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.fileupload.util; 018 019import java.io.FilterInputStream; 020import java.io.IOException; 021import 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 */ 027public abstract class LimitedInputStream extends FilterInputStream implements Closeable { 028 029 /** 030 * The maximum size of an item, in bytes. 031 */ 032 private final long sizeMax; 033 034 /** 035 * The current number of bytes. 036 */ 037 private long count; 038 039 /** 040 * Whether this stream is already closed. 041 */ 042 private boolean closed; 043 044 /** 045 * Creates a new instance. 046 * 047 * @param inputStream The input stream, which shall be limited. 048 * @param pSizeMax The limit; no more than this number of bytes 049 * shall be returned by the source stream. 050 */ 051 public LimitedInputStream(InputStream inputStream, long pSizeMax) { 052 super(inputStream); 053 sizeMax = pSizeMax; 054 } 055 056 /** 057 * Called to indicate, that the input streams limit has 058 * been exceeded. 059 * 060 * @param pSizeMax The input streams limit, in bytes. 061 * @param pCount The actual number of bytes. 062 * @throws IOException The called method is expected 063 * to raise an IOException. 064 */ 065 protected abstract void raiseError(long pSizeMax, long pCount) 066 throws IOException; 067 068 /** 069 * Called to check, whether the input streams 070 * limit is reached. 071 * 072 * @throws IOException The given limit is exceeded. 073 */ 074 private void checkLimit() throws IOException { 075 if (count > sizeMax) { 076 raiseError(sizeMax, count); 077 } 078 } 079 080 /** 081 * Reads the next byte of data from this input stream. The value 082 * byte is returned as an <code>int</code> in the range 083 * <code>0</code> to <code>255</code>. If no byte is available 084 * because the end of the stream has been reached, the value 085 * <code>-1</code> is returned. This method blocks until input data 086 * is available, the end of the stream is detected, or an exception 087 * is thrown. 088 * <p> 089 * This method 090 * simply performs <code>in.read()</code> and returns the result. 091 * 092 * @return the next byte of data, or <code>-1</code> if the end of the 093 * stream is reached. 094 * @throws IOException if an I/O error occurs. 095 * @see java.io.FilterInputStream#in 096 */ 097 @Override 098 public int read() throws IOException { 099 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}