fpm: Improve the error message when FPM is running as root

Author: TimWolla

sapi/fpm/fpm/fpm_conf.c

@@ -859,7 +859,7 @@ static int fpm_conf_process_all_pools(void)
 
 		/* alert if user is not set; only if we are root and fpm is not running with --allow-to-run-as-root */
 		if (!wp->config->user && !geteuid() && !fpm_globals.run_as_root) {
-			zlog(ZLOG_ALERT, "[pool %s] user has not been defined", wp->config->name);
+			zlog(ZLOG_ALERT, "[pool %s] FPM is running as root and the user directive has not been specified, refusing to run for security reasons. Specify either a pool-specific user directive or pass the --allow-to-run-as-root flag.", wp->config->name);
 			return -1;
 		}