2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
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5.9 KiB
Groff
221 lines
5.9 KiB
Groff
.\" $NetBSD: ioctl.2,v 1.23 2010/12/19 22:19:27 wiz Exp $
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.\"
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.\" 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. 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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.Dd December 19, 2010
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.Dt IOCTL 2
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.Os
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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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.In 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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An
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.Fn 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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.Dq out ,
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or
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.Dq inout
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parameter, and the size of the first variadic argument
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in bytes.
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Note that there can be only one variadic argument but cannot be represented as
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a
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.Ft "void *"
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argument in the prototype because this would require a cast to pass integral
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types without warnings.
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Macros and defines used in specifying an
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.Fn ioctl
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.Fa request
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are located in the header
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.In sys/ioctl.h .
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.Sh GENERIC IOCTLS
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Some ioctls are applicable to any file descriptor.
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These include:
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.Bl -tag -width "xxxxxx"
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.It Dv FIOCLEX
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Set close-on-exec flag.
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The file will be closed when
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.Xr exec 3
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is invoked
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(This is equivalent to
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.Fn fcntl
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.Dv F_SETFD
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.Dv FD_CLOEXEC
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and the
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.Fn fcntl
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form should be preferred).
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.It Dv FIONCLEX
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Clear close-on-exec flag.
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The file will remain open across
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.Xr exec 3
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(This is equivalent to
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.Fn fcntl
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.Dv F_SETFD
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.Dv 0
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and the
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.Fn fcntl
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form should be preferred).
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.El
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.Pp
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Some generic ioctls are not implemented for all types of file
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descriptors.
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These include:
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.Bl -tag -width "xxxxxx"
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.It Dv FIONREAD "int"
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Get the number of bytes that are immediately available for reading.
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.It Dv FIONWRITE "int"
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Get the number of bytes in the descriptor's send queue.
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These bytes are data which has been written to the descriptor but
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which are being held by the kernel for further processing.
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The nature of the required processing depends on the underlying device.
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For tty devices, these bytes are typically queued for delivery
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to the tty hardware.
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For TCP sockets, these bytes have not yet been acknowledged by the
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other side of the connection.
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For files, this operation always returns zero as files do not have
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send queues.
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.It Dv FIONSPACE "int"
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Get the free space in the descriptor's send queue.
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This value is the size of the send queue minus the number of bytes
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being held in the queue.
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Note: while this value represents the number of bytes that may be
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added to the queue, other resource limitations may cause a write
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not larger than the send queue's space to be blocked.
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One such limitation would be a lack of network buffers for a write
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to a network connection.
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.It Dv FIONBIO "int"
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Set non-blocking I/O mode if the argument is non-zero.
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In non-blocking mode,
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.Xr read 2
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or
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.Xr write 2
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calls return
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.Dv \-1
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and set
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.Va errno
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to
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.Er EAGAIN
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immediately when no data is available
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(This is equivalent to
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.Fn fcntl
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.Dv F_SETFL
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.Dv O_NONBLOCK
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and the
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.Fn fcntl
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form should be preferred).
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.It Dv FIOASYNC "int"
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Set asynchronous I/O mode if the argument is non-zero
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(This is equivalent to
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.Fn fcntl
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.Dv F_SETFL
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.Dv O_ASYNC
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and the
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.Fn fcntl
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form should be preferred).
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In asynchronous mode, the process or process group specified by
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.Dv FIOSETOWN
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will start receiving
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.Dv SIGIO
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signals when data is available.
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The
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.Dv SIGIO
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signal will be delivered when data is available on the file
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descriptor.
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.It Dv FIOSETOWN, FIOGETOWN "int"
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Set/get the process or the process group (if negative) that should receive
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.Dv SIGIO
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signals when data is available
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(This is equivalent to
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.Fn fcntl
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.Dv F_SETOWN
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.Ft pid_t
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and the
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.Ft fcntl
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form should be preferred).
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.El
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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 Er
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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 EFAULT
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.Fa argp
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points outside the process's allocated address space.
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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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.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; or
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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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.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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