Instructions for loading an unrestricted python into Battlefield 2142

bf2142_python_upgrade.md

Background

The python interpreter included with vanilla Battlefield 2142 is lacking a fairly large amount of functionality. Much of this involves restrictions on OS interaction, as well as the removal of threading support and the ability to load C extensions. Due to this, a large chunk of the standard library is broken as it depends on functionality that was removed. The goal here is to replace 2142's python interpreter with an unrestricted one and to include the full standard library.

Caveats

• The instructions provided here are for the 64 bit linux server, but the process should work with minor adjustments on 32 bit linux and on windows.
• In Battlefield 2142's custom python interpreter, if an exception is uncaught it will not crash the entire server (like it would in bf2 iirc). Without additional modifications, this process will cause uncaught python exceptions to crash the entire server.
• There is an old blog post about doing this for bf2, but it's very brief and does it in a way that's not entirely correct. This is meant to be a more detailed guide.

Instructions

• First, make a backup of (2142)/bin/amd-64/libdice_py.so. If you end up breaking 2142 in the following process, you'll be able to restore it to a working state from the backup.

Building a new python interpreter

• 2142 uses an ancient version of python (2.3.4). You can grab the source from here: python-2.3.4 download
• Extract it with tar -xf ./Python-2.3.4.tgz and cd into the directory
• Run ./configure --enable-shared BASECFLAGS=-U_FORTIFY_SOURCE and then make
• --enable-shared makes it generate a shared library which we'll need later
• U_FORTIFY_SOURCE is needed because otherwise it crashes during compilation due to a known bug

Replacing 2142's python

• In the compilation directory you'll see a file called libpython2.3.so. Copy this into (2142)/bin/amd-64/ and rename it to libdice_py.so.
• This next part isn't strictly necessary, but centralizes everything and makes it easier to manage.
• Create a new folder in (2142)/ called pylib
• From the compilation directory, copy the contents of ./Lib/ and ./build/lib.linux-x86_64-2.3/ into (2142)/pylib/
• Now you need to point 2142's python to use the new libraries. In (2142)/python/bf2/__init__.py add the following near the top of the file:

  import sys
  sys.path = ['pylib/', 'python/', 'mods/bf2142/python/', 'admin/']

• If you didn't use pylib/, point sys.path at your equivalent.

Adding new python modules

• Now that you've got an unrestricted python set up, you can start using some of the more fun/interesting python modules in your 2142 mods.
• The module that motivated me to go through this process in the first place is ctypes, so I'll show how to set that up here. The process should generalize to whatever other modules you want to set up.
• Download the source from here: ctypes download
• Extract it, etc.
• Run LD_LIBRARY_PATH=/path/to/python-2.3.4-build-dir/ python-2.3.4 setup.py build
• Of course, replace the placeholders with the actual paths to your python comipilation directory and binary
• You can then copy the contents of ./build/lib.linux-x86_64-2.3/ into your (2142)/pylib/ directory
• If you did everything correctly up to this point, you should be able to import and use your module from within 2142's python

If you're wondering how ctypes could be useful, I'll be posting again soon about using it to dynamically add python callbacks for game events that are currently inaccessible to python.

EDIT: adding new python events