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