sysdeps/posix/ttyname.c

   1 /* Copyright (C) 1991,92,93,96,97,98,2000,2002 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 char *__ttyname;
  30
  31 static char *getttyname (int fd, dev_t mydev, ino_t myino,
  32                          int save, int *dostat) internal_function;
  33
  34
  35 libc_freeres_ptr (static char *getttyname_name);
  36
  37 static char *
  38 internal_function
  39 getttyname (fd, mydev, myino, save, dostat)
  40      int fd;
  41      dev_t mydev;
  42      ino_t myino;
  43      int save;
  44      int *dostat;
  45 {
  46   static const char dev[] = "/dev";
  47   static size_t namelen;
  48   struct stat st;
  49   DIR *dirstream;
  50   struct dirent *d;
  51
  52   dirstream = __opendir (dev);
  53   if (dirstream == NULL)
  54     {
  55       *dostat = -1;
  56       return NULL;
  57     }
  58
  59   while ((d = __readdir (dirstream)) != NULL)
  60     if (((ino_t) d->d_fileno == myino || *dostat)
  61         && strcmp (d->d_name, "stdin")
  62         && strcmp (d->d_name, "stdout")
  63         && strcmp (d->d_name, "stderr"))
  64       {
  65         size_t dlen = _D_ALLOC_NAMLEN (d);
  66         if (sizeof (dev) + dlen > namelen)
  67           {
  68             free (getttyname_name);
  69             namelen = 2 * (sizeof (dev) + dlen); /* Big enough.  */
  70             getttyname_name = malloc (namelen);
  71             if (! getttyname_name)
  72               {
  73                 *dostat = -1;
  74                 /* Perhaps it helps to free the directory stream buffer.  */
  75                 (void) __closedir (dirstream);
  76                 return NULL;
  77               }
  78             *((char *) __mempcpy (getttyname_name, dev, sizeof (dev) - 1))
  79               = '/';
  80           }
  81         (void) __mempcpy (&getttyname_name[sizeof (dev)], d->d_name, dlen);
  82         if (stat (getttyname_name, &st) == 0
  83 #ifdef _STATBUF_ST_RDEV
  84             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  85 #else
  86             && (ino_t) d->d_fileno == myino && st.st_dev == mydev
  87 #endif
  88            )
  89           {
  90             (void) __closedir (dirstream);
  91             __ttyname = getttyname_name;
  92             __set_errno (save);
  93             return getttyname_name;
  94           }
  95       }
  96
  97   (void) __closedir (dirstream);
  98   __set_errno (save);
  99   return NULL;
 100 }
 101
 102 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 103    The returned storage is good only until the next call to this function.  */
 104 char *
 105 ttyname (fd)
 106      int fd;
 107 {
 108   struct stat st;
 109   int dostat = 0;
 110   char *name;
 111   int save = errno;
 112
 113   if (!__isatty (fd))
 114     return NULL;
 115
 116   if (fstat (fd, &st) < 0)
 117     return NULL;
 118
 119 #ifdef _STATBUF_ST_RDEV
 120   name = getttyname (fd, st.st_rdev, st.st_ino, save, &dostat);
 121 #else
 122   name = getttyname (fd, st.st_dev, st.st_ino, save, &dostat);
 123 #endif
 124
 125   if (!name && dostat != -1)
 126     {
 127       dostat = 1;
 128 #ifdef _STATBUF_ST_RDEV
 129       name = getttyname (fd, st.st_rdev, st.st_ino, save, &dostat);
 130 #else
 131       name = getttyname (fd, st.st_dev, st.st_ino, save, &dostat);
 132 #endif
 133     }
 134
 135   return name;
 136 }