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(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 * @exception IOException If an error occurs while reading the underlying 062 * stream. 063 ***/ 064 @Override 065 public int read() throws IOException 066 { 067 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 * @exception IOException If an error occurs in reading the underlying 107 * stream. 108 ***/ 109 @Override 110 public int read(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 * @exception IOException If an error occurs while reading the underlying 128 * stream. 129 ***/ 130 @Override 131 public int read(byte buffer[], int offset, int length) throws IOException 132 { 133 int ch, off; 134 135 if (length < 1) { 136 return 0; 137 } 138 139 ch = available(); 140 141 if (length > ch) { 142 length = ch; 143 } 144 145 // If nothing is available, block to read only one character 146 if (length < 1) { 147 length = 1; 148 } 149 150 if ((ch = read()) == -1) { 151 return -1; 152 } 153 154 off = offset; 155 156 do 157 { 158 buffer[offset++] = (byte)ch; 159 } 160 while (--length > 0 && (ch = read()) != -1); 161 162 return (offset - off); 163 } 164 165 /*** Returns false. Mark is not supported. ***/ 166 @Override 167 public boolean markSupported() 168 { 169 return false; 170 } 171 172 @Override 173 public int available() throws IOException 174 { 175 int result; 176 177 result = in.available(); 178 179 if (__status == __LAST_WAS_NL) { 180 return (result + 1); 181 } 182 183 return result; 184 } 185}