#!/bin/bash
# Script to merge all configs and run 'make oldconfig' on it to wade out bad juju.
# Then split the configs into distro-commmon and flavour-specific parts
#
# See this page for more details:
# http://dev.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-configuration

error() {
	printf 'error: %b\n' "$*" >&2
}

die() {
	error "$@"
	exit 1
}

usage() {
	cat <<-EOF
	Usage: ${0##*/} [options] <oldconfig|olddefconfig|editconfig|genconfig>

	Options:
	  -h   This screen.
	EOF

	if [[ $# -gt 0 ]]; then
		echo
		die "$@"
	else
		exit 0
	fi
}

build_one() {
	local arch=$1
	local kernarch

	# Map debian archs to kernel archs.
	case "${arch}" in
	armel) kernarch="arm" ;;
	*)     kernarch="${arch}" ;;
	esac

	echo ""
	echo "***************************************"
	echo "* Processing ${arch} (${kernarch}) ... "

	local O="$(pwd)/build/${arch}"
	mkdir -p "${O}"

	local config
	local archconfdir="${confdir}/${arch}"
	local flavourconfigs=( $(cd "${archconfdir}" && echo *.flavour.config) )

	# Merge configs
	# We merge base.config + common.config + <flavour>.flavour.config

	for config in "${flavourconfigs[@]}"; do
		cat \
			"${base_conf}" \
			"${archconfdir}/common.config" \
			"${archconfdir}/${config}" \
			> "${O}/.config"
		# Call oldconfig or menuconfig
		case ${mode} in
		oldconfig|olddefconfig)
			# Weed out incorrect config parameters
			echo "* Run ${mode} on ${arch}/${config} ..."
			make -j O="${O}" ARCH=${kernarch} "${mode}"
			;;
		editconfig)
			# Interactively edit config parameters
			echo "* ${arch}/${config}: press <Enter> to edit, S to skip"
			read -s -n 1
			case ${REPLY} in
			s|S)
				echo "* Skip: running oldconfig"
				make -j O="${O}" ARCH=${kernarch} oldconfig
				;;
			*)
				echo "* Running menuconfig"
				make -j O="${O}" ARCH=${kernarch} menuconfig
				;;
			esac
			;;
		*)	# Bad!
			die "invalid mode ${mode}"
			;;
		esac

		cat "${O}/.config" > "${archconfdir}/${config}"
		if [[ "${keep}" == "1" ]]; then
			# oldconfig is probably redundant because .config is
		        # likely formatted already at this point, however
		        # this only take a split-second and could flag some
		        # issues.
			make -j O="${O}" ARCH=${kernarch} oldconfig
			make -j O="${O}" ARCH=${kernarch} savedefconfig
			mv "${O}"/.config "CONFIGS/${arch}-${config}"
			mv "${O}"/defconfig "CONFIGS/${arch}-${config}.def"
		fi
	done

	echo "Running splitconfig for ${arch}"
	echo

	# Can we make this more robust by avoiding $tmpdir completely?
	# This approach was used for now because I didn't want to change
	# splitconfig
	pushd "${archconfdir}" >/dev/null
	rm common.config
	"${bindir}/splitconfig"
	mv common.config "${tmpdir}/${arch}.config"
	popd >/dev/null
}

cleanup() {
	rm -rf "${tmpdir}"
}

cd_kerneldir() {
	# We have to be in the top level kernel source directory.
	if [[ ! -f MAINTAINERS || ! -f Makefile ]]; then
		# See if we can find it automatically first.
		local d=$(realpath "${0%/*}/../..")
		cd "${d}"
		if [[ ! -f MAINTAINERS || ! -f Makefile ]]; then
			die "This does not appear to be the kernel source directory."
		else
			echo "Using top kernel dir: ${d}"
		fi
	fi
}

main() {
	# Process use flags first (so -h works nicely).
	local opt
	while getopts "h" opt; do
		case ${opt} in
		h) usage ;;
		*) usage "Invalid option ${opt}" ;;
		esac
	done
	shift $(( OPTIND - 1 ))

	# Process the remaining args.
	local mode=$1
	case ${mode} in
	oldconfig|olddefconfig)  ;; # All is good
	editconfig) ;; # All is good
	genconfig)  ;; # All is good
	*) usage "invalid/missing mode: ${mode}" ;;
	esac

	# Then make sure we're in the right directory.
	cd_kerneldir

	# Set up variables the build func expects.
	local kerneldir=$(pwd)
	local confdir="${kerneldir}/chromeos/config"
	local archs=( x86_64 armel )
	local bindir="${kerneldir}/chromeos/scripts"
	local base_conf="${confdir}/base.config"

	export tmpdir=$(mktemp -d)
	trap cleanup EXIT

	local keep=0
	if [[ "${mode}" == "genconfig" ]]; then
		keep=1
		mode="oldconfig"
		mkdir -p CONFIGS
	fi

	mkdir -p build

	echo "running ${mode} for ${archs[*]}"
	echo ""
	for arch in "${archs[@]}"; do
		build_one "${arch}"
	done

	# Now run splitconfig on all the <arch>.common.config copied to $tmpdir.
	pushd "${tmpdir}" >/dev/null
	"${bindir}/splitconfig"
	mv "common.config" "${base_conf}"
	for arch in "${archs[@]}"; do
		mv "${arch}.config" "${confdir}/${arch}/common.config"
	done
}
main "$@"