From: Eric Schwartz <emschwar@...>
Date: 2004-08-25T05:20:40+09:00
Subject: Re: Find the number of open files

Charles Mills <cmills@freeshell.org> writes:
> I am unittesting a C extension.  The extension opens files using 
> open().  I want to make sure that the extension closes all the files it 
> opens (when errors occur or whatever).

Call me crazy, but what's wrong with adding each file descriptor you
open into a list, and then traversing that list at error time (or
whatever) to make sure they're all closed?

> So I figured getting a count of open file descriptors before the 
> extension code is called and after it is finished would enable me to do 
> this.

I'm not sure what that would buy you.  If your extension code can take
a block, you're completely screwed-- that block may open new
filehandles, or close old ones, and your count-based approach would be
totally out into the weeds.  Even if it doesn't, signal handlers and
other asynchronous code may open or close them without your explicit
knowledge.  

Besides, knowing how many descriptors are open is a far cry from
knowing *which* descriptors are open, which is necessary to close()
them.

-=Eric
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