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java.nio.FileChannelImpl Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.nio;
import java.io.Closeable;
import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.NonReadableChannelException;
import java.nio.channels.NonWritableChannelException;
import java.nio.channels.OverlappingFileLockException;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.util.Arrays;
import java.util.Comparator;
import java.util.SortedSet;
import java.util.TreeSet;
import libcore.io.ErrnoException;
import libcore.io.Libcore;
import libcore.io.StructFlock;
import libcore.util.MutableLong;
import static libcore.io.OsConstants.*;
/**
* Our concrete implementation of the abstract FileChannel class.
*/
final class FileChannelImpl extends FileChannel {
private static final Comparator LOCK_COMPARATOR = new Comparator() {
public int compare(FileLock lock1, FileLock lock2) {
long position1 = lock1.position();
long position2 = lock2.position();
return position1 > position2 ? 1 : (position1 < position2 ? -1 : 0);
}
};
private final Object stream;
private final FileDescriptor fd;
private final int mode;
// The set of acquired and pending locks.
private final SortedSet locks = new TreeSet(LOCK_COMPARATOR);
/**
* Create a new file channel implementation class that wraps the given
* fd and operates in the specified mode.
*/
public FileChannelImpl(Object stream, FileDescriptor fd, int mode) {
this.fd = fd;
this.stream = stream;
this.mode = mode;
}
private void checkOpen() throws ClosedChannelException {
if (!isOpen()) {
throw new ClosedChannelException();
}
}
private void checkReadable() {
if ((mode & O_ACCMODE) == O_WRONLY) {
throw new NonReadableChannelException();
}
}
private void checkWritable() {
if ((mode & O_ACCMODE) == O_RDONLY) {
throw new NonWritableChannelException();
}
}
protected void implCloseChannel() throws IOException {
if (stream instanceof Closeable) {
((Closeable) stream).close();
}
}
private FileLock basicLock(long position, long size, boolean shared, boolean wait) throws IOException {
int accessMode = (mode & O_ACCMODE);
if (accessMode == O_RDONLY) {
if (!shared) {
throw new NonWritableChannelException();
}
} else if (accessMode == O_WRONLY) {
if (shared) {
throw new NonReadableChannelException();
}
}
if (position < 0 || size < 0) {
throw new IllegalArgumentException("position=" + position + " size=" + size);
}
FileLock pendingLock = new FileLockImpl(this, position, size, shared);
addLock(pendingLock);
StructFlock flock = new StructFlock();
flock.l_type = (short) (shared ? F_RDLCK : F_WRLCK);
flock.l_whence = (short) SEEK_SET;
flock.l_start = position;
flock.l_len = translateLockLength(size);
boolean success = false;
try {
success = (Libcore.os.fcntlFlock(fd, wait ? F_SETLKW64 : F_SETLK64, flock) != -1);
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
} finally {
if (!success) {
removeLock(pendingLock);
}
}
return success ? pendingLock : null;
}
private static long translateLockLength(long byteCount) {
// FileChannel uses Long.MAX_VALUE to mean "lock the whole file" where POSIX uses 0.
return (byteCount == Long.MAX_VALUE) ? 0 : byteCount;
}
private static final class FileLockImpl extends FileLock {
private boolean isReleased = false;
public FileLockImpl(FileChannel channel, long position, long size, boolean shared) {
super(channel, position, size, shared);
}
public boolean isValid() {
return !isReleased && channel().isOpen();
}
public void release() throws IOException {
if (!channel().isOpen()) {
throw new ClosedChannelException();
}
if (!isReleased) {
((FileChannelImpl) channel()).release(this);
isReleased = true;
}
}
}
public final FileLock lock(long position, long size, boolean shared) throws IOException {
checkOpen();
FileLock resultLock = null;
{
boolean completed = false;
try {
begin();
resultLock = basicLock(position, size, shared, true);
completed = true;
} finally {
end(completed);
}
}
return resultLock;
}
public final FileLock tryLock(long position, long size, boolean shared) throws IOException {
checkOpen();
return basicLock(position, size, shared, false);
}
/**
* Non-API method to release a given lock on a file channel. Assumes that
* the lock will mark itself invalid after successful unlocking.
