1 /*
2 * Copyright (c) 1994, 2024, 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
30 import jdk.internal.access.JavaIORandomAccessFileAccess;
31 import jdk.internal.access.SharedSecrets;
32 import jdk.internal.misc.Blocker;
33 import jdk.internal.util.ByteArray;
34 import sun.nio.ch.FileChannelImpl;
35
36
37 /**
38 * Instances of this class support both reading and writing to a
39 * random access file. A random access file behaves like a large
40 * array of bytes stored in the file system. There is a kind of cursor,
41 * or index into the implied array, called the <em>file pointer</em>;
42 * input operations read bytes starting at the file pointer and advance
43 * the file pointer past the bytes read. If the random access file is
44 * created in read/write mode, then output operations are also available;
45 * output operations write bytes starting at the file pointer and advance
46 * the file pointer past the bytes written. Output operations that write
47 * past the current end of the implied array cause the array to be
48 * extended. The file pointer can be read by the
49 * {@code getFilePointer} method and set by the {@code seek}
50 * method.
51 * <p>
52 * It is generally true of all the reading routines in this class that
53 * if end-of-file is reached before the desired number of bytes has been
54 * read, an {@code EOFException} (which is a kind of
55 * {@code IOException}) is thrown. If any byte cannot be read for
56 * any reason other than end-of-file, an {@code IOException} other
57 * than {@code EOFException} is thrown. In particular, an
58 * {@code IOException} may be thrown if the stream has been closed.
59 *
60 * @since 1.0
61 */
62
63 public class RandomAccessFile implements DataOutput, DataInput, Closeable {
64
65 private static final int O_RDONLY = 1;
66 private static final int O_RDWR = 2;
67 private static final int O_SYNC = 4;
68 private static final int O_DSYNC = 8;
69 private static final int O_TEMPORARY = 16;
70
71 private final FileDescriptor fd;
72
73 private final boolean rw;
74
75 /**
76 * The path of the referenced file
77 * (null if the stream is created with a file descriptor)
78 */
79 private final String path;
80
81 private final Object closeLock = new Object();
82
83 /**
84 * A local buffer that allows reading and writing of
85 * longer primitive parameters (e.g. long) to be performed
86 * using bulk operations rather than on a per-byte basis.
87 */
88 private final byte[] buffer = new byte[Long.BYTES];
89
90 private volatile FileChannel channel;
91 private volatile boolean closed;
92
93 /**
94 * Creates a random access file stream to read from, and optionally
95 * to write to, a file with the specified pathname. A new
96 * {@link FileDescriptor} object is created to represent the
97 * connection to the file.
98 *
99 * <p> The {@code mode} argument specifies the access mode with which the
100 * file is to be opened. The permitted values and their meanings are as
101 * specified for the <a
102 * href="#mode">{@code RandomAccessFile(File,String)}</a> constructor.
103 *
104 * <p>
105 * If there is a security manager, its {@code checkRead} method
106 * is called with the {@code pathname} argument
107 * as its argument to see if read access to the file is allowed.
108 * If the mode allows writing, the security manager's
109 * {@code checkWrite} method
110 * is also called with the {@code pathname} argument
111 * as its argument to see if write access to the file is allowed.
112 *
113 * @param pathname the system-dependent pathname string
114 * @param mode the access <a href="#mode">mode</a>
115 * @throws IllegalArgumentException if the mode argument is not equal
116 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
117 * {@code "rwd"}
118 * @throws FileNotFoundException
119 * if the mode is {@code "r"} but the given pathname string does not
120 * denote an existing regular file, or if the mode begins with
121 * {@code "rw"} but the given pathname string does not denote an
122 * existing, writable regular file and a new regular file of
123 * that pathname cannot be created, or if some other error
124 * occurs while opening or creating the file
125 * @throws SecurityException if a security manager exists and its
126 * {@code checkRead} method denies read access to the file
127 * or the mode is {@code "rw"} and the security manager's
128 * {@code checkWrite} method denies write access to the file
129 * @see java.lang.SecurityException
130 * @see java.lang.SecurityManager#checkRead(java.lang.String)
131 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
132 */
133 public RandomAccessFile(String pathname, String mode)
134 throws FileNotFoundException
135 {
136 this(pathname != null ? new File(pathname) : null, mode);
137 }
138
139 /**
140 * Creates a random access file stream to read from, and optionally to
141 * write to, the file specified by the {@link File} argument. A new {@link
142 * FileDescriptor} object is created to represent this file connection.
