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| FETCH(9) | FreeBSD Kernel Developer's Manual | FETCH(9) |
NAME
fetch, fubyte,
fuword, fuword16,
fuword32, fuword64,
fueword, fueword32,
fueword64 —
SYNOPSIS
#include <sys/types.h>
#include <sys/systm.h>
int
fubyte(volatile
const void *base);
long
fuword(volatile
const void *base);
int
fuword16(volatile
const void *base);
int32_t
fuword32(volatile
const void *base);
int64_t
fuword64(volatile
const void *base);
int
fueword(volatile
const void *base, long
*val);
int
fueword32(volatile
const void *base, int32_t
*val);
int
fueword64(volatile
const void *base, int64_t
*val);
DESCRIPTION
Thefetch functions are designed to copy small amounts
of data from user-space of the current process. If the user address is
naturally aligned, then the operation will be performed atomically. Otherwise
it may fail or be performed non-atomically, depending on the platform.
The fetch routines provide the following
functionality:
fubyte()- Fetches a byte of data from the user-space address base. The byte read is zero-extended into the results variable.
fuword()- Fetches a word of data (long) from the user-space address base.
fuword16()- Fetches 16 bits of data from the user-space address base. The half-word read is zero-extended into the results variable.
fuword32()- Fetches 32 bits of data from the user-space address base.
fuword64()- Fetches 64 bits of data from the user-space address base.
fueword()- Fetches a word of data (long) from the user-space address base and stores the result in the variable pointed by val.
fueword32()- Fetches 32 bits of data from the user-space address base and stores the result in the variable pointed by val.
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 fuword(),
fuword32() and fuword64()
functions cannot distinguish between -1 read from userspace and function
failure.
RETURN VALUES
Thefubyte(), fuword(),
fuword16(), fuword32(), and
fuword64() functions return the data fetched or -1 on
failure. The fueword(),
fueword32() and fueword64()
functions return 0 on success and -1 on failure.
SEE ALSO
copy(9), store(9)| July 22, 2021 | FreeBSD 13.1-RELEASE |
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