15. Using SA_SIGINFO for Extended Signal Information

SA_SIGINFO flag helps the user to get detailed information about the signal such as signal number, sending process id, and additional data.

#include <stdio.h>

#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
void handle_signal(int sig, siginfo_t *info, void *context)
{
    printf("Caught signal %d from process %d\n", sig, info->si_pid);
}
int main()
{
    struct sigaction sa;
    sa.sa_sigaction = handle_signal;
    sa.sa_flags = SA_SIGINFO;
    // Use sa_sigaction instead of sa_handler
    sigemptyset(&sa.sa_mask);
    // 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;
}

Here, the handle signal prints the information about the signal number and the process id of the process sending the signal.