1 /*
2 * Copyright (c) 2000, 2013, 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 sun.nio.ch;
27
28 import java.io.FileDescriptor;
29 import java.io.IOException;
30 import java.nio.ByteBuffer;
31 import java.nio.MappedByteBuffer;
32 import java.nio.channels.ClosedByInterruptException;
33 import java.nio.channels.ClosedChannelException;
34 import java.nio.channels.FileChannel;
35 import java.nio.channels.FileLock;
36 import java.nio.channels.FileLockInterruptionException;
37 import java.nio.channels.NonReadableChannelException;
38 import java.nio.channels.NonWritableChannelException;
39 import java.nio.channels.OverlappingFileLockException;
40 import java.nio.channels.ReadableByteChannel;
41 import java.nio.channels.WritableByteChannel;
42 import java.security.AccessController;
43 import java.util.ArrayList;
44 import java.util.List;
45
46 import sun.misc.Cleaner;
47 import sun.security.action.GetPropertyAction;
48
49 public class FileChannelImpl
50 extends FileChannel
51 {
52 // Memory allocation size for mapping buffers
53 private static final long allocationGranularity;
54
55 // Used to make native read and write calls
56 private final FileDispatcher nd;
57
58 // File descriptor
59 private final FileDescriptor fd;
60
61 // File access mode (immutable)
62 private final boolean writable;
63 private final boolean readable;
64 private final boolean append;
65
66 // Required to prevent finalization of creating stream (immutable)
67 private final Object parent;
68
69 // The path of the referenced file
70 // (null if the parent stream is created with a file descriptor)
71 private final String path;
72
73 // Thread-safe set of IDs of native threads, for signalling
74 private final NativeThreadSet threads = new NativeThreadSet(2);
75
76 // Lock for operations involving position and size
77 private final Object positionLock = new Object();
78
79 private FileChannelImpl(FileDescriptor fd, String path, boolean readable,
80 boolean writable, boolean append, Object parent)
81 {
82 this.fd = fd;
83 this.readable = readable;
84 this.writable = writable;
85 this.append = append;
86 this.parent = parent;
87 this.path = path;
88 this.nd = new FileDispatcherImpl(append);
89 }
90
91 // Used by FileInputStream.getChannel() and RandomAccessFile.getChannel()
92 public static FileChannel open(FileDescriptor fd, String path,
93 boolean readable, boolean writable,
94 Object parent)
95 {
96 return new FileChannelImpl(fd, path, readable, writable, false, parent);
97 }
98
99 // Used by FileOutputStream.getChannel
100 public static FileChannel open(FileDescriptor fd, String path,
101 boolean readable, boolean writable,
102 boolean append, Object parent)
103 {
104 return new FileChannelImpl(fd, path, readable, writable, append, parent);
105 }
106
107 private void ensureOpen() throws IOException {
108 if (!isOpen())
109 throw new ClosedChannelException();
110 }
111
112
113 // -- Standard channel operations --
114
115 protected void implCloseChannel() throws IOException {
116 // Release and invalidate any locks that we still hold
117 if (fileLockTable != null) {
118 for (FileLock fl: fileLockTable.removeAll()) {
119 synchronized (fl) {
120 if (fl.isValid()) {
121 nd.release(fd, fl.position(), fl.size());
122 ((FileLockImpl)fl).invalidate();
123 }
124 }
125 }
126 }
127
128 // signal any threads blocked on this channel
129 threads.signalAndWait();
130
131 if (parent != null) {
132
133 // Close the fd via the parent stream's close method. The parent
134 // will reinvoke our close method, which is defined in the
135 // superclass AbstractInterruptibleChannel, but the isOpen logic in
136 // that method will prevent this method from being reinvoked.