*/
public void release(FileLock lock) throws IOException {
checkOpen();
StructFlock flock = new StructFlock();
flock.l_type = (short) F_UNLCK;
flock.l_whence = (short) SEEK_SET;
flock.l_start = lock.position();
flock.l_len = translateLockLength(lock.size());
try {
Libcore.os.fcntlFlock(fd, F_SETLKW64, flock);
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
removeLock(lock);
}
public void force(boolean metadata) throws IOException {
checkOpen();
if ((mode & O_ACCMODE) != O_RDONLY) {
try {
if (metadata) {
Libcore.os.fsync(fd);
} else {
Libcore.os.fdatasync(fd);
}
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
}
}
public final MappedByteBuffer map(MapMode mapMode, long position, long size) throws IOException {
checkOpen();
if (mapMode == null) {
throw new NullPointerException("mapMode == null");
}
if (position < 0 || size < 0 || size > Integer.MAX_VALUE) {
throw new IllegalArgumentException("position=" + position + " size=" + size);
}
int accessMode = (mode & O_ACCMODE);
if (accessMode == O_RDONLY) {
if (mapMode != MapMode.READ_ONLY) {
throw new NonWritableChannelException();
}
} else if (accessMode == O_WRONLY) {
throw new NonReadableChannelException();
}
if (position + size > size()) {
// We can't defer to FileChannel.truncate because that will only make a file shorter,
// and we only care about making our backing file longer here.
try {
Libcore.os.ftruncate(fd, position + size);
} catch (ErrnoException ftruncateException) {
// EINVAL can be thrown if we're dealing with non-regular
// files, for example, character devices such as /dev/zero.
// In those cases, we ignore the failed truncation and
// continue on.
try {
if (S_ISREG(Libcore.os.fstat(fd).st_mode) || ftruncateException.errno != EINVAL) {
throw ftruncateException.rethrowAsIOException();
}
} catch (ErrnoException fstatException) {
throw fstatException.rethrowAsIOException();
}
}
}
long alignment = position - position % Libcore.os.sysconf(_SC_PAGE_SIZE);
int offset = (int) (position - alignment);
MemoryBlock block = MemoryBlock.mmap(fd, alignment, size + offset, mapMode);
return new DirectByteBuffer(block, (int) size, offset, (mapMode == MapMode.READ_ONLY), mapMode);
}
public long position() throws IOException {
checkOpen();
try {
return Libcore.os.lseek(fd, 0L, SEEK_CUR);
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
}
public FileChannel position(long newPosition) throws IOException {
checkOpen();
if (newPosition < 0) {
throw new IllegalArgumentException("position: " + newPosition);
}
try {
Libcore.os.lseek(fd, newPosition, SEEK_SET);
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
return this;
}
public int read(ByteBuffer buffer, long position) throws IOException {
if (position < 0) {
throw new IllegalArgumentException("position: " + position);
}
return readImpl(buffer, position);
}
public int read(ByteBuffer buffer) throws IOException {
return readImpl(buffer, -1);
}
private int readImpl(ByteBuffer buffer, long position) throws IOException {
buffer.checkWritable();
checkOpen();
checkReadable();
if (!buffer.hasRemaining()) {
return 0;
}
int bytesRead = 0;
boolean completed = false;
try {
begin();
try {
if (position == -1) {
bytesRead = Libcore.os.read(fd, buffer);
} else {
bytesRead = Libcore.os.pread(fd, buffer, position);
}
if (bytesRead == 0) {
bytesRead = -1;
}
} catch (ErrnoException errnoException) {
if (errnoException.errno == EAGAIN) {
// We don't throw if we try to read from an empty non-blocking pipe.
bytesRead = 0;
} else {
throw errnoException.rethrowAsIOException();
}
}
completed = true;
} finally {
end(completed && bytesRead >= 0);
}
if (bytesRead > 0) {
buffer.position(buffer.position() + bytesRead);
}
return bytesRead;
}
private int transferIoVec(IoVec ioVec) throws IOException {
if (ioVec.init() == 0) {
return 0;
}
int bytesTransferred = 0;
boolean completed = false;
try {
begin();
bytesTransferred = ioVec.doTransfer(fd);
completed = true;
} finally {
end(completed);
}
ioVec.didTransfer(bytesTransferred);
return bytesTransferred;
}
public long read(ByteBuffer[] buffers, int offset, int length) throws IOException {
Arrays.checkOffsetAndCount(buffers.length, offset, length);
checkOpen();
checkReadable();
return transferIoVec(new IoVec(buffers, offset, length, IoVec.Direction.READV));
}
public long size() throws IOException {
checkOpen();
try {
return Libcore.os.fstat(fd).st_size;
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
}
public long transferFrom(ReadableByteChannel src, long position, long count) throws IOException {
checkOpen();
if (!src.isOpen()) {
throw new ClosedChannelException();
}
checkWritable();
if (position < 0 || count < 0 || count > Integer.MAX_VALUE) {
throw new IllegalArgumentException("position=" + position + " count=" + count);
}
if (position > size()) {
return 0;
}
// Although sendfile(2) originally supported writing to a regular file.
// In Linux 2.6 and later, it only supports writing to sockets.
// If our source is a regular file, mmap(2) rather than reading.
