Move example configuration files to examples subdirectory

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Add basic support for dynamically loadable plugins

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Refactor main() into more functions and convert #ifdef hell into plugins.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Convert finit to use libev and fix so plugin ctors runs on dlopen().

Lots of cleanup and simplification of the main code in this commit.
Most notably libev has been added to take care of the main loop and
monitor services. Still TODO is migrating to use the libev signal
handling.

Convert initctl.c:listen_initctl() to a plugin instead.  This also
meant introducing a new form of I/O plugin to finit, also handled
by libev.

Load plugins *after* we've setup the base filesystem (BASEFS) in case
plugins reside on a filesystem not reachable before "mount -a" has run.
This also has the side effect of lining up nicely with the first level
plugin hooks.

If a plugin wants to hook up with a loded service we connect them by
their respective numeric IDs in plugin_register().  I.e., the service
monitor checks if a service has a registered callback, which in turn
decides if a service should be started, stopped or reloaded.

Rip out old EeePC distribution defines from finit.h, none of it really
applies anymore.  If you need distribution specific settings this is
the place to put them.

Make hookpoint names (#defines) clearer: after BASEFS, after networking,
after all setup, etc.

Use #inlude_next <signal.h> in signal.h to include system header file!

Simplify service monitor: move essential code to svc.c and rip out
the TIPC dependency. Write your own service.so plugin, or wait for
a more complete example of how to extend service monitoring using
the primitives in svc.c

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Refactor conf-file parser into a file of its own.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Move fork() of console to run_getty() and remove startx conf option

New function helpers.c:run_getty() refactored from main(). Used to
start a default console getty.

Removed startx finit.conf option, superseded by service statement,
see examples/finit.conf for a working use case.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Revert new experimental libev backend due to time constraints

Due to time constraints I had to revert the new libev backend to the
service, I/O and signals monitor.  Employed instead is the tried and
tested signals based service monitor, with a small extension for an
additional I/O monitor using poll() for the I/O plugins to use.

Tried restoring the startx finit.conf directive on top of the service
implementation. However, it's currently not usable to run /usr/bin/startx
for any other user than root. I recommend using the examples/finit.conf
and run /usr/sbin/gdm instead.

finit.c:
        New run_loop() function, replaces libev ev_run().

helpers.c:
        Refactor start_process() into svc_start().

plugin.c:
        Add fds[] array for use in the io_monitor() called by the
        new run_loop().

signal.c:
        Ignore SIGCHLD. Handled by waitpid() in svc_monitor() now,
        which is called by the new run_loop().

svc.c:
        svc_register(): Optional @username parsing for the command line.
        svc_monitor(): Replaced libev callback with waitpid()
        svc_start(): Refactored to use most of helpers.c:start_process()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>