interfaces/python: remove use of deprecated method '_Py_fopen_obj'

[lrusak]

this fixes the following warning:

xbmc/interfaces/python/PythonInvoker.cpp:310:31: warning: ‘FILE* _Py_fopen_obj(PyObject*, const char*)’ is deprecated [-Wdeprecated-declarations]
310 | FILE* fp = _Py_fopen_obj(pyRealFilename, rb);
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
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• My code follows the Code Guidelines of this project
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• I have updated the documentation accordingly
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• All new and existing tests passed

[github-actions]

Critical

Incorrect function signature (xbmc/interfaces/python/PythonInvoker.cpp:310)
The replacement function Py_fopen has a different signature than _Py_fopen_obj:

• _Py_fopen_obj(PyObject* path, const char* mode) - takes PyObject* for path
• Py_fopen(const char* pathname, const char* mode) - takes const char* for path

The code passes pyRealFilename (PyObject*) to Py_fopen which expects const char*. This causes undefined behavior.

Suggested fix:
(1) Use realFilename.c_str() directly: FILE* fp = Py_fopen(realFilename.c_str(), "rb");
(2) Remove the now-unnecessary pyRealFilename PyObject creation and DECREF
(3) This also simplifies the code since the PyObject wrapper is no longer needed

[bkuhls]

A different fix for the problem is included in #27391

[sundermann]

Isn't Py_fopen only available from 3.14+? https://docs.python.org/3/c-api/sys.html#c.Py_fopen. But as mentioned the fix is already in #27391 but could be cherry picked from there

[lrusak]

Isn't Py_fopen only available from 3.14+? https://docs.python.org/3/c-api/sys.html#c.Py_fopen. But as mentioned the fix is already in #27391 but could be cherry picked from there

Yep, I missed that.

No worries. I only noticed because fedora 43 ships with python 3.14

$ rpm -qa | grep -E 'python3-[0-9].*' 

python3-3.14.0-2.fc43.x86_64

So it's probably worth getting that fix for the warning in. I can just cherry-pick your commit if desired.

[sundermann]

Sure, just cherry pick the commit from my PR, saves me one rebase

[lrusak]

Sure, just cherry pick the commit from my PR, saves me one rebase

Done, I just updated the commit message a little bit.