DOS ain't dead - UI21DEB deBUGGER released

UI21DEB deBUGGER released | the mess (Announce)

posted by ecm , Düsseldorf, Germany, 01.03.2009, 10:40

> > your TSR handle allow the debugger to single step into Int 21 without
> causing a mess
>
> There is no mess at all ... just a tiny problem that the IRET
> supposed to jump back into the app jumps into garbage instead

This is the whole mess.

> and I have no idea why :confused:

Because your hook is inreentrant and JDEBUG ;-) uses Int21 as long as the InDOS flag is not set. The traced Int21 call then probably returns into DEBUG (I think DEBUG last calls Int21.40 [write LF after Int21.0A], or Int21.50 [set PSP to debuggee's if the SDA is not used]). The solution is to set up a reentrant stack frame to get the flags, and set up your own "InUI21DEB" flag. If that is set when entering the handler, completely skip to where you chain to the old handler.

---
l

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Complete thread:

UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 20.02.2009, 05:53 (Announce)
- UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 20.02.2009, 06:19
  - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - ecm, 20.02.2009, 20:19
    - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 24.02.2009, 06:02
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Laaca, 24.02.2009, 10:28
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - rr, 24.02.2009, 21:43
        UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 25.02.2009, 03:06
        UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - ecm, 25.02.2009, 13:15
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Japheth, 25.02.2009, 14:09
        UI21DEB deBUGGER released | the mess - DOS386, 01.03.2009, 08:24
        UI21DEB deBUGGER released | the mess - ecm, 01.03.2009, 10:40
        UI21DEB deBUGGER released | inreentrant mess - DOS386, 01.03.2009, 13:59
        UI21DEB deBUGGER released | inreentrant mess - ecm, 01.03.2009, 16:19
        UI21DEB deBUGGER released | inreentrant mess - Japheth, 02.03.2009, 07:48
        UI21DEB deBUGGER released | inreentrant mess - ecm, 02.03.2009, 15:28
        UI21DEB deBUGGER released | inreentrant mess - Japheth, 03.03.2009, 07:52
        UI21DEB deBUGGER released | crappy and incrappy stuff - DOS386, 15.03.2009, 02:39
        UI21DEB deBUGGER released | crappy and incrappy stuff - Japheth, 15.03.2009, 08:17
        UI21DEB deBUGGER released | crappy and incrappy stuff - ecm, 15.03.2009, 21:02
  - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Laaca, 20.02.2009, 20:21