/* Determine name of the slave side of a pseudo-terminal.
   Copyright (C) 1998, 2002, 2010-2012 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#include <stdlib.h>

#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#ifdef _LIBC
# include <paths.h>
#else
# ifndef _PATH_TTY
#  define _PATH_TTY "/dev/tty"
# endif
# ifndef _PATH_DEV
#  define _PATH_DEV "/dev/"
# endif

# define __set_errno(e) errno = (e)
# define __isatty isatty
# define __stat stat
# define __ttyname_r ttyname_r
# define __ptsname_r ptsname_r

#endif


/* Store at most BUFLEN characters of the pathname of the slave pseudo
   terminal associated with the master FD is open on in BUF.
   Return 0 on success, otherwise an error number.  */
int
__ptsname_r (int fd, char *buf, size_t buflen)
{
  int save_errno = errno;
  int err;
  struct stat st;

  if (buf == NULL)
    {
      __set_errno (EINVAL);
      return EINVAL;
    }

  if (!__isatty (fd))
    /* We rely on isatty to set errno properly (i.e. EBADF or ENOTTY).  */
    return errno;

  if (buflen < strlen (_PATH_TTY) + 3)
    {
      __set_errno (ERANGE);
      return ERANGE;
    }

  err = __ttyname_r (fd, buf, buflen);
  if (err != 0)
    {
      __set_errno (err);
      return errno;
    }

  buf[sizeof (_PATH_DEV) - 1] = 't';

  if (__stat (buf, &st) < 0)
    return errno;

  __set_errno (save_errno);
  return 0;
}