+ /*
+ * Need to check that source and destination sizes are
+ * filled in before comparing them.
+ *
+ * If we already have "cnt_data" filled in, we know it's
+ * all good (avoid checking the size for zero, as that
+ * is a possible size - we really should have a flag to
+ * say whether the size is valid or not!)
+ */
+ if (!src->cnt_data && diff_populate_filespec(src, 0))
+ return 0;
+ if (!dst->cnt_data && diff_populate_filespec(dst, 0))
+ return 0;
+