Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!csource!david
From: david@csource.OZ.AU (david nugent)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Retrieving the value of FILES=???
Keywords: Global File Handle Table
Message-ID: <529@csource.OZ.AU>
Date: 17 Jun 90 03:30:05 GMT
References: <605@digigw.digital.co.jp> <4057@jato.Jpl.Nasa.Gov>
Organization: Unique Computing Pty Ltd, Melb, Aust.
Lines: 54

In <4057@jato.Jpl.Nasa.Gov> kaleb@mars.jpl.nasa.gov (Kaleb Keithley) writes:

>How about: (in psuedo-code)

>#ifdef DOS
>    fopen ("/CONFIG.SYS", "r");
>    fscanf (..., "FILES=", ...);
>    fscanf (...,  value, ...);
>    fclose (...);
>#else
>    other method appropriate for architecture
>#end

>Since all DOS machines have to have CONFIG.SYS in the root directory, it
>would work for any DOS box.  If the fopen fails, then assume the default.


Several pitfalls;

	How do you determine what drive the system booted from? (and
	don't say looking at COMSPEC - even my own system boots DOS
	from a floppy and I have "SHELL=C:\COMMAND.COM ..." on it,
	which makes that assumption completely invalid),

	How can you guarantee that CONFIG.SYS hasn't been edited since
	boot,

	Some application may have adjusted the number of allowed
	handles using DOS Fn 67H,

	What if there's no FILES= statement (use the MS-DOS default -
	but since DOS Fn 67H exists, that's also a problem),

	How do you handle workstations on a network using an auto-
	boot PROM where CONFIG.SYS is no longer available since the
	system boots from what is essentially a temporary memory image,

	What about a dual boot OS/2 system which might use something
	like CONFIG.DOS instead of CONFIG.SYS,

	How do you handle "DOS-like" environments such as PC-MOS/386
	where a FILES= statement is invalid, yet there IS no practical
	limit to the number of handles; certainly the DOS default does
	NOT apply

Reading CONFIG.SYS is a kludge, at best.  If you need this information,
it's for a reason - and relying on extremely unreliable sources can get
you into trouble very quickly.

david

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