001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.input;
018
019import java.io.IOException;
020import java.io.InputStream;
021
022/**
023 * This is a stream that will only supply bytes up to a certain length - if its
024 * position goes above that, it will stop.
025 * <p>
026 * This is useful to wrap ServletInputStreams. The ServletInputStream will block
027 * if you try to read content from it that isn't there, because it doesn't know
028 * whether the content hasn't arrived yet or whether the content has finished.
029 * So, one of these, initialized with the Content-length sent in the
030 * ServletInputStream's header, will stop it blocking, providing it's been sent
031 * with a correct content length.
032 *
033 * @version $Id: BoundedInputStream.java 1307462 2012-03-30 15:13:11Z ggregory $
034 * @since 2.0
035 */
036public class BoundedInputStream extends InputStream {
037
038    /** the wrapped input stream */
039    private final InputStream in;
040
041    /** the max length to provide */
042    private final long max;
043
044    /** the number of bytes already returned */
045    private long pos = 0;
046
047    /** the marked position */
048    private long mark = -1;
049
050    /** flag if close shoud be propagated */
051    private boolean propagateClose = true;
052
053    /**
054     * Creates a new <code>BoundedInputStream</code> that wraps the given input
055     * stream and limits it to a certain size.
056     *
057     * @param in The wrapped input stream
058     * @param size The maximum number of bytes to return
059     */
060    public BoundedInputStream(InputStream in, long size) {
061        // Some badly designed methods - eg the servlet API - overload length
062        // such that "-1" means stream finished
063        this.max = size;
064        this.in = in;
065    }
066
067    /**
068     * Creates a new <code>BoundedInputStream</code> that wraps the given input
069     * stream and is unlimited.
070     *
071     * @param in The wrapped input stream
072     */
073    public BoundedInputStream(InputStream in) {
074        this(in, -1);
075    }
076
077    /**
078     * Invokes the delegate's <code>read()</code> method if
079     * the current position is less than the limit.
080     * @return the byte read or -1 if the end of stream or
081     * the limit has been reached.
082     * @throws IOException if an I/O error occurs
083     */
084    @Override
085    public int read() throws IOException {
086        if (max >= 0 && pos >= max) {
087            return -1;
088        }
089        int result = in.read();
090        pos++;
091        return result;
092    }
093
094    /**
095     * Invokes the delegate's <code>read(byte[])</code> method.
096     * @param b the buffer to read the bytes into
097     * @return the number of bytes read or -1 if the end of stream or
098     * the limit has been reached.
099     * @throws IOException if an I/O error occurs
100     */
101    @Override
102    public int read(byte[] b) throws IOException {
103        return this.read(b, 0, b.length);
104    }
105
106    /**
107     * Invokes the delegate's <code>read(byte[], int, int)</code> method.
108     * @param b the buffer to read the bytes into
109     * @param off The start offset
110     * @param len The number of bytes to read
111     * @return the number of bytes read or -1 if the end of stream or
112     * the limit has been reached.
113     * @throws IOException if an I/O error occurs
114     */
115    @Override
116    public int read(byte[] b, int off, int len) throws IOException {
117        if (max>=0 && pos>=max) {
118            return -1;
119        }
120        long maxRead = max>=0 ? Math.min(len, max-pos) : len;
121        int bytesRead = in.read(b, off, (int)maxRead);
122
123        if (bytesRead==-1) {
124            return -1;
125        }
126
127        pos+=bytesRead;
128        return bytesRead;
129    }
130
131    /**
132     * Invokes the delegate's <code>skip(long)</code> method.
133     * @param n the number of bytes to skip
134     * @return the actual number of bytes skipped
135     * @throws IOException if an I/O error occurs
136     */
137    @Override
138    public long skip(long n) throws IOException {
139        long toSkip = max>=0 ? Math.min(n, max-pos) : n;
140        long skippedBytes = in.skip(toSkip);
141        pos+=skippedBytes;
142        return skippedBytes;
143    }
144
145    /**
146     * {@inheritDoc}
147     */
148    @Override
149    public int available() throws IOException {
150        if (max>=0 && pos>=max) {
151            return 0;
152        }
153        return in.available();
154    }
155
156    /**
157     * Invokes the delegate's <code>toString()</code> method.
158     * @return the delegate's <code>toString()</code>
159     */
160    @Override
161    public String toString() {
162        return in.toString();
163    }
164
165    /**
166     * Invokes the delegate's <code>close()</code> method
167     * if {@link #isPropagateClose()} is {@code true}.
168     * @throws IOException if an I/O error occurs
169     */
170    @Override
171    public void close() throws IOException {
172        if (propagateClose) {
173            in.close();
174        }
175    }
176
177    /**
178     * Invokes the delegate's <code>reset()</code> method.
179     * @throws IOException if an I/O error occurs
180     */
181    @Override
182    public synchronized void reset() throws IOException {
183        in.reset();
184        pos = mark;
185    }
186
187    /**
188     * Invokes the delegate's <code>mark(int)</code> method.
189     * @param readlimit read ahead limit
190     */
191    @Override
192    public synchronized void mark(int readlimit) {
193        in.mark(readlimit);
194        mark = pos;
195    }
196
197    /**
198     * Invokes the delegate's <code>markSupported()</code> method.
199     * @return true if mark is supported, otherwise false
200     */
201    @Override
202    public boolean markSupported() {
203        return in.markSupported();
204    }
205
206    /**
207     * Indicates whether the {@link #close()} method
208     * should propagate to the underling {@link InputStream}.
209     *
210     * @return {@code true} if calling {@link #close()}
211     * propagates to the <code>close()</code> method of the
212     * underlying stream or {@code false} if it does not.
213     */
214    public boolean isPropagateClose() {
215        return propagateClose;
216    }
217
218    /**
219     * Set whether the {@link #close()} method
220     * should propagate to the underling {@link InputStream}.
221     *
222     * @param propagateClose {@code true} if calling
223     * {@link #close()} propagates to the <code>close()</code>
224     * method of the underlying stream or
225     * {@code false} if it does not.
226     */
227    public void setPropagateClose(boolean propagateClose) {
228        this.propagateClose = propagateClose;
229    }
230}