[GSoC Report] Week 5 - Systemd Unit Translator

[K Gopal Krishna <kayg@riseup.net>]

Greetings!

Here are the set of changes in the past week (July 06 - July 12):

  - Added better support for socket files that use a custom service file instead
    of a file with the same name as the socket file.

  - The translator will now work with any supplied path instead of defaulting to
    the current directory. This was done with a bit of `dirname` / `basename`
    magic.

  - Directory creation was changed to be more specific. Directories are now only
    created if they're needed which means that a `xinet.d` directory will not be
    created for a `service` type conversion, etc.

  - Since xinetd is incapable of handling filesystem sockets, socket-activate
    has been used as an alternative. Since there's an obvious feature disparity
    here, additional logic is needed in order to better differentiate and
    delegate tasks between both the tools.

    An overview of how the socket-activate part of the script works:

    - A bash script is created with the used $listenType; first making the
      directory the socket is to be placed in and then pointing to the socket
      itself. Thereafter, the service command is appended to the end.

    - Something worth noting here is that the script does not set `-u` to avoid
      failures due to the service commands referring to undefined variables as
      is the case in `acpid.service`.

    The resulting script is stored in a `socket-activate.d` sub-directory.

  - Instead of having just one big file, the script has been divided into
    smaller scripts that define functions related to a specific unit type. This
    would be beneficial in the future when the translator makes use of
    additional tools.

    - `misc.sh`: Functions which have an all-around usage like create_dirs().
                 This is sourced before the unit type is known.

    - `parser.sh`: Functions responsible for parsing key-value pairs of each
                   unit type. This is sourced before the unit type is known.

    - `{service,socket,timer}.sh` are self-explanatory. These are sourced
      on-demand -- once the unit type is known.

  - Most of the translator is now commented with explanations. Maybe examples of
    using the functions are needed?

Regards,
K Gopal Krishna
(https://kayg.org/)