137 lines
4.1 KiB
Groff
137 lines
4.1 KiB
Groff
.\" $NetBSD: uiomove.9,v 1.12 2007/03/07 22:40:24 rmind Exp $
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.\"
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.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
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.\" 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 NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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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 February 12, 1999
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.Dt UIOMOVE 9
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.Os
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.Sh NAME
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.Nm uiomove
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.Nd move data described by a struct uio
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.Sh SYNOPSIS
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.In sys/systm.h
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.Ft int
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.Fn uiomove "void *buf" "size_t n" "struct uio *uio"
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.Sh DESCRIPTION
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The
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.Nm
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function copies up to
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.Fa n
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bytes between the kernel-space address pointed
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to by
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.Fa buf
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and the addresses described by
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.Fa uio ,
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which may be in user-space or kernel-space.
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.Pp
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The
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.Fa uio
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argument is a pointer to a
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.Fa struct uio
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as defined by
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.Aq Pa sys/uio.h :
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.Bd -literal
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struct uio {
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struct iovec *uio_iov; /* pointer to array of iovecs */
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int uio_iovcnt; /* number of iovecs in array */
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off_t uio_offset; /* offset into file this uio corresponds to */
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size_t uio_resid; /* residual i/o count */
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enum uio_rw uio_rw;
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struct vmspace *uio_vmspace;
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};
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.Ed
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.Pp
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A
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.Fa struct uio
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typically describes data in motion.
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Several of the fields described below reflect that expectation.
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.Pp
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.Bl -tag -width uio_xxxxxx
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.It uio_iov
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Pointer to array of
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.Fa struct iovecs :
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.Bd -literal
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struct iovec {
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void *iov_base; /* Base address. */
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size_t iov_len; /* Length. */
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};
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.Ed
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.It uio_iovcnt
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The number of iovecs in the array.
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.It uio_offset
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An offset into the corresponding object.
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.It uio_resid
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The amount of space described by the structure; notionally, the amount
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of data remaining to be transferred.
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.It uio_rw
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A flag indicating whether data should be read into the space
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(UIO_READ) or written from the space (UIO_WRITE).
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.It uio_vmspace
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A pointer to the address space which is being transferred to or from.
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.El
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.Pp
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The value of
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.Fa uio-\*[Gt]uio_rw
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controls whether
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.Nm
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copies data from
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.Fa buf
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to
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.Fa uio
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or vice versa.
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.Pp
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The lesser of
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.Fa n
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or
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.Fa uio-\*[Gt]uio_resid
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bytes are copied.
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.Pp
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.Nm
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changes fields of the structure pointed to by
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.Fa uio ,
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such that
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.Fa uio-\*[Gt]uio_resid
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is decremented by the amount of data moved,
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.Fa uio-\*[Gt]uio_offset
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is incremented by the same amount, and the array of iovecs is adjusted
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to point that much farther into the region described.
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This allows multiple calls to
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.Nm
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to easily be used to fill or drain the region of data.
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.Sh RETURN VALUES
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.Nm
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returns 0 on success or EFAULT if a bad address is encountered.
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.Sh SEE ALSO
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.Xr copy 9 ,
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.Xr fetch 9 ,
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.Xr store 9
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