armbian-build/lib/functions/compilation/patch/drivers-harness.sh

function kernel_drivers_create_patches_hash_only() {
	hash_only="yes" kernel_drivers_create_patches "${@}"
}

function kernel_drivers_create_patches() {
	kernel_drivers_patch_hash="undetermined" # outer scope
	kernel_drivers_patch_file="undetermined" # outer scope

	declare hash_files # any changes in these files will trigger a cache miss; also any changes in misc .patch with "wireless" at start or "wifi" anywhere in the name
	calculate_hash_for_files "${SRC}/lib/functions/compilation/patch/drivers_network.sh" "${SRC}/lib/functions/compilation/patch/drivers-harness.sh" "${SRC}"/patch/misc/wireless*.patch "${SRC}"/patch/misc/*wifi*.patch

	declare cache_key_base="${KERNEL_MAJOR_MINOR}_${LINUXFAMILY}"
	declare cache_key="${cache_key_base}_${hash_files}"
	display_alert "Cache key base:" "$cache_key_base" "debug"
	display_alert "Cache key:" "$cache_key" "debug"

	declare cache_dir_base="${SRC}/cache/patch/kernel-drivers"
	mkdir -p "${cache_dir_base}"

	declare cache_target_file="${cache_dir_base}/${cache_key}.patch"

	# outer scope variables:
	kernel_drivers_patch_file="${cache_target_file}" # outer scope
	kernel_drivers_patch_hash="${hash_files}"        # outer scope

	if [[ "${hash_only:-"no"}" == "yes" ]]; then
		display_alert "Hash-only kernel driver requested" "$kernel_drivers_patch_hash - returning" "debug"
		return 0
	fi

	declare kernel_work_dir="${1}"
	declare kernel_git_revision="${2}"

	# If the target file exists, we can skip the patch creation.
	if [[ -f "${cache_target_file}" ]]; then
		# Make sure the file is larger than 512 bytes. Old versions of this code left small/empty files on failure.
		if [[ $(stat -c%s "${cache_target_file}") -gt 512 ]]; then
			display_alert "Using cached drivers patch file for ${LINUXFAMILY}-${KERNEL_MAJOR_MINOR}" "${cache_key}" "cachehit"
			return
		else
			display_alert "Removing invalid/small cached drivers patch file for ${LINUXFAMILY}-${KERNEL_MAJOR_MINOR}" "${cache_key}" "warn"
			run_host_command_logged rm -fv "${cache_target_file}"
		fi
	fi

	display_alert "Creating patches for kernel drivers" "version: '${KERNEL_MAJOR_MINOR}' family: '${LINUXFAMILY}'" "info"

	# if it does _not_ exist, fist clear the base, so no old patches are left over
	run_host_command_logged rm -fv "${cache_dir_base}/${cache_key_base}*"

	# since it does not exist, go create it. this requires working tree.
	declare target_patch_file="${cache_target_file}"

	display_alert "Preparing patch for drivers" "version: ${KERNEL_MAJOR_MINOR} kernel_work_dir: ${kernel_work_dir}" "debug"

	kernel_drivers_prepare_harness "${kernel_work_dir}" "${kernel_git_revision}"
}

function kernel_drivers_prepare_harness() {
	declare kernel_work_dir="${1}"
	declare kernel_git_revision="${2}"
	# outer scope variable: target_patch_file

	declare -a drivers=(
		driver_generic_bring_back_ipx
		driver_rtl8152_rtl8153
		driver_rtl8189ES
		driver_rtl8189FS
		driver_rtl8192EU
		driver_rtl8811_rtl8812_rtl8814_rtl8821
		driver_xradio_xr819
		driver_rtl8811CU_rtl8821C
		driver_rtl8188EU_rtl8188ETV
		driver_rtl88x2bu
		driver_rtl88x2cs
		driver_rtl8822cs_bt
		driver_rtl8723DS
		driver_rtl8723DU
		driver_rtl8822BS
		driver_uwe5622_allwinner
	)

	# change cwd to the kernel working dir
	cd "${kernel_work_dir}" || exit_with_error "Failed to change directory to ${kernel_work_dir}"

	#run_host_command_logged git status
	run_host_command_logged git reset --hard "${kernel_git_revision}"
	# git: remove tracked files, but not those in .gitignore
	run_host_command_logged git clean -fd # no -x here

	for driver in "${drivers[@]}"; do
		display_alert "Preparing driver" "${driver}" "info"

		# reset variables used by each driver
		declare version="${KERNEL_MAJOR_MINOR}"
		declare kernel_work_dir="${1}"
		declare kernel_git_revision="${2}"
		# for compatibility with `master`-based code
		declare kerneldir="${kernel_work_dir}"
		declare EXTRAWIFI="yes" # forced! @TODO not really?

		# change cwd to the kernel working dir
		cd "${kernel_work_dir}" || exit_with_error "Failed to change directory to ${kernel_work_dir}"

		# invoke the driver; non-armbian-next code.
		"${driver}"

		# recover from possible cwd changes in the driver code
		cd "${kernel_work_dir}" || exit_with_error "Failed to change directory to ${kernel_work_dir}"
	done

	# git: check if there are modifications
	if [[ -n "$(git status --porcelain)" ]]; then
		display_alert "Drivers have modifications" "exporting patch into ${target_patch_file}" "info"
		export_changes_as_patch_via_git_format_patch
	else
		exit_with_error "Applying drivers didn't produce changes."
	fi
}

function export_changes_as_patch_via_git_format_patch() {
	# git: add all modifications
	run_host_command_logged git add .

	declare -a common_envs=(
		"HOME=${HOME}"
		"PATH=${PATH}"
	)

	# git: commit the changes
	declare -a git_params=(
		"-c" "commit.gpgsign=false" # force gpgsign off; the user might have it enabled and it will fail.
	)
	declare -a commit_params=(
		"--quiet" # otherwise too much output
		-m "drivers for ${LINUXFAMILY} version ${KERNEL_MAJOR_MINOR}"
		--author="${MAINTAINER} <${MAINTAINERMAIL}>"
	)
	declare -a commit_envs=(
		"GIT_COMMITTER_NAME=${MAINTAINER}"
		"GIT_COMMITTER_EMAIL=${MAINTAINERMAIL}"
	)
	run_host_command_logged env -i "${common_envs[@]@Q}" "${commit_envs[@]@Q}" git "${git_params[@]@Q}" commit "${commit_params[@]@Q}"

	# export the commit as a patch
	declare formatpatch_params=(
		"-1" "--stdout"
		"--unified=3"    # force 3 lines of diff context
		"--keep-subject" # do not add a prefix to the subject "[PATCH] "
		# "--no-encode-email-headers" # do not encode email headers - @TODO does not exist under focal, disable
		'--signature' "Armbian generated patch from drivers for kernel ${version} and family ${LINUXFAMILY}"
		'--stat=120'            # 'wider' stat output; default is 80
		'--stat-graph-width=10' # shorten the diffgraph graph part, it's too long
		"--zero-commit"         # Output an all-zero hash in each patch’s From header instead of the hash of the commit.
	)

	declare target_patch_file_tmp="${target_patch_file}.tmp"
	# The redirect ">" is escaped here, so it's run inside the subshell, not in the current shell.
	run_host_command_logged env -i "${common_envs[@]@Q}" git format-patch "${formatpatch_params[@]@Q}" ">" "${target_patch_file_tmp}"

	# move the tmp to final, if it worked.
	run_host_command_logged mv -v "${target_patch_file_tmp}" "${target_patch_file}"
}