vmon: suppress "(null)" name in snapshot filenames

When this code changed to use a local, potentially heap-allocated
name variable, it started producing "(null)" when no -n/--name
was supplied, that wasn't intended.

Just use a "" name when NULL, enabling bare date-derived snapshot
filenames.  This seems preferable since even if you supplied an
empty -n/--name you'd get a hyphen at the start of the name.  I
can see scenarios where you have unnamed files labeled by the
output dir instead.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/vmon.c b/src/vmon.c
index b8b6046..cc60c5c 100644
--- a/src/vmon.c
+++ b/src/vmon.c
@@ -752,7 +752,7 @@ static int vmon_snapshot(vmon_t *vmon)
 	strftime(start_str, sizeof(start_str), "%m.%d.%y-%T", start_time);
 	snprintf(path, sizeof(path), "%s/%s%s%s-%u.png",
 		vmon->output_dir,
-		name,
+		name ? name : "",
 		name ? "-" : "",
 		start_str,
 		vmon->n_snapshots++);