[libdazzle] file-transfer: add some runtime warnings

[Christian Hergert <chergert src gnome org>]

commit e3f03a8d0e03f9ee20719d1827ac621bf17e9d86
Author: Christian Hergert <chergert redhat com>
Date:   Sun Dec 3 04:01:33 2017 -0800

    file-transfer: add some runtime warnings

 src/files/dzl-file-transfer.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/src/files/dzl-file-transfer.c b/src/files/dzl-file-transfer.c
index fb5c1df..1c67ee8 100644
--- a/src/files/dzl-file-transfer.c
+++ b/src/files/dzl-file-transfer.c
@@ -201,6 +201,18 @@ dzl_file_transfer_add (DzlFileTransfer *self,
       DZL_EXIT;
     }
 
+  if (g_file_equal (src, dst))
+    {
+      g_warning ("Source and destination cannot be the same");
+      DZL_EXIT;
+    }
+
+  if (g_file_has_prefix (dst, src))
+    {
+      g_warning ("Destination cannot be within source");
+      DZL_EXIT;
+    }
+
   oper = g_slice_new0 (Oper);
   oper->src = g_object_ref (src);
   oper->dst = g_object_ref (dst);