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RE: Could anyone please explain this to me?

This might work. I will try an easier version first though. Simply
forking twice (thanks again, Peter).

We'll see how it works.


Dr. Michael Meskes, Project-Manager    | topsystem Systemhaus GmbH
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>-----Original Message-----
>From:	joost@rulcmc.leidenuniv.nl [SMTP:joost@rulcmc.leidenuniv.nl]
>Sent:	Sunday, June 29, 1997 4:24 PM
>To:	meskes@topsystem.de
>Cc:	debian-devel@lists.debian.org
>Subject:	Re: Could anyone please explain this to me?
>> I have a binary /foo that essantially does this:
>> cd /
>> fork;
>> if father exit;
>> setsid; 
>> kill all processes not in own session
>> umount /home
>> This works fine, when I simply log in and start /foo as root. However,
>> when I first cd /home after logging in and then start /foo it cannot
>> unmount /home. As you might expect by now, I have to partitions: / and
>> /home. That means I cannot umount /home if I started the binary with cwd
>> on this partition although the child process doesn't even know about the
>> original cwd. And my login shell ahs already been killed.
>> What can I do to avoid this? For my example it's not that big an issue,
>> but imagine /usr being mounted...
>Sue me for being clueless, but:
>  could it be that when you start the programm, you have the
>  current director "open" in some way (like processes can have files open).
>  then, the fork-ed child inherets all open fd's from the parent, and thus
>  also has /home open.
>Maybe (again, just guessing) something like this would help?
>  if (current dir != "/"){
>    cd /
>    execv(myownimage)
>  }
>  kill all processes not in own session
>  unmount /home
>(I'm hoping execv doesn't inherit open filediscriptors. The man page
>doesn't mention anything about this, the execve manpage sais that
>execve does inherit stuff).
>> Thanks in advance
>Well, actuall I don't think this all works, but hey, it could, cound't it?
>joost witteveen, joostje@debian.org
>#!/usr/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj
>$/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1
>#what's this? see http://www.dcs.ex.ac.uk/~aba/rsa/

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