electron · MarshallOfSound · Oct 18, 2019 · Sep 20, 2019 · Sep 20, 2019 · Sep 20, 2019
diff --git a/default_app/index.html b/default_app/index.html
@@ -2,10 +2,9 @@
 
 <head>
   <title>Electron</title>
-  <meta http-equiv="Content-Security-Policy" content="default-src 'none'; script-src 'self'; style-src 'self'; img-src 'self'; connect-src 'self'" />
+  <meta http-equiv="Content-Security-Policy" content="default-src 'none'; script-src 'sha256-6PH54BfkNq/EMMhUY7nhHf3c+AxloOwfy7hWyT01CM8='; style-src 'self'; img-src 'self'; connect-src 'self'" />
   <link href="./styles.css" type="text/css" rel="stylesheet" />
   <link href="./octicon/build.css" type="text/css" rel="stylesheet" />
-  <script defer src="./index.js"></script>
 </head>
 
 <body>
@@ -84,6 +83,9 @@ <h4>Forge</h4>
       </div>
     </div>
   </nav>
+  <script>
+    window.electronDefaultApp.initialize()
+  </script>
 </body>
 
 </html>
diff --git a/default_app/index.ts b/default_app/index.ts
diff --git a/default_app/preload.ts b/default_app/preload.ts
@@ -1,4 +1,31 @@
-import { ipcRenderer } from 'electron'
+import { ipcRenderer, contextBridge } from 'electron'
+
+async function getOcticonSvg (name: string) {
+  try {
+    const response = await fetch(`octicon/${name}.svg`)
+    const div = document.createElement('div')
+    div.innerHTML = await response.text()
+    return div
+  } catch {
+    return null
+  }
+}
+
+async function loadSVG (element: HTMLSpanElement) {
+  for (const cssClass of element.classList) {
+    if (cssClass.startsWith('octicon-')) {
+      const icon = await getOcticonSvg(cssClass.substr(8))
+      if (icon) {
+        for (const elemClass of element.classList) {
+          icon.classList.add(elemClass)
+        }
+        element.before(icon)
+        element.remove()
+        break
+      }
+    }
+  }
+}
 
 async function initialize () {
   const electronPath = await ipcRenderer.invoke('bootstrap')
@@ -15,6 +42,12 @@ async function initialize () {
   replaceText('.node-version', `Node v${process.versions.node}`)
   replaceText('.v8-version', `v8 v${process.versions.v8}`)
   replaceText('.command-example', `${electronPath} path-to-app`)
+
+  for (const element of document.querySelectorAll<HTMLSpanElement>('.octicon')) {
+    loadSVG(element)
+  }
 }
 
