//...
static int FD_set[MAX_FD], FD_q[MAX_FD];
// Static structures here to not make malloc at all :)
static int pos = 1;
static int sig;

void Handler(int sig, siginfo_t *si, void *whatisthis) {
    // work like Edge Triggered
    if (FD_set[si->si_fd]) {;
        return;
    }
    FD_set[si->si_fd] = pos;
    FD_q[pos] = si->si_fd;
    pos++;
}

MODULE = RtSig          PACKAGE = RtSig

int
SetSigaction(arg)
       int     arg
   CODE:
        struct  sigaction  act;
        sig = arg;
        act.sa_flags = SA_SIGINFO|SA_RESTART;
        act.sa_sigaction = Handler;
        sigfillset(&act.sa_mask);
        if (sigaction(sig, &act, 0) == 0) {
            RETVAL = 1;
        } else {
            XSRETURN_UNDEF;
        }
   OUTPUT:
       RETVAL

void
Poll()
   INIT:
       int i;
       sigset_t mask, old_mask;
   PPCODE:
       sigemptyset(&mask);
       sigaddset(&mask, sig);
       sigprocmask(SIG_BLOCK, &mask, &old_mask);
       for (i=1; i < pos; i++) {
           XPUSHs(sv_2mortal(newSVnv(FD_q[i])));
           FD_set[FD_q[i]] = 0;
           FD_q[i] = 0;
       }
       pos = 1;
       sigprocmask(SIG_SETMASK, &old_mask, 0);