#!/bin/sh
set -e

# The hostname and hostid of the last system to access a ZFS pool are stored in
# the ZFS pool itself. A pool is foreign if, during `zpool import`, the
# current hostname and hostid are different than the stored values thereof.
#
# The only way of having a stable hostid is to define it in /etc/hostid.
# This postinst helper will check if we already have the hostid stabilized by
# checking the existence of the file /etc/hostid to be 4 bytes at least.
# If this file don't already exists on our system or has less than 4 bytes, then
# a new (random) value is generated with zgenhostid (8) and stored in
# /etc/hostid

if [ ! -f /etc/hostid ] || [ "$(stat -c %s /etc/hostid)" -lt 4 ] ; then
	zgenhostid
fi

# When processed to here but zfs kernel module is not loaded, the subsequent
# services would fail to start. In this case the installation process just
# fails at the postinst stage. The user could do
#   $ sudo modprobe zfs; sudo dpkg --configure -a
# to complete the installation.
#
modprobe -v zfs || true # modprobe zfs does nothing if zfs.ko was already loaded.

#DEBHELPER#