Pool cleanups are not called in the daemonization

[spacewanderlzx@…]

When we run our testsuites with LeakSanitizer, we noticed lots of leak reports.

After some investigations, we found that the pool cleanups registered with ngx_cycle->pool are not invoked when the parent exits during the daemonization, which causes the leak reports.

I am not sure whether it is a bug, or should we change the testsuite to run Nginx in "daemon off" mode.
Anyway, it could be 'fixed' via a simple change:

--- a/src/os/unix/ngx_daemon.c
+++ b/src/os/unix/ngx_daemon.c
@@ -23,6 +23,7 @@ ngx_daemon(ngx_log_t *log)
         break;
 
     default:
+        ngx_destroy_pool(ngx_cycle->pool);
         exit(0);
     }

Note that this change doesn't cover signaller mode and error handling path.

[Maxim Dounin]

The ngx_daemon() function is not expected to free ngx_cycle or any other global variables - all these variables will be available in the new process, and exit() will free anything in the old process. The best solution here would be to configure LeakSanitizer to ignore these "leaks" as clearly these are false positives.