Sender: vheyndri AT rug DOT ac DOT be
Message-Id: <350659E5.1930@rug.ac.be>
Date: Wed, 11 Mar 1998 10:31:17 +0100
From: Vik Heyndrickx <Vik DOT Heyndrickx AT rug DOT ac DOT be>
Mime-Version: 1.0
To: Bill Currie <bill AT taniwha DOT tssc DOT co DOT nz>
Cc: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>, djgpp-workers AT delorie DOT com,
        Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Subject: Re: Temporary files considered unsafe
References: <Pine DOT SUN DOT 3 DOT 91 DOT 980310130222 DOT 4314B-100000 AT is> <350655E0 DOT A0EFE270 AT taniwha DOT tssc DOT co DOT nz>
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Bill Currie wrote:
> 
> Eli Zaretskii wrote:
> >
> > On Tue, 10 Mar 1998, Vik Heyndrickx wrote:
> >
> > > I've thought about STR-ing in the djgpp start-up code
> >                      ^^^^^^^
> > What's that?
> 
> Store Task Register.  However, I'm not certain windows uses task
> segments. 

I never thought so far, but you may be right, at least for W95's
predecessors.
Meaning that the TSS-selector is not a good candidate for a unique pid.
So let us forget about that.

> AFAICT from the Win3.0 VxD docs, the VMM (the real OS behind
> windows, also the DPMI provider) uses the ring 0 stack to hold task
> info, though I could easily be wrong.

That indeed makes sense for versions up Win3.1 that don't necessarily
run 'Enhanced' mode.
 
> My 386/486 programmers guide impiles that STR is
> allowed in ring 3 (only LTR isn't).

Mine doesn't. Although it isn't really a securite risk to allow that STR
instruction to run at CPL=3, so I could believe that.

> why not combine the dos psp and the windows vmid (?, can't remember the
> correct name, RBIL isn't handy at the moment :(, but I remember seeing a
> 2f16xx call to grab it).  Sure, you wind up with a 32 bit number, but
> that can be expressed in 6 chars (uuencode or related) with the rest (5
> if the extension is used) used for time/counter/whatever.

Problem is that the less bits are in the PID the easier it is to squeeze
them in a filename (the original reason for the quest for a good PID).
When there are 32 bits it may get impossible to combine them with a
'large enough' counter and the current time yielding an eight-character
filename.

-- 
 \ Vik /-_-_-_-_-_-_/   
  \___/ Heyndrickx /          
   \ /-_-_-_-_-_-_/