101 lines
3.3 KiB
Groff
101 lines
3.3 KiB
Groff
.\" $NetBSD: fetch.9,v 1.10 1999/03/16 00:40:47 garbled Exp $
|
|
.\"
|
|
.\" Copyright (c) 1996 Jason R. Thorpe.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed by Kenneth Stailey.
|
|
.\"
|
|
.\" 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.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed for the NetBSD Project
|
|
.\" by Jason R. Thorpe.
|
|
.\" 4. The name of the author may not be used to endorse or promote products
|
|
.\" derived from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 January 7, 1996
|
|
.Dt FETCH 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm fetch ,
|
|
.Nm fubyte ,
|
|
.Nm fuibyte ,
|
|
.Nm fusword ,
|
|
.Nm fuswintr ,
|
|
.Nm fuword ,
|
|
.Nm fuiword
|
|
.Nd fetch data from user-space
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/types.h>
|
|
.Fd #include <sys/systm.h>
|
|
.Ft int
|
|
.Fn fubyte "void *base"
|
|
.Ft int
|
|
.Fn fusword "void *base"
|
|
.Ft int
|
|
.Fn fuswintr "void *base"
|
|
.Ft int
|
|
.Fn fuword "void *base"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
functions are designed to copy small amounts of data from user-space.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
routines provide the following functionality:
|
|
.Bl -tag -width "fuswintr()"
|
|
.It Fn fubyte
|
|
Fetches a byte of data from the user-space address
|
|
.Fa base .
|
|
.It Fn fusword
|
|
Fetches a short word of data from the user-space address
|
|
.Fa base .
|
|
.It Fn fuswintr
|
|
Fetches a short word of data from the user-space address
|
|
.Fa base .
|
|
This function is safe to call during an interrupt context.
|
|
.It Fn fuword
|
|
Fetches a word of data from the user-space address
|
|
.Fa base .
|
|
.El
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Nm
|
|
functions return the data fetched or -1 on failure.
|
|
Note that these functions all do "unsigned" access, and
|
|
therefore will never sign extend byte or short values.
|
|
This prevents ambiguity with the error return value
|
|
for all functions except
|
|
.Fn fuword .
|
|
.Sh BUGS
|
|
The function
|
|
.Fn fuword
|
|
has no way to unambiguously signal an error, because the
|
|
data it reads might legitimately be the same as the -1
|
|
used to indicate an error. The other functions do not
|
|
have this problem because the unsigned values returned
|
|
by those can never match the -1 error return value.
|
|
.Sh SEE ALSO
|
|
.Xr copy 9 ,
|
|
.Xr store 9
|