extlinux-conf-builder: don't emit MENU when timeout is zero (#318778)

}

timeout=                # Timeout in centiseconds

menu=1                  # Enable menu by default

default=                # Default configuration

target=/boot            # Target directory

numGenerations=0        # Number of other generations to include in the menu

while getopts "t:c:d:g:n:r" opt; do

    case "$opt" in

        t) # U-Boot interprets '0' as infinite and negative as instant boot

        t) # U-Boot interprets '0' as infinite

            if [ "$OPTARG" -lt 0 ]; then

                # When negative (or null coerced to -1), disable timeout which means that we wait forever for input

                timeout=0

            elif [ "$OPTARG" = 0 ]; then

                timeout=-10

                # When zero, which means disabled in Nix module, disable menu which results in instant boot of the default item

                # .. timeout is actually ignored by u-Boot but set here for the rest of the script

                timeout=1

                menu=0

            else

                # Positive results in centi-seconds of timeout, which when passed with no input results in boot of the default item

                timeout=$((OPTARG * 10))

            fi

            ;;

# Change this to e.g. nixos-42 to temporarily boot to an older configuration.

DEFAULT nixos-default

MENU TITLE ------------------------------------------------------------

TIMEOUT $timeout

EOF

[ "$menu" == "1" ] \

  && echo "MENU TITLE ------------------------------------------------------------" >> $tmpFile

addEntry $default default >> $tmpFile

if [ "$numGenerations" -gt 0 ]; then