143 *
144 * <p>The <a id="mode">{@code mode}</a> argument specifies the access mode
145 * in which the file is to be opened. The permitted values and their
146 * meanings are:
147 *
148 * <table class="striped">
149 * <caption style="display:none">Access mode permitted values and meanings</caption>
150 * <thead>
151 * <tr><th scope="col" style="text-align:left">Value</th><th scope="col" style="text-align:left">Meaning</th></tr>
152 * </thead>
153 * <tbody>
154 * <tr><th scope="row" style="vertical-align:top">{@code "r"}</th>
155 * <td> Open for reading only. Invoking any of the {@code write}
156 * methods of the resulting object will cause an
157 * {@link java.io.IOException} to be thrown.</td></tr>
158 * <tr><th scope="row" style="vertical-align:top">{@code "rw"}</th>
159 * <td> Open for reading and writing. If the file does not already
160 * exist then an attempt will be made to create it.</td></tr>
161 * <tr><th scope="row" style="vertical-align:top">{@code "rws"}</th>
162 * <td> Open for reading and writing, as with {@code "rw"}, and also
163 * require that every update to the file's content or metadata be
164 * written synchronously to the underlying storage device.</td></tr>
165 * <tr><th scope="row" style="vertical-align:top">{@code "rwd"}</th>
166 * <td> Open for reading and writing, as with {@code "rw"}, and also
167 * require that every update to the file's content be written
168 * synchronously to the underlying storage device.</td></tr>
169 * </tbody>
170 * </table>
171 *
172 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link
173 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of
174 * the {@link java.nio.channels.FileChannel} class, passing arguments of
175 * {@code true} and {@code false}, respectively, except that they always
176 * apply to every I/O operation and are therefore often more efficient. If
177 * the file resides on a local storage device then when an invocation of a
178 * method of this class returns it is guaranteed that all changes made to
179 * the file by that invocation will have been written to that device. This
180 * is useful for ensuring that critical information is not lost in the
181 * event of a system crash. If the file does not reside on a local device
182 * then no such guarantee is made.
183 *
184 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O
185 * operations performed. Using {@code "rwd"} only requires updates to the
186 * file's content to be written to storage; using {@code "rws"} requires
187 * updates to both the file's content and its metadata to be written, which
188 * generally requires at least one more low-level I/O operation.
189 *
190 * <p>If there is a security manager, its {@code checkRead} method is
191 * called with the pathname of the {@code file} argument as its
192 * argument to see if read access to the file is allowed. If the mode
193 * allows writing, the security manager's {@code checkWrite} method is
194 * also called with the pathname of the {@code file} argument to see if
195 * write access to the file is allowed.
196 *
197 * @param file the file object
198 * @param mode the access mode, as described
199 * <a href="#mode">above</a>
200 * @throws IllegalArgumentException if the mode argument is not equal
201 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or
202 * {@code "rwd"}
203 * @throws FileNotFoundException
204 * if the mode is {@code "r"} but the given file object does
205 * not denote an existing regular file, or if the mode begins
206 * with {@code "rw"} but the given file object does not denote
207 * an existing, writable regular file and a new regular file of
208 * that pathname cannot be created, or if some other error
209 * occurs while opening or creating the file
210 * @throws SecurityException if a security manager exists and its
211 * {@code checkRead} method denies read access to the file
212 * or the mode is {@code "rw"} and the security manager's
213 * {@code checkWrite} method denies write access to the file
214 * @see java.lang.SecurityManager#checkRead(java.lang.String)
215 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
216 * @see java.nio.channels.FileChannel#force(boolean)
217 */
218 @SuppressWarnings("this-escape")
219 public RandomAccessFile(File file, String mode)
220 throws FileNotFoundException
221 {
222 this(file, mode, false);
223 }
224
225 private RandomAccessFile(File file, String mode, boolean openAndDelete)
226 throws FileNotFoundException
227 {
228 String name = (file != null ? file.getPath() : null);
229 int imode = -1;
230
231 boolean rw = false;
232 if (mode.equals("r"))
233 imode = O_RDONLY;
234 else if (mode.startsWith("rw")) {
235 imode = O_RDWR;
236 rw = true;
237 if (mode.length() > 2) {
238 if (mode.equals("rws"))
239 imode |= O_SYNC;
240 else if (mode.equals("rwd"))
241 imode |= O_DSYNC;
242 else
243 imode = -1;
244 }
245 }
246 this.rw = rw;
247
248 if (openAndDelete)
249 imode |= O_TEMPORARY;
250 if (imode < 0)
251 throw new IllegalArgumentException("Illegal mode \"" + mode
252 + "\" must be one of "
253 + "\"r\", \"rw\", \"rws\","
254 + " or \"rwd\"");
255 @SuppressWarnings("removal")
256 SecurityManager security = System.getSecurityManager();
257 if (security != null) {
258 security.checkRead(name);
259 if (rw) {
260 security.checkWrite(name);
261 }
262 }
263 if (name == null) {
264 throw new NullPointerException();
265 }
266 if (file.isInvalid()) {
267 throw new FileNotFoundException("Invalid file path");
268 }
269 fd = new FileDescriptor();
270 fd.attach(this);
271 path = name;
272 open(name, imode);
273 FileCleanable.register(fd); // open sets the fd, register the cleanup
274 }
275
276 /**
277 * Returns the opaque file descriptor object associated with this
278 * stream.
279 *
280 * @return the file descriptor object associated with this stream.
281 * @throws IOException if an I/O error occurs.
282 * @see java.io.FileDescriptor
283 */
284 public final FileDescriptor getFD() throws IOException {
285 return fd;
286 }
287
288 /**
289 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
290 * object associated with this file.
291 *
292 * <p> The {@link java.nio.channels.FileChannel#position()
293 * position} of the returned channel will always be equal to
294 * this object's file-pointer offset as returned by the {@link
295 * #getFilePointer getFilePointer} method. Changing this object's
296 * file-pointer offset, whether explicitly or by reading or writing bytes,
297 * will change the position of the channel, and vice versa. Changing the
298 * file's length via this object will change the length seen via the file
299 * channel, and vice versa.
