[PATCH] smbd: Fix snapshot query on shares with DFS enabled

[Jeremy Allison]

On Wed, Aug 17, 2016 at 01:19:11PM -0700, Jeremy Allison wrote:
> 
> Ah ok - that's the missing piece ! I'd prefer the /server/share/path/to/file/@GMT-xxx
> approach as that prevents us having to mess understand when we have
> a DFS vs. regular path.
> 
> I'm assuming the above also works with Windows ? I'm having
> trouble on my W2K12R2 box getting @GMT paths to work with SMB1.

Ah ! Yes it does. Just found in MS-SMB:

-----------------------------------------------------------------
2.2.1.1.1 Pathname Extensions

Pathnames are allowed to contain a previous version token (or @GMT token), as a directory
element in a path. A previous version token indicates that the pathname is a request to access the
previous version (or shadow copy) of the file or directory at a particular point in time. This feature
is available on any path-based operation (for example, SMB_COM_NT_CREATE_ANDX). A pathname
MUST NOT contain more than one previous version token.
For example, requesting a previous version of the file \\server\mydocs\reviews\feb01.doc at
2:44:00 P.M. on March30, 2001 UTC is specified in the following format:
\\server\mydocs\reviews\@GMT-2001.03.30-14.44.00\feb01.doc
The same technique can be used to build a path that represents a previous version of a directory as
opposed to a file.
For example, requesting a previous version of the directory \\server\mydocs\reviews at 2:44:00 PM
on 3/30/01 UTC can be specified in either of the following formats:
A token appearing as an intermediate path component:

\\server\mydocs\@GMT-2001.03.30-14.44.00\reviews

A token appearing as a final path component:

\\server\mydocs\reviews\@GMT-2001.03.30-14.44.00
-----------------------------------------------------------------