706 lines
26 KiB
Java
706 lines
26 KiB
Java
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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.android.common;
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/**
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* Utilities for encoding and decoding the Base64 encoding. See RFCs
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* 2045 and 3548.
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*/
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public class Base64 {
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/**
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* Default values for encoder/decoder flags.
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*/
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public static final int DEFAULT = 0;
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/**
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* Encoder flag bit to indicate you want the padding '='
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* characters at the end (if any) to be omitted.
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*/
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public static final int NO_PADDING = 1;
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/**
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* Encoder flag bit to indicate you want all line terminators to
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* be omitted (ie, the output will be on one long line).
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*/
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public static final int NO_WRAP = 2;
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/**
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* Encoder flag bit to indicate you want lines to be ended with
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* CRLF instead of just LF.
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*/
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public static final int CRLF = 4;
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/**
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* Encoder/decoder flag bit to indicate using the "web safe"
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* variant of Base64 (see RFC 3548 section 4) where '-' and '_'
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* are used in place of '+' and '/'.
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*/
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public static final int WEB_SAFE = 8;
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/**
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* Flag to pass to Base64OutputStream to indicate that it should
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* not close the output stream it is wrapping when it itself is
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* closed.
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*/
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public static final int NO_CLOSE = 16;
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// --------------------------------------------------------
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// decoding
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// --------------------------------------------------------
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/**
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* Lookup table for turning bytes into their position in the
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* Base64 alphabet.
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*/
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private static final int DECODE[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
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-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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};
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/**
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* Decode lookup table for the "web safe" variant (RFC 3548
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* sec. 4) where - and _ replace + and /.
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*/
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private static final int DECODE_WEBSAFE[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,
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-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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};
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/** Non-data values in the DECODE arrays. */
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private static final int SKIP = -1;
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private static final int EQUALS = -2;
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/**
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* Decode the Base64-encoded data in input and return the data in
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* a new byte array.
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*
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* The padding '=' characters at the end are considered optional, but
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* if any are present, there must be the correct number of them.
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*
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* @param input the input String to decode, which is converted to
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* bytes using the default charset
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* @param flags controls certain features of the decoded output.
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* Pass {@code DEFAULT} to decode standard Base64.
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*
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* @throws IllegalArgumentException if the input contains
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* incorrect padding
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*/
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public static byte[] decode(String str, int flags) {
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return decode(str.getBytes(), flags);
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}
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/**
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* Decode the Base64-encoded data in input and return the data in
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* a new byte array.
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*
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* The padding '=' characters at the end are considered optional, but
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* if any are present, there must be the correct number of them.
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*
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* @param input the input array to decode
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* @param flags controls certain features of the decoded output.
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* Pass {@code DEFAULT} to decode standard Base64.
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*
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* @throws IllegalArgumentException if the input contains
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* incorrect padding
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*/
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public static byte[] decode(byte[] input, int flags) {
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return decode(input, 0, input.length, flags);
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}
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/**
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* Decode the Base64-encoded data in input and return the data in
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* a new byte array.
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*
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* The padding '=' characters at the end are considered optional, but
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* if any are present, there must be the correct number of them.
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*
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* @param input the data to decode
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* @param offset the position within the input array at which to start
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* @param len the number of bytes of input to decode
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* @param flags controls certain features of the decoded output.
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* Pass {@code DEFAULT} to decode standard Base64.
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*
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* @throws IllegalArgumentException if the input contains
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* incorrect padding
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*/
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public static byte[] decode(byte[] input, int offset, int len, int flags) {
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// Allocate space for the most data the input could represent.
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// (It could contain less if it contains whitespace, etc.)
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DecoderState state = new DecoderState(flags, new byte[len*3/4]);
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if (!decodeInternal(input, offset, len, state, true)) {
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throw new IllegalArgumentException("bad base-64");
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}
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// Maybe we got lucky and allocated exactly enough output space.
