aclAn ACL structure type.
mode_pIf the pointer mode_p is not NULL, the
value pointed to by mode_p is set to the value
that defines the same owner/group/other permissions as contained in
the ACL.
is_not_equiv_pIf the pointer is_not_equiv_p is not
NULL, the value pointed to by is_not_equiv_p is
set to 0 (the acl is an equivalent ACL) or 1
(the acl is not an equivalent ACL).