AutoCRLFOutputStream.java

/*
 * Copyright (C) 2011, 2013 Robin Rosenberg
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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package org.eclipse.jgit.util.io;

import java.io.IOException;
import java.io.OutputStream;

import org.eclipse.jgit.diff.RawText;

/**
 * An OutputStream that expands LF to CRLF.
 *
 * Existing CRLF are not expanded to CRCRLF, but retained as is.
 *
 * A binary check on the first 8000 bytes is performed and in case of binary
 * files, canonicalization is turned off (for the complete file).
 */
public class AutoCRLFOutputStream extends OutputStream {

    static final int BUFFER_SIZE = 8000;

    private final OutputStream out;

    private int buf = -1;

    private byte[] binbuf = new byte[BUFFER_SIZE];

    private byte[] onebytebuf = new byte[1];

    private int binbufcnt = 0;

    private boolean detectBinary;

    private boolean isBinary;

    /**
     * <p>Constructor for AutoCRLFOutputStream.</p>
     *
     * @param out a {@link java.io.OutputStream} object.
     */
    public AutoCRLFOutputStream(OutputStream out) {
        this(out, true);
    }

    /**
     * <p>Constructor for AutoCRLFOutputStream.</p>
     *
     * @param out a {@link java.io.OutputStream} object.
     * @param detectBinary
     *            whether binaries should be detected
     * @since 4.3
     */
    public AutoCRLFOutputStream(OutputStream out, boolean detectBinary) {
        this.out = out;
        this.detectBinary = detectBinary;
    }

    /** {@inheritDoc} */
    @Override
    public void write(int b) throws IOException {
        onebytebuf[0] = (byte) b;
        write(onebytebuf, 0, 1);
    }

    /** {@inheritDoc} */
    @Override
    public void write(byte[] b) throws IOException {
        int overflow = buffer(b, 0, b.length);
        if (overflow > 0)
            write(b, b.length - overflow, overflow);
    }

    /** {@inheritDoc} */
    @Override
    public void write(byte[] b, int startOff, int startLen)
            throws IOException {
        final int overflow = buffer(b, startOff, startLen);
        if (overflow < 0)
            return;
        final int off = startOff + startLen - overflow;
        final int len = overflow;
        if (len == 0)
            return;
        int lastw = off;
        if (isBinary) {
            out.write(b, off, len);
            return;
        }
        for (int i = off; i < off + len; ++i) {
            final byte c = b[i];
            if (c == '\r') {
                buf = '\r';
            } else if (c == '\n') {
                if (buf != '\r') {
                    if (lastw < i) {
                        out.write(b, lastw, i - lastw);
                    }
                    out.write('\r');
                    lastw = i;
                }
                buf = -1;
            } else {
                buf = -1;
            }
        }
        if (lastw < off + len) {
            out.write(b, lastw, off + len - lastw);
        }
        if (b[off + len - 1] == '\r')
            buf = '\r';
    }

    private int buffer(byte[] b, int off, int len) throws IOException {
        if (binbufcnt > binbuf.length)
            return len;
        int copy = Math.min(binbuf.length - binbufcnt, len);
        System.arraycopy(b, off, binbuf, binbufcnt, copy);
        binbufcnt += copy;
        int remaining = len - copy;
        if (remaining > 0)
            decideMode();
        return remaining;
    }

    private void decideMode() throws IOException {
        if (detectBinary) {
            isBinary = RawText.isBinary(binbuf, binbufcnt);
            detectBinary = false;
        }
        int cachedLen = binbufcnt;
        binbufcnt = binbuf.length + 1; // full!
        write(binbuf, 0, cachedLen);
    }

    /** {@inheritDoc} */
    @Override
    public void flush() throws IOException {
        if (binbufcnt <= binbuf.length)
            decideMode();
        buf = -1;
        out.flush();
    }

    /** {@inheritDoc} */
    @Override
    public void close() throws IOException {
        flush();
        out.close();
    }
}