Re: [Info-mtools] Inconsistent results between kernel vfat and mtools

[G.W. Haywood]

Hi there,

On Tue, 21 Nov 2023, Pali Rohár wrote:

> On Tuesday 21 November 2023 14:08:30 G.W. Haywood wrote:
> > Also I'm kinda puzzled why some of the file extensions are shown in lower case.
>
> Hello, for FAT directory entry since LFN extension was introduced, there
> is one byte (called NT byte) used for some flags and one bit in this
> byte is interpreted as name is lowercase and other bit in this byte as
> extension is lowercase. So you can have uppercase name with lowercase
> extension without need to fill additional FAT LFN entry for that file.

Thanks, I wasn't aware of that bit of the history. :)

> So my guess is that specific bit is set and mdir interpreted it. This
> can happen also for FAT filesystem which are pre-LFN and this bit was
> used for something different (application or system specific).

What I meant puzzled me, though, was that the file extensions were mixed
on the same image.  I'd sort of expect that whether upper or lower case
they would all be the same.  But I guess your explanation would cover it
if there have indeed been application-specific uses of the 'NT byte' for
this particular image.  Or it's just been trashed. :/

--

73,
Ged.