Stream names with colon don't work with fruit:encoding = native
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OS X makes extensive use of colons (':') in xattr names. On SMB mounts with streams support, xattrs are mapped to named streams and the client maps the colon character (as any other illegal NTFS character) to the Unicode private range.

This means by default on a Samba share with vfs_streams_xattr, the stream is again mapped to a xattr and the colon in the xattr name is stored as an UTF8 encoded Unicode private range character. So far things work correct. :)

Example:

samba$ $ grep -A 3 '\[AAPL' /opt/samba/etc/smb.conf
[AAPL]
    path = /Volumes/aapl
    vfs objects = catia fruit streams_xattr
#    fruit:encoding = native

mac$ mount_smbfs -o nobrowse //fedora20.local/aapl mnt
mac$ touch mnt/file
mac$ xattr -w 'foo:bar' baz mnt/file 
mac$ xattr -l mnt/file
foo:bar: baz
mac$ 

samba$ getfattr /Volumes/aapl/file
getfattr: Removing leading '/' from absolute path names
# file: Volumes/aapl/file
user.DOSATTRIB
user.DosStream.foobar:$DATA

vfs_fruit can enable a builtin vfs_catia mapping (requires vfs_catia to be loaded of course) that maps the illegal NTFS characters between their mapped private range and the native ASCII representation. This applies both to filenames as well as xattr names, examples:

samba$ $ grep -A 3 '\[AAPL' /opt/samba/etc/smb.conf
[AAPL]
    path = /Volumes/aapl
    vfs objects = catia fruit streams_xattr
    fruit:encoding = native

mac$ mount_smbfs -o nobrowse //fedora20.local/aapl mnt
mac$ touch mnt/file
mac$ xattr -w 'foo:bar' baz mnt/file 
mac$ xattr -l mnt/file
foo:bar: baz
mac$ 

samba$ getfattr /Volumes/aapl/file
getfattr: Removing leading '/' from absolute path names
# file: Volumes/aapl/file
user.DOSATTRIB
user.DosStream.foo:bar:$DATA

We have two issues with this:
- we don't perform the reverse mapping from native ASCII to the private range when enumerating streams in getinfo calls
- vfs_streams_xattr uses strchr_m(':') instead of strrchr_m(':') at one point when looking for the streamname:streamtype seperator which won't work if the streamname contains a colon

Patches including a torture test are pending.