Re: [Linux-decnet-user] Feature request

[Patrick C. <pa...@ty...>]

On Thu, May 20, 2004 at 04:17:43PM -0400, Stanley F. Quayle wrote:
> Let me explain what I'm doing now, and see if this is possible in 
> Linux DECnet.
> 
> I have a Linux box (RH 7.2) NFS exporting a chunk of disk to my VMS 
> systems.  The VMS systems do daily backups to the Linux box.  Also, I 
> have a whole chunk of data on the Linux box that the VMS systems 
> "see" as VMS files, characteristics and all.
> 
> How this works is that, when I create a file from the VMS system, two 
> files get created on the Linux system.  Suppose I create ABC.XYZ;27 
> on VMS.  On the Linux box, I get:
> 
>  abc.xyz;27          and
>  .$ADF$abc.xyz;27		(this is "hidden" because of the leading dot)
> 
> (There's also a "abc.xyz" hard-linked to the "abc.xyz;27" to support 
> version numbers, but let's not go there.)  By the way -- this is all 
> handled by the VMS TCP/IP stack.
> 
> Anyway, the .$ADF$ file is 90 bytes long, and holds the VMS 
> characteristics of the file.
> 
> When I access the file from VMS, it gets reported back as whatever 
> characteristics it had when I created it.  If I delete the .$ADF$ 
> file, it comes back as Stream-LF.
> 
> Not knowing anything about the underlying DECnet protocol, it would 
> seem that FAL on the receiving system gets the characteristics on 
> files being sent.  And on files being "pulled", it reports the 
> characteristics back.
> 
> How hard would it be to modify the FAL on Linux to do something like 
> this?

FAL already does this to a limited extent. if you add the -m switch to the
daemon (in /etc/dnetd.conf) it will create a .fal directory and put metadata
files in there. It can also, to a limited extent, understand the $ADF$ files 
that the VMS NFS client puts there if you also use -t.

A good combination of options for FAL is "-m -t -ae" which will use .fal files
where files are createdbut it, $ADF$ files when created by NFS, and use file
extension-based guessing for files with no other information.
-- 

patrick