SPAWN SERVER: close all open fds on callback (netdata#18764)

close all open fds on callback

src/libnetdata/spawn_server/spawn_server_nofork.c

@@ -57,6 +57,9 @@ static void spawn_server_run_child(SPAWN_SERVER *server, SPAWN_REQUEST *rq) {
     if(server->pipe[0] != -1) { close(server->pipe[0]); server->pipe[0] = -1; }
     if(server->pipe[1] != -1) { close(server->pipe[1]); server->pipe[1] = -1; }
 
+    // close all open file descriptors of the parent, but keep ours
+    os_close_all_non_std_open_fds_except(rq->fds, 4, 0);
+
     // set the process name
     os_setproctitle("spawn-child", server->argc, server->argv);
 
@@ -351,8 +354,6 @@ static bool spawn_server_run_callback(SPAWN_SERVER *server __maybe_unused, SPAWN
     }
 
     pid_t pid = fork();
-    gettid_uncached(); // make sure the logger logs valid pids
-
     if (pid < 0) {
         // fork failed
 
@@ -362,6 +363,7 @@ static bool spawn_server_run_callback(SPAWN_SERVER *server __maybe_unused, SPAWN
     else if (pid == 0) {
         // the child
 
+        gettid_uncached(); // make sure the logger logs valid pids
         spawn_server_run_child(server, rq);
         exit(63);
     }
@@ -1068,6 +1070,7 @@ SPAWN_SERVER* spawn_server_create(SPAWN_SERVER_OPTIONS options, const char *name
     pid_t pid = fork();
     if (pid == 0) {
         // the child - the spawn server
+        gettid_uncached(); // make sure the logger logs valid pids
 
         {
             char buf[15];