custom-kernel-install

#!/bin/bash

set -e

FILE=
KVER=
HAVE_MODULES=
SCRIPT=$(realpath ${BASH_SOURCE[0]})

usage() {
    echo "
Usage: $(basename $0) [OPTIONS]
Unpack a kernel and install on this board board

OPTIONS
    -c [J|z|zstd]       pass flag to tar while unpacking
" 1>&$1;
    exit $(($1 - 1));
}

OPT_COMPRESS="zstd"
EXT=""
args=0
while getopts "ch" o; do
    case "${o}" in
        c) OPT_COMPRESS=${OPTARG}; args=$[$args + 2] ;;
        h) usage 1;;
        \?) usage 2;;
    esac
done
shift $args

case "$OPT_COMPRESS" in
    J) EXT="tar.xz"; OPT_COMPRESS=-J;;
    z) EXT="tar.gz"; OPT_COMPRESS=-z;;
    zstd) EXT="tar.zstd"; OPT_COMPRESS="-I zstd";;
    "") EXT=".tar";;
    \?) usage 2;;
esac

installkernel=$(which installkernel || true)
kernel_install=$(which kernel-install || true)

if [ $# -gt 0 ]; then
    FILE=$1
    KVER=$(basename $FILE)
    KVER=${KVER/linux-}
    KVER=${KVER//${EXT}}
    HAVE_MODULES=$(tar -tf $FILE ${OPT_COMPRESS} usr/lib/modules/$KVER | head -n 1)
else
    FILE=$SCRIPT
    KVER=$(basename $FILE)
    KVER=${KVER/linux-}
    KVER=${KVER//.sh}
    KVER=${KVER//${EXT}}

    # check if we have embedded custom kernel
    if grep --quiet -e "^__CUSTOM_KERNEL_BELLOW__" ${SCRIPT}; then
	echo "Found kernel $KVER embedded in script, extracting..." >&2
	HAVE_MODULES=$(sed -e '1,/^__CUSTOM_KERNEL_BELLOW__/d' ${SCRIPT} | \
		tar -t ${OPT_COMPRESS} usr/lib/modules/$KVER | head -n 1)
    fi
fi

# sanity check if file has that module directory
if [ -z "$HAVE_MODULES" ]; then
    echo "wrong file name or kernel doesn't have any modules directory" >&2
    exit 1
fi

# remove previous modules
rm -rf /usr/lib/modules/$KVER

if [ ! -z "$kernel_install" ]; then
    # remove previous kernel
    kernel-install remove $KVER
fi

# install kernel and modules on /usr/lib
if [[ !  "$FILE" = "$SCRIPT" ]]; then
    tar -C / -mxf $FILE ${OPT_COMPRESS}
else
    sed -e '1,/^__CUSTOM_KERNEL_BELLOW__/d' ${SCRIPT} | \
            tar -C / -mx ${OPT_COMPRESS}
fi

# target didn't adhere to the /usr move
if [ "$(realpath /lib/modules)" != "/usr/lib/modules" ]; then
    rm -rf /lib/modules/$KVER
    mv /usr/lib/modules/$KVER /lib/modules/$KVER
fi

# copy kernel to boot partition, install bootloader entry and possibly
# generate an initrd
if [ ! -z "$installkernel" ]; then
    $installkernel $KVER /usr/lib/custom-kernel/{vmlinuz,System.map}
elif [ ! -z "$kernel_install" ]; then
    $kernel_install add $KVER /usr/lib/custom-kernel/vmlinuz
else
    echo "Warning: neither kernel-install or installkernel available to install a kernel" >&2
    echo "Just going to install the kernel, bootloader config is on you" >&2
    cp /usr/lib/custom-kernel/vmlinuz /boot/${2:-vmlinuz-test}
fi

echo "Done."