+ /*
+ * Make sure the ex_data stack is at least |mx| elements long to avoid
+ * issues in the for loop that follows; so go get the |mx|'th element
+ * (if it does not exist CRYPTO_get_ex_data() returns NULL), and assign
+ * to itself. This is normally a no-op; but ensures the stack is the
+ * proper size
+ */
+ if (!CRYPTO_set_ex_data(to, mx - 1, CRYPTO_get_ex_data(to, mx - 1)))
+ goto err;