gdkkeys-win32: Fix crash when keyboard DLL failed to load

DLL loading failures should not happen under normal circumstances, but
we should at least try not to crash and and print better diagnostic
messages if they do happen.

See https://gitlab.gnome.org/GNOME/gtk/-/issues/4610

gdk/win32/gdkkeys-win32-impl.c

@@ -180,7 +180,8 @@ keystate_to_modbits (GdkWin32KeymapLayoutInfo *info,
   BYTE       result = 0;
   int        i;
 
-  g_return_val_if_fail (tables != NULL, 0);
+  if (tables == NULL)
+    return 0;
 
   vk_to_bit = tables->pCharModifiers.ptr->pVkToBit.ptr;
 
@@ -198,7 +199,8 @@ modbits_to_level (GdkWin32KeymapLayoutInfo *info,
   PKBDTABLES tables = (PKBDTABLES) info->tables;
   PMODIFIERS modifiers;
 
-  g_return_val_if_fail (tables != NULL, 0);
+  if (tables == NULL)
+    return 0;
 
   modifiers = tables->pCharModifiers.ptr;
   if (modbits > modifiers->wMaxModBits)
@@ -268,7 +270,8 @@ vk_to_char_fuzzy (GdkWin32KeymapLayoutInfo *info,
   if (is_dead)
     *is_dead = FALSE;
 
-  g_return_val_if_fail (tables != NULL, WCH_NONE);
+  if (tables == NULL)
+    return WCH_NONE;
 
   wch_tables = tables->pVkToWcharTable.ptr;
 

gdk/win32/gdkkeys-win32.c

@@ -181,6 +181,7 @@ get_keyboard_layout_file (const char *layout_name)
   DWORD  file_name_len = 0;
   int    dir_len       = 0;
   int    buf_len       = 0;
+  LSTATUS status;
 
   static const char prefix[] = "SYSTEM\\CurrentControlSet\\Control\\"
                                "Keyboard Layouts\\";
@@ -189,18 +190,32 @@ get_keyboard_layout_file (const char *layout_name)
   g_snprintf (kbdKeyPath, sizeof (prefix) + KL_NAMELENGTH, "%s%s", prefix,
               layout_name);
 
-  if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, (LPCSTR) kbdKeyPath, 0,
+
-                     KEY_QUERY_VALUE, &hkey) != ERROR_SUCCESS)
+  status = RegOpenKeyExA (HKEY_LOCAL_MACHINE, (LPCSTR) kbdKeyPath, 0,
-    goto fail1;
+                          KEY_QUERY_VALUE, &hkey);
+  if (status != ERROR_SUCCESS)
+    {
+      g_warning("Could not open registry key '%s'. Error code: %d",
+                kbdKeyPath, (int)status);
+      goto fail1;
+    }
 
   /* Get sizes */
-  if (RegQueryValueExA (hkey, "Layout File", 0, &var_type, 0,
+  status = RegQueryValueExA (hkey, "Layout File", 0, &var_type, 0,
-			&file_name_len) != ERROR_SUCCESS)
+                             &file_name_len);
-    goto fail2;
+  if (status != ERROR_SUCCESS)
+    {
+      g_warning("Could not query registry key '%s\\Layout File'. Error code: %d",
+                kbdKeyPath, (int)status);
+      goto fail2;
+    }
 
   dir_len = GetSystemDirectoryA (0, 0); /* includes \0 */
   if (dir_len == 0)
-    goto fail2;
+    {
+      g_warning("GetSystemDirectoryA failed. Error: %d", (int)GetLastError());
+      goto fail2;
+    }
 
   /* Allocate buffer */
   buf_len = dir_len + (int) strlen ("\\") + file_name_len;
@@ -214,10 +229,12 @@ get_keyboard_layout_file (const char *layout_name)
   result[dir_len - 1] = '\\';
 
   /* Append file name */
-  if (RegQueryValueExA (hkey, "Layout File", 0, &var_type,
+  status = RegQueryValueExA (hkey, "Layout File", 0, &var_type,
-			(LPBYTE) &result[dir_len], &file_name_len)
+                             (LPBYTE) &result[dir_len], &file_name_len);
-      != ERROR_SUCCESS)
+  if (status != ERROR_SUCCESS)
-    goto fail3;
+    {
+      goto fail3;
+    }
 
   result[dir_len + file_name_len] = '\0';
 
@@ -415,6 +432,9 @@ gdk_keysym_to_key_entry_index (GdkWin32KeymapLayoutInfo *info,
   gunichar c;
   gintptr  index;
 
+  if (info->reverse_lookup_table == NULL)
+    return -1;
+
   /* Special cases */
   if (sym == GDK_KEY_Tab)
     return VK_TAB;
@@ -439,8 +459,6 @@ gdk_keysym_to_key_entry_index (GdkWin32KeymapLayoutInfo *info,
   /* Try converting to Unicode and back */
   c = gdk_keyval_to_unicode (sym);
 
-  g_return_val_if_fail (info->reverse_lookup_table != NULL, -1);
-
   index = -1;
   if (g_hash_table_lookup_extended (info->reverse_lookup_table,
                                     GINT_TO_POINTER (c),
@@ -537,7 +555,7 @@ update_keymap (GdkWin32Keymap *keymap)
 
           info->file = get_keyboard_layout_file (info->name);
 
-          if (load_layout_dll (keymap, info->file, info))
+          if (info->file != NULL && load_layout_dll (keymap, info->file, info))
             {
               info->key_entries = g_array_new (FALSE, FALSE,
                                                sizeof (GdkWin32KeymapKeyEntry));
@@ -546,6 +564,11 @@ update_keymap (GdkWin32Keymap *keymap)
                                                              g_direct_equal);
               init_vk_lookup_table (keymap, info);
             }
+          else
+            {
+              g_warning("Failed to load keyboard layout DLL for layout %s: %s",
+                        info->name, info->file);
+            }
         }
 
       if (info->handle == current_layout)
@@ -978,6 +1001,13 @@ gdk_win32_keymap_translate_keyboard_state (GdkKeymap       *gdk_keymap,
   if (consumed_modifiers)
     *consumed_modifiers = mod_bits_to_gdk_mod_mask (consumed_mod_bits);
 
+  /* Just a diagnostic message to inform the user why their keypresses aren't working.
+   * Shouldn't happen under normal circumstances. */
+  if (tmp_keyval == GDK_KEY_VoidSymbol && layout_info->tables == NULL)
+    g_warning("Failed to translate keypress (keycode: %u) for group %d (%s) because "
+              "we could not load the layout.",
+              hardware_keycode, group, layout_info->name);
+
   return tmp_keyval != GDK_KEY_VoidSymbol;
 }