advapi32: Handle NULL DACL in SetSecurityInfo

[Erich E. Hoover]

On Thu, Apr 2, 2015 at 4:54 PM, Piotr Caban <piotr at codeweavers.com> wrote:
> ...
> the patch restores old SetSecurityInfo behavior. It also works around a
> crash in current implementation when NULL DACL is passed. It's as close to
> native behavior as it currently can be. Setting NULL DACL means: allow every
> permission on windows. Your test shows that we should get NULL while asking
> about DACL but there's no way of correctly supporting it in wine currently
> (and I'm not sure if it can be cleanly supported in future, as far as I can
> see nor POSIX ACL, nor NFSv4 ACL supports anything like this).
> ...

This is one of the reasons why in our implementation we stored the
security descriptor in an extended filesystem attribute.  Samba
encountered the same problems with a lot of the win ACLs, they found
that for some things the only way to provide full support is to store
a perfect copy of the security descriptor.  Doing so works around a
lot of these issues where there's no equivalent Unix permission.

Best,
Erich