KFILTER_REGISTER(9) | Kernel Developer's Manual | KFILTER_REGISTER(9) |
kfilter_register
,
kfilter_unregister
—
#include <sys/event.h>
int
kfilter_register
(const
char *name, struct
filterops *filtops, int
*retfilter);
int
kfilter_unregister
(const
char *name);
kfilter_register
() function adds a new kernel event
filter (kfilter) to the system, for use by callers of
kqueue(2) and
kevent(2).
name is the name of the new filter (which must not
already exist), and filtops is a pointer to a
filterops structure which describes the filter
operations. Both name and filtops
will be copied to an internal data structure, and a new filter number will be
allocated. If retfilter is not
NULL
, then the new filter number will be returned in
the address pointed at by retfilter.
The kfilter_unregister
() function removes
a kfilter named name that was previously registered
with kfilter_register
(). If a filter with the same
name is later reregistered with
kfilter_register
(), it will get a different filter
number (i.e., filter numbers are not recycled). It is not possible to
unregister the system filters (i.e., those that start with
“EVFILT_” and are documented in
kqueue(2)).
The filterops structure is defined as follows:
struct filterops { int f_isfd; /* true if ident == filedescriptor */ int (*f_attach)(struct knote *kn); /* called when knote is ADDed */ void (*f_detach)(struct knote *kn); /* called when knote is DELETEd */ int (*f_event)(struct knote *kn, long hint); /* called when event is triggered */ };
If the filter operation is for a file descriptor, f_isfd should be non-zero, otherwise it should be zero. This controls where the kqueue(2) system stores the knotes for an object.
kfilter_register
() returns 0 on success,
EINVAL
if there's an invalid argument, or
EEXIST
if the filter already exists,
kfilter_unregister
() returns 0 on success,
EINVAL
if there's an invalid argument, or
ENOENT
if the filter doesn't exist.
kfilter_register
() and
kfilter_unregister
() functions first appeared in
NetBSD 2.0.
kfilter_register
() and
kfilter_unregister
() functions were implemented by
Luke Mewburn ⟨lukem@NetBSD.org⟩.
October 23, 2002 | NetBSD 9.2 |