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: src/lib/libc/stdlib/ptsname.3,v 1.4 2010/04/14 19:08:06 uqs Exp $ 33.\" 34.Dd September 10, 2009 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 3 63or by calling 64.Xr open 2 65on 66.Pa /dev/ptmx . 67.Pp 68The 69.Fn grantpt 70function is used to establish ownership and permissions 71of the slave device counterpart to the master device 72specified with 73.Fa fildes . 74The slave device's ownership is set to the real user ID 75of the calling process, and the permissions are set to 76user readable-writable and group writable. 77The group owner of the slave device is also set to the 78group 79.Dq Li tty . 80.Pp 81The 82.Fn ptsname 83function returns the full pathname of the slave device 84counterpart to the master device specified with 85.Fa fildes . 86This value can be used 87to subsequently open the appropriate slave after 88.Xr posix_openpt 3 89and 90.Fn grantpt 91have been called. 92.Pp 93The 94.Fn unlockpt 95function clears the lock held on the pseudo-terminal pair 96for the master device specified with 97.Fa fildes . 98.Sh RETURN VALUES 99.Rv -std grantpt unlockpt 100.Pp 101The 102.Fn ptsname 103function returns a pointer to the name 104of the slave device on success; otherwise a 105.Dv NULL 106pointer is returned. 107.Sh ERRORS 108The 109.Fn grantpt 110and 111.Fn unlockpt 112functions may fail and set 113.Va errno 114to: 115.Bl -tag -width Er 116.It Bq Er EBADF 117.Fa fildes 118is not a valid open file descriptor. 119.It Bq Er EINVAL 120.Fa fildes 121is not a master pseudo-terminal device. 122.El 123.Pp 124In addition, the 125.Fn grantpt 126function may set 127.Va errno 128to: 129.Bl -tag -width Er 130.It Bq Er EACCES 131The slave pseudo-terminal device could not be accessed. 132.El 133.Sh SEE ALSO 134.Xr posix_openpt 3 , 135.Xr tty 4 136.Sh STANDARDS 137The 138.Fn ptsname 139function conforms to 140.St -p1003.1-2008 . 141.Pp 142This implementation of 143.Fn grantpt 144and 145.Fn unlockpt 146does not conform to 147.St -p1003.1-2008 , 148because it depends on 149.Xr posix_openpt 3 150to create the pseudo-terminal device with proper permissions in place. 151It only validates whether 152.Fa fildes 153is a valid pseudo-terminal master device. 154Future revisions of the specification will likely allow this behaviour, 155as stated by the Austin Group. 156.Sh HISTORY 157The 158.Fn grantpt , 159.Fn ptsname 160and 161.Fn unlockpt 162functions appeared in 163.Dx 2.3 . 164