openrc/init.d/urandom

#!/sbin/runscript
# Copyright 1999-2007 Gentoo Foundation
# Copyright 2007 Roy Marples
# All rights reserved

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
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#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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urandom_seed=${urandom_seed:-${URANDOM_SEED:-/var/run/random-seed}}

description="Initializes the random number generator."

depend() {
	need localmount
}

save_seed() {
	local poolsize=1

	if [ -e /proc/sys/kernel/random/poolsize ] ; then
		poolsize=$(($(cat /proc/sys/kernel/random/poolsize) / 4096))
	fi

	(	# sub shell to prevent umask pollution
		umask 077
		dd if=/dev/urandom of="${urandom_seed}" count=${poolsize} 2>/dev/null
	)
}

start() {
	[ -c /dev/urandom ] || return
	if [ -f "${urandom_seed}" ] ; then
		ebegin "Initializing random number generator"
		cat "${urandom_seed}" > /dev/urandom
		eend $? "Error initializing random number generator"
	fi
	rm -f "${urandom_seed}" && save_seed
	return 0
}

stop() {
	ebegin "Saving random seed"
	# Carry a random seed from shut-down to start-up;
	# see documentation in linux/drivers/char/random.c
	save_seed
	eend $? "Failed to save random seed"
}

# vim: set ts=4 :