function unmount_image () {
    # unmount from the chroot
    # Don't use TMP_MOUNT_PATH here, it might not have been set.
    sudo umount -f $TMP_BUILD_DIR/mnt/sys || true
    sudo umount -f $TMP_BUILD_DIR/mnt/proc || true
    sudo umount -f $TMP_BUILD_DIR/mnt/dev || true
    sudo umount -f $TMP_BUILD_DIR/mnt/tmp/in_target.d || true
    # give it a second (ok really 5) to umount XXX - why? should instead track
    # the mount data / lsof etc.
    sleep 5
    # oh ya don't want to forget to unmount the image
    sudo umount -f $TMP_BUILD_DIR/mnt || true
    # having disk corruption issues; one possibility is qemu-nbd not flush dirty
    # pages on disconnect?
    sync
    if [ -n "$EXTRA_UNMOUNT" ]; then
        $EXTRA_UNMOUNT
    fi
}

function cleanup () {
    unmount_image
    rm -rf $TMP_BUILD_DIR
}

function mk_build_dir () {
  export TMP_BUILD_DIR=$(mktemp -t -d image.XXXXXXXX)
  [ $? -eq 0 ] || die "Failed to create tmp directory"
  trap cleanup EXIT
  echo Building in $TMP_BUILD_DIR
  export TMP_IMAGE_PATH=$TMP_BUILD_DIR/image
  export TMP_HOOKS_PATH=$TMP_BUILD_DIR/hooks
}

function ensure_nbd () {
    NBD=`which qemu-nbd`
    if [ -z "$NBD" ];  then
        echo "Need qemu-nbd to build qcow2 files."
	sudo apt-get install qemu-utils
    fi
    # prep nbd for mounting
    (lsmod | grep '^nbd ') || sudo modprobe nbd max_part=16
}

function ensure_base_available () {
    # TODO: don't cache -current forever.
    if [ ! -f $IMG_PATH/$BASE_IMAGE_FILE ] ; then
       echo "Fetching Base Image"
       wget $CLOUD_IMAGES/$RELEASE/current/$BASE_IMAGE_FILE -O $IMG_PATH/$BASE_IMAGE_FILE.tmp
       mv $IMG_PATH/$BASE_IMAGE_FILE.tmp $IMG_PATH/$BASE_IMAGE_FILE
    fi
}

function ensure_sudo () {
    sudo echo "Ensuring sudo is available"
}

function mount_tmp_image () {
  mkdir $TMP_BUILD_DIR/mnt
  sudo mount $@ $TMP_BUILD_DIR/mnt
  [ $? -eq 0 ] || die "Failed to mount image"
  export TMP_MOUNT_PATH=$TMP_BUILD_DIR/mnt
}

function create_base () {
    # Extract the base image
    sudo tar -C $TMP_MOUNT_PATH -xzf $IMG_PATH/$BASE_IMAGE_FILE

    # Configure Image
    # Setup resolv.conf so we can chroot to install some packages
    # XXXX: Should store the old state rather than unlink; then restore later.
    if [ -L $TMP_MOUNT_PATH/etc/resolv.conf ] ; then
        sudo unlink $TMP_MOUNT_PATH/etc/resolv.conf
    fi

    if [ -f $TMP_MOUNT_PATH/etc/resolv.conf ] ; then
        sudo rm -f $TMP_MOUNT_PATH/etc/resolv.conf
    fi

    # Recreate resolv.conf
    sudo touch $TMP_MOUNT_PATH/etc/resolv.conf
    sudo chmod 777 $TMP_MOUNT_PATH/etc/resolv.conf
    echo nameserver 8.8.8.8 > $TMP_MOUNT_PATH/etc/resolv.conf

    # supporting kernel file systems
    sudo mount -t proc none $TMP_MOUNT_PATH/proc
    sudo mount --bind /dev $TMP_MOUNT_PATH/dev
    sudo mount -t sysfs none $TMP_MOUNT_PATH/sys

    # If we have a network proxy, use it.
    if [ -n "$http_proxy" ] ; then
        sudo dd of=$TMP_MOUNT_PATH/etc/apt/apt.conf.d/60img-build-proxy << _EOF_
    Acquire::http::Proxy "$http_proxy";
_EOF_
    fi
}

# Helper function to run a command inside the chroot
function run_in_target() {
   # -E to preserve http_proxy
   sudo -E chroot $TMP_MOUNT_PATH "$@"
}

function generate_hooks () {
  mkdir -p $TMP_HOOKS_PATH
  for _FLAVOUR in $IMAGE_FLAVOUR ; do 
    [ -d $FLAVOURS_DIR/$_FLAVOUR ] || die "The flavour does not exist." ;
    cp -t $TMP_HOOKS_PATH -a $FLAVOURS_DIR/$_FLAVOUR/* ;
  done
}

# Check that a real flavour has been chosen (prevents foot-guns)
function check_flavour () {
  [ -d $TMP_HOOKS_PATH ] || generate_hooks
}

# Helper function to run a directory of scripts inside the chroot
function run_d_in_target() {
    check_flavour
    # If we can find a directory of hooks to run in the target filesystem, bind
    # mount it into the target and then execute run-parts in a chroot
    if [ -d ${TMP_HOOKS_PATH}/$1.d ] ; then
      sudo mkdir $TMP_MOUNT_PATH/tmp/in_target.d
      sudo mount --bind ${TMP_HOOKS_PATH} $TMP_MOUNT_PATH/tmp/in_target.d
      sudo mount -o remount,ro,bind ${TMP_HOOKS_PATH} $TMP_MOUNT_PATH/tmp/in_target.d
      run_in_target run-parts -v /tmp/in_target.d/$1.d
      sudo umount -f $TMP_MOUNT_PATH/tmp/in_target.d
      sudo rmdir $TMP_MOUNT_PATH/tmp/in_target.d
    fi
}

