Leosac is an open source physical access control system software. It is meant to be installed on embedded devices running Linux, to handle the logic processing of an access control. Basically, it opens doors.
A Leosac setup is usually composed of an embedded Linux board running the software, locked in a case, connected to a RFID card reader and to the electric strike of a door.
The documentation for both end-user and developpers can be found at http://islog.github.io/leosac/doc_output/develop/html/