#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

int
cat(int fd, const char* filename)
{
	int c;
	char buf[8192];
	if (filename[0] == '-' && filename[1] != 'u')
		fd = 0;

	if (fd != 0)
		fd = open(filename, O_RDONLY);

	if (fd == -1) {
		fprintf(stderr, "error opening %s: %s\n", filename, strerror(errno));
		return -1;
	}

	while ((c = read(fd, buf, sizeof(buf))) > 0) {
		if (c == -1)
			return -1;
		write(1, buf, c);
	}
	close(fd);
	return 0;
}
int
main(int argc, char* argv[])
{
	getopt(argc, argv, "u");
	if (argc == optind)
		cat(0, "-");
	for (int i = optind; i < argc; i++)
		cat(1, argv[i]);

	return 0;
}