1/* vi: set sw=4 ts=4: */
2/*
3 * tty implementation for busybox
4 *
5 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10/* BB_AUDIT SUSv3 compliant */
11/* http://www.opengroup.org/onlinepubs/007904975/utilities/tty.html */
12
13#include "libbb.h"
14
15int tty_main(int argc, char **argv);
16int tty_main(int argc, char **argv)
17{
18	const char *s;
19	USE_INCLUDE_SUSv2(int silent;)	/* Note: No longer relevant in SUSv3. */
20	int retval;
21
22	xfunc_error_retval = 2;	/* SUSv3 requires > 1 for error. */
23
24	USE_INCLUDE_SUSv2(silent = getopt32(argv, "s");)
25
26	/* gnu tty outputs a warning that it is ignoring all args. */
27	bb_warn_ignoring_args(argc - optind);
28
29	retval = 0;
30
31	s = ttyname(0);
32	if (s == NULL) {
33	/* According to SUSv3, ttyname can on fail with EBADF or ENOTTY.
34	 * We know the file descriptor is good, so failure means not a tty. */
35		s = "not a tty";
36		retval = 1;
37	}
38	USE_INCLUDE_SUSv2(if (!silent) puts(s);)
39	SKIP_INCLUDE_SUSv2(puts(s);)
40
41	fflush_stdout_and_exit(retval);
42}
43