[gnome-photos] item-manager: Handle untrusted cursors when looking for a collection

[Debarshi Ray <debarshir src gnome org>]

commit 677ae108dd00d764b0393248a64ef9362101be49
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Feb 6 23:58:59 2018 +0100

    item-manager: Handle untrusted cursors when looking for a collection
    
    A subsequent commit will use PHOTOS_QUERY_FLAGS_UNFILTERED to check
    for URN changes caused by atomic file updates. This will lead to a
    more relaxed query, so it's wise to watch out for a NULL RDF type.

 src/photos-item-manager.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/src/photos-item-manager.c b/src/photos-item-manager.c
index 629add94..1fab4770 100644
--- a/src/photos-item-manager.c
+++ b/src/photos-item-manager.c
@@ -186,11 +186,16 @@ photos_item_manager_can_add_item_for_mode (PhotosItemManager *self, PhotosBaseIt
 static gboolean
 photos_item_manager_cursor_is_collection (TrackerSparqlCursor *cursor)
 {
-  gboolean ret_val;
+  gboolean ret_val = FALSE;
   const gchar *rdf_type;
 
   rdf_type = tracker_sparql_cursor_get_string (cursor, PHOTOS_QUERY_COLUMNS_RDF_TYPE, NULL);
+  if (rdf_type == NULL)
+    goto out;
+
   ret_val = strstr (rdf_type, "nfo#DataContainer") != NULL;
+
+ out:
   return ret_val;
 }