1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.fileupload.util;
18
19 import java.io.FilterInputStream;
20 import java.io.IOException;
21 import java.io.InputStream;
22
23 /**
24 * An input stream, which limits its data size. This stream is
25 * used, if the content length is unknown.
26 */
27 public abstract class LimitedInputStream extends FilterInputStream implements Closeable {
28
29 /**
30 * The maximum size of an item, in bytes.
31 */
32 private final long sizeMax;
33
34 /**
35 * The current number of bytes.
36 */
37 private long count;
38
39 /**
40 * Whether this stream is already closed.
41 */
42 private boolean closed;
43
44 /**
45 * Creates a new instance.
46 *
47 * @param inputStream The input stream, which shall be limited.
48 * @param pSizeMax The limit; no more than this number of bytes
49 * shall be returned by the source stream.
50 */
51 public LimitedInputStream(InputStream inputStream, long pSizeMax) {
52 super(inputStream);
53 sizeMax = pSizeMax;
54 }
55
56 /**
57 * Called to indicate, that the input streams limit has
58 * been exceeded.
59 *
60 * @param pSizeMax The input streams limit, in bytes.
61 * @param pCount The actual number of bytes.
62 * @throws IOException The called method is expected
63 * to raise an IOException.
64 */
65 protected abstract void raiseError(long pSizeMax, long pCount)
66 throws IOException;
67
68 /**
69 * Called to check, whether the input streams
70 * limit is reached.
71 *
72 * @throws IOException The given limit is exceeded.
73 */
74 private void checkLimit() throws IOException {
75 if (count > sizeMax) {
76 raiseError(sizeMax, count);
77 }
78 }
79
80 /**
81 * Reads the next byte of data from this input stream. The value
82 * byte is returned as an <code>int</code> in the range
83 * <code>0</code> to <code>255</code>. If no byte is available
84 * because the end of the stream has been reached, the value
85 * <code>-1</code> is returned. This method blocks until input data
86 * is available, the end of the stream is detected, or an exception
87 * is thrown.
88 * <p>
89 * This method
90 * simply performs <code>in.read()</code> and returns the result.
91 *
92 * @return the next byte of data, or <code>-1</code> if the end of the
93 * stream is reached.
94 * @throws IOException if an I/O error occurs.
95 * @see java.io.FilterInputStream#in
96 */
97 @Override
98 public int read() throws IOException {
99 int res = super.read();
100 if (res != -1) {
101 count++;
102 checkLimit();
103 }
104 return res;
105 }
106
107 /**
108 * Reads up to <code>len</code> bytes of data from this input stream
109 * into an array of bytes. If <code>len</code> is not zero, the method
110 * blocks until some input is available; otherwise, no
111 * bytes are read and <code>0</code> is returned.
112 * <p>
113 * This method simply performs <code>in.read(b, off, len)</code>
114 * and returns the result.
115 *
116 * @param b the buffer into which the data is read.
117 * @param off The start offset in the destination array
118 * <code>b</code>.
119 * @param len the maximum number of bytes read.
120 * @return the total number of bytes read into the buffer, or
121 * <code>-1</code> if there is no more data because the end of
122 * the stream has been reached.
123 * @throws NullPointerException If <code>b</code> is <code>null</code>.
124 * @throws IndexOutOfBoundsException If <code>off</code> is negative,
125 * <code>len</code> is negative, or <code>len</code> is greater than
126 * <code>b.length - off</code>
127 * @throws IOException if an I/O error occurs.
128 * @see java.io.FilterInputStream#in
129 */
130 @Override
131 public int read(byte[] b, int off, int len) throws IOException {
132 int res = super.read(b, off, len);
133 if (res > 0) {
134 count += res;
135 checkLimit();
136 }
137 return res;
138 }
139
140 /**
141 * Returns, whether this stream is already closed.
142 *
143 * @return True, if the stream is closed, otherwise false.
144 * @throws IOException An I/O error occurred.
145 */
146 @Override
147 public boolean isClosed() throws IOException {
148 return closed;
149 }
150
151 /**
152 * Closes this input stream and releases any system resources
153 * associated with the stream.
154 * This
155 * method simply performs <code>in.close()</code>.
156 *
157 * @throws IOException if an I/O error occurs.
158 * @see java.io.FilterInputStream#in
159 */
160 @Override
161 public void close() throws IOException {
162 closed = true;
163 super.close();
164 }
165
166 }