1/* Copyright (C) 1998-2018 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <paths.h>
21#include <stdlib.h>
22#include <string.h>
23#include <sys/ioctl.h>
24#include <sys/stat.h>
25#include <sys/sysmacros.h>
26#include <termios.h>
27#include <unistd.h>
28
29#include <_itoa.h>
30
31/* Check if DEV corresponds to a master pseudo terminal device. */
32#define MASTER_P(Dev) \
33 (__gnu_dev_major ((Dev)) == 2 \
34 || (__gnu_dev_major ((Dev)) == 4 \
35 && __gnu_dev_minor ((Dev)) >= 128 && __gnu_dev_minor ((Dev)) < 192) \
36 || (__gnu_dev_major ((Dev)) >= 128 && __gnu_dev_major ((Dev)) < 136))
37
38/* Check if DEV corresponds to a slave pseudo terminal device. */
39#define SLAVE_P(Dev) \
40 (__gnu_dev_major ((Dev)) == 3 \
41 || (__gnu_dev_major ((Dev)) == 4 \
42 && __gnu_dev_minor ((Dev)) >= 192 && __gnu_dev_minor ((Dev)) < 256) \
43 || (__gnu_dev_major ((Dev)) >= 136 && __gnu_dev_major ((Dev)) < 144))
44
45/* Note that major number 4 corresponds to the old BSD style pseudo
46 terminal devices. As of Linux 2.1.115 these are no longer
47 supported. They have been replaced by major numbers 2 (masters)
48 and 3 (slaves). */
49
50/* Directory where we can find the slave pty nodes. */
51#define _PATH_DEVPTS "/dev/pts/"
52
53/* The are declared in getpt.c. */
54extern const char __libc_ptyname1[] attribute_hidden;
55extern const char __libc_ptyname2[] attribute_hidden;
56
57/* Static buffer for `ptsname'. */
58static char buffer[sizeof (_PATH_DEVPTS) + 20];
59
60
61/* Return the pathname of the pseudo terminal slave associated with
62 the master FD is open on, or NULL on errors.
63 The returned storage is good until the next call to this function. */
64char *
65ptsname (int fd)
66{
67 return __ptsname_r (fd, buffer, sizeof (buffer)) != 0 ? NULL : buffer;
68}
69
70
71int
72__ptsname_internal (int fd, char *buf, size_t buflen, struct stat64 *stp)
73{
74 int save_errno = errno;
75 unsigned int ptyno;
76
77 if (!__isatty (fd))
78 {
79 __set_errno (ENOTTY);
80 return ENOTTY;
81 }
82
83#ifdef TIOCGPTN
84 if (__ioctl (fd, TIOCGPTN, &ptyno) == 0)
85 {
86 /* Buffer we use to print the number in. For a maximum size for
87 `int' of 8 bytes we never need more than 20 digits. */
88 char numbuf[21];
89 const char *devpts = _PATH_DEVPTS;
90 const size_t devptslen = strlen (_PATH_DEVPTS);
91 char *p;
92
93 numbuf[sizeof (numbuf) - 1] = '\0';
94 p = _itoa_word (ptyno, &numbuf[sizeof (numbuf) - 1], 10, 0);
95
96 if (buflen < devptslen + (&numbuf[sizeof (numbuf)] - p))
97 {
98 __set_errno (ERANGE);
99 return ERANGE;
100 }
101
102 memcpy (__stpcpy (buf, devpts), p, &numbuf[sizeof (numbuf)] - p);
103 }
104 else if (errno != EINVAL)
105 return errno;
106 else
107#endif
108 {
109 char *p;
110
111 if (buflen < strlen (_PATH_TTY) + 3)
112 {
113 __set_errno (ERANGE);
114 return ERANGE;
115 }
116
117 if (__fxstat64 (_STAT_VER, fd, stp) < 0)
118 return errno;
119
120 /* Check if FD really is a master pseudo terminal. */
121 if (! MASTER_P (stp->st_rdev))
122 {
123 __set_errno (ENOTTY);
124 return ENOTTY;
125 }
126
127 ptyno = __gnu_dev_minor (stp->st_rdev);
128
129 if (ptyno / 16 >= strlen (__libc_ptyname1))
130 {
131 __set_errno (ENOTTY);
132 return ENOTTY;
133 }
134
135 p = __stpcpy (buf, _PATH_TTY);
136 p[0] = __libc_ptyname1[ptyno / 16];
137 p[1] = __libc_ptyname2[ptyno % 16];
138 p[2] = '\0';
139 }
140
141 if (__xstat64 (_STAT_VER, buf, stp) < 0)
142 return errno;
143
144 /* Check if the name we're about to return really corresponds to a
145 slave pseudo terminal. */
146 if (! S_ISCHR (stp->st_mode) || ! SLAVE_P (stp->st_rdev))
147 {
148 /* This really is a configuration problem. */
149 __set_errno (ENOTTY);
150 return ENOTTY;
151 }
152
153 __set_errno (save_errno);
154 return 0;
155}
156
157
158/* Store at most BUFLEN characters of the pathname of the slave pseudo
159 terminal associated with the master FD is open on in BUF.
160 Return 0 on success, otherwise an error number. */
161int
162__ptsname_r (int fd, char *buf, size_t buflen)
163{
164 struct stat64 st;
165 return __ptsname_internal (fd, buf, buflen, &st);
166}
167weak_alias (__ptsname_r, ptsname_r)
168