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From: Andrew DeFaria <Andrew AT DeFaria DOT com>
Subject:  Re: Updated cygwin dlls cause unnecessary reboot on NT
Date:  Wed, 27 Dec 2006 20:17:03 -0600
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Eric Blake wrote:
> Actually, you are. The ONLY way to make renaming in-use .dlls work is 
> to make  fork() aware of the rename. The way fork() works is that it 
> must reload the same .dll as the parent process had loaded, and it 
> currently does this BY NAME. In other words, changing the name of an 
> in-use dll will break the child process, even if you then install 
> another dll at that location, because the new
> dll will have a different layout in memory, and will not reload 
> cleanly. For your scheme to work, you must teach fork() how to track 
> these renames, and load the original .dll by its new name, and not the 
> upgraded dll that now lives at the original name.
This part peaks my curiosity. Now I'm not a kernel guy however as you 
state fork currently knows which dlls to load for the child by name. 
While that makes sense on the outside what if it knew which dlls to load 
by number - by open file descriptor number that is? I mean wouldn't that 
be a clean way to change fork() to allow it to load the proper, in this 
case, old dlls?

Another question, how is this not a problem for Unix's fork()? Does 
Unix's fork also do this by name? Or does it use another mechanism?

(I'm not saying that Cygwin's fork == Unix's fork - indeed perhaps there 
are deep technical reasons why using a file descriptor approach is 
infeasible in Cygwin under Windows).

-- 

Andrew DeFaria <http://defaria.com>
A friend of mine is into Voodoo Acupuncture. You don't have to go. 
You'll just be walking down the street, and...........ooooohhhhhh, 
that's much better...


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