fw

#!/bin/sh

device=/dev/mmcblk0
rootdev=`readlink /dev/root`

if [ "Xmmcblk0p3" == "X$rootdev" ]; then
    update_kernel_part_index=4
    current_kernel_part_index=2
elif [ "Xmmcblk0p5" == "X$rootdev" ]; then
    update_kernel_part_index=2
    current_kernel_part_index=4
else
    echo error
    exit 1
fi

confirm() {                                                              
    cgpt add -i $current_kernel_part_index -S 1 /dev/mmcblk0   
    cgpt prioritize -i $current_kernel_part_index /dev/mmcblk0      
}

update() {
    [ -f "$1" ] || usage

    kernel_sig=`hexdump -n 8 -e '"%_p"' $1`
    rootfs_sig=`hexdump -n 4 -e '"%_p"' $1`

    if [ "XCHROMEOS" == "X$kernel_sig" ]; then
        update_part=/dev/mmcblk0p$update_kernel_part_index
    elif [ "Xhsqs" == "X$rootfs_sig" ]; then
        update_part=/dev/mmcblk0p$(($update_kernel_part_index + 1))
    else
        echo "Unknown file type"
        usage
    fi

    current_success=`cgpt show -i $current_kernel_part_index -S $device`
    if [ "$current_success" -ne 1 ]; then
        echo Cannot update from an unsuccessful partition
        exit 1
    fi

    dd if=$1 of=$update_part
    cgpt add -i $update_kernel_part_index -S 0 -T 1 /dev/mmcblk0
    cgpt prioritize -i $update_kernel_part_index /dev/mmcblk0
}

usage() {
    echo "Usage:"
    echo "$0 update file"
    echo "    Update the kernel or rootfs partition and make it bootable"
    echo "$0 confirm"
    echo "    Set the success flag on current kernel partition"
    echo "$0 boot"
    echo "    Boot the system"
    exit 1
}

boot() {
    cmdline="root=LABEL=root resume=LABEL=swap rootflags=subvol=root"
    mount -r -t ext4 LABEL=boot /boot                                                                                     
    kexec -l /boot/vmlinuz --initrd=/boot/initramfs.img --command-line="$cmdline"
    kexec -e    
}

case "$1" in
boot)
    boot
    ;;
confirm)
    confirm
    ;;
update)
    update $2
    ;;
*)
    usage
    ;;
esac