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if (state.op == state.output.length) {
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return state.output;
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}
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// Need to shorten the array, so allocate a new one of the
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// right size and copy.
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byte[] temp = new byte[state.op];
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System.arraycopy(state.output, 0, temp, 0, state.op);
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return temp;
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}
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/* package */ static class DecoderState {
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public byte[] output;
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public int op;
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public int state; // state number (0 to 6)
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public int value;
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final public int[] alphabet;
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public DecoderState(int flags, byte[] output) {
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this.output = output;
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alphabet = ((flags & WEB_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;
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state = 0;
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value = 0;
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}
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}
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/**
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* Decode another block of input data.
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*
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* @param dstate a DecoderState object whose (caller-provided)
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* output array is big enough to hold all the decoded data.
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* On return, dstate.op will be set to the length of the
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* decoded data.
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* @param finish true if this is the final call to decodeInternal
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* with the given DecoderState object. Will finalize the
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* decoder state and include any final bytes in the output.
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*
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* @return true if the state machine is still healthy. false if
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* bad base-64 data has been detected in the input stream.
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*/
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/* package */ static boolean decodeInternal(
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byte[] input, int offset, int len, final DecoderState dstate, boolean finish) {
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if (dstate.state == 6) return false;
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int state = dstate.state;
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int value = dstate.value;
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final int[] decode = dstate.alphabet;
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final byte[] output = dstate.output;
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int op = 0;
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int p = offset;
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len += offset;
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while (p < len) {
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// Try the fast path: we're starting a new tuple and the
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// next four bytes of the input stream are all data
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// bytes. This corresponds to going through states
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// 0-1-2-3-0. We expect to use this method for most of
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// the data.
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//
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// If any of the next four bytes of input are non-data
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// (whitespace, etc.), value will end up negative. (All
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// the non-data values in decode are small negative
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// numbers, so shifting any of them up and or'ing them
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// together will result in a value with its top bit set.)
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//
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// You can remove this whole block and the output should
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// be the same, just slower.
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if (state == 0 && p+4 <= len &&
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(value = ((decode[input[p] & 0xff] << 18) |
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(decode[input[p+1] & 0xff] << 12) |
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(decode[input[p+2] & 0xff] << 6) |
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(decode[input[p+3] & 0xff]))) >= 0) {
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output[op+2] = (byte) value;
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output[op+1] = (byte) (value >> 8);
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output[op] = (byte) (value >> 16);
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op += 3;
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p += 4;
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continue;
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}
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// The fast path isn't available -- either we've read a
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// partial tuple, or the next four input bytes aren't all
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// data, or whatever. Fall back to the slower state
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// machine implementation.
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//
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// States 0-3 are reading through the next input tuple.
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// State 4 is having read one '=' and expecting exactly
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// one more.
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// State 5 is expecting no more data or padding characters
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// in the input.
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// State 6 is the error state; an error has been detected
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// in the input and no future input can "fix" it.
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int d = decode[input[p++] & 0xff];
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switch (state) {
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case 0:
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if (d >= 0) {
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value = d;
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++state;
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} else if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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case 1:
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if (d >= 0) {
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value = (value << 6) | d;
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++state;
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} else if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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case 2:
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if (d >= 0) {
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value = (value << 6) | d;
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++state;
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} else if (d == EQUALS) {
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// Emit the last (partial) output tuple;
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// expect exactly one more padding character.
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output[op++] = (byte) (value >> 4);
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state = 4;
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} else if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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case 3:
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if (d >= 0) {
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// Emit the output triple and return to state 0.
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value = (value << 6) | d;
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output[op+2] = (byte) value;
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output[op+1] = (byte) (value >> 8);
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output[op] = (byte) (value >> 16);
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op += 3;
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state = 0;
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} else if (d == EQUALS) {
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// Emit the last (partial) output tuple;
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// expect no further data or padding characters.
