-#!/bin/sh -e
-
+#!/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 hostname and hostid on Solaris are intrinsic, but they are not on Linux,
-# so the spl kernel module invokes /bin/hostname and /usr/bin/hostid from the
-# userland in its initialization routine.
+# 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.
#
-# However, these two indentifiers are usually undefined in the Linux initramfs
-# environment, so the /etc/hostname and /etc/hostid files must be added to the
-# initrd. Things like a DHCP lease change can affect the hostid too.
+# /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 $(hostname) flipped, or zero if
+# such IP couldn't be obtained
#
-# ZFS requires stable values for hostname and hostid, but basic Linux systems
-# do not. The hostid is therefore stabilized by creating the /etc/hostid file
-# in the regular environment if it does not already exist. An undefined
-# hostname is usuallly stable.
+# This means that things like a DHCP lease change can affect the hostid.
#
-# Neither /etc/hostname nor /etc/hostid are controlled configuration files in
-# Debian distributions, but the spl package nevertheless installs a dummy
-# /etc/hostid file that contains the HW_INVALID_HOSTID sentinal value so that
-# the package manager will track it.
-
-# This result is always an eight-character hexadecimal number sans the 0x
-# prefix. Remember that /usr/bin/hostid generates a value if the /etc/hostid
-# file doesn't exist or is malformed.
-HOSTID=$(hostid)
-
-if [ -f /etc/hostid -a "0x$HOSTID" != "0xffffffff" ]
-then
- # This system already has a stable hostid.
- exit 0
+# 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
+
+# Detect if /etc/hostid is a conffile of previous spl package, migrate if yes
+# hostid file should preserve even when package is purged
+if $(dpkg-query --showformat='${Conffiles}\n' --show spl >/dev/null 2>&1); then
+ dpkg-maintscript-helper rm_conffile /etc/hostid -- "$@"
fi
-# Truncate the dummy file and generate the actual system hostid.
-: >/etc/hostid
-HOSTID=$(hostid)
-
-# @TODO: Check whether this method is appropriate for gethostid(2) on big
-# endian systems. (Update: It isn't.)
-#
-# The /etc/hostname file on i386 and amd64 systems must be a little endian
-# integer of exacly four bytes. Regardless, a consistent hostid is more
-# important than a correct byte order here.
-
-# Conveniences like a ${HOSTID:$ii:2} substring range or a `sed` one-liner
-# are prohibited here because this file must be dash-compatible by policy.
-AA=$(echo $HOSTID | cut -b 1,2)
-BB=$(echo $HOSTID | cut -b 3,4)
-CC=$(echo $HOSTID | cut -b 5,6)
-DD=$(echo $HOSTID | cut -b 7,8)
-
-# Invoke the external printf because the dash builtin lacks the byte format.
-"$(which printf)" "\x$DD\x$CC\x$BB\x$AA" >"/etc/hostid"
-
-# @ASSERT: [ "$HOSTID" = "$(hostid)" ]
+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 -n I | od -to2 | awk 'FNR==1{ print substr($2,6,1)}' 2>/dev/null) = 0 ]; then
+ # Invoke the printf from coreutils. shell builtin lacks the byte format.
+ /usr/bin/printf "\x$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#
projects / mirror_spl-debian.git / blobdiff