[fix] restore Linux keyboard injection

src/device_controller/keyboard/linux/keyboard_capturer.cpp

@@ -8,6 +8,7 @@
 #include <poll.h>
 
 #include "keyboard_converter.h"
+#include "linux_evdev_keycode.h"
 #include "platform.h"
 #include "rd_log.h"
 #include "windows_key_metadata.h"
@@ -17,6 +18,40 @@ namespace crossdesk {
 static OnKeyAction g_on_key_action = nullptr;
 static void* g_user_ptr = nullptr;
 
+static KeyCode ResolveX11Keycode(Display* display, int key_code,
+                                 uint32_t scan_code, bool extended) {
+  if (!display) {
+    return 0;
+  }
+
+  const auto key_it = vkCodeToX11KeySym.find(key_code);
+  if (key_it != vkCodeToX11KeySym.end()) {
+    const KeyCode x11_keycode =
+        XKeysymToKeycode(display, static_cast<KeySym>(key_it->second));
+    if (x11_keycode != 0) {
+      return x11_keycode;
+    }
+  }
+
+  // Some controllers can preserve the physical Windows scan code even when
+  // they cannot resolve a Windows virtual-key value. Xorg's evdev keycodes use
+  // the Linux input code plus the protocol-reserved offset of 8.
+  const int evdev_keycode =
+      ResolveLinuxEvdevKeycodeFromWindowsKey(key_code, scan_code, extended);
+  if (evdev_keycode < 0) {
+    return 0;
+  }
+
+  int min_keycode = 0;
+  int max_keycode = 0;
+  XDisplayKeycodes(display, &min_keycode, &max_keycode);
+  const int x11_keycode = evdev_keycode + 8;
+  if (x11_keycode < min_keycode || x11_keycode > max_keycode) {
+    return 0;
+  }
+  return static_cast<KeyCode>(x11_keycode);
+}
+
 static KeySym NormalizeKeySym(KeySym key_sym) {
   if (key_sym >= XK_a && key_sym <= XK_z) {
     return key_sym - XK_a + XK_A;
@@ -62,7 +97,16 @@ KeyboardCapturer::KeyboardCapturer()
   display_ = XOpenDisplay(nullptr);
   if (!display_) {
     LOG_ERROR("Failed to open X display.");
+    return;
   }
+
+  int event_base = 0;
+  int error_base = 0;
+  int major_version = 0;
+  int minor_version = 0;
+  x11_xtest_available_ =
+      XTestQueryExtension(display_, &event_base, &error_base, &major_version,
+                          &minor_version) != 0;
 }
 
 KeyboardCapturer::~KeyboardCapturer() {
@@ -70,8 +114,10 @@ KeyboardCapturer::~KeyboardCapturer() {
   CleanupWaylandPortal();
 
   if (display_) {
+    std::lock_guard<std::mutex> lock(x11_injection_mutex_);
     XCloseDisplay(display_);
     display_ = nullptr;
+    x11_xtest_available_ = false;
   }
 }
 
@@ -156,8 +202,6 @@ int KeyboardCapturer::Unhook() {
 
 int KeyboardCapturer::SendKeyboardCommand(int key_code, bool is_down,
                                           uint32_t scan_code, bool extended) {
-  (void)scan_code;
-  (void)extended;
   if (IsWaylandSession()) {
     if (!use_wayland_portal_ && !wayland_init_attempted_) {
       wayland_init_attempted_ = true;
@@ -181,12 +225,33 @@ int KeyboardCapturer::SendKeyboardCommand(int key_code, bool is_down,
     return -1;
   }
 
-  if (vkCodeToX11KeySym.find(key_code) != vkCodeToX11KeySym.end()) {
-    int x11_key_code = vkCodeToX11KeySym[key_code];
-    KeyCode keycode = XKeysymToKeycode(display_, x11_key_code);
-    XTestFakeKeyEvent(display_, keycode, is_down, CurrentTime);
-    XFlush(display_);
+  std::lock_guard<std::mutex> lock(x11_injection_mutex_);
+  if (!x11_xtest_available_) {
+    LOG_ERROR("XTest extension not available for keyboard injection");
+    return -2;
   }
+
+  const KeyCode x11_keycode =
+      ResolveX11Keycode(display_, key_code, scan_code, extended);
+  if (x11_keycode == 0) {
+    LOG_WARN(
+        "Cannot map remote keyboard event to X11 keycode, vk_code={}, "
+        "scan_code={}, extended={}",
+        key_code, scan_code, extended);
+    return -3;
+  }
+
+  if (!XTestFakeKeyEvent(display_, x11_keycode, is_down, CurrentTime)) {
+    LOG_ERROR(
+        "XTest keyboard injection failed, vk_code={}, scan_code={}, "
+        "extended={}, x11_keycode={}, is_down={}",
+        key_code, scan_code, extended, static_cast<int>(x11_keycode), is_down);
+    return -4;
+  }
+
+  // Complete the request before reporting success to the keyboard-state
+  // reconciler. This also makes X11 protocol errors observable immediately.
+  XSync(display_, False);
   return 0;
 }
 }  // namespace crossdesk

