summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/ttyname.c
blob: 6cec3a90130a60288acc5678281178664ab7c4a5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
/* Copyright (C) 1991-1993,1996-2002,2006,2009,2010
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#include <stdio-common/_itoa.h>
#include <kernel-features.h>

#if 0
/* Is this used anywhere?  It is not exported.  */
char *__ttyname;
#endif

static char *getttyname (const char *dev, dev_t mydev,
			 ino64_t myino, int save, int *dostat)
     internal_function;


libc_freeres_ptr (static char *getttyname_name);

static char *
internal_function attribute_compat_text_section
getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
{
  static size_t namelen;
  struct stat64 st;
  DIR *dirstream;
  struct dirent64 *d;
  size_t devlen = strlen (dev) + 1;

  dirstream = __opendir (dev);
  if (dirstream == NULL)
    {
      *dostat = -1;
      return NULL;
    }

  /* Prepare for the loop.  If we already have a buffer copy the directory
     name we look at into it.  */
  if (devlen < namelen)
    *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';

  while ((d = __readdir64 (dirstream)) != NULL)
    if ((d->d_fileno == myino || *dostat)
	&& strcmp (d->d_name, "stdin")
	&& strcmp (d->d_name, "stdout")
	&& strcmp (d->d_name, "stderr"))
      {
	size_t dlen = _D_ALLOC_NAMLEN (d);
	if (devlen + dlen > namelen)
	  {
	    free (getttyname_name);
	    namelen = 2 * (devlen + dlen); /* Big enough.  */
	    getttyname_name = malloc (namelen);
	    if (! getttyname_name)
	      {
		*dostat = -1;
		/* Perhaps it helps to free the directory stream buffer.  */
		(void) __closedir (dirstream);
		return NULL;
	      }
	    *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
	  }
	memcpy (&getttyname_name[devlen], d->d_name, dlen);
	if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
#ifdef _STATBUF_ST_RDEV
	    && S_ISCHR (st.st_mode) && st.st_rdev == mydev
#else
	    && d->d_fileno == myino && st.st_dev == mydev
#endif
	   )
	  {
	    (void) __closedir (dirstream);
#if 0
	    __ttyname = getttyname_name;
#endif
	    __set_errno (save);
	    return getttyname_name;
	  }
      }

  (void) __closedir (dirstream);
  __set_errno (save);
  return NULL;
}


/* Static buffer in `ttyname'.  */
libc_freeres_ptr (static char *ttyname_buf);


/* Return the pathname of the terminal FD is open on, or NULL on errors.
   The returned storage is good only until the next call to this function.  */
char *
ttyname (int fd)
{
  static size_t buflen;
  char procname[30];
  struct stat64 st, st1;
  int dostat = 0;
  char *name;
  int save = errno;
  struct termios term;

  /* isatty check, tcgetattr is used because it sets the correct
     errno (EBADF resp. ENOTTY) on error.  */
  if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
    return NULL;

  if (__fxstat64 (_STAT_VER, fd, &st) < 0)
    return NULL;

  /* We try using the /proc filesystem.  */
  *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';

  if (buflen == 0)
    {
      buflen = 4095;
      ttyname_buf = (char *) malloc (buflen + 1);
      if (ttyname_buf == NULL)
	{
	  buflen = 0;
	  return NULL;
	}
    }

  ssize_t len = __readlink (procname, ttyname_buf, buflen);
  if (__builtin_expect (len == -1 && errno == ENOENT, 0))
    {
      __set_errno (EBADF);
      return NULL;
    }

  if (__builtin_expect (len != -1
#ifndef __ASSUME_PROC_SELF_FD_SYMLINK
			/* This is for Linux 2.0.  */
			&& ttyname_buf[0] != '['
#endif
			, 1))
    {
      if ((size_t) len >= buflen)
	return NULL;

#define UNREACHABLE_LEN strlen ("(unreachable)")
      if (len > UNREACHABLE_LEN
	  && memcmp (ttyname_buf, "(unreachable)", UNREACHABLE_LEN) == 0)
	{
	  memmove (ttyname_buf, ttyname_buf + UNREACHABLE_LEN,
		   len - UNREACHABLE_LEN);
	  len -= UNREACHABLE_LEN;
	}

      /* readlink need not terminate the string.  */
      ttyname_buf[len] = '\0';

      /* Verify readlink result, fall back on iterating through devices.  */
      if (ttyname_buf[0] == '/'
	  && __xstat64 (_STAT_VER, ttyname_buf, &st1) == 0
#ifdef _STATBUF_ST_RDEV
	  && S_ISCHR (st1.st_mode)
	  && st1.st_rdev == st.st_rdev
#else
	  && st1.st_ino == st.st_ino
	  && st1.st_dev == st.st_dev
#endif
	  )
	return ttyname_buf;
    }

  if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
    {
#ifdef _STATBUF_ST_RDEV
      name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
#else
      name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
#endif
    }
  else
    {
      __set_errno (save);
      name = NULL;
    }

  if (!name && dostat != -1)
    {
#ifdef _STATBUF_ST_RDEV
      name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
#else
      name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
#endif
    }

  if (!name && dostat != -1)
    {
      dostat = 1;
#ifdef _STATBUF_ST_RDEV
      name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
#else
      name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
#endif
    }

  return name;
}