sysdeps/unix/sysv/linux/ttyname_r.c

   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
  31 static int getttyname_r (char *buf, size_t buflen,
  32                          dev_t mydev, ino64_t myino, int save,
  33                          int *dostat) internal_function;
  34
  35 static int
  36 internal_function attribute_compat_text_section
  37 getttyname_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.  */
  95 int
  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
 212 weak_alias (__ttyname_r, ttyname_r)