DOS ain't dead - new HACKWRAP fix for MS-DOS7+, aka smashing the bug

new HACKWRAP fix for MS-DOS7+, aka smashing the bug (Miscellaneous)

posted by Ninho , 17.12.2009, 16:35

> Since you're going to make DOS take the jump, why not just change the
> jump? The bit is redundant.

The more I think of it the more I'm happy with the dual bit option. They play a different role than each other and work together nicely.

The MAGIC_Bit which we patch inside of the DOS kernel signals that the bug fix has been applied; Ninho's flag bit in DOS Data is what is used to SWITCH the fix on and off as instructed per DEVICE=HACKWRAP.SYS directives.

Now examine all the combinations of MAGIC and SWITCH and what they signify to us when we are launching "DEVICE=HACKWRAP ON ".

CASE 00: MAGIC_Bit and Ninho_SWITCH BOTH zero : the DOS is still unpatched (buggy!), this must be the first instance of HACKWRAP, so patch-in the fix and switch Fixwrap on (Set bits to 11)

CASE 10: MAGIC is ON but SWITCHed OFF : the bug fix was applied, but the command bit os off. Maybe there has been a succession of HACKWRAP=ON/OFF invoocations, to be expected if e.g. you have a complex CONFIG.SYS with [MENU] and INCLDE=... directives.

This case may also happen on the first invocation of FIXWRAP, if the IO.SYS file had the MAGIC permanently patched in.

Action : switch Fixwrap ON again. (->11)

CASE 11: Both bits ON : Fixwrap already active, leave as is =11). Warn, no error.

CASE 01: DOS unpatched yet but Ninho's SWITCH bit was ON : is an ERROR. Other software has "owned" Ninho's bit, YELL! and quit. Better not declare war on an unidentified enemy. :-)

I think things are turning out quite nicely. We'll be taking off ASAP....

---
Ninho

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Complete thread:

new HACKWRAP fix for MS-DOS7+, aka smashing the bug - Ninho, 11.12.2009, 00:17 (Miscellaneous)
- new HACKWRAP fix for MS-DOS7+, aka smashing the bug - ecm, 11.12.2009, 15:02
  - new *FIXWRAP* for MS-DOS7+, aka smashing the bug - Ninho, 12.12.2009, 01:12
- FIXWRAP technical thread. News - Ninho, 12.12.2009, 16:05
  - CM's questions, answered - Ninho, 12.12.2009, 18:22
    - CM's questions, answered - ecm, 12.12.2009, 22:40
      - CM's questions, answered - Ninho, 13.12.2009, 00:10
        CM's questions, answered - ecm, 13.12.2009, 00:51
        CM's questions, answered - Ninho, 13.12.2009, 10:32
    - CM's questions, answered - geoffchappell, 14.12.2009, 10:42
      - CM's questions, answered - Ninho, 14.12.2009, 12:19
- new HACKWRAP fix for MS-DOS7+, aka smashing the bug - geoffchappell, 14.12.2009, 10:41
  - new HACKWRAP fix for MS-DOS7+, aka smashing the bug - Ninho, 14.12.2009, 11:49
    - new HACKWRAP fix for MS-DOS7+, aka smashing the bug - geoffchappell, 15.12.2009, 16:55
      - new HACKWRAP fix for MS-DOS7+, aka smashing the bug - Ninho, 15.12.2009, 19:08
      - new HACKWRAP fix for MS-DOS7+, aka smashing the bug - Ninho, 17.12.2009, 16:35
- the DOS code segment hunt, results/questions - Ninho, 14.12.2009, 20:37
  - the DOS code segment hunt, results/questions - ecm, 14.12.2009, 23:30
    - the DOS code segment hunt, results/questions - Ninho, 15.12.2009, 00:59
    - Aha! Share was a *red herring* ! Hunt over !!! - Ninho, 15.12.2009, 10:32
      - Aha! Share was a *red herring* ! Hunt over !!! - ecm, 15.12.2009, 21:13
        Aha! Share was a *red herring* ! Hunt over !!! - Ninho, 15.12.2009, 22:32
        Aha! Share was a *red herring* ! Hunt over !!! - ecm, 15.12.2009, 23:05
    - the DOS code segment hunt, results/questions - geoffchappell, 15.12.2009, 16:56
      - the DOS code segment hunt, results/questions - ecm, 15.12.2009, 21:19
        the DOS code segment hunt, results/questions - Ninho, 15.12.2009, 22:38
        the DOS code segment hunt, results/questions - ecm, 15.12.2009, 23:06
        the DOS code segment hunt, results/questions - Ninho, 16.12.2009, 09:22
      - the DOS code segment hunt, results/questions - Ninho, 16.12.2009, 20:24
        the DOS code segment hunt, results/questions - Ninho, 30.12.2009, 10:50
  - the algorithm, sketched for review. Nitpicks ? - Ninho, 16.12.2009, 19:51
    - the algorithm, sketched for review. Nitpicks ? - ecm, 17.12.2009, 16:19
      - the algorithm, sketched for review. Nitpicks ? - Ninho, 17.12.2009, 17:14
        the algorithm, sketched for review. Nitpicks ? - ecm, 17.12.2009, 20:32
        the algorithm, sketched for review. Nitpicks ? - Ninho, 17.12.2009, 21:05
        the algorithm, sketched for review. Nitpicks ? - ecm, 17.12.2009, 21:13
        the algorithm, sketched for review. Nitpicks ? - Ninho, 17.12.2009, 23:16
        digression : MSDOS 7 and SHARE.EXE revisited - Ninho, 18.12.2009, 13:04
        digression : MSDOS 7 and SHARE.EXE revisited - ecm, 18.12.2009, 14:31
        digression : MSDOS 7 and SHARE.EXE revisited - Ninho, 18.12.2009, 17:19
        digression : MSDOS 7 and SHARE.EXE revisited - ecm, 18.12.2009, 18:19
        digression : MSDOS 7 and SHARE.EXE revisited - Ninho, 18.12.2009, 18:55
- HACKWRAP.SYS news, testing - Ninho, 20.12.2009, 02:44
  - FIXWRAP.SYS 0.5 beta - released - please try it ! - Ninho, 23.12.2009, 00:07