[lxc-devel] fixing restoring of tty mode after lxc-start

[Michael Tokarev]

Hello.

While trying to fix the tty mode after lxc-start, I come across
lxc_close_all_inherited_fd() routine.  Which closes all fds which
were inherited when lxc-start started.

It's called this way:

  lxc_start.c:main():
    lxc_start():
     lxc_spawn();
     lxc_close_all_inherited_fd()
     lxc_poll()

The question is why lxc_close_all_inherited() is needed here.
And why it is ever needed _outside_ of the container to start
with.

This call to close_all_inherited_fd() is the reason why tty
modes are not restored after lxc-start: because stdin is now
closed and hence nothing to restore.

It looks like the whole inherited_fd thing is only needed in
lxc_init helper binary, there's no need to use it anywhere else.
And even there it can be avoided, by iterating over /proc/self/fd
and closing them on the way.

But maybe there's some other for this housekeeping somewhere, so
I'm asking.

Thanks!

/mjt