package sysfsutils: add support for sysfs settings at boot

This patch is based on sysfsutils package's behaviour on Debian OS.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>

package/libs/sysfsutils/files/sysfsutils

@@ -0,0 +1,48 @@
+#!/bin/sh /etc/rc.common
+# Copyright (C) 2017 Rodolfo Giometti <giometti@enneenne.com>
+#
+# Based on Debian's script /etc/init.d/sysfsutils by
+# Martin Pitt <mpitt@debian.org>
+
+load_conffile() {
+	FILE="$1"
+	sed  's/#.*$//; /^[[:space:]]*$/d;
+	  s/^[[:space:]]*\([^=[:space:]]*\)[[:space:]]*\([^=[:space:]]*\)[[:space:]]*=[[:space:]]*\(.*\)/\1 \2 \3/' \
+	  $FILE | {
+	while read f1 f2 f3; do
+		if [ "$f1" = "mode" -a -n "$f2" -a -n "$f3" ]; then
+			if [ -f "/sys/$f2" ] || [ -d "/sys/$f2" ]; then
+				chmod "$f3" "/sys/$f2"
+			else
+				echo "unknown attribute $f2"
+			fi
+		elif [ "$f1" = "owner" -a -n "$f2" -a -n "$f3" ]; then
+			if [ -f "/sys/$f2" ]; then
+				chown "$f3" "/sys/$f2"
+			else
+				echo "unknown attribute $f2"
+			fi
+		elif [ "$f1" -a -n "$f2" -a -z "$f3" ]; then
+			if [ -f "/sys/$f1" ]; then
+				# Some fields need a terminating newline, others
+				# need the terminating newline to be absent :-(
+				echo -n "$f2" > "/sys/$f1" 2>/dev/null ||
+					echo "$f2" > "/sys/$f1"
+			else
+				echo "unknown attribute $f1"
+			fi
+		else
+			echo "syntax error in $CONFFILE: '$f1' '$f2' '$f3'"
+			exit 1
+		fi
+	done
+	}
+}
+
+START=11
+start() {
+	for file in /etc/sysfs.conf /etc/sysfs.d/*.conf; do
+		[ -r "$file" ] || continue
+		load_conffile "$file"
+	done
+}