configure: Stop avoiding -Wformat-zero-length.

Debian likes to enable -Wformat-zero-length, even over our code trying to
disable it.  It isn't too hard to make our code warning-free against this
option, so this commit both stops disabling it and fixes the warnings.

The first fix is to change set_subprogram_name() to take a plain string
instead of a format string, and to adjust its few callers.  This fixes one
warning since one of those callers passed in an empty string.

The second fix is to remove a test for ovs_scan() against an empty string.
I couldn't find a way to avoid a warning for this test, and it isn't too
valuable in any case.

This allows us to drop filtering for -Wformat from the Debian rules file,
so this commit removes it.

Signed-off-by: Ben Pfaff <blp@nicira.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index b2d05a6cb..88b92d1d7 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2014 Nicira, Inc.
+ * Copyright (c) 2013, 2014, 2015 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -332,7 +332,9 @@ ovsthread_wrapper(void *aux_)
 
     /* The order of the following calls is important, because
      * ovsrcu_quiesce_end() saves a copy of the thread name. */
-    set_subprogram_name("%s%u", aux.name, id);
+    char *subprogram_name = xasprintf("%s%u", aux.name, id);
+    set_subprogram_name(subprogram_name);
+    free(subprogram_name);
     ovsrcu_quiesce_end();
 
     return aux.start(aux.arg);