[Samba] Support for multiple file streams?

[Jeremy Allison]

On Thu, Jun 28, 2007 at 05:54:28AM +0200, Guenter Kukkukk wrote:
> 
> there is currently _no_ way to (exactly) represent MS ntfs alternate
> data streams on *nix file systems!
> 
> The approach to store them on the *nix side into the xattr file space
> - or into a separate DB - (like samba4 is doing) is a first go, but
> can never meet the "the nearly unlimited" size of ads on MS systems.
> 
> Ext2/ext3 has a limited xattr size of about 4KB (!), other file systems
> (reiserfs, xfs, jfs, ...) allow about (restricted multiples) of 64KB.
> 
> Anyway - _big_ "alternate data streams" on current *nix systems is
> a "no go"!
> 
> The good news. MS alternate data streams haven't been used
> heavily in the past - and the currently used sizes could be 
> represented by using the very simple *nix xattr space.
> 
> Samba4 is going that way, and samba3 atm has no chance to do
> it a different way...

I really dislike mapping streams into EA's - I think in
the long run this will be a disaster. I'd rather use
a .streams: directory and store streams as directories
within it. It sucks for plain POSIX but will give correct
(seekable + large size) semantics for Windows clients.

We also need to be able to map onto systems that support
openat().

Jeremy.