#
# Copyright 2021 Google LLC
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# version 2 as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#

# Check for EAPI 5+
case "${EAPI:-0}" in
0|1|2|3|4) die "Unsupported EAPI=${EAPI:-0} (too old) for ${ECLASS}" ;;
5|6) inherit eapi7-ver ;;
7) ;;
esac

inherit linux-info linux-mod toolchain-funcs

IUSE="
	+clang
	+llvm_ias
	module_sign
	platform-key
"

REQUIRED_USE="
	llvm_ias? ( clang )
"

DEPEND="
	platform-key? ( sys-boot/platform-key )
	virtual/linux-sources
"

# Because our kernel version string ends with '+' (e.g.
# "4.4.21+"), Gentoo Linux's linux-info.eclass cannot locate the kernel build
# output directory. Hence we set it up here.
KBUILD_OUTPUT="${KERNEL_DIR}"/build

cos-linux-mod_src_prepare() {
	# Allowing gcc to be used when clang is not set.
	# This is copied from cros-kernel2.eclass to make sure the third
	# party kernel module uses the same compiler as kernel.
	use clang || cros_use_gcc

	default
}

cos-linux-mod_src_compile() {
	BUILD_PARAMS="${BUILD_PARAMS} CC=${CC} LD=${LD}"
	# Assemble with LLVM's integrated assembler on x86_64 and aarch64
	if use llvm_ias; then
		export LLVM_IAS=1
	fi
	linux-mod_src_compile
}

cos-linux-mod_src_install() {
	local key_path="${KBUILD_OUTPUT}"/certs
	if use platform-key ; then
		key_path="${ROOT}"/build/share/platform-key
	fi
	if use module_sign ; then
		for i in ${MODULE_NAMES}
		do
			unset libdir srcdir objdir
			for n in $(find_module_params ${i})
			do
				eval ${n/:*}=${n/*:/}
			done
			libdir=${libdir:-misc}
			srcdir=${srcdir:-${S}}
			objdir=${objdir:-${srcdir}}

			einfo "Signing ${modulename} module"
			cos-linux-mod_sign "${objdir}/${modulename}.${KV_OBJ}" "${key_path}"
			# Do not strip signature
			dostrip -x "/lib/modules/${KV_FULL}/${libdir}/${modulename}.${KV_OBJ}"
		done
	fi

	linux-mod_src_install
}

cos-linux-mod_sign() {
	local module_file="$1"
	local key_path="$2"
	"${KBUILD_OUTPUT}"/scripts/sign-file \
		sha256 \
		"${key_path}"/signing_key.pem \
		"${key_path}"/signing_key.x509 \
		"${module_file}" || die "failed to sign a module"
}

cos-linux-mod_sign_detached() {
	local module_file="$1"
	local key_path="$2"
	"${KBUILD_OUTPUT}"/scripts/sign-file \
		-p \
		sha256 \
		"${key_path}"/signing_key.pem \
		"${key_path}"/signing_key.x509 \
		"${module_file}" || die "failed to sign a module"
}