control: bump standards version to 3.9.8

[mirror_spl-debian.git] / debian / spl-modules-_KVERS_.postinst.in

#!/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 hostid on Solaris is intrinsic, but is not on Linux (see #595790), so the
# spl kernel module invokes /usr/bin/hostid from the userland in its initialization
# routine.
#
# /usr/bin/hostid will return the 4 first bytes of the file /etc/hostid.
# If this file is not present or contains less than 4 bytes, then /usr/bin/hostid
# will return the bytes of the IP address of $(hostname) flipped, or zero if
# such IP couldn't be obtained
#
# This means that things like a DHCP lease change can affect the hostid.
#
# Therefore the only way of having a stable hostid is to define it on /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
# we will stabilize our current hostid by writing its value to /etc/hostid

# Run depmod first
depmod

# Deal with hostid issue as usual
if [ ! -f /etc/hostid ] || [ $(stat -c %s /etc/hostid) -lt 4 ] ; then

	# Write our current hostid to /etc/hostid
	HOSTID=$(hostid)
	AA=$(echo $HOSTID | cut -b 1,2)
	BB=$(echo $HOSTID | cut -b 3,4)
	CC=$(echo $HOSTID | cut -b 5,6)
	DD=$(echo $HOSTID | cut -b 7,8)

	# Big Endian
	if echo | gcc -E -dM - | grep -q "__BYTE_ORDER__.*__ORDER_BIG_ENDIAN__"; then
		# Invoke the printf from coreutils. shell builtin lacks the byte format.
		/usr/bin/printf "\x$AA\x$BB\x$CC\x$DD" >/etc/hostid
	else
	# Little Endian
		/usr/bin/printf "\x$DD\x$CC\x$BB\x$AA" >/etc/hostid
	fi
fi

#DEBHELPER#