Re: Extattr portability?

From: Robert Watson <rwatson_at_FreeBSD.org>
Date: Sun, 11 Jan 2009 18:52:17 +0000 (GMT)
On Sat, 10 Jan 2009, Tim Kientzle wrote:

> Dylan Cochran wrote:
>> 
>> Another is BeOS/Haiku, which used attributes heavily. I have been waiting 
>> for this work for a while. What I don't really mind is whether it is 
>> portable, what I really care about is full retention of the user namespace. 
>> ...
>> 
>> That's my 2 cents on the matter, I use extended attributes now for storing 
>> cached mime-type, and sha256/md5 for checksum purposes.
>
> Wonderful!  Care to help test?
>
> There's still a lot of open questions about the system namespace I'll have 
> to figure out.  Over on the GNU tar mailing list, the Linux filesystem folks 
> have been agitating for GNU tar to support system extattrs that carry 
> filesystem layout hints.  The portability issues with this make my head 
> hurt.

One of the things I've been considering for FreeBSD is pulling in the xattr 
API used on Mac OS X and Linux -- our API was modeled on the POSIX.1e ACL API 
in a manner similar to IRIX, which it was intended to support, and while it 
looked like Linux might adopt the model we used, they eventually didn't. 
There are some semantic differences, most importantly that the "namespace" 
model is quite different.  I have a TODO list item somewhere to ask about 
getting the source files from Apple relicensed under a BSD license so we can 
share code there, but haven't quite gotten to that yet.

Robert N M Watson
Computer Laboratory
University of Cambridge
Received on Sun Jan 11 2009 - 17:52:17 UTC

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