    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
    018    package org.apache.commons.net.io;
    019
    020    import java.io.FilterInputStream;
    021    import java.io.IOException;
    022    import 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     * <p>
    032     * <p>
    033     ***/
    034
    035    public 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         * <p>
    046         * @param input  The InputStream to .
    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         * <p>
    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         * <p>
    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         * <p>
    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    }