CA-407106: Avoid using deprecated sigset and sigignore functions

Use `sigaction` and `sigprocmask` instead.
There is also `signal`, but the manpage says to not use it.
Indeed `sigaction` has more reliable semantics by default in POSIX (e.g. it blocks the signal while you are handling it,
so you don't reenter it while it is executing).

Unfortunately the new functions are more verbose, so introduce a loop for setting up the signal handlers.

Signed-off-by: Edwin Török <[email protected]>

daemon/main.c

@@ -219,7 +219,9 @@ main(
     //  logrotate may send SIGHUP regardless of the state of xha. 
     //
 
-    sigignore(SIGHUP);
+    struct sigaction ignore = { 0 };
+    ignore.sa_handler = SIG_IGN;
+    sigaction(SIGHUP, &ignore, NULL);
 
     //  Initialize ha_config in BSS.
     //  (static initialization causes a warning for unknown reason)
@@ -315,7 +317,7 @@ main(
 
     for (sig = 1; sig < _NSIG; sig++)
     {
-        sigignore(sig);
+        sigaction(sig, &ignore, NULL);
     }
 
     //  #### Set resource limit of core size to max value
@@ -420,18 +422,19 @@ main(
 //
 //  sigcatch -
 //
-//  signal handler for sigset().
+//  signal handler for sigaction().
 //
 //  sigcatch may be invoked in any thread context in any time.
 //  Acquiring any lock which does not support recursive in this function causes deadlock.
 //
+//  action.sa_flags is 0, which means that the signal that triggerred the handler
+//  is automatically blocked already
+//
 
 MTC_STATIC void
 sigcatch(
     int signo)
 {
-    sigset(signo, sigcatch);
-
     switch (signo)
     {
     case SIGTERM:
@@ -491,10 +494,21 @@ post_phase_init(
         }
 
         //  Now it's time to catch signals.
+        static const int signals[] = { SIGTERM, SIGCHLD, SIGHUP };
+        sigset_t mask;
+        unsigned i;
+        struct sigaction action = { 0 };
+        action.sa_handler = sigcatch;
+        sigemptyset(&mask);
+
+        for (i = 0; i < sizeof(signals) / sizeof(signals[0]); i++) {
+            int sig = signals[i];
+            sigaddset(&mask, sig);
+
+            sigaction(sig, &action, NULL);
+        }
 
-        sigset(SIGTERM, sigcatch);
-        sigset(SIGCHLD, sigcatch);
-        sigset(SIGHUP, sigcatch);
+        sigprocmask(SIG_UNBLOCK, &mask, NULL);
     }
 }