Refine base64 decode to support decode UTF8 data, use TypedArray to h…

…andle binary data

Libraries/Network/XMLHttpRequest.js

@@ -17,6 +17,7 @@ const EventTarget = require('event-target-shim');
 const invariant = require('fbjs/lib/invariant');
 const utf8 = require('utf8');
 const warning = require('fbjs/lib/warning');
+const base64 = require('base64-js');
 
 type ResponseType = '' | 'arraybuffer' | 'blob' | 'document' | 'json' | 'text';
 type Response = ?Object | string;
@@ -103,6 +104,7 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
   _response: string | ?Object;
   _responseType: ResponseType;
   _responseText: string = '';
+  _responseBytes: Uint8Array;
   _sent: boolean;
   _url: ?string = null;
   _timedOut: boolean = false;
@@ -125,7 +127,8 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
     this._hasError = false;
     this._headers = {};
     this._responseText = '';
-    this._responseType = '';
+    this._responseBytes = undefined;
+    // this._responseType = '';
     this._sent = false;
     this._lowerCaseResponseHeaders = {};
 
@@ -199,13 +202,12 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
         break;
 
       case 'arraybuffer':
-        this._cachedResponse = toArrayBuffer(
-          this._responseText, this.getResponseHeader('content-type') || '');
+        this._cachedResponse = this._responseBytes.buffer;
         break;
 
       case 'blob':
         this._cachedResponse = new global.Blob(
-          [this._responseText],
+          [this._responseBytes],
           {type: this.getResponseHeader('content-type') || ''}
         );
         break;
@@ -261,12 +263,24 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
   }
 
   __didReceiveData(requestId: number, responseText: string): void {
-    responseText = atob(responseText);
     if (requestId === this._requestId) {
-      if (!this._responseText) {
-        this._responseText = responseText;
+      if (this.responseType == '' || this.responseType == 'text') {
+        responseText = btou(atob(responseText));
+        if (!this._responseText) {
+          this._responseText = responseText;
+        } else {
+          this._responseText += responseText;
+        }
       } else {
-        this._responseText += responseText;
+        let bytes = base64.toByteArray(responseText);
+        if (!this._responseBytes) {
+          this._responseBytes = bytes;
+        } else {
+          let buffer = new Uint8Array(this._responseBytes.byteLength + bytes.byteLength);
+          buffer.set(this._responseBytes, 0);
+          buffer.set(bytes, this._responseBytes.byteLength);
+          this._responseBytes = buffer;
+        }
       }
       this._cachedResponse = undefined; // force lazy recomputation
       this.setReadyState(this.LOADING);
@@ -473,4 +487,38 @@ function toArrayBuffer(text: string, contentType: string): ArrayBuffer {
   }
 }
 
+// from https://github.com/dankogai/js-base64/blob/master/base64.js
+const re_btou = new RegExp([
+  '[\xC0-\xDF][\x80-\xBF]',
+  '[\xE0-\xEF][\x80-\xBF]{2}',
+  '[\xF0-\xF7][\x80-\xBF]{3}'].join('|'), 'g');
+
+var cb_btou = function(cccc) {
+  switch(cccc.length) {
+  case 4:
+    var cp = ((0x07 & cccc.charCodeAt(0)) << 18)
+      |    ((0x3f & cccc.charCodeAt(1)) << 12)
+      |    ((0x3f & cccc.charCodeAt(2)) <<  6)
+      |     (0x3f & cccc.charCodeAt(3)),
+    offset = cp - 0x10000;
+    return (String.fromCharCode((offset  >>> 10) + 0xD800)
+            + String.fromCharCode((offset & 0x3FF) + 0xDC00));
+  case 3:
+    return String.fromCharCode(
+      ((0x0f & cccc.charCodeAt(0)) << 12)
+        | ((0x3f & cccc.charCodeAt(1)) << 6)
+        |  (0x3f & cccc.charCodeAt(2))
+  );
+  default:
+    return  String.fromCharCode(
+      ((0x1f & cccc.charCodeAt(0)) << 6)
+        |  (0x3f & cccc.charCodeAt(1))
+    );
+  }
+}
+
+function btou(s) {
+  return s.replace(re_btou, cb_btou);
+}
+
 module.exports = XMLHttpRequest;