-document.addEventListener('DOMContentLoaded', initialize)
+contextBridge.exposeInMainWorld('electronDefaultApp', {
+  initialize
+})
diff --git a/docs/api/context-bridge.md b/docs/api/context-bridge.md
@@ -0,0 +1,111 @@
+# contextBridge
+
+> Create a safe, bi-directional, synchronous bridge across isolated contexts
+
+Process: [Renderer](../glossary.md#renderer-process)
+
+An example of exposing an API to a renderer from an isolated preload script is given below:
+
+```javascript
+// Preload (Isolated World)
+const { contextBridge, ipcRenderer } = require('electron')
+
+contextBridge.exposeInMainWorld(
+  'electron',
+  {
+    doThing: () => ipcRenderer.send('do-a-thing')
+  }
+)
+```
+
+```javascript
+// Renderer (Main World)
+
+window.electron.doThing()
+```
+
+## Glossary
+
+### Main World
+
+The "Main World" is the javascript context that your main renderer code runs in.  By default the page you load in your renderer
+executes code in this world.
+
+### Isolated World
+
+When `contextIsolation` is enabled in your `webPreferences` your `preload` scripts run in an "Isolated World".  You can read more about
+context isolation and what it affects in the [BrowserWindow](browser-window.md) docs.
+
+## Methods
+
+The `contextBridge` module has the following methods:
+
+### `contextBridge.exposeInMainWorld(apiKey, api)`
+
+* `apiKey` String - The key to inject the API onto `window` with.  The API will be accessible on `window[apiKey]`.
+* `api` Record<String, any> - Your API object, more information on what this API can be and how it works is available below.
+
+## Usage
+
+### API Objects
+
+The `api` object provided to [`exposeInMainWorld`](#contextbridgeexposeinmainworldapikey-api) must be an object
+whose keys are strings and values are a `Function`, `String`, `Number`, `Array`, `Boolean` or another nested object that meets the same conditions.
+
+`Function` values are proxied to the other context and all other values are **copied** and **frozen**.  I.e. Any data / primitives sent in
+the API object become immutable and updates on either side of the bridge do not result in an update on the other side.
+
+An example of a complex API object is shown below.
+
+```javascript
+const { contextBridge } = require('electron')
+
+contextBridge.exposeInMainWorld(
+  'electron',
+  {
+    doThing: () => ipcRenderer.send('do-a-thing'),
+    myPromises: [Promise.resolve(), Promise.reject(new Error('whoops'))],
+    anAsyncFunction: async () => 123,
+    data: {
+      myFlags: ['a', 'b', 'c'],
+      bootTime: 1234
+    },
+    nestedAPI: {
+      evenDeeper: {
+        youCanDoThisAsMuchAsYouWant: {
+          fn: () => ({
+            returnData: 123
+          })
+        }
+      }
+    }
+  }
+)
+```
+
+### API Functions
+
+`Function` values that you bind through the `contextBridge` are proxied through Electron to ensure that contexts remain isolated.  This
+results in some key limitations that we've outlined below.
+
+#### Parameter / Error / Return Type support
+
+Because parameters, errors and return values are **copied** when they are sent over the bridge there are only certain types that can be used.
+At a high level if the type you want to use can be serialized and un-serialized into the same object it will work.  A table of type support
+has been included below for completeness.
+
+| Type | Complexity | Parameter Support | Return Value Support | Limitations |
+| ---- | ---------- | ----------------- | -------------------- | ----------- |
+| `String` | Simple | ✅ | ✅ | N/A |
+| `Number` | Simple | ✅ | ✅ | N/A |
+| `Boolean` | Simple | ✅ | ✅ | N/A |
+| `Object` | Complex | ✅ | ✅ | Keys must be supported "Simple" types in this table.  Values must be supported in this table.  Prototype modifications are dropped.  Sending custom classes will copy values but not the prototype. |
+| `Array` | Complex | ✅ | ✅ | Same limitations as the `Object` type |
+| `Error` | Complex | ✅ | ✅ | Errors that are thrown are also copied, this can result in the message and stack trace of the error changing slightly due to being thrown in a different context |
+| `Promise` | Complex | ✅ | ✅ | Promises are only proxied if they are a the return value or exact parameter.  Promises nested in arrays or obejcts will be dropped. |
+| `Function` | Complex | ✅ | ✅ | Prototype modifications are dropped.  Sending classes or constructors will not work. |
+| [Cloneable Types](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) | Simple | ✅ | ✅ | See the linked document on cloneable types |
+| `Symbol` | N/A | ❌ | ❌ | Symbols cannot be copied across contexts so they are dropped |
+
+
+If the type you care about is not in the above table it is probably not supported.
diff --git a/filenames.auto.gni b/filenames.auto.gni
@@ -14,6 +14,7 @@ auto_filenames = {
     "docs/api/command-line-switches.md",
     "docs/api/command-line.md",
     "docs/api/content-tracing.md",
+    "docs/api/context-bridge.md",
     "docs/api/cookies.md",
     "docs/api/crash-reporter.md",
     "docs/api/debugger.md",
@@ -142,6 +143,7 @@ auto_filenames = {
     "lib/common/remote/buffer-utils.ts",
     "lib/common/remote/is-promise.ts",
     "lib/common/web-view-methods.ts",
+    "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.js",
     "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/ipc-renderer.ts",
@@ -303,6 +305,7 @@ auto_filenames = {
     "lib/common/remote/is-promise.ts",
     "lib/common/reset-search-paths.ts",
     "lib/common/web-view-methods.ts",
+    "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.js",
     "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/exports/electron.ts",
@@ -352,6 +355,7 @@ auto_filenames = {
     "lib/common/remote/buffer-utils.ts",
     "lib/common/remote/is-promise.ts",
     "lib/common/reset-search-paths.ts",
+    "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.js",
     "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/exports/electron.ts",

diff --git a/filenames.gni b/filenames.gni
@@ -1,7 +1,6 @@
 filenames = {
   default_app_ts_sources = [
     "default_app/default_app.ts",
-    "default_app/index.ts",
     "default_app/main.ts",
     "default_app/preload.ts",
   ]
@@ -554,6 +553,10 @@ filenames = {
     "shell/common/promise_util.cc",
     "shell/common/skia_util.h",
     "shell/common/skia_util.cc",
+    "shell/renderer/api/context_bridge/render_frame_context_bridge_store.cc",
+    "shell/renderer/api/context_bridge/render_frame_context_bridge_store.h",
+    "shell/renderer/api/atom_api_context_bridge.cc",
+    "shell/renderer/api/atom_api_context_bridge.h",
     "shell/renderer/api/atom_api_renderer_ipc.cc",
     "shell/renderer/api/atom_api_spell_check_client.cc",
     "shell/renderer/api/atom_api_spell_check_client.h",

diff --git a/lib/renderer/api/context-bridge.ts b/lib/renderer/api/context-bridge.ts
@@ -0,0 +1,20 @@
+const { hasSwitch } = process.electronBinding('command_line')
+const binding = process.electronBinding('context_bridge')
+
+const contextIsolationEnabled = hasSwitch('context-isolation')
+
+const checkContextIsolationEnabled = () => {
+  if (!contextIsolationEnabled) throw new Error('contextBridge API can only be used when contextIsolation is enabled')
+}
+
+const contextBridge = {
+  exposeInMainWorld: (key: string, api: Record<string, any>) => {
+    checkContextIsolationEnabled()
+    return binding.exposeAPIInMainWorld(key, api)
+  },
+  debugGC: () => binding._debugGCMaps({})
+}
+
+if (!binding._debugGCMaps) delete contextBridge.debugGC
+
+export default contextBridge
diff --git a/lib/renderer/api/module-list.ts b/lib/renderer/api/module-list.ts
@@ -5,6 +5,7 @@ const enableRemoteModule = v8Util.getHiddenValue<boolean>(global, 'enableRemoteM
 
