Call function before shutdown the system

[bkpawar_linux]

I wrote the test code for blocking the shutdown for some time using the Signal handler.
But unable to catch the SIGTERM signal if I do shutdown, as man pages says shutdown genrates the SIGTERM and SIGKILL signals, but we cant handle the SIGKILL signal.

My code is working fine if I genrate the SIGTERM signal by Kill command, and also for
SIGINT signgal genrated from the CTRL+c key.

Thanks in advance for your ideas:

Here is my code:

/* Example of using sigaction() to setup a signal handler with 3 arguments
* including siginfo_t.
*/
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>

static void signal_hdl (int sig, siginfo_t *siginfo, void *context);
static void process_signal (void);

static void signal_hdl (int sig, siginfo_t *siginfo, void *context)
{
printf("Entering in singnal handler Caught the %d Signal Please wait\n",sig);
process_signal();
printf("Exiting from the signal handler\n");
}

static void process_signal (void)
{
int i, j, k;
/*Stay here for some time Do something*/
for (i = 0; i < 10000; i++)
{
for (j = 0; j < 100000; j++);
{
for (k = 0; k < 100000; k++);
}

}

return;
}

int main (int argc, char *argv[])
{
struct sigaction act, old_act;

memset (&act, '\0', sizeof(act));

/* Use the sa_sigaction field because the handles has two additional parameters */
act.sa_sigaction = &signal_hdl;

/* The SA_SIGINFO flag tells sigaction() to use the sa_sigaction field, not sa_handler. */
act.sa_flags = SA_SIGINFO;

if (sigaction(SIGTERM, &act, &old_act) < 0) {
perror ("sigaction failed for SIGTERM signal\n");
return 1;
}
if (sigaction(SIGINT, &act, NULL) < 0) {
perror ("sigaction failed for SIGINT signal\n");
return 1;
}
printf("PID of this program is %d.\n", getpid());
while (1)
sleep (10);

return 0;
}

[mstabie]

I think SIGPWR is used by some systems on shutdown. You cannot catch sigkill.