sysdeps/unix/sysv/linux/ttyname_r.c

   1 /* Copyright (C) 1991-1993,1995-2001,2003,2006,2010
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <dirent.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <termios.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29
  30 #include <stdio-common/_itoa.h>
  31 #include <kernel-features.h>
  32
  33 static int getttyname_r (char *buf, size_t buflen,
  34                          dev_t mydev, ino64_t myino, int save,
  35                          int *dostat) internal_function;
  36
  37 static int
  38 internal_function attribute_compat_text_section
  39 getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
  40               int save, int *dostat)
  41 {
  42   struct stat64 st;
  43   DIR *dirstream;
  44   struct dirent64 *d;
  45   size_t devlen = strlen (buf);
  46
  47   dirstream = __opendir (buf);
  48   if (dirstream == NULL)
  49     {
  50       *dostat = -1;
  51       return errno;
  52     }
  53
  54   while ((d = __readdir64 (dirstream)) != NULL)
  55     if ((d->d_fileno == myino || *dostat)
  56         && strcmp (d->d_name, "stdin")
  57         && strcmp (d->d_name, "stdout")
  58         && strcmp (d->d_name, "stderr"))
  59       {
  60         char *cp;
  61         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  62
  63         if (needed > buflen)
  64           {
  65             *dostat = -1;
  66             (void) __closedir (dirstream);
  67             __set_errno (ERANGE);
  68             return ERANGE;
  69           }
  70
  71         cp = __stpncpy (buf + devlen, d->d_name, needed);
  72         cp[0] = '\0';
  73
  74         if (__xstat64 (_STAT_VER, buf, &st) == 0
  75 #ifdef _STATBUF_ST_RDEV
  76             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  77 #else
  78             && d->d_fileno == myino && st.st_dev == mydev
  79 #endif
  80            )
  81           {
  82             (void) __closedir (dirstream);
  83             __set_errno (save);
  84             return 0;
  85           }
  86       }
  87
  88   (void) __closedir (dirstream);
  89   __set_errno (save);
  90   /* It is not clear what to return in this case.  `isatty' says FD
  91      refers to a TTY but no entry in /dev has this inode.  */
  92   return ENOTTY;
  93 }
  94
  95 /* Store at most BUFLEN character of the pathname of the terminal FD is
  96    open on in BUF.  Return 0 on success,  otherwise an error number.  */
  97 int
  98 __ttyname_r (int fd, char *buf, size_t buflen)
  99 {
 100   char procname[30];
 101   struct stat64 st, st1;
 102   int dostat = 0;
 103   int save = errno;
 104
 105   /* Test for the absolute minimal size.  This makes life easier inside
 106      the loop.  */
 107   if (!buf)
 108     {
 109       __set_errno (EINVAL);
 110       return EINVAL;
 111     }
 112
 113   if (buflen < sizeof ("/dev/pts/"))
 114     {
 115       __set_errno (ERANGE);
 116       return ERANGE;
 117     }
 118
 119   /* isatty check, tcgetattr is used because it sets the correct
 120      errno (EBADF resp. ENOTTY) on error.  */
 121   struct termios term;
 122   if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
 123     return errno;
 124
 125   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 126     return errno;
 127
 128   /* We try using the /proc filesystem.  */
 129   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 130
 131   ssize_t ret = __readlink (procname, buf, buflen - 1);
 132   if (__builtin_expect (ret == -1 && errno == ENOENT, 0))
 133     {
 134       __set_errno (EBADF);
 135       return EBADF;
 136     }
 137
 138   if (__builtin_expect (ret == -1 && errno == ENAMETOOLONG, 0))
 139     {
 140       __set_errno (ERANGE);
 141       return ERANGE;
 142     }
 143
 144   if (__builtin_expect (ret != -1
 145 #ifndef __ASSUME_PROC_SELF_FD_SYMLINK
 146                         /* This is for Linux 2.0.  */
 147                         && buf[0] != '['
 148 #endif
 149                         , 1))
 150     {
 151 #define UNREACHABLE_LEN strlen ("(unreachable)")
 152       if (ret > UNREACHABLE_LEN
 153           && memcmp (buf, "(unreachable)", UNREACHABLE_LEN) == 0)
 154         {
 155           memmove (buf, buf + UNREACHABLE_LEN, ret - UNREACHABLE_LEN);
 156           ret -= UNREACHABLE_LEN;
 157         }
 158
 159       /* readlink need not terminate the string.  */
 160       buf[ret] = '\0';
 161
 162       /* Verify readlink result, fall back on iterating through devices.  */
 163       if (buf[0] == '/'
 164           && __xstat64 (_STAT_VER, buf, &st1) == 0
 165 #ifdef _STATBUF_ST_RDEV
 166           && S_ISCHR (st1.st_mode)
 167           && st1.st_rdev == st.st_rdev
 168 #else
 169           && st1.st_ino == st.st_ino
 170           && st1.st_dev == st.st_dev
 171 #endif
 172           )
 173         return 0;
 174     }
 175
 176   /* Prepare the result buffer.  */
 177   memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
 178   buflen -= sizeof ("/dev/pts/") - 1;
 179
 180   if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
 181     {
 182 #ifdef _STATBUF_ST_RDEV
 183       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 184                           &dostat);
 185 #else
 186       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 187                           &dostat);
 188 #endif
 189     }
 190   else
 191     {
 192       __set_errno (save);
 193       ret = ENOENT;
 194     }
 195
 196   if (ret && dostat != -1)
 197     {
 198       buf[sizeof ("/dev/") - 1] = '\0';
 199       buflen += sizeof ("pts/") - 1;
 200 #ifdef _STATBUF_ST_RDEV
 201       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 202                           &dostat);
 203 #else
 204       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 205                           &dostat);
 206 #endif
 207     }
 208
 209   if (ret && dostat != -1)
 210     {
 211       buf[sizeof ("/dev/") - 1] = '\0';
 212       dostat = 1;
 213 #ifdef _STATBUF_ST_RDEV
 214       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
 215                           save, &dostat);
 216 #else
 217       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
 218                           save, &dostat);
 219 #endif
 220     }
 221
 222   return ret;
 223 }
 224
 225 weak_alias (__ttyname_r, ttyname_r)