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Date:      Sat, 27 Apr 1996 15:12:46 -0400 (EDT)
From:      Peter Dufault <dufault@hda.com>
To:        bde@zeta.org.au (Bruce Evans)
Cc:        freebsd-doc@FreeBSD.org, jmacd@CS.Berkeley.EDU, freebsd-hackers@FreeBSD.org
Subject:   Re: O_SYNC
Message-ID:  <199604271912.PAA09603@hda.com>
In-Reply-To: <199604270258.MAA07041@godzilla.zeta.org.au> from "Bruce Evans" at Apr 27, 96 12:58:55 pm

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> 
> >Isn't O_SYNC the POSIX way to do things?  Why does FreeBSD have
> >O_FSYNC, and why isn't it documented?
> 
> POSIX.1 doesn't specify any way to sync files.  Perhaps FreeBSD
> has O_FSYNC as a compatibility hack, and it isn't documented because
> it doesn't do anything.

The new copy of POSIX.1 (P1003.1b-1993) adds O_DSYNC, O_RSYNC
and O_SYNC in the open call.  O_DSYNC versus O_SYNC permits data-only
integrity versus full file info integrity (access stamps, etc).
I haven't spent the time to puzzle out exactly what O_RSYNC means
- that once you read it it better also be on the disk?

There is a feature test macro "_POSIX_SYNCHRONIZED_IO" that has to
be defined for these to be present.

Anyone working off a new spec better keep an eye out for the change bars-
I didn't realize this was new until this mail.

-- 
Temporarily via "hdalog@zipnet.net"...

Peter Dufault               Real-Time Machine Control and Simulation
HD Associates, Inc.         Voice: 508 433 6936
dufault@hda.com             Fax:   508 433 5267



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