Creating Import Hooks

Sreejith K sreejithemk at gmail.com
Thu Feb 18 13:15:43 CET 2010


On Feb 18, 3:49 pm, Jean-Michel Pichavant <jeanmic... at sequans.com>
wrote:
> Sreejith K wrote:
> > On Feb 18, 1:57 pm, Steven D'Aprano
> > <ste... at REMOVE.THIS.cybersource.com.au> wrote:
>
> >> On Thu, 18 Feb 2010 00:03:51 -0800, Jonathan Gardner wrote:
>
> >>> On Feb 17, 10:48 pm, Sreejith K <sreejith... at gmail.com> wrote:
>
> >>>> Hi everyone,
>
> >>>> I need to implement custom import hooks for an application
> >>>> (http://www.python.org/dev/peps/pep-0302/). I want to restrict an
> >>>> application to import certain modules (say socket module). Google app
> >>>> engine is using a module hook to do this (HardenedModulesHook in
> >>>> google/ appengine/tools/dev_appserver.py). But I want to allow that
> >>>> application to use an sdk module (custom) which imports and uses socket
> >>>> module. But the module hook restricts the access by sdk. Finding out,
> >>>> which file is importing a module give a solution?? ie. If the
> >>>> application is importing socket module, I want to restrict it. But if
> >>>> the sdk module is importing socket I want to allow it. Is there any way
> >>>> I can do this ?
>
> >>>> Application
> >>>> ========
> >>>> import sdk
> >>>> import socket               # I dont want to allow this (need to raise
> >>>> ImportError)
>
> >>>> SDK
> >>>> ====
> >>>> import socket               # need to allow this
>
> >>> SDK
> >>> ===
> >>> import socket
>
> >>> App
> >>> ===
> >>> import SDK
> >>> import sys
> >>> socket = sys.modules['socket']
>
> >> I'm not sure, but I think Sreejith wants to prohibit imports from the App
> >> layer while allowing them from the SDK layer, not work around a
> >> prohibition in the SDK layer.
>
> >> In other words, he wants the import hook to do something like this:
>
> >> if module is socket and the caller is not SKD:
> >>     prohibit
> >> else
> >>     allow
>
> >> I could be wrong of course.
>
> >> --
> >> Steven
>
> > @Steven, Thats exactly what I want.. Anyway to do that ??
>
> import sys
> sys.modules['socket'] = None
>
> import socket
> ---------------------------------------------------------------------------
> ImportError                               Traceback (most recent call last)
>
> ImportError: No module named socket
>
> JM

@Jean. Thanks for the reply. But this is not what I wanted. The import
hook already restricts socket imports in applications. But I want them
in sdk package (alone) which is being imported in the application. I
don't want applications to directly use the socket module. That means
I want to make some exceptions for sdk in import hooks.



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