// Callers should only be using transferFrom for large transfers,
// so the mmap(2) overhead isn't a concern.
if (src instanceof FileChannel) {
FileChannel fileSrc = (FileChannel) src;
long size = fileSrc.size();
long filePosition = fileSrc.position();
count = Math.min(count, size - filePosition);
ByteBuffer buffer = fileSrc.map(MapMode.READ_ONLY, filePosition, count);
try {
fileSrc.position(filePosition + count);
return write(buffer, position);
} finally {
NioUtils.freeDirectBuffer(buffer);
}
}
// For non-file channels, all we can do is read and write via userspace.
ByteBuffer buffer = ByteBuffer.allocate((int) count);
src.read(buffer);
buffer.flip();
return write(buffer, position);
}
public long transferTo(long position, long count, WritableByteChannel target) throws IOException {
checkOpen();
if (!target.isOpen()) {
throw new ClosedChannelException();
}
checkReadable();
if (target instanceof FileChannelImpl) {
((FileChannelImpl) target).checkWritable();
}
if (position < 0 || count < 0) {
throw new IllegalArgumentException("position=" + position + " count=" + count);
}
if (count == 0 || position >= size()) {
return 0;
}
count = Math.min(count, size() - position);
// Try sendfile(2) first...
boolean completed = false;
if (target instanceof SocketChannelImpl) {
FileDescriptor outFd = ((SocketChannelImpl) target).getFD();
try {
begin();
try {
MutableLong offset = new MutableLong(position);
long rc = Libcore.os.sendfile(outFd, fd, offset, count);
completed = true;
return rc;
} catch (ErrnoException errnoException) {
// If the OS doesn't support what we asked for, we want to fall through and
// try a different approach. If it does support it, but it failed, we're done.
if (errnoException.errno != ENOSYS && errnoException.errno != EINVAL) {
throw errnoException.rethrowAsIOException();
}
}
} finally {
end(completed);
}
}
// ...fall back to write(2).
ByteBuffer buffer = null;
try {
buffer = map(MapMode.READ_ONLY, position, count);
return target.write(buffer);
} finally {
NioUtils.freeDirectBuffer(buffer);
}
}
public FileChannel truncate(long size) throws IOException {
checkOpen();
if (size < 0) {
throw new IllegalArgumentException("size < 0: " + size);
}
checkWritable();
if (size < size()) {
try {
Libcore.os.ftruncate(fd, size);
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
}
return this;
}
public int write(ByteBuffer buffer, long position) throws IOException {
if (position < 0) {
throw new IllegalArgumentException("position < 0: " + position);
}
return writeImpl(buffer, position);
}
public int write(ByteBuffer buffer) throws IOException {
return writeImpl(buffer, -1);
}
private int writeImpl(ByteBuffer buffer, long position) throws IOException {
checkOpen();
checkWritable();
if (buffer == null) {
throw new NullPointerException("buffer == null");
}
if (!buffer.hasRemaining()) {
return 0;
}
int bytesWritten = 0;
boolean completed = false;
try {
begin();
try {
if (position == -1) {
bytesWritten = Libcore.os.write(fd, buffer);
} else {
bytesWritten = Libcore.os.pwrite(fd, buffer, position);
}
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
completed = true;
} finally {
end(completed);
}
if (bytesWritten > 0) {
buffer.position(buffer.position() + bytesWritten);
}
return bytesWritten;
}
public long write(ByteBuffer[] buffers, int offset, int length) throws IOException {
Arrays.checkOffsetAndCount(buffers.length, offset, length);
checkOpen();
checkWritable();
return transferIoVec(new IoVec(buffers, offset, length, IoVec.Direction.WRITEV));
}
/**
* @param copyingIn true if we're copying data into the buffers (typically
* because the caller is a file/network read operation), false if we're
* copying data out of the buffers (for a file/network write operation).
*/
static int calculateTotalRemaining(ByteBuffer[] buffers, int offset, int length, boolean copyingIn) {
int count = 0;
for (int i = offset; i < offset + length; ++i) {
count += buffers[i].remaining();
if (copyingIn) {
buffers[i].checkWritable();
}
}
return count;
}
public FileDescriptor getFD() {
return fd;
}
/**
* Add a new pending lock to the manager. Throws an exception if the lock
* would overlap an existing lock. Once the lock is acquired it remains in
* this set as an acquired lock.
*/
private synchronized void addLock(FileLock lock) throws OverlappingFileLockException {
long lockEnd = lock.position() + lock.size();
for (FileLock existingLock : locks) {
if (existingLock.position() > lockEnd) {
// This, and all remaining locks, start beyond our end (so
// cannot overlap).
break;
}
if (existingLock.overlaps(lock.position(), lock.size())) {
throw new OverlappingFileLockException();
}
}
locks.add(lock);
}
/**
* Removes an acquired lock from the lock manager. If the lock did not exist
* in the lock manager the operation is a no-op.
*/
private synchronized void removeLock(FileLock lock) {
locks.remove(lock);
}
}
