DOS ain't dead

CRITICAL OFF-by-32-KiB-BUG | Eric | LZMA2 (Users)

posted by DOS386, 10.04.2013, 12:00

(quoting Eric Auer):

> I just had an idea ... what if a pointer or counter is updated in a
> non- atomic way where some block count or the upper N bits could get
> updated concurrently while multi-threading, somehow skipping 32 k of data?

yeah ... I still suspect HX threading ... one is already confirmed: BUG

> I don't know all the details. LZMA2 is supposed to be better for
> multithreaded compression. Not sure about decompression

My archives causing the BUG were all created with 4.65 and LZMA1.

LZMA2 AFAIK should prevent excessive expansion on poorly compressible or incompressible data, apart from quad-core support not available in DOS anyway.

> When it run under DOS it's limited but under XP it can reach >2GB and maybe
> 4GB (on NTFS)

I got 21 GiB under EDR-DOS on FAT Anyway, I suspect that under XP the thread/interrupt hazard might NOT be able to occur the same way as it does in DOS.

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Complete thread:

• CRITICAL OFF-by-32-KiB-BUG - DOS386, 27.03.2013, 09:10 (Users)
  • CRITICAL OFF-by-32-KiB-BUG - RayeR, 28.03.2013, 02:16
    • CRITICAL OFF-by-32-KiB-BUG - DOS386, 29.03.2013, 09:26
      • CRITICAL OFF-by-32-KiB-BUG - RayeR, 29.03.2013, 11:02
        • CRITICAL OFF-by-32-KiB-BUG - DOS386, 29.03.2013, 11:19
          • CRITICAL OFF-by-32-KiB-BUG (threads) - DOS386, 31.03.2013, 17:42
            • CRITICAL OFF-by-32-KiB-BUG (threads) - RayeR, 03.04.2013, 12:35
              • CRITICAL OFF-by-32-KiB-BUG (threads) - Zyzzle, 04.04.2013, 04:17
                • CRITICAL OFF-by-32-KiB-BUG (threads) - RayeR, 04.04.2013, 13:51
              • CRITICAL OFF-by-32-KiB-BUG (threads) - DOS386, 04.04.2013, 04:37
  • CRITICAL OFF-by-32-KiB-BUG - Rugxulo, 05.04.2013, 19:15
    • CRITICAL OFF-by-32-KiB-BUG | Eric | LZMA2 - DOS386, 10.04.2013, 12:00