300 *
301 * @return the file channel associated with this file
302 *
303 * @since 1.4
304 */
305 public final FileChannel getChannel() {
306 FileChannel fc = this.channel;
307 if (fc == null) {
308 synchronized (this) {
309 fc = this.channel;
310 if (fc == null) {
311 this.channel = fc = FileChannelImpl.open(fd, path, true,
312 rw, false, this);
313 if (closed) {
314 try {
315 fc.close();
316 } catch (IOException ioe) {
317 throw new InternalError(ioe); // should not happen
318 }
319 }
320 }
321 }
322 }
323 return fc;
324 }
325
326 /**
327 * Opens a file and returns the file descriptor. The file is
328 * opened in read-write mode if the O_RDWR bit in {@code mode}
329 * is true, else the file is opened as read-only.
330 * If the {@code name} refers to a directory, an IOException
331 * is thrown.
332 *
333 * @param name the name of the file
334 * @param mode the mode flags, a combination of the O_ constants
335 * defined above
336 */
337 private native void open0(String name, int mode)
338 throws FileNotFoundException;
339
340 // wrap native call to allow instrumentation
341 /**
342 * Opens a file and returns the file descriptor. The file is
343 * opened in read-write mode if the O_RDWR bit in {@code mode}
344 * is true, else the file is opened as read-only.
345 * If the {@code name} refers to a directory, an IOException
346 * is thrown.
347 *
348 * @param name the name of the file
349 * @param mode the mode flags, a combination of the O_ constants
350 * defined above
351 */
352 private void open(String name, int mode) throws FileNotFoundException {
353 long comp = Blocker.begin();
354 try {
355 open0(name, mode);
356 } finally {
357 Blocker.end(comp);
358 }
359 }
360
361 // 'Read' primitives
362
363 /**
364 * Reads a byte of data from this file. The byte is returned as an
365 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This
366 * method blocks if no input is yet available.
367 * <p>
368 * Although {@code RandomAccessFile} is not a subclass of
369 * {@code InputStream}, this method behaves in exactly the same
370 * way as the {@link InputStream#read()} method of
371 * {@code InputStream}.
372 *
373 * @return the next byte of data, or {@code -1} if the end of the
374 * file has been reached.
375 * @throws IOException if an I/O error occurs. Not thrown if
376 * end-of-file has been reached.
377 */
378 public int read() throws IOException {
379 long comp = Blocker.begin();
380 try {
381 return read0();
382 } finally {
383 Blocker.end(comp);
384 }
385 }
386
387 private native int read0() throws IOException;
388
389 /**
390 * Reads a sub array as a sequence of bytes.
391 * @param b the buffer into which the data is read.
392 * @param off the start offset of the data.
393 * @param len the number of bytes to read.
394 * @throws IOException If an I/O error has occurred.
395 */
396 private int readBytes(byte[] b, int off, int len) throws IOException {
397 long comp = Blocker.begin();
398 try {
399 return readBytes0(b, off, len);
400 } finally {
401 Blocker.end(comp);
402 }
403 }
404
405 private native int readBytes0(byte[] b, int off, int len) throws IOException;
406
407 /**
408 * Reads up to {@code len} bytes of data from this file into an
409 * array of bytes. This method blocks until at least one byte of input
410 * 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[], int, int)} method of
415 * {@code InputStream}.
416 *
417 * @param b the buffer into which the data is read.
418 * @param off the start offset in array {@code b}
419 * at which the data is written.
420 * @param len the maximum number of bytes 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 * the file has been reached.
424 * @throws 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,
426 * or if some other I/O error occurs.
427 * @throws NullPointerException If {@code b} is {@code null}.
428 * @throws IndexOutOfBoundsException If {@code off} is negative,
429 * {@code len} is negative, or {@code len} is greater than
430 * {@code b.length - off}
431 */
432 public int read(byte[] b, int off, int len) throws IOException {
433 return readBytes(b, off, len);
434 }
435
436 /**
437 * Reads up to {@code b.length} bytes of data from this file
438 * into an array of bytes. This method blocks until at least one byte
439 * of input is available.
440 * <p>
441 * Although {@code RandomAccessFile} is not a subclass of
442 * {@code InputStream}, this method behaves in exactly the
443 * same way as the {@link InputStream#read(byte[])} method of
444 * {@code InputStream}.
445 *
446 * @param b the buffer into which the data is read.
447 * @return the total number of bytes read into the buffer, or
448 * {@code -1} if there is no more data because the end of
449 * this file has been reached.
450 * @throws IOException If the first byte cannot be read for any reason
451 * other than end of file, or if the random access file has been closed,
452 * or if some other I/O error occurs.
453 * @throws NullPointerException If {@code b} is {@code null}.
454 */
455 public int read(byte[] b) throws IOException {
456 return readBytes(b, 0, b.length);
457 }
458
459 /**
460 * Reads {@code b.length} bytes from this file into the byte
461 * array, starting at the current file pointer. This method reads
462 * repeatedly from the file until the requested number of bytes are
463 * read. This method blocks until the requested number of bytes are
464 * read, the end of the stream is detected, or an exception is thrown.
465 *
466 * @param b the buffer into which the data is read.
