[gtk] imwayland: fix potential leak of attr list

[Christian Hergert <chergert src gnome org>]

commit 002e48c469be2a4506153f692124631d3f3cf13a
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jul 28 10:37:21 2018 -0700

    imwayland: fix potential leak of attr list
    
    This fixes a potential leak of a PangoAttrList that is set when chaining
    up to the parent get_preedit_string(). We check to see if the attr list
    was created and reuse it instead of leaking the previous value.

 gtk/gtkimcontextwayland.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkimcontextwayland.c b/gtk/gtkimcontextwayland.c
index 141ad6c6c9..07d9628915 100644
--- a/gtk/gtkimcontextwayland.c
+++ b/gtk/gtkimcontextwayland.c
@@ -469,6 +469,9 @@ gtk_im_context_wayland_get_preedit_string (GtkIMContext   *context,
   GtkIMContextWayland *context_wayland = GTK_IM_CONTEXT_WAYLAND (context);
   const char *preedit_str;
 
+  if (attrs)
+    *attrs = NULL;
+
   GTK_IM_CONTEXT_CLASS (gtk_im_context_wayland_parent_class)->get_preedit_string (context, str, attrs, 
cursor_pos);
 
   /* If the parent implementation returns a len>0 string, go with it */
@@ -490,7 +493,8 @@ gtk_im_context_wayland_get_preedit_string (GtkIMContext   *context,
 
   if (attrs)
     {
-      *attrs = pango_attr_list_new ();
+      if (!*attrs)
+        *attrs = pango_attr_list_new ();
       pango_attr_list_insert (*attrs,
                               pango_attr_underline_new (PANGO_UNDERLINE_SINGLE));
     }