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/*
* Copyright 2013 Google Inc.
*
* Licensed 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 com.google.common.jimfs;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.primitives.Ints;
import java.io.IOException;
import java.io.InputStream;
/**
* {@link InputStream} for reading from a file's {@link RegularFile}.
*
* @author Colin Decker
*/
final class JimfsInputStream extends InputStream {
@GuardedBy("this")
@VisibleForTesting
RegularFile file;
@GuardedBy("this")
private long pos;
@GuardedBy("this")
private boolean finished;
private final FileSystemState fileSystemState;
public JimfsInputStream(RegularFile file, FileSystemState fileSystemState) {
this.file = checkNotNull(file);
this.fileSystemState = fileSystemState;
fileSystemState.register(this);
}
@Override
public synchronized int read() throws IOException {
checkNotClosed();
if (finished) {
return -1;
}
file.readLock().lock();
try {
int b = file.read(pos++); // it's ok for pos to go beyond size()
if (b == -1) {
finished = true;
} else {
file.updateAccessTime();
}
return b;
} finally {
file.readLock().unlock();
}
}
@Override
public int read(byte[] b) throws IOException {
return readInternal(b, 0, b.length);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
checkPositionIndexes(off, off + len, b.length);
return readInternal(b, off, len);
}
private synchronized int readInternal(byte[] b, int off, int len) throws IOException {
checkNotClosed();
if (finished) {
return -1;
}
file.readLock().lock();
try {
int read = file.read(pos, b, off, len);
if (read == -1) {
finished = true;
} else {
pos += read;
}
file.updateAccessTime();
return read;
} finally {
file.readLock().unlock();
}
}
@Override
public long skip(long n) throws IOException {
if (n <= 0) {
return 0;
}
synchronized (this) {
checkNotClosed();
if (finished) {
return 0;
}
// available() must be an int, so the min must be also
int skip = (int) Math.min(Math.max(file.size() - pos, 0), n);
pos += skip;
return skip;
}
}
@Override
public synchronized int available() throws IOException {
checkNotClosed();
if (finished) {
return 0;
}
long available = Math.max(file.size() - pos, 0);
return Ints.saturatedCast(available);
}
@GuardedBy("this")
private void checkNotClosed() throws IOException {
if (file == null) {
throw new IOException("stream is closed");
}
}
@Override
public synchronized void close() throws IOException {
if (isOpen()) {
fileSystemState.unregister(this);
file.closed();
// file is set to null here and only here
file = null;
}
}
@GuardedBy("this")
private boolean isOpen() {
return file != null;
}
}
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