Date: Tue, 18 Dec 2018 15:08:51 -0500 From: Austin Shafer <amshafer64@gmail.com> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: ENOMEM when calling sysctl_handle_int from custom handler Message-ID: <m236quiomk.fsf@triplebuff.com> In-Reply-To: <CAFMmRNwyd6meO2LOfHLk8pg3y9x=RaE7hukw8cJAa0s%2BvgZTxg@mail.gmail.com> References: <861s6fpyua.fsf@triplebuff.com> <CAFMmRNwyd6meO2LOfHLk8pg3y9x=RaE7hukw8cJAa0s%2BvgZTxg@mail.gmail.com>
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Ryan Stone <rysto32@gmail.com> writes:
> You should not pass arg1 and arg2 to sysctl_handle_int(). You instead
> need to pass a pointer to a local value containing the value you want
> to return to the sysctl caller. After sysctl_handle_int returns, if
> it returned 0 and req->newptr is non-NULL, then the integer value will
> contain the new value that was passed to you from userland. You want
> something that looks like this:
>
> int
> my_sysctl_handler(SYSCTL_HANDLER_ARGS)
> {
> int val, error;
>
> val = 5; /* Or whatever value you want to return from userland. */
>
> error = sysctl_handle_int(oidp, &val, 0, req);
> if (error != 0 || req->newptr == NULL)
> return (error);
>
> /* val contains the value set by the caller, so do something
> interesting with it here. */
>
> return (0);
> }
Hmm yup this seems to be problem. I had originally tried to just pass
the handler args directly through to sysctl_handle_int to make sure I
was creating the nodes correctly, since I knew sysctl_handle_int
worked.
Thanks again for all the help on these beginner questions!
Austin Shafer
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