/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on May 25, 2011
*/
package com.bigdata.io;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* A stream which only lets you read a fixed #of bytes from an underlying
* stream.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public class SliceInputStream extends FilterInputStream {
final private int limit;
private int nread = 0;
/**
* @param in
* The source stream.
* @param limit
* The maximum #of bytes which may be read.
*/
public SliceInputStream(final InputStream in, final int limit) {
super(in);
if (in == null)
throw new IllegalArgumentException();
if (limit < 0)
throw new IllegalArgumentException();
this.limit = limit;
}
@Override
public int read() throws IOException {
if (nread >= limit)
return -1;
final int b = in.read();
if (b == -1)
return -1;
nread++;
return b;
}
@Override
public int read(final byte[] b, final int off, final int len)
throws IOException {
if (off < 0)
throw new IllegalArgumentException();
if (len < 0)
throw new IllegalArgumentException();
if (off + len > b.length)
throw new IllegalArgumentException();
final int nremaining = limit - nread;
final int nrequested = len - off;
if (nremaining == 0 && nrequested > 0) {
// EOF
return -1;
}
final int nallowed = Math.min(nremaining, nrequested);
final int n = in.read(b, off, nallowed);
if (n == -1)
return -1;
nread += n;
return n;
}
}