/* * 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.commons.fileupload.util;import java.io.FilterInputStream;import java.io.IOException;import java.io.InputStream;/** * An input stream, which limits its data size. This stream is * used, if the content length is unknown. */public abstract class LimitedInputStream        extends FilterInputStream implements Closeable {    /**     * The maximum size of an item, in bytes.     */    private long sizeMax;    /**     * The current number of bytes.     */    private long count;    /**     * Whether this stream is already closed.     */    private boolean closed;    /**     * Creates a new instance.     * @param pIn The input stream, which shall be limited.     * @param pSizeMax The limit; no more than this number of bytes     *   shall be returned by the source stream.     */    public LimitedInputStream(InputStream pIn, long pSizeMax) {        super(pIn);        sizeMax = pSizeMax;    }    /**     * Called to indicate, that the input streams limit has     * been exceeded.     * @param pSizeMax The input streams limit, in bytes.     * @param pCount The actual number of bytes.     * @throws IOException The called method is expected     *   to raise an IOException.     */    protected abstract void raiseError(long pSizeMax, long pCount)            throws IOException;    /** Called to check, whether the input streams     * limit is reached.     * @throws IOException The given limit is exceeded.     */    private void checkLimit() throws IOException {        if (count > sizeMax) {            raiseError(sizeMax, count);        }    }    /**     * Reads the next byte of data from this input stream. The value     * byte is returned as an <code>int</code> in the range     * <code>0</code> to <code>255</code>. If no byte is available     * because the end of the stream has been reached, the value     * <code>-1</code> is returned. This method blocks until input data     * is available, the end of the stream is detected, or an exception     * is thrown.     * <p>     * This method     * simply performs <code>in.read()</code> and returns the result.     *     * @return     the next byte of data, or <code>-1</code> if the end of the     *             stream is reached.     * @exception  IOException  if an I/O error occurs.     * @see        java.io.FilterInputStream#in     */    public int read() throws IOException {        int res = super.read();        if (res != -1) {            count++;            checkLimit();        }        return res;    }    /**     * Reads up to <code>len</code> bytes of data from this input stream     * into an array of bytes. If <code>len</code> is not zero, the method     * blocks until some input is available; otherwise, no     * bytes are read and <code>0</code> is returned.     * <p>     * This method simply performs <code>in.read(b, off, len)</code>     * and returns the result.     *     * @param      b     the buffer into which the data is read.     * @param      off   The start offset in the destination array     *                   <code>b</code>.     * @param      len   the maximum number of bytes read.     * @return     the total number of bytes read into the buffer, or     *             <code>-1</code> if there is no more data because the end of     *             the stream has been reached.     * @exception  NullPointerException If <code>b</code> is <code>null</code>.     * @exception  IndexOutOfBoundsException If <code>off</code> is negative,     * <code>len</code> is negative, or <code>len</code> is greater than     * <code>b.length - off</code>     * @exception  IOException  if an I/O error occurs.     * @see        java.io.FilterInputStream#in     */    public int read(byte[] b, int off, int len) throws IOException {        int res = super.read(b, off, len);        if (res > 0) {            count += res;            checkLimit();        }        return res;    }    /**     * Returns, whether this stream is already closed.     * @return True, if the stream is closed, otherwise false.     * @throws IOException An I/O error occurred.     */    public boolean isClosed() throws IOException {        return closed;    }    /**     * Closes this input stream and releases any system resources     * associated with the stream.     * This     * method simply performs <code>in.close()</code>.     *     * @exception  IOException  if an I/O error occurs.     * @see        java.io.FilterInputStream#in     */    public void close() throws IOException {        closed = true;        super.close();    }}