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output[op+1] = (byte) (value >> 2);
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output[op] = (byte) (value >> 10);
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op += 2;
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state = 5;
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} else if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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case 4:
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if (d == EQUALS) {
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++state;
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} else if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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case 5:
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if (d != SKIP) {
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dstate.state = 6;
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return false;
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}
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break;
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}
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}
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if (!finish) {
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// We're out of input, but a future call could provide
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// more. Return the output we've produced on this call
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// and save the current state of the state machine.
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dstate.state = state;
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dstate.value = value;
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dstate.op = op;
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return true;
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}
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// Done reading input. Now figure out where we are left in
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// the state machine and finish up.
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switch (state) {
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case 0:
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// Output length is a multiple of three. Fine.
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break;
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case 1:
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// Read one extra input byte, which isn't enough to
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// make another output byte. Illegal.
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dstate.state = 6;
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return false;
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case 2:
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// Read two extra input bytes, enough to emit 1 more
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// output byte. Fine.
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output[op++] = (byte) (value >> 4);
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break;
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case 3:
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// Read three extra input bytes, enough to emit 2 more
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// output bytes. Fine.
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output[op+1] = (byte) (value >> 2);
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output[op] = (byte) (value >> 10);
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op += 2;
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break;
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case 4:
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// Read one padding '=' when we expected 2. Illegal.
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dstate.state = 6;
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return false;
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case 5:
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// Read all the padding '='s we expected and no more.
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// Fine.
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break;
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}
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dstate.op = op;
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return true;
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}
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// --------------------------------------------------------
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// encoding
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// --------------------------------------------------------
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/**
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* Emit a new line every this many output tuples. Corresponds to
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* a 76-character line length (the maximum allowable according to
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* RFC 2045).
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*/
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private static final int LINE_GROUPS = 19;
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/**
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* Lookup table for turning Base64 alphabet positions (6 bits)
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* into output bytes.
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*/
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private static final byte ENCODE[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/',
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};
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/**
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* Lookup table for turning Base64 alphabet positions (6 bits)
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* into output bytes.
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*/
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private static final byte ENCODE_WEBSAFE[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '-', '_',
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};
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/**
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* Base64-encode the given data and return a newly allocated
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* String with the result.
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*
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* @param input the data to encode
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* @param flags controls certain features of the encoded output.
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* Passing {@code DEFAULT} results in output that
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* adheres to RFC 2045.
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*/
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public static String encodeToString(byte[] input, int flags) {
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return new String(encode(input, flags));
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}
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/**
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* Base64-encode the given data and return a newly allocated
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* String with the result.
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*
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* @param input the data to encode
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* @param offset the position within the input array at which to
|
|
* start
|
|
* @param len the number of bytes of input to encode
|
|
* @param flags controls certain features of the encoded output.
|
|
* Passing {@code DEFAULT} results in output that
|
|
* adheres to RFC 2045.
|
|
*/
|
|
public static String encodeToString(byte[] input, int offset, int len, int flags) {
|
|
return new String(encode(input, offset, len, flags));
|
|
}
|
|
|
|
/**
|
|
* Base64-encode the given data and return a newly allocated
|
|
* byte[] with the result.
|
|
*
|
|
* @param input the data to encode
|
|
* @param flags controls certain features of the encoded output.
|
|
* Passing {@code DEFAULT} results in output that
|
|
* adheres to RFC 2045.
|
|
*/
|
|
public static byte[] encode(byte[] input, int flags) {
|
|
return encode(input, 0, input.length, flags);
|
|
}
|
|
|
|
/**
|
|
* Base64-encode the given data and return a newly allocated
|
|
* byte[] with the result.
|
|
*
|
|
* @param input the data to encode
|
|
* @param offset the position within the input array at which to
|
|
* start
|
|
* @param len the number of bytes of input to encode
|
|
* @param flags controls certain features of the encoded output.
|
|
* Passing {@code DEFAULT} results in output that
|
|
* adheres to RFC 2045.
|
|
*/
|
|
public static byte[] encode(byte[] input, int offset, int len, int flags) {
|
|
EncoderState state = new EncoderState(flags, null);
|
|
|
|
// Compute the exact length of the array we will produce.