137 //
138 ((java.io.Closeable)parent).close();
139 } else {
140 nd.close(fd);
141 }
142
143 }
144
145 public int read(ByteBuffer dst) throws IOException {
146 ensureOpen();
147 if (!readable)
148 throw new NonReadableChannelException();
149 synchronized (positionLock) {
150 int n = 0;
151 int ti = -1;
152 try {
153 begin();
154 ti = threads.add();
155 if (!isOpen())
156 return 0;
157 do {
158 n = IOUtil.read(fd, dst, -1, nd);
159 } while ((n == IOStatus.INTERRUPTED) && isOpen());
160 return IOStatus.normalize(n);
161 } finally {
162 threads.remove(ti);
163 end(n > 0);
164 assert IOStatus.check(n);
165 }
166 }
167 }
168
169 public long read(ByteBuffer[] dsts, int offset, int length)
170 throws IOException
171 {
172 if ((offset < 0) || (length < 0) || (offset > dsts.length - length))
173 throw new IndexOutOfBoundsException();
174 ensureOpen();
175 if (!readable)
176 throw new NonReadableChannelException();
177 synchronized (positionLock) {
178 long n = 0;
179 int ti = -1;
180 try {
181 begin();
182 ti = threads.add();
183 if (!isOpen())
184 return 0;
185 do {
186 n = IOUtil.read(fd, dsts, offset, length, nd);
187 } while ((n == IOStatus.INTERRUPTED) && isOpen());
188 return IOStatus.normalize(n);
189 } finally {
190 threads.remove(ti);
191 end(n > 0);
192 assert IOStatus.check(n);
193 }
194 }
195 }
196
197 public int write(ByteBuffer src) throws IOException {
198 ensureOpen();
199 if (!writable)
200 throw new NonWritableChannelException();
201 synchronized (positionLock) {
202 int n = 0;
203 int ti = -1;
204 try {
205 begin();
206 ti = threads.add();
207 if (!isOpen())
208 return 0;
209 do {
210 n = IOUtil.write(fd, src, -1, nd);
211 } while ((n == IOStatus.INTERRUPTED) && isOpen());
212 return IOStatus.normalize(n);
213 } finally {
214 threads.remove(ti);
215 end(n > 0);
216 assert IOStatus.check(n);
217 }
218 }
219 }
220
221 public long write(ByteBuffer[] srcs, int offset, int length)
222 throws IOException
223 {
224 if ((offset < 0) || (length < 0) || (offset > srcs.length - length))
225 throw new IndexOutOfBoundsException();
226 ensureOpen();
227 if (!writable)
228 throw new NonWritableChannelException();
229 synchronized (positionLock) {
230 long n = 0;
231 int ti = -1;
232 try {
233 begin();
234 ti = threads.add();
235 if (!isOpen())
236 return 0;
237 do {
238 n = IOUtil.write(fd, srcs, offset, length, nd);
239 } while ((n == IOStatus.INTERRUPTED) && isOpen());
240 return IOStatus.normalize(n);
241 } finally {
242 threads.remove(ti);
243 end(n > 0);
244 assert IOStatus.check(n);
245 }
246 }
247 }
248
249 // -- Other operations --
250
251 public long position() throws IOException {
252 ensureOpen();
253 synchronized (positionLock) {
254 long p = -1;
255 int ti = -1;
256 try {
257 begin();
258 ti = threads.add();
259 if (!isOpen())
260 return 0;
261 do {
262 // in append-mode then position is advanced to end before writing
263 p = (append) ? nd.size(fd) : position0(fd, -1);
264 } while ((p == IOStatus.INTERRUPTED) && isOpen());
265 return IOStatus.normalize(p);
266 } finally {
267 threads.remove(ti);
268 end(p > -1);
269 assert IOStatus.check(p);
270 }
271 }
272 }
273
274 public FileChannel position(long newPosition) throws IOException {
275 ensureOpen();
276 if (newPosition < 0)
277 throw new IllegalArgumentException();
278 synchronized (positionLock) {
279 long p = -1;
280 int ti = -1;
281 try {
282 begin();
283 ti = threads.add();
284 if (!isOpen())
285 return null;
286 do {
287 p = position0(fd, newPosition);
288 } while ((p == IOStatus.INTERRUPTED) && isOpen());
289 return this;
290 } finally {
291 threads.remove(ti);
292 end(p > -1);
293 assert IOStatus.check(p);
294 }
295 }
296 }
297
298 public long size() throws IOException {
299 ensureOpen();
300 synchronized (positionLock) {
301 long s = -1;
302 int ti = -1;
303 try {
304 begin();
305 ti = threads.add();
306 if (!isOpen())
307 return -1;
308 do {
309 s = nd.size(fd);
310 } while ((s == IOStatus.INTERRUPTED) && isOpen());
311 return IOStatus.normalize(s);
312 } finally {
313 threads.remove(ti);
314 end(s > -1);
315 assert IOStatus.check(s);
316 }
317 }
318 }
319
320 public FileChannel truncate(long newSize) throws IOException {
321 ensureOpen();
322 if (newSize < 0)
323 throw new IllegalArgumentException("Negative size");
324 if (!writable)
325 throw new NonWritableChannelException();
326 synchronized (positionLock) {
327 int rv = -1;
328 long p = -1;
329 int ti = -1;
330 try {
331 begin();
332 ti = threads.add();
333 if (!isOpen())
334 return null;
335
336 // get current size
337 long size;
338 do {
339 size = nd.size(fd);
