1/* Copyright (C) 1991-2016 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
31static int getttyname_r (char *buf, size_t buflen,
32 dev_t mydev, ino64_t myino, int save,
33 int *dostat) internal_function;
34
35static int
36internal_function attribute_compat_text_section
37getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
38 int save, int *dostat)
39{
40 struct stat64 st;
41 DIR *dirstream;
42 struct dirent64 *d;
43 size_t devlen = strlen (buf);
44
45 dirstream = __opendir (buf);
46 if (dirstream == NULL)
47 {
48 *dostat = -1;
49 return errno;
50 }
51
52 while ((d = __readdir64 (dirstream)) != NULL)
53 if ((d->d_fileno == myino || *dostat)
54 && strcmp (d->d_name, "stdin")
55 && strcmp (d->d_name, "stdout")
56 && strcmp (d->d_name, "stderr"))
57 {
58 char *cp;
59 size_t needed = _D_EXACT_NAMLEN (d) + 1;
60
61 if (needed > buflen)
62 {
63 *dostat = -1;
64 (void) __closedir (dirstream);
65 __set_errno (ERANGE);
66 return ERANGE;
67 }
68
69 cp = __stpncpy (buf + devlen, d->d_name, needed);
70 cp[0] = '\0';
71
72 if (__xstat64 (_STAT_VER, buf, &st) == 0
73#ifdef _STATBUF_ST_RDEV
74 && S_ISCHR (st.st_mode) && st.st_rdev == mydev
75#else
76 && d->d_fileno == myino && st.st_dev == mydev
77#endif
78 )
79 {
80 (void) __closedir (dirstream);
81 __set_errno (save);
82 return 0;
83 }
84 }
85
86 (void) __closedir (dirstream);
87 __set_errno (save);
88 /* It is not clear what to return in this case. `isatty' says FD
89 refers to a TTY but no entry in /dev has this inode. */
90 return ENOTTY;
91}
92
93/* Store at most BUFLEN character of the pathname of the terminal FD is
94 open on in BUF. Return 0 on success, otherwise an error number. */
95int
96__ttyname_r (int fd, char *buf, size_t buflen)
97{
98 char procname[30];
99 struct stat64 st, st1;
100 int dostat = 0;
101 int save = errno;
102
103 /* Test for the absolute minimal size. This makes life easier inside
104 the loop. */
105 if (!buf)
106 {
107 __set_errno (EINVAL);
108 return EINVAL;
109 }
110
111 if (buflen < sizeof ("/dev/pts/"))
112 {
113 __set_errno (ERANGE);
114 return ERANGE;
115 }
116
117 /* isatty check, tcgetattr is used because it sets the correct
118 errno (EBADF resp. ENOTTY) on error. */
119 struct termios term;
120 if (__glibc_unlikely (__tcgetattr (fd, &term) < 0))
121 return errno;
122
123 if (__fxstat64 (_STAT_VER, fd, &st) < 0)
124 return errno;
125
126 /* We try using the /proc filesystem. */
127 *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
128
129 ssize_t ret = __readlink (procname, buf, buflen - 1);
130 if (__glibc_unlikely (ret == -1 && errno == ENAMETOOLONG))
131 {
132 __set_errno (ERANGE);
133 return ERANGE;
134 }
135
136 if (__glibc_likely (ret != -1))
137 {
138#define UNREACHABLE_LEN strlen ("(unreachable)")
139 if (ret > UNREACHABLE_LEN
140 && memcmp (buf, "(unreachable)", UNREACHABLE_LEN) == 0)
141 {
142 memmove (buf, buf + UNREACHABLE_LEN, ret - UNREACHABLE_LEN);
143 ret -= UNREACHABLE_LEN;
144 }
145
146 /* readlink need not terminate the string. */
147 buf[ret] = '\0';
148
149 /* Verify readlink result, fall back on iterating through devices. */
150 if (buf[0] == '/'
151 && __xstat64 (_STAT_VER, buf, &st1) == 0
152#ifdef _STATBUF_ST_RDEV
153 && S_ISCHR (st1.st_mode)
154 && st1.st_rdev == st.st_rdev
155#else
156 && st1.st_ino == st.st_ino
157 && st1.st_dev == st.st_dev
158#endif
159 )
160 return 0;
161 }
162
163 /* Prepare the result buffer. */
164 memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
165 buflen -= sizeof ("/dev/pts/") - 1;
166
167 if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
168 {
169#ifdef _STATBUF_ST_RDEV
170 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
171 &dostat);
172#else
173 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
174 &dostat);
175#endif
176 }
177 else
178 {
179 __set_errno (save);
180 ret = ENOENT;
181 }
182
183 if (ret && dostat != -1)
184 {
185 buf[sizeof ("/dev/") - 1] = '\0';
186 buflen += sizeof ("pts/") - 1;
187#ifdef _STATBUF_ST_RDEV
188 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
189 &dostat);
190#else
191 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
192 &dostat);
193#endif
194 }
195
196 if (ret && dostat != -1)
197 {
198 buf[sizeof ("/dev/") - 1] = '\0';
199 dostat = 1;
200#ifdef _STATBUF_ST_RDEV
201 ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
202 save, &dostat);
203#else
204 ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
205 save, &dostat);
206#endif
207 }
208
209 return ret;
210}
211
212weak_alias (__ttyname_r, ttyname_r)
213