Liblazy - D-Bus methods provided for convenience

[Holger Macht]

[If that's not the right way for a hosting request, please direct me to
the right place]

Hi,

Once in a while, I stumble across an application which has no proper D-Bus
support and gathers some information through reading /proc or sysfs, or
any other circumstantial way, although software like HAL or PolicyKit
already have this information. Or they just want to send a simple message
to another application, sometimes even without caring about the reply.
These applications often only have to do very simple tasks.

So to adopt these applications, I always have to duplicate lots of code
over and over again.

Just some examples...

I have to send a message over D-Bus I have to do:
  1. Get a D-Bus connection
  2. Check for errors
  3. Send a message over the bus
  4. Check for errors
  5. Get the reply
  6. Check for errors

I have to get a simple property from HAL, I have to do (with libhal in
this example):
  1. Get a D-Bus connection
  2. Check for errors
  3. Get a LibHalContext
  4. C.f.e.
  5. Register the connection with the context
  6. C.f.e.
  7. Fetch the property with libhal
  8. C.f.e 

When I have to check if I possess a specific privilege according to PolicyKit:
  - Either do a mixture of the above things to ask directly via D-Bus or
    link against libpolkit and do a complicated call of
    libpolkit_is_uid_allowed_for_privilege(7 arguments follow). This call
    gives you a lot of information you might not care about at all.

So in every application, I implemented functions like:

   dbus_send_message(service, path, interface, method);
   dbus_send_message_with_reply(service, path, interface, method, &reply);
   hal_get_property_int(udi, property)
   ...

There are a lot of applications which just don't want to care too much
about D-Bus or HAL at all. I'm talking about small applications, of
course, even about those without a mainloop. They just want to make use of
hardware databases and abstractions and a new way of inter process
communication we have with D-Bus these days.

So what I've done and still doing is combining these very simple functions
into one small library called liblazy. A small application may just want
to do the following to send a message over the bus and get its reply,
maybe even with ignoring any errors:

  DBusMessage *reply;
  liblazy_dbus_system_send_method_call("org.freedesktop.NetworkworkManager",
                                "/org/freedesktop/NetworkManager",
                                "org.freedesktop.NetworkManager",
                                "sleep",
                                &reply,
                                DBUS_TYPE_INVALID);

  int *arg_from_reply;
  liblazy_dbus_message_get_arg(reply, DBUS_TYPE_INT32, &arg_from_reply, 0);

That's it. The application developer just has to link against libdbus and
liblazy, without caring about any other stuff.

Liblazy also contains very simple functions to get a property from HAL or
ask for a privilege from PolicyKit. But it doesn't contain complex
functionality. It may grow as needed, though. But...

It is definitely not intended for replacing any of the dbus bindings,
libhal or libpolkit. Complex applications can and will still have their
own implementations and will link agains libhal or libpolkit or
whatever. Liblazy is intended for small applications which only need a
subset of functionality and like to profit from new software like D-Bus,
HAL, etc. but without having to care a lot. It should serve as a set of
functions for developers provided for convenience. Also a lot more command
line applications could make use of HAL, etc. in an easy way IMO.

So the purpose of this mail is actually that I'm looking for a place to
host it. And freedesktop.org was the first logical choice, because it
already hosts a lot of software (D-Bus, HAL, etc.) liblazy cares
about. And liblazy definitely is cross desktop oriented.

So what about getting a git repository for it?

Thanks in advance,
       Holger