/**************************************************************** | |
* Licensed to the Apache Software Foundation (ASF) under one * | |
* or more contributor license agreements. See the NOTICE file * | |
* distributed with this work for additional information * | |
* regarding copyright ownership. The ASF licenses this file * | |
* to you 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.james.mime4j.decoder; | |
import java.io.IOException; | |
import java.io.InputStream; | |
import org.apache.commons.logging.Log; | |
import org.apache.commons.logging.LogFactory; | |
/** | |
* Performs Base-64 decoding on an underlying stream. | |
* | |
* | |
* @version $Id: Base64InputStream.java,v 1.3 2004/11/29 13:15:47 ntherning Exp $ | |
*/ | |
public class Base64InputStream extends InputStream { | |
private static Log log = LogFactory.getLog(Base64InputStream.class); | |
private final InputStream s; | |
private final ByteQueue byteq = new ByteQueue(3); | |
private boolean done = false; | |
public Base64InputStream(InputStream s) { | |
this.s = s; | |
} | |
/** | |
* Closes the underlying stream. | |
* | |
* @throws IOException on I/O errors. | |
*/ | |
public void close() throws IOException { | |
s.close(); | |
} | |
public int read() throws IOException { | |
if (byteq.count() == 0) { | |
fillBuffer(); | |
if (byteq.count() == 0) { | |
return -1; | |
} | |
} | |
byte val = byteq.dequeue(); | |
if (val >= 0) | |
return val; | |
else | |
return val & 0xFF; | |
} | |
/** | |
* Retrieve data from the underlying stream, decode it, | |
* and put the results in the byteq. | |
* @throws IOException | |
*/ | |
private void fillBuffer() throws IOException { | |
byte[] data = new byte[4]; | |
int pos = 0; | |
int i; | |
while (!done) { | |
switch (i = s.read()) { | |
case -1: | |
if (pos > 0) { | |
log.warn("Unexpected EOF in MIME parser, dropping " | |
+ pos + " sextets"); | |
} | |
return; | |
case '=': | |
decodeAndEnqueue(data, pos); | |
done = true; | |
break; | |
default: | |
byte sX = TRANSLATION[i]; | |
if (sX < 0) | |
continue; | |
data[pos++] = sX; | |
if (pos == data.length) { | |
decodeAndEnqueue(data, pos); | |
return; | |
} | |
break; | |
} | |
} | |
} | |
private void decodeAndEnqueue(byte[] data, int len) { | |
int accum = 0; | |
accum |= data[0] << 18; | |
accum |= data[1] << 12; | |
accum |= data[2] << 6; | |
accum |= data[3]; | |
byte b1 = (byte)(accum >>> 16); | |
byteq.enqueue(b1); | |
if (len > 2) { | |
byte b2 = (byte)((accum >>> 8) & 0xFF); | |
byteq.enqueue(b2); | |
if (len > 3) { | |
byte b3 = (byte)(accum & 0xFF); | |
byteq.enqueue(b3); | |
} | |
} | |
} | |
private static byte[] TRANSLATION = { | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x00 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x10 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 0x20 */ | |
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 0x30 */ | |
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 */ | |
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 0x50 */ | |
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 */ | |
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x80 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x90 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0xA0 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0xB0 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0xC0 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0xD0 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0xE0 */ | |
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 /* 0xF0 */ | |
}; | |
} |