mirror of https://github.com/M66B/FairEmail.git
191 lines
7.5 KiB
Java
191 lines
7.5 KiB
Java
package com.bugsnag.android.repackaged.dslplatform.json;
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import java.util.Arrays;
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/** A very fast and memory efficient class to encode and decode to and from BASE64 in full accordance
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* with RFC 2045.<br><br>
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* On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is about 10 times faster
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* on small arrays (10 - 1000 bytes) and 2-3 times as fast on larger arrays (10000 - 1000000 bytes)
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* compared to <code>sun.misc.Encoder()/Decoder()</code>.<br><br>
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*
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* On byte arrays the encoder is about 20% faster than Jakarta Commons Base64 Codec for encode and
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* about 50% faster for decoding large arrays. This implementation is about twice as fast on very small
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* arrays (< 30 bytes). If source/destination is a <code>String</code> this
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* version is about three times as fast due to the fact that the Commons Codec result has to be recoded
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* to a <code>String</code> from <code>byte[]</code>, which is very expensive.<br><br>
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*
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* This encode/decode algorithm doesn't create any temporary arrays as many other codecs do, it only
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* allocates the resulting array. This produces less garbage and it is possible to handle arrays twice
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* as large as algorithms that create a temporary array. (E.g. Jakarta Commons Codec). It is unknown
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* whether Sun's <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but since performance
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* is quite low it probably does.<br><br>
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*
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* The encoder produces the same output as the Sun one except that the Sun's encoder appends
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* a trailing line separator if the last character isn't a pad. Unclear why but it only adds to the
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* length and is probably a side effect. Both are in conformance with RFC 2045 though.<br>
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* Commons codec seem to always att a trailing line separator.<br><br>
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*
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* <b>Note!</b>
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* The encode/decode method pairs (types) come in three versions with the <b>exact</b> same algorithm and
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* thus a lot of code redundancy. This is to not create any temporary arrays for transcoding to/from different
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* format types. The methods not used can simply be commented out.<br><br>
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*
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* There is also a "fast" version of all decode methods that works the same way as the normal ones, but
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* har a few demands on the decoded input. Normally though, these fast verions should be used if the source if
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* the input is known and it hasn't bee tampered with.<br><br>
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*
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* If you find the code useful or you find a bug, please send me a note at base64 @ miginfocom . com.
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*
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* Licence (BSD):
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* ==============
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*
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* Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this list
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* of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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* Neither the name of the MiG InfoCom AB nor the names of its contributors may be
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* used to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* @version 2.2
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* @author Mikael Grev
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* Date: 2004-aug-02
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* Time: 11:31:11
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*/
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abstract class Base64 {
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private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
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private static final byte[] BA;
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private static final int[] IA = new int[256];
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static {
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Arrays.fill(IA, -1);
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for (int i = 0, iS = CA.length; i < iS; i++) {
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IA[CA[i]] = i;
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}
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IA['='] = 0;
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BA = new byte[CA.length];
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for (int i = 0; i < CA.length; i++) {
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BA[i] = (byte)CA[i];
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}
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}
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static int encodeToBytes(byte[] sArr, byte[] dArr, final int start) {
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final int sLen = sArr.length;
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final int eLen = (sLen / 3) * 3; // Length of even 24-bits.
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final int dLen = ((sLen - 1) / 3 + 1) << 2; // Returned character count
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// Encode even 24-bits
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for (int s = 0, d = start; s < eLen;) {
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// Copy next three bytes into lower 24 bits of int, paying attension to sign.
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int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
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// Encode the int into four chars
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dArr[d++] = BA[(i >>> 18) & 0x3f];
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dArr[d++] = BA[(i >>> 12) & 0x3f];
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dArr[d++] = BA[(i >>> 6) & 0x3f];
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dArr[d++] = BA[i & 0x3f];
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}
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// Pad and encode last bits if source isn't even 24 bits.
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int left = sLen - eLen; // 0 - 2.
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if (left > 0) {
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// Prepare the int
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int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
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// Set last four chars
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dArr[start + dLen - 4] = BA[i >> 12];
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dArr[start + dLen - 3] = BA[(i >>> 6) & 0x3f];
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dArr[start + dLen - 2] = left == 2 ? BA[i & 0x3f] : (byte)'=';
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dArr[start + dLen - 1] = '=';
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}
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return dLen;
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}
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static int findEnd(final byte[] sArr, final int start) {
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for (int i = start; i < sArr.length; i++)
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if (IA[sArr[i] & 0xff] < 0)
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return i;
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return sArr.length;
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}
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private final static byte[] EMPTY_ARRAY = new byte[0];
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static byte[] decodeFast(final byte[] sArr, final int start, final int end) {
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// Check special case
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int sLen = end - start;
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if (sLen == 0)
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return EMPTY_ARRAY;
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int sIx = start, eIx = end - 1; // Start and end index after trimming.
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// Trim illegal chars from start
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while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0) {
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sIx++;
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}
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// Trim illegal chars from end
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while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0) {
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eIx--;
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}
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// get the padding count (=) (0, 1 or 2)
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final int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
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final int cCnt = eIx - sIx + 1; // Content count including possible separators
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final int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
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final int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
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final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
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// Decode all but the last 0 - 2 bytes.
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int d = 0;
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for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
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// Assemble three bytes into an int from four "valid" characters.
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int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];
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// Add the bytes
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dArr[d++] = (byte) (i >> 16);
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dArr[d++] = (byte) (i >> 8);
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dArr[d++] = (byte) i;
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// If line separator, jump over it.
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if (sepCnt > 0 && ++cc == 19) {
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sIx += 2;
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cc = 0;
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}
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}
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if (d < len) {
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// Decode last 1-3 bytes (incl '=') into 1-3 bytes
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int i = 0;
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for (int j = 0; sIx <= eIx - pad; j++) {
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i |= IA[sArr[sIx++]] << (18 - j * 6);
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}
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for (int r = 16; d < len; r -= 8) {
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dArr[d++] = (byte) (i >> r);
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}
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}
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return dArr;
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}
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}
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