It turned out that this loader was severely broken for many years,
at least since 2012 (the git repo's creation). This variable was
read as a word to set cx for a loop, but only the low byte had
been written. The high byte happened to be 0EEh so cn_loop would
always zero out the FAT sector to read.
This _happened_ to work if the first root directory cluster and
all the kernel file clusters were all referenced in the first
sector of the FAT. Otherwise it would blow up.
Picked from the commit at fe1c4dc7fe
The referenced issue is at https://github.com/dosemu2/fdpp/issues/212
The patch was applied using unix2dos on the patch file
then `patch -p1 --binary` with the patch file as stdin.
The original used a new define for the maximum path length.
As there is no difference to our current SFTMAX define I
changed this hunk to retain the SFTMAX use.
This fixes a bug when eg function 3Dh receives a buffer
that starts with ".\" but the byte in memory before this
buffer happens to be also a dot. I ran into this problem
semi-randomly during building EDR-DOS with the most recent
WarpLink build. If WarpLink was placed somewhat low in the
Low Memory Area then one of its function 3Dh calls would
happen to have a dot before the pathname buffer. (I had to
load lCDebug using the last fit strategy then enter TSR mode,
to catch the bug without the presence of the debugger working
around the occurrence of the bug.)
Original commit Metadata:
From: Stas Sergeev <stsp@users.sourceforge.net>
Date: Wed, 1 Feb 2023 13:01:55 +0500
Subject: [PATCH] truename: fix array overrun [fixes#212]
src[-2] was peeking into a random memory location.
It seems entire truename() is written by some morons... :(
Its completely unreadable and full of bugs.
lDebug wants to access the environment while executing
as a device driver. Instead of building it in a variable
then copying it to 68h:0 after FDCONFIG.SYS processing,
just build it there to begin with.
To be able to return free space on larger non local disks, the redirector
needs an extension. Dosemu2 has implemented this function and FDPP
has an almost identical patch to this. If the extension is not
implemented by your chosen redirector, then fallback to the standard
110c function is done for int21/7303.
With this patch up to 2TB (with Dosemu2 reporting in 512 blocks) can be
displayed.
Also checks that the total amount of clusters is possible
for the detected file system, erroring out otherwise.
Small FAT32 is displayed in the verbose output specifically.
