WindowManager: Basic support for system keymap switching

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));
+    }
+}
+
+}