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/**
*
* Copyright 2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.geronimo.javamail.util;
import java.io.IOException;
import java.io.OutputStream;
/**
* An implementation of an OutputStream that performs MIME linebreak
* canonicalization and "byte-stuff" so that data content does not get mistaken
* for a message data-end marker (CRLF.CRLF)l
*
* @version $Rev$ $Date$
*/
public class MIMEOutputStream extends OutputStream {
// the wrappered output stream.
protected OutputStream out;
// last character we handled...used to recongnize line breaks.
protected int lastWrite = -1;
// a flag to indicate we've just processed a line break. This is used for
// byte stuffing purposes. This
// is initially true, because if the first character of the content is a
// period, we need to byte-stuff
// immediately.
protected boolean atLineBreak = true;
/**
* Create an output stream that writes to the target output stream.
*
* @param out
* The wrapped output stream.
*/
public MIMEOutputStream(OutputStream out) {
this.out = out;
}
// in order for this to work, we only need override the single character
// form, as the others
// funnel through this one by default.
public void write(int ch) throws IOException {
// if this is a CR character, always write out a full sequence, and
// remember that we just did this.
if (ch == '\r') {
out.write((byte) '\r');
out.write((byte) '\n');
// we've just taken a break;
atLineBreak = true;
}
// if this is a new line, then we need to determine if this is a loner
// or part of a CRLF sequence.
else if (ch == '\n') {
// is this a lone ranger?
if (lastWrite != '\r') {
// write the full CRLF sequence.
out.write((byte) '\r');
out.write((byte) '\n');
}
// regardless of whether we wrote something or not, we're still at a
// line break.
atLineBreak = true;
}
// potential byte-stuffing situation?
else if (ch == '.') {
// ok, this is a potential stuff situation. Did we just have a line
// break? Double up the character.
if (atLineBreak) {
out.write('.');
}
out.write('.');
atLineBreak = false;
} else {
// just write this out and flip the linebreak flag.
out.write(ch);
atLineBreak = false;
}
// remember this last one for CRLF tracking purposes.
lastWrite = ch;
}
}