www.nico.schottelius.org/software/cinit/browse_source/cinit-0.0.5/old/idea02

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/etc/cinit
-> init/
-> shutdown/
-> reboot/
<service>
needs/ -> we wait until all parallel processes are finished _and_ we
don't start if one fails
wants/ -> we start all of them parallel and wait for them?
hold/
wait -> wait until process finished
run -> program to execute
params -> \n seperated argument list
respawn -> respawn it
services may only be under /etc/cinit?
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Service-Status: (see struct svc, cinit.h)
- abs_path
- status (respawn,tmp,once)
- pid
abs_path\0status\0pid\0
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starting services:
run_svc("/etc/cinit/service/")
-> exec run $params
Later:
-> check if service already running -> return OK
-> check needs/ -> check wants/
-> run_svc($cur)
When run_svc returns, the service is started and all service it needs, too.
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-> check needs/
-> exists -> fork( run_run_svcs() ) and continue
(fork) -> fork() run_svc(needs/*);
-> check wants/
-> exists -> run_svc(wants/*);
-> waitfor(need_run_svc)
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run_run_svcs()
-> start parallel (forked) run_svc() for every service
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main()
- run_svc /etc/cinit/init/
- sleep()? -> simply do nothing -> do we need to fork ourselves? No, we are init.
spaeter:
- open /dev/console W_ONLY
- make stdin == /etc/cinit/in
- make stdout, stderr /dev/console
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eof
Things, which are clear
- we need to fork before execl(), as excel() replaces us.
- chdir() _after_ fork()
profiles support: profile=$profile
start
"service.$profile" if exists, instead of
"service"
starting services:
cinit:
pipe()
set_status_tmp()
fork() --> failure --> clear_service
cinit_process_watcher():
fork()
execve(process,args,env)
waitpid() -> for once? PROCESS MUST RETURN!
write_pipe()
rmpipe()
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What to send over to cinit and read back?
- first you need two pipes for every process: read+write (on both sides)
- cinit wants
o command
- service temporary - trying to start in right now.
- service executed once - fine
- service executed once and that failed - :-(
- service respawing
o an identifier for the service (i from service list ;-)
--> makes 2 bytes to read
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How cinit works:
cinit says: I want to start service xyz. (/etc/cinit/init on bootup)
cinit calls run_svc().
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int run_svc(char *relative_path):
- check if service is already running or temporary (task list!)
-> yes: return RT_PAR_OK
-> no: continue.
- set service to be temporary (ST_TMP) and retrieve SID (service ID)
- walk through dependency tree and call run_svc
- fork() -> so cinit can continue.
- write cinit: check service, I want to start it
-> returns status of service (see ST_* in cinit.h)
- cinit returns: ok, you are temporary
- [that checked] check if service
o is already started
o is beeing started
x check if rpath S_ISDIR
x chdir(dir)
- check needs - check wants
- for every needs/* start run_svc
- check respawn -> respawn = true
- check run
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add_mod_svc(char *svc, int status)
-> add or modify status of a service
- check whether service exists, reset status
- if not exists, insert if maximum of services is not reached
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cinit communications proto
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cinit:
-> signal_handler on SIGCHLD
run_init()
-> run_svc(init)
-> fork() -> do the work
signal_handler_child
waitpid(.*)
-> returns pid
oder waitpid() in dem run_svc, wenn need/once?
need:
for i in need/*; do
( $service & );
done
wait(.*);
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cinit:
run_svc:
checks what it needs (need/*)
need/*
fork()
fork(), fork()
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Kommunikationsproblem:
-> 1024 ist maximale anzahl offener sockets -> 510 von fifos,pipes
- mehrere FIFOs?
--> kommunikation gesichert, extrem viele fifos...
--> etwas unsauber, aber geregelte kommunikation
- mehrere PIPEs?
--> viele PIPEs (HRHR)
--> programme koennen nur von cinit gefork()ed werden.
--> eine datei mit prozessen?
--> einen RAM Bereich?
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cinit[1] <-> fifo <-> forker
forker?
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pfad vorher aufloesen?
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Kommunikation: ::Test::
Test mit nur 2 FIFOs!
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sig_fifo()
read(..) als hauptaufgabe?