sysdeps/unix/sysv/linux/ttyname_r.c

   1 /* Copyright (C) 1991-2014 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 #include <kernel-features.h>
  31
  32 static int getttyname_r (char *buf, size_t buflen,
  33                          dev_t mydev, ino64_t myino, int save,
  34                          int *dostat) internal_function;
  35
  36 static int
  37 internal_function attribute_compat_text_section
  38 getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
  39               int save, int *dostat)
  40 {
  41   struct stat64 st;
  42   DIR *dirstream;
  43   struct dirent64 *d;
  44   size_t devlen = strlen (buf);
  45
  46   dirstream = __opendir (buf);
  47   if (dirstream == NULL)
  48     {
  49       *dostat = -1;
  50       return errno;
  51     }
  52
  53   while ((d = __readdir64 (dirstream)) != NULL)
  54     if ((d->d_fileno == myino || *dostat)
  55         && strcmp (d->d_name, "stdin")
  56         && strcmp (d->d_name, "stdout")
  57         && strcmp (d->d_name, "stderr"))
  58       {
  59         char *cp;
  60         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  61
  62         if (needed > buflen)
  63           {
  64             *dostat = -1;
  65             (void) __closedir (dirstream);
  66             __set_errno (ERANGE);
  67             return ERANGE;
  68           }
  69
  70         cp = __stpncpy (buf + devlen, d->d_name, needed);
  71         cp[0] = '\0';
  72
  73         if (__xstat64 (_STAT_VER, buf, &st) == 0
  74 #ifdef _STATBUF_ST_RDEV
  75             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  76 #else
  77             && d->d_fileno == myino && st.st_dev == mydev
  78 #endif
  79            )
  80           {
  81             (void) __closedir (dirstream);
  82             __set_errno (save);
  83             return 0;
  84           }
  85       }
  86
  87   (void) __closedir (dirstream);
  88   __set_errno (save);
  89   /* It is not clear what to return in this case.  `isatty' says FD
  90      refers to a TTY but no entry in /dev has this inode.  */
  91   return ENOTTY;
  92 }
  93
  94 /* Store at most BUFLEN character of the pathname of the terminal FD is
  95    open on in BUF.  Return 0 on success,  otherwise an error number.  */
  96 int
  97 __ttyname_r (int fd, char *buf, size_t buflen)
  98 {
  99   char procname[30];
 100   struct stat64 st, st1;
 101   int dostat = 0;
 102   int save = errno;
 103
 104   /* Test for the absolute minimal size.  This makes life easier inside
 105      the loop.  */
 106   if (!buf)
 107     {
 108       __set_errno (EINVAL);
 109       return EINVAL;
 110     }
 111
 112   if (buflen < sizeof ("/dev/pts/"))
 113     {
 114       __set_errno (ERANGE);
 115       return ERANGE;
 116     }
 117
 118   /* isatty check, tcgetattr is used because it sets the correct
 119      errno (EBADF resp. ENOTTY) on error.  */
 120   struct termios term;
 121   if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
 122     return errno;
 123
 124   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 125     return errno;
 126
 127   /* We try using the /proc filesystem.  */
 128   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 129
 130   ssize_t ret = __readlink (procname, buf, buflen - 1);
 131   if (__builtin_expect (ret == -1 && errno == ENAMETOOLONG, 0))
 132     {
 133       __set_errno (ERANGE);
 134       return ERANGE;
 135     }
 136
 137   if (__builtin_expect (ret != -1, 1))
 138     {
 139 #define UNREACHABLE_LEN strlen ("(unreachable)")
 140       if (ret > UNREACHABLE_LEN
 141           && memcmp (buf, "(unreachable)", UNREACHABLE_LEN) == 0)
 142         {
 143           memmove (buf, buf + UNREACHABLE_LEN, ret - UNREACHABLE_LEN);
 144           ret -= UNREACHABLE_LEN;
 145         }
 146
 147       /* readlink need not terminate the string.  */
 148       buf[ret] = '\0';
 149
 150       /* Verify readlink result, fall back on iterating through devices.  */
 151       if (buf[0] == '/'
 152           && __xstat64 (_STAT_VER, buf, &st1) == 0
 153 #ifdef _STATBUF_ST_RDEV
 154           && S_ISCHR (st1.st_mode)
 155           && st1.st_rdev == st.st_rdev
 156 #else
 157           && st1.st_ino == st.st_ino
 158           && st1.st_dev == st.st_dev
 159 #endif
 160           )
 161         return 0;
 162     }
 163
 164   /* Prepare the result buffer.  */
 165   memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
 166   buflen -= sizeof ("/dev/pts/") - 1;
 167
 168   if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
 169     {
 170 #ifdef _STATBUF_ST_RDEV
 171       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 172                           &dostat);
 173 #else
 174       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 175                           &dostat);
 176 #endif
 177     }
 178   else
 179     {
 180       __set_errno (save);
 181       ret = ENOENT;
 182     }
 183
 184   if (ret && dostat != -1)
 185     {
 186       buf[sizeof ("/dev/") - 1] = '\0';
 187       buflen += sizeof ("pts/") - 1;
 188 #ifdef _STATBUF_ST_RDEV
 189       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 190                           &dostat);
 191 #else
 192       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 193                           &dostat);
 194 #endif
 195     }
 196
 197   if (ret && dostat != -1)
 198     {
 199       buf[sizeof ("/dev/") - 1] = '\0';
 200       dostat = 1;
 201 #ifdef _STATBUF_ST_RDEV
 202       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
 203                           save, &dostat);
 204 #else
 205       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
 206                           save, &dostat);
 207 #endif
 208     }
 209
 210   return ret;
 211 }
 212
 213 weak_alias (__ttyname_r, ttyname_r)