340 } while ((size == IOStatus.INTERRUPTED) && isOpen());
341 if (!isOpen())
342 return null;
343
344 // get current position
345 do {
346 p = position0(fd, -1);
347 } while ((p == IOStatus.INTERRUPTED) && isOpen());
348 if (!isOpen())
349 return null;
350 assert p >= 0;
351
352 // truncate file if given size is less than the current size
353 if (newSize < size) {
354 do {
355 rv = nd.truncate(fd, newSize);
356 } while ((rv == IOStatus.INTERRUPTED) && isOpen());
357 if (!isOpen())
358 return null;
359 }
360
361 // if position is beyond new size then adjust it
362 if (p > newSize)
363 p = newSize;
364 do {
365 rv = (int)position0(fd, p);
366 } while ((rv == IOStatus.INTERRUPTED) && isOpen());
367 return this;
368 } finally {
369 threads.remove(ti);
370 end(rv > -1);
371 assert IOStatus.check(rv);
372 }
373 }
374 }
375
376 public void force(boolean metaData) throws IOException {
377 ensureOpen();
378 int rv = -1;
379 int ti = -1;
380 try {
381 begin();
382 ti = threads.add();
383 if (!isOpen())
384 return;
385 do {
386 rv = nd.force(fd, metaData);
387 } while ((rv == IOStatus.INTERRUPTED) && isOpen());
388 } finally {
389 threads.remove(ti);
390 end(rv > -1);
391 assert IOStatus.check(rv);
392 }
393 }
394
395 // Assume at first that the underlying kernel supports sendfile();
396 // set this to false if we find out later that it doesn't
397 //
398 private static volatile boolean transferSupported = true;
399
400 // Assume that the underlying kernel sendfile() will work if the target
401 // fd is a pipe; set this to false if we find out later that it doesn't
402 //
403 private static volatile boolean pipeSupported = true;
404
405 // Assume that the underlying kernel sendfile() will work if the target
406 // fd is a file; set this to false if we find out later that it doesn't
407 //
408 private static volatile boolean fileSupported = true;
409
410 private long transferToDirectly(long position, int icount,
411 WritableByteChannel target)
412 throws IOException
413 {
414 if (!transferSupported)
415 return IOStatus.UNSUPPORTED;
416
417 FileDescriptor targetFD = null;
418 if (target instanceof FileChannelImpl) {
419 if (!fileSupported)
420 return IOStatus.UNSUPPORTED_CASE;
421 targetFD = ((FileChannelImpl)target).fd;
422 } else if (target instanceof SelChImpl) {
423 // Direct transfer to pipe causes EINVAL on some configurations
424 if ((target instanceof SinkChannelImpl) && !pipeSupported)
425 return IOStatus.UNSUPPORTED_CASE;
426 targetFD = ((SelChImpl)target).getFD();
427 }
428 if (targetFD == null)
429 return IOStatus.UNSUPPORTED;
430 int thisFDVal = IOUtil.fdVal(fd);
431 int targetFDVal = IOUtil.fdVal(targetFD);
432 if (thisFDVal == targetFDVal) // Not supported on some configurations
433 return IOStatus.UNSUPPORTED;
434
435 long n = -1;
436 int ti = -1;
437 try {
438 begin();
439 ti = threads.add();
440 if (!isOpen())
441 return -1;
442 do {
443 n = transferTo0(thisFDVal, position, icount, targetFDVal);
444 } while ((n == IOStatus.INTERRUPTED) && isOpen());
445 if (n == IOStatus.UNSUPPORTED_CASE) {
446 if (target instanceof SinkChannelImpl)
447 pipeSupported = false;
448 if (target instanceof FileChannelImpl)
449 fileSupported = false;
450 return IOStatus.UNSUPPORTED_CASE;
451 }
452 if (n == IOStatus.UNSUPPORTED) {
453 // Don't bother trying again
454 transferSupported = false;
455 return IOStatus.UNSUPPORTED;
456 }
457 return IOStatus.normalize(n);
458 } finally {
459 threads.remove(ti);
460 end (n > -1);
461 }
462 }
463
464 // Maximum size to map when using a mapped buffer
465 private static final long MAPPED_TRANSFER_SIZE = 8L*1024L*1024L;
466
467 private long transferToTrustedChannel(long position, long count,
468 WritableByteChannel target)
469 throws IOException
470 {
471 boolean isSelChImpl = (target instanceof SelChImpl);
472 if (!((target instanceof FileChannelImpl) || isSelChImpl))
473 return IOStatus.UNSUPPORTED;
474
475 // Trusted target: Use a mapped buffer
476 long remaining = count;
477 while (remaining > 0L) {
478 long size = Math.min(remaining, MAPPED_TRANSFER_SIZE);
479 try {
480 MappedByteBuffer dbb = map(MapMode.READ_ONLY, position, size);
481 try {
482 // ## Bug: Closing this channel will not terminate the write
483 int n = target.write(dbb);
484 assert n >= 0;
485 remaining -= n;
486 if (isSelChImpl) {
487 // one attempt to write to selectable channel
488 break;
489 }
490 assert n > 0;
491 position += n;
492 } finally {
493 unmap(dbb);
494 }
495 } catch (ClosedByInterruptException e) {
496 // target closed by interrupt as ClosedByInterruptException needs
497 // to be thrown after closing this channel.
