[evolution/gnome-3-38] EWebKitEditor: Prevent NULL dereference on call to WebKitWebView methods

[Milan Crha <mcrha src gnome org>]

commit df28542520f255d7990304ecadc602d7530165e4
Author: Milan Crha <mcrha redhat com>
Date:   Tue Sep 22 18:41:58 2020 +0200

    EWebKitEditor: Prevent NULL dereference on call to WebKitWebView methods
    
    The parent class may not have defined a method, which EWebKitEditor
    expects to have defined (and assigned), thus check for the existence
    and call it only if it's set.
    
    Related to https://bugs.webkit.org/show_bug.cgi?id=216828

 src/modules/webkit-editor/e-webkit-editor.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/src/modules/webkit-editor/e-webkit-editor.c b/src/modules/webkit-editor/e-webkit-editor.c
index d6fef27358..aa4a9aa129 100644
--- a/src/modules/webkit-editor/e-webkit-editor.c
+++ b/src/modules/webkit-editor/e-webkit-editor.c
@@ -5079,11 +5079,12 @@ webkit_editor_drag_data_received_cb (GtkWidget *widget,
            info == E_DND_TARGET_TYPE_UTF8_STRING || info == E_DND_TARGET_TYPE_STRING ||
            info == E_DND_TARGET_TYPE_TEXT_PLAIN || info == E_DND_TARGET_TYPE_TEXT_PLAIN_UTF8) {
                gdk_drag_status (context, gdk_drag_context_get_selected_action(context), time);
-               if (!GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_drop (widget, context, x, y, 
time)) {
-                       g_warning ("Drop failed in WebKit");
+               if (!GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_drop ||
+                   !GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_drop (widget, context, x, y, 
time)) {
                        goto process_ourselves;
                } else {
-                       GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_leave(widget, context, time);
+                       if (GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_leave)
+                               GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_leave (widget, context, 
time);
                        g_signal_stop_emission_by_name (widget, "drag-data-received");
                        e_content_editor_emit_drop_handled (E_CONTENT_EDITOR (widget));
                }
@@ -5318,7 +5319,8 @@ webkit_editor_button_press_event (GtkWidget *widget,
        }
 
        /* Chain up to parent's button_press_event() method. */
-       return GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->button_press_event (widget, event);
+       return GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->button_press_event &&
+              GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->button_press_event (widget, event);
 }
 
 static gboolean
@@ -5391,7 +5393,8 @@ webkit_editor_key_press_event (GtkWidget *widget,
                return FALSE;
 
        /* Chain up to parent's key_press_event() method. */
-       return GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->key_press_event (widget, event);
+       return GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->key_press_event &&
+              GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->key_press_event (widget, event);
 }
 
 static void