The fseek() call has been removed from _Py_FindEnvConfigValue (previously in getpath.c).

There is a single file called ffi.c in the master branch: ./Modules/_ctypes/libffi_osx/ffi.c And this file doesn't call calloc(). I guess that the bug was in our embedded copy of libffi (Modules/_ctypes/libffi/src/arm/ffi has been removed). Copy which has been removed in the meanwhile. If someone cares, check if all calloc() calls are checked for failure in https://sourceware.org/libffi/

From the Python point of view, all bugs described in this issue are now fixed.

Thanks for the report and thanks for the fix ;-)