498 assert !target.isOpen();
499 try {
500 close();
501 } catch (Throwable suppressed) {
502 e.addSuppressed(suppressed);
503 }
504 throw e;
505 } catch (IOException ioe) {
506 // Only throw exception if no bytes have been written
507 if (remaining == count)
508 throw ioe;
509 break;
510 }
511 }
512 return count - remaining;
513 }
514
515 private long transferToArbitraryChannel(long position, int icount,
516 WritableByteChannel target)
517 throws IOException
518 {
519 // Untrusted target: Use a newly-erased buffer
520 int c = Math.min(icount, TRANSFER_SIZE);
521 ByteBuffer bb = Util.getTemporaryDirectBuffer(c);
522 long tw = 0; // Total bytes written
523 long pos = position;
524 try {
525 Util.erase(bb);
526 while (tw < icount) {
527 bb.limit(Math.min((int)(icount - tw), TRANSFER_SIZE));
528 int nr = read(bb, pos);
529 if (nr <= 0)
530 break;
531 bb.flip();
532 // ## Bug: Will block writing target if this channel
533 // ## is asynchronously closed
534 int nw = target.write(bb);
535 tw += nw;
536 if (nw != nr)
537 break;
538 pos += nw;
539 bb.clear();
540 }
541 return tw;
542 } catch (IOException x) {
543 if (tw > 0)
544 return tw;
545 throw x;
546 } finally {
547 Util.releaseTemporaryDirectBuffer(bb);
548 }
549 }
550
551 public long transferTo(long position, long count,
552 WritableByteChannel target)
553 throws IOException
554 {
555 ensureOpen();
556 if (!target.isOpen())
557 throw new ClosedChannelException();
558 if (!readable)
559 throw new NonReadableChannelException();
560 if (target instanceof FileChannelImpl &&
561 !((FileChannelImpl)target).writable)
562 throw new NonWritableChannelException();
563 if ((position < 0) || (count < 0))
564 throw new IllegalArgumentException();
565 long sz = size();
566 if (position > sz)
567 return 0;
568 int icount = (int)Math.min(count, Integer.MAX_VALUE);
569 if ((sz - position) < icount)
570 icount = (int)(sz - position);
571
572 long n;
573
574 // Attempt a direct transfer, if the kernel supports it
575 if ((n = transferToDirectly(position, icount, target)) >= 0)
576 return n;
577
578 // Attempt a mapped transfer, but only to trusted channel types
579 if ((n = transferToTrustedChannel(position, icount, target)) >= 0)
580 return n;
581
582 // Slow path for untrusted targets
583 return transferToArbitraryChannel(position, icount, target);
584 }
585
586 private long transferFromFileChannel(FileChannelImpl src,
587 long position, long count)
588 throws IOException
589 {
590 if (!src.readable)
591 throw new NonReadableChannelException();
592 synchronized (src.positionLock) {
593 long pos = src.position();
594 long max = Math.min(count, src.size() - pos);
595
596 long remaining = max;
597 long p = pos;
598 while (remaining > 0L) {
599 long size = Math.min(remaining, MAPPED_TRANSFER_SIZE);
600 // ## Bug: Closing this channel will not terminate the write
601 MappedByteBuffer bb = src.map(MapMode.READ_ONLY, p, size);
602 try {
603 long n = write(bb, position);
604 assert n > 0;
605 p += n;
606 position += n;
607 remaining -= n;
608 } catch (IOException ioe) {
609 // Only throw exception if no bytes have been written
610 if (remaining == max)
611 throw ioe;
612 break;
613 } finally {
614 unmap(bb);
615 }
616 }
617 long nwritten = max - remaining;
618 src.position(pos + nwritten);
619 return nwritten;
620 }
621 }
622
623 private static final int TRANSFER_SIZE = 8192;
624
625 private long transferFromArbitraryChannel(ReadableByteChannel src,
626 long position, long count)
627 throws IOException
628 {
629 // Untrusted target: Use a newly-erased buffer
630 int c = (int)Math.min(count, TRANSFER_SIZE);
631 ByteBuffer bb = Util.getTemporaryDirectBuffer(c);
632 long tw = 0; // Total bytes written
