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