/* Copyright (C) 1991-2018 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 Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#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>

#ifndef MIN

# define MIN(a, b) ((a) < (b) ? (a) : (b))

#endif

static const char dev[] = "/dev";

static int getttyname_r (int fd, char *buf, size_t buflen,

			 dev_t mydev, ino_t myino, int save,

			 int *dostat) __THROW;

static int

getttyname_r (int fd, char *buf, size_t buflen, dev_t mydev, ino_t myino,

	      int save, int *dostat)

{

  struct stat st;

  DIR *dirstream;

  struct dirent *d;

  dirstream = __opendir (dev);

  if (dirstream == NULL)

    {

      *dostat = -1;

      return errno;

    }

  while ((d = __readdir (dirstream)) != NULL)

    if (((ino_t) d->d_fileno == myino || *dostat)

	&& strcmp (d->d_name, "stdin")

	&& strcmp (d->d_name, "stdout")

	&& strcmp (d->d_name, "stderr"))

      {

	char *cp;

	size_t needed = _D_EXACT_NAMLEN (d) + 1;

	if (needed > buflen)

	  {

	    *dostat = -1;

	    (void) __closedir (dirstream);

	    __set_errno (ERANGE);

	    return ERANGE;

	  }

	cp = __stpncpy (&buf[sizeof (dev)], d->d_name, needed);

	cp[0] = '\0';

	if (stat (buf, &st) == 0

#ifdef _STATBUF_ST_RDEV

	    && S_ISCHR (st.st_mode) && st.st_rdev == mydev

#else

	    && (ino_t) d->d_fileno == myino && st.st_dev == mydev

#endif

	   )

	  {

	    (void) __closedir (dirstream);

	    __set_errno (save);

	    return 0;

	  }

      }

  (void) __closedir (dirstream);

  __set_errno (save);

  /* It is not clear what to return in this case.  `isatty' says FD

     refers to a TTY but no entry in /dev has this inode.  */

  return ENOTTY;

}

/* Store at most BUFLEN character of the pathname of the terminal FD is

   open on in BUF.  Return 0 on success,  otherwise an error number.  */

int

__ttyname_r (int fd, char *buf, size_t buflen)

{

  struct stat st;

  int dostat = 0;

  int save = errno;

  int ret;

  /* Test for the absolute minimal size.  This makes life easier inside

     the loop.  */

  if (!buf)

    {

      __set_errno (EINVAL);

      return EINVAL;

    }

  if (buflen < (int) (sizeof (dev) + 1))

    {

      __set_errno (ERANGE);

      return ERANGE;

    }

  if (!__isatty (fd))

    {

      __set_errno (ENOTTY);

      return ENOTTY;

    }

  if (fstat (fd, &st) < 0)

    return errno;

  /* Prepare the result buffer.  */

  memcpy (buf, dev, sizeof (dev) - 1);

  buf[sizeof (dev) - 1] = '/';

  buflen -= sizeof (dev);

#ifdef _STATBUF_ST_RDEV

  ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,

		      &dostat);

#else

  ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,

		      &dostat);

#endif

  if (ret && dostat != -1)

    {

      dostat = 1;

#ifdef _STATBUF_ST_RDEV

      ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino,

			  save, &dostat);

#else

      ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino,

			  save, &dostat);

#endif

    }

  return ret;

}

weak_alias (__ttyname_r, ttyname_r)