core/base64.js

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 // From: http://hg.mozilla.org/mozilla-central/raw-file/ec10630b1a54/js/src/devtools/jint/sunspider/string-base64.js
   6
   7 /*jslint white: false */
   8 /*global console */
   9
  10 export default {
  11     /* Convert data (an array of integers) to a Base64 string. */
  12     toBase64Table : 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='.split(''),
  13     base64Pad     : '=',
  14
  15     encode: function (data) {
  16         "use strict";
  17         var result = '';
  18         var toBase64Table = this.toBase64Table;
  19         var length = data.length;
  20         var lengthpad = (length % 3);
  21         // Convert every three bytes to 4 ascii characters.
  22
  23         for (var i = 0; i < (length - 2); i += 3) {
  24             result += toBase64Table[data[i] >> 2];
  25             result += toBase64Table[((data[i] & 0x03) << 4) + (data[i + 1] >> 4)];
  26             result += toBase64Table[((data[i + 1] & 0x0f) << 2) + (data[i + 2] >> 6)];
  27             result += toBase64Table[data[i + 2] & 0x3f];
  28         }
  29
  30         // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
  31         var j = 0;
  32         if (lengthpad === 2) {
  33             j = length - lengthpad;
  34             result += toBase64Table[data[j] >> 2];
  35             result += toBase64Table[((data[j] & 0x03) << 4) + (data[j + 1] >> 4)];
  36             result += toBase64Table[(data[j + 1] & 0x0f) << 2];
  37             result += toBase64Table[64];
  38         } else if (lengthpad === 1) {
  39             j = length - lengthpad;
  40             result += toBase64Table[data[j] >> 2];
  41             result += toBase64Table[(data[j] & 0x03) << 4];
  42             result += toBase64Table[64];
  43             result += toBase64Table[64];
  44         }
  45
  46         return result;
  47     },
  48
  49     /* Convert Base64 data to a string */
  50     /* jshint -W013 */
  51     toBinaryTable : [
  52         -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  53         -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  54         -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
  55         52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-1,-1,
  56         -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
  57         15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
  58         -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
  59         41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
  60     ],
  61     /* jshint +W013 */
  62
  63     decode: function (data, offset) {
  64         "use strict";
  65         offset = typeof(offset) !== 'undefined' ? offset : 0;
  66         var toBinaryTable = this.toBinaryTable;
  67         var base64Pad = this.base64Pad;
  68         var result, result_length;
  69         var leftbits = 0; // number of bits decoded, but yet to be appended
  70         var leftdata = 0; // bits decoded, but yet to be appended
  71         var data_length = data.indexOf('=') - offset;
  72
  73         if (data_length < 0) { data_length = data.length - offset; }
  74
  75         /* Every four characters is 3 resulting numbers */
  76         result_length = (data_length >> 2) * 3 + Math.floor((data_length % 4) / 1.5);
  77         result = new Array(result_length);
  78
  79         // Convert one by one.
  80         for (var idx = 0, i = offset; i < data.length; i++) {
  81             var c = toBinaryTable[data.charCodeAt(i) & 0x7f];
  82             var padding = (data.charAt(i) === base64Pad);
  83             // Skip illegal characters and whitespace
  84             if (c === -1) {
  85                 console.error("Illegal character code " + data.charCodeAt(i) + " at position " + i);
  86                 continue;
  87             }
  88
  89             // Collect data into leftdata, update bitcount
  90             leftdata = (leftdata << 6) | c;
  91             leftbits += 6;
  92
  93             // If we have 8 or more bits, append 8 bits to the result
  94             if (leftbits >= 8) {
  95                 leftbits -= 8;
  96                 // Append if not padding.
  97                 if (!padding) {
  98                     result[idx++] = (leftdata >> leftbits) & 0xff;
  99                 }
 100                 leftdata &= (1 << leftbits) - 1;
 101             }
 102         }
 103
 104         // If there are any bits left, the base64 string was corrupted
 105         if (leftbits) {
 106             err = new Error('Corrupted base64 string');
 107             err.name = 'Base64-Error';
 108             throw err;
 109         }
 110
 111         return result;
 112     }
 113 }; /* End of Base64 namespace */