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/* 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 <sys/ioctl.h>
#include <termios.h>
#include <errno.h>
#include <stdlib.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. */
int
unlockpt (fd)
int fd __attribute__ ((unused));
{
#ifdef TIOCSPTLCK
int serrno = errno;
int unlock = 0;
if (ioctl (fd, TIOCSPTLCK, &unlock))
{
if(errno == EINVAL)
{
__set_errno (serrno);
return 0;
}
else
return -1;
}
#else
/* On pre-/dev/ptmx kernels this function should be a no-op. */
return 0;
#endif
}
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