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From: ranjit@eniac.seas.upenn.edu (Ranjit Bhatnagar)
Newsgroups: comp.sys.amiga.tech
Subject: Question about EXAMINE/EXNEXT
Message-ID: <8374@netnews.upenn.edu>
Date: 25 Feb 89 11:26:19 GMT
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Reply-To: ranjit@eniac.seas.upenn.edu.UUCP (Ranjit Bhatnagar)
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Organization: University of Pennsylvania
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What is the appropriate behavior for Examine/ExNext if the contents
of a directory change between one request and the next?  Should it
always report the most up-to-date information possible, even though
this may lead to inconsistent lists, or should it buffer the entire
directory at the time Examine is called, even though this may lead
to out-of-date information, and the buffer may be stuck forever if
the Examining program is aborted before it finishes?  

I have a feeling that no existing filesystem buffers the directory
list - but how do current filesystems handle this problem, then?
What if the directory entry last examined is deleted before ExNext
is invoked on it?  What if the next entry (the one the hypothetical
'next' pointer in the previous entry) is deleted?  What if EVERYTHING
is deleted?  

The only solution I can think of is to search the entire directory
every time its datestamp changes, and skip all those files which we've
already seen.  I suppose that it's possible to do an ExNext on a
directory entry that not only doesn't exist, but never did, because
the filesystem must assume that it did exist at some time.  

	- ranjit




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