ptsname.c revision 367512 
1/*-
2 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Portions of this software were developed under sponsorship from Snow
6 * B.V., the Netherlands.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31#ifndef lint
32__FBSDID("$FreeBSD: stable/11/lib/libc/stdlib/ptsname.c 367512 2020-11-09 01:56:06Z delphij $");
33#endif /* not lint */
34
35#include "namespace.h"
36#include <sys/param.h>
37#include <sys/ioctl.h>
38
39#include <errno.h>
40#include <paths.h>
41#include <stdlib.h>
42#include <string.h>
43#include "un-namespace.h"
44
45/*
46 * __isptmaster():  return whether the file descriptor refers to a
47 *                  pseudo-terminal master device.
48 */
49static int
50__isptmaster(int fildes)
51{
52
53	if (_ioctl(fildes, TIOCPTMASTER) == 0)
54		return (0);
55
56	if (errno != EBADF)
57		errno = EINVAL;
58
59	return (-1);
60}
61
62/*
63 * In our implementation, grantpt() and unlockpt() don't actually have
64 * any use, because PTY's are created on the fly and already have proper
65 * permissions upon creation.
66 *
67 * Just make sure `fildes' actually points to a real PTY master device.
68 */
69__strong_reference(__isptmaster, grantpt);
70__strong_reference(__isptmaster, unlockpt);
71
72/*
73 * ptsname_r(): return the pathname of the slave pseudo-terminal device
74 *              associated with the specified master.
75 */
76int
77__ptsname_r(int fildes, char *buffer, size_t buflen)
78{
79
80	if (buflen <= sizeof(_PATH_DEV)) {
81		errno = ERANGE;
82		return (-1);
83	}
84
85	/* Make sure fildes points to a master device. */
86	if (__isptmaster(fildes) != 0)
87		return (-1);
88
89	memcpy(buffer, _PATH_DEV, sizeof(_PATH_DEV));
90	buffer += sizeof(_PATH_DEV) - 1;
91	buflen -= sizeof(_PATH_DEV) - 1;
92
93	if (fdevname_r(fildes, buffer, buflen) == NULL) {
94		if (errno == EINVAL)
95			errno = ERANGE;
96		return (-1);
97	}
98
99	return (0);
100}
101
102__strong_reference(__ptsname_r, ptsname_r);
103
104/*
105 * ptsname():  return the pathname of the slave pseudo-terminal device
106 *             associated with the specified master.
107 */
108char *
109ptsname(int fildes)
110{
111	static char pt_slave[sizeof(_PATH_DEV) + SPECNAMELEN];
112
113	if (__ptsname_r(fildes, pt_slave, sizeof(pt_slave)) == 0)
114		return (pt_slave);
115
116	return (NULL);
117}
118