implement in-place update [WIP]

WIP: /system/etc/hosts might be filesystem-writable but the enclosing filesystem itself might not be mounted writable

.shellcheckrc

@@ -20,3 +20,7 @@ disable=SC2004
 
 # redundant sed invocation
 disable=SC2001
+
+# referencing unassigned variable
+#  we need to reference magisk pre-set variables a lot
+disable=SC2154

magiskmodule/customize.sh

@@ -0,0 +1,20 @@
+#!/system/bin/sh
+
+exec 2>&1
+
+[ "$BOOTMODE" != "true" ] && abort "Please install this module within the Magisk app."
+
+# path to already installed module
+INSTALLEDMODPATH=/data/adb/modules/MagicalProtection
+
+[ ! -d "$INSTALLEDMODPATH" ] && return 0
+[ ! -w /system/etc/hosts ] && return 0
+
+ui_print "- Performing in-place update"
+
+cp -v -r -f "$MODPATH"/* "$INSTALLEDMODPATH"
+cp -v -f "$MODPATH"/system/etc/hosts /system/etc/hosts
+
+rm -v -r "$MODPATH"
+
+exit 0