blobutil/download: split into small functions

This patch makes it easier to determine which part does what.

resources/scripts/blobs/download

@@ -2,9 +2,9 @@
 
 # SPDX-FileCopyrightText: 2022 Caleb La Grange <thonkpeasant@protonmail.com>
 # SPDX-FileCopyrightText: 2022 Ferass El Hafidi <vitali64pmemail@protonmail.com>
+# SPDX-FileCopyrightText: 2023 Leah Rowe <info@minifree.org>
 # SPDX-License-Identifier: GPL-3.0-only
 
-needs=""
 board="${1}"
 # A shorthand for each board, to avoid duplicating configs per flash size
 board_short=${board%%_*mb}
@@ -89,7 +89,7 @@ Download_needed(){
 	for need in ${needs}; do
 		case ${need} in
 			*ME*)
-				Extract_me || _failed="${_failed} me"
+				Download_me || _failed="${_failed} me"
 				;;
 			*MRC*)
 				./download mrc || _failed="${_failed} mrc"
@@ -102,40 +102,61 @@ Download_needed(){
 	fi
 }
 
-Extract_me(){
+Download_me() {
+	printf "Downloading neutered ME for board: `%s`\n" ${board}
+
+	Fetch_update || return 1
+	Extract_me || return 1
+
+	return 0
+}
+
+Fetch_update() {
+	printf "Fetching vendor update for board: `%s`\n" ${board}
+
 	_me_destination=${CONFIG_ME_BIN_PATH#../../}
 
-	if [ -f "${_me_destination}" ]; then
-		printf 'me already downloaded\n'
-		return 0
-	fi
-
 	if [ -z "${dl_url+x}" ]; then
-		printf 'no me download available for this board\n'
+		printf "No vendor update specified for board: `%s`\n" ${board}
 		return 1
 	fi
 
+	Vendor_checksum blobs/me.exe || \
+		curl ${dl_url} > blobs/me.exe || curl ${dl_url_bkup} > blobs/me.exe
+
+	Vendor_checksum blobs/me.exe || Fail \
+		"Cannot guarantee intergity of vendor update for board: `${board}`"
+
+	return 0
+}
+
+Vendor_checksum() {
+	if [ ! -f "blobs/me.exe" ]; then
+		printf "Vendor update not found on disk for board: `%s`\n" ${board}
+		return 1
+	fi
+	if [ "$(sha1sum blobs/me.exe | awk '{print $1}')" != "${dl_hash}" ]; then
+		printf "Bad checksum on vendor update for board: `%s`\n" ${board}
+		rm blobs/me.exe
+		return 1
+	fi
+	return 0
+}
+
+Extract_me(){
+	printf "Extracting neutered ME for ${board}\n"
+
 	if [ ! -d "${_me_destination%/*}" ]; then
 		mkdir -p ${_me_destination%/*}
 	fi
-
-	printf "Extracting neutered me for ${board}\n"
 	
-	# Delete old me downloads in case user is building for multiple boards
-	if [ -f "blobs/me.exe" ]; then
-		rm blobs/me.exe
-	fi
-
 	if [ -d "blobs/app" ]; then
 		rm -r blobs/app
 	fi
 
-	curl ${dl_url} > blobs/me.exe || curl ${dl_url_bkup} > blobs/me.exe
+	if [ -f "${_me_destination}" ]; then
-
+		printf 'me already downloaded\n'
-	if [ "$(sha1sum blobs/me.exe | awk '{print $1}')" != "${dl_hash}" ]; then
+		return 0
-		printf 'checksum of downloaded me did not mactch\ncorrupted me downloaded or wrong me for board\n'
-		rm blobs/me.exe
-		return 1
 	fi
 
 	printf 'extracting and stripping intel management engine\n'