169 lines
4.1 KiB
Groff
169 lines
4.1 KiB
Groff
.\" $NetBSD: ptsname.3,v 1.10 2017/07/03 21:32:50 wiz Exp $
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.\"
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.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd January 7, 2014
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.Dt PTSNAME 3
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.Os
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.Sh NAME
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.Nm ptsname ,
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.Nm ptsname_r
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.Nd get the pathname of the slave pseudo-terminal device
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft char *
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.Fn ptsname "int masterfd"
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.Ft char *
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.Fn ptsname_r "int masterfd" "char *buf" "size_t buflen"
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.Sh DESCRIPTION
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The
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.Fn ptsname
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function returns the pathname of the slave pseudo-terminal device
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that corresponds to the master pseudo-terminal device associated with
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.Fa masterfd .
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The
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.Fn ptsname
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function is not reentrant or thread-safe.
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.Pp
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The
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.Fn ptsname_r
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function
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places the pathname of the slave pseudo-terminal device that corresponds
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to the master pseudo-terminal device associated with
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.Fa masterfd
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int the
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.Fa buf
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argument copying up to
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.Fa buflen
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characters.
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The
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.Fa buf
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is always
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.Dv NUL
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terminated.
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.Sh RETURN VALUES
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If successful,
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.Fn ptsname
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returns a pointer to a nul-terminated string containing the pathname
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of the slave pseudo-terminal device.
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If an error occurs
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.Fn ptsname
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will return
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.Dv NULL
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and
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.Va errno
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is set to indicate the error.
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.Pp
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If successful,
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.Fn ptsname_r
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places a nul-terminated string containing the pathname
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of the slave pseudo-terminal device
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in
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.Fa buf
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and returns
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.Dv 0 .
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If an error occurs
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.Fn ptsname_r
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will return
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an error number number indicating what went wrong.
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.Sh ERRORS
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The
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.Fn ptsname
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and
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.Fn ptsname_r
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functions will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCESS
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the corresponding pseudo-terminal device could not be accessed.
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.It Bq Er EBADF
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.Fa masterfd
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is not a valid descriptor.
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.It Bq Er EINVAL
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.Fa masterfd
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is not associated with a master pseudo-terminal device.
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.El
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.Pp
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In addition the
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.Fn ptsname_r
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function
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will return:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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the
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.Fa buf
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argument is
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.Dv NULL .
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.It Bq Er ERANGE
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the name of the pseudo-terminal is longer than
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.Fa bufsiz
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characters plus the terminating
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.Dv NUL .
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.El
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.Sh NOTES
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The error returns of
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.Fn ptsname
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are a
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.Nx
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extension.
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The
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.Fn ptsname
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function is equivalent to:
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.Bd -literal
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struct ptmget pm;
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return ioctl(masterfd, TIOCPTSNAME, &pm) == -1 ? NULL : pm.sn;
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.Ed
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.Pp
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Both the
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.Fn ptsname
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and
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.Fn ptsname_r
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functions will also return the name of the slave pseudo-terminal if a file
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descriptor to the slave pseudo-terminal is passed to
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.Fa masterfd .
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.Pp
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This is a convenient extension because it allows one to use the file descriptor
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obtained by
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.Xr open 2
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.Pa /dev/tty
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to obtain the name of the pseudo-terminal for the current process.
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr open 2 ,
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.Xr grantpt 3 ,
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.Xr posix_openpt 3 ,
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.Xr unlockpt 3
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.Sh STANDARDS
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The
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.Fn ptsname
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function conforms to
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.St -p1003.1-2001 .
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Its first release was in
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.St -xpg4.2 .
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