WindowManager: Basic support for system keymap switching

Author: https://github.com/TSultanov
Commit: https://github.com/SerenityOS/serenity/commit/68a01f0e273
Pull-request: https://github.com/SerenityOS/serenity/pull/12010

Userland/Services/WindowServer/CMakeLists.txt

@@ -36,6 +36,7 @@ set(SOURCES
     WindowManagerServerEndpoint.h
     WindowManagerClientEndpoint.h
     WMClientConnection.cpp
+    KeymapSwitcher.cpp
 )
 
 serenity_bin(WindowServer)

Userland/Services/WindowServer/KeymapSwitcher.cpp

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2021, Timur Sultanov <SultanovTS@yandex.ru>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonObject.h>
+#include <LibCore/File.h>
+#include <WindowServer/KeymapSwitcher.h>
+#include <spawn.h>
+#include <unistd.h>
+
+namespace WindowServer {
+
+static KeymapSwitcher* s_the;
+
+KeymapSwitcher& KeymapSwitcher::the()
+{
+    VERIFY(s_the);
+    return *s_the;
+}
+
+KeymapSwitcher::KeymapSwitcher()
+{
+    s_the = this;
+}
+
+KeymapSwitcher::~KeymapSwitcher()
+{
+}
+
+void KeymapSwitcher::refresh()
+{
+    m_keymaps.clear();
+
+    //TODO: load keymaps from file
+    m_keymaps.append("en-us");
+    m_keymaps.append("ru");
+}
+
+void KeymapSwitcher::next_keymap()
+{
+    refresh();
+
+    if (m_keymaps.is_empty()) {
+        dbgln("No keymaps loaded - leaving system keymap unchanged");
+        return; // TODO: figure out what to do when there is no keymap configured
+    }
+
+    auto current_keymap_name = get_current_keymap();
+
+    dbgln("Current system keymap: {}", current_keymap_name);
+
+    auto it = m_keymaps.find_if([&](const auto& enumerator) {
+        return enumerator == current_keymap_name;
+    });
+
+    if (it.is_end()) {
+        auto first_keymap = m_keymaps.first();
+        dbgln("Cannot find current keymap in the keymap list - setting first available ({})", first_keymap);
+        setkeymap(first_keymap);
+    } else {
+        it++;
+
+        if (it.is_end()) {
+            it = m_keymaps.begin();
+        }
+
+        dbgln("Setting system keymap to: {}", *it);
+        setkeymap(*it);
+    }
+}
+
+String KeymapSwitcher::get_current_keymap() const
+{
+    auto proc_keymap = Core::File::construct("/proc/keymap");
+    if (!proc_keymap->open(Core::OpenMode::ReadOnly))
+        VERIFY_NOT_REACHED();
+
+    auto json = JsonValue::from_string(proc_keymap->read_all()).release_value_but_fixme_should_propagate_errors();
+    auto const& keymap_object = json.as_object();
+    VERIFY(keymap_object.has("keymap"));
+    auto keymap = keymap_object.get("keymap").to_string();
+    dbgln("Current keymap is: {}", keymap);
+
+    return keymap;
+}
+
+void KeymapSwitcher::setkeymap(const AK::String& keymap)
+{
+    pid_t child_pid;
+    const char* argv[] = { "/bin/keymap", keymap.characters(), nullptr };
+    if ((errno = posix_spawn(&child_pid, "/bin/keymap", nullptr, nullptr, const_cast<char**>(argv), environ))) {
+        perror("posix_spawn");
+        dbgln("Failed to call /bin/keymap, error: {} ({})", errno, strerror(errno));
+    }
+}
+
+}

Userland/Services/WindowServer/KeymapSwitcher.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021, Timur Sultanov <SultanovTS@yandex.ru>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <AK/WeakPtr.h>
+#include <LibCore/Object.h>
+#include <LibKeyboard/CharacterMap.h>
+
+namespace WindowServer {
+
+class KeymapSwitcher final : public Core::Object {
+    C_OBJECT(KeymapSwitcher)
+public:
+    static KeymapSwitcher& the();
+
+    virtual ~KeymapSwitcher() override;
+
+    void refresh();
+
+    void next_keymap();
+
+private:
+    KeymapSwitcher();
+
+    Vector<AK::String> m_keymaps;
+
+    void setkeymap(AK::String const&);
+    String get_current_keymap() const;
+};
+
+}

Userland/Services/WindowServer/WindowManager.cpp

@@ -36,6 +36,7 @@ WindowManager& WindowManager::the()
 
 WindowManager::WindowManager(Gfx::PaletteImpl const& palette)
     : m_switcher(WindowSwitcher::construct())
+    , m_keymap_switcher(KeymapSwitcher::construct())
     , m_palette(palette)
 {
     s_the = this;
@@ -1557,6 +1558,11 @@ void WindowManager::process_key_event(KeyEvent& event)
         return;
     }
 
+    if (event.type() == Event::KeyDown && (event.modifiers() == (Mod_Alt | Mod_Shift) && (event.key() == Key_Shift || event.key() == Key_Alt))) {
+        m_keymap_switcher->next_keymap();
+        return;
+    }
+
     if (event.type() == Event::KeyDown && (event.modifiers() == (Mod_Ctrl | Mod_Alt) || event.modifiers() == (Mod_Ctrl | Mod_Shift | Mod_Alt)) && (window_stack_columns() > 1 || window_stack_rows() > 1)) {
         auto& current_stack = current_window_stack();
         auto row = current_stack.row();

Userland/Services/WindowServer/WindowManager.h

@@ -19,6 +19,7 @@
 #include <LibGfx/Rect.h>
 #include <WindowServer/Cursor.h>
 #include <WindowServer/Event.h>
+#include <WindowServer/KeymapSwitcher.h>
 #include <WindowServer/MenuManager.h>
 #include <WindowServer/ScreenLayout.h>
 #include <WindowServer/WMClientConnection.h>
@@ -433,6 +434,7 @@ private:
     u8 m_keyboard_modifiers { 0 };
 
     NonnullRefPtr<WindowSwitcher> m_switcher;
+    NonnullRefPtr<KeymapSwitcher> m_keymap_switcher;
 
     WeakPtr<Button> m_cursor_tracking_button;
     WeakPtr<Button> m_hovered_button;

Userland/Services/WindowServer/main.cpp

@@ -21,17 +21,19 @@
 
 ErrorOr<int> serenity_main(Main::Arguments)
 {
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc sigaction"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc sigaction exec"));
     TRY(Core::System::unveil("/res", "r"));
     TRY(Core::System::unveil("/tmp", "cw"));
     TRY(Core::System::unveil("/etc/WindowServer.ini", "rwc"));
     TRY(Core::System::unveil("/dev", "rw"));
+    TRY(Core::System::unveil("/bin/keymap", "x"));
+    TRY(Core::System::unveil("/proc/keymap", "r"));
 
     struct sigaction act = {};
     act.sa_flags = SA_NOCLDWAIT;
     act.sa_handler = SIG_IGN;
     TRY(Core::System::sigaction(SIGCHLD, &act, nullptr));
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc exec"));
 
     auto wm_config = Core::ConfigFile::open("/etc/WindowServer.ini");
     auto theme_name = wm_config->read_entry("Theme", "Name", "Default");
@@ -49,7 +51,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
 
     WindowServer::EventLoop loop;
 
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath proc"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath proc exec"));
 
     // First check which screens are explicitly configured
     {