    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 Windows line endings, CRLF.
    028 *
    029 * @since 2.5
    030 */
    031public class WindowsLineEndingInputStream extends AbstractLineEndingInputStream {
    032
    033    private boolean injectSlashLf;
    034
    035    /**
    036     * Constructs an input stream that filters another stream.
    037     *
    038     * @param in                        The input stream to wrap.
    039     * @param lineFeedAtEos true to ensure that the stream ends with CRLF.
    040     */
    041    public WindowsLineEndingInputStream(final InputStream in, final boolean lineFeedAtEos) {
    042        super(in, lineFeedAtEos);
    043    }
    044
    045    /**
    046     * Handles the end of stream condition.
    047     *
    048     * @return The next char to output to the stream.
    049     */
    050    private int handleEos() {
    051        if (!lineFeedAtEos) {
    052            return EOF;
    053        }
    054        if (!atSlashLf && !atSlashCr) {
    055            atSlashCr = true;
    056            return CR;
    057        }
    058        if (!atSlashLf) {
    059            atSlashCr = false;
    060            atSlashLf = true;
    061            return LF;
    062        }
    063        return EOF;
    064    }
    065
    066    /**
    067     * {@inheritDoc}
    068     */
    069    @Override
    070    public synchronized int read() throws IOException {
    071        if (atEos) {
    072            return handleEos();
    073        }
    074        if (injectSlashLf) {
    075            injectSlashLf = false;
    076            return LF;
    077        }
    078        final boolean prevWasSlashR = atSlashCr;
    079        final int target = in.read();
    080        atEos = target == EOF;
    081        if (!atEos) {
    082            atSlashCr = target == CR;
    083            atSlashLf = target == LF;
    084        }
    085        if (atEos) {
    086            return handleEos();
    087        }
    088        if (target == LF && !prevWasSlashR) {
    089            injectSlashLf = true;
    090            return CR;
    091        }
    092        return target;
    093    }
    094}