/*
 *  Copyright (C) 2020 - Vito Caputo - <vcaputo@pengaru.com>
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 3 as published
 *  by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	int		n = argc;
	struct pollfd	*pfds;

	assert(argc >= 1);

	pfds = calloc(n, sizeof(*pfds));
	if (!pfds) {
		fprintf(stderr, "Unable to allocate struct pollfd array: %s\n",
			strerror(errno));
		return EXIT_FAILURE;
	}

	for (int i = 0; i < n; i++) {
		if (i > 0) {
			const char	*path = argv[i];

			pfds[i].fd = open(path, O_RDONLY);
			if (pfds[i].fd == -1) {
				fprintf(stderr, "Unable to open \"%s\": %s\n",
					path, strerror(errno));
				return EXIT_FAILURE;
			}
		}
		pfds[i].events = POLLIN;
	}

	while (poll(pfds, n, -1) > 0) {
		for (int i = 0; i < n; i++) {
			char	buf[PIPE_BUF];
			ssize_t	rr, rw;

			if (pfds[i].revents & POLLHUP) {
				fprintf(stderr, "fd %i hangup, quitting\n",
					pfds[i].fd);
				return EXIT_SUCCESS;
			}

			if (!(pfds[i].revents & POLLIN))
				continue;

			rr = read(pfds[i].fd, buf, sizeof(buf));
			if (rr < 0) {
				fprintf(stderr, "Error reading fd %i: %s\n",
					pfds[i].fd, strerror(errno));
				return EXIT_FAILURE;
			}

			rw = write(1, buf, rr);
			if (rw < 0) {
				fprintf(stderr, "Error writing: %s\n",
					strerror(errno));
				return EXIT_FAILURE;
			}

			if (rw != rr) {
				fprintf(stderr, "Short write\n");
				return EXIT_FAILURE;
			}
		}
	}

	return EXIT_FAILURE;
}