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From:	"Rod Pemberton" <buzzoff AT nonamewhichexists DOT cmm>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: file close being called
Date:	Sun, 19 Oct 2014 16:51:18 -0400
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On Sun, 19 Oct 2014 13:07:14 -0400, Louis Santillan <lpsantil AT gmail DOT com>  
wrote:
> On Sat, Oct 18, 2014 at 6:25 PM, Rod Pemberton
> <buzzoff AT nonamewhichexists DOT cmm> wrote:

[fixed Usenet bottom posting]

>>
>> I'm seeing Int 21h, AH=3Eh (close file) being
>> called in protected mode (PM) or perhaps it's
>> being reflected to PM by the DPMI host.
>>
>> I've searched the sources for DJGPP and CWSDPMI
>> and I can find no indication that this interrupt
>> is called by DJGPP in PM or being reflected by
>> CWSDPMI to PM.
>>
>> Does anyone know why or where this is happening?
>>
>
> I think you're gonna need to tell us a whole lot more
> about your situation here.  DOS version, DOS drivers,
> TSRs, your source (smallest example thar exhibits the
> same issue) that is being run when you see this.
>

Ok.  I'm not sure why.  The issue was stated clearly.
And, I'd expect that DJ or Eli or Charles should know
about this ...

> DOS version,

MS-DOS v7.10 (Windows 98/SE)

This is 16-bit RM code.  So, it can only be the
cause if CWSDPMI is reflecting Int 21h, AH=3Eh
to PM.

> DOS drivers,

Japheth's HIMEMX

This is 16-bit RM code.  So, it can only be the
cause if CWSDPMI is reflecting Int 21h, AH=3Eh
to PM.

> TSRs,

Franck Umberto's XMSDSK

This is 16-bit RM code.  So, it can only be the
cause if CWSDPMI is reflecting Int 21h, AH=3Eh
to PM.

Those three things are all I load, normally.
I doubt that removing XMSDSK or chaning HIMEMX
back to HIMEM will change anything, but I'll check.

I conditionally load Henrik Haftmann's DOSLFN
or Nagy Daniel's CuteMouse when needed.  I'll use
P. Frosts DDL or David Woodhouse's DEVLOAD to
conditionally load other drivers.  In this case,
nothging but the three items above are loaded.

> your source (smallest example thar exhibits the
> same issue) that is being run when you see this.

As stated previously, the issue is not with my code.

It doesn't open or close any files or do anything
really.  It simply setups up
_go32_dpmi_chain_protected_mode_interrupt_vector()
for Int 21h, calls system(), and monitors what AH
is called for Int 21h in PM.  That's it.  When DJGPP
apps are executed they triggering Int 21h, AH=3Eh.
So, I know it's related to DJGPP apps and isn't
related to my code.

Int 21h, AH=3Eh and Int 21, AH=4Ch are being called.
4Ch is the DPMI exit in PM and DOS exit in RM.
All Int 21h calls, except AH=4Ch, should be redirected
to RM via a call to Int 31h and the DPMI host, CWSDPMI.
DJGPP is setup this way by design since there are no
callable interrupts in PM.  AIUI, only IRQ's, Int 21h
AH=4C, Int 1Ch, Int 23h, Int 24h, and Int 31h should
be normally seen in PM with DPMI hosts.

I'm just trying to find out why and where this one
interrupt is being called in PM, apparenlty by DJGPP
applications, when there are no interrupt routines
setup for PM.  E.g., is CWSDPMI monitoring it for
some reason?  Is DJGPP CRT calling it?  Etc.  Where?

I need to know if I can block this, unchain this,
or prohibit it in PM, and what it'll mess up if
anything.

So, DJGPP's CRT, or perhaps something int DJGPP's
library for system() is making a PM call, or CWSDPMI
is reflecting file closes to PM.


Rod Pemberton

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