[Zope] Proxy role bug (or feature)

[Ng Pheng Siong]

Hi,

I have encountered a problem with proxy roles with my product GuardedFile.

A GuardedFile is a File that is accessible by proxy only. When a GuardedFile
is created, all acquired permissions are unset and a proxy role is created
in its container with the sole permission 'view'. In all other aspects
a GuardedFile behaves like a File.

Typically, the GuardedFile creator next creates a DTML method and assigns
to it the associated proxy role. Anonymous and other users access the 
GuardedFile via the DTML method.


I've discovered a problem with the product setup: Suppose user 'ngps' exists
in the top-level user folder, and has the default roles 'owner' and
'manager'.

1. ngps creates a folder called 'junk' somewhere within Zope. 

2. ngps switches to the folder 'junk'.

3. ngps creates a GuardedFile 'agf'. A proxy role 'proxy_for_agf' is
automatically created in 'junk'.

4. ngps creates a DTML method 'view_agf' to access 'agf'. When ngps tries 
to assign the role 'proxy_for_agf' to 'view_agf', the following error is 
generated: (Slightly reformatted for readability.)

   You are not authorized to change 'view_agf' because you do not 
   have proxy roles.
   
   Traceback (innermost last):
     File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 222, 
        in publish_module
     File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 187, 
        in publish
     File C:\pkg\Zope220b3\lib\python\Zope\__init__.py, line 221, 
        in zpublisher_exception_hook
       (Object: view_agf)
     File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 171, 
        in publish
     File C:\pkg\Zope220b3\lib\python\ZPublisher\mapply.py, line 160, 
        in mapply
        (Object: manage_proxy)
     File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 112, 
        in call_object
       (Object: manage_proxy)
     File C:\pkg\Zope220b3\lib\python\OFS\DTMLMethod.py, line 273, 
        in manage_proxy
       (Object: view_agf)
     File C:\pkg\Zope220b3\lib\python\OFS\DTMLMethod.py, line 266, 
        in _validateProxy
       (Object: view_agf)
   Forbidden: (see above)


The following works around this:

1. ngps creates a user folder in 'junk'.

2. ngps adds a user in 'junk' called 'user2', with roles 'owner',
'manager' and 'proxy_for_agf'.

3. Login as 'user2'; 'user2' is now able to assign the role 'proxy_for_agf'
to the above-mentioned DTML method 'view_agf'.


This proxy role handling seems unwieldy, in that 'ngps' cannot assign
the proxy role but can create another user 'user2' that _can_ assign
said proxy role.

Is this a bug or a feature?


Cheers.
-- 
Ng Pheng Siong <ngps@post1.com> * http://www.post1.com/home/ngps