Changes to SFTP v6: change in acl present flag

[Joseph Galbraith <galb-list%vandyke.com@localhost>]

Do we have people already shipping SFTP v6
style attributes?

Implementation experience has just taught me that
I need both the boolean acl-present and the count field
in the ACL.

Even when the access control part of the acl is not
present, there still may be auditing / system alarm
entries present.

I propose changing the current text to the following:

> If the 'acl-present' flag is not set, it indicates that
> the file does not have an ACL, as opposed to having an
> empty ACL.  An empty ACL grants no access, not having
> an ACL grants all access. This is distinct from the
> case of SSH_FILEXFER_ATTR_ACL not being present in the
> attrib flags. If SSH_FILEXFER_ATTR_ACL is not present,
> the client can not deduce whether the server does not
> support ACLs, did not check the ACL (because doing
> so was expensive), or had some other reason for
> omitting the data.
>
> When the 'acl-prenent' flag is not set, there may still
> be system audit or alarm type entries in the list.

Thanks,

Joseph