fueword (9)

Leading comments

	$NetBSD: fetch.9,v 1.2 1996/01/09 21:59:24 perry 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 fo...

(The comments found at the beginning of the groff file "man9/fueword.9freebsd".)

NAME

fetch fubyte fuswintr fuword fuword16 fuword32 fuword64 fueword fueword32 fueword64 - fetch data from user-space

SYNOPSIS

In sys/types.h In sys/systm.h Ft int Fn fubyte volatile const void *base Ft long Fn fuword volatile const void *base Ft int Fn fuword16 volatile const void *base Ft int32_t Fn fuword32 volatile const void *base Ft int64_t Fn fuword64 volatile const void *base Ft long Fn fueword volatile const void *base long *val Ft int32_t Fn fueword32 volatile const void *base int32_t *val Ft int64_t Fn fueword64 volatile const void *base int64_t *val In sys/resourcevar.h Ft int Fn fuswintr void *base

DESCRIPTION

The functions are designed to copy small amounts of data from user-space of the current process. If read is successful, it is performed atomically. The data read must be naturally aligned.

The routines provide the following functionality:

Fn fubyte

Fetches a byte of data from the user-space address base The byte read is zero-extended into the results variable.

Fn fuword

Fetches a word of data (long) from the user-space address base

Fn fuword16

Fetches 16 bits of data from the user-space address base The half-word read is zero-extended into the results variable.

Fn fuword32

Fetches 32 bits of data from the user-space address base

Fn fuword64

Fetches 64 bits of data from the user-space address base

Fn fuswintr

Fetches a short word of data from the user-space address base This function is safe to call during an interrupt context.

Fn fueword

Fetches a word of data (long) from the user-space address base and stores the result in the variable pointed by val

Fn fueword32

Fetches 32 bits of data from the user-space address base and stores the result in the variable pointed by val

Fn fueword64

Fetches 64 bits of data from the user-space address base and stores the result in the variable pointed by val

The callers of Fn fuword , Fn fuword32 and Fn fuword64 functions cannot distinguish between -1 read from userspace and function failure.

RETURN VALUES

The Fn fubyte , Fn fuword , Fn fuword16 , Fn fuword32 , Fn fuword64 , and Fn fuswintr functions return the data fetched or -1 on failure. The Fn fueword , Fn fueword32 and Fn fueword64 functions return 0 on success and -1 on failure.

SEE ALSO

copy(9), store(9)