    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.io.input;
    018
    019import static org.apache.commons.io.IOUtils.CR;
    020import static org.apache.commons.io.IOUtils.EOF;
    021import static org.apache.commons.io.IOUtils.LF;
    022
    023import java.io.IOException;
    024import java.io.InputStream;
    025
    026/**
    027 * A filtering input stream that ensures the content will have UNIX-style line endings, LF.
    028 *
    029 * @since 2.5
    030 */
    031public class UnixLineEndingInputStream extends InputStream {
    032
    033    private boolean atEos;
    034
    035    private boolean atSlashCr;
    036
    037    private boolean atSlashLf;
    038
    039    private final InputStream in;
    040
    041    private final boolean lineFeedAtEndOfFile;
    042
    043    /**
    044     * Creates an input stream that filters another stream
    045     *
    046     * @param inputStream                        The input stream to wrap
    047     * @param ensureLineFeedAtEndOfFile true to ensure that the file ends with LF
    048     */
    049    public UnixLineEndingInputStream(final InputStream inputStream, final boolean ensureLineFeedAtEndOfFile) {
    050        this.in = inputStream;
    051        this.lineFeedAtEndOfFile = ensureLineFeedAtEndOfFile;
    052    }
    053
    054    /**
    055     * Closes the stream. Also closes the underlying stream.
    056     * @throws IOException upon error
    057     */
    058    @Override
    059    public void close() throws IOException {
    060        super.close();
    061        in.close();
    062    }
    063
    064    /**
    065     * Handles the end of stream condition.
    066     *
    067     * @param previousWasSlashCr Indicates if the last seen was a {@code \r}.
    068     * @return The next char to output to the stream.
    069     */
    070    private int handleEos(final boolean previousWasSlashCr) {
    071        if (previousWasSlashCr || !lineFeedAtEndOfFile) {
    072            return EOF;
    073        }
    074        if (!atSlashLf) {
    075            atSlashLf = true;
    076            return LF;
    077        }
    078        return EOF;
    079    }
    080
    081    /**
    082     * {@inheritDoc}
    083     */
    084    @Override
    085    public synchronized void mark(final int readlimit) {
    086        throw UnsupportedOperationExceptions.mark();
    087    }
    088
    089    /**
    090     * {@inheritDoc}
    091     */
    092    @Override
    093    public int read() throws IOException {
    094        final boolean previousWasSlashR = atSlashCr;
    095        if (atEos) {
    096            return handleEos(previousWasSlashR);
    097        }
    098        final int target = readWithUpdate();
    099        if (atEos) {
    100            return handleEos(previousWasSlashR);
    101        }
    102        if (atSlashCr) {
    103            return LF;
    104        }
    105
    106        if (previousWasSlashR && atSlashLf) {
    107            return read();
    108        }
    109
    110        return target;
    111    }
    112
    113    /**
    114     * Reads the next item from the target, updating internal flags in the process
    115     * @return the next int read from the target stream
    116     * @throws IOException upon error
    117     */
    118    private int readWithUpdate() throws IOException {
    119        final int target = this.in.read();
    120        atEos = target == EOF;
    121        if (atEos) {
    122            return target;
    123        }
    124        atSlashCr = target == CR;
    125        atSlashLf = target == LF;
    126        return target;
    127    }
    128}