fetch(9) - NetBSD Manual Pages

FETCH(9)                     NetBSD Kernel Manual                     FETCH(9)


NAME
fetch, fubyte, fuibyte, fusword, fuswintr, fuword, fuiword - fetch data from user-space
SYNOPSIS
#include <sys/types.h> #include <sys/systm.h> 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 con- text. 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 re- turn value for all functions except fuword().
SEE ALSO
copy(9), store(9)
BUGS
The function fuword() has no way to unambiguously signal an error, be- cause 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. NetBSD 1.6 January 7, 1996 1

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