mirror of https://github.com/moparisthebest/k-9
184 lines
6.6 KiB
Java
184 lines
6.6 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.fsck.k9.mail.filter;
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import java.io.FilterOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* Provides Base64 encoding and decoding in a streaming fashion (unlimited size).
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* When encoding the default lineLength is 76 characters and the default
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* lineEnding is CRLF, but these can be overridden by using the appropriate
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* constructor.
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* <p>
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* The default behaviour of the Base64OutputStream is to ENCODE, whereas the
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* default behaviour of the Base64InputStream is to DECODE. But this behaviour
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* can be overridden by using a different constructor.
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* </p><p>
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* This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
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* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
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* </p>
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*
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* @author Apache Software Foundation
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* @version $Id $
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* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
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* @since 1.0-dev
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*/
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public class Base64OutputStream extends FilterOutputStream {
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private final boolean doEncode;
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private final Base64 base64;
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private final byte[] singleByte = new byte[1];
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/**
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* Creates a Base64OutputStream such that all data written is Base64-encoded
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* to the original provided OutputStream.
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*
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* @param out OutputStream to wrap.
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*/
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public Base64OutputStream(OutputStream out) {
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this(out, true);
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}
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/**
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* Creates a Base64OutputStream such that all data written is either
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* Base64-encoded or Base64-decoded to the original provided OutputStream.
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*
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* @param out OutputStream to wrap.
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* @param doEncode true if we should encode all data written to us,
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* false if we should decode.
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*/
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public Base64OutputStream(OutputStream out, boolean doEncode) {
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super(out);
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this.doEncode = doEncode;
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this.base64 = new Base64();
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}
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/**
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* Creates a Base64OutputStream such that all data written is either
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* Base64-encoded or Base64-decoded to the original provided OutputStream.
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*
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* @param out OutputStream to wrap.
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* @param doEncode true if we should encode all data written to us,
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* false if we should decode.
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* @param lineLength If doEncode is true, each line of encoded
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* data will contain lineLength characters.
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* If lineLength <=0, the encoded data is not divided into lines.
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* If doEncode is false, lineLength is ignored.
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* @param lineSeparator If doEncode is true, each line of encoded
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* data will be terminated with this byte sequence (e.g. \r\n).
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* If lineLength <= 0, the lineSeparator is not used.
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* If doEncode is false lineSeparator is ignored.
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*/
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public Base64OutputStream(OutputStream out, boolean doEncode, int lineLength, byte[] lineSeparator) {
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super(out);
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this.doEncode = doEncode;
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this.base64 = new Base64(lineLength, lineSeparator);
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}
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/**
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* Writes the specified <code>byte</code> to this output stream.
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*/
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@Override
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public void write(int i) throws IOException {
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singleByte[0] = (byte) i;
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write(singleByte, 0, 1);
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}
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/**
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* Writes <code>len</code> bytes from the specified
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* <code>b</code> array starting at <code>offset</code> to
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* this output stream.
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*
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* @param b source byte array
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* @param offset where to start reading the bytes
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* @param len maximum number of bytes to write
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*
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* @throws IOException if an I/O error occurs.
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* @throws NullPointerException if the byte array parameter is null
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* @throws IndexOutOfBoundsException if offset, len or buffer size are invalid
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*/
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@Override
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public void write(byte b[], int offset, int len) throws IOException {
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if (b == null) {
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throw new NullPointerException();
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} else if (offset < 0 || len < 0 || offset + len < 0) {
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throw new IndexOutOfBoundsException();
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} else if (offset > b.length || offset + len > b.length) {
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throw new IndexOutOfBoundsException();
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} else if (len > 0) {
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if (doEncode) {
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base64.encode(b, offset, len);
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} else {
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base64.decode(b, offset, len);
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}
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flush(false);
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}
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}
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/**
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* Flushes this output stream and forces any buffered output bytes
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* to be written out to the stream. If propogate is true, the wrapped
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* stream will also be flushed.
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*
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* @param propogate boolean flag to indicate whether the wrapped
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* OutputStream should also be flushed.
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* @throws IOException if an I/O error occurs.
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*/
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private void flush(boolean propogate) throws IOException {
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int avail = base64.avail();
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if (avail > 0) {
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byte[] buf = new byte[avail];
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int c = base64.readResults(buf, 0, avail);
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if (c > 0) {
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out.write(buf, 0, c);
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}
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}
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if (propogate) {
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out.flush();
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}
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}
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/**
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* Flushes this output stream and forces any buffered output bytes
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* to be written out to the stream.
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*
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* @throws IOException if an I/O error occurs.
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*/
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@Override
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public void flush() throws IOException {
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flush(true);
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}
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/**
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* Closes this output stream, flushing any remaining bytes that must be encoded. The
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* underlying stream is flushed but not closed.
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*/
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@Override
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public void close() throws IOException {
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// Notify encoder of EOF (-1).
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if (doEncode) {
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base64.encode(singleByte, 0, -1);
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} else {
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base64.decode(singleByte, 0, -1);
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}
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flush();
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}
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}
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