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28f540f4 RM |
1 | /* Copyright (C) 1991, 1992, 1993 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 Library General Public License as | |
6 | published by the Free Software Foundation; either version 2 of the | |
7 | 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 | Library General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Library General Public | |
15 | License along with the GNU C Library; see the file COPYING.LIB. If | |
16 | not, write to the Free Software Foundation, Inc., 675 Mass Ave, | |
17 | Cambridge, MA 02139, USA. */ | |
18 | ||
19 | #include <ansidecl.h> | |
20 | #include <errno.h> | |
21 | #include <limits.h> | |
22 | #include <stddef.h> | |
23 | #include <dirent.h> | |
24 | #include <sys/types.h> | |
25 | #include <sys/stat.h> | |
26 | #include <unistd.h> | |
27 | #include <string.h> | |
28 | #include <stdlib.h> | |
29 | ||
30 | char *__ttyname = NULL; | |
31 | ||
32 | /* Return the pathname of the terminal FD is open on, or NULL on errors. | |
33 | The returned storage is good only until the next call to this function. */ | |
34 | char * | |
35 | DEFUN(ttyname, (fd), int fd) | |
36 | { | |
37 | static CONST char dev[] = "/dev"; | |
38 | static char *name; | |
39 | static size_t namelen = 0; | |
40 | struct stat st; | |
41 | dev_t mydev; | |
42 | ino_t myino; | |
43 | DIR *dirstream; | |
44 | struct dirent *d; | |
45 | int save = errno; | |
46 | ||
47 | if (fstat (fd, &st) < 0) | |
48 | return NULL; | |
49 | mydev = st.st_dev; | |
50 | myino = st.st_ino; | |
51 | ||
52 | dirstream = opendir (dev); | |
53 | if (dirstream == NULL) | |
54 | return NULL; | |
55 | ||
56 | while ((d = readdir (dirstream)) != NULL) | |
57 | if (d->d_fileno == myino) | |
58 | { | |
59 | if (sizeof (dev) + d->d_namlen + 1 > namelen) | |
60 | { | |
61 | free (name); | |
62 | namelen = 2 * (sizeof (dev) + d->d_namlen + 1); /* Big enough. */ | |
63 | name = malloc (namelen); | |
64 | if (! name) | |
65 | return NULL; | |
66 | (void) memcpy (name, dev, sizeof (dev) - 1); | |
67 | name[sizeof (dev) - 1] = '/'; | |
68 | } | |
69 | (void) memcpy (&name[sizeof (dev)], d->d_name, d->d_namlen + 1); | |
70 | if (stat (name, &st) == 0 && st.st_dev == mydev) | |
71 | { | |
72 | (void) closedir (dirstream); | |
73 | __ttyname = name; | |
74 | errno = save; | |
75 | return name; | |
76 | } | |
77 | } | |
78 | ||
79 | (void) closedir (dirstream); | |
80 | errno = save; | |
81 | return NULL; | |
82 | } |