    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 *      https://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 AbstractLineEndingInputStream {
    032
    033    /**
    034     * Constructs an input stream that filters another stream
    035     *
    036     * @param inputStream                        The input stream to wrap.
    037     * @param lineFeedAtEos true to ensure that the file ends with LF.
    038     */
    039    public UnixLineEndingInputStream(final InputStream inputStream, final boolean lineFeedAtEos) {
    040        super(inputStream, lineFeedAtEos);
    041    }
    042
    043    /**
    044     * Handles the end of stream condition.
    045     *
    046     * @param previousWasSlashCr Indicates if the last seen was a {@code \r}.
    047     * @return The next char to output to the stream.
    048     */
    049    private int handleEos(final boolean previousWasSlashCr) {
    050        if (previousWasSlashCr || !lineFeedAtEos) {
    051            return EOF;
    052        }
    053        if (!atSlashLf) {
    054            atSlashLf = true;
    055            return LF;
    056        }
    057        return EOF;
    058    }
    059
    060    /**
    061     * {@inheritDoc}
    062     */
    063    @Override
    064    public synchronized int read() throws IOException {
    065        final boolean previousWasSlashR = atSlashCr;
    066        if (atEos) {
    067            return handleEos(previousWasSlashR);
    068        }
    069        final int target = readUpdate();
    070        if (atEos) {
    071            return handleEos(previousWasSlashR);
    072        }
    073        if (atSlashCr) {
    074            return LF;
    075        }
    076
    077        if (previousWasSlashR && atSlashLf) {
    078            return read();
    079        }
    080
    081        return target;
    082    }
    083
    084    /**
    085     * Reads the next item from the target, updating internal flags in the process
    086     *
    087     * @return the next int read from the target stream.
    088     * @throws IOException If an I/O error occurs.
    089     */
    090    private int readUpdate() throws IOException {
    091        final int target = this.in.read();
    092        atEos = target == EOF;
    093        if (atEos) {
    094            return target;
    095        }
    096        atSlashCr = target == CR;
    097        atSlashLf = target == LF;
    098        return target;
    099    }
    100}