Updating shims for constrained environments (#944, #993).

packages/shims/src/index.js

@@ -1,9 +1,11 @@
 'use strict';
 
-var shims = [];
+(function() {
 
-// Shim String.prototype.normalize
-try {
+    var shims = [];
+
+    // Shim String.prototype.normalize
+    try {
         var missing = [];
 
         // Some platforms are missing certain normalization forms
@@ -28,53 +30,94 @@ try {
             shims.push("String.prototype.normalize (broken)");
             throw new Error('bad normalize');
         }
-} catch (error) {
+    } catch (error) {
         var unorm = require('./unorm.js');
         String.prototype.normalize = function(form) {
             var func = unorm[(form || 'NFC').toLowerCase()];
             if (!func) { throw new RangeError('invalid form - ' + form); }
             return func(this);
         }
-}
+    }
 
-// Shim atob and btoa
-var base64 = require('./base64.js');
-if (!global.atob) {
+    // Shim atob and btoa
+    var base64 = require('./base64.js');
+    if (!global.atob) {
         shims.push("atob");
         global.atob = base64.atob;
-}
-if (!global.btoa) {
+    }
+    if (!global.btoa) {
         shims.push("btoa");
         global.btoa = base64.btoa;
-}
+    }
 
-// Shim Promise
-// @TODO: Check first?
-if (window.Promise == null) {
-    var promise = require('./es6-promise.auto.js');
-}
-
-// Shim ArrayBuffer.isView
-if (!ArrayBuffer.isView) {
+    // Shim ArrayBuffer.isView
+    if (!ArrayBuffer.isView) {
         shims.push("ArrayBuffer.isView");
         ArrayBuffer.isView = function(obj) {
             // @TODO: This should probably check various instanceof aswell
             return !!(obj.buffer);
         }
-}
+    }
 
-// Shim nextTick
-if (!global.nextTick) {
+    // Shim nextTick
+    if (!global.nextTick) {
         shims.push("nextTick");
         global.nextTick = function (callback) { setTimeout(callback, 0); }
-}
+    }
 
-if (shims.length) {
+    // Shim crypto.getRandomValues
+    // @TOOD: Investigate: https://github.com/brix/crypto-js/issues/7
+    if (!global.crypto) { global.crypto = { }; }
+    if (!global.crypto.getRandomValues) {
+        shims.push("crypto.getRandomValues");
+        console.log("WARNING: This environment is missing a secure random source; generated private keys may be at risk, think VERY carefully about not adding a better secure source.");
+        global.crypto.getRandomValues = function(buffer) {
+            var start = Math.floor((new Date()).getTime()) % buffer.length;
+            for (var i = 0; i < buffer.length; i++) {
+                buffer[(start + i) % buffer.length] = Math.floor(Math.random() * 256);
+            }
+        }
+    }
+
+    // Shim FileReader.readAsArrayBuffer
+    // https://github.com/facebook/react-native/issues/21209
+    try {
+        var fr = new FileReader();
+        try {
+            fr.readAsArrayBuffer(new Blob([ "hello" ], { type: "text/plain" }));
+            return;
+        } catch (error) { }
+
+        shims.push("FileReader.prototype.readAsArrayBuffer");
+        FileReader.prototype.readAsArrayBuffer = function (blob) {
+            if (this.readyState === this.LOADING) throw new Error("InvalidStateError");
+            this._setReadyState(this.LOADING);
+            this._result = null;
+            this._error = null;
+            var fr = new FileReader();
+            fr.onloadend = () => {
+                var content = atob(fr.result.split(",").pop().trim());
+                var buffer = new ArrayBuffer(content.length);
+                var view = new Uint8Array(buffer);
+                view.set(Array.from(content).map(c => c.charCodeAt(0)));
+                this._result = buffer;
+                this._setReadyState(this.DONE);
+            };
+            fr.readAsDataURL(blob);
+        }
+
+    } catch (error) {
+        console.log("Missing FileReader; unsupported platform");
+    }
+
+    if (shims.length) {
         console.log("Shims Injected:");
         for (var i = 0; i < shims.length; i++) {
             console.log('  - ' + shims[i]);
         }
-}
+    }
+
+})();
+
+
 
-// @TOOD: Add crypto.rand?
-// - https://github.com/brix/crypto-js/issues/7