Possible bug in FAT dir listing
gds at chartertn.net
Tue Jan 13 23:45:51 CST 2009
I formatted an MMC card on linux with gparted as FAT16. I copy one file
to it called freddy.txt I unmount and dump the partition with dd. The
root directory entry appears like this:
003d5f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
003d600: 4166 0072 0065 0064 0064 000f 0055 7900 Af.r.e.d.d...Uy.
003d610: 2e00 7400 7800 7400 0000 0000 ffff ffff ..t.x.t.........
003d620: 4652 4544 4459 2020 5458 5420 0000 9100 FREDDY TXT ....
003d630: 2e3a 2d3a 0000 6eb5 2c3a 0300 1300 0000 .:-:..n.,:......
003d640: 0000 0000 0000 0000 0000 0000 0000 0000 ................
There are two entries. One starts with A and seems to be unicode of some
sort (32 bytes at 3d600) while the 2nd is conventional ASCII and is 32
bytes at 3d620.
When I mount on rtems and do ls in the shell I see this:
[/mnt] # ls
The entry that starts with A shows up as "Af". From what I have read it
should actually be ignored and not printed because the byte at 3d60b is
0x0f. The 0x0f is the file attributes indicating this is a volume label,
system file, hidden file and read-only. This is a key that it should not
be displayed. (Why this filename gets put in I don't know. I think
windows does the same.)
Both of these sites mention that the attribute flag 0xf means don't show
This also explains why a volume label shows up as a file in rtems when
doing ls. It should be ignored too.
AFAICT, there is no code in the rtems FAT library to ignore files when
these attribute flags are set. I only see the "directory" attribute
checked in some places.
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