Refactor platform serialization to make it easier for forks

Also allows extensions an easy way to access it

src/engine/runtime.js

@@ -22,6 +22,7 @@ const xmlEscape = require('../util/xml-escape');
 const ScratchLinkWebSocket = require('../util/scratch-link-websocket');
 const FontManager = require('./tw-font-manager');
 const fetchWithTimeout = require('../util/fetch-with-timeout');
+const platform = require('./tw-platform.js');
 
 // Virtual I/O devices.
 const Clock = require('../io/clock');
@@ -439,6 +440,11 @@ class Runtime extends EventEmitter {
          */
         this.origin = null;
 
+        /**
+         * Metadata about the platform this VM is part of.
+         */
+        this.platform = Object.assign({}, platform);
+
         this._initScratchLink();
 
         this.resetRunId();

src/engine/tw-platform.js

@@ -0,0 +1,7 @@
+// Forks should change this.
+// This can be accessed externally on `vm.runtime.platform`
+
+module.exports = {
+    name: 'TurboWarp',
+    url: 'https://turbowarp.org/'
+};

src/serialization/sb3.js

@@ -794,11 +794,8 @@ const serialize = function (runtime, targetId, {allowOptimization = true} = {})
     // TW: Never include full user agent to slightly improve user privacy
     // if (typeof navigator !== 'undefined') meta.agent = navigator.userAgent;
 
-    // TW: Attach platform information (should be changed for forks of TurboWarp)
-    const platform = Object.create(null);
-    platform.name = 'TurboWarp';
-    platform.url = 'https://turbowarp.org/';
-    meta.platform = platform;
+    // TW: Attach copy of platform information
+    meta.platform = Object.assign({}, runtime.platform);
 
     // Assemble payload and return
     obj.meta = meta;

test/integration/tw_platform.js

@@ -0,0 +1,26 @@
+const {test} = require('tap');
+const VM = require('../../src/virtual-machine');
+const platform = require('../../src/engine/tw-platform');
+
+test('the internal object', t => {
+    // the idea with this test is to make it harder for forks to screw up modifying the file
+    t.type(platform.name, 'string');
+    t.type(platform.url, 'string');
+    t.end();
+});
+
+test('vm property', t => {
+    const vm = new VM();
+    t.same(vm.runtime.platform, platform, 'copy of tw-platform.js');
+    t.not(vm.runtime.platform, platform, 'not the same object as tw-platform.js');
+    t.end();
+});
+
+test('sanitize', t => {
+    const vm = new VM();
+    vm.runtime.platform.name += ' - test';
+    const json = JSON.parse(vm.toJSON());
+    t.same(json.meta.platform, vm.runtime.platform, 'copy of runtime.platform');
+    t.not(json.meta.platform, vm.runtime.platform, 'not the same object as runtime.platform');
+    t.end();
+});