBits} method in class {@code Double},
1108 * and then writes that {@code long} value to the file as an
1109 * eight-byte quantity, high byte first. The write starts at the current
1110 * position of the file pointer.
1111 *
1112 * @param v a {@code double} value to be written.
1113 * @exception IOException if an I/O error occurs.
1114 * @see java.lang.Double#doubleToLongBits(double)
1115 */
1116 public final void writeDouble(double v) throws IOException {
1117 writeLong(Double.doubleToLongBits(v));
1118 }
1119
1120 /**
1121 * Writes the string to the file as a sequence of bytes. Each
1122 * character in the string is written out, in sequence, by discarding
1123 * its high eight bits. The write starts at the current position of
1124 * the file pointer.
1125 *
1126 * @param s a string of bytes to be written.
1127 * @exception IOException if an I/O error occurs.
1128 */
1129 @SuppressWarnings("deprecation")
1130 public final void writeBytes(String s) throws IOException {
1131 int len = s.length();
1132 byte[] b = new byte[len];
1133 s.getBytes(0, len, b, 0);
1134 writeBytes(b, 0, len);
1135 }
1136
1137 /**
1138 * Writes a string to the file as a sequence of characters. Each
1139 * character is written to the data output stream as if by the
1140 * {@code writeChar} method. The write starts at the current
1141 * position of the file pointer.
1142 *
1143 * @param s a {@code String} value to be written.
1144 * @exception IOException if an I/O error occurs.
1145 * @see java.io.RandomAccessFile#writeChar(int)
1146 */
1147 public final void writeChars(String s) throws IOException {
1148 int clen = s.length();
1149 int blen = 2*clen;
1150 byte[] b = new byte[blen];
1151 char[] c = new char[clen];
1152 s.getChars(0, clen, c, 0);
1153 for (int i = 0, j = 0; i < clen; i++) {
1154 b[j++] = (byte)(c[i] >>> 8);
1155 b[j++] = (byte)(c[i] >>> 0);
1156 }
1157 writeBytes(b, 0, blen);
1158 }
1159
1160 /**
1161 * Writes a string to the file using
1162 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1163 * encoding in a machine-independent manner.
1164 * <p>
1165 * First, two bytes are written to the file, starting at the
1166 * current file pointer, as if by the
1167 * {@code writeShort} method giving the number of bytes to
1168 * follow. This value is the number of bytes actually written out,
1169 * not the length of the string. Following the length, each character
1170 * of the string is output, in sequence, using the modified UTF-8 encoding
1171 * for each character.
1172 *
1173 * @param str a string to be written.
1174 * @exception IOException if an I/O error occurs.
1175 */
1176 public final void writeUTF(String str) throws IOException {
1177 DataOutputStream.writeUTF(str, this);
1178 }
1179
1180 private static native void initIDs();
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 }
1196