#!/bin/bash
# Just a simple wrap to execute extra commands when building kernel and initramfs from genkernel.
# -------------------------------------------------------------------------------
# "THE BEER-WARE LICENSE" (Revision 42):
# <aline@alinefreitas.com.br> wrote this file.  As long as you retain this notice 
# you can do whatever you want with this stuff. If we meet some day, and you think
# this stuff is worth it, you can buy me a beer in return.   Aline Freitas
# -------------------------------------------------------------------------------

# EFI boot dir.
_efiPath=/boot/EFI/Boot
_imagePath=/usr/src/linux/arch/x86/boot
_rootDevice=/dev/sda

# In _args we get any arguments except the last (_action).
array=($@)
len=${#array[@]}
_action=${array[$len-1]}
_args=${array[@]:0:$len-1}

# Check if our $UID = 0
if [ "$(id -u)" != "0" ]; then
    echo "Sorry, you are not root."
    exit 1
fi

# Check if our directories exist.
if [[ ! -d $_efiPath ]]; then
    mount /boot
fi

if [[ ! -d $_imagePath ]] || [[ ! -d $_efiPath ]]; then
    echo "$_imagePath or $_efiPath does not exist"
    exit 1
fi

# If the user gives only one argument, this one should be _action.
if [ $# = 1 ]; then
    _action=$1
    unset _args
elif [ $# = 0 ]; then
    /usr/bin/genkernel --help
fi

# Get kernel version from kernel image.
kernversion () {
    echo $(file $1 | grep -Po '(?<=version)\W*\K[^ ]*')
}

case $_action in
    all)
        # Execute genkernel and if successful check if the kernel image exist.
        echo "Executing genkernel $_args all..."
        /usr/bin/genkernel $_args all && [[ -f $_imagePath/bzImage ]]

        builtkernver=$(kernversion $_imagePath/bzImage)
        currentkernver=$(kernversion $_efiPath/bootx64.efi)

        # Compare built image kernel version with existent in EFI.
        if [[ $builtkernver != $currentkernver ]]; then
            echo "Moving current kernel to bootx64.old.efi..."
            cp $_efiPath/bootx64{,.old}.efi
        fi
        echo "Installing bzImage to bootx64.efi..."
        cp $_imagePath/bzImage $_efiPath/bootx64.efi
        if ! efibootmgr -v grep -qi 'efi\\boot\\bootx64.efi'; then
          find /boot -iwholename /boot/efi/boot/bootx64.efi && \
            efibootmgr -c -d ${_rootDevice} -p 1 -L "Gentoo" -l "\EFI\Boot\Bootx64.efi"
        fi
        if ! efibootmgr -v grep -qi 'efi\\boot\\bootx64.old.efi'; then
          find /boot -iwholename /boot/efi/boot/bootx64.efi && \
            efibootmgr -c -d ${_rootDevice} -p 1 -L "Gentoo OLD" -l "\EFI\Boot\Bootx64.old.efi"
        fi
        ;;
    *)
        /usr/bin/genkernel $_args $_action
        ;;
esac