| /**************************************************************** |
| * 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. * |
| ****************************************************************/ |
| |
| /** |
| * Modified to improve efficiency by Android 21-Aug-2009 |
| */ |
| |
| package org.apache.james.mime4j.decoder; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * 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 final InputStream s; |
| private int outCount = 0; |
| private int outIndex = 0; |
| private final int[] outputBuffer = new int[3]; |
| private final byte[] inputBuffer = new byte[4]; |
| private boolean done = false; |
| |
| public Base64InputStream(InputStream s) { |
| this.s = s; |
| } |
| |
| /** |
| * Closes the underlying stream. |
| * |
| * @throws IOException on I/O errors. |
| */ |
| @Override |
| public void close() throws IOException { |
| s.close(); |
| } |
| |
| @Override |
| public int read() throws IOException { |
| if (outIndex == outCount) { |
| fillBuffer(); |
| if (outIndex == outCount) { |
| return -1; |
| } |
| } |
| |
| return outputBuffer[outIndex++]; |
| } |
| |
| /** |
| * Retrieve data from the underlying stream, decode it, |
| * and put the results in the byteq. |
| * @throws IOException |
| */ |
| private void fillBuffer() throws IOException { |
| outCount = 0; |
| outIndex = 0; |
| int inCount = 0; |
| |
| int i; |
| // "done" is needed for the two successive '=' at the end |
| while (!done) { |
| switch (i = s.read()) { |
| case -1: |
| // No more input - just return, let outputBuffer drain out, and be done |
| return; |
| case '=': |
| // once we meet the first '=', avoid reading the second '=' |
| done = true; |
| decodeAndEnqueue(inCount); |
| return; |
| default: |
| byte sX = TRANSLATION[i]; |
| if (sX < 0) continue; |
| inputBuffer[inCount++] = sX; |
| if (inCount == 4) { |
| decodeAndEnqueue(inCount); |
| return; |
| } |
| break; |
| } |
| } |
| } |
| |
| private void decodeAndEnqueue(int len) { |
| int accum = 0; |
| accum |= inputBuffer[0] << 18; |
| accum |= inputBuffer[1] << 12; |
| accum |= inputBuffer[2] << 6; |
| accum |= inputBuffer[3]; |
| |
| // There's a bit of duplicated code here because we want to have straight-through operation |
| // for the most common case of len==4 |
| if (len == 4) { |
| outputBuffer[0] = (accum >> 16) & 0xFF; |
| outputBuffer[1] = (accum >> 8) & 0xFF; |
| outputBuffer[2] = (accum) & 0xFF; |
| outCount = 3; |
| return; |
| } else if (len == 3) { |
| outputBuffer[0] = (accum >> 16) & 0xFF; |
| outputBuffer[1] = (accum >> 8) & 0xFF; |
| outCount = 2; |
| return; |
| } else { // len == 2 |
| outputBuffer[0] = (accum >> 16) & 0xFF; |
| outCount = 1; |
| return; |
| } |
| } |
| |
| 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 */ |
| }; |
| |
| |
| } |