No functional changes.

Signed-off-by: Roman Penyaev <[email protected]>

tio is a simple TTY terminal, which will be used by EVE
for attaching to the application consoles in following
patches. Stay tuned.

Signed-off-by: Roman Penyaev <[email protected]>

Add `tio` and `socat` utilities for the debug service EVE container.
These tools will be used for application console attach.

Signed-off-by: Roman Penyaev <[email protected]>

…commands

The `list-app-consoles` command returns all running QEMU (KVM) consoles in the
following format:

  # /persist/eve list-app-consoles
  PID     APP-UUID                                CONS-TYPE       CONS-ID
  ---     --------                                ---------       ---------
  3883    e4e2f56d-b833-4562-a86f-be654d6387ba    VM              e4e2f56d-b833-4562-a86f-be654d6387ba.1.1/cons
  4072    f6d348cc-9c31-4f8b-8c4f-a4aae4590b97    CONTAINER       f6d348cc-9c31-4f8b-8c4f-a4aae4590b97.1.2/cons
  4072    f6d348cc-9c31-4f8b-8c4f-a4aae4590b97    VM              f6d348cc-9c31-4f8b-8c4f-a4aae4590b97.1.2/prime-cons

The `attach-app-console` command uses a console ID from the `list-app-consoles` as a parameter:

  # eve attach-app-console e4e2f56d-b833-4562-a86f-be654d6387ba.1.1/cons
  [20:26:15.116] tio v1.37
  [20:26:15.116] Press ctrl-t q to quit
  [20:26:15.116] Connected
  <PRESS ENTER>

  Ubuntu 18.04.6 LTS user hvc0

  user login:

The `attach-app-console` command attaches to the virtual QEMU console and pumps
bytes between socket and PTY, so that `tio` terminal can attach to the corresponding
PTY. This gives a fully working terminal of the guest.

Since `socat` and `tio` utilities exist only in the debug service EVE container,
the only way to use `attach-app-console` is to do the `eve enter debug` prior
the console attach. This is done by the `eve` script.

Signed-off-by: Roman Penyaev <[email protected]>

This console is called a 'prime-cons' (could not think a better name)
and will connect the hosting Vm of a container with EVE environment.

So for a container there will be two virtual consoles: 'cons' and
'prime-cons'. The 'cons' is attached to the input and output of the
entry process of a container (this functionality exists for ages),
but a new 'prime-cons' is attached to the input and output of the
getty process of the hosting Vm.

The 'prime-cons' gives a way to execute commands on Vm of a
container.

Signed-off-by: Roman Penyaev <[email protected]>

Start `agetty` in loop on the '/dev/hvc1' virtual console (the other
end of this console is a 'prime-cons' visible on the EVE).

Since by default init process does not have any SID set (is 0), agetty
fails to set control terminal, so job control does not work. In order
to overcome this problem 'agetty' is called by the 'setsid' command,
which creates a SID.

Signed-off-by: Roman Penyaev <[email protected]>

There is no need to do chroot for the parent process before actual
clone is called, all the environment preparation should be as close
as possible to the actual execvp().

The other motivation for this change is the next patch, where PID
file of the child process will be created on the host, but not
in the chrooted container environment. So postpone chroot and move
it to the child process.

Signed-off-by: Roman Penyaev <[email protected]>

Also code tweaks.

Signed-off-by: Roman Penyaev <[email protected]>

Make chroot2 utility responsible for writing a PID of the cloned child
entry point process to the file passed as 5th argument, e.g.

  chroot2 /mnt/rootfs / 0 0 /mnt/entrypoint-pid /bin/sh
                            ^^^^^^^^^^^^^^^^^^^
			    file which will be created by
			    the chroot2 and will contain
			    a PID of a container entry
			    point process.

The PID will be used for a container namespace enter in the following
patch.

The `init-initrd` was changed correspondingly and now the script passes
/mnt/entrypoint-pid to the chroot2 as 5th argument.

Signed-off-by: Roman Penyaev <[email protected]>

Once terminal is attached to the Vm console which hosts a container
user can execute `eve-enter-container` script and enter corresponding
container.

Script uses `nsenter -t $pid` and pid is extracted from the
/mnt/entrypoint-pid file, created by the chroot2 utility.

Signed-off-by: Roman Penyaev <[email protected]>

The application console section describes usage of application
consoles.

Signed-off-by: Roman Penyaev <[email protected]>

Every change in the QEMU config in the 'kvm.go' should
be reflected in the corresponding 'kvm_test.go' file,
otherwise unit-test fails.

Signed-off-by: Roman Penyaev <[email protected]>