[OpenAFS-devel] AFS vs UNICODE

[Dave Botsch]

> 
> (1) The same text in Unicode can be represented by different sequences 
> of characters.  As a result you could have client A and client B both 
> create a file with the same name that can not be visually distinguished 
> by the end user.   Now which one do you open?

If everyone is using UTF-8 encoding, does the above problem still exist? And
by UTF-8, I mean the "real" UTF-8 encoding, not one of the many variants
(which would mean that the oafs client would have to do some translation)?

> 
> (2) Since the directory lookups are performed using a hash table, a file 
> with the name being searched for might exist but it cannot be found 
> because the input to the hash function on client B is different than the 
> input used to create the entry on client A.

It would be different because of #1 above?

> 
> Storing file names as opaque octet sequences is broken in other ways. 
> Depending on the character set used on the client the file name might or 
> might not be representable since the octet sequence contains no 
> indication whether the sequence is CP437, CP850, CP1252, ISO Latin-1,
> ISO-Latin-9, UTF-7, UTF-8, etc.
> 

So, if we know what sequence we're using...?

How do local filesystems handle this? I might very well create a file on my
ext3 filesystem usbkey with my locale set to ISO Latin-1 then try to access
it from another box with the charset set to UTF-16 (or something completely
different). Or maybe I named the file using some non-arabic character set?

I've read that Java uses a "modified UTF-8" which can cause there to be 6
instead of 4 octets per character... how does this not break other
applications from being able to access the files on the local filesystem?

> 
> 
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-- 
********************************
David William Botsch
Programmer/Analyst
CNF Computing
botsch@cnf.cornell.edu
********************************