Date: Wed, 8 Nov 2000 09:05:23 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender: eliz AT is
To: James Owens <ad354 AT FreeNet DOT Carleton DOT CA>
cc: djgpp AT delorie DOT com
Subject: Re: InfoZIP vol label: force it, but please advise
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On 7 Nov 2000, James Owens wrote:

> By commenting out some code I can get the compiled UNZIPSFX.EXE to label
> the floppy.  The original code causes the program to skip the labelling:
> 
>     if (uO.volflag == 0 || *buildpath < 'a' || /* no label/bogus disk */
>        (uO.volflag == 1 && !isfloppy(nLabelDrive))) /* -$:  no fixed */
> 
> If I comment out the second line it works, so either the -$ parameter is
> not setting u0.volflag, or isfloppy() is returning the wrong result. (I
> guess).

The easiest way to know for sure is either to run the program under a
debugger, put a breakpoint on this line, and print the value of both
uO.volflag and isfloppy(nLabelDrive); or use printf to show those
values.

I would also look at the value of nLabelDrive: it should be 1 for
drive A:, 2 for B:, etc.

> I don't understand isfloppy() at all, but it's short. Please tell me if
> you can see anything wrong.

`isfloppy' is not wrong.  It calls function 4408h of Int 21h, which
returns 0 in AX if the drive media is removable, 1 if it is fixed.
You should see the same DOS call in action if you call the DJGPP
library function `getmntent' and print the mnt_type member of the
struct that it returns: it should say "fd" for a floppy disk.

In fact, comparing the results of `getmntent' and `isfloppy' for the
same floppy drive might tell you whether something's subtly wrong in
InfoZip's implementation (it uses some macros whose definition I can
only guess).

But the most direct evidence for the cause of the problem is to see
what do uO.volflag and `isfloppy' actually return.

Also, please be *absolutely* sure that the second line is indeed the
cause of the problem.  For example, the test "*buildpath < 'a'" seems
bogus to me (what if the drive letter is 'A'?).