1/* Copyright (C) 1998-2017 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 (major ((Dev)) == 2 \
34 || (major ((Dev)) == 4 && minor ((Dev)) >= 128 && minor ((Dev)) < 192) \
35 || (major ((Dev)) >= 128 && major ((Dev)) < 136))
36
37/* Check if DEV corresponds to a slave pseudo terminal device. */
38#define SLAVE_P(Dev) \
39 (major ((Dev)) == 3 \
40 || (major ((Dev)) == 4 && minor ((Dev)) >= 192 && minor ((Dev)) < 256) \
41 || (major ((Dev)) >= 136 && major ((Dev)) < 144))
42
43/* Note that major number 4 corresponds to the old BSD style pseudo
44 terminal devices. As of Linux 2.1.115 these are no longer
45 supported. They have been replaced by major numbers 2 (masters)
46 and 3 (slaves). */
47
48/* Directory where we can find the slave pty nodes. */
49#define _PATH_DEVPTS "/dev/pts/"
50
51/* The are declared in getpt.c. */
52extern const char __libc_ptyname1[] attribute_hidden;
53extern const char __libc_ptyname2[] attribute_hidden;
54
55/* Static buffer for `ptsname'. */
56static char buffer[sizeof (_PATH_DEVPTS) + 20];
57
58
59/* Return the pathname of the pseudo terminal slave associated with
60 the master FD is open on, or NULL on errors.
61 The returned storage is good until the next call to this function. */
62char *
63ptsname (int fd)
64{
65 return __ptsname_r (fd, buffer, sizeof (buffer)) != 0 ? NULL : buffer;
66}
67
68
69int
70__ptsname_internal (int fd, char *buf, size_t buflen, struct stat64 *stp)
71{
72 int save_errno = errno;
73 unsigned int ptyno;
74
75 if (buf == NULL)
76 {
77 __set_errno (EINVAL);
78 return EINVAL;
79 }
80
81 if (!__isatty (fd))
82 {
83 __set_errno (ENOTTY);
84 return ENOTTY;
85 }
86
87#ifdef TIOCGPTN
88 if (__ioctl (fd, TIOCGPTN, &ptyno) == 0)
89 {
90 /* Buffer we use to print the number in. For a maximum size for
91 `int' of 8 bytes we never need more than 20 digits. */
92 char numbuf[21];
93 const char *devpts = _PATH_DEVPTS;
94 const size_t devptslen = strlen (_PATH_DEVPTS);
95 char *p;
96
97 numbuf[sizeof (numbuf) - 1] = '\0';
98 p = _itoa_word (ptyno, &numbuf[sizeof (numbuf) - 1], 10, 0);
99
100 if (buflen < devptslen + (&numbuf[sizeof (numbuf)] - p))
101 {
102 __set_errno (ERANGE);
103 return ERANGE;
104 }
105
106 memcpy (__stpcpy (buf, devpts), p, &numbuf[sizeof (numbuf)] - p);
107 }
108 else if (errno != EINVAL)
109 return errno;
110 else
111#endif
112 {
113 char *p;
114
115 if (buflen < strlen (_PATH_TTY) + 3)
116 {
117 __set_errno (ERANGE);
118 return ERANGE;
119 }
120
121 if (__fxstat64 (_STAT_VER, fd, stp) < 0)
122 return errno;
123
124 /* Check if FD really is a master pseudo terminal. */
125 if (! MASTER_P (stp->st_rdev))
126 {
127 __set_errno (ENOTTY);
128 return ENOTTY;
129 }
130
131 ptyno = minor (stp->st_rdev);
132
133 if (ptyno / 16 >= strlen (__libc_ptyname1))
134 {
135 __set_errno (ENOTTY);
136 return ENOTTY;
137 }
138
139 p = __stpcpy (buf, _PATH_TTY);
140 p[0] = __libc_ptyname1[ptyno / 16];
141 p[1] = __libc_ptyname2[ptyno % 16];
142 p[2] = '\0';
143 }
144
145 if (__xstat64 (_STAT_VER, buf, stp) < 0)
146 return errno;
147
148 /* Check if the name we're about to return really corresponds to a
149 slave pseudo terminal. */
150 if (! S_ISCHR (stp->st_mode) || ! SLAVE_P (stp->st_rdev))
151 {
152 /* This really is a configuration problem. */
153 __set_errno (ENOTTY);
154 return ENOTTY;
155 }
156
157 __set_errno (save_errno);
158 return 0;
159}
160
161
162/* Store at most BUFLEN characters of the pathname of the slave pseudo
163 terminal associated with the master FD is open on in BUF.
164 Return 0 on success, otherwise an error number. */
165int
166__ptsname_r (int fd, char *buf, size_t buflen)
167{
168 struct stat64 st;
169 return __ptsname_internal (fd, buf, buflen, &st);
170}
171weak_alias (__ptsname_r, ptsname_r)
172