154 lines
3.9 KiB
Groff
154 lines
3.9 KiB
Groff
.\" $NetBSD: uiomove.9,v 1.18.8.2 2019/09/05 08:19:41 martin Exp $
|
|
.\"
|
|
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION OR 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.
|
|
.\"
|
|
.Dd April 26, 2010
|
|
.Dt UIOMOVE 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm uiomove
|
|
.Nd move data described by a struct uio
|
|
.Sh SYNOPSIS
|
|
.In sys/systm.h
|
|
.Ft int
|
|
.Fn uiomove "void *buf" "size_t n" "struct uio *uio"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn uiomove
|
|
function copies up to
|
|
.Fa n
|
|
bytes between the kernel-space address pointed
|
|
to by
|
|
.Fa buf
|
|
and the addresses described by
|
|
.Fa uio ,
|
|
which may be in user-space or kernel-space.
|
|
.Pp
|
|
The
|
|
.Fa uio
|
|
argument is a pointer to a
|
|
.Va struct uio
|
|
as defined by
|
|
.In sys/uio.h :
|
|
.Bd -literal -offset indent
|
|
struct uio {
|
|
struct iovec *uio_iov;
|
|
int uio_iovcnt;
|
|
off_t uio_offset;
|
|
size_t uio_resid;
|
|
enum uio_rw uio_rw;
|
|
struct vmspace *uio_vmspace;
|
|
};
|
|
.Ed
|
|
.Pp
|
|
A
|
|
.Va struct uio
|
|
typically describes data in motion.
|
|
Several of the fields described below reflect that expectation.
|
|
.Bl -tag -width "uio_vmspace "
|
|
.It Va uio_iov
|
|
Pointer to array of
|
|
.Tn I/O
|
|
vectors to be processed.
|
|
The
|
|
.Va struct iovec
|
|
is defined to be:
|
|
.Bd -literal -offset indent
|
|
struct iovec {
|
|
void *iov_base;
|
|
size_t iov_len;
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The members in the
|
|
.Va struct iovec
|
|
should only be initialized.
|
|
These are:
|
|
.Bl -tag -width "*iov_base " -offset indent
|
|
.It Va iov_base
|
|
The address for a range of memory to or from which data is transferred.
|
|
.It Va iov_len
|
|
The number of bytes of data to be transferred to
|
|
or from the range of memory starting at
|
|
.Va iov_base .
|
|
.El
|
|
.It Va uio_iovcnt
|
|
The number of
|
|
.Tn I/O
|
|
vectors in the
|
|
.Va uio_iov
|
|
array.
|
|
.It Va uio_offset
|
|
An offset into the corresponding object.
|
|
.It Va uio_resid
|
|
The amount of space described by the structure; notionally, the amount
|
|
of data remaining to be transferred.
|
|
.It Va uio_rw
|
|
A flag indicating whether data should be read into the space
|
|
(UIO_READ) or written from the space (UIO_WRITE).
|
|
.It Va uio_vmspace
|
|
A pointer to the address space which is being transferred to or from.
|
|
.El
|
|
.Pp
|
|
The value of
|
|
.Va uio->uio_rw
|
|
controls whether
|
|
.Fn uiomove
|
|
copies data from
|
|
.Fa buf
|
|
to
|
|
.Fa uio
|
|
or vice versa.
|
|
.Pp
|
|
The lesser of
|
|
.Fa n
|
|
or
|
|
.Va uio->uio_resid
|
|
bytes are copied.
|
|
.Pp
|
|
.Fn uiomove
|
|
changes fields of the structure pointed to by
|
|
.Fa uio ,
|
|
such that
|
|
.Va uio->uio_resid
|
|
is decremented by the amount of data moved,
|
|
.Va uio->uio_offset
|
|
is incremented by the same amount, and the array of iovecs is adjusted
|
|
to point that much farther into the region described.
|
|
This allows multiple calls to
|
|
.Fn uiomove
|
|
to easily be used to fill or drain the region of data.
|
|
.Sh RETURN VALUES
|
|
Upon successful completion,
|
|
.Fn uiomove
|
|
returns 0.
|
|
If a bad address is encountered,
|
|
.Er EFAULT
|
|
is returned.
|
|
.Sh SEE ALSO
|
|
.Xr copy 9 ,
|
|
.Xr ufetch 9 ,
|
|
.Xr ustore 9
|