633 long pos = position;
634 try {
635 Util.erase(bb);
636 while (tw < count) {
637 bb.limit((int)Math.min((count - tw), (long)TRANSFER_SIZE));
638 // ## Bug: Will block reading src if this channel
639 // ## is asynchronously closed
640 int nr = src.read(bb);
641 if (nr <= 0)
642 break;
643 bb.flip();
644 int nw = write(bb, pos);
645 tw += nw;
646 if (nw != nr)
647 break;
648 pos += nw;
649 bb.clear();
650 }
651 return tw;
652 } catch (IOException x) {
653 if (tw > 0)
654 return tw;
655 throw x;
656 } finally {
657 Util.releaseTemporaryDirectBuffer(bb);
658 }
659 }
660
661 public long transferFrom(ReadableByteChannel src,
662 long position, long count)
663 throws IOException
664 {
665 ensureOpen();
666 if (!src.isOpen())
667 throw new ClosedChannelException();
668 if (!writable)
669 throw new NonWritableChannelException();
670 if ((position < 0) || (count < 0))
671 throw new IllegalArgumentException();
672 if (position > size())
673 return 0;
674 if (src instanceof FileChannelImpl)
675 return transferFromFileChannel((FileChannelImpl)src,
676 position, count);
677
678 return transferFromArbitraryChannel(src, position, count);
679 }
680
681 public int read(ByteBuffer dst, long position) throws IOException {
682 if (dst == null)
683 throw new NullPointerException();
684 if (position < 0)
685 throw new IllegalArgumentException("Negative position");
686 if (!readable)
687 throw new NonReadableChannelException();
688 ensureOpen();
689 if (nd.needsPositionLock()) {
690 synchronized (positionLock) {
691 return readInternal(dst, position);
692 }
693 } else {
694 return readInternal(dst, position);
695 }
696 }
697
698 private int readInternal(ByteBuffer dst, long position) throws IOException {
699 assert !nd.needsPositionLock() || Thread.holdsLock(positionLock);
700 int n = 0;
701 int ti = -1;
702 try {
703 begin();
704 ti = threads.add();
705 if (!isOpen())
706 return -1;
707 do {
708 n = IOUtil.read(fd, dst, position, nd);
709 } while ((n == IOStatus.INTERRUPTED) && isOpen());
710 return IOStatus.normalize(n);
711 } finally {
712 threads.remove(ti);
713 end(n > 0);
714 assert IOStatus.check(n);
715 }
716 }
717
718 public int write(ByteBuffer src, long position) throws IOException {
719 if (src == null)
720 throw new NullPointerException();
721 if (position < 0)
722 throw new IllegalArgumentException("Negative position");
723 if (!writable)
724 throw new NonWritableChannelException();
725 ensureOpen();
726 if (nd.needsPositionLock()) {
727 synchronized (positionLock) {
728 return writeInternal(src, position);
729 }
730 } else {
731 return writeInternal(src, position);
732 }
733 }
734
735 private int writeInternal(ByteBuffer src, long position) throws IOException {
736 assert !nd.needsPositionLock() || Thread.holdsLock(positionLock);
737 int n = 0;
738 int ti = -1;
739 try {
740 begin();
741 ti = threads.add();
742 if (!isOpen())
743 return -1;
744 do {
745 n = IOUtil.write(fd, src, position, nd);
746 } while ((n == IOStatus.INTERRUPTED) && isOpen());
747 return IOStatus.normalize(n);
748 } finally {
749 threads.remove(ti);
750 end(n > 0);
751 assert IOStatus.check(n);
752 }
753 }
754
755
756 // -- Memory-mapped buffers --
757
758 private static class Unmapper
759 implements Runnable
760 {
761 // may be required to close file
762 private static final NativeDispatcher nd = new FileDispatcherImpl();
763
764 // keep track of mapped buffer usage
765 static volatile int count;
766 static volatile long totalSize;
767 static volatile long totalCapacity;
768
769 private volatile long address;
770 private final long size;
771 private final int cap;
772 private final FileDescriptor fd;
773
774 private Unmapper(long address, long size, int cap,
