BLT4L Readme

BLT4L is a part clean-room, part-line-by-line rewrite of BLT, the PAYDAY 2 Better Lua injecTor, for Linux. It is compatibile with all BLT mods, presents the same API, and uses the same LUA base.

Credits

• Roman Hargrave - Initial work, code, translations from BLT4WIN
• Leonard König - C++ cleanup, linker work
• Ozymandias117 - Fixed subhook on 64-bit platforms
• James Wilkinson - BLT LUA (and BLT)

Installing

You can install BLT4L in a few different ways. The quickest way is to clone this repository, and run install.sh. This will work best on Debian, or a Debian derivative, such as SteamOS, as it can help you install missing dependecies.

If you're on Arch Linux (or a derivative like Manjaro), you can install the AUR package blt4l-runtime-bin (Steam runtime) or blt4l (non-Steam runtime/steam native). You'll still need to install the base Lua manually, see the instructions below for a manual install.

You can also find prebuilt copies under the releases tab, or if you want to debug or modify BLT4L, you can build it manually.

Building & Manual Install

In order to build BLT4L, you will need:

• openssl
• curl4-openssl (gnutls is NOT supported)
• zlib
• cmake
• a build tool chain (most distros have one preinstalled, or available in a build-essentials package)

Do the following:

$ git submodule init
$ git submodule update
$ mkdir build 
$ cd build
$ cmake .. 
$ make

You should find the hook in your build folder, named libblt_loader.so. You will need to set LD_PRELOAD for the PAYDAY2 process to find the loader.

Next, you will need to copy a LUA mod base to your PAYDAY 2 folder (or whatever working directory you intend to run PAYDAY 2 in). There is a symlink to the BLT LUA mod base (from the BLT4WIN submodule) under lua/mods.

If you set everyting up correctly, you should be up and running with the BLT mod API in PAYDAY 2.

Additional work for SELinux users (e.g. Fedora users):

Because our hook writes to executable sections of payday2, SELinux doesn't like us (and it shouldn't). In order to add an SELinux exception for the BLT Hook, you must do the following:

Run Payday2 with libblt_loader.so (It will crash, and SELinux will log the error)

$ sudo ausearch -c 'payday2_release' --raw | audit2allow -M my-payday2-hook
$ sudo semodule -i my-payday-hook.pp

Notes

I am a bit out of my element writing C++, as I prefer to use C; however, it is more convenient to use C++ when you're trying to call and overwrite functions in a C++ application. For this reason you may notice a few C-like things in the C++ code. Feel free to correct them and open a PR.

Additionally, I should point out that I am using the linker to access the lua_* functions. This is because (as of 2016-03-22) the payday2_release image is not stripped (or at least not fully; as is sometimes the case with staticly linked images). For this reason we can forego signature hunting and the like, as we have symbols and the linker, the ultimate signature system. I've backed up a copy of the payday image should a stripped update come out and necessitate signatures.