sysdeps/posix/ttyname_r.c

   1 /* Copyright (C) 1991,92,93,95,96,97,98,2004 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  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 <unistd.h>
  26 #include <string.h>
  27 #include <stdlib.h>
  28
  29 #ifndef MIN
  30 # define MIN(a, b) ((a) < (b) ? (a) : (b))
  31 #endif
  32
  33 static const char dev[] = "/dev";
  34
  35 static int getttyname_r (int fd, char *buf, size_t buflen,
  36                          dev_t mydev, ino_t myino, int save,
  37                          int *dostat) __THROW internal_function;
  38
  39 static int
  40 internal_function
  41 getttyname_r (fd, buf, buflen, mydev, myino, save, dostat)
  42      int fd;
  43      char *buf;
  44      size_t buflen;
  45      dev_t mydev;
  46      ino_t myino;
  47      int save;
  48      int *dostat;
  49 {
  50   struct stat st;
  51   DIR *dirstream;
  52   struct dirent *d;
  53
  54   dirstream = __opendir (dev);
  55   if (dirstream == NULL)
  56     {
  57       *dostat = -1;
  58       return errno;
  59     }
  60
  61   while ((d = __readdir (dirstream)) != NULL)
  62     if (((ino_t) d->d_fileno == myino || *dostat)
  63         && strcmp (d->d_name, "stdin")
  64         && strcmp (d->d_name, "stdout")
  65         && strcmp (d->d_name, "stderr"))
  66       {
  67         char *cp;
  68         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  69
  70         if (needed > buflen)
  71           {
  72             *dostat = -1;
  73             (void) __closedir (dirstream);
  74             __set_errno (ERANGE);
  75             return ERANGE;
  76           }
  77
  78         cp = __stpncpy (&buf[sizeof (dev)], d->d_name, needed);
  79         cp[0] = '\0';
  80
  81         if (stat (buf, &st) == 0
  82 #ifdef _STATBUF_ST_RDEV
  83             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  84 #else
  85             && (ino_t) d->d_fileno == myino && st.st_dev == mydev
  86 #endif
  87            )
  88           {
  89             (void) __closedir (dirstream);
  90             __set_errno (save);
  91             return 0;
  92           }
  93       }
  94
  95   (void) __closedir (dirstream);
  96   __set_errno (save);
  97   /* It is not clear what to return in this case.  `isatty' says FD
  98      refers to a TTY but no entry in /dev has this inode.  */
  99   return ENOTTY;
 100 }
 101
 102 /* Store at most BUFLEN character of the pathname of the terminal FD is
 103    open on in BUF.  Return 0 on success,  otherwise an error number.  */
 104 int
 105 __ttyname_r (fd, buf, buflen)
 106      int fd;
 107      char *buf;
 108      size_t buflen;
 109 {
 110   struct stat st;
 111   int dostat = 0;
 112   int save = errno;
 113   int ret;
 114
 115   /* Test for the absolute minimal size.  This makes life easier inside
 116      the loop.  */
 117   if (!buf)
 118     {
 119       __set_errno (EINVAL);
 120       return EINVAL;
 121     }
 122
 123   if (buflen < (int) (sizeof (dev) + 1))
 124     {
 125       __set_errno (ERANGE);
 126       return ERANGE;
 127     }
 128
 129   if (!__isatty (fd))
 130     {
 131       __set_errno (ENOTTY);
 132       return ENOTTY;
 133     }
 134
 135   if (fstat (fd, &st) < 0)
 136     return errno;
 137
 138   /* Prepare the result buffer.  */
 139   memcpy (buf, dev, sizeof (dev) - 1);
 140   buf[sizeof (dev) - 1] = '/';
 141   buflen -= sizeof (dev);
 142
 143 #ifdef _STATBUF_ST_RDEV
 144   ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,
 145                       &dostat);
 146 #else
 147   ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,
 148                       &dostat);
 149 #endif
 150
 151   if (ret && dostat != -1)
 152     {
 153       dostat = 1;
 154 #ifdef _STATBUF_ST_RDEV
 155       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino,
 156                           save, &dostat);
 157 #else
 158       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino,
 159                           save, &dostat);
 160 #endif
 161     }
 162
 163   return ret;
 164 }
 165
 166 weak_alias (__ttyname_r, ttyname_r)