775 FileDescriptor fd)
776 {
777 assert (address != 0);
778 this.address = address;
779 this.size = size;
780 this.cap = cap;
781 this.fd = fd;
782
783 synchronized (Unmapper.class) {
784 count++;
785 totalSize += size;
786 totalCapacity += cap;
787 }
788 }
789
790 public void run() {
791 if (address == 0)
792 return;
793 unmap0(address, size);
794 address = 0;
795
796 // if this mapping has a valid file descriptor then we close it
797 if (fd.valid()) {
798 try {
799 nd.close(fd);
800 } catch (IOException ignore) {
801 // nothing we can do
802 }
803 }
804
805 synchronized (Unmapper.class) {
806 count--;
807 totalSize -= size;
808 totalCapacity -= cap;
809 }
810 }
811 }
812
813 private static void unmap(MappedByteBuffer bb) {
814 Cleaner cl = ((DirectBuffer)bb).cleaner();
815 if (cl != null)
816 cl.clean();
817 }
818
819 private static final int MAP_RO = 0;
820 private static final int MAP_RW = 1;
821 private static final int MAP_PV = 2;
822
823 public MappedByteBuffer map(MapMode mode, long position, long size)
824 throws IOException
825 {
826 ensureOpen();
827 if (mode == null)
828 throw new NullPointerException("Mode is null");
829 if (position < 0L)
830 throw new IllegalArgumentException("Negative position");
831 if (size < 0L)
832 throw new IllegalArgumentException("Negative size");
833 if (position + size < 0)
834 throw new IllegalArgumentException("Position + size overflow");
835 if (size > Integer.MAX_VALUE)
836 throw new IllegalArgumentException("Size exceeds Integer.MAX_VALUE");
837
838 int imode = -1;
839 if (mode == MapMode.READ_ONLY)
840 imode = MAP_RO;
841 else if (mode == MapMode.READ_WRITE)
842 imode = MAP_RW;
843 else if (mode == MapMode.PRIVATE)
844 imode = MAP_PV;
845 assert (imode >= 0);
846 if ((mode != MapMode.READ_ONLY) && !writable)
847 throw new NonWritableChannelException();
848 if (!readable)
849 throw new NonReadableChannelException();
850
851 long addr = -1;
852 int ti = -1;
853 try {
854 begin();
855 ti = threads.add();
856 if (!isOpen())
857 return null;
858
859 long filesize;
860 do {
861 filesize = nd.size(fd);
862 } while ((filesize == IOStatus.INTERRUPTED) && isOpen());
863 if (!isOpen())
864 return null;
865
866 if (filesize < position + size) { // Extend file size
867 if (!writable) {
868 throw new IOException("Channel not open for writing " +
869 "- cannot extend file to required size");
870 }
871 int rv;
872 do {
873 rv = nd.truncate(fd, position + size);
874 } while ((rv == IOStatus.INTERRUPTED) && isOpen());
875 if (!isOpen())
876 return null;
877 }
878 if (size == 0) {
879 addr = 0;
880 // a valid file descriptor is not required
881 FileDescriptor dummy = new FileDescriptor();
882 if ((!writable) || (imode == MAP_RO))
883 return Util.newMappedByteBufferR(0, 0, dummy, null);
884 else
885 return Util.newMappedByteBuffer(0, 0, dummy, null);
886 }
887
888 int pagePosition = (int)(position % allocationGranularity);
889 long mapPosition = position - pagePosition;
890 long mapSize = size + pagePosition;
891 try {
892 // If no exception was thrown from map0, the address is valid
893 addr = map0(imode, mapPosition, mapSize);
894 } catch (OutOfMemoryError x) {
895 // An OutOfMemoryError may indicate that we've exhausted memory
896 // so force gc and re-attempt map
897 System.gc();
898 try {
899 Thread.sleep(100);
900 } catch (InterruptedException y) {
901 Thread.currentThread().interrupt();
902 }
903 try {
904 addr = map0(imode, mapPosition, mapSize);
905 } catch (OutOfMemoryError y) {
906 // After a second OOME, fail
907 throw new IOException("Map failed", y);
908 }
909 }
910
911 // On Windows, and potentially other platforms, we need an open
912 // file descriptor for some mapping operations.
