tii.c

/*
 * Tiny frontend for ii and ii-like programs.
 * Inspired by sic from suckless
 * http://tools.suckless.org/sic
 * And by lchat from younix
 * https://github.com/younix/lchat
 * Although tii contains code from neither.
 */

#include <sys/types.h>
#include <sys/event.h>	/* kqueue(2) */
#include <sys/time.h>

#include <err.h>
#include <fcntl.h>	/* open(2) */
#include <stdio.h>	/* printf(3) setvbuf(3) */
#include <stdlib.h>	/* getenv(3) */
#include <string.h>	/* strdup(3) */
#include <unistd.h>	/* getopt(3) write(2) read(2) */

static void
usage(void)
{
	fprintf(stderr, "tii [-h] [-i in] [-o out]\n");
	exit(1);
}

int
main(int argc, char *argv[])
{
	struct kevent chlist[2];	/* events to monitor */
	int kq, ch, in_fd, out_fd;
	char *in_file = NULL, *out_file = NULL;

	in_file = strdup("./in");
	out_file = strdup("./out");

	while ((ch = getopt(argc, argv, "i:o:h")) != -1) {
		switch (ch) {
		case 'i':
			in_file = strdup(optarg);
			break;
		case 'o':
			out_file = strdup(optarg);
			break;
		case 'h':
		default:
			usage();
			/* NOTREACHED */
		}
	}
	if (argc - optind > 0)
		usage();
	if (in_file == NULL || out_file == NULL)
		err(1, "strdup");

	in_fd = open(in_file, O_WRONLY|O_APPEND);
	out_fd = open(out_file, O_RDONLY);
	if ((in_fd == -1 ) || (out_fd == -1))
		err(1, "opening in out files");

	free(in_file);
	free(out_file);

	if ((setvbuf(stdin, NULL, _IONBF, 0)) != 0)
		err(1, "setvbuf stdin");
	if ((setvbuf(stdout, NULL, _IONBF, 0)) != 0)
		err(1, "setvbuf stdout");

	if ((kq = kqueue()) == -1)
		err(1, "kqueue()");

	EV_SET(&chlist[0], out_fd, EVFILT_READ, EV_ADD, 0, 0, 0);
	EV_SET(&chlist[1], STDIN_FILENO, EVFILT_READ, EV_ADD, 0, 0, 0);

	for (;;) {
		int i, nev;
		struct kevent evlist[2];	/* events that were triggered */

		nev = kevent(kq, chlist, 2, evlist, 2, NULL);	/* block indefinitely */
		if (nev == -1)
			err(1, "kevent()");

		for (i = 0; i < nev; i++) {
			int res = 0;
			char buf[512];
			ssize_t bufl;

			if (evlist[i].flags & EV_ERROR)
				err(1, "evlist EV_ERROR");
			if (evlist[i].data <= 0)
				break;	/* we only append */

			bufl = read(evlist[i].ident, buf, sizeof buf);
			if (bufl == -1 )
				err(1, "read");

			if (evlist[i].ident == out_fd) {	/* can't switch-case, out_fd isn't static */
				res = write(STDOUT_FILENO, buf, bufl);
			} else if (evlist[i].ident == STDIN_FILENO) {
				res = write(in_fd, buf, bufl);
			}
			if (res == -1)
				err(1, "write");
		}
	}
	return 0;
}