Re: On init in Debian

[Philip Ashmore <contact@philipashmore.com>]

On 16/03/12 21:44, Philip Hands wrote:
> On Fri, 16 Mar 2012 20:05:25 +0100, Andreas Metzler<ametzler@downhill.at.eu.org>  wrote:
> > Philip Hands<phil@hands.com>  wrote:
> > > On Fri, 16 Mar 2012 14:37:39 +0100, Vincent Danjean<vdanjean.ml@free.fr>  wrote:
> > [...]
> > > > * We could try to define a file format that allow a conversion (by a
> > > >    separate specific tool or at runtime) to various init systems.
> > > >    This would avoid to be blocked by the syntax/features of one "source"
> > > >    init system.
> > > This was mentioned in the thread (I forget by whom) and strikes me as
> > > the only viable strategy, in that this is the only way that the various
> > > factions can all collaborate on making a workable solution, rather than
> > > fighting for theirs to be The One True Init.
> > [...]
> >
> > I am not sure this actually is a big improvement, we might end up with
> >
> > * either being limited to the common featureset
> > * or doing something like
> > #ifdef systemd
> > ....
> > elseif upstart
> > ...
> > which is almost as bad as having to ship both init-scripts and systemd
> > configuration file.
> If we were going to end up with anything like that, then it would be no
> improvement at all, and would not be worth wasting any effort on.
>
> I was presuming (perhaps wrongly) that it would be possible to come up
> with a high level specification of what a daemon provides, what it needs
> to happen in order to run, what needs to be done to provoke it to reread
> its settings, how one runs it in the foreground, and in the background
> (either of which might be missing) etc. etc. etc
>
> And then, given that lot, write a generic init.d script that can take
> that as input and do something useful with it, but likewise, process it
> into appropriate configs for both systemd and upstart.
>
> Of course, I don't know enough about either systemd or upstart to know
> how feasible such an approach might be, but if it is feasible it would
> almost certainly eliminate some of the repeated bugs in sysinit at least,
> and perhaps be helpful in the same way for the other two.
>
> On the other hand, the xkcd cartoon is depressingly true, so perhaps we
> should forget that idea -- I was rather hoping that it doesn't quite
> apply here though, since we'd not be trying to write yet another init,
> but just describe the configuration data needed by all init type things.
>
> Cheers, Phil.
I'm writing a system that can accept the following:

    program
    ( name("hello-world")
    , contents
        ( sys-include("stdio.h")
        , function
            ( name("main")
            , returns("int")
            , parameters
                ( parameter(name("argc"), type("int"))
                , parameter(name("argv"), type(array(pointer("char"))))
                )
            , body
                ( call("printf", "Hello, world!\n")
                , return(0)
                )
            )
        )
    )

and parse it into a binary form.

With this I can use a c/c++ generator program to produce

    #include <stdio.h>
    int main(int argc, char *argv[])
    {
        printf("Hello, world!\n");
        return 0;
    }

Would something like this help here?

Regards,
Philip Ashmore