/*
 * sigaction.c 
 * Demonstrates how to use sigaction to handle signals and gather signal info.
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>

void sigactionFunc(int sig, siginfo_t *info, void *context)
{
	fprintf(stdout,"Received Signal: %s\n",strsignal(sig));

	fprintf(stdout,"signo: %d\n",info->si_signo);
	fprintf(stdout,"sig errno: %d\n",info->si_errno);
	fprintf(stdout,"sig code: %d\n",info->si_code);
	fprintf(stdout,"sig pid: %d\n",info->si_pid);
	fprintf(stdout,"sig uid: %d\n",info->si_uid);

	fprintf(stdout,"why the signal was sent: \n");

	switch(info->si_code)				/* look at your definitions in siginfo.h for theses codes */
	{
		case SI_USER:
			fprintf(stdout,"sent by kill, sigsend\n");
			break;

		case SI_KERNEL:
			fprintf(stdout,"sent by the kernel\n");
			break;

		case SI_QUEUE:
			fprintf(stdout,"sent by sigqueue\n");
			break;

		case SI_TIMER:
			fprintf(stdout,"sent by timer\n");
			break;

		case SI_MESGQ:
			fprintf(stdout,"sent by real time mesgq state change\n");
			break;

		case SI_ASYNCIO:
			fprintf(stdout,"sent by AIO completion\n");
			break;

		case SI_SIGIO:
			fprintf(stdout,"sent by queued SIGIO\n");
			break;

		case SI_TKILL:
			fprintf(stdout,"sent by tkill\n");
			break;

		case SI_ASYNCNL:
			fprintf(stdout,"sent by asynch name lookup completion\n");
			break;
	}

	fprintf(stdout,"\n\n");
	fflush(stdout);
}

int main(int argc, char **argv)
{
	struct sigaction act;
	sigset_t set;

	sigemptyset(&set);				/* not masking any signals */
	act.sa_mask=set;

	act.sa_sigaction=sigactionFunc;			/* handle signals with the sigactionFunc */
	act.sa_flags=SA_SIGINFO;			/* request siginfo_t be delivered when a signal arrives */


	/* apply the sigaction parameters we just set up to handle SIGHUP signals */

	if(sigaction(SIGHUP,&act,NULL)!=0)		/* NOTE: sigaction does not need to be reset each time a */
	{						/* signal is received as the signal function does */
		fprintf(stdout,"failed to apply sigaction, %s\n",strerror(errno));
		fflush(stdout);
		return -1;
	}

	/* now we send the process SIGHUP signals and see what happens */

	raise(SIGHUP);					/* send SIGHUP to this process using raise */

							/* NOTE: on my system raise is actually implemented with */
							/* the tkill function, this will be shown with the siginfo_t*/
							/* parameter in the sigcatchFunc */

	kill(getpid(),SIGHUP);				/* send SIGHUP to this process using kill */

	getchar();

	return 0;
}