913 FileDescriptor mfd;
914 try {
915 mfd = nd.duplicateForMapping(fd);
916 } catch (IOException ioe) {
917 unmap0(addr, mapSize);
918 throw ioe;
919 }
920
921 assert (IOStatus.checkAll(addr));
922 assert (addr % allocationGranularity == 0);
923 int isize = (int)size;
924 Unmapper um = new Unmapper(addr, mapSize, isize, mfd);
925 if ((!writable) || (imode == MAP_RO)) {
926 return Util.newMappedByteBufferR(isize,
927 addr + pagePosition,
928 mfd,
929 um);
930 } else {
931 return Util.newMappedByteBuffer(isize,
932 addr + pagePosition,
933 mfd,
934 um);
935 }
936 } finally {
937 threads.remove(ti);
938 end(IOStatus.checkAll(addr));
939 }
940 }
941
942 /**
943 * Invoked by sun.management.ManagementFactoryHelper to create the management
944 * interface for mapped buffers.
945 */
946 public static sun.misc.JavaNioAccess.BufferPool getMappedBufferPool() {
947 return new sun.misc.JavaNioAccess.BufferPool() {
948 @Override
949 public String getName() {
950 return "mapped";
951 }
952 @Override
953 public long getCount() {
954 return Unmapper.count;
955 }
956 @Override
957 public long getTotalCapacity() {
958 return Unmapper.totalCapacity;
959 }
960 @Override
961 public long getMemoryUsed() {
962 return Unmapper.totalSize;
963 }
964 };
965 }
966
967 // -- Locks --
968
969
970
971 // keeps track of locks on this file
972 private volatile FileLockTable fileLockTable;
973
974 // indicates if file locks are maintained system-wide (as per spec)
975 private static boolean isSharedFileLockTable;
976
977 // indicates if the disableSystemWideOverlappingFileLockCheck property
978 // has been checked
979 private static volatile boolean propertyChecked;
980
981 // The lock list in J2SE 1.4/5.0 was local to each FileChannel instance so
982 // the overlap check wasn't system wide when there were multiple channels to
983 // the same file. This property is used to get 1.4/5.0 behavior if desired.
984 private static boolean isSharedFileLockTable() {
985 if (!propertyChecked) {
986 synchronized (FileChannelImpl.class) {
987 if (!propertyChecked) {
988 String value = AccessController.doPrivileged(
989 new GetPropertyAction(
990 "sun.nio.ch.disableSystemWideOverlappingFileLockCheck"));
991 isSharedFileLockTable = ((value == null) || value.equals("false"));
992 propertyChecked = true;
993 }
994 }
995 }
996 return isSharedFileLockTable;
997 }
998
999 private FileLockTable fileLockTable() throws IOException {
1000 if (fileLockTable == null) {
1001 synchronized (this) {
1002 if (fileLockTable == null) {
1003 if (isSharedFileLockTable()) {
1004 int ti = threads.add();
1005 try {
1006 ensureOpen();
1007 fileLockTable = FileLockTable.newSharedFileLockTable(this, fd);
1008 } finally {
1009 threads.remove(ti);
1010 }
1011 } else {
1012 fileLockTable = new SimpleFileLockTable();
1013 }
1014 }
1015 }
1016 }
1017 return fileLockTable;
1018 }
1019
1020 public FileLock lock(long position, long size, boolean shared)
1021 throws IOException
1022 {
1023 ensureOpen();
1024 if (shared && !readable)
1025 throw new NonReadableChannelException();
1026 if (!shared && !writable)
1027 throw new NonWritableChannelException();
1028 FileLockImpl fli = new FileLockImpl(this, position, size, shared);
1029 FileLockTable flt = fileLockTable();
1030 flt.add(fli);
1031 boolean completed = false;
1032 int ti = -1;
1033 try {
1034 begin();
1035 ti = threads.add();
1036 if (!isOpen())
1037 return null;
1038 int n;
1039 do {
1040 n = nd.lock(fd, true, position, size, shared);
1041 } while ((n == FileDispatcher.INTERRUPTED) && isOpen());
1042 if (isOpen()) {
1043 if (n == FileDispatcher.RET_EX_LOCK) {
1044 assert shared;
1045 FileLockImpl fli2 = new FileLockImpl(this, position, size,
1046 false);
1047 flt.replace(fli, fli2);
1048 fli = fli2;
1049 }
