1.\" $NetBSD: uiomove.9,v 1.3 1999/03/16 00:40:48 garbled Exp $ 2.\" 3.\" Copyright (c) 1996 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the NetBSD 17.\" Foundation, Inc. and its contributors. 18.\" 4. Neither the name of The NetBSD Foundation nor the names of its 19.\" contributors may be used to endorse or promote products derived 20.\" from this software without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 23.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 24.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 25.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 26.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 27.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 28.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 29.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 30.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 31.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32.\" POSSIBILITY OF SUCH DAMAGE. 33.\" 34.Dd February 12, 1999 35.Dt UIOMOVE 9 36.Os 37.Sh NAME 38.Nm uiomove 39.Nd move data described by a struct uio 40.Sh SYNOPSIS 41.Fd #include <sys/systm.h> 42.Ft int 43.Fn uiomove "void *buf" "int n" "struct uio *uio" 44.Sh DESCRIPTION 45 46The 47.Nm 48function copies up to 49.Fa n 50bytes between the kernel-space address pointed 51to by 52.Fa buf 53and the addresses described by 54.Fa uio , 55which may be in user-space or kernel-space. 56 57The 58.Fa uio 59argument is a pointer to a 60.Fa struct uio 61as defined by 62.Aq Pa sys/uio.h : 63.Bd -literal 64struct uio { 65 struct iovec *uio_iov; /* pointer to array of iovecs */ 66 int uio_iovcnt; /* number of iovecs in array */ 67 off_t uio_offset; /* offset into file this uio corresponds to */ 68 size_t uio_resid; /* residual i/o count */ 69 enum uio_seg uio_segflg; 70 enum uio_rw uio_rw; 71 struct proc *uio_procp;/* process if UIO_USERSPACE */ 72}; 73.Ed 74 75A 76.Fa struct uio 77typically describes data in motion. 78Several of the fields described below reflect that expectation. 79 80.Bl -tag -width uio_xxxxxx 81.It uio_iov 82Pointer to array of 83.Fa struct iovecs : 84.Bd -literal 85struct iovec { 86 void *iov_base; /* Base address. */ 87 size_t iov_len; /* Length. */ 88}; 89.Ed 90.It uio_iovcnt 91The number of iovecs in the array. 92.It uio_offset 93An offset into the corresponding object. 94.It uio_resid 95The amount of space described by the structure; notionally, the amount 96of data remaining to be transferred. 97.It uio_segflg 98A flag indicating whether the space described is in user-space 99(UIO_USERSPACE) or kernel-space (UIO_SYSSPACE). 100.It uio_rw 101A flag indicating whether date should be read into the space 102(UIO_READ) or written from the space (UIO_WRITE). 103.It uio_procp 104A pointer to the process whose data area is described by the 105structure, or NULL if the area is in kernel-space. 106.El 107 108The value of 109.Fa uio->uio_rw 110controls whether 111.Nm 112copies data from 113.Fa buf 114to 115.Fa uio 116or vice versa. 117 118The lesser of 119.Fa n 120or 121.Fa uio->resid 122bytes are copied. 123 124.Nm 125changes fields of the structure pointed to by 126.Fa uio , 127such that 128.Fa uio->uio_resid 129is decremented by the amount of data moved, 130.Fa uio->uio_offset 131is incremented by the same amount, and the array of iovecs is adjusted 132to point that much farther into the region described. 133This allows multiple calls to 134.Nm 135to easily be used to fill or drain the region of data. 136 137 138.Sh RETURN VALUES 139.Nm 140returns 0 on success or EFAULT if a bad address is encountered. 141 142.Sh SEE ALSO 143.Xr fetch 9 , 144.Xr store 9 , 145.Xr copy 9 146