467 * @throws NullPointerException if {@code b} is {@code null}.
468 * @throws EOFException if this file reaches the end before reading
469 * all the bytes.
470 * @throws IOException if an I/O error occurs.
471 */
472 public final void readFully(byte[] b) throws IOException {
473 readFully(b, 0, b.length);
474 }
475
476 /**
477 * Reads exactly {@code len} bytes from this file into the byte
478 * array, starting at the current file pointer. This method reads
479 * repeatedly from the file until the requested number of bytes are
480 * read. This method blocks until the requested number of bytes are
481 * read, the end of the stream is detected, or an exception is thrown.
482 *
483 * @param b the buffer into which the data is read.
484 * @param off the start offset into the data array {@code b}.
485 * @param len the number of bytes to read.
486 * @throws NullPointerException if {@code b} is {@code null}.
487 * @throws IndexOutOfBoundsException if {@code off} is negative,
488 * {@code len} is negative, or {@code len} is greater than
489 * {@code b.length - off}.
490 * @throws EOFException if this file reaches the end before reading
491 * all the bytes.
492 * @throws IOException if an I/O error occurs.
493 */
494 public final void readFully(byte[] b, int off, int len) throws IOException {
495 int n = 0;
496 do {
497 int count = this.read(b, off + n, len - n);
498 if (count < 0)
499 throw new EOFException();
500 n += count;
501 } while (n < len);
502 }
503
504 /**
505 * Attempts to skip over {@code n} bytes of input discarding the
506 * skipped bytes.
507 * <p>
508 *
509 * This method may skip over some smaller number of bytes, possibly zero.
510 * This may result from any of a number of conditions; reaching end of
511 * file before {@code n} bytes have been skipped is only one
512 * possibility. This method never throws an {@code EOFException}.
513 * The actual number of bytes skipped is returned. If {@code n}
514 * is negative, no bytes are skipped.
515 *
516 * @param n the number of bytes to be skipped.
517 * @return the actual number of bytes skipped.
518 * @throws IOException if an I/O error occurs.
519 */
520 public int skipBytes(int n) throws IOException {
521 long pos;
522 long len;
523 long newpos;
524
525 if (n <= 0) {
526 return 0;
527 }
528 pos = getFilePointer();
529 len = length();
530 newpos = pos + n;
531 if (newpos > len) {
532 newpos = len;
533 }
534 seek(newpos);
535
536 /* return the actual number of bytes skipped */
537 return (int) (newpos - pos);
538 }
539
540 // 'Write' primitives
541
542 /**
543 * Writes the specified byte to this file. The write starts at
544 * the current file pointer.
545 *
546 * @param b the {@code byte} to be written.
547 * @throws IOException if an I/O error occurs.
548 */
549 public void write(int b) throws IOException {
550 long comp = Blocker.begin();
551 try {
552 write0(b);
553 } finally {
554 Blocker.end(comp);
555 }
556 }
557
558 private native void write0(int b) throws IOException;
559
560 /**
561 * Writes a sub array as a sequence of bytes.
562 *
563 * @param b the data to be written
564 * @param off the start offset in the data
565 * @param len the number of bytes that are written
566 * @throws IOException If an I/O error has occurred.
567 */
568 private void writeBytes(byte[] b, int off, int len) throws IOException {
569 long comp = Blocker.begin();
570 try {
571 writeBytes0(b, off, len);
572 } finally {
573 Blocker.end(comp);
574 }
575 }
576
577 private native void writeBytes0(byte[] b, int off, int len) throws IOException;
578
579 /**
580 * Writes {@code b.length} bytes from the specified byte array
581 * to this file, starting at the current file pointer.
582 *
583 * @param b the data.
584 * @throws IOException if an I/O error occurs.
585 */
586 public void write(byte[] b) throws IOException {
587 writeBytes(b, 0, b.length);
588 }
589
590 /**
591 * Writes {@code len} bytes from the specified byte array
592 * starting at offset {@code off} to this file.
593 *
594 * @param b the data.
595 * @param off the start offset in the data.
596 * @param len the number of bytes to write.
597 * @throws IOException if an I/O error occurs.
598 * @throws IndexOutOfBoundsException {@inheritDoc}
599 */
600 public void write(byte[] b, int off, int len) throws IOException {
601 writeBytes(b, off, len);
602 }
603
604 // 'Random access' stuff
605
606 /**
607 * Returns the current offset in this file.
608 *
609 * @return the offset from the beginning of the file, in bytes,
610 * at which the next read or write occurs.
611 * @throws IOException if an I/O error occurs.
612 */
613 public native long getFilePointer() throws IOException;
614
615 /**
616 * Sets the file-pointer offset, measured from the beginning of this
617 * file, at which the next read or write occurs. The offset may be
618 * set beyond the end of the file. Setting the offset beyond the end
619 * of the file does not change the file length. The file length will
620 * change only by writing after the offset has been set beyond the end
621 * of the file.
622 *
623 * @param pos the offset position, measured in bytes from the
624 * beginning of the file, at which to set the file
625 * pointer.
626 * @throws IOException if {@code pos} is less than
627 * {@code 0} or if an I/O error occurs.
