Registering a Signal Handler

A signal handler can be registered using

• sighandler_t signal(int signum, sighandler_t handler);

     The handler has the following prototype : 

     void handler(int signum)

• int sigaction(int signum, const struct sigaction *act, struct sigaction *oldact); 

    -> The sigaction structure contains the reference to the handler.
    -> The handler can have two different prototypes.

       void handler(int signum)

       void handler(int signum, siginfo_t *info, void *data)

Inside the handler code, only some functions can be used : only

the asyncsignalsafe functions, as documented by signal(7).

See an example below how to use the above api's.

#include <signal.h>

#include <assert.h>

#include <unistd.h>

#include <stdio.h>

void myhandler(int signum) {

   printf("Signal catched!\n");

}

int main(void) {

   int ret;

   struct sigaction action = {

      .sa_handler = myhandler,

   };

   ret = sigaction(SIGUSR1, & action, NULL);

   assert(ret == 0);

   while(1);

   return 0;

}