[gegl] seamless-clone: strdup error_msg to avoid freeing the empty string ""

[Massimo Valentini <mvalentini src gnome org>]

commit 39ea58f07e26f0c1940d4e8ee0a8b5e12444476b
Author: Massimo Valentini <mvalentini src gnome org>
Date:   Fri May 17 18:29:30 2013 +0200

    seamless-clone: strdup error_msg to avoid freeing the empty string ""

 operations/seamless-clone/seamless-clone.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/operations/seamless-clone/seamless-clone.c b/operations/seamless-clone/seamless-clone.c
index 9fec9f1..1c9d35e 100644
--- a/operations/seamless-clone/seamless-clone.c
+++ b/operations/seamless-clone/seamless-clone.c
@@ -143,6 +143,7 @@ process (GeglOperation       *operation,
   g_mutex_lock (&props->mutex);
   if (props->first_processing)
     {
+      const gchar *error_msg = "";
       if (props->context == NULL)
         {
           props->context = gegl_sc_context_new (aux, gegl_operation_source_get_bounding_box (operation, 
"aux"), 0.5, &error);
@@ -154,17 +155,16 @@ process (GeglOperation       *operation,
       switch (error)
         {
           case GEGL_SC_CREATION_ERROR_NONE:
-            o->error_msg = "";
             props->is_valid = TRUE;
             break;
           case GEGL_SC_CREATION_ERROR_EMPTY:
-            o->error_msg = _("The foreground does not contain opaque parts");
+            error_msg = _("The foreground does not contain opaque parts");
             break;
           case GEGL_SC_CREATION_ERROR_TOO_SMALL:
-            o->error_msg = _("The foreground is too small to use");
+            error_msg = _("The foreground is too small to use");
             break;
           case GEGL_SC_CREATION_ERROR_HOLED_OR_SPLIT:
-            o->error_msg = _("The foreground contains holes and/or several unconnected parts");
+            error_msg = _("The foreground contains holes and/or several unconnected parts");
             break;
           default:
             g_warning ("Unknown preprocessing status %d", error);
@@ -175,11 +175,14 @@ process (GeglOperation       *operation,
         {
           if (! gegl_sc_context_prepare_render (props->context, &info))
             {
-              o->error_msg = _("The opaque parts of the foreground are not above the background!");
+              error_msg = _("The opaque parts of the foreground are not above the background!");
               props->is_valid = FALSE;
             }
         }
 
+      g_free (o->error_msg);
+      o->error_msg = g_strdup (error_msg);
+
       props->first_processing = FALSE;
     }
   g_mutex_unlock (&props->mutex);