org.xnio.conduits.FixedLengthStreamSourceConduit Maven / Gradle / Ivy
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*
* Copyright 2013 Red Hat, Inc. and/or its affiliates.
*
* 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.conduits;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import org.xnio.channels.StreamSinkChannel;
/**
* A stream source conduit which limits the length of input.
*
* @author David M. Lloyd
*/
public final class FixedLengthStreamSourceConduit extends AbstractStreamSourceConduit implements StreamSourceConduit {
private long remaining;
/**
* Construct a new instance.
*
* @param next the conduit to limit
* @param remaining the number of bytes to limit to
*/
public FixedLengthStreamSourceConduit(final StreamSourceConduit next, final long remaining) {
super(next);
this.remaining = remaining;
}
public long transferTo(final long position, final long count, final FileChannel target) throws IOException {
long length = this.remaining;
if (length > 0) {
final long res = next.transferTo(position, Math.min(count, length), target);
if (res > 0L) {
this.remaining = length - res;
}
return res;
} else {
return 0;
}
}
public long transferTo(final long count, final ByteBuffer throughBuffer, final StreamSinkChannel target) throws IOException {
long length = this.remaining;
if (length > 0) {
final long res = next.transferTo(Math.min(count, length), throughBuffer, target);
if (res > 0L) {
this.remaining = length - res;
}
return res;
} else {
return -1L;
}
}
public int read(final ByteBuffer dst) throws IOException {
final int limit = dst.limit();
final int pos = dst.position();
final int res;
final long length = this.remaining;
if (length == 0L) {
return -1;
}
if (limit - pos > length) {
dst.limit(pos + (int) length);
try {
res = next.read(dst);
} finally {
dst.limit(limit);
}
} else {
res = next.read(dst);
}
if (res > 0L) {
this.remaining = length - res;
}
return res;
}
public long read(final ByteBuffer[] dsts, final int offs, final int len) throws IOException {
if (len == 0) {
return 0L;
} else if (len == 1) {
return read(dsts[offs]);
}
final long length = this.remaining;
if (length == 0L) {
return -1L;
}
long res;
int lim;
// The total amount of buffer space discovered so far.
long t = 0L;
for (int i = 0; i < length; i ++) {
final ByteBuffer buffer = dsts[i + offs];
// Grow the discovered buffer space by the remaining size of the current buffer.
// We want to capture the limit so we calculate "remaining" ourselves.
t += (lim = buffer.limit()) - buffer.position();
if (t > length) {
// only read up to this point, and trim the last buffer by the number of extra bytes
buffer.limit(lim - (int) (t - length));
try {
res = next.read(dsts, offs, i + 1);
if (res > 0L) {
this.remaining = length - res;
}
return res;
} finally {
// restore the original limit
buffer.limit(lim);
}
}
}
// the total buffer space is less than the remaining count.
res = t == 0L ? 0L : next.read(dsts, offs, len);
if (res > 0L) {
this.remaining = length - res;
}
return res;
}
/**
* Get the number of bytes which remain available to read.
*
* @return the number of bytes which remain available to read
*/
public long getRemaining() {
return remaining;
}
}