628 */
629 public void seek(long pos) throws IOException {
630 if (pos < 0) {
631 throw new IOException("Negative seek offset");
632 }
633 long comp = Blocker.begin();
634 try {
635 seek0(pos);
636 } finally {
637 Blocker.end(comp);
638 }
639 }
640
641 private native void seek0(long pos) throws IOException;
642
643 /**
644 * Returns the length of this file.
645 *
646 * @return the length of this file, measured in bytes.
647 * @throws IOException if an I/O error occurs.
648 */
649 public long length() throws IOException {
650 long comp = Blocker.begin();
651 try {
652 return length0();
653 } finally {
654 Blocker.end(comp);
655 }
656 }
657
658 private native long length0() throws IOException;
659
660 /**
661 * Sets the length of this file.
662 *
663 * <p> If the present length of the file as returned by the
664 * {@linkplain #length length} method is greater than the desired length
665 * of the file specified by the {@code newLength} argument, then the file
666 * will be truncated.
667 *
668 * <p> If the present length of the file is smaller than the desired length,
669 * then the file will be extended. The contents of the extended portion of
670 * the file are not defined.
671 *
672 * <p> If the present length of the file is equal to the desired length,
673 * then the file and its length will be unchanged.
674 *
675 * <p> In all cases, after this method returns, the file offset as returned
676 * by the {@linkplain #getFilePointer getFilePointer} method will equal the
677 * minimum of the desired length and the file offset before this method was
678 * called, even if the length is unchanged. In other words, this method
679 * constrains the file offset to the closed interval {@code [0,newLength]}.
680 *
681 * @param newLength The desired length of the file
682 * @throws IOException If the argument is negative or
683 * if some other I/O error occurs
684 * @since 1.2
685 */
686 public void setLength(long newLength) throws IOException {
687 long comp = Blocker.begin();
688 try {
689 setLength0(newLength);
690 } finally {
691 Blocker.end(comp);
692 }
693 }
694
695 private native void setLength0(long newLength) throws IOException;
696
697 /**
698 * Closes this random access file stream and releases any system
699 * resources associated with the stream. A closed random access
700 * file cannot perform input or output operations and cannot be
701 * reopened.
702 *
703 * <p> If this file has an associated channel then the channel is closed
704 * as well.
705 *
706 * @apiNote
707 * If this stream has an associated channel then this method will close the
708 * channel, which in turn will close this stream. Subclasses that override
709 * this method should be prepared to handle possible reentrant invocation.
710 *
711 * @throws IOException if an I/O error occurs.
712 */
713 public void close() throws IOException {
714 if (closed) {
715 return;
716 }
717 synchronized (closeLock) {
718 if (closed) {
719 return;
720 }
721 closed = true;
722 }
723
724 FileChannel fc = channel;
725 if (fc != null) {
726 // possible race with getChannel(), benign since
727 // FileChannel.close is final and idempotent
728 fc.close();
729 }
730
731 fd.closeAll(new Closeable() {
732 public void close() throws IOException {
733 fd.close();
734 }
735 });
736 }
737
738 //
739 // Some "reading/writing Java data types" methods stolen from
740 // DataInputStream and DataOutputStream.
741 //
742
743 /**
744 * Reads a {@code boolean} from this file. This method reads a
745 * single byte from the file, starting at the current file pointer.
746 * A value of {@code 0} represents
747 * {@code false}. Any other value represents {@code true}.
748 * This method blocks until the byte is read, the end of the stream
749 * is detected, or an exception is thrown.
750 *
751 * @return the {@code boolean} value read.
752 * @throws EOFException if this file has reached the end.
753 * @throws IOException if an I/O error occurs.
754 */
755 public final boolean readBoolean() throws IOException {
756 return readUnsignedByte() != 0;
757 }
758
759 /**
760 * Reads a signed eight-bit value from this file. This method reads a
761 * byte from the file, starting from the current file pointer.
762 * If the byte read is {@code b}, where
763 * {@code 0 <= b <= 255},
764 * then the result is:
765 * {@snippet lang=java :
766 * (byte)(b)
767 * }
768 * <p>
769 * This method blocks until the byte is read, the end of the stream
770 * is detected, or an exception is thrown.
771 *
772 * @return the next byte of this file as a signed eight-bit
773 * {@code byte}.
774 * @throws EOFException if this file has reached the end.
775 * @throws IOException if an I/O error occurs.
776 */
777 public final byte readByte() throws IOException {
778 return (byte) readUnsignedByte();
779 }
780
781 /**
782 * Reads an unsigned eight-bit number from this file. This method reads
783 * a byte from this file, starting at the current file pointer,
784 * and returns that byte.
785 * <p>
786 * This method blocks until the byte is read, the end of the stream
787 * is detected, or an exception is thrown.
788 *
789 * @return the next byte of this file, interpreted as an unsigned
790 * eight-bit number.
791 * @throws EOFException if this file has reached the end.
792 * @throws IOException if an I/O error occurs.
793 */
794 public final int readUnsignedByte() throws IOException {
795 int ch = this.read();
796 if (ch < 0)
797 throw new EOFException();
798 return ch;
799 }
800
801 /**
802 * Reads a signed 16-bit number from this file. The method reads two
803 * bytes from this file, starting at the current file pointer.
