On at 2023-08-26 16:30 +0200, C. Masloch via Freedos-user wrote:
Hello list,
I finished release 6 of lDebug (with a small L) today. This is my
advanced 86-DOS debugger project based on FreeDOS Debug/X (in turn based
on MS-DOS Debug), with some ideas from DR-DOS Debug. The duration since
the prior release 5 is back to less than 6 months as opposed to the year
between releases 4 and 5. Apart from the usual amount of bugfixes, there
are some new features.
I just found a bug in the release 6 revision of lDebug. It makes the DIL
command (Dump Interrupt chains with discovery of hidden chains through
AMIS Interrupt Lists) not work properly. Depending on the prior use of
(and left-over contents in) the auxiliary buffer, it could either seem
to appear to work, it could display an error immediately on any hidden
chain being detected (very common), or it could overflow the auxiliary
buffer (only possible if hundreds and hundreds of interrupt entrypoints
are found for one particular interrupt number).
It is unfortunate that this bug slipped by me into the release. I am
considering whether to make a "minor" release about it. As a halfway
remedy for now, I created a Script for lDebug that can patch an
uncompressed executable (ldebugu.com, ldebugxu.com, lcdebugu.com, etc)
to work around the bug. I have tested this patch on several different
files. It is described some on my blog [1]. A copy of the patch itself
is also hosted on our server [2]. The files that can be patched in the
FreeDOS package are found in the package's directory tree at these
positions:
SOURCE/LDEBUG/ldebug/bin/ldebugu.com
SOURCE/LDEBUG/ldebug/bin/ldebugxu.com
This is the complete script file:
=== snip patch6.sld
install flat
l
r v1 := bxcx >> 4
r v2 := 0
r v3 := bxcx
if (v1 <= 1000) then goto :small
r v2 := v1 - 1000
r v3 := 10000
:small
s cs+10+v2:0 l v3 B1 04 89 C3 D3 EB
if (src != 1) then goto :error
u srs:sro - 4 l 1
if (auo != sro) then goto :error
r v0 := word [srs:sro - 2]
s cs+10+400:0 l 10000 3B 3E byte v0 byte (v0 >> 8)
if (src != 3) then goto :error
a srs:sro0
cmp di, (8 * #1024 + #16 - #24)
.
a srs:sro1
cmp di, (8 * #1024 + #16 - #24)
.
a srs:sro2
cmp di, (8 * #1024 + #16 - #24)
.
w
goto :eof
:error
; Error detected
=== snip
This is how to use it:
* Run DOS command "ldebug ldebugu.com"
* Run lDebug command "y patch6.sld"
* Observe whether last line indicates "Error detected"
Regards,
ecm
[1]:
https://pushbx.org/ecm/dokuwiki/blog/pushbx/2023/0903_august/september_work#the_dil_bugfix
[2]: https://pushbx.org/ecm/test/20230902/patch6.sld
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