xorg input driver

Question

I need to write a xinput driver for a virtual device, e.g. http://cgit.freedesktop.org/~whot/xf86-input-random. The device is connected to a LAN. The client for this device is written in C++. Is it possible to use C++ code in this driver or must the whole project be C only?

Answer 1

An Xorg driver is just an ELF shared object plugin following some documented convention. In principle, how you obtain that .so is your own business (you could in theory write it manually bit by bit if you have centuries of your time to lose). In principle, you could link the libstdc++.so to your shared object (since one can link shared objects to other ones). I guess that you would compile and link your plugin with g++ and perhaps explicitly need to link with -lstdc++

However, I guess that it might be unsafe. Perhaps C++ ABI requires some specific things to be executed by the crt0.

So you might try, but I won't be surprised if something does not work as you want (e.g. exception handling). It could depend upon the version of the C++ library and the version of the C library and the version of the compiler.... I guess that it might work better with recent g++, recent libc, recent libstdc++ ....

Read Drupper's paper: How to Write Shared Libraries

Make your driver free software, and publish very quickly its source code, so you could get some help from the Xorg community (even when your driver is incomplete). Use probably a recent Xorg....