 // Renderer side modules, please sort alphabetically.
 export const rendererModuleList: ElectronInternal.ModuleEntry[] = [
+  { name: 'contextBridge', loader: () => require('./context-bridge') },
   { name: 'crashReporter', loader: () => require('./crash-reporter') },
   { name: 'ipcRenderer', loader: () => require('./ipc-renderer') },
   { name: 'webFrame', loader: () => require('./web-frame') }

diff --git a/lib/sandboxed_renderer/api/module-list.ts b/lib/sandboxed_renderer/api/module-list.ts
@@ -1,6 +1,10 @@
 const features = process.electronBinding('features')
 
 export const moduleList: ElectronInternal.ModuleEntry[] = [
+  {
+    name: 'contextBridge',
+    loader: () => require('@electron/internal/renderer/api/context-bridge')
+  },
   {
     name: 'crashReporter',
     loader: () => require('@electron/internal/renderer/api/crash-reporter')

diff --git a/native_mate/native_mate/arguments.h b/native_mate/native_mate/arguments.h
@@ -31,7 +31,7 @@ class Arguments {
 
   template <typename T>
   bool GetHolder(T* out) {
-    return ConvertFromV8(isolate_, info_->Holder(), out);
+    return mate::ConvertFromV8(isolate_, info_->Holder(), out);
   }
 
   template <typename T>
@@ -57,7 +57,7 @@ class Arguments {
       return false;
     }
     v8::Local<v8::Value> val = (*info_)[next_];
-    bool success = ConvertFromV8(isolate_, val, out);
+    bool success = mate::ConvertFromV8(isolate_, val, out);
     if (success)
       next_++;
     return success;

diff --git a/native_mate/native_mate/dictionary.h b/native_mate/native_mate/dictionary.h
@@ -40,6 +40,12 @@ class Dictionary {
 
   static Dictionary CreateEmpty(v8::Isolate* isolate);
 
+  bool Has(base::StringPiece key) const {
+    v8::Local<v8::Context> context = isolate_->GetCurrentContext();
+    v8::Local<v8::String> v8_key = StringToV8(isolate_, key);
+    return internal::IsTrue(GetHandle()->Has(context, v8_key));
+  }
+
   template <typename T>
   bool Get(base::StringPiece key, T* out) const {
     // Check for existence before getting, otherwise this method will always
@@ -76,6 +82,17 @@ class Dictionary {
     return !result.IsNothing() && result.FromJust();
   }
 
+  template <typename T>
+  bool SetReadOnlyNonConfigurable(base::StringPiece key, T val) {
+    v8::Local<v8::Value> v8_value;
+    if (!TryConvertToV8(isolate_, val, &v8_value))
+      return false;
+    v8::Maybe<bool> result = GetHandle()->DefineOwnProperty(
+        isolate_->GetCurrentContext(), StringToV8(isolate_, key), v8_value,
+        static_cast<v8::PropertyAttribute>(v8::ReadOnly | v8::DontDelete));
+    return !result.IsNothing() && result.FromJust();
+  }
+
   template <typename T>
   bool SetMethod(base::StringPiece key, const T& callback) {
     return GetHandle()

diff --git a/shell/common/node_bindings.cc b/shell/common/node_bindings.cc
@@ -66,6 +66,7 @@
   V(atom_common_screen)              \
   V(atom_common_shell)               \
   V(atom_common_v8_util)             \
+  V(atom_renderer_context_bridge)    \
   V(atom_renderer_ipc)               \
   V(atom_renderer_web_frame)
 

diff --git a/shell/common/promise_util.h b/shell/common/promise_util.h
@@ -126,6 +126,16 @@ class Promise {
     return GetInner()->Reject(GetContext(), v8::Undefined(isolate()));
   }
 
+  v8::Maybe<bool> Reject(v8::Local<v8::Value> exception) {
+    v8::HandleScope handle_scope(isolate());
+    v8::MicrotasksScope script_scope(isolate(),
+                                     v8::MicrotasksScope::kRunMicrotasks);
+    v8::Context::Scope context_scope(
+        v8::Local<v8::Context>::New(isolate(), GetContext()));
+
+    return GetInner()->Reject(GetContext(), exception);
+  }
+
   template <typename... ResolveType>
   v8::MaybeLocal<v8::Promise> Then(
       base::OnceCallback<void(ResolveType...)> cb) {