Fix std* files not being redirected when daemonising

This could occur when built with assertions removed.

Closes #2708. Thanks to ckoehne.

ChangeLog.txt

@@ -3,6 +3,8 @@ Broker:
  disappearing.
 - Fix some retained topic memory not being cleared immediately after used.
 - Fix error handling related to the `bind_interface` option.
+- Fix std* files not being redirected when daemonising, when built with
+ assertions removed. Closes #2708.
 
 2.0.15 - 2022-08-16
 ===================

src/mosquitto.c

@@ -160,9 +160,18 @@ static void mosquitto__daemonise(void)
  exit(1);
  }
 
- assert(freopen("/dev/null", "r", stdin));
- assert(freopen("/dev/null", "w", stdout));
- assert(freopen("/dev/null", "w", stderr));
+ if(!freopen("/dev/null", "r", stdin)){
+ log__printf(NULL, MOSQ_LOG_ERR, "Error whilst daemonising (%s): %s", "stdin", strerror(errno));
+ exit(1);
+ }
+ if(!freopen("/dev/null", "w", stdout)){
+ log__printf(NULL, MOSQ_LOG_ERR, "Error whilst daemonising (%s): %s", "stdout", strerror(errno));
+ exit(1);
+ }
+ if(!freopen("/dev/null", "w", stderr)){
+ log__printf(NULL, MOSQ_LOG_ERR, "Error whilst daemonising (%s): %s", "stderr", strerror(errno));
+ exit(1);
+ }
 #else
  log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Can't start in daemon mode in Windows.");
 #endif