147 lines
3.7 KiB
Groff
147 lines
3.7 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)ioctl.2 8.2 (Berkeley) 12/11/93
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 11, 1993
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.Dt IOCTL 2
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.Os BSD 4
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.Sh NAME
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.Nm ioctl
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.Nd control device
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <sys/ioctl.h>
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.Ft int
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.Fn ioctl "int d" "unsigned long request" ...
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.Sh DESCRIPTION
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The
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.Fn ioctl
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function manipulates the underlying device parameters of special files.
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In particular, many operating
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characteristics of character special files (e.g. terminals)
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may be controlled with
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.Fn ioctl
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requests.
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The argument
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.Fa d
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must be an open file descriptor.
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.Pp
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The third argument to
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.Nm
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is traditionally named
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.Ar "char *argp" .
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Most uses of
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.Nm
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in
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.Fx 3.0
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however, require the third argument to be a
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.Ar caddr_t
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or an
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.Ar int .
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.Pp
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An ioctl
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.Fa request
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has encoded in it whether the argument is an
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.Dq in
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parameter
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or
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.Dq out
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parameter, and the size of the argument
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.Fa argp
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in bytes.
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Macros and defines used in specifying an ioctl
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.Fa request
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are located in the file
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.Ao Pa sys/ioctl.h Ac .
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.Sh IMPLEMENTATION NOTES
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.Pp
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In the non-threaded library
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.Fn ioctl
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is implemented as the
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.Va ioctl
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syscall.
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.Pp
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In the threaded library, the
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.Va ioctl
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syscall is assembled to
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.Fn _thread_sys_ioctl
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and
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.Fn ioctl
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is implemented as a function which locks
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.Va d
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for read and write, then calls
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.Fn _thread_sys_ioctl .
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Before returning,
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.Fn ioctl
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unlocks
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.Va d .
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.Sh RETURN VALUES
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If an error has occurred, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn Ioctl
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will fail if:
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.Bl -tag -width [ENOTTY]
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.It Bq Er EBADF
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.Fa d
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is not a valid descriptor.
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.It Bq Er ENOTTY
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.Fa d
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is not associated with a character
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special device.
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.It Bq Er ENOTTY
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The specified request does not apply to the kind
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of object that the descriptor
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.Fa d
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references.
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.It Bq Er EINVAL
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.Fa Request
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or
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.Fa argp
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is not valid.
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.El
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.Sh SEE ALSO
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.Xr mt 1 ,
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.Xr execve 2 ,
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.Xr fcntl 2 ,
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.Xr intro 4 ,
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.Xr tty 4
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.Sh HISTORY
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An
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.Fn ioctl
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function call appeared in
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.At v7 .
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