vfs: add vfs_shell_snap module
The shell_snap VFS module plumbs into the snapshot (aka shadow-copy)
management paths used by Samba's File Server Remote Vss Protocol (FSRVP)
server.
The following shell callouts may be configured in smb.conf:
shell_snap:check path command
- Called when an FSRVP client wishes to check whether a given
share supports snapshot create/delete requests.
- The command is called with a single <share path> argument.
- The command must return 0 if <share path> is capable of being
snapshotted.
shell_snap:create command
- Called when an FSRVP client wishes to create a snapshot.
- The command is called with a single <share path> argument.
- The command must return 0 status if the snapshot was
successfully taken.
- The command must output the path of the newly created snapshot
to stdout.
shell_snap:delete command
- Called when an FSRVP client wishes to delete a snapshot.
- The command is called with <base share path> and
<snapshot share path> arguments.
- The command must return 0 status if the snapshot was
successfully removed.