# Run a directory of hooks outside the target.
function run_d() {
    check_flavour
    if [ -d ${TMP_HOOKS_PATH}/$1.d ] ; then
      run-parts ${TMP_HOOKS_PATH}/$1.d
    fi
}

function prepare_first_boot () {
    if [ -d ${TMP_HOOKS_PATH}/first-boot.d ] ; then
      sudo cp -t $TMP_MOUNT_PATH/etc/ -a $TMP_HOOKS_PATH/first-boot.d
      run_in_target mv /etc/rc.local /etc/rc.local.REAL
      sudo dd of=$TMP_MOUNT_PATH/etc/rc.local <<EOF
#!/bin/bash
set -e
set -o xtrace

run-parts -v /etc/first-boot.d
rm -fr /etc/first-boot.d
mv /etc/rc.local.REAL /etc/rc.local
exit 0
EOF
      run_in_target chmod 755 /etc/rc.local
    fi
}

function finalise_base () {
    # Undo our proxy support
    sudo rm -f $TMP_MOUNT_PATH/etc/apt/apt.conf.d/60img-build-proxy
    # Now remove the resolv.conf we created above
    sudo rm -f $TMP_MOUNT_PATH/etc/resolv.conf
    # The we need to recreate it as a link
    sudo ln -sf ../run/resolvconf/resolv.conf $TMP_MOUNT_PATH/etc/resolv.conf
}

function compress_image () {
    # Recreate our image to throw away unnecessary data
    qemu-img convert -c $TMP_IMAGE_PATH -O qcow2 $TMP_IMAGE_PATH-new
    rm $TMP_IMAGE_PATH
    mv $TMP_IMAGE_PATH-new $TMP_IMAGE_PATH
}

function save_image () {
    # TODO: this really should rename the old file
    if [ -f  $1 ] ; then
       echo "Old Image file Found REMOVING"
       rm -f $1
    fi

    cp $TMP_IMAGE_PATH $1
    rm -r $TMP_BUILD_DIR
    # All done!
    trap EXIT
    echo "Image file $1 created..."
}

function block_apt_translations () {
# Configure APT not to fetch translations files
sudo dd of=$TMP_MOUNT_PATH/etc/apt/apt.conf.d/95no-translations <<EOF
APT::Acquire::Languages "none";
EOF

# And now make sure that we don't fall foul of Debian bug 641967
find $TMP_MOUNT_PATH/var/lib/apt/lists/ -type f -name '*_i18n_Translation-*' -exec sudo rm -f {} \;
}

function block_daemons () {
# Prevent package installs from starting daemons
sudo mv $TMP_MOUNT_PATH/sbin/start-stop-daemon $TMP_MOUNT_PATH/sbin/start-stop-daemon.REAL
sudo dd of=$TMP_MOUNT_PATH/sbin/start-stop-daemon <<EOF
#!/bin/sh
echo
echo "Warning: Fake start-stop-daemon called, doing nothing"
EOF
sudo chmod 755 $TMP_MOUNT_PATH/sbin/start-stop-daemon

sudo mv $TMP_MOUNT_PATH/sbin/initctl $TMP_MOUNT_PATH/sbin/initctl.REAL
sudo dd of=$TMP_MOUNT_PATH/sbin/initctl <<EOF
#!/bin/sh
echo "initctl (tripleo 1.0)"
echo "Warning: Fake initctl called, doing nothing"
EOF
sudo chmod 755 $TMP_MOUNT_PATH/sbin/initctl

sudo mv $TMP_MOUNT_PATH/usr/sbin/invoke-rc.d $TMP_MOUNT_PATH/usr/sbin/invoke-rc.d.REAL
sudo dd of=$TMP_MOUNT_PATH/usr/sbin/invoke-rc.d <<EOF
#!/bin/sh
echo "invoke-rc.d (tripleo 1.0)"
echo "Warning: Fake inovke-rc.d called, doing nothing"
EOF
sudo chmod 755 $TMP_MOUNT_PATH/usr/sbin/invoke-rc.d
}

function unblock_daemons () {
  sudo mv $TMP_MOUNT_PATH/sbin/start-stop-daemon.REAL $TMP_MOUNT_PATH/sbin/start-stop-daemon
  sudo mv $TMP_MOUNT_PATH/sbin/initctl.REAL $TMP_MOUNT_PATH/sbin/initctl
  sudo mv $TMP_MOUNT_PATH/usr/sbin/invoke-rc.d.REAL $TMP_MOUNT_PATH/usr/sbin/invoke-rc.d
}

function do_pre_install () {
  block_daemons
  block_apt_translations
  # Install baseline packages and tools
  run_in_target apt-get -y update
  run_in_target apt-get -y install python-software-properties
  run_in_target add-apt-repository -y ppa:tripleo/demo
  # Uncomment to get the bleeding edge - this should be a flavour thing.
  # run_in_target add-apt-repository -y ppa:tripleo/demo-staging
  # Run pre-install scripts. These do things that prepare the chroot for package installs
  run_d_in_target pre-install
  run_in_target apt-get -y update
}

function do_install () {
  # These are useful, or at worst not harmful, for all imges we build.
  run_in_target apt-get -y install linux-image-generic vlan open-iscsi
  # Call install scripts to pull in the software users want.
  run_d_in_target install
  unblock_daemons
}