_install_notes() {
  echo
  echo '---------------------------------------------------------------------------'
  echo ' IMPORTANT NOTES:'
  echo 
  echo '- Run "vbox_build_module" as root every time your kernel is upgraded, to'
  echo '  compile the module for the new kernel version.'
  echo '- Add your user to the vboxusers group:'
  echo '     gpasswd -a USERNAME vboxusers'
  echo '- Add "vboxdrv" to the MODULES array in your "/etc/rc.conf"'
  echo '- Add "vboxnetflt" to MODULES if you want Host Interface networking.'
  echo '- Add "vboxnetadp" to MODULES if you want Host-Only networking.'
  echo '- If USB does not work for you out-of-the-box, add the following line'
  echo '  to "/etc/fstab":'
  echo '     none /proc/bus/usb usbfs auto,busgid=108,busmode=0775,devgid=108,devmode=0664 0 0'
  echo "---------------------------------------------------------------------------"
}

# $1: The new package version
post_install() {
  # Unload modules (if any)
  for _mod in vbox{drv,netadp,netflt}; do
    modprobe -r $_mod &> /dev/null
  done

  # Build new module
  echo "Building VirtualBox modules..."
  /usr/bin/vbox_build_module &> /dev/null

  # Add vboxusers group, GID 108 is reserved (http://wiki.archlinux.org/index.php/UID_and_GID_list),
  # but in some systems it may be being used - please replace if needed.
  groupadd -f -g 108 vboxusers

  # Create the directory below if it doesn't exist
  mkdir -p "/var/run/VirtualBox"

  # Load new udev rule for module vboxdrv
  udevadm control --reload-rules

  # Show the license
  echo '---------------------------------------------------------------------------' >&2
  echo ' You must agree to the following license in order to use this program:' >&2
  echo >&2
  cat "/opt/VirtualBox/LICENSE" >&2
  echo >&2
  echo '---------------------------------------------------------------------------' >&2

  # Load the new module
  modprobe vboxdrv

  _install_notes
}

# $1: The new package version
# $2: The old package version
post_upgrade() {
  _NEWVERSION=`echo $1 | cut -f-1 -d '-'`
  _OLDVERSION=`echo $2 | cut -f-1 -d '-'`

  # Unload modules (if any)
  for _mod in vbox{drv,netadp,netflt}; do
    modprobe -r $_mod &> /dev/null
  done

  # Remove any stuff (e.g. module compilation files) from an old installation - old versions used
  # to use these directories.
  if [ "$_NEWVERSION" != "$_OLDVERSION" ]; then
    rm -Rf "/opt/VirtualBox-${_OLDVERSION}" &> /dev/null
  fi
  if [ "$1" != "$2" ]; then
    rm -Rf "/opt/virtualbox" &> /dev/null
  fi

  # Create the directory below if it doesn't exist
  mkdir -p "/var/run/VirtualBox"

  # Build new module
  echo "Building VirtualBox modules..."
  /usr/bin/vbox_build_module &> /dev/null
  
  # Load the new module
  modprobe vboxdrv

  _install_notes
}

# $1: The old package version
pre_remove() {
  # Unload modules (if any)
  for _mod in vbox{drv,netadp,netflt}; do
    modprobe -r $_mod &> /dev/null
  done

  # Remove the module files
  rm -f "/lib/modules/`uname -r`/misc/"{vboxdrv,vboxnetadp,vboxnetflt}.ko

  # Remove any stuff remaining from the module compilation
  rm -Rf "/opt/VirtualBox"
}