🚀 go-pugleaf

In article <FEIT.90Jul31140200@oswald.cs.odu.edu> feit@cs.odu.edu (Mark A. Feit) writes:
>A very nice bit of work to determine whether a drive exists or not.
>
>/* drive_is_valid()
> *
> * Determine if a drive (named by 'drive') exists or not.  If it's A or B,
> * go through the BIOS to see if it physically exists (avoiding DOS's "Insert
> * dist for drive B" messages).  Otherwise, go through DOS.
> *
> * Return Value:	DR_INVALID (0) if the drive is not valid.
> *			DR_VALID if Valid.
> *			Result will be ORed with DR_DONTREAD is the drive
> *			 is not able to be read bust exists anyway.
> */
>static int drive_is_valid( char drive )
>{
>  /* Code omitted for brevity. */
>}

The code works quite nicely in a non-networked environment.  I don't have
access to a Novell net, so the following comments may not apply in that
case.

In PC-NFS networks (using in my case the software sold by Sun Microsystems)
drives between the last physical drive, and drive 'V' are created by the
network driver, then 'mounted' from the file server.  This mount process
assigns remote file systems to any unused device in the list.  It is
therefore possible to have the following as the 'valid' device list:

    A: C: D: E: N: O: V:

(I.e. a floppy disk, 3-partition hard disk, "new software", "old software",
and network printer (pc-nfs uses drives t-v to map lpt1-3)).

Attempting to access an allocated but unmounted drive produces the dreaded
'Abort, Retry, Ignore' dialog.

The solution involves writing a dummy Critical Error Handler for DOS, that
always returns 'fail', instead of prompting the user.  I wrote one once,
but that project got shelved, and I can't lay my hands on the code at the
moment.  I'm sure one of the net.msdos.gods can provide details on how to
write the beast.  I seem to remember that MSC includes some type of support
but I can't remember.

If it's any consolation, the various WINDOWS versions we've played with
over the years don't even try to get it right.  They blithely display
drive K in the directory window, even though there is nothing mounted on
that drive.

--------------
Glenn Chambers                                  This is me speaking.
Intelligent Technology Group                    If my company were speaking,
Pittsburgh, PA.                                 my lips wouldn't be moving.
gchamber@nfsun.UUCP or ...!uunet!nfsun!gchamber