init

#!/bin/busybox sh

rescue_shell() {
    echo "$@"
    echo "Something went wrong. Dropping you to a shell."
    busybox --install -s
    exec /bin/sh
}

pretty_menu() {
    num=0
    while read menuitem ; do
        if [ $num -gt 0 ] ; then
            echo -n "${num}: "
            echo $menuitem | cut -d "|" -f 4
        else
            defaultitem=$(echo $menuitem | cut -d "|" -f 1)
            menutimeout=$(echo $menuitem | cut -d "|" -f 2)
        fi
        num=$(expr $num + 1)
    done < /mnt/boot/menu.lst
    echo
}

read_selection() {
    while [[ -z "${selecteditemindex}" || -z "${selectedline}" ]] ; do
        read -t $menutimeout -p "Select an option (default is ${defaultitem} timeout is ${menutimeout}): " selecteditem || selecteditem=$defaultitem
        if [[ $selecteditem -eq $selecteditem ]]; then
            selecteditemindex=$(expr $selecteditem + 1)
            selectedline=$(sed -n ${selecteditemindex}p /mnt/boot/menu.lst)
            selectedtype=$(echo $selectedline | cut -d "|" -f 1)
            selectedroot=$(echo $selectedline | cut -d "|" -f 2)
            selectedoptions=$(echo $selectedline | cut -d "|" -f 3)
            selectedname=$(echo $selectedline | cut -d "|" -f 4)
        fi
    done
}

show_bootmenu() {
    # mountimg /boot
    mkdir -p /mnt/boot
    mount /dev/mmcblk0p1 /mnt/boot || rescue_shell "Error while mounting /boot"

    # print boot menu
    pretty_menu || rescue_shell "Error while printing boot menu"

    # read selected menu item
    read_selection || rescue_shell "Error while reading selection"

    # umounting /boot
    umount /mnt/boot || rescue_shell "Error while umounting /boot"
}

activate_vgs() {
    /sbin/pvscan --uuid --verbose || rescue_shell "Error while scanning physical volumes"
    /sbin/vgscan --mknodes --verbose || rescue_shell "Error while scanning volume groups"

    for vg in $(/sbin/vgscan | grep "Found volume group" | cut -d\" -f2) ; do
        echo "Activating volume group: $vg"
        /sbin/vgchange -ay $vg --sysinit || rescue_shell "Error while activating $vg"
        /sbin/vgmknodes --ignorelockingfailure $vg || rescue_shell "Error while making nodes for $vg"
    done
}

find_rootfs() {
    if [ -z "${selectedoptions}" ] ; then
        mountoptions="ro"
    else
        mountoptions="ro,${selectedoptions}"
    fi
    case $selectedtype in
        phy|lvm)
            fstype=$(echo $selectedroot | cut -d "=" -f 1)
            if [ "${fstype}" == "LABEL" ] || [ "${fstype}" == "UUID" ] ; then
                fsname=$(echo $selectedroot | cut -d "=" -f 2)
                echo "Mounting rootfs: mount -o $mountoptions $(findfs "${fstype}=${fsname}") /mnt/root"
                mount -o $mountoptions $(findfs "${fstype}=${fsname}") /mnt/root
                return
            else
                echo "Mounting rootfs: mount -o $mountoptions ${selectedroot} /mnt/root"
                mount -o $mountoptions $selectedroot /mnt/root
                return
            fi
        ;;
        nfs)
            echo "Mounting rootfs: mount -o ${selectedoptions} ${selectedroot} /mnt/root"
            mount -o $mountoptions $selectedroot /mnt/root
            return
        ;;
    esac

    rescue_shell "No root partition found"
}

pretty_bootmsg() {
    echo
    echo "Booting ${selectedname} (${selectedroot})..."
}

# temporarily mount proc and sys
mount -t proc none /proc
mount -t sysfs none /sys
mount -t devtmpfs none /dev

# disable kernel messages from popping onto the screen
echo 0 > /proc/sys/kernel/printk

# clear the screen
clear

# display the boot menu
show_bootmenu || rescue_shell "Error while reading boot menu"

# scan for vgs and activate each and every one of them
activate_vgs || rescue_shell "Error while activating volume groups"

# mounting rootfs on /mnt/root
find_rootfs || rescue_shell "Error while finding root filesystem"

# print boot message
pretty_bootmsg || rescue_shell "Error while printing boot message"

# find and check mount points
find_mountpoints || rescue_shell "Error while reading and checking mount points"

echo "All done. Switching to real root."

# clean up. The init process will remount proc sys and dev later
umount /proc
umount /sys
umount /dev

# switch to the real root and execute init
exec switch_root /mnt/root /sbin/init