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Date: Tue, 01 Sep 2009 19:10:20 -0600
From: Eric Blake <ebb9 AT byu DOT net>
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To: cygwin AT cygwin DOT com
Subject: Re: struct dirent.d_reclen
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According to Christopher Faylor on 9/1/2009 5:37 PM:
> Maybe you mean d_namlen?

Yes; serves me right for confusing readdir(2) and readdir(3) man pages.

> It is not a given that adding d_reclen would speed anything up since it
> cause every single program that uses dirent to effectively perform a
> strlen on every record returned by readdir whether it needed that field
> or not.

Not so.  For example, fhandler_disk_file::readdir_helper is already doing
a sys_wcstombs to populate the d_name buffer, and that returns the length
as a side effect.  In other words, the cost of providing the length to the
client is an O(1) single assignment of an already-existing value per entry
(and when you consider that we are already assigning __d_unused1 to 0,
that means no net increase in cost to clients that don't care about the
length); whereas the current situation requires clients that care about
the length to use O(n) strlen() and duplicate something that was
previously calculated by cygwin1.dll.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9 AT byu DOT net
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