sysdeps/posix/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 <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 (fd, buf, buflen, mydev, myino, save, dostat)
  41      int fd;
  42      char *buf;
  43      size_t buflen;
  44      dev_t mydev;
  45      ino_t myino;
  46      int save;
  47      int *dostat;
  48 {
  49   struct stat st;
  50   DIR *dirstream;
  51   struct dirent *d;
  52
  53   dirstream = __opendir (dev);
  54   if (dirstream == NULL)
  55     {
  56       *dostat = -1;
  57       return errno;
  58     }
  59
  60   while ((d = __readdir (dirstream)) != NULL)
  61     if (((ino_t) d->d_fileno == myino || *dostat)
  62         && strcmp (d->d_name, "stdin")
  63         && strcmp (d->d_name, "stdout")
  64         && strcmp (d->d_name, "stderr"))
  65       {
  66         char *cp;
  67         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  68
  69         if (needed > buflen)
  70           {
  71             *dostat = -1;
  72             (void) __closedir (dirstream);
  73             __set_errno (ERANGE);
  74             return ERANGE;
  75           }
  76
  77         cp = __stpncpy (&buf[sizeof (dev)], d->d_name, needed);
  78         cp[0] = '\0';
  79
  80         if (stat (buf, &st) == 0
  81 #ifdef _STATBUF_ST_RDEV
  82             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  83 #else
  84             && (ino_t) d->d_fileno == myino && st.st_dev == mydev
  85 #endif
  86            )
  87           {
  88             (void) __closedir (dirstream);
  89             __set_errno (save);
  90             return 0;
  91           }
  92       }
  93
  94   (void) __closedir (dirstream);
  95   __set_errno (save);
  96   /* It is not clear what to return in this case.  `isatty' says FD
  97      refers to a TTY but no entry in /dev has this inode.  */
  98   return ENOTTY;
  99 }
 100
 101 /* Store at most BUFLEN character of the pathname of the terminal FD is
 102    open on in BUF.  Return 0 on success,  otherwise an error number.  */
 103 int
 104 __ttyname_r (fd, buf, buflen)
 105      int fd;
 106      char *buf;
 107      size_t buflen;
 108 {
 109   struct stat st;
 110   int dostat = 0;
 111   int save = errno;
 112   int ret;
 113
 114   /* Test for the absolute minimal size.  This makes life easier inside
 115      the loop.  */
 116   if (!buf)
 117     {
 118       __set_errno (EINVAL);
 119       return EINVAL;
 120     }
 121
 122   if (buflen < (int) (sizeof (dev) + 1))
 123     {
 124       __set_errno (ERANGE);
 125       return ERANGE;
 126     }
 127
 128   if (!__isatty (fd))
 129     {
 130       __set_errno (ENOTTY);
 131       return ENOTTY;
 132     }
 133
 134   if (fstat (fd, &st) < 0)
 135     return errno;
 136
 137   /* Prepare the result buffer.  */
 138   memcpy (buf, dev, sizeof (dev) - 1);
 139   buf[sizeof (dev) - 1] = '/';
 140   buflen -= sizeof (dev);
 141
 142 #ifdef _STATBUF_ST_RDEV
 143   ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,
 144                       &dostat);
 145 #else
 146   ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,
 147                       &dostat);
 148 #endif
 149
 150   if (ret && dostat != -1)
 151     {
 152       dostat = 1;
 153 #ifdef _STATBUF_ST_RDEV
 154       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino,
 155                           save, &dostat);
 156 #else
 157       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino,
 158                           save, &dostat);
 159 #endif
 160     }
 161
 162   return ret;
 163 }
 164
 165 weak_alias (__ttyname_r, ttyname_r)