ctermid.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: stable/11/lib/libc/gen/ctermid.c 330897 2018-03-14 03:19:51Z eadler $");
31
32#include <sys/param.h>
33#include <sys/stat.h>
34#include <sys/sysctl.h>
35
36#include <errno.h>
37#include <paths.h>
38#include <stdio.h>
39#include <string.h>
40
41#define	LEN_PATH_DEV	(sizeof(_PATH_DEV) - 1)
42
43char *
44ctermid(char *s)
45{
46	static char def[sizeof(_PATH_DEV) + SPECNAMELEN];
47	struct stat sb;
48	size_t dlen;
49	int sverrno;
50
51	if (s == NULL) {
52		s = def;
53		dlen = sizeof(def) - LEN_PATH_DEV;
54	} else
55		dlen = L_ctermid - LEN_PATH_DEV;
56	strcpy(s, _PATH_TTY);
57
58	/* Attempt to perform a lookup of the actual TTY pathname. */
59	sverrno = errno;
60	if (stat(_PATH_TTY, &sb) == 0 && S_ISCHR(sb.st_mode))
61		(void)sysctlbyname("kern.devname", s + LEN_PATH_DEV,
62		    &dlen, &sb.st_rdev, sizeof(sb.st_rdev));
63	errno = sverrno;
64	return (s);
65}
66
67char *
68ctermid_r(char *s)
69{
70
71	return (s != NULL ? ctermid(s) : NULL);
72}
73