.\" .\" Copyright (c) 2002 The FreeBSD Project, Inc. .\" All rights reserved. .\" .\" This software includes code contributed to the FreeBSD Project .\" by Ryan Younce of North Carolina State University. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the FreeBSD Project nor the names of its .\" contributors may be used to endorse or promote products derived from .\" this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS .\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT .\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A .\" PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT .\" OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED .\" TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR .\" PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF .\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING .\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS .\" SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc/stdlib/grantpt.3,v 1.3 2003/09/14 13:41:57 ru Exp $ .\" .Dd December 23, 2002 .Os .Dt GRANTPT 3 .Sh NAME .Nm grantpt , .Nm ptsname , .Nm unlockpt , .Nm posix_openpt .Nd pseudo-terminal access functions .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In stdlib.h .Ft int .Fn grantpt "int fildes" .Ft "char *" .Fn ptsname "int fildes" .Ft int .Fn unlockpt "int fildes" .In fcntl.h .Ft int .Fn posix_openpt "int mode" .Sh DESCRIPTION The .Fn grantpt , .Fn ptsname , .Fn unlockpt , and .Fn posix_openpt functions allow access to pseudo-terminal devices. The first three functions accept a file descriptor that references the master half of a pseudo-terminal pair. This file descriptor is created with .Fn posix_openpt . .Pp The .Fn grantpt function is used to establish ownership and permissions of the slave device counterpart to the master device specified with .Fa fildes . The slave device's ownership is set to the real user ID of the calling process, and the permissions are set to user readable-writable and group writable. The group owner of the slave device is also set to the group .Dq Li tty if it exists on the system; otherwise, it is left untouched. .Pp The .Fn ptsname function returns the full pathname of the slave device counterpart to the master device specified with .Fa fildes . This value can be used to subsequently open the appropriate slave after .Fn posix_openpt and .Fn grantpt have been called. .Pp The .Fn unlockpt function clears the lock held on the pseudo-terminal pair for the master device specified with .Fa fildes . .Pp The .Fn posix_openpt function opens the first available master pseudo-terminal device and returns a descriptor to it. The .Fa mode argument specifies the flags used for opening the device: .Bl -tag -width ".Dv O_NOCTTY" .It Dv O_RDWR Open for reading and writing. .It Dv O_NOCTTY If set, do not allow the terminal to become the controlling terminal for the calling process. .El .Sh RETURN VALUES .Rv -std grantpt unlockpt .Pp The .Fn ptsname function returns a pointer to the name of the slave device on success; otherwise a .Dv NULL pointer is returned and the global variable .Va errno is set to indicate the error. .Pp The .Fn posix_openpt function returns a file descriptor to the first available master pseudo-terminal device on success; otherwise \-1 is returned and the global variable .Va errno is set to indicate the error. .Sh ERRORS The .Fn grantpt , .Fn ptsname , and .Fn unlockpt functions may fail and set .Va errno to: .Bl -tag -width Er .It Bq Er EINVAL .Fa fildes is not a master pseudo-terminal device. .El .Pp In addition, the .Fn grantpt function may set .Va errno to: .Bl -tag -width Er .It Bq Er EACCES The slave pseudo-terminal device could not be accessed. .El .Pp The .Fn posix_openpt function may fail and set .Va errno to: .Bl -tag -width Er .It Bq Er EINVAL .Fa mode consists of an invalid mode bit. .It Bq Er EAGAIN The system has no available pseudo-terminal devices. .El .Pp The .Fn grantpt , .Fn ptsname , and .Fn unlockpt functions may also fail and set .Va errno for any of the errors specified for the .Xr fstat 2 system call. .Pp The .Fn posix_openpt function may also fail and set .Va errno for any of the errors specified for the .Xr open 2 system call. .Sh SEE ALSO .Xr open 2 , .Xr pty 4 , .Xr tty 4 .Sh STANDARDS The .Fn grantpt , .Fn ptsname , .Fn unlockpt , and .Fn posix_openpt functions conform to .St -p1003.1-2001 . .Sh HISTORY The .Fn grantpt , .Fn ptsname , .Fn unlockpt , and .Fn posix_openpt functions appeared in .Fx 5.0 . .Sh NOTES The purpose of the .Fn unlockpt function has no meaning in .Fx . .Pp The flag .Dv O_NOCTTY is included for compatibility; in .Fx , opening a terminal does not cause it to become a process's controlling terminal.