804 * If the two bytes read, in order, are
805 * {@code b1} and {@code b2}, where each of the two values is
806 * between {@code 0} and {@code 255}, inclusive, then the
807 * result is equal to:
808 * {@snippet lang=java :
809 * (short)((b1 << 8) | b2)
810 * }
811 * <p>
812 * This method blocks until the two bytes are read, the end of the
813 * stream is detected, or an exception is thrown.
814 *
815 * @return the next two bytes of this file, interpreted as a signed
816 * 16-bit number.
817 * @throws EOFException if this file reaches the end before reading
818 * two bytes.
819 * @throws IOException if an I/O error occurs.
820 */
821 public final short readShort() throws IOException {
822 return (short) readUnsignedShort();
823 }
824
825 /**
826 * Reads an unsigned 16-bit number from this file. This method reads
827 * two bytes from the file, starting at the current file pointer.
828 * If the bytes read, in order, are
829 * {@code b1} and {@code b2}, where
830 * {@code 0 <= b1, b2 <= 255},
831 * then the result is equal to:
832 * {@snippet lang=java :
833 * (b1 << 8) | b2
834 * }
835 * <p>
836 * This method blocks until the two bytes are read, the end of the
837 * stream is detected, or an exception is thrown.
838 *
839 * @return the next two bytes of this file, interpreted as an unsigned
840 * 16-bit integer.
841 * @throws EOFException if this file reaches the end before reading
842 * two bytes.
843 * @throws IOException if an I/O error occurs.
844 */
845 public final int readUnsignedShort() throws IOException {
846 readFully(buffer, 0, Short.BYTES);
847 return ((buffer[1] & 0xff) ) +
848 ((buffer[0] & 0xff) << 8);
849 }
850
851 /**
852 * Reads a character from this file. This method reads two
853 * bytes from the file, starting at the current file pointer.
854 * If the bytes read, in order, are
855 * {@code b1} and {@code b2}, where
856 * {@code 0 <= b1, b2 <= 255},
857 * then the result is equal to:
858 * {@snippet lang=java :
859 * (char)((b1 << 8) | b2)
860 * }
861 * <p>
862 * This method blocks until the two bytes are read, the end of the
863 * stream is detected, or an exception is thrown.
864 *
865 * @return the next two bytes of this file, interpreted as a
866 * {@code char}.
867 * @throws EOFException if this file reaches the end before reading
868 * two bytes.
869 * @throws IOException if an I/O error occurs.
870 */
871 public final char readChar() throws IOException {
872 return (char) readUnsignedShort();
873 }
874
875 /**
876 * Reads a signed 32-bit integer from this file. This method reads 4
877 * bytes from the file, starting at the current file pointer.
878 * If the bytes read, in order, are {@code b1},
879 * {@code b2}, {@code b3}, and {@code b4}, where
880 * {@code 0 <= b1, b2, b3, b4 <= 255},
881 * then the result is equal to:
882 * {@snippet lang=java :
883 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
884 * }
885 * <p>
886 * This method blocks until the four bytes are read, the end of the
887 * stream is detected, or an exception is thrown.
888 *
889 * @return the next four bytes of this file, interpreted as an
890 * {@code int}.
891 * @throws EOFException if this file reaches the end before reading
892 * four bytes.
893 * @throws IOException if an I/O error occurs.
894 */
895 public final int readInt() throws IOException {
896 readFully(buffer, 0, Integer.BYTES);
897 return ByteArray.getInt(buffer, 0);
898 }
899
900 /**
901 * Reads a signed 64-bit integer from this file. This method reads eight
902 * bytes from the file, starting at the current file pointer.
903 * If the bytes read, in order, are
904 * {@code b1}, {@code b2}, {@code b3},
905 * {@code b4}, {@code b5}, {@code b6},
906 * {@code b7}, and {@code b8,} where:
907 * {@snippet :
908 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <= 255
909 * }
910 * <p>
911 * then the result is equal to:
912 * {@snippet lang=java :
913 * ((long)b1 << 56) + ((long)b2 << 48)
914 * + ((long)b3 << 40) + ((long)b4 << 32)
915 * + ((long)b5 << 24) + ((long)b6 << 16)
916 * + ((long)b7 << 8) + b8
917 * }
918 * <p>
919 * This method blocks until the eight bytes are read, the end of the
920 * stream is detected, or an exception is thrown.
921 *
922 * @return the next eight bytes of this file, interpreted as a
923 * {@code long}.
924 * @throws EOFException if this file reaches the end before reading
925 * eight bytes.
926 * @throws IOException if an I/O error occurs.
927 */
928 public final long readLong() throws IOException {
929 readFully(buffer, 0, Long.BYTES);
930 return ByteArray.getLong(buffer, 0);
931 }
932
933 /**
934 * Reads a {@code float} from this file. This method reads an
935 * {@code int} value, starting at the current file pointer,
936 * as if by the {@code readInt} method
937 * and then converts that {@code int} to a {@code float}
938 * using the {@code intBitsToFloat} method in class
939 * {@code Float}.
940 * <p>
941 * This method blocks until the four bytes are read, the end of the
942 * stream is detected, or an exception is thrown.
943 *
944 * @return the next four bytes of this file, interpreted as a
945 * {@code float}.
946 * @throws EOFException if this file reaches the end before reading
947 * four bytes.
948 * @throws IOException if an I/O error occurs.
