/* Ring Indicator Logger, Sat Jun 26 22:15:31 CEST 2010, a.leofreddi */

#include <stdio.h>
#include <sys/ttycom.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <signal.h>

int main(int argc, char *argv[]) {
	if(argc != 3 && argc != 2) {
		fprintf(stderr, "Usage: %s port [pid]\n", argv[0]);

		return 1;
	}

	char *port = argv[1];

	int l = -1;

	int fd = open(port, O_RDONLY | O_NONBLOCK | O_NOCTTY);
	
	if(fd < 0) {
		fprintf(stderr, "Unable to open port: %i\n", errno);

		return 2;
	}
	
	int pid = 0;

	if(argv[2]) {
		pid = (int)strtol(argv[2], (char **)NULL, 10);

		if(pid == 0) {
			fprintf(stderr, "Invalid pid %s\n", argv[2]);

			return 3;
		}
	}

	printf("Port opened\n");

	for(;;) {
		int s;

		/* Read terminal status line: Clear To Send */
		ioctl(fd, TIOCMGET, &s);

		s = !!(s & TIOCM_RI);

		usleep(100000);

		if(l != -1 && l != s && s) {
			printf("Low to high transition\n", s);

			if(pid > 0)
				kill(pid, SIGUSR1);
		}

		l = s;
	}
}