[Libguestfs] Weird results from g.sh()

[Richard W.M. Jones]

On Thu, Aug 27, 2020 at 11:24:57AM +0300, Sam Eiderman wrote:
> Yes, I understand that, I am just surprised to know that we bind /sys
> for g.sh() commands.
> 
> However, "g.command([self.mkconfig, '-o', self.config])" shouldn't
> have the appliances /sys available (I looked briefly in command.c and
> I don't see the same bind-mount code), or maybe I'm missing something.

guestfs_sh, guestfs_sh_lines, guestfs_command, guestfs_command_lines
all attempt to bind-mount /sys and other directories into the chroot
while running the command.  (See daemon/sh.c)

Anyway I misunderstood before - I thought you were trying to run grub
to install the bootloader.  Running grub2-mkconfig as done in virt-v2v
should be fine since AIUI it's just concatenating some configuration
files together.

> I thought I could use my g.mkdir_p('/sys/firmware/efi') hack, but
> since it didn't work, I'm now resort to explicitly handling this
> failure after running the mkconfig command:

The mkdir didn't work since that directory will be covered by the bind
mount when the command is running.

I'm not sure there's a good answer here, maybe something like:

  g.sh ("
    mkdir -p /sys/firmware/efi
    # create some files in /sys/firmware/efi to trick grub
    grub2-mkconfig -o ...
  ")

although this may modify the appliance's real /sys.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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