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 018package org.apache.commons.net.io; 019 020import java.io.FilterInputStream; 021import java.io.IOException; 022import java.io.InputStream; 023 024/** 025 * This class wraps an input stream, replacing all singly occurring 026 * <LF> (linefeed) characters with <CR><LF> (carriage return 027 * followed by linefeed), which is the NETASCII standard for representing 028 * a newline. 029 * You would use this class to implement ASCII file transfers requiring 030 * conversion to NETASCII. 031 * 032 * 033 */ 034 035public final class ToNetASCIIInputStream extends FilterInputStream 036{ 037 private static final int NOTHING_SPECIAL = 0; 038 private static final int LAST_WAS_CR = 1; 039 private static final int LAST_WAS_NL = 2; 040 private int status; 041 042 /** 043 * Creates a ToNetASCIIInputStream instance that wraps an existing 044 * InputStream. 045 * 046 * @param input The InputStream to wrap. 047 */ 048 public ToNetASCIIInputStream(final InputStream input) 049 { 050 super(input); 051 status = NOTHING_SPECIAL; 052 } 053 054 055 /** 056 * Reads and returns the next byte in the stream. If the end of the 057 * message has been reached, returns -1. 058 * 059 * @return The next character in the stream. Returns -1 if the end of the 060 * stream has been reached. 061 * @throws IOException If an error occurs while reading the underlying 062 * stream. 063 */ 064 @Override 065 public int read() throws IOException 066 { 067 final int ch; 068 069 if (status == LAST_WAS_NL) 070 { 071 status = NOTHING_SPECIAL; 072 return '\n'; 073 } 074 075 ch = in.read(); 076 077 switch (ch) 078 { 079 case '\r': 080 status = LAST_WAS_CR; 081 return '\r'; 082 case '\n': 083 if (status != LAST_WAS_CR) 084 { 085 status = LAST_WAS_NL; 086 return '\r'; 087 } 088 //$FALL-THROUGH$ 089 default: 090 status = NOTHING_SPECIAL; 091 return ch; 092 } 093 // statement not reached 094 //return ch; 095 } 096 097 098 /** 099 * Reads the next number of bytes from the stream into an array and 100 * returns the number of bytes read. Returns -1 if the end of the 101 * stream has been reached. 102 * 103 * @param buffer The byte array in which to store the data. 104 * @return The number of bytes read. Returns -1 if the 105 * end of the message has been reached. 106 * @throws IOException If an error occurs in reading the underlying 107 * stream. 108 */ 109 @Override 110 public int read(final byte[] buffer) throws IOException 111 { 112 return read(buffer, 0, buffer.length); 113 } 114 115 116 /** 117 * Reads the next number of bytes from the stream into an array and returns 118 * the number of bytes read. Returns -1 if the end of the 119 * message has been reached. The characters are stored in the array 120 * starting from the given offset and up to the length specified. 121 * 122 * @param buffer The byte array in which to store the data. 123 * @param offset The offset into the array at which to start storing data. 124 * @param length The number of bytes to read. 125 * @return The number of bytes read. Returns -1 if the 126 * end of the stream has been reached. 127 * @throws IOException If an error occurs while reading the underlying 128 * stream. 129 */ 130 @Override 131 public int read(final byte[] buffer, int offset, int length) throws IOException 132 { 133 int ch; 134 final int off; 135 136 if (length < 1) { 137 return 0; 138 } 139 140 ch = available(); 141 142 if (length > ch) { 143 length = ch; 144 } 145 146 // If nothing is available, block to read only one character 147 if (length < 1) { 148 length = 1; 149 } 150 151 if ((ch = read()) == -1) { 152 return -1; 153 } 154 155 off = offset; 156 157 do 158 { 159 buffer[offset++] = (byte)ch; 160 } 161 while (--length > 0 && (ch = read()) != -1); 162 163 return offset - off; 164 } 165 166 /** Returns false. Mark is not supported. */ 167 @Override 168 public boolean markSupported() 169 { 170 return false; 171 } 172 173 @Override 174 public int available() throws IOException 175 { 176 final int result; 177 178 result = in.available(); 179 180 if (status == LAST_WAS_NL) { 181 return result + 1; 182 } 183 184 return result; 185 } 186}