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 slashNSeen;
034
035    private boolean slashRSeen;
036
037    private boolean eofSeen;
038
039    private final InputStream target;
040
041    private final boolean ensureLineFeedAtEndOfFile;
042
043    /**
044     * Creates an input stream that filters another stream
045     *
046     * @param in                        The input stream to wrap
047     * @param ensureLineFeedAtEndOfFile true to ensure that the file ends with LF
048     */
049    public UnixLineEndingInputStream(final InputStream in, final boolean ensureLineFeedAtEndOfFile) {
050        this.target = in;
051        this.ensureLineFeedAtEndOfFile = ensureLineFeedAtEndOfFile;
052    }
053
054    /**
055     * Reads the next item from the target, updating internal flags in the process
056     * @return the next int read from the target stream
057     * @throws IOException upon error
058     */
059    private int readWithUpdate() throws IOException {
060        final int target = this.target.read();
061        eofSeen = target == EOF;
062        if (eofSeen) {
063            return target;
064        }
065        slashNSeen = target == LF;
066        slashRSeen = target == CR;
067        return target;
068    }
069
070    /**
071     * {@inheritDoc}
072     */
073    @Override
074    public int read() throws IOException {
075        final boolean previousWasSlashR = slashRSeen;
076        if (eofSeen) {
077            return eofGame(previousWasSlashR);
078        }
079        final int target = readWithUpdate();
080        if (eofSeen) {
081            return eofGame(previousWasSlashR);
082        }
083        if (slashRSeen) {
084            return LF;
085        }
086
087        if (previousWasSlashR && slashNSeen) {
088            return read();
089        }
090
091        return target;
092    }
093
094    /**
095     * Handles the EOF-handling at the end of the stream
096     * @param previousWasSlashR Indicates if the last seen was a \r
097     * @return The next char to output to the stream
098     */
099    private int eofGame(final boolean previousWasSlashR) {
100        if (previousWasSlashR || !ensureLineFeedAtEndOfFile) {
101            return EOF;
102        }
103        if (!slashNSeen) {
104            slashNSeen = true;
105            return LF;
106        }
107        return EOF;
108    }
109
110    /**
111     * Closes the stream. Also closes the underlying stream.
112     * @throws IOException upon error
113     */
114    @Override
115    public void close() throws IOException {
116        super.close();
117        target.close();
118    }
119
120    /**
121     * {@inheritDoc}
122     */
123    @Override
124    public synchronized void mark(final int readlimit) {
125        throw UnsupportedOperationExceptions.mark();
126    }
127}