Dongle game

From Easyneufenglish

[edit] Introduction

As part of the EasyNeuf project, we want to make extension keys (dongle) embarking appliactions to extend gate functionalities.

This is a commercial approach and the following constraints must be respected :

• system integration
• auto-countenance
• upward compatibility
• Ease of use
• Update possible

[edit] System integration

[edit] Principle

The main idea is to put a easykey.cfg (this file can be renamed) file in the dongle filesystem root, this file will allows :

• to consider the key as an extension key and then to do a further processing like changing the key icon on the desktop ;
• to specify all the parameters relating to the dongle.

The system integration is mainly done by minihal and the used environment. Two cases are possible:

• either minihal daemon recognize the presence of this index file and then send a signal specific to the environment (easy3d or minidesk) by a UNIX socket

• either the environment, which receive a generic device mounting event by minihal detect the presence of the index file and then perform the specific treatment (change icon, autostart, etc...)

[edit] Index file example

A simple system of keys/values is preferred. The idea is to seperate the different applications to facilitating the update can be found on this file structure:

[easykey]
id = games1
name[fr] = Games extension
icon = games.svg
version = 1

[application1]
id = tremulous
file = applications/tremulous.desktop
version = 1

[application2]
...

.desktop files will be used to integrate the software to the system. Notably, we can modify 9panel and add one more argument to find the .desktop files in the directory of the USB key.

[edit] MIME managment

No need for games but for future applications, the /usr/bin/mime-handle program will take into account the .desktop files of the key and if possible remember to ask the user to insert the key if it is not present.

[edit] Auto-countenance

Dongles have to be doivent être auto-containers and must not use system ressources. So we propose that all applications of a dongle have to be executed in an auto-contained chroot. To allow system integration of backup and highscores or configuration files, we propose to mount the directory */home/$USER* and the directory */var/games* (for example) containing gate global hi-scores or others...

[edit] Key organisation

We propose the following organisation for each dongle:

o--+--  easykey.cfg
   |
   +--  icons/
   |
   +--+ applications/
   |  |
   |  +--  *.desktop
   |
   +--+ system/
   |  |
   |  +--  lib/
   |  |
   |  +--  bin/
   |
   +--+ components/
      |
      +--+ tremulous/
      |  |
      |  +-- bin/ 
      |  |
      |  +-- usr/share/...
      |  |
      |  +-- ...
      |
      +--+ wesnoth/
         |
         +-- bin/ 
         |
         +-- usr/share/...
         |
         +-- ...
       

[edit] Program execution

Execution of each application will be done by invocate a script placed on the *system*. So it will be necessary to have an updated gate to execute applications from the dongle (the update must be planned before the dongle commercialisation). Execution configuration for each application will be done by .desktop files present on the dongle.

Example of .desktop fiule

[application]
id=tremulous
name=Tremulous
program=/bin/tremulous
description[fr]=Fight game between marines and aliens

Then, we will use a script nearly like this one (disclaimer: not tested yet) on which we will put the .desktop file as an argument. For example: /usr/bin/run-app.sh /path/to/dongle/applications/tremulous.desktop.

#!/bin/sh

application_program=`grep -i '^Exec=' $1 | sed -e 's/^.*= *//g'`
application_id=`grep -i '^id=' $1 | sed -e 's/^.*= *//g'`

mount --bind /home/$USER /path/to/dongle/home/$USER
mount --bind /path/to/dongle/$application_id /path/to/dongle/system/$application_id

chroot /path/to/dongle/system $application_program

[...] # Verifying that the program is well executed

umount /path/to/dongle/home/$USER
umount /path/to/dongle/system/$application_id

[edit] Possible update

The idea is to have a dongle update utility directly in the gate which one will be executed manually by the user. Idealy, we download a set of .tar files, we uncompress it in the directories of key components.

[edit] Sécurité

Openssl signature (a certificate must be present on the system for verification). This certificate will have a long lifetime to allow a rotation by updating the gate on the day it expires.