/*
* 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 org.apache.jena.hadoop.rdf.io.input.util;
import java.io.IOException;
import java.io.InputStream;
/**
* A block input stream which can is a wrapper around another input stream which
* restricts reading to a specific number of bytes and can report the number of
* bytes read
* <p>
* The class assumes that the underlying input stream has already been seeked to
* the appropriate start point
* </p>
*
*
*
*/
public final class BlockInputStream extends TrackedInputStream {
private long limit = Long.MAX_VALUE;
/**
* Creates a new tracked input stream
*
* @param input
* Input stream to track
* @param limit
* Maximum number of bytes to read from the stream
*/
public BlockInputStream(InputStream input, long limit) {
super(input);
if (limit < 0)
throw new IllegalArgumentException("limit must be >= 0");
this.limit = limit;
}
@Override
public int read() throws IOException {
if (this.bytesRead >= this.limit) {
return -1;
}
return super.read();
}
@Override
public int available() throws IOException {
if (this.bytesRead >= this.limit) {
return 0;
}
return super.available();
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (len == 0) {
return 0;
} else if (this.bytesRead >= this.limit) {
return -1;
} else if (len > this.limit - this.bytesRead) {
len = (int) (this.limit - this.bytesRead);
}
return super.read(b, off, len);
}
@Override
public long skip(long n) throws IOException {
if (n == 0) {
return 0;
} else if (this.bytesRead >= this.limit) {
return -1;
} else if (n > this.limit - this.bytesRead) {
n = this.limit - this.bytesRead;
}
return super.skip(n);
}
}