micro-utils/src/tee.c

#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include "config.h"

int main(int argc, char **argv) {
	int flag = O_TRUNC;

	int opt;
	while ((opt = getopt(argc, argv, "ai")) != -1) {
		switch (opt) {
			case 'a':
				flag = O_APPEND;
				break;

			case 'i':
				signal(SIGINT, SIG_IGN);
				break;

			default:
				puts("tee [ai] [file]\n\t-a Append\n\t-i Ignore interrupt signals");
				return 0;
		}
	}

	argv += optind;
	argc -= optind;

	int fd = STDOUT_FILENO;
	if (argc > 0 && strcmp(argv[0], "-")) {
		fd = open(argv[0], O_WRONLY | flag | O_CREAT, 0666);
		if (fd < 0) {
			fprintf(stderr, "tee: %s\n", strerror(errno));
			return 1;
		}
	}

	char buf[BUF_SIZE + 1];
	ssize_t bytes = 0;
	while ((bytes = read(STDIN_FILENO, buf, sizeof(buf)))) {
		int stat = write(STDOUT_FILENO, buf, bytes);

		int stat2 = bytes;
		if (argc > 0)
			stat2 = write(fd, buf, bytes);

		if (stat != bytes || stat2 != bytes) {
			fprintf(stderr, "tee: %s\n", strerror(errno));
			return 1;
		}
	}

	if (argc > 0 && strcmp(argv[0], "-"))
		close(fd);

	return 0;
}