OpenEuphoria

Re: [OT] files/dir on windoze

• Posted by "Kat" <gertie at visionsix.com> Jul 08, 2004
• 554 views

On 8 Jul 2004, at 22:11, Juergen Luethje wrote:

> 
> 
> Kat wrote:
> 
> <big snip>
> 
> > Thanks for duplicating the bug, Juergen. By any chance did it stop you from
> > using the computer for anything else before you got out of that crashed
> > filename program?
> 
> I noticed that other programs worked slower than normally. I think this
> is nothing special, because the Eu program needs some CPU time, and
> writing to disk isn't a fast process. But the program didn't stop me
> from using the computer for anything else.
> 
> > I have a suspicion this is related to the total bytecount of the filenames
> > and
> > the allowed space in the FAT per directory.
> 
> In the meantime, I have the same suspicion.
> 
> > It occured with me using LFN on
> > win95B, on a 15gb  FAT32 partition. Keep in mind the bytecount of the
> > filename may be higher than the filename as displayed to you.
> 
> Absolutely. I made some tests in the root directory of a 1.4 MB floppy
> disk (e.g. 9+3 means a filename such as '123456789.txt'):
> 
> length of filenames     max. number of files
> -------------------     --------------------
>  1+3                     112
>  ..
>  9+3                     112
> 10+3                      74
>  ..
> 22+3                      74
> 23+3                      56
> 
> Maybe someone can discover the appropriate formula, how much bytes are
> actually occupied by a filename, depending on the number of its
> characters. It might look somehow like this:
>    occupiedBytes = ceil(numberOfCharacters/a)*a + b
> 
> Maybe a similar formula would apply to subdirectories on a hard disk?

Last i saw (for win9x), it was 
name = space
1.0 = 8.3
8.3  = 8+3
9.3  = 7+flagbyte+3+8.3
15.3 = 7+flagbyte+3+8.3
16.3 = 7+flagbyte+3+7+flagbyte+3+8.3

The other catch is one filename can consume a whole cluster, even if only 
10.3 long. Floppies are different than harddrives in that regard.

Basically, if x in x.y is over 8, remove the last byte (making 7 remaining), 
replace the last byte space with a flag byte (a normally illegal char), put the 
last byte in the next 8.3 space. It's a crude hack, yes. It also makes it 
possible to use non-LFN apps to overwrite LFN files if the filename isn't 
changed. Backwards compatability and all that. I don't know about the 
FAT32 drives. FAT32 in win9x is probably all different than w2k, ME, and xp.

Kat