Re: RFC: sysctl additional functions/macros

Alfred Perlstein wrote:
Yes, but EINVAL please.

I wondered who would be the first to complain about that..

"Gee you Juniper people have no sense of humour" :-) :-)


Another idea would be a simplified SYSCTL_INT_PROC
that allowed one to define a function like so:

int
sysctl_handle_int_proc(void *handle, int *newval, int *max, int *min)
{


}

If this function returned '0' then 'newval' would be accepted.
Otherwise the function should return an error, most likely EINVAL.

The point being that a lot of these maximums may take a calculation
and we should make it as easy as possible to do this calculation
and provide the function for doing so.

One would also set the min/max values so that one could query
the acceptable bounds of a tunable, or even the bounds of of
the tuneable.

(Note: if *newval == NULL, we're just querying max/min, not
doing a set operation.)

(Note 2: "handle" is so you can have a common handler and
possibly switch() off of handle for multiple sysctl ints to
reduce the number of functions required.)

-Alfred

* Julian Elischer <julian@xxxxxxxxxxxx> [080103 17:57] wrote:
I would like to extend the current SYSCTL_INT() with SYSCTL_INT_CLAMPED() or similar, where you also supply a
maximum acceptable value. (and maybe a clue as to what to say if it is a bad value).

so many users of SYSCTL_INT don't check for bad values because it's so
much harder (you need to supply your own handler), and so many
simple handlers exist fo rthe people that DO check that it seems to
me that we should provide a pre-canned way to do this....

we are limited to using the existing structure,
but as we have no existing callers we can redefine
one element....

I would suggest:

I'd like to test for a minimum too but I think I can only squeeze one field out of the existing struct sysctl_oid.

SYSCTL_INT_CLAMPED(parent, nbr, name, access, ptr, max, descr)
^^^^

anyone think it's a bad idea?
After all the macros are evaluated, (etc.) it would call:
( off the top of my head )

int
sysctl_handle_int_max(SYSCTL_HANDLER_ARGS)
{
int error = 0;

error = SYSCTL_OUT(req, arg1, sizeof(int));

if (error || !req->newptr)
return (error);

if (*(int *)arg1 > (int)arg2)
error = EDOOFUS;
else
error = SYSCTL_IN(req, arg1, sizeof(int));
return (error);
}
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