epoll-shim

This is a small library that implements epoll on top of kqueue. It has been successfully used to port libinput, libevdev, Wayland and more software to FreeBSD: https://www.freshports.org/devel/libepoll-shim/

It may be useful for porting other software that uses epoll as well.

There are some tests inside test/. They should also compile under Linux and can be used to verify proper epoll behavior.

However, this library contains some very ugly hacks and workarounds. For example:

• When using timerfd, signalfd or eventfd, read, write and close are redefined as macros to internal helper functions. This is needed as there is some internal context that has to be free'd properly. This means that you shouldn't create a timerfd/signalfd in one part of a program and close it in a different part where sys/timerfd.h isn't included. The context would leak. Luckily, software such as libinput behaves very nicely and puts all timerfd related code in a single source file.
• There is exactly one static int reserved for fds that can be polled but are not supported by kqueue under FreeBSD. This includes graphics or sound devices under /dev. You can only have one of them throughout all epoll instances in your process!

Installation

Run the following commands to build libepoll-shim:

$ mkdir build
$ cd build
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo
$ cmake --build .

To run the tests:

$ ctest --output-on-failure

To install (as root):

# cmake --build . --target install