Re: PATCH to access old-style FAT fs

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

"H. Peter Anvin" <hpa@zytor.com> writes:

> Followup to:  <20040126173949.GA788@frodo.local>
> By author:    Frodo Looijaard <frodol@dds.nl>
> In newsgroup: linux.dev.kernel
> > 
> > Hi folks,
> > 
> > I have created and attached a new version of my old-style FAT filesystem
> > patch, this time for the 2.6.0 kernel. It can also be found on
> > http://debian.frodo.looijaard.name/. 
> > 
> > Some old implementation of the FAT standard mark the end of the
> > directory file index by inserting a filename beginning with a byte 00.
> > All entries after it should be ignored, even though they are not marked
> > as deleted. At least some EPOC releases (an OS used on Psion PDAs, for
> > example) still use this policy.
> > 
> 
> It's not just "old implementations" -- it's the spec.
> 
> After reaching a filename beginning with 00, no further data should be
> assumed to be in that filesystem.  MS-DOS itself would only do that
> when formatting the filesystem, so *all* the subsequent entries would
> be assumed to start with 00, but that doesn't really seem to be to
> spec.

The new cluster for directory entries must be initialized by 0x00.
And, when the directory entry is deleted, the name[0] is updated by
0xe5 not 0x00.

So, if the name[0] is 0x00, it after, all bytes in cluster is 0x00.

The fat driver can stop at name[0] == 0x00, but this is just optimization.
The behavior shouldn't change by this.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>