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/* Copyright (C) 1998, 1999 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.

   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 <fcntl.h>

#include <string.h>

#include <unistd.h>

/* Prefix for master pseudo terminal nodes.  */

#define _PATH_PTY "/dev/pty"

/* Letters indicating a series of pseudo terminals.  */

#ifndef PTYNAME1

#define PTYNAME1 "pqrsPQRS"

#endif

const char _ptyname1[] = PTYNAME1;

/* Letters indicating the position within a series.  */

#ifndef PTYNAME2

#define PTYNAME2 "0123456789abcdefghijklmnopqrstuv";

#endif

const char _ptyname2[] = PTYNAME2;

/* Open a master pseudo terminal and return its file descriptor.  */

int

__getpt (void)

{

  char buf[sizeof (_PATH_PTY) + 2];

  const char *p, *q;

  char *s;

  memcpy (buf, _PATH_PTY, sizeof (_PATH_PTY));

  s = buf + strlen (buf);

  /* s[0] and s[1] will be filled in the loop.  */

  s[2] = '\0';

  for (p = _ptyname1; *p != '\0'; ++p)

    {

      s[0] = *p;

      for (q = _ptyname2; *q != '\0'; ++q)

        {

          int fd;

          s[1] = *q;

          fd = open (buf, O_RDWR);

          if (fd != -1)

            return fd;

          if (errno == ENOENT)

            return -1;

        }

    }

  errno = ENOENT;

  return -1;

}