use static buffer for get_uptime_string call

src/http_microhttpd.c

@@ -995,9 +995,9 @@ static void replace_variables(
 	char maxclients[12];
 	char clientupload[20];
 	char clientdownload[20];
+	char uptime[64];
 
 	const char *redirect_url = NULL;
-	char *uptime = NULL;
 	char *denyaction = NULL;
 	char *authaction = NULL;
 	char *authtarget = NULL;
@@ -1007,7 +1007,7 @@ static void replace_variables(
 	sprintf(clientupload, "%llu", client->counters.outgoing);
 	sprintf(clientdownload, "%llu", client->counters.incoming);
 
-	uptime = get_uptime_string();
+	get_uptime_string(uptime);
 	redirect_url = get_redirect_url(connection);
 
 	sprintf(nclients, "%d", get_client_list_length());
@@ -1043,7 +1043,6 @@ static void replace_variables(
 
 	tmpl_parse(vars, dst, dst_len, src, src_len);
 
-	free(uptime);
 	free(denyaction);
 	free(authaction);
 	free(authtarget);

src/util.c

@@ -367,11 +367,9 @@ format_time(time_t time, char buf[64])
 	return buf;
 }
 
-/* Caller must free. */
 char *
-get_uptime_string()
+get_uptime_string(char buf[64])
 {
-	char *buf = malloc(64);
 	return format_duration(started_time, time(NULL), buf);
 }
 

src/util.h

@@ -62,7 +62,7 @@ char *format_time(time_t time, char buf[64]);
 /*
  * @brief Mallocs and returns nodogsplash uptime string
  */
-char *get_uptime_string();
+char *get_uptime_string(char buf[64]);
 /*
  * @brief Writes a human-readable paragraph of the status of the nodogsplash process
  */