On Jan 23, 2008, at 1:41 AM, Mike Hommey wrote:

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> On Tue, Jan 22, 2008 at 08:33:25PM -0500, Theodore Tso wrote:
>> On Tue, Jan 22, 2008 at 04:38:37PM -0800, Linus Torvalds wrote:
>>> One thing I'd like somebody to check: what _does_ happen with OS X =20=

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>>> and NFS
>>> (OS X as a client, not server)? In particular:
>>>
>>> - Is it suddenly sane and case-sensitive?
>>
>> Using a Linux server, and a OS X client, over NFS, it is in
>> case-sensitive.  This is not unexpected, since you can mount UFS
>> partitions on Mac OS X, or reformat HFS+ filesystems and make them be
>> case-sensitive.
>>
>>> - Does the NFS client do any unicode conversion?
>>
>> Nope:
>>
>> # perl -CO -e 'print pack("U",0x00C4)."\n"'  | xargs touch
>> # ls -l | cat -v
>> total 0
>> 0 -rw-r--r--   1 nobody  nobody  0 Jan 22 20:30 M-CM-^D
>>
>> It's pretty clear the Unicode conversion is being done in HFS+, not =20=

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>> in
>> the VFS layer of Mac OS X.
>
> There must be something at the VFS layer, or some other layer:
> - IIRC, Joliet iso9660 volumes end up being mounted with files names =20=

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> in
>  NFS when the real file names are NFC on the disk.

I assume you mean NFD, not NFS, but here's what one of the HFS+ =20
engineers had to say:

"In Mac OS X,  SMB, MSDOS, UDF, ISO 9660 (Joliet), NTFS and ZFS file =20
systems all store in one form -- NFC.  We store in NFC since that what =20=

is expected for these files systems."

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> - Likewise for Samba shares.

See above.

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> - When I had my problems with iso9660 rockridge volumes using NFC (you
>  can create that just fine with mkisofs), the volume is mounted =20
> without
>  normalisation, i.e. if you get to a shell and want to access files,
>  you must use NFC, but at least the Finder does transliteration at =20
> some
>  stage, because going into the mount point and opening some files fail
>  because it's trying to open the file with the name transliterated to
>  NFD. I just hope the same doesn't happen with other filesystems.

Can you produce a reproducible set of steps for this? Because the =20
Finder shouldn't be doing any of this work on its own, all the =20
normalization stuff happens directly in HFS+.

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> Also, OSX using NFD widely, a file created from non Unix applications
> may end up being named in NFD on any file system. File contents, too,
> may end up being transliterated whenever a file is modified with non
> Unix applications, introducing unwanted changes.
> Typing file names in the Terminal might also make them encoded in NFD,
> too.

Entirely possible, though renormalizing file contents seems a bit less =20=

likely. I will point out that the text input system in OS X seems to =20
default to producing NFC (at least, typing `echo 'M=E4rchen' | xxd` in =20=

the Terminal shows that the input string there is NFC). So user input =20=

will most likely produce NFC, the only way you're probably going to =20
end up with NFD is if you move a file from HFS+ to another filesystem.

-Kevin Ballard

--=20
Kevin Ballard
http://kevin.sb.org
kevin@sb.org
http://www.tildesoft.com