FixedLengthInputStream.java

/*
 * This file is part of the OWASP Proxy, a free intercepting proxy library.
 * Copyright (C) 2008-2010 Rogan Dawes <rogan@dawes.za.net>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to:
 * The Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

package org.owasp.proxy.io;

import java.io.IOException;
import java.io.InputStream;

import java.io.FilterInputStream;

public class FixedLengthInputStream extends FilterInputStream {

    private int max;

    private int read = 0;

    private boolean closed = false;

    public FixedLengthInputStream(InputStream is, int max) {
        super(is);
        this.max = max;
    }

    public int available() throws IOException {
        if (closed) {
            throw new IOException("available called on closed stream");
        }
        int canread = max - read;
        int available = super.available();
        if (canread > available) {
            available = canread;
        }
        return available;
    }

    public void close() {
        closed = true;
    }

    public void mark(int readlimit) {
        super.mark(readlimit);
    }

    public boolean markSupported() {
        return super.markSupported();
    }

    public int read() throws IOException {
        if (closed) {
            throw new IOException("read called on closed stream");
        }
        int canread = max - read;
        if (canread < 1) {
            canread = 0;
        }
        if (canread > 0) {
            int b = super.read();
            if (b > -1) {
                read++;
            }
            return b;
        } else {
            return -1;
        }
    }

    public int read(byte[] b) throws IOException {
        return read(b, 0, b.length);
    }

    public int read(byte[] b, int off, int len) throws IOException {
        if (closed) {
            throw new IOException("read called on closed stream");
        }
        int canread = Math.min(len, max - read);
        if (canread > 0) {
            int bytesRead = super.read(b, off, canread);
            if (bytesRead > -1) {
                read = read + bytesRead;
            }
            return bytesRead;
        } else {
            return -1;
        }
    }

    public long skip(long n) throws IOException {
        if (closed) {
            throw new IOException("skip called on closed stream");
        }
        int canread = max - read;
        if (n > canread) {
            n = canread;
        }
        if (n > 0) {
            n = super.skip(n);
            read = read + (int) n;
        }
        return n;
    }

    public String toString() {
        return this.getClass().getName() + " on a "
                + super.in.getClass().getName() + " (" + read + " of " + max
                + ")";
    }
}