949 * @see java.io.RandomAccessFile#readInt()
950 * @see java.lang.Float#intBitsToFloat(int)
951 */
952 public final float readFloat() throws IOException {
953 readFully(buffer, 0, Float.BYTES);
954 return ByteArray.getFloat(buffer, 0);
955 }
956
957 /**
958 * Reads a {@code double} from this file. This method reads a
959 * {@code long} value, starting at the current file pointer,
960 * as if by the {@code readLong} method
961 * and then converts that {@code long} to a {@code double}
962 * using the {@code longBitsToDouble} method in
963 * class {@code Double}.
964 * <p>
965 * This method blocks until the eight bytes are read, the end of the
966 * stream is detected, or an exception is thrown.
967 *
968 * @return the next eight bytes of this file, interpreted as a
969 * {@code double}.
970 * @throws EOFException if this file reaches the end before reading
971 * eight bytes.
972 * @throws IOException if an I/O error occurs.
973 * @see java.io.RandomAccessFile#readLong()
974 * @see java.lang.Double#longBitsToDouble(long)
975 */
976 public final double readDouble() throws IOException {
977 readFully(buffer, 0, Double.BYTES);
978 return ByteArray.getDouble(buffer, 0);
979 }
980
981 /**
982 * Reads the next line of text from this file. This method successively
983 * reads bytes from the file, starting at the current file pointer,
984 * until it reaches a line terminator or the end
985 * of the file. Each byte is converted into a character by taking the
986 * byte's value for the lower eight bits of the character and setting the
987 * high eight bits of the character to zero. This method does not,
988 * therefore, support the full Unicode character set.
989 *
990 * <p> A line of text is terminated by a carriage-return character
991 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a
992 * carriage-return character immediately followed by a newline character,
993 * or the end of the file. Line-terminating characters are discarded and
994 * are not included as part of the string returned.
995 *
996 * <p> This method blocks until a newline character is read, a carriage
997 * return and the byte following it are read (to see if it is a newline),
998 * the end of the file is reached, or an exception is thrown.
999 *
1000 * @return the next line of text from this file, or null if end
1001 * of file is encountered before even one byte is read.
1002 * @throws IOException if an I/O error occurs.
1003 */
1004
1005 public final String readLine() throws IOException {
1006 StringBuilder input = new StringBuilder();
1007 int c = -1;
1008 boolean eol = false;
1009
1010 while (!eol) {
1011 switch (c = read()) {
1012 case -1, '\n' -> eol = true;
1013 case '\r' -> {
1014 eol = true;
1015 long cur = getFilePointer();
1016 if ((read()) != '\n') {
1017 seek(cur);
1018 }
1019 }
1020 default -> input.append((char) c);
1021 }
1022 }
1023
1024 if ((c == -1) && (input.length() == 0)) {
1025 return null;
1026 }
1027 return input.toString();
1028 }
1029
1030 /**
1031 * Reads in a string from this file. The string has been encoded
1032 * using a
1033 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1034 * format.
1035 * <p>
1036 * The first two bytes are read, starting from the current file
1037 * pointer, as if by
1038 * {@code readUnsignedShort}. This value gives the number of
1039 * following bytes that are in the encoded string, not
1040 * the length of the resulting string. The following bytes are then
1041 * interpreted as bytes encoding characters in the modified UTF-8 format
1042 * and are converted into characters.
1043 * <p>
1044 * This method blocks until all the bytes are read, the end of the
1045 * stream is detected, or an exception is thrown.
1046 *
1047 * @return a Unicode string.
1048 * @throws EOFException if this file reaches the end before
1049 * reading all the bytes.
1050 * @throws IOException if an I/O error occurs.
1051 * @throws UTFDataFormatException if the bytes do not represent
1052 * valid modified UTF-8 encoding of a Unicode string.
1053 * @see java.io.RandomAccessFile#readUnsignedShort()
1054 */
1055 public final String readUTF() throws IOException {
1056 return DataInputStream.readUTF(this);
1057 }
1058
1059 /**
1060 * Writes a {@code boolean} to the file as a one-byte value. The
1061 * value {@code true} is written out as the value
1062 * {@code (byte)1}; the value {@code false} is written out
1063 * as the value {@code (byte)0}. The write starts at
1064 * the current position of the file pointer.
1065 *
1066 * @param v a {@code boolean} value to be written.
1067 * @throws IOException if an I/O error occurs.
1068 */
1069 public final void writeBoolean(boolean v) throws IOException {
1070 write(v ? 1 : 0);
1071 }
1072
1073 /**
1074 * Writes a {@code byte} to the file as a one-byte value. The
1075 * write starts at the current position of the file pointer.
1076 *
1077 * @param v a {@code byte} value to be written.
1078 * @throws IOException if an I/O error occurs.
1079 */
1080 public final void writeByte(int v) throws IOException {
1081 write(v);
1082 }
1083
1084 /**
1085 * Writes a {@code short} to the file as two bytes, high byte first.
1086 * The write starts at the current position of the file pointer.
1087 *
1088 * @param v a {@code short} to be written.
1089 * @throws IOException if an I/O error occurs.
1090 */
1091 public final void writeShort(int v) throws IOException {
1092 buffer[1] = (byte)(v );
1093 buffer[0] = (byte)(v >>> 8);
1094 write(buffer, 0, Short.BYTES);
1095 }
1096
1097 /**
1098 * Writes a {@code char} to the file as a two-byte value, high
1099 * byte first. The write starts at the current position of the
1100 * file pointer.
