Date: Wed, 26 Aug 2009 12:09:47 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: "Mikhail T." <mi+thun@aldan.algebra.com> Cc: freebsd-fs@freebsd.org Subject: Re: semantics of fcntl() with l_len being 0 Message-ID: <20090826090947.GS9623@deviant.kiev.zoral.com.ua> In-Reply-To: <4A94B829.3090202@aldan.algebra.com> References: <4A94B829.3090202@aldan.algebra.com>
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On Wed, Aug 26, 2009 at 12:20:57AM -0400, Mikhail T. wrote:
> Hello!
>=20
> I'm curious, whether a file, that's locked (via fcntl) with l_start and
> l_len being 0 is supposed to be appendable...
>=20
> I would think so, but I notice, that when spamprobe (see mail/spamprobe)
> chews on my spam mailbox, I can not append a new piece of spam to the
> file -- my imap-server is waiting for spamprobe to finish.
>=20
> The fcntl(2) says: ``len =3D 0 means until end of file''. Is that ``until
> the end of file AT THE TIME OF LOCKING'' or simply ``no other lock until
> we are done''? Thanks. Yours,
SUSv3 is definitive on the subject:
A lock shall be set to extend to the largest possible value of the file
offset for that file by setting l_len to 0. If such a lock also has
l_start set to 0 and l_whence is set to SEEK_SET, the whole file shall
be locked.
=46rom sys/kern/kern_lockf.c, line 464:
} else if (fl->l_len =3D=3D 0) {
end =3D OFF_MAX;
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