DOS ain't dead

FPC 2.6.2 released (Announce)

posted by Arjay, 19.03.2013, 01:48

> > 2)
> > Again occured weird problems with environment settings when shelling
> into
> > DOS. Under W98 it cuts some environment variables.
>
> The only difference I see here is TMP and TEMP missing. Maybe that's
> intentional for some reason, dunno.

I noted the damaged environment starts with the new string "D:\WINDOWS\COMMAND.COM" which is 22 bytes long. Comparing that to the undamaged environment, it appears that this is an size/alignment issue when "patching" the environment under W98 since the P of TEMP variable is infact still present but has the first 3 bytes of it overwritten. The environment uses nul terminated strings between strings. Comparing environments:

1234567890123456789012345
TMP=D:\WINDOWS\TEMP
TEMP=D:\WINDOWS\TEMP
vs
1234567890123456789012345
D:\WINDOWS\COMMAND.COM
P=D:\WINDOWS\TEMP

The string "TMP=D:\WINDOWS\TEMP" is 19 bytes in length, with 3 bytes missing off the next variable TEMP (TEM) = 22 in total. Or to write it another way which should help show exactly what I am talking about:
1234567890123456789012345
TMP=D:\WINDOWS\TEMP TEMP=D:\WINDOWS\TEMP
D:\WINDOWS\COMMAND.COM P=D:\WINDOWS\TEMP

I have further thoughts but am too tired to write something sensible now.

Complete thread:

• FPC 2.6.2 released - marcov, 26.02.2013, 10:09 (Announce)
  • FPC 2.6.2 released - Rugxulo, 27.02.2013, 10:49
    • FPC 2.6.2 released - marcov, 28.02.2013, 13:46
      • FPC 2.6.2 released - Rugxulo, 28.02.2013, 20:43
        • FPC 2.6.2 released - Rugxulo, 02.03.2013, 18:57
          • FPC 2.6.2 released - marcov, 03.03.2013, 00:21
            • FPC 2.6.2 released - Rugxulo, 03.03.2013, 02:36
              • FPC 2.6.2 released - marcov, 04.03.2013, 22:23
          • FPC 2.6.2 released - Rugxulo, 14.03.2013, 17:16
            • FPC 2.6.2 released - Rugxulo, 28.03.2013, 00:35
    • FPC 2.6.2 released - rr, 03.03.2013, 21:08
  • FPC 2.6.2 released - Laaca, 18.03.2013, 12:00
    • FPC 2.6.2 released - Rugxulo, 19.03.2013, 00:08
      • FPC 2.6.2 released - Arjay, 19.03.2013, 01:48
      • FPC 2.6.2 released - Laaca, 19.03.2013, 11:40
        • FPC 2.6.2 released - Rugxulo, 21.03.2013, 17:26