1101 *
1102 * @param v a {@code char} value to be written.
1103 * @throws IOException if an I/O error occurs.
1104 */
1105 public final void writeChar(int v) throws IOException {
1106 writeShort(v);
1107 }
1108
1109 /**
1110 * Writes an {@code int} to the file as four bytes, high byte first.
1111 * The write starts at the current position of the file pointer.
1112 *
1113 * @param v an {@code int} to be written.
1114 * @throws IOException if an I/O error occurs.
1115 */
1116 public final void writeInt(int v) throws IOException {
1117 ByteArray.setInt(buffer, 0, v);
1118 write(buffer, 0, Integer.BYTES);
1119 //written += 4;
1120 }
1121
1122 /**
1123 * Writes a {@code long} to the file as eight bytes, high byte first.
1124 * The write starts at the current position of the file pointer.
1125 *
1126 * @param v a {@code long} to be written.
1127 * @throws IOException if an I/O error occurs.
1128 */
1129 public final void writeLong(long v) throws IOException {
1130 ByteArray.setLong(buffer, 0, v);
1131 write(buffer, 0, Long.BYTES);
1132 }
1133
1134 /**
1135 * Converts the float argument to an {@code int} using the
1136 * {@code floatToIntBits} method in class {@code Float},
1137 * and then writes that {@code int} value to the file as a
1138 * four-byte quantity, high byte first. The write starts at the
1139 * current position of the file pointer.
1140 *
1141 * @param v a {@code float} value to be written.
1142 * @throws IOException if an I/O error occurs.
1143 * @see java.lang.Float#floatToIntBits(float)
1144 */
1145 public final void writeFloat(float v) throws IOException {
1146 ByteArray.setFloat(buffer, 0, v);
1147 write(buffer, 0, Float.BYTES);
1148 }
1149
1150 /**
1151 * Converts the double argument to a {@code long} using the
1152 * {@code doubleToLongBits} method in class {@code Double},
1153 * and then writes that {@code long} value to the file as an
1154 * eight-byte quantity, high byte first. The write starts at the current
1155 * position of the file pointer.
1156 *
1157 * @param v a {@code double} value to be written.
1158 * @throws IOException if an I/O error occurs.
1159 * @see java.lang.Double#doubleToLongBits(double)
1160 */
1161 public final void writeDouble(double v) throws IOException {
1162 ByteArray.setDouble(buffer, 0, v);
1163 write(buffer, 0, Double.BYTES);
1164 }
1165
1166 /**
1167 * Writes the string to the file as a sequence of bytes. Each
1168 * character in the string is written out, in sequence, by discarding
1169 * its high eight bits. The write starts at the current position of
1170 * the file pointer.
1171 *
1172 * @param s a string of bytes to be written.
1173 * @throws IOException if an I/O error occurs.
1174 */
1175 @SuppressWarnings("deprecation")
1176 public final void writeBytes(String s) throws IOException {
1177 int len = s.length();
1178 byte[] b = new byte[len];
1179 s.getBytes(0, len, b, 0);
1180 writeBytes(b, 0, len);
1181 }
1182
1183 /**
1184 * Writes a string to the file as a sequence of characters. Each
1185 * character is written to the data output stream as if by the
1186 * {@code writeChar} method. The write starts at the current
1187 * position of the file pointer.
1188 *
1189 * @param s a {@code String} value to be written.
1190 * @throws IOException if an I/O error occurs.
1191 * @see java.io.RandomAccessFile#writeChar(int)
1192 */
1193 public final void writeChars(String s) throws IOException {
1194 int clen = s.length();
1195 int blen = 2*clen;
1196 byte[] b = new byte[blen];
1197 char[] c = new char[clen];
1198 s.getChars(0, clen, c, 0);
1199 for (int i = 0, j = 0; i < clen; i++) {
1200 b[j++] = (byte)(c[i] >>> 8);
1201 b[j++] = (byte)(c[i] >>> 0);
1202 }
1203 writeBytes(b, 0, blen);
1204 }
1205
1206 /**
1207 * Writes a string to the file using
1208 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1209 * encoding in a machine-independent manner.
1210 * <p>
1211 * First, two bytes are written to the file, starting at the
1212 * current file pointer, as if by the
1213 * {@code writeShort} method giving the number of bytes to
1214 * follow. This value is the number of bytes actually written out,
1215 * not the length of the string. Following the length, each character
1216 * of the string is output, in sequence, using the modified UTF-8 encoding
1217 * for each character.
1218 *
1219 * @param str a string to be written.
1220 * @throws IOException if an I/O error occurs.
1221 */
1222 public final void writeUTF(String str) throws IOException {
1223 DataOutputStream.writeUTF(str, this);
1224 }
1225
1226 private static native void initIDs();
1227
1228 static {
1229 initIDs();
1230 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess()
1231 {
1232 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag
1233 // is only implemented/supported on Windows.
1234 public RandomAccessFile openAndDelete(File file, String mode)
1235 throws IOException
1236 {
1237 return new RandomAccessFile(file, mode, true);
1238 }
1239 });
1240 }
1241 }