One of the things I need for xqdr, the flying robot that I’m building, is a terminal multiplexer, like screen or tmux. I use tmux, personally, and jeepers wouldn’t it be neat to have it run natively on my phone so that I don’t have to use ConnectBot to an outside server and then do “tmux attach”?

Fortunately (or so I thought when starting this project), tmux is written entirely in C. This turned out to be difficult, and so I’ll outline how I did it.

The Android kernel uses a slimmed down version of standard C libraries (libc.so), called bionic. This is where all the allowed calls are stored. It’s possible to either:

Surprisingly, I attempted the second option first. This was insane. I had to compile a compiler to compile a compiler to compile a compiler to compile a shared object library through a perl wrapper to compile the code. I think I made it through all the compiling compilers parts, and then my finished compiler crapped all over its pants.

It was at this point that I decided to check my phone, and I realised that CyanogenMod7 already has a shared object library for standard C. (It’s at /system/lib/libc.so). There is the possibility that I could use this pre-ARM-compiled library, bundle it with tmux, and then use Android NDK to compile tmux for ARM. This would also necessitate creating a .JNI makefile for the frontend, which includes a trivial amount of Java to wrap the native code.

I’ll update when I finish or fuck myself over, but right now I’m getting on brutal series of international flights for Chaos Computer Club‘s 28C3 in Berlin, and my connection is slower than liberal reformist tactics are at creating a freer society.

♥Ⓐ

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