sysdeps/posix/ttyname.c

   1 /* Copyright (C) 1991, 92, 93, 96, 97, 98 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 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 char *__ttyname = NULL;
  30
  31 static char * getttyname __P ((int fd, dev_t mydev, ino_t myino,
  32                                int save, int *dostat)) internal_function;
  33
  34 static char *
  35 internal_function
  36 getttyname (fd, mydev, myino, save, dostat)
  37      int fd;
  38      dev_t mydev;
  39      ino_t myino;
  40      int save;
  41      int *dostat;
  42 {
  43   static const char dev[] = "/dev";
  44   static char *name;
  45   static size_t namelen = 0;
  46   struct stat st;
  47   DIR *dirstream;
  48   struct dirent *d;
  49
  50   dirstream = opendir (dev);
  51   if (dirstream == NULL)
  52     {
  53       *dostat = -1;
  54       return NULL;
  55     }
  56
  57   while ((d = readdir (dirstream)) != NULL)
  58     if (((ino_t) d->d_fileno == myino || *dostat)
  59         && strcmp (d->d_name, "stdin")
  60         && strcmp (d->d_name, "stdout")
  61         && strcmp (d->d_name, "stderr"))
  62       {
  63         size_t dlen = _D_ALLOC_NAMLEN (d);
  64         if (sizeof (dev) + dlen > namelen)
  65           {
  66             free (name);
  67             namelen = 2 * (sizeof (dev) + dlen); /* Big enough.  */
  68             name = malloc (namelen);
  69             if (! name)
  70               {
  71                 *dostat = -1;
  72                 /* Perhaps it helps to free the directory stream buffer.  */
  73                 (void) closedir (dirstream);
  74                 return NULL;
  75               }
  76             *((char *) __mempcpy (name, dev, sizeof (dev) - 1)) = '/';
  77           }
  78         (void) __mempcpy (&name[sizeof (dev)], d->d_name, dlen);
  79         if (stat (name, &st) == 0
  80 #ifdef _STATBUF_ST_RDEV
  81             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  82 #else
  83             && (ino_t) d->d_fileno == myino && st.st_dev == mydev
  84 #endif
  85            )
  86           {
  87             (void) closedir (dirstream);
  88             __ttyname = name;
  89             __set_errno (save);
  90             return name;
  91           }
  92       }
  93
  94   (void) closedir (dirstream);
  95   __set_errno (save);
  96   return NULL;
  97 }
  98
  99 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 100    The returned storage is good only until the next call to this function.  */
 101 char *
 102 ttyname (fd)
 103      int fd;
 104 {
 105   struct stat st;
 106   int dostat = 0;
 107   char *name;
 108   int save = errno;
 109
 110   if (!__isatty (fd))
 111     return NULL;
 112
 113   if (fstat (fd, &st) < 0)
 114     return NULL;
 115
 116 #ifdef _STATBUF_ST_RDEV
 117   name = getttyname (fd, st.st_rdev, st.st_ino, save, &dostat);
 118 #else
 119   name = getttyname (fd, st.st_dev, st.st_ino, save, &dostat);
 120 #endif
 121
 122   if (!name && dostat != -1)
 123     {
 124       dostat = 1;
 125 #ifdef _STATBUF_ST_RDEV
 126       name = getttyname (fd, st.st_rdev, st.st_ino, save, &dostat);
 127 #else
 128       name = getttyname (fd, st.st_dev, st.st_ino, save, &dostat);
 129 #endif
 130     }
 131
 132   return name;
 133 }