I forked this repo from mysqludf/lib_mysqludf_json and made some modifications 👇
I renamed functions json_array & json_object as udf_json_array & udf_json_object, because json_array & json_object have became mysql native functions since version 5.7.8. So if you don't change their name, you can't create udf with the same name as native functions'.
And of course, I changed json_array & json_object udf' names in lib_mysqludf_json.sql.
Original readme file is here
I deleted the old lib_mysqludf_json.so file, not only because it has udf with name like json_array/json_object, but also because it's just a 32-bit version.
So, you can compile it yourself using command gcc $(/your/mysql/bin/path/mysql_config --cflags) -shared -fPIC -o lib_mysqludf_json.so lib_mysqludf_json.c.