1050 completed = true;
1051 }
1052 } finally {
1053 if (!completed)
1054 flt.remove(fli);
1055 threads.remove(ti);
1056 try {
1057 end(completed);
1058 } catch (ClosedByInterruptException e) {
1059 throw new FileLockInterruptionException();
1060 }
1061 }
1062 return fli;
1063 }
1064
1065 public FileLock tryLock(long position, long size, boolean shared)
1066 throws IOException
1067 {
1068 ensureOpen();
1069 if (shared && !readable)
1070 throw new NonReadableChannelException();
1071 if (!shared && !writable)
1072 throw new NonWritableChannelException();
1073 FileLockImpl fli = new FileLockImpl(this, position, size, shared);
1074 FileLockTable flt = fileLockTable();
1075 flt.add(fli);
1076 int result;
1077
1078 int ti = threads.add();
1079 try {
1080 try {
1081 ensureOpen();
1082 result = nd.lock(fd, false, position, size, shared);
1083 } catch (IOException e) {
1084 flt.remove(fli);
1085 throw e;
1086 }
1087 if (result == FileDispatcher.NO_LOCK) {
1088 flt.remove(fli);
1089 return null;
1090 }
1091 if (result == FileDispatcher.RET_EX_LOCK) {
1092 assert shared;
1093 FileLockImpl fli2 = new FileLockImpl(this, position, size,
1094 false);
1095 flt.replace(fli, fli2);
1096 return fli2;
1097 }
1098 return fli;
1099 } finally {
1100 threads.remove(ti);
1101 }
1102 }
1103
1104 void release(FileLockImpl fli) throws IOException {
1105 int ti = threads.add();
1106 try {
1107 ensureOpen();
1108 nd.release(fd, fli.position(), fli.size());
1109 } finally {
1110 threads.remove(ti);
1111 }
1112 assert fileLockTable != null;
1113 fileLockTable.remove(fli);
1114 }
1115
1116 // -- File lock support --
1117
1118 /**
1119 * A simple file lock table that maintains a list of FileLocks obtained by a
1120 * FileChannel. Use to get 1.4/5.0 behaviour.
1121 */
1122 private static class SimpleFileLockTable extends FileLockTable {
1123 // synchronize on list for access
1124 private final List<FileLock> lockList = new ArrayList<FileLock>(2);
1125
1126 public SimpleFileLockTable() {
1127 }
1128
1129 private void checkList(long position, long size)
1130 throws OverlappingFileLockException
1131 {
1132 assert Thread.holdsLock(lockList);
1133 for (FileLock fl: lockList) {
1134 if (fl.overlaps(position, size)) {
1135 throw new OverlappingFileLockException();
1136 }
1137 }
1138 }
1139
1140 public void add(FileLock fl) throws OverlappingFileLockException {
1141 synchronized (lockList) {
1142 checkList(fl.position(), fl.size());
1143 lockList.add(fl);
1144 }
1145 }
1146
1147 public void remove(FileLock fl) {
1148 synchronized (lockList) {
1149 lockList.remove(fl);
1150 }
1151 }
1152
1153 public List<FileLock> removeAll() {
1154 synchronized(lockList) {
1155 List<FileLock> result = new ArrayList<FileLock>(lockList);
1156 lockList.clear();
1157 return result;
1158 }
1159 }
1160
1161 public void replace(FileLock fl1, FileLock fl2) {
1162 synchronized (lockList) {
1163 lockList.remove(fl1);
1164 lockList.add(fl2);
1165 }
1166 }
1167 }
1168
1169 // -- Native methods --
1170
1171 // Creates a new mapping
1172 private native long map0(int prot, long position, long length)
1173 throws IOException;
1174
1175 // Removes an existing mapping
1176 private static native int unmap0(long address, long length);
1177
1178 // Transfers from src to dst, or returns -2 if kernel can't do that
1179 private native long transferTo0(int src, long position, long count, int dst);
1180
1181 // Sets or reports this file's position
1182 // If offset is -1, the current position is returned
1183 // otherwise the position is set to offset
1184 private native long position0(FileDescriptor fd, long offset);
1185
1186 // Caches fieldIDs
1187 private static native long initIDs();
1188
1189 static {
1190 IOUtil.load();
1191 allocationGranularity = initIDs();
1192 }
1193
1194 }