log() {
        echo "$@" 1>&2
}
fatal() {
        log "$0: $@"
        exit 1
}
in_chromeos() {
        [ -f /usr/sbin/chromeos-postinst ]
}
in_chroot() {
        [ ! -f /usr/sbin/chromeos-postinst ]
}
assert() {
        eval "$@" || fatal "failed assertion: $@"
}
# Usage: matches_rx <string> <rx>
matches_rx() {
        local value="$1"
        local rx="$2"
        echo $value | egrep -q "$rx"
}
check_crossystem() {
        $dry_run sudo $hack/chromeos-files/crossystem dev_boot_signed_only=0
        [ "$(sudo $hack/chromeos-files/crossystem dev_boot_signed_only)" = 0 ] || \
                fatal "WARNING - dev_boot_signed_only is set, danger, FIX BEFORE REBOOT!"
}