File locking ... need info

[Mike Robinson]

[Please reply e-mail; I don't yet subscribe.]

I am interested in support for file-locking and locking of specified regions 
of a file, in order to support databases such as MS-Access and Paradox.

But as I ponder the various likely-looking segments of the source-code, I 
really do not know where to begin ... nor what has been done in this area 
before.

It is clear that an implementation of locking must work on SMB-shares and that 
it should "actually lock things" in that other Windows users should see the 
locks as they are placed and removed.  It's also clear that implementing 
timeouts on these locks could be "problematic," since the Unix impl. of file 
locking is not quite the same as Windows expects.

Pointers?  Comments?  War-stories?  Advice?  "Someone already did that"s?