#!/bin/bash

# Copyright (C) 2007, 2008, 2009 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.

set -e

. common.sh

TMPDIR=`mktemp -d` || exit 1
CLEANUP+=("rmdir $TMPDIR")

# If the target device is not a real block device we'll first losetup it.
# This is needed for file disks.
if [ ! -b $blockdev ]; then
  ORIGINAL_BLOCKDEV=$blockdev
  blockdev=$(losetup -sf $blockdev)
  CLEANUP+=("losetup -d $blockdev")
fi

if [ "$PARTITION_STYLE" = "none" ]; then
  filesystem_dev=$blockdev
elif [ "$PARTITION_STYLE" = "msdos" ]; then
  filesystem_dev=$(map_disk0 $blockdev)
  CLEANUP+=("unmap_disk0 $blockdev")
else
  echo "Unknown partition style $PARTITION_STYLE"
  exit 1
fi

mount $filesystem_dev $TMPDIR
CLEANUP+=("umount $TMPDIR")

HNAME="$TMPDIR/etc/hostname"
MNAME="$TMPDIR/etc/mailname"

# for hostname, we raise and error if the old hostname is not what we
# expect
OLD_HNAME="`cat $HNAME`"
if [ "$OLD_HNAME" = "$old_name" ]; then
	echo $instance > $HNAME
else
	log_error "Cannot rename from $old_name to $instance:"
	log_error "Instance has a different hostname ($OLD_HNAME)"
	exit 1
fi

# for mailname, we rename only if it has the old name, otherwise we
# ignore it (and assumme that it's a customized name)
if [ "`cat $MNAME`" = "$old_name" ]; then
	echo $instance > $MNAME
fi

# execute cleanups
cleanup
trap - EXIT

exit 0