14. Blocking Signals During Handler Execution

Signals can be blocked while a signal handler is being executed by specifying them in the sa_mask field. This prevents the specified signals from being interrupted by the handler. For e.g.: -

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include<unistd.h>
void my_sigaction(int signum, siginfo_t *info, void *context)
{
    printf("Caught signal %d, sent by process %d\n", signum, info->si_pid);
}
int main()
{
    struct sigaction sa;
    sa.sa_sigaction = my_sigaction;
    sa.sa_flags = SA_SIGINFO;
    // Use sa_sigaction instead of sa_handler
    sigemptyset(&sa.sa_mask);
    sigaddset(&sa.sa_mask, SIGTERM);
    // Block SIGTERM while handling SIGINT
    // Set up the signal handler for SIGINT
    if (sigaction(SIGINT, &sa, NULL) == -1)
    {
        perror("sigaction");
        exit(EXIT_FAILURE);
    }
    // Loop indefinitely
    while (1)
    {
        printf("Running...\n");
        sleep(1);
    }
    return 0;
}