glibc/sysdeps/unix/bsd/unlockpt.c

/* Copyright (C) 1998 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 <stdlib.h>
#include <unistd.h>

#include "pty-internal.h"

/* Given a fd on a master pseudoterminal, clear a kernel lock so that
   the slave can be opened.  This is to avoid a race between opening the
   master and calling grantpt() to take possession of the slave.

   BSD doesn't have this lock, but what it does have is revoke(). */

int
unlockpt (fd)
     int fd;
{
  char buf[PTYNAMELEN];

  if (__ptsname_r (fd, buf, PTYNAMELEN))
    return -1;

  return revoke (buf);
}