OS X - how to calculate normalized file name

Question

I need to create a mapping between file names generated on Windows and OS X. I know that OS X \"converts all file names to decomposed Unicode\" however, \"most volume forma

Answer 1

According to your link, filesystem drivers appear to (mostly) follow one of two behaviours: * Return all names in NFD, and convert names as appropriate. * Don't perform any conversions.

In both these cases, if you create a file on OSX in NFD, reading it back on OSX should give you the name in NFD.

OTOH, if your filename goes from Windows → NFS → Mac and you want to do some sort of sync, you're out of luck. This is not an easy thing to do, since the underlying problem is a little philosophical: Should filenames be byte strings or Unicode strings? I believe Unix traditionally does the former, and at least in Linux, UTF-8 NFC names are merely a convention.

(It gets worse, since IIRC HFS+ is defined to use Unicode 3.something, so a naïve conversion to NFD might be wrong for characters added/changed since then unless the API you use can guarantee a specific Unicode version.)