NAME
fetch,
fubyte,
fuibyte,
fusword,
fuswintr,
fuword,
fuiword
- fetch data from user-space
SYNOPSIS
int
fubyte(
const void *base
)
int
fusword(
const void *base
)
int
fuswintr(
const void *base
)
long
fuword(
const void *base
)
DESCRIPTION
The
fetch
functions are designed to copy small amounts of data from user-space.
The
fetch
routines provide the following functionality:
- fubyte(
) -
Fetches a byte of data from the user-space address
base
.
- fusword(
) -
Fetches a short word of data from the user-space address
base
.
- fuswintr(
) -
Fetches a short word of data from the user-space address
base
.
This function is safe to call during an interrupt context.
- fuword(
) -
Fetches a word of data from the user-space address
base
.
RETURN VALUES
The
fetch
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
fuword(
).
SEE ALSO
copy(9),
store(9)
BUGS
The function
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.