improved A/B device support code taken from Magisk 16.6

ChangeLog.md

@@ -16,6 +16,8 @@
      * more information below
   * by default install Déjà Vu and Mozilla nlp Backends
   * improve GApps uninstallation routine
+* CommonInstaller
+  * improved A/B device support code taken from Magisk 16.6
 
 ### Updates
 

CommonInstaller

@@ -81,6 +81,12 @@ grep_prop() {
 		head -n 1
 }
 
+grep_cmdline() {
+	local REGEX="s/^${1}=//p"
+	sed -E 's/ +/\n/g' /proc/cmdline | \
+		sed -n "${REGEX}" 2>/dev/null
+}
+
 is_mounted() {
 	if [ ! -z "${2}" ]; then
 		cat /proc/mounts | grep ${1} | grep ${2}, >/dev/null
@@ -180,9 +186,9 @@ error () {
 
 # taken from Magisk, with minor modifications for NanoDroid
 mount_partitions () {
-	SLOT=$(getprop ro.boot.slot_suffix)
+	SLOT=$(grep_cmdline androidboot.slot_suffix)
 	if [ -z ${SLOT} ]; then
-		SLOT=$(getprop ro.boot.slot)
+		SLOT=$(grep_cmdline androidboot.slot)
 		[ "${SLOT}" = "_" ] && SLOT=
 	fi
 
@@ -197,13 +203,13 @@ mount_partitions () {
 		mount -t ext4 -o rw $SYSTEMBLOCK /system
 	fi
 
-	if [ -f /system/init.rc ]; then
+	[ ! -f /system/build.prop ] && error "failed to mount /system (unsupported A/B device?)"
+
+	if [ -f /system/init ]; then
 		mkdir /system_root 2>/dev/null
 		mount --move /system /system_root
 		mount -o bind /system_root/system /system
 	fi
-
-	[ ! -f /system/build.prop ] && error "failed to mount /system"
 }
 
 detect_mode () {