|
|
int output_len = len / 3 * 4;
|
|
|
|
// Account for the tail of the data and the padding bytes, if any.
|
|
if (state.do_padding) {
|
|
if (len % 3 > 0) {
|
|
output_len += 4;
|
|
}
|
|
} else {
|
|
switch (len % 3) {
|
|
case 0: break;
|
|
case 1: output_len += 2; break;
|
|
case 2: output_len += 3; break;
|
|
}
|
|
}
|
|
|
|
// Account for the newlines, if any.
|
|
if (state.do_newline && len > 0) {
|
|
output_len += (((len-1) / (3 * LINE_GROUPS)) + 1) * (state.do_cr ? 2 : 1);
|
|
}
|
|
|
|
state.output = new byte[output_len];
|
|
encodeInternal(input, offset, len, state, true);
|
|
|
|
assert state.op == output_len;
|
|
|
|
return state.output;
|
|
}
|
|
|
|
/* package */ static class EncoderState {
|
|
public byte[] output;
|
|
public int op;
|
|
|
|
final public byte[] tail;
|
|
public int tailLen;
|
|
public int count;
|
|
|
|
final public boolean do_padding;
|
|
final public boolean do_newline;
|
|
final public boolean do_cr;
|
|
final public byte[] alphabet;
|
|
|
|
public EncoderState(int flags, byte[] output) {
|
|
this.output = output;
|
|
|
|
do_padding = (flags & NO_PADDING) == 0;
|
|
do_newline = (flags & NO_WRAP) == 0;
|
|
do_cr = (flags & CRLF) != 0;
|
|
alphabet = ((flags & WEB_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;
|
|
|
|
tail = new byte[2];
|
|
tailLen = 0;
|
|
|
|
count = do_newline ? LINE_GROUPS : -1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Encode another block of input data.
|
|
*
|
|
* @param estate an EncoderState object whose (caller-provided)
|
|
* output array is big enough to hold all the encoded data.
|
|
* On return, estate.op will be set to the length of the
|
|
* encoded data.
|
|
* @param finish true if this is the final call to encodeInternal
|
|
* with the given EncoderState object. Will finalize the
|
|
* encoder state and include any final bytes in the output.
|
|
*/
|
|
static void encodeInternal(byte[] input, int offset, int len,
|
|
final EncoderState estate, boolean finish) {
|
|
final boolean do_cr = estate.do_cr;
|
|
final boolean do_newline = estate.do_newline;
|
|
final boolean do_padding = estate.do_padding;
|
|
final byte[] output = estate.output;
|
|
|
|
int op = 0;
|
|
|
|
int p = offset;
|
|
len += offset;
|
|
int v = -1;
|
|
int count = estate.count;
|
|
|
|
// First we need to concatenate the tail of the previous call
|
|
// with any input bytes available now and see if we can empty
|
|
// the tail.
|
|
|
|
switch (estate.tailLen) {
|
|
case 0:
|
|
// There was no tail.
|
|
break;
|
|
|
|
case 1:
|
|
if (p+2 <= len) {
|
|
// A 1-byte tail with at least 2 bytes of
|
|
// input available now.
|
|
v = ((estate.tail[0] & 0xff) << 16) |
|
|
((input[p++] & 0xff) << 8) |
|
|
(input[p++] & 0xff);
|
|
estate.tailLen = 0;
|
|
};
|
|
break;
|
|
|
|
case 2:
|
|
if (p+1 <= len) {
|
|
// A 2-byte tail with at least 1 byte of input.
