update/blobs/*: simplify mrc.bin handling

mrc.bin is now handled by include/mrc.sh, adapted
from now-deleted script/update/blobs/mrc

much of the logic has been re-written or adapted for
inside script/update/blobs/download

mrc links/hashes now defined in config/blobs/sources

the new code is simpler (and smaller). in addition,
lbmk can now easily handle mrc.bin files for other
platforms such as broadwell. watch this space.

the full .zip download is now cached, like with other
vendor downloads. this means it won't be re-downloaded
if it was already downloaded before.

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/include/mrc.sh b/include/mrc.sh
new file mode 100755
index 00000000..b9345b92
--- /dev/null
+++ b/include/mrc.sh
@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+# Logic based on util/chromeos/crosfirmware.sh in coreboot cfc26ce278.
+# Modifications in this version are Copyright 2021 and 2023 Leah Rowe.
+# Original copyright detailed in repo: https://review.coreboot.org/coreboot/
+
+extract_mrc()
+{
+	[ -z "${MRC_board}" ] && err "extract_mrc $MRC_hash: MRC_board not set"
+	[ -z "${CONFIG_MRC_FILE}" ] && \
+		err "extract_mrc $MRC_hash: CONFIG_MRC_FILE not set"
+
+	_file="${MRC_url##*/}"
+	_file="${_file%.zip}"
+	_mrc_destination="${CONFIG_MRC_FILE#../../}"
+	mkdirs "${_mrc_destination}" "extract_mrc" || return 0
+
+	(
+	cd "${appdir}" || err "extract_mrc: !cd ${appdir}"
+	extract_partition ROOT-A "${_file}" root-a.ext2
+	extract_shellball root-a.ext2 chromeos-firmwareupdate-${MRC_board}
+	extract_coreboot chromeos-firmwareupdate-${MRC_board}
+	)
+
+	"${cbfstool}" "${appdir}/"coreboot-*.bin extract -n mrc.bin \
+	    -f "${_mrc_destination}" -r RO_SECTION || \
+	    err "extract_mrc: could not fetch mrc.bin"
+}
+
+extract_partition()
+{
+	NAME=${1}
+	FILE=${2}
+	ROOTFS=${3}
+	_bs=1024
+
+	printf "Extracting ROOT-A partition\n"
+	ROOTP=$( printf "unit\nB\nprint\nquit\n" | \
+	    parted "${FILE}" 2>/dev/null | grep "${NAME}" )
+
+	START=$(( $( echo ${ROOTP} | cut -f2 -d\ | tr -d "B" ) ))
+	SIZE=$(( $( echo ${ROOTP} | cut -f4 -d\ | tr -d "B" ) ))
+
+	dd if="${FILE}" of="${ROOTFS}" bs=${_bs} skip=$(( ${START} / ${_bs} )) \
+	    count=$(( ${SIZE} / ${_bs} )) || \
+	    err "extract_partition: can't extract root file system"
+}
+
+extract_shellball()
+{
+	ROOTFS=${1}
+	SHELLBALL=${2}
+
+	printf "Extracting chromeos-firmwareupdate\n"
+	printf "cd /usr/sbin\ndump chromeos-firmwareupdate ${SHELLBALL}\nquit" \
+	    | debugfs "${ROOTFS}" || err "extract_shellball: debugfs"
+}
+
+extract_coreboot()
+{
+	_shellball=${1}
+	_unpacked=$( mktemp -d )
+
+	printf "Extracting coreboot image\n"
+	[ -f "${_shellball}" ] || \
+	    err "extract_coreboot: shellball missing in google cros image"
+	sh "${_shellball}" --unpack "${_unpacked}" || \
+	    err "extract_coreboot: shellball exits with non-zero status"
+
+	# TODO: audit the f* out of that shellball, for each mrc version.
+	# it has to be updated for each mrc update. we should ideally
+	# implement the functionality ourselves.
+
+	[ -f "${_unpacked}/VERSION" ] || \
+	    err "extract_coreboot: VERSION file missing on google coreboot rom"
+
+	_version=$( cat "${_unpacked}/VERSION" | grep BIOS\ version: | \
+	    cut -f2 -d: | tr -d \  )
+
+	cp "${_unpacked}/bios.bin" "coreboot-${_version}.bin" || \
+	    err "extract_coreboot: cannot copy google cros rom"
+}