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: */
017: package org.apache.commons.fileupload.util;
018:
019: import java.io.FilterInputStream;
020: import java.io.IOException;
021: import java.io.InputStream;
022:
023: /**
024: * An input stream, which limits its data size. This stream is
025: * used, if the content length is unknown.
026: */
027: public abstract class LimitedInputStream extends FilterInputStream
028: implements Closeable {
029: /**
030: * The maximum size of an item, in bytes.
031: */
032: private long sizeMax;
033: /**
034: * The current number of bytes.
035: */
036: private long count;
037: /**
038: * Whether this stream is already closed.
039: */
040: private boolean closed;
041:
042: /**
043: * Creates a new instance.
044: * @param pIn The input stream, which shall be limited.
045: * @param pSizeMax The limit; no more than this number of bytes
046: * shall be returned by the source stream.
047: */
048: public LimitedInputStream(InputStream pIn, long pSizeMax) {
049: super (pIn);
050: sizeMax = pSizeMax;
051: }
052:
053: /**
054: * Called to indicate, that the input streams limit has
055: * been exceeded.
056: * @param pSizeMax The input streams limit, in bytes.
057: * @param pCount The actual number of bytes.
058: * @throws IOException The called method is expected
059: * to raise an IOException.
060: */
061: protected abstract void raiseError(long pSizeMax, long pCount)
062: throws IOException;
063:
064: /** Called to check, whether the input streams
065: * limit is reached.
066: * @throws IOException The given limit is exceeded.
067: */
068: private void checkLimit() throws IOException {
069: if (count > sizeMax) {
070: raiseError(sizeMax, count);
071: }
072: }
073:
074: /**
075: * Reads the next byte of data from this input stream. The value
076: * byte is returned as an <code>int</code> in the range
077: * <code>0</code> to <code>255</code>. If no byte is available
078: * because the end of the stream has been reached, the value
079: * <code>-1</code> is returned. This method blocks until input data
080: * is available, the end of the stream is detected, or an exception
081: * is thrown.
082: * <p>
083: * This method
084: * simply performs <code>in.read()</code> and returns the result.
085: *
086: * @return the next byte of data, or <code>-1</code> if the end of the
087: * stream is reached.
088: * @exception IOException if an I/O error occurs.
089: * @see java.io.FilterInputStream#in
090: */
091: public int read() throws IOException {
092: int res = super .read();
093: if (res != -1) {
094: count++;
095: checkLimit();
096: }
097: return res;
098: }
099:
100: /**
101: * Reads up to <code>len</code> bytes of data from this input stream
102: * into an array of bytes. If <code>len</code> is not zero, the method
103: * blocks until some input is available; otherwise, no
104: * bytes are read and <code>0</code> is returned.
105: * <p>
106: * This method simply performs <code>in.read(b, off, len)</code>
107: * and returns the result.
108: *
109: * @param b the buffer into which the data is read.
110: * @param off The start offset in the destination array
111: * <code>b</code>.
112: * @param len the maximum number of bytes read.
113: * @return the total number of bytes read into the buffer, or
114: * <code>-1</code> if there is no more data because the end of
115: * the stream has been reached.
116: * @exception NullPointerException If <code>b</code> is <code>null</code>.
117: * @exception IndexOutOfBoundsException If <code>off</code> is negative,
118: * <code>len</code> is negative, or <code>len</code> is greater than
119: * <code>b.length - off</code>
120: * @exception IOException if an I/O error occurs.
121: * @see java.io.FilterInputStream#in
122: */
123: public int read(byte[] b, int off, int len) throws IOException {
124: int res = super .read(b, off, len);
125: if (res > 0) {
126: count += res;
127: checkLimit();
128: }
129: return res;
130: }
131:
132: /**
133: * Returns, whether this stream is already closed.
134: * @return True, if the stream is closed, otherwise false.
135: * @throws IOException An I/O error occurred.
136: */
137: public boolean isClosed() throws IOException {
138: return closed;
139: }
140:
141: /**
142: * Closes this input stream and releases any system resources
143: * associated with the stream.
144: * This
145: * method simply performs <code>in.close()</code>.
146: *
147: * @exception IOException if an I/O error occurs.
148: * @see java.io.FilterInputStream#in
149: */
150: public void close() throws IOException {
151: closed = true;
152: super.close();
153: }
154: }
|