Keep live view Caps Lock in sync on macOS

images/chromium-headful/client/src/utils/guacamole-keyboard.js

@@ -298,10 +298,6 @@ Guacamole.Keyboard = function Keyboard(element) {
         if (this.modifiers.meta && this.keysym !== 0xFFE7 && this.keysym !== 0xFFE8)
             this.keyupReliable = false;
 
-        // We cannot rely on receiving keyup for Caps Lock on certain platforms
-        else if (this.keysym === 0xFFE5 && quirks.capsLockKeyupUnreliable)
-            this.keyupReliable = false;
-
         // Determine whether default action for Alt+combinations must be prevented
         var prevent_alt = !this.modifiers.ctrl && !quirks.altIsTypableOnly;
 
@@ -1135,6 +1131,14 @@ Guacamole.Keyboard = function Keyboard(element) {
         if (!first)
             return null;
 
+        // macOS sends Caps Lock keydown only when enabling it and keyup only
+        // when disabling it, so each event is one full press of the key
+        if (first.keysym === 0xFFE5 && quirks.capsLockKeyupUnreliable) {
+            first.defaultPrevented = !guac_keyboard.press(0xFFE5);
+            guac_keyboard.release(0xFFE5);
+            return eventLog.shift();
+        }
+
         // Keydown event
         if (first instanceof KeydownEvent) {
 

images/chromium-headful/client/tests/guacamole-keyboard.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, test } from 'bun:test'
+import { afterEach, describe, expect, test } from 'bun:test'
 
 import createKeyboard from '../src/utils/guacamole-keyboard'
 
@@ -70,3 +70,45 @@ describe('GuacamoleKeyboard repeat handling', () => {
     expect(events).toEqual(['down:111', 'up:111', 'down:111', 'up:111'])
   })
 })
+
+describe('GuacamoleKeyboard Caps Lock handling', () => {
+  const platform = Object.getOwnPropertyDescriptor(navigator, 'platform')!
+
+  afterEach(() => {
+    Object.defineProperty(navigator, 'platform', platform)
+  })
+
+  function keyboardOn(platformName: string) {
+    Object.defineProperty(navigator, 'platform', { value: platformName, configurable: true })
+    const target = new KeyboardTarget()
+    const keyboard = createKeyboard(target as unknown as Element)
+    const events: string[] = []
+    keyboard.onkeydown = (key) => {
+      events.push(`down:${key}`)
+      return false
+    }
+    keyboard.onkeyup = (key) => events.push(`up:${key}`)
+    return { target, events }
+  }
+
+  test('forwards each macOS Caps Lock keydown and keyup as a full press', () => {
+    const { target, events } = keyboardOn('MacIntel')
+
+    target.dispatch('keydown', 'CapsLock', 20)
+    target.dispatch('keydown', 'a', 65)
+    target.dispatch('keypress', 'A', 65)
+    target.dispatch('keyup', 'a', 65)
+    target.dispatch('keyup', 'CapsLock', 20)
+
+    expect(events).toEqual(['down:65509', 'up:65509', 'down:65', 'up:65', 'down:65509', 'up:65509'])
+  })
+
+  test('keeps Caps Lock as a key press on other platforms', () => {
+    const { target, events } = keyboardOn('Win32')
+
+    target.dispatch('keydown', 'CapsLock', 20)
+    target.dispatch('keyup', 'CapsLock', 20)
+
+    expect(events).toEqual(['down:65509', 'up:65509'])
+  })
+})