Subject: Re: kqueue, NOTE_EOF
To: Jaromir Dolecek <>
From: Bill Studenmund <>
List: tech-kern
Date: 11/12/2003 09:27:50
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Wed, Nov 12, 2003 at 09:58:15AM +0100, Jaromir Dolecek wrote:
> marius aamodt eriksen wrote:
> > hi -=20
> >=20
> > in order to be able to preserve consistent semantics across poll,
> > select, and kqueue (EVFILT_READ), i propose the following change: on
> > EVFILT_READ, add an fflag NOTE_EOF which will return when the file
> > pointer *is* at the end of the file (effectively always returning on
> > EVFILT_READ, but setting the NOTE_EOF flag when it is at the end).
> >=20
> > specifically, this allows libevent[1] to behave consistently across
> > underlying polling infrastructures (this has become a practical
> > issue).
> I'm not sure I understand what is the exact issue.

I'm only responding to the notes also.

> Why would this be necessary or what does this exactly solve? AFAIK
> poll() doesn't set any flags in this case neither, so I don't
> see how this is inconsistent.

I think the difference is in the default behavior. When you're at EOF, I=20
know that poll() will give you a read-availability event, so you'll read=20
the EOF. Will kqueue?

> BTW, shouldn't the EOF flag be cleared when the file is extended?


Take care,


Content-Type: application/pgp-signature
Content-Disposition: inline

Version: GnuPG v1.2.3 (NetBSD)