From 916423ef9585c7042730fdb17f55afc376565d32 Mon Sep 17 00:00:00 2001
From: Jacob Erlbeck <jerlbeck@sysmocom.de>
Date: Mon, 9 Nov 2015 10:52:19 +0100
Subject: stats: Fix name prefix handling

Currently the having an unset prefix leads to an abort() in the
statsd reporter due to an fprintf format string error. In addition
the prefix cannot be reset to its initial state (NULL) by using 'no
prefix', which just sets the prefix to the empty string, causing a
single leading dot to appear in front of the name.

This commit changes the implemenation to consistly use NULL for
the unset name prefix ('no prefix') and to handle this case correctly
in the statsd reporter.

Sponsored-by: On-Waves ehf
---
 src/stats.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/stats.c b/src/stats.c
index a0723702..fa56f50a 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -278,7 +278,8 @@ int osmo_stats_set_interval(int interval)
 int osmo_stats_reporter_set_name_prefix(struct osmo_stats_reporter *srep, const char *prefix)
 {
 	talloc_free(srep->name_prefix);
-	srep->name_prefix = prefix ? talloc_strdup(srep, prefix) : NULL;
+	srep->name_prefix = prefix && strlen(prefix) > 0 ?
+		talloc_strdup(srep, prefix) : NULL;
 
 	return update_srep_config(srep);
 }
@@ -468,18 +469,29 @@ static int osmo_stats_reporter_statsd_send(struct osmo_stats_reporter *srep,
 	int buf_size;
 	int nchars, rc = 0;
 	char *fmt = NULL;
+	char *prefix = srep->name_prefix;
 	int old_len = msgb_length(srep->buffer);
 
-	if (name1) {
-		if (index1 != 0)
-			fmt = "%1$s.%2$s.%6$u.%3$s:%4$d|%5$s";
-		else
-			fmt = "%1$s.%2$s.%3$s:%4$d|%5$s";
+	if (prefix) {
+		if (name1) {
+			if (index1 != 0)
+				fmt = "%1$s.%2$s.%6$u.%3$s:%4$d|%5$s";
+			else
+				fmt = "%1$s.%2$s.%3$s:%4$d|%5$s";
+		} else {
+			fmt = "%1$s.%2$0.0s%3$s:%4$d|%5$s";
+		}
 	} else {
-		fmt = "%1$s.%2$0.0s%3$s:%4$d|%5$s";
+		prefix = "";
+		if (name1) {
+			if (index1 != 0)
+				fmt = "%1$s%2$s.%6$u.%3$s:%4$d|%5$s";
+			else
+				fmt = "%1$s%2$s.%3$s:%4$d|%5$s";
+		} else {
+			fmt = "%1$s%2$0.0s%3$s:%4$d|%5$s";
+		}
 	}
-	if (!srep->name_prefix)
-		fmt += 5; /* skip prefix part */
 
 	if (srep->agg_enabled) {
 		if (msgb_length(srep->buffer) > 0 &&
@@ -493,7 +505,7 @@ static int osmo_stats_reporter_statsd_send(struct osmo_stats_reporter *srep,
 	buf_size = msgb_tailroom(srep->buffer);
 
 	nchars = snprintf(buf, buf_size, fmt,
-		srep->name_prefix, name1, name2,
+		prefix, name1, name2,
 		value, unit, index1);
 
 	if (nchars >= buf_size) {
@@ -508,7 +520,7 @@ static int osmo_stats_reporter_statsd_send(struct osmo_stats_reporter *srep,
 		buf_size = msgb_tailroom(srep->buffer);
 
 		nchars = snprintf(buf, buf_size, fmt,
-			srep->name_prefix, name1, name2,
+			prefix, name1, name2,
 			value, unit, index1);
 
 		if (nchars >= buf_size)
-- 
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