|
|
v = ((estate.tail[0] & 0xff) << 16) |
|
|
((estate.tail[1] & 0xff) << 8) |
|
|
(input[p++] & 0xff);
|
|
estate.tailLen = 0;
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (v != -1) {
|
|
output[op++] = estate.alphabet[(v >> 18) & 0x3f];
|
|
output[op++] = estate.alphabet[(v >> 12) & 0x3f];
|
|
output[op++] = estate.alphabet[(v >> 6) & 0x3f];
|
|
output[op++] = estate.alphabet[v & 0x3f];
|
|
if (--count == 0) {
|
|
if (do_cr) output[op++] = '\r';
|
|
output[op++] = '\n';
|
|
count = LINE_GROUPS;
|
|
}
|
|
}
|
|
|
|
// At this point either there is no tail, or there are fewer
|
|
// than 3 bytes of input available.
|
|
|
|
// The main loop, turning 3 input bytes into 4 output bytes on
|
|
// each iteration.
|
|
while (p+3 <= len) {
|
|
v = ((input[p++] & 0xff) << 16) |
|
|
((input[p++] & 0xff) << 8) |
|
|
(input[p++] & 0xff);
|
|
output[op++] = estate.alphabet[(v >> 18) & 0x3f];
|
|
output[op++] = estate.alphabet[(v >> 12) & 0x3f];
|
|
output[op++] = estate.alphabet[(v >> 6) & 0x3f];
|
|
output[op++] = estate.alphabet[v & 0x3f];
|
|
if (--count == 0) {
|
|
if (do_cr) output[op++] = '\r';
|
|
output[op++] = '\n';
|
|
count = LINE_GROUPS;
|
|
}
|
|
}
|
|
|
|
if (finish) {
|
|
// Finish up the tail of the input. Note that we need to
|
|
// consume any bytes in estate.tail before any bytes
|
|
// remaining in input; there should be at most two bytes
|
|
// total.
|
|
|
|
if (p-estate.tailLen == len-1) {
|
|
int t = 0;
|
|
v = ((estate.tailLen > 0 ? estate.tail[t++] : input[p++]) & 0xff) << 4;
|
|
estate.tailLen -= t;
|
|
output[op++] = estate.alphabet[(v >> 6) & 0x3f];
|
|
output[op++] = estate.alphabet[v & 0x3f];
|
|
if (do_padding) {
|
|
output[op++] = '=';
|
|
output[op++] = '=';
|
|
}
|
|
if (do_newline) {
|
|
if (do_cr) output[op++] = '\r';
|
|
output[op++] = '\n';
|
|
}
|
|
} else if (p-estate.tailLen == len-2) {
|
|
int t = 0;
|
|
v = (((estate.tailLen > 1 ? estate.tail[t++] : input[p++]) & 0xff) << 10) |
|
|
(((estate.tailLen > 0 ? estate.tail[t++] : input[p++]) & 0xff) << 2);
|
|
estate.tailLen -= t;
|
|
output[op++] = estate.alphabet[(v >> 12) & 0x3f];
|
|
output[op++] = estate.alphabet[(v >> 6) & 0x3f];
|
|
output[op++] = estate.alphabet[v & 0x3f];
|
|
if (do_padding) {
|
|
output[op++] = '=';
|
|
}
|
|
if (do_newline) {
|
|
if (do_cr) output[op++] = '\r';
|
|
output[op++] = '\n';
|
|
}
|
|
} else if (do_newline && op > 0 && count != LINE_GROUPS) {
|
|
if (do_cr) output[op++] = '\r';
|
|
output[op++] = '\n';
|
|
}
|
|
|
|
assert estate.tailLen == 0;
|
|
assert p == len;
|
|
} else {
|
|
// Save the leftovers in tail to be consumed on the next
|
|
// call to encodeInternal.
|
|
|
|
if (p == len-1) {
|
|
estate.tail[estate.tailLen++] = input[p];
|
|
} else if (p == len-2) {
|
|
estate.tail[estate.tailLen++] = input[p];
|
|
estate.tail[estate.tailLen++] = input[p+1];
|
|
}
|
|
}
|
|
|
|
estate.op = op;
|
|
estate.count = count;
|
|
}
|
|
|
|
private Base64() { } // don't instantiate
|
|
}
|