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