sysdeps/posix/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 <unistd.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27
  28 #ifndef MIN
  29 # define MIN(a, b) ((a) < (b) ? (a) : (b))
  30 #endif
  31
  32 static const char dev[] = "/dev";
  33
  34 static int getttyname_r (int fd, char *buf, size_t buflen,
  35                          dev_t mydev, ino_t myino, int save,
  36                          int *dostat) __THROW internal_function;
  37
  38 static int
  39 internal_function
  40 getttyname_r (int fd, char *buf, size_t buflen, dev_t mydev, ino_t myino,
  41               int save, int *dostat)
  42 {
  43   struct stat st;
  44   DIR *dirstream;
  45   struct dirent *d;
  46
  47   dirstream = __opendir (dev);
  48   if (dirstream == NULL)
  49     {
  50       *dostat = -1;
  51       return errno;
  52     }
  53
  54   while ((d = __readdir (dirstream)) != NULL)
  55     if (((ino_t) 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[sizeof (dev)], d->d_name, needed);
  72         cp[0] = '\0';
  73
  74         if (stat (buf, &st) == 0
  75 #ifdef _STATBUF_ST_RDEV
  76             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  77 #else
  78             && (ino_t) 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   struct stat st;
 101   int dostat = 0;
 102   int save = errno;
 103   int ret;
 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 < (int) (sizeof (dev) + 1))
 114     {
 115       __set_errno (ERANGE);
 116       return ERANGE;
 117     }
 118
 119   if (!__isatty (fd))
 120     {
 121       __set_errno (ENOTTY);
 122       return ENOTTY;
 123     }
 124
 125   if (fstat (fd, &st) < 0)
 126     return errno;
 127
 128   /* Prepare the result buffer.  */
 129   memcpy (buf, dev, sizeof (dev) - 1);
 130   buf[sizeof (dev) - 1] = '/';
 131   buflen -= sizeof (dev);
 132
 133 #ifdef _STATBUF_ST_RDEV
 134   ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,
 135                       &dostat);
 136 #else
 137   ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,
 138                       &dostat);
 139 #endif
 140
 141   if (ret && dostat != -1)
 142     {
 143       dostat = 1;
 144 #ifdef _STATBUF_ST_RDEV
 145       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino,
 146                           save, &dostat);
 147 #else
 148       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino,
 149                           save, &dostat);
 150 #endif
 151     }
 152
 153   return ret;
 154 }
 155
 156 weak_alias (__ttyname_r, ttyname_r)