successive chroots thanks to continuations?

[Bauduin Raphael]

Hi again,

I have defined several chrooted environments on my computer.
I'd like to issue the same command(s) in each of them. In a shell
I can do it with a for loop (example chrooting 2 successives times to
the same chroot)

for f in "/mnt/test-chroot/" "/mnt/test-chroot/"; do chroot $f ls -a
/mnt; done

I wondered if I could do it in Ruby using Dir.chroot.
The problem is that this changes the root for the running script,
and getting out of it is not possible (I suppose).
Having just read that continuations saved the whole context when it is
created, I thought to use it, but it doesn't work (script below chroots
correctly the first time, but not the second).

Is what I am trying to do possible?

Thanks.

Raph


#!/usr/bin/ruby1.8
["/mnt/test-chroot","/mnt/test-chroot"].each do |dir|
callcc{|cc|
p "will chroot to "+dir
Dir.chroot(dir)

p "will list files in /mnt for chroot " + dir
Dir.foreach("/mnt") {|f| p f}

p "*"*80
cc.call
}
end

 

[Eric Hodel]

--apg+fY3UKMMABzWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Hi again,
=20
I have defined several chrooted environments on my computer.
I'd like to issue the same command(s) in each of them. In a shell
I can do it with a for loop (example chrooting 2 successives times to
the same chroot)
=20
for f in "/mnt/test-chroot/" "/mnt/test-chroot/"; do chroot $f ls -a=20
/mnt; done
=20
I wondered if I could do it in Ruby using Dir.chroot.
The problem is that this changes the root for the running script,
and getting out of it is not possible (I suppose).
Having just read that continuations saved the whole context when it is
created, I thought to use it, but it doesn't work (script below chroots
correctly the first time, but not the second).
=20
Is what I am trying to do possible?

The command above uses chroot(8) to run the command in a subshell.
Ruby's chroot uses chroot(2) which is permanent. You would have to use
fork get around this.

#!/usr/bin/ruby1.8
["/mnt/test-chroot","/mnt/test-chroot"].each do |dir| fork do
p "will chroot to "+dir
Dir.chroot(dir)
=09
p "will list files in /mnt for chroot " + dir
Dir.foreach("/mnt") {|f| p f}
=09
p "*"*80 end
end

--=20
Eric Hodel - (e-mail address removed) - http://segment7.net
All messages signed with fingerprint:
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--apg+fY3UKMMABzWO--

 

[ts]

B> for f in "/mnt/test-chroot/" "/mnt/test-chroot/"; do chroot $f ls -a
B> /mnt; done

chroot(1) is an user command

B> Having just read that continuations saved the whole context when it is
B> created, I thought to use it, but it doesn't work (script below chroots
B> correctly the first time, but not the second).

What do you call a context ?

I hope that you don't expect that this work

svg% cat b.rb
#!/usr/bin/ruby
["b.rb", "b.rb"].each do |file|
callcc {|cc|
File.unlink(file)
cc.call
}
end

svg%



B> Is what I am trying to do possible?

use Kernel#fork, with Process::wait and Dir::chdir, Dir::chroot


Guy Decoux

 

[Bauduin Raphael]

B> for f in "/mnt/test-chroot/" "/mnt/test-chroot/"; do chroot $f ls -a
B> /mnt; done

chroot(1) is an user command

yes. Take this as what I want to duplicate in "pure" Ruby.

B> Having just read that continuations saved the whole context when it is
B> created, I thought to use it, but it doesn't work (script below chroots
B> correctly the first time, but not the second).

What do you call a context ?

I hope that you don't expect that this work

svg% cat b.rb
#!/usr/bin/ruby
["b.rb", "b.rb"].each do |file|
callcc {|cc|
File.unlink(file)
cc.call
}
end

svg%

hehe, no, I wasn't hoping this would work

B> Is what I am trying to do possible?

use Kernel#fork, with Process::wait and Dir::chdir, Dir::chroot

I'll take a look to those, thanks.

Raph