[Samba] How do I lock a shared file?

Volker Lendecke Volker.Lendecke at SerNet.DE
Thu Sep 5 06:33:41 MDT 2013

On Thu, Sep 05, 2013 at 02:23:10PM +0200, steve wrote:
> It's a pity that we'll have to work around it. Surely Samba knows if a
> file is open or not doesn't it?  What's all this oplock stuff? It would

Samba certainly knows if a file is open. But it is by no way
safe that an application really opens a file that is being
edited exactly once. It is perfectly valid for an
application to load a file into memory, close it and then
let the user edit it. When the user presses a "save" button,
the file can be opened again, saved and closed immediately.
Perfectly valid, I'm sure there are many applications out
there that do exactly that. This will make it impossible for
Samba to protect applications against each other.

Did you 100% check that each and every of your applications
does open a file exactly once and never twice? I definitely
know that for example the pretty popular Microsoft Excel
application fails in this regard.

> I realise that it's not for everybody. Would that be hard to implement?

Feel free to submit a patch for this. Sorry for not doing it
myself, I highly doubt that this will work across all
clients, and I also highly doubt that it will help you in
even the majority of your cases.

With best regards,

Volker Lendecke

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