    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 * &lt;LF&gt; (linefeed) characters with &lt;CR&gt;&lt;LF&gt; (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     * @throws 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     * @throws 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     * @throws 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}