src/device_controller/keyboard/linux/keyboard_capturer.h

@@ -10,6 +10,7 @@
 #include <atomic>
 #include <cstdint>
 #include <functional>
+#include <mutex>
 #include <string>
 #include <thread>
 
@@ -49,6 +50,8 @@ class KeyboardCapturer : public DeviceController {
   unsigned long root_;
   std::atomic<bool> running_;
   std::thread event_thread_;
+  std::mutex x11_injection_mutex_;
+  bool x11_xtest_available_ = false;
   bool use_wayland_portal_ = false;
   bool wayland_init_attempted_ = false;
   DBusConnection* dbus_connection_ = nullptr;

src/device_controller/keyboard/linux/keyboard_capturer_wayland.cpp

@@ -611,6 +611,7 @@ int KeyboardCapturer::SendWaylandKeyboardCommand(int key_code, bool is_down,
   // Prefer keycode injection to preserve physical-key semantics and avoid
   // implicit Shift interpretation for uppercase keysyms.
   if (display_) {
+    std::lock_guard<std::mutex> lock(x11_injection_mutex_);
     const int keysym = key_it->second;
     const KeyCode x11_keycode =
         XKeysymToKeycode(display_, static_cast<KeySym>(keysym));

tests/linux_keyboard_x11_integration_test.cpp

@@ -0,0 +1,52 @@
+#include <X11/Xlib.h>
+
+#include <chrono>
+#include <cstdio>
+#include <thread>
+
+#include "keyboard_capturer.h"
+
+int main() {
+  Display* receiver = XOpenDisplay(nullptr);
+  if (!receiver) {
+    std::fprintf(stderr, "open display failed\n");
+    return 1;
+  }
+
+  const int screen = DefaultScreen(receiver);
+  Window window = XCreateSimpleWindow(receiver, RootWindow(receiver, screen),
+                                      0, 0, 100, 100, 0, 0, 0);
+  XSelectInput(receiver, window, KeyPressMask | KeyReleaseMask);
+  XMapWindow(receiver, window);
+  XSync(receiver, False);
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  XSetInputFocus(receiver, window, RevertToParent, CurrentTime);
+  XSync(receiver, False);
+
+  crossdesk::KeyboardCapturer keyboard;
+  // Exercise the scan-code fallback: the controller supplied no usable VK,
+  // but did preserve the set-1 scan code for the A key.
+  const int down = keyboard.SendKeyboardCommand(0, true, 0x1E, false);
+  const int up = keyboard.SendKeyboardCommand(0, false, 0x1E, false);
+
+  bool saw_down = false;
+  bool saw_up = false;
+  const auto deadline = std::chrono::steady_clock::now() +
+                        std::chrono::seconds(2);
+  while (std::chrono::steady_clock::now() < deadline &&
+         (!saw_down || !saw_up)) {
+    while (XPending(receiver) > 0) {
+      XEvent event{};
+      XNextEvent(receiver, &event);
+      saw_down = saw_down || event.type == KeyPress;
+      saw_up = saw_up || event.type == KeyRelease;
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+  }
+
+  XDestroyWindow(receiver, window);
+  XCloseDisplay(receiver);
+  std::printf("down_ret=%d up_ret=%d saw_down=%d saw_up=%d\n", down, up,
+              saw_down, saw_up);
+  return down == 0 && up == 0 && saw_down && saw_up ? 0 : 2;
+}

xmake/targets.lua

@@ -197,6 +197,14 @@ function setup_targets()
                 "src/device_controller/keyboard/linux", {public = true})
         end
 
+    if is_os("linux") then
+        target("linux_keyboard_x11_integration_test")
+            set_kind("binary")
+            set_default(false)
+            add_deps("device_controller")
+            add_files("tests/linux_keyboard_x11_integration_test.cpp")
+    end
+
     target("thumbnail")
         set_kind("object")
         add_packages("libyuv", "openssl3")