Update update-binary

fixed Magisk-Modules-Repo#12

META-INF/com/google/android/update-binary

@@ -1,10 +1,33 @@
 #!/sbin/sh
-# This is a dummy file that should be replaced with a proper installer script
-
-# If you are creating a module locally for personal usage or testing,
-# download the script in the following URL:
-# https://github.com/topjohnwu/Magisk/blob/master/scripts/module_installer.sh
-# And replace this script with the downloaded script
-
-# Error, this script should always be replaced
-exit 1
+
+#################
+# Initialization
+#################
+
+umask 022
+
+# echo before loading util_functions
+ui_print() { echo "$1"; }
+
+require_new_magisk() {
+  ui_print "*******************************"
+  ui_print " Please install Magisk v20.4+! "
+  ui_print "*******************************"
+  exit 1
+}
+
+#########################
+# Load util_functions.sh
+#########################
+
+OUTFD=$2
+ZIPFILE=$3
+
+mount /data 2>/dev/null
+
+[ -f /data/adb/magisk/util_functions.sh ] || require_new_magisk
+. /data/adb/magisk/util_functions.sh
+[ $MAGISK_VER_CODE -lt 20400 ] && require_new_magisk
+
+install_module
+exit 0