kernel: Allow turning off the TTY by setting it to graphical mode

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -11,6 +11,7 @@
 #include <luna/Vector.h>
 
 Vector<SharedPtr<ConsoleDevice>> ConsoleDevice::m_console_devices;
+bool ConsoleDevice::s_is_in_graphical_mode { false };
 
 Result<void> ConsoleDevice::create()
 {
@@ -60,6 +61,8 @@ Result<usize> ConsoleDevice::write(const u8* buf, usize, usize length)
 {
     if (m_settings.c_lflag & TOSTOP) TRY(handle_background_process_group(true, SIGTTOU));
 
+    if (s_is_in_graphical_mode) return length;
+
     TextConsole::write((const char*)buf, length);
     return length;
 }
@@ -229,6 +232,10 @@ Result<u64> ConsoleDevice::ioctl(int request, void* arg)
         if (!MemoryManager::copy_to_user_typed((struct winsize*)arg, &window)) return err(EFAULT);
         return 0;
     }
+    case TTYSETGFX: {
+        s_is_in_graphical_mode = (bool)arg;
+        return 0;
+    }
     default: return err(EINVAL);
     }
 }

kernel/src/fs/devices/ConsoleDevice.h

@@ -40,6 +40,7 @@ class ConsoleDevice : public Device
     mutable Keyboard::KeyboardState m_kb_state;
 
     static Vector<SharedPtr<ConsoleDevice>> m_console_devices;
+    static bool s_is_in_graphical_mode;
 
     void process_key_event(u8 scancode);
 

libc/include/bits/ioctl-defs.h

@@ -8,4 +8,7 @@
 #define FB_GET_HEIGHT 1
 #define FB_GET_SCANLINE 2
 
+/* TTY requests. */
+#define TTYSETGFX 162
+
 #endif