1/* Copyright (C) 1991-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <limits.h>
20#include <stddef.h>
21#include <dirent.h>
22#include <sys/types.h>
23#include <sys/stat.h>
24#include <termios.h>
25#include <unistd.h>
26#include <string.h>
27#include <stdlib.h>
28
29#include <_itoa.h>
30
31#include "ttyname.h"
32
33static int getttyname_r (char *buf, size_t buflen,
34 dev_t mydev, ino64_t myino, int save,
35 int *dostat) internal_function;
36
37static int
38internal_function attribute_compat_text_section
39getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
40 int save, int *dostat)
41{
42 struct stat64 st;
43 DIR *dirstream;
44 struct dirent64 *d;
45 size_t devlen = strlen (buf);
46
47 dirstream = __opendir (buf);
48 if (dirstream == NULL)
49 {
50 *dostat = -1;
51 return errno;
52 }
53
54 while ((d = __readdir64 (dirstream)) != NULL)
55 if ((d->d_fileno == myino || *dostat)
56 && strcmp (d->d_name, "stdin")
57 && strcmp (d->d_name, "stdout")
58 && strcmp (d->d_name, "stderr"))
59 {
60 char *cp;
61 size_t needed = _D_EXACT_NAMLEN (d) + 1;
62
63 if (needed > buflen)
64 {
65 *dostat = -1;
66 (void) __closedir (dirstream);
67 __set_errno (ERANGE);
68 return ERANGE;
69 }
70
71 cp = __stpncpy (buf + devlen, d->d_name, needed);
72 cp[0] = '\0';
73
74 if (__xstat64 (_STAT_VER, buf, &st) == 0
75#ifdef _STATBUF_ST_RDEV
76 && S_ISCHR (st.st_mode) && st.st_rdev == mydev
77#else
78 && d->d_fileno == myino && st.st_dev == mydev
79#endif
80 )
81 {
82 (void) __closedir (dirstream);
83 __set_errno (save);
84 return 0;
85 }
86 }
87
88 (void) __closedir (dirstream);
89 __set_errno (save);
90 /* It is not clear what to return in this case. `isatty' says FD
91 refers to a TTY but no entry in /dev has this inode. */
92 return ENOTTY;
93}
94
95/* Store at most BUFLEN character of the pathname of the terminal FD is
96 open on in BUF. Return 0 on success, otherwise an error number. */
97int
98__ttyname_r (int fd, char *buf, size_t buflen)
99{
100 char procname[30];
101 struct stat64 st, st1;
102 int dostat = 0;
103 int save = errno;
104
105 /* Test for the absolute minimal size. This makes life easier inside
106 the loop. */
107 if (!buf)
108 {
109 __set_errno (EINVAL);
110 return EINVAL;
111 }
112
113 if (buflen < sizeof ("/dev/pts/"))
114 {
115 __set_errno (ERANGE);
116 return ERANGE;
117 }
118
119 /* isatty check, tcgetattr is used because it sets the correct
120 errno (EBADF resp. ENOTTY) on error. */
121 struct termios term;
122 if (__glibc_unlikely (__tcgetattr (fd, &term) < 0))
123 return errno;
124
125 if (__fxstat64 (_STAT_VER, fd, &st) < 0)
126 return errno;
127
128 /* We try using the /proc filesystem. */
129 *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
130
131 ssize_t ret = __readlink (procname, buf, buflen - 1);
132 if (__glibc_unlikely (ret == -1 && errno == ENAMETOOLONG))
133 {
134 __set_errno (ERANGE);
135 return ERANGE;
136 }
137
138 if (__glibc_likely (ret != -1))
139 {
140#define UNREACHABLE_LEN strlen ("(unreachable)")
141 if (ret > UNREACHABLE_LEN
142 && memcmp (buf, "(unreachable)", UNREACHABLE_LEN) == 0)
143 {
144 memmove (buf, buf + UNREACHABLE_LEN, ret - UNREACHABLE_LEN);
145 ret -= UNREACHABLE_LEN;
146 }
147
148 /* readlink need not terminate the string. */
149 buf[ret] = '\0';
150
151 /* Verify readlink result, fall back on iterating through devices. */
152 if (buf[0] == '/'
153 && __xstat64 (_STAT_VER, buf, &st1) == 0
154#ifdef _STATBUF_ST_RDEV
155 && S_ISCHR (st1.st_mode)
156 && st1.st_rdev == st.st_rdev
157#endif
158 && st1.st_ino == st.st_ino
159 && st1.st_dev == st.st_dev)
160 return 0;
161
162 /* If the link doesn't exist, then it points to a device in another
163 * namespace.
164 */
165 if (is_pty (&st))
166 {
167 __set_errno (ENODEV);
168 return ENODEV;
169 }
170 }
171
172 /* Prepare the result buffer. */
173 memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
174 buflen -= sizeof ("/dev/pts/") - 1;
175
176 if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
177 {
178#ifdef _STATBUF_ST_RDEV
179 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
180 &dostat);
181#else
182 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
183 &dostat);
184#endif
185 }
186 else
187 {
188 __set_errno (save);
189 ret = ENOENT;
190 }
191
192 if (ret && dostat != -1)
193 {
194 buf[sizeof ("/dev/") - 1] = '\0';
195 buflen += sizeof ("pts/") - 1;
196#ifdef _STATBUF_ST_RDEV
197 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
198 &dostat);
199#else
200 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
201 &dostat);
202#endif
203 }
204
205 if (ret && dostat != -1)
206 {
207 buf[sizeof ("/dev/") - 1] = '\0';
208 dostat = 1;
209#ifdef _STATBUF_ST_RDEV
210 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
211 save, &dostat);
212#else
213 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
214 save, &dostat);
215#endif
216 }
217
218 return ret;
219}
220
221weak_alias (__ttyname_r, ttyname_r)
222