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/* Copyright (C) 1991, 1992, 1993, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
char *__ttyname = NULL;
/* Return the pathname of the terminal FD is open on, or NULL on errors.
The returned storage is good only until the next call to this function. */
char *
ttyname (fd)
int fd;
{
static const char dev[] = "/dev";
static char *name;
static size_t namelen = 0;
struct stat st;
dev_t mydev;
ino_t myino;
DIR *dirstream;
struct dirent dirbuf, *d;
int save = errno;
if (!__isatty (fd))
return NULL;
if (fstat (fd, &st) < 0)
return NULL;
mydev = st.st_dev;
myino = st.st_ino;
dirstream = opendir (dev);
if (dirstream == NULL)
return NULL;
while (__readdir_r (dirstream, &dirbuf, &d) >= 0)
if ((ino_t) d->d_fileno == myino)
{
size_t dlen = _D_ALLOC_NAMLEN (d);
if (sizeof (dev) + dlen > namelen)
{
free (name);
namelen = 2 * (sizeof (dev) + dlen); /* Big enough. */
name = malloc (namelen);
if (! name)
return NULL;
(void) memcpy (name, dev, sizeof (dev) - 1);
name[sizeof (dev) - 1] = '/';
}
(void) memcpy (&name[sizeof (dev)], d->d_name, dlen);
if (stat (name, &st) == 0 && st.st_dev == mydev)
{
(void) closedir (dirstream);
__ttyname = name;
__set_errno (save);
return name;
}
}
(void) closedir (dirstream);
__set_errno (save);
return NULL;
}
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