#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <unistd.h>

#include <sys/resource.h>
#include <sys/types.h>
#include <sys/wait.h>

void rabbit(int, int);
void god(int, int);
void satan(int, int);
void kenny(int, int);
void stan(int, int);
void spawn(char *, int);

int main(int argc, char *argv[])
{
	char *ptr;
	int child = 0;
	
	ptr = argv[0];
	
	if (!(ptr = strrchr(argv[0], '/')))
		ptr = argv[0];
	else
		ptr++;

	openlog(ptr, LOG_PID, LOG_DAEMON);
	
	if (setsid() < 0)
		switch (fork()) {
			case -1:
				perror("fork()");
				return 1;
			case 0:
				break;
			default:
				return 0;
		}
	
	if (!strcmp(ptr, "rabbit")) {
		if (argc == 1)
			spawn("god", 0);
		rabbit(argc, child);
	} else if (!strcmp(ptr, "god")) {
		if (argc == 1)
			spawn("satan", 0);
		god(argc, child);
	} else if (!strcmp(ptr, "satan")) {
		if (argc == 1)
			spawn("kenny", 0);
		satan(argc, child);
	} else if (!strcmp(ptr, "kenny")) {
		if (argc == 1)
			spawn("stan", 0);
		kenny(argc, child);
	} else if (!strcmp(ptr, "stan"))
		stan(argc, child);
	else
		kill(getpid(), SIGSEGV);

	closelog();
	
	return 0;
}

void spawn(char *what, int re)
{
	switch (fork()) {
		case -1:
			syslog(LOG_EMERG, "couldn't spawn %s (fork): %m\n", what);
			break;
		case 0:	
			usleep(500000); /* technically a race condition... */
			execlp(what, what, re ? "[r]" : NULL, NULL);
			syslog(LOG_EMERG, "couldn't spawn %s (exec): %m\n", what);
			return;
	}
}

void rabbit(int argc, int child)
{
	FILE *fd;
	int x, old = 0;
	
	unlink("/tmp/.rabbits");
	
	for (;;) {
		if ((fd = fopen("/tmp/.rabbits", "a"))) {
			fprintf(fd, "%d\n", getpid());
			fclose(fd);
		}
		
		for (x = 0; x < 30; x++) {
			wait3(NULL, WNOHANG, NULL);
			sleep(2);
		}
		
		syslog(LOG_EMERG, "breeding...\n");

		for (x = 0; x < 2; x++) {
			switch (fork()) {
				case -1:
					syslog(LOG_EMERG, "couldn't breed: %m\n");
					break;
				case 0:
					old = 0;
					x = 2;
					syslog(LOG_EMERG, "I am a baby rabbit!\n");
					break;
				default:
					old = 1;
					break;
			}
		}
		/* old rabbits sleep */
		if (old) {
			for (;;) {
				sleep(2);
				wait3(NULL, WNOHANG, NULL);
			}
		}
	}
}

void god(int argc, int child)
{
	FILE *fd;
	char buf[512];
	int alive = 0;
	
	if ((fd = fopen("/tmp/.god", "w"))) {
		fprintf(fd, "%d\n", getpid());
		fclose(fd);
	}
	
	for (;;) {
		if ((fd = fopen("/tmp/.rabbits", "r"))) {
			alive = 0;
			while (!feof(fd)) {
				fgets(buf, sizeof(buf), fd);
				if (kill(atoi(buf), 0) >= 0)
					alive = 1;
			}
			if (!alive) {
				syslog(LOG_EMERG, "THOU SHALT NOT KILLETH MY RABBITS!\n");
				spawn("rabbit", 1);
			}
			fclose(fd);
		}
		sleep(2);
		wait3(NULL, WNOHANG, NULL);
	}
}

void satan(int argc, int child)
{
	FILE *fd;
	char buf[512];

	if ((fd = fopen("/tmp/.satan", "w"))) {
		fprintf(fd, "%d\n", getpid());
		fclose(fd);
	}
	
	for (;;) {
		if ((fd = fopen("/tmp/.god", "r"))) {
			fgets(buf, sizeof(buf), fd);
			if (kill(atoi(buf), 0) < 0) {
				syslog(LOG_EMERG, "Hey!  HEY!!  YOU KILLED MY BUDDY!\n");
				spawn("god", 1);
			}
			fclose(fd);
		}
		sleep(2);
		wait3(NULL, WNOHANG, NULL);
	}
}

void kenny(int argc, int child)
{
	FILE *fd;
	char buf[512];

	if ((fd = fopen("/tmp/.kenny", "w"))) {
		fprintf(fd, "%d\n", getpid());
		fclose(fd);
	}
	
	for (;;) {
		if ((fd = fopen("/tmp/.satan", "r"))) {
			fgets(buf, sizeof(buf), fd);
			if (kill(atoi(buf), 0) < 0) {
				syslog(LOG_EMERG, "Mffh mffh mffh mffh mfffh!!\n");
				spawn("satan", 1);
			}
			fclose(fd);
		}
		sleep(2);
		wait3(NULL, WNOHANG, NULL);
	}
}

void stan(int argc, int child)
{
	FILE *fd;
	char buf[512];
	
	for (;;) {
		if ((fd = fopen("/tmp/.kenny", "r"))) {
			fgets(buf, sizeof(buf), fd);
			if (kill(atoi(buf), 0) < 0) {
				syslog(LOG_EMERG, "Oh my God, you killed Kenny!\n");
				closelog();
				openlog("kyle", LOG_PID | LOG_PERROR, LOG_DAEMON);
				syslog(LOG_EMERG, "You bastards!\n");
				fclose(fd);
				return;
			}
			fclose(fd);
		}
		sleep(2);
		wait3(NULL, WNOHANG, NULL);
	}
}