ui/sdl: Fix handling of caps lock and num lock keys

Starting with SDL version 1.2.14, caps lock and num lock keys
will send a SDL_KEYUP when SDL_DISABLE_LOCK_KEYS=1 is set in
the environment.

The new code sets the environment unconditionally
(it won't harm old versions which do not know it).

The workaround for SDL_KEYUP is only compiled with old SDL versions.

A similar patch without handling of old SDL versions was already
published by Benjamin Drung for Ubuntu.

Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Benjamin Drung <benjamin.drung@gmail.com>
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

ui/sdl.c

@@ -388,12 +388,16 @@ static void sdl_process_key(SDL_KeyboardEvent *ev)
         else
             modifiers_state[keycode] = 1;
         break;
+#define QEMU_SDL_VERSION ((SDL_MAJOR_VERSION << 8) + SDL_MINOR_VERSION)
+#if QEMU_SDL_VERSION < 0x102 || QEMU_SDL_VERSION == 0x102 && SDL_PATCHLEVEL < 14
+        /* SDL versions before 1.2.14 don't support key up for caps/num lock. */
     case 0x45: /* num lock */
     case 0x3a: /* caps lock */
         /* SDL does not send the key up event, so we generate it */
         kbd_put_keycode(keycode);
         kbd_put_keycode(keycode | SCANCODE_UP);
         return;
+#endif
     }
 
     /* now send the key code */
@@ -831,6 +835,10 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)
         setenv("SDL_VIDEO_ALLOW_SCREENSAVER", "1", 0);
     }
 
+    /* Enable normal up/down events for Caps-Lock and Num-Lock keys.
+     * This requires SDL >= 1.2.14. */
+    setenv("SDL_DISABLE_LOCK_KEYS", "1", 1);
+
     flags = SDL_INIT_VIDEO | SDL_INIT_NOPARACHUTE;
     if (SDL_Init (flags)) {
         fprintf(stderr, "Could not initialize SDL(%s) - exiting\n",