www.nico.schottelius.org/software/cinit/browse_source/cinit-0.3pre5/doc/devel/cinit-0.4.text
Nico Schottelius 423ba10303 import cinit from unix.schottelius.org
Signed-off-by: Nico Schottelius <nico@ikn.schottelius.org>
2009-09-16 12:53:45 +02:00

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cinit 0.4 - Redesign of cinit
============================================
Nico Schottelius <nico-linux-cinit__@__schottelius.org>
0.4.0, for cinit 0.4, Initial Version from 2006-03-11
:Author Initials: NS
cinit 0.2 ran fine and the general project of developing a
parallel executing init system is finished.
With cinit 0.4 there are new aims to reach.
Introduction
------------
. AIMS
- portability: no Linux-dependency anymore
- cleaner signal handling
- better documentation so more people can use it
Current problems
----------------
Temporary filesystem and socket problematic
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The mount(2) system call is os-specific.
The temporary fs is os-specific.
Signal handlers are not clean
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Race conditions when multiple signals arrive
Reboot code is os specific
~~~~~~~~~~~~~~~~~~~~~~~~~~
serv/sig_reboot.c contains umount, remount hard coded.
Solutions
---------
Temporary filesystem and socket problematic
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Remove
- the mount call
- do not create an initial socket
Wait until we recieve a signal, then we create a socket
under the configured socket directory (see `conf/sockdir`).
Signal handlers are not clean
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Reboot code is os specific
~~~~~~~~~~~~~~~~~~~~~~~~~~
Misc
~~~~
- Configuration
/etc/cinit/config/
init -> link to initial service
pre_boot
pre_boot_args
post_boot
post_boot_args
/etc/cinit/services/
/etc/cinit/profiles/
links to the starting services
cinit - Internals
=================
Nico Schottelius <nico-cinit__@__schottelius.org>
0.1 for cinit-0.3, Initial version: So Feb 19 10:25:46 CET 2006
:Author Initials: NS
Introduction
------------
This document describes the internals of cinit. It is thought
to be read by developers.
Child handler code in cinit-0.3
-------------------------------
In cinit versions <= cinit-0.2.1 the respawning services where
handled by an extra child handler, which was a fork of cinit. This
had some problems:
- We allocated more memory than necessary, unecessary parts of
cinit were copied
- The SIG_CHILD-handler was not written very clean, in some versions
it was completly missing.
. So in `cinit-0.3` we changed it the following way:
- no extra child handlers
- handle everything in the SIG_CHILD handling function
- when sig_child is recieved do:
- check against respawn list
- if it is a respawning service, [do the following in a seperate fork?]
check whether it successfully stoped
- if yes: restart immediatly
- if no: sleep $sleep_time and then restart