Avoid passing NULL pointer to printf(3) %s

OpenBSD issues syslog(3) warnings about these as they may hint at bugs:
	shairport-sync: vfprintf %s NULL in "metadata socket address is "%s" port %d."

Metadata listener socket is empty by default so use the existing `strnull`.

diff --git a/shairport.c b/shairport.c
index bded416524abae2322631251a09c956cb7327884..e5b679695bf9fae00ae13043c54e2d4710d559ea 100644 (file)
--- a/shairport.c
+++ b/shairport.c
@@ -2491,7 +2491,7 @@ int main(int argc, char **argv) {
 #ifdef CONFIG_METADATA
   debug(1, "metadata enabled is %d.", config.metadata_enabled);
   debug(1, "metadata pipename is \"%s\".", config.metadata_pipename);
-  debug(1, "metadata socket address is \"%s\" port %d.", config.metadata_sockaddr,
+  debug(1, "metadata socket address is \"%s\" port %d.", strnull(config.metadata_sockaddr),
         config.metadata_sockport);
   debug(1, "metadata socket packet size is \"%d\".", config.metadata_sockmsglength);
   debug(1, "get-coverart is %d.", config.get_coverart);