#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>

void my_handler(int signum) {

    fprintf(stdout, "My handler text message\n");   
}

int main() {

    // Create a struct variable
    struct sigaction new_action, old_action;

    // Assign the handler for new_action
    new_action.sa_handler = my_handler;

    // Initialize the struct new_action with empty values
    sigemptyset(&new_action.sa_mask);

    // Define the behaviour of the sa_flags
    new_action.sa_flags = SA_RESTART;
    old_action.sa_flags = SA_RESTART;

    // Add signal SIGALRM to the new_action struct
    // sigaction( Signalnummer, neue maske, alte maske)
    sigaction(SIGALRM, &new_action, NULL);


    int myalarm = alarm(2);

    // To block the SIGALRM use the following 2 lines
    sigaddset(&old_action.sa_mask, SIGALRM);
    sigprocmask(SIG_BLOCK, &new_action.sa_mask, &old_action.sa_mask);

    while(myalarm == 0) {
        sigsuspend(&old_action.sa_mask);
    }
    sigprocmask(SIG_UNBLOCK, &new_action.sa_mask, NULL);
}