1.\" 2.\" Copyright (c) 2002 The FreeBSD Project, Inc. 3.\" All rights reserved. 4.\" 5.\" This software includes code contributed to the FreeBSD Project 6.\" by Ryan Younce of North Carolina State University. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the FreeBSD Project nor the names of its 17.\" contributors may be used to endorse or promote products derived from 18.\" this software without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS 21.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 23.\" PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT 24.\" OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 26.\" TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 27.\" PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 28.\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 29.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 30.\" SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.\" $FreeBSD$ 33.\" 34.Dd August 20, 2008 35.Dt PTSNAME 3 36.Os 37.Sh NAME 38.Nm grantpt , 39.Nm ptsname , 40.Nm unlockpt 41.Nd pseudo-terminal access functions 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In stdlib.h 46.Ft int 47.Fn grantpt "int fildes" 48.Ft "char *" 49.Fn ptsname "int fildes" 50.Ft int 51.Fn unlockpt "int fildes" 52.Sh DESCRIPTION 53The 54.Fn grantpt , 55.Fn ptsname , 56and 57.Fn unlockpt 58functions allow access to pseudo-terminal devices. 59These three functions accept a file descriptor that references the 60master half of a pseudo-terminal pair. 61This file descriptor is created with 62.Xr posix_openpt 2 . 63.Pp 64The 65.Fn grantpt 66function is used to establish ownership and permissions 67of the slave device counterpart to the master device 68specified with 69.Fa fildes . 70The slave device's ownership is set to the real user ID 71of the calling process, and the permissions are set to 72user readable-writable and group writable. 73The group owner of the slave device is also set to the 74group 75.Dq Li tty . 76.Pp 77The 78.Fn ptsname 79function returns the full pathname of the slave device 80counterpart to the master device specified with 81.Fa fildes . 82This value can be used 83to subsequently open the appropriate slave after 84.Xr posix_openpt 2 85and 86.Fn grantpt 87have been called. 88.Pp 89The 90.Fn unlockpt 91function clears the lock held on the pseudo-terminal pair 92for the master device specified with 93.Fa fildes . 94.Sh RETURN VALUES 95.Rv -std grantpt unlockpt 96.Pp 97The 98.Fn ptsname 99function returns a pointer to the name 100of the slave device on success; otherwise a 101.Dv NULL 102pointer is returned. 103.Sh ERRORS 104The 105.Fn grantpt 106and 107.Fn unlockpt 108functions may fail and set 109.Va errno 110to: 111.Bl -tag -width Er 112.It Bq Er EBADF 113.Fa fildes 114is not a valid open file descriptor. 115.It Bq Er EINVAL 116.Fa fildes 117is not a master pseudo-terminal device. 118.El 119.Pp 120In addition, the 121.Fn grantpt 122function may set 123.Va errno 124to: 125.Bl -tag -width Er 126.It Bq Er EACCES 127The slave pseudo-terminal device could not be accessed. 128.El 129.Sh SEE ALSO 130.Xr posix_openpt 2 , 131.Xr pts 4 , 132.Xr tty 4 133.Sh STANDARDS 134The 135.Fn ptsname 136function conforms to 137.St -p1003.1-2008 . 138.Pp 139This implementation of 140.Fn grantpt 141and 142.Fn unlockpt 143does not conform to 144.St -p1003.1-2008 , 145because it depends on 146.Xr posix_openpt 2 147to create the pseudo-terminal device with proper permissions in place. 148It only validates whether 149.Fa fildes 150is a valid pseudo-terminal master device. 151Future revisions of the specification will likely allow this behaviour, 152as stated by the Austin Group. 153.Sh HISTORY 154The 155.Fn grantpt , 156.Fn ptsname 157and 158.Fn unlockpt 159functions appeared in 160.Fx 5.0 . 161