xref: /freebsd/lib/libc/gen/ctermid.c (revision 0a36787e4c1fa0cf77dcf83be0867178476e372b)
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("$FreeBSD$");
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 
43 char *
44 ctermid(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 
67 char *
68 ctermid_r(char *s)
69 {
70 
71 	return (s != NULL ? ctermid(s) : NULL);
72 }
73