pre_upgrade() {
  cp -f /etc/pacman.conf /etc/pacman.conf.upgrade_backup
  cp -f /etc/makepkg.conf /etc/makepkg.conf.upgrade_backup
}

post_upgrade() {
  cp -f /etc/pacman.conf.upgrade_backup /etc/pacman.conf
  cp -f /etc/makepkg.conf.upgrade_backup /etc/makepkg.conf
}

op=$1
shift
$op $*