org.xnio.streams.LimitedInputStream Maven / Gradle / Ivy
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*
* Copyright 2010 Red Hat, Inc. and/or its affiliates, and individual
* contributors as indicated by the @author tags.
*
* 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 org.xnio.streams;
import static org.xnio._private.Messages.msg;
import java.io.IOException;
import java.io.InputStream;
/**
* An input stream which truncates the underlying stream to the given length.
*
* @author David M. Lloyd
*/
public final class LimitedInputStream extends InputStream {
private final InputStream delegate;
private long remaining;
private long mark = -1L;
/**
* Construct a new instance.
*
* @param delegate the delegate stream
* @param size the maximum size to pass
*/
public LimitedInputStream(final InputStream delegate, final long size) {
this.delegate = delegate;
remaining = size;
}
/** {@inheritDoc} */
public int read() throws IOException {
final long remaining = this.remaining;
if (remaining > 0) {
final int b = delegate.read();
if (b >= 0) this.remaining = remaining - 1;
return b;
} else {
return -1;
}
}
/** {@inheritDoc} */
public int read(final byte[] b, final int off, final int len) throws IOException {
final long remaining = this.remaining;
if (remaining == 0L) {
return -1;
}
final int cnt = delegate.read(b, off, (int) Math.min((long)len, remaining));
if (cnt == -1) {
return -1;
}
this.remaining = remaining - cnt;
return cnt;
}
/** {@inheritDoc} */
public long skip(final long n) throws IOException {
final long remaining = this.remaining;
if (remaining == 0L || n <= 0L) {
return 0L;
}
final long cnt = delegate.skip(Math.min(n, remaining));
if (cnt > 0L) {
this.remaining = remaining - cnt;
}
return cnt;
}
/** {@inheritDoc} */
public int available() throws IOException {
return Math.min(delegate.available(), (int) Math.min((long)Integer.MAX_VALUE, remaining));
}
/** {@inheritDoc} */
public void close() throws IOException {
remaining = 0;
delegate.close();
}
/** {@inheritDoc} */
public void mark(final int limit) {
if (markSupported()) {
delegate.mark(limit);
mark = remaining;
}
}
/** {@inheritDoc} */
public void reset() throws IOException {
final long mark = this.mark;
if (mark == -1L) {
throw msg.markNotSet();
}
delegate.reset();
remaining = mark;
}
/** {@inheritDoc} */
public boolean markSupported() {
return delegate.markSupported();
}
}