mrc.sh: general code cleanup

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

include/mrc.sh

@@ -4,7 +4,7 @@
 # Modifications in this version are Copyright 2021 and 2023 Leah Rowe.
 # Original copyright detailed in repo: https://review.coreboot.org/coreboot/
 
-eval "$(setvars "" MRC_url MRC_url_bkup MRC_hash MRC_board ROOTFS SHELLBALL)"
+eval "$(setvars "" MRC_url MRC_url_bkup MRC_hash MRC_board SHELLBALL)"
 
 extract_mrc()
 {
@@ -12,13 +12,13 @@ extract_mrc()
 	[ -z "${CONFIG_MRC_FILE}" ] && \
 		err "extract_mrc $MRC_hash: CONFIG_MRC_FILE not set"
 
-	ROOTFS="root-a.ext2"
 	SHELLBALL="chromeos-firmwareupdate-${MRC_board}"
 
 	(
 	x_ cd "${appdir}"
-	extract_partition
-	extract_shellball
+	extract_partition "${MRC_url##*/}"
+	printf "cd /usr/sbin\ndump chromeos-firmwareupdate ${SHELLBALL}\nquit" \
+	    | debugfs "root-a.ext2" || err "extract_mrc: can't extract shellball"
 	extract_archive "${SHELLBALL}" .
 	) || err "mrc download/extract failure"
 
@@ -28,26 +28,14 @@ extract_mrc()
 
 extract_partition()
 {
-	NAME="ROOT-A"
-	FILE="${MRC_url##*/}"
-	FILE="${FILE%.zip}"
-	_bs=1024
-
 	printf "Extracting ROOT-A partition\n"
 	ROOTP=$( printf "unit\nB\nprint\nquit\n" | \
-	    parted "${FILE}" 2>/dev/null | grep "${NAME}" )
+	    parted "${1%.zip}" 2>/dev/null | grep "ROOT-A" )
 
 	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, dd ${FILE}, ${ROOTFS}"
-}
-
-extract_shellball()
-{
-	printf "Extracting chromeos-firmwareupdate\n"
-	printf "cd /usr/sbin\ndump chromeos-firmwareupdate ${SHELLBALL}\nquit" \
-	    | debugfs "${ROOTFS}" || err "extract_shellball: debugfs"
+	dd if="${1%.zip}" of="root-a.ext2" bs=1024 \
+	    skip=$(( ${START} / 1024 )) count=$(( ${SIZE} / 1024 )) || \
+	    err "extract_partition, dd ${1%.zip}, root-a.ext2"
 }