Displaying streams as xattrs

Steve French smfrench at gmail.com
Thu May 25 20:11:13 UTC 2023

On Thu, May 25, 2023 at 11:22 AM Jeremy Allison <jra at samba.org> wrote:
> On Thu, May 25, 2023 at 08:49:47PM +1000, ronnie sahlberg wrote:
> >>
> >> just took a look at how the ntfs-3g module is handling this. It was an option
> >> streams_interface=value, which allows "windows", which means that the
> >> alternative data streams are accessable as-is like in Windows, with ":" being
> >> the separator. This might be a nice option for cifsfs also. That option would
> >> just be usable if no posix extensions are enabled of course.

You can already open alternate data streams remotely (from cifs.ko on Linux
as you can from Windows and Macs etc. just open "file:streamname"), but on
Linux you have to disable the reserved character mapping ("nomapposix")
otherwise ":" would get remapped on open in the Unicode conversion.

There may be a better way to list streams in the future (e.g. to help
backup applications
that need to be able to save files created by Macs or Windows that need these
e.g. Virus checkers etc. use ADS, and looking at my Windows machines, PDFs
can have small "Zone Identifiers" saved in streams), but you can
already list them
with "smbinfo filestreaminfo <filename>"

I was thinking mainly about backup scenarios whether this came up as
listing them
also via a pseudo-xattr (IIRC Macs do something similar).



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