Re: [nfsv4] re: ACL and Posix Mode bit interaction

[rick at snowhite.cis.uoguelph.ca]

>   I believe you mean "no ACL" use the mode-bits.
Yes, I meant "no ACL". The problem is "How does a server express no ACL"?
(I suggested "empty ACL" -> "no ACL", but agree that isn't ideal.)

> Rick seems to think there is no such thing as "no acl."  I'm not convinced:
> 
>    The server must return an error
>    if it supports an attribute but cannot obtain its value.  In that
>    case no attribute values will be returned.

Jim is correct that I had assumed that a Getattr Op must return an ACL, if
requested and the server supports ACLs. (It also seemed that Andreas and Bruce
read it that way, from the recent thread.) Now that I've read para 2 of
DESCRIPTION in sec. 14.2.7 again, I'm not so sure.

   The server must return a value for each attribute that the client
   requests if the attribute is supported by the server.  If the server
   does not support an attribute or cannot approximate a useful value
   then it must not return the attribute value and must not set the
   attribute bit in the result bitmap.  The server must return an error
   if it supports an attribute but cannot obtain its value.  In that
   case no attribute values will be returned.

The second sentence seems to contradict the first for the case "cannot
approximate a useful value", which is exactly what I'd call the "no ACL"
case. Then the third/fourth sentences seems to contradict the second, saying it
must return an error instead of the bitmap with the bit not set?

If you believe that the server must return an ACL, then your choices seem
to be:
- return an empty ACL for "no ACL"
OR
- generate a fake one, which then leads to the POSIX Mode->ACL mapping
  exercise that just never seems to get settled.

But, yes I meant "no ACL" and, for want of a better way to express it,
selected "empty ACL" -> "no ACL".

rick

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