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Mail Archives: djgpp-workers/1999/10/14/18:09:57

Sender: richdawe AT bigfoot DOT com
Message-ID: <3806512C.659F1CC0@tudor21.net>
Date: Thu, 14 Oct 1999 22:54:52 +0100
From: Richard Dawe <richdawe AT bigfoot DOT com>
X-Mailer: Mozilla 4.51 [en] (X11; I; Linux 2.2.10 i586)
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To: djgpp-workers AT Delorie DOT com
Subject: Re: /dev/zero support
References: <Pine DOT SUN DOT 3 DOT 91 DOT 991014103916 DOT 26124E-100000 AT is>
Reply-To: djgpp-workers AT delorie DOT com

Hello.

Eli Zaretskii wrote:
> I suggest to use the same method used by termios: introduce a special
> hook that I/O functions know about, and which gets called after user's
> FSEXTs, but before the DOS function calls.  It is possible that you
> can use the same hook already used by termios, just extend it with
> some flags and add the calls that implement /dev/zero support.
> 
> Another, possibly simpler, alternative would be to make /dev/zero be
> mapped to the null device, the same way /dev/null is handled, but mark
> the handle in some special way, so that _read will return a block of
> zeroes instead of actually reading.

You've convinced me a hook is a better solution. I think making a generic
solution would be a good idea, because then it would make implementing
other /dev/* devices simpler. I think this would be a neater solution than
the special handle method, but I haven't looked at the code yet, so this
is just speculation.

'Tis a shame I can't use a File System Extension, because that would be
very simple. Ah well.

> > A grep of the DJGPP libc sources didn't yield anything that looked
> > like /dev/null support.
> 
> Somehow, you didn't grep it all, or maybe you looked for a literal
> "/dev/null" (you won't find it).  The support for /dev/* is in
> src/libc/dos/io/putpath.c.

I grepped for /dev/null hopefully, but also just null. I guess it helps if
you know what to look for ;) I'll examine this code.

Thanks - that was exactly the guidance I was hoping for!

-- 
Richard Dawe
richdawe AT bigfoot DOT com ICQ 47595498 http://www.bigfoot.com/~richdawe/

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