001    /*
002     * Copyright (c) Andrey Kuznetsov. All Rights Reserved.
003     *
004     * http://uio.imagero.com
005     *
006     * Redistribution and use in source and binary forms, with or without
007     * modification, are permitted provided that the following conditions are met:
008     *
009     *  o Redistributions of source code must retain the above copyright notice,
010     *    this list of conditions and the following disclaimer.
011     *
012     *  o Redistributions in binary form must reproduce the above copyright notice,
013     *    this list of conditions and the following disclaimer in the documentation
014     *    and/or other materials provided with the distribution.
015     *
016     *  o Neither the name of Andrey Kuznetsov nor the names of
017     *    its contributors may be used to endorse or promote products derived
018     *    from this software without specific prior written permission.
019     *
020     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
021     * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
022     * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
023     * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
024     * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
025     * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
026     * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
027     * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
028     * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
029     * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
030     * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
031     */
032    
033    package com.imagero.uio.io;
034    
035    import java.io.FilterInputStream;
036    import java.io.IOException;
037    import java.io.InputStream;
038    
039    /**
040     * InputStream that reads specified number of bytes
041     *
042     * @author Kouznetsov Andrei
043     */
044    public class LimitedInputStream extends FilterInputStream {
045        protected int limit;
046    
047        /**
048         * create new LimitedInputStream
049         *
050         * @param in InputStream
051         * @param limit read limit
052         */
053        public LimitedInputStream(InputStream in, int limit) {
054            super(in);
055            this.limit = limit;
056        }
057    
058        public int available() throws IOException {
059            return limit;
060        }
061    
062        public int read() throws IOException {
063            if(limit-- <= 0) {
064                return -1;
065            }
066            return in.read();
067        }
068    
069        public int read(byte b[]) throws IOException {
070            return in.read(b, 0, b.length);
071        }
072    
073        public int read(byte b[], int off, int len) throws IOException {
074            if(limit > 0) {
075                int length = Math.min(len, limit);
076                int res = in.read(b, off, length);
077                if(res > 0) {
078                    limit -= res;
079                }
080                return res;
081            }
082            return -1;
083        }
084    
085        public long skip(long n) throws IOException {
086            if(limit > 0) {
087                long length = Math.min(n, limit);
088                long res = in.skip(length);
089                if(res > 0) {
090                    limit -= res;
091                }
092                return res;
093            }
094            return -1;
095        }
096    
097        int mark;
098    
099        public synchronized void mark(int readlimit) {
100            in.mark(readlimit);
101            mark = limit;
102        }
103    
104        public synchronized void reset() throws IOException {
105            in.reset();
106            limit = mark;
107        }
108    }