Date: Tue, 12 Jan 1999 17:49:34 +0100
From: Laszlo Molnar <laszlo DOT molnar AT eth DOT ericsson DOT se>
To: djgpp-workers AT delorie DOT com
Subject: Re: djgpp 2.02 + perl + glob
Message-ID: <19990112174934.W29345@duna54>
References: <19990112094755 DOT O29345 AT duna54> <Pine DOT SUN DOT 3 DOT 91 DOT 990112112109 DOT 15876Y-100000 AT is>
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In-Reply-To: <Pine.SUN.3.91.990112112109.15876Y-100000@is>; from Eli Zaretskii on Tue, Jan 12, 1999 at 11:24:57AM +0200
Reply-To: djgpp-workers AT delorie DOT com

On Tue, Jan 12, 1999 at 11:24:57AM +0200, Eli Zaretskii wrote:
> > The problem: when a new handle is
> > allocated, it is not opened, but dup()-ed in djgpp 2.02.
> Right.  This change was done to prevent fsext from failing when it 
> exhausts the max count of handles determined by the FILES= directive.  
> `dup' is not limited by FILES=, and so can go up to the maximum of 255 
> handles that DOS allows.
> > It would work
> > perfectly if the file pointer would be set to 0, ie an lseek(..,0,0)
> > should be added after dup() IMHO.
> Can you elaborate why is this needed?  Is this something specific to the 
> way Perl uses fsext, or do you think this is a general problem, and why?

Ok, here is how perl uses the fsext: when a globbing request arrives I
call glob(), copy all filenames to an array and allocate the fsext
handle. Next time a read request arrives on the handle, and I copy the
requested bytes to the user from my buffer. The file pointer on the
handle is updated of course. If a new glob() request arrives and I
allocate (ie. open) another handle, its file pointer won't be set to 0
because of dup. So when a reading request arrives on the second handle
I will possibly pass garbage to the user.

I think this is a general problem, because when a file handle is
allocated (opened) I would expect its file pointer set to 0. Or am I
missing something?

> Don't forget that lseek itself might be hooked by the fsext, btw.

Yes, this might be a problem. But not using it is a bigger one IMO.

Laszlo