1.\" $NetBSD: fetch.9,v 1.2 1996/01/09 21:59:24 perry Exp $ 2.\" 3.\" Copyright (c) 1996 Jason R. Thorpe. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed by Kenneth Stailey. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed for the NetBSD Project 19.\" by Jason R. Thorpe. 20.\" 4. The name of the author may not be used to endorse or promote products 21.\" derived from this software without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 28.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 30.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" $FreeBSD$ 36.\" 37.Dd January 23, 2020 38.Dt FETCH 9 39.Os 40.Sh NAME 41.Nm fetch , 42.Nm fubyte , 43.Nm fuword , 44.Nm fuword16 , 45.Nm fuword32 , 46.Nm fuword64 , 47.Nm fueword , 48.Nm fueword32 , 49.Nm fueword64 50.Nd fetch data from user-space 51.Sh SYNOPSIS 52.In sys/types.h 53.In sys/systm.h 54.Ft int 55.Fn fubyte "volatile const void *base" 56.Ft long 57.Fn fuword "volatile const void *base" 58.Ft int 59.Fn fuword16 "volatile const void *base" 60.Ft int32_t 61.Fn fuword32 "volatile const void *base" 62.Ft int64_t 63.Fn fuword64 "volatile const void *base" 64.Ft int 65.Fn fueword "volatile const void *base" "long *val" 66.Ft int 67.Fn fueword32 "volatile const void *base" "int32_t *val" 68.Ft int 69.Fn fueword64 "volatile const void *base" "int64_t *val" 70.In sys/resourcevar.h 71.Sh DESCRIPTION 72The 73.Nm 74functions are designed to copy small amounts of data from user-space 75of the current process. 76If read is successful, it is performed atomically. 77The data read must be naturally aligned. 78.Pp 79The 80.Nm 81routines provide the following functionality: 82.Bl -tag -width "fueword32()" 83.It Fn fubyte 84Fetches a byte of data from the user-space address 85.Pa base . 86The byte read is zero-extended into the results variable. 87.It Fn fuword 88Fetches a word of data (long) from the user-space address 89.Pa base . 90.It Fn fuword16 91Fetches 16 bits of data from the user-space address 92.Pa base . 93The half-word read is zero-extended into the results variable. 94.It Fn fuword32 95Fetches 32 bits of data from the user-space address 96.Pa base . 97.It Fn fuword64 98Fetches 64 bits of data from the user-space address 99.Pa base . 100.It Fn fueword 101Fetches a word of data (long) from the user-space address 102.Pa base 103and stores the result in the variable pointed by 104.Pa val . 105.It Fn fueword32 106Fetches 32 bits of data from the user-space address 107.Pa base 108and stores the result in the variable pointed by 109.Pa val . 110.It Fn fueword64 111Fetches 64 bits of data from the user-space address 112.Pa base 113and stores the result in the variable pointed by 114.Pa val . 115.El 116.Pp 117The callers of 118.Fn fuword , 119.Fn fuword32 120and 121.Fn fuword64 122functions cannot distinguish between -1 read from 123userspace and function failure. 124.Sh RETURN VALUES 125The 126.Fn fubyte , 127.Fn fuword , 128.Fn fuword16 , 129.Fn fuword32 , 130and 131.Fn fuword64 132functions return the data fetched or -1 on failure. 133The 134.Fn fueword , 135.Fn fueword32 136and 137.Fn fueword64 138functions return 0 on success and -1 on failure. 139.Sh SEE ALSO 140.Xr copy 9 , 141.Xr store 9 142