Move documentation to doc/ sub-directory, all except README

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

doc/TODO.md

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+Goals of Finit
+==============
+
+The intent of finit is to monitor not just processes, but to supervise
+an entire system and the behavior of certain processes that declare
+themselves to be finit compliant.  Similar to launchd, the goal of
+finit is to be a replacement for:
+
+* init
+* inetd
+* crond
+* watchdogd
+
+A small and simple replacement, primarily for embedded systems, with a
+low dependency on external packages.  A compliant software is one that
+can run as a damon in the foreground.  If it can also touch its PID file
+after a reconfiguration (`initctl reload`), the Finit dependency system
+can also be used.
+
+
+General
+-------
+
+* Remove shm, let `initctl` call `api.c` for each `svc_t` instead of
+  opening up the inner parts of PID 1 to other processes.  Also, this
+  would prevent issues like #81 from happening.
+* Add support for timed shutdown in Finit, including cancelled shutdown.
+* SysV init and systemd use SIGUSR1 to restart their FIFO/D-Bus.  Add
+  API restart to SIGHUP callback for the same functionality in Finit.
+* Add `finit.conf` support for UPS notification (SIGPWR) to start a task
+  using, e.g. <sys/power/{ok,fail,low}> conditions.  More info in sig.c
+* Add `finit.conf` support for ctrl-alt-delete (SIGINT) and kbrequest,
+  i.e. KeyboardSignal, (SIGWINCH) behavior.  Using conditions to a task,
+  e.g, <sys/key/ctrlaltdel> and <sys/key/signal> like SIGPWR handling.
+* Add `IFF_RUNNING` support to netlink plugin along `IFF_UP`
+* Allow scripts, instead of C code, as process callbacks
+* Add support for a pipe/popen where we can listen for `STOP`, `START`
+  and `RELOAD` on `STDOUT` from a script ... call it for example
+  `.monitor=` in `svc_t` ... the script named as the basename of the
+  service it monitors + `.sh`.
+* Implement `initctl stop|start|restart|reload|status <SVC>` and
+  `service <SVC> stop|start|restart|reload|status` on top
+* Add support for JSON output, or similar, from `initctl show`, e.g.
+  `initctl show --json`
+* Improve `initctl show SVC` output.  Add service uptime, last ten SVC
+  logs/history (historian), etc. Similar to `systemctl show SVC`
+* [Solaris SMF][] (Service Management Facility) has some interesting
+  features that may be well worth looking into adopting:
+  
+         svcs enable -rt svc:/network/ssh:default
+  
+  That is: (r)esolve dependencies and only enable ssh (t)emporary
+  in the default runlevel when networking is available.
+* `initctl add /sbin/service -n -- Service description`, for details
+  see above [Solaris SMF][] featuer, issue #55 and issue #69,
+  https://github.com/troglobit/finit/issues/69#issuecomment-287907610
+
+
+Init
+----
+
+Finit in itself is not SysV Init compatible, it doesn't use `/etc/rc.d`
+and `/etc/inet.d` scripts to boot the system.  However, a plausible way
+to achieve compatibility would be to add a plugin to finit which reads
+`/etc/inittab` to be able to start standard Linux systems.
+
+
+Inetd
+-----
+
+* Add support for throttling connections.
+* Optimize interface filtering by using socket filter.  The functions
+  `inet_*_peek()` and `inetd_is_allowed()` used for interace filtering
+  should be possible to rewrite as socket filters.
+* Optimize HTTP/HTTPS inetd connections by adding basic support for the
+  `inetd` variant `redir http/tcp@eth0 nowait [2345] 127.0.0.1:8080`,
+  which would reduce the overhead of spawn the web server on each HTTP
+  connection, yet still provide a means of filtering access per iface.
+
+
+Crond
+-----
+
+Requirements are quite rudimentary, basic cron functionality, mainly
+system-level timed periodic tasks:
+
+* Periodically run a task, in a matching runlevel
+* Optionally run as non-root (`crontab -e` as operator)
+
+Proposed syntax:
+
+    # Crontab
+    cron @YY-mm-ddTHH:MM [LVLS] /path/to/cmd [ARGS] -- Optional descr
+    
+    # One-shot 'at' command
+    at @YY-mm-ddTHH:MM [LVLS] /path/to/cmd [ARGS] -- Optional descr
+
+Notice the ISO date in notation.  The runlevels is extra filtering
+sugar.  E.g., if cron service is only allowed in runlevels two or three
+it will not start if system currently is in runlevel four.
+
+To run a command as another user the `.conf` file must have a that
+owner.  E.g., `/etc/finit.d/extra.conf` may be owned by operator and
+only hold `cron ...` lines.
+
+What would be extremely useful is if `initctl`, or a homegrown `at`,
+could support the basic functionality of the `at` command directly from
+the shell -- that way setting up one-time jobs would not entail
+re-reading `/etc/finit.conf`
+
+
+Documentation
+-------------
+
+* Write man pages for finit and `finit.conf`, steal from the excellent
+  `pimd` man pages ...
+* Add simple, *very* simple, `finit-simple.conf` example. To illustrate
+  how close Finit3 still is to the original easy-to-use Finit0 :)
+
+
+[libwdt]: http://www.wehavemorefun.de/fritzbox/Libwdt.so
+[Fritz!Box source dump]: ftp://ftp.avm.de/fritz.box/fritzbox.fon_wlan_7170/x_misc/opensrc/
+[Solaris SMF]: http://www.oracle.com/technetwork/articles/servers-storage-admin/intro-smf-basics-s11-1729181.html
+
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