Python 2 to Python 3 .so library incompatibility - need help

[Chris Angelico]

On Thu, Dec 17, 2020 at 7:27 AM MRAB <python at mrabarnett.plus.com> wrote:
>
> On 2020-12-16 19:16, Chris Angelico wrote:
> > On Thu, Dec 17, 2020 at 6:06 AM Chris Green <cl at isbd.net> wrote:
> >>
> >> Some time ago (in July) I asked some questions here
> >> about problems migrating some code from Python 2 to Python 3.
> >>
> >> The specific problem that finally prevented me from managing to get it
> >> to work was a (Linux) .so file that had been built for Python 2 and,
> >> as I don't have the source, I can't build for Python 3.
> >>
> >> I need to have another go at fixing this as otherwise the code that I
> >> need to manage my printer will stop working as I update my Ubuntu
> >> systems.
> >>
> >> The specific error I'm getting is as follows:-
> >>
> >>     File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
> >>     ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct
> >>
> >> I know this is because the extension module is compiled for Python 2
> >> and _Py_ZeroStruct is only available in Python 2.  I don't have the C
> >> code for the module.
> >>
> >> Is there *any* other way around this, like a 'compatibility module' to
> >> use Python 2 .so files in Python 3 or anything like it?  I have all
> >> the Python code and have (up to hitting this problem) converted it to
> >> Python 3.
> >>
> >
> > Basically no. The error you're seeing is a nice noisy one, but even if
> > you got past that, there'll be a LOT of incompatibilities.
> > Unfortunately, a quick google search for 'pyscand' showed up....
> > places where you've asked this question, suggesting that nobody else
> > uses this library. It looks like you're going to have to take a big
> > step back and figure out what the library is doing for you, and
> > reimplement that somehow. :(
> >
> > Good luck.
> >
> Alternatively, run something in Python 2.7 that can import it and talk
> to the main Python 3 code, at least until you have a long-term solution.

Yes, that's a possibility. A hack, but a definite hack. But this is
one of the places where the universality of stdin/stdout is extremely
handy.

ChrisA