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FETCH(9) BSD Kernel Developer’s Manual FETCH(9)

NAME

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

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);

long

fueword(volatile const void *base, long *val);

int32_t

fueword32(volatile const void *base, int32_t *val);

int64_t

fueword64(volatile const void *base, int64_t *val);

#include <sys/resourcevar.h>

DESCRIPTION

The fetch 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 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

The fubyte(), 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)

BSD April 17, 2018 BSD

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