[PATCH v2] ui/gtk: Handle empty notebook state in menu handlers

[dongwon.kim@intel.com]

From: Dongwon Kim <dongwon.kim@intel.com>

When all virtual console tabs are detached (untabified) from the main
window, the notebook contains no active pages, causing
gtk_notebook_get_current_page() to return -1.

Because gtk_notebook_page_num() also returns -1 for any detached VC,
gd_vc_find_by_page(s, -1) mistakenly matches the first detached
console. As a result, gd_vc_find_current() incorrectly returns
a detached VC instead of NULL. Menu actions executed on the empty main
window then unintentionally operate on that detached VC.

Fix this by having gd_vc_find_current() explicitly check for page < 0
and return NULL when the notebook has no active page. In addition, add
NULL checks for the current VC across relevant UI menu callbacks so
actions are properly bypassed or reset when no console tab is focused
in the main window.

Cc: Daniel P. Berrangé <berrange@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
 ui/gtk.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/ui/gtk.c b/ui/gtk.c
index 7078d89d67..0b5139ef31 100644
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -184,6 +184,11 @@ static VirtualConsole *gd_vc_find_current(GtkDisplayState *s)
     gint page;
 
     page = gtk_notebook_get_current_page(GTK_NOTEBOOK(s->notebook));
+
+    if (page < 0) {
+        return NULL;
+    }
+
     return gd_vc_find_by_page(s, page);
 }
 
@@ -1462,7 +1467,10 @@ static void gd_menu_show_tabs(GtkMenuItem *item, void *opaque)
     } else {
         gtk_notebook_set_show_tabs(GTK_NOTEBOOK(s->notebook), FALSE);
     }
-    gd_update_windowsize(vc);
+
+    if (vc) {
+        gd_update_windowsize(vc);
+    }
 }
 
 static int gd_vc_notebook_pos(GtkDisplayState *s, VirtualConsole *target)
@@ -1535,6 +1543,10 @@ static void gd_menu_untabify(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
     if (vc->type == GD_VC_GFX &&
         qemu_console_is_graphic(vc->gfx.dcl.con)) {
         gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(s->grab_item),
@@ -1588,7 +1600,10 @@ static void gd_menu_show_menubar(GtkMenuItem *item, void *opaque)
     } else {
         gtk_widget_hide(s->menu_bar);
     }
-    gd_update_windowsize(vc);
+
+    if (vc) {
+        gd_update_windowsize(vc);
+    }
 }
 
 static void gd_accel_show_menubar(void *opaque)
@@ -1605,7 +1620,7 @@ static void gd_menu_full_screen(GtkMenuItem *item, void *opaque)
     if (!s->full_screen) {
         gtk_notebook_set_show_tabs(GTK_NOTEBOOK(s->notebook), FALSE);
         gtk_widget_hide(s->menu_bar);
-        if (vc->type == GD_VC_GFX) {
+        if (vc && vc->type == GD_VC_GFX) {
             gtk_widget_set_size_request(vc->gfx.drawing_area, -1, -1);
         }
         gtk_window_fullscreen(GTK_WINDOW(s->window));
@@ -1618,14 +1633,16 @@ static void gd_menu_full_screen(GtkMenuItem *item, void *opaque)
             gtk_widget_show(s->menu_bar);
         }
         s->full_screen = FALSE;
-        if (vc->type == GD_VC_GFX) {
+        if (vc && vc->type == GD_VC_GFX) {
             vc->gfx.scale_x = vc->gfx.preferred_scale;
             vc->gfx.scale_y = vc->gfx.preferred_scale;
             gd_update_windowsize(vc);
         }
     }
 
-    gd_update_cursor(vc);
+    if (vc) {
+        gd_update_cursor(vc);
+    }
 }
 
 static void gd_accel_full_screen(void *opaque)
@@ -1639,6 +1656,10 @@ static void gd_menu_zoom_in(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
     gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(s->zoom_fit_item),
                                    FALSE);
 
@@ -1659,6 +1680,10 @@ static void gd_menu_zoom_out(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
     gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(s->zoom_fit_item),
                                    FALSE);
 
@@ -1676,6 +1701,10 @@ static void gd_menu_zoom_fixed(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
     vc->gfx.scale_x = vc->gfx.preferred_scale;
     vc->gfx.scale_y = vc->gfx.preferred_scale;
 
@@ -1687,6 +1716,10 @@ static void gd_menu_zoom_fit(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
     if (gtk_check_menu_item_get_active(GTK_CHECK_MENU_ITEM(s->zoom_fit_item))) {
         s->free_scale = TRUE;
     } else {
@@ -1800,6 +1833,11 @@ static void gd_menu_grab_input(GtkMenuItem *item, void *opaque)
     VirtualConsole *vc = gd_vc_find_current(s);
 
     if (gd_is_grab_active(s)) {
+        if (!vc) {
+            gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(s->grab_item),
+                                           FALSE);
+            return;
+        }
         gd_grab_keyboard(vc, "user-request-main-window");
         gd_grab_pointer(vc, "user-request-main-window");
     } else {
@@ -1807,7 +1845,9 @@ static void gd_menu_grab_input(GtkMenuItem *item, void *opaque)
         gd_ungrab_pointer(s);
     }
 
-    gd_update_cursor(vc);
+    if (vc) {
+        gd_update_cursor(vc);
+    }
 }
 
 static void gd_change_page(GtkNotebook *nb, gpointer arg1, guint arg2,
@@ -1983,6 +2023,10 @@ static void gd_menu_copy(GtkMenuItem *item, void *opaque)
     GtkDisplayState *s = opaque;
     VirtualConsole *vc = gd_vc_find_current(s);
 
+    if (!vc) {
+        return;
+    }
+
 #if VTE_CHECK_VERSION(0, 50, 0)
     vte_terminal_copy_clipboard_format(VTE_TERMINAL(vc->vte.terminal),
                                        VTE_FORMAT_TEXT);
-- 
2.43.0