fcntl cooperation with server side processes

Chris Green cmg at dok.org
Thu Jul 22 00:37:18 GMT 2004

David Collier-Brown wrote:

>   Hmmn, as a command-like parameter, perhaps, called
> something like --wait-for-exclusive_open ??
>   Chris, this might be a suitable approach... opinions?

I really think think the smbstatus + grep is the best cross platform 
solution for me right now.  My main concern is making sure the entire 
file is there so as long as I can see the file's status and know it's in 
the process of being modified so that I can process the file and delete 
it.    If I needed fancier semantics than that, I'd have no problem 
writing a custom windows program to ensure the lock gets there.

If  I understand correctly, the oplocks that say DENY_ALL will cause an 
smbclient get to fail or block ( not sure on semantics and my notes are 
at work ) so if I were to smbclient from myself, things would just 
work.   The only problem would be attempting to connect to a remote 
system and ensure that files are being copied.   In that case, being 
able to specify the Deny Mode would be useful.

Under Linux 2.4+, I think the problem is solved for me by attempting to 
do a F_SETLEASE for a write lease.
As long as any other process has the file open,  the kernel won't pass 
out a write lease.

The only problem with this method is that Linux returns an EACCESS 
unless the uid of the file owner == uid of the file process.
I've mailed the last 2 people that did changes to Linux to add the 
leases to see why that is.   My feeling is that write leases should be 
granted to anyone that has write permission to the file. 

Does anyone know what the access restrictions  are under IRIX?

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