.\" $NetBSD: grantpt.3,v 1.4 2008/04/30 13:10:51 martin Exp $
.\"
.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
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.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Christos Zoulas.
.\"
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.Dd May 25, 2004
.Dt GRANTPT 3
.Os
.Sh NAME
.Nm grantpt
.Nd grant access to a slave pseudo-terminal device
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn grantpt "int fildes"
.Sh DESCRIPTION
The
.Fn grantpt
function changes the mode and ownership of the slave pseudo-terminal device
that corresponds to the master pseudo-terminal device associated with
.Fa fildes
to be owned by the real user id of the calling process, group id of
.Dv tty .
The permissions are set to readable and writable by owner, and writable by
group.
If the slave pseudo-terminal device was being accessed by other file
descriptors at the time, all such access will be revoked.
.Sh RETURN VALUES
If successful,
.Fn grantpt
returns 0; otherwise a value of \-1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn grantpt
function will fail if:
.Bl -tag -width Er
.It Bq Er EACCESS
the corresponding pseudo-terminal device could not be accessed.
.It Bq Er EBADF
.Fa fildes
is not a valid descriptor.
.It Bq Er EINVAL
.Fa fildes
is not associated with a master pseudo-terminal device.
.El
.Sh NOTES
Setting the group to
.Dv tty
and revoking accesses by other file descriptors are
.Nx
extensions.
Calling
.Fn grantpt
is equivalent to:
.Bd -literal
	ioctl(fildes, TIOCGRANTPT, 0);
.Ed
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr posix_openpt 3 ,
.Xr ptsname 3 ,
.Xr unlockpt 3
.Sh STANDARDS
The
.Fn grantpt
function conforms to
.St -p1003.1-2001 .
Its first release was in
.St -xpg4.2 .