initramfs: introduced `resume` script, to check and trigger a `switch_root` if viable

initramfs/sbin_resume.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+# --- SDE-COPYRIGHT-NOTE-BEGIN ---
+# This copyright note is auto-generated by ./scripts/Create-CopyPatch.
+#
+# Filename: target/idunn/initramfs/sbin_resume.sh
+# Copyright (C) 2008 The OpenSDE Project
+#
+# More information can be found in the files COPYING and README.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License. A copy of the
+# GNU General Public License can be found in the file COPYING.
+# --- SDE-COPYRIGHT-NOTE-END ---
+
+# just once!
+LOCK=/var/run/init.lock
+ln -s / $LOCK 2> /dev/null || return
+
+if /etc/rc.d/rc.trymount; then
+	# rootfs mounted
+	. /etc/rc.d/functions.in
+	. /etc/conf/idunn
+
+	if ! grep -q "^[^ ]* $rootfs [^ ]* $root_mode[, ]" /proc/mounts; then
+		title "Remouting $rootfs as $root_mode"
+		check mount -o remount,$root_mode "$rootfs"
+		status
+	fi
+
+	title "Checking for init ($init)"
+	if [ -n "$init" -a -x "$rootfs$init" ]; then
+		check touch /var/run/.idunn-resume
+	else
+		check false
+	fi
+	status
+else
+	error=1
+fi
+
+rm -f $LOCK
+exit $error