Re: [PATCH] Posix file attribute support on VFAT

[Bodo Eggert <harvested.in.lkml@posting.7eggert.dyndns.org>]

Hiroyuki Machida <machida@sm.sony.co.jp> wrote:

> For newly created and/or modified files/dirs, system can utilize
> full posix attributes, because memory resident inode storage can
> hold those. After umount-mount cycle, system may lose some
> attributes to preserve VFAT format.

Inodes may be reclaimed, therefore you might also lose some attributes at
runtime. For your users, that will look like a heisenbug. A similar bug
has been reported for procfs. Is your implementation affected?

> - Special file
>         To distinguish special files, look if this fat dir entry 
>         has ATTR_SYS, first. If it has ATTR_SYS, then check
>         1st. LSB bit in ctime_cs, refered as "special file flag".
>         If set,  this file is created under VFAT with "posix_attr". 
>         Look up TYPE field to decide special file type.
>         This spcial file detection mothod has some flaw to make
>         potential confusion. E.g. some system file created under
>         dos/win may be treated as special file.  However in most case,
>         user don't create system file under dos/win.

You can add additional magic, e.g.: nodes must be empty, except for symlinks
which must be not larger than 4KB (current PATH_MAX?). This will get rid
of io.sys, logo.sys etc.\. If you want to be really sure, prepend a magic
code to the on-disk representation of symlinks.

-- 
Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF
verbreiteten Lügen zu sabotieren.