Re: Re: Moving a directory into another fails

[Linus Torvalds <torvalds@osdl.org>]

On Mon, 4 Dec 2006, Linus Torvalds wrote:
> 
> If a filesystem cannot represent that name AS THAT BYTE SEQUENCE then the 
> filesystem is broken. No ifs, buts, maybes about it. I'm sorry, but that's 
> how it is.

Btw, what this means in practice is that when git creates a file with a 
certain sequence of bytes, then 
 (a) readdir had better return _that_ sequence of bytes, or git will see 
     it as somethign else.
 (b) opening it with that same sequence of bytes had better work.

This does not mean that a filesystem may not internally use some other 
encoding. It just means that if the filesystem - when converting back and 
forth between the internal encoding and the one it shows to user space - 
had better convert back to the exact same thing.

Also, note that for most projects, even a broken filesystem doesn't 
actually matter - it's enough that the filesystem gets the conversions 
right for the particular set of names in a particular project. So any 
project that just has 7-bit filenames will obviously never even see any 
issues at all, even if the filesystem it runs on then does something 
strange with 8-bit filenames.

This is one reason why UNIX's "everything is a stream of bytes" is so 
important, and whyprograms should generally work with byte streams, not 
"wide strings" or similar. It's the only way that you can reliably work 
across different locales. Use wide strings and locale-specific stuff 
_only_ for actually showing users something on the tty, for example.