Consider the following scenario:
A python tool should be deployed for external users in a way that (a) the source is protected and (b) it is ensured that only users with valid license can use it. Furthermore, for internal users, the code should be available as pure python, so debugging with a python debugger is possible and no compiling is necessary.
A license check is available and written in C.
(a) is solved by using cython.
Thoughts on (b):
The license check could be applied to a "central" part of the program (i.e., "a class that contains enough business logic so that no one could replace it"). Of course I could use cython to link the license check to this class's *.pyd and use the c function, but then it would be impossible for the internal user to use / debug the class. On the other hand, applying the license check to a class that is "unimportant" while debugging would mean that it could (presumably) be exchanged rather easily.
Creating a separate function "licenseIsValid() -> bool" and calling it from a central position in the code is not feasible as it can be replaced easily.
As a matter of fact, (almost) everything written in python can be replaced and therefore is unsafe.
So I came up with the idea of implementing the license check before anything python-related is executed: inside of the dllmain function. I could call the license check function on startup of the dll / pyd and stop the application before executing any cython code.
Is there a way to add a custom dllmain to a cythonized module? Is it even safe to add a dllmain (or does cython require a "specialized" dllmain)?
One last remark: I am aware that python is the wrong choice of language for creating closed source code with license check. But the advantages of using python far outweigh this...
Thank you in advance, Jan