#!/bin/sh
#
# Copyright (c) 2001-2006,2012 Douglas Barton, dougb@FreeBSD.org
# 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
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD: stable/11/libexec/save-entropy/save-entropy.sh 273872 2014-10-30 21:21:53Z markm $

# This script is called by cron to store bits of randomness which are
# then used to seed /dev/random on boot.

# Originally developed by Doug Barton, dougb@FreeBSD.org

setglobal PATH = '/bin:/usr/bin'

# If there is a global system configuration file, suck it in.
#
if test -r /etc/defaults/rc.conf {
	source /etc/defaults/rc.conf
	source_rc_confs 2>/dev/null
} elif test -r /etc/rc.conf {
	source /etc/rc.conf 2>/dev/null
}

test $[/sbin/sysctl -n security.jail.jailed] = 0 || exit 0

match $(entropy_dir) {
with [Nn][Oo]
	exit 0
	
with *
	setglobal entropy_dir = $(entropy_dir:-/var/db/entropy)
	
}

setglobal entropy_save_sz = $(entropy_save_sz:-4096)
setglobal entropy_save_num = $(entropy_save_num:-8)

if test ! -d $(entropy_dir) {
	install -d -o operator -g operator -m 0700 $(entropy_dir) || do {
		logger -is -t $0 The entropy directory $(entropy_dir) does \
		    not exist, and cannot be created. Therefore no entropy can \
		    be saved.; exit 1; }
}

cd $(entropy_dir) || do {
	logger -is -t $0 Cannot cd to the entropy directory: "$(entropy_dir)". \
	    Entropy file rotation is aborted.; exit 1; }

for f in [saved-entropy.*] {
	match $(f) { with saved-entropy.\* continue  }	# No files match
	test $(f#saved-entropy\.) -ge $(entropy_save_num) && unlink $(f)
}

umask 377

setglobal n = $shExpr(' ${entropy_save_num} - 1 ')
while test $(n) -ge 1 {
	if test -f "saved-entropy.$(n)" {
		mv "saved-entropy.$(n)" "saved-entropy.$shExpr(' ${n} + 1 ')"
	} elif test -e "saved-entropy.$(n)" -o -L "saved-entropy.$(n)" {
		logger -is -t $0 \
	"$(entropy_dir)/saved-entropy.$(n)" is not a regular file, and so \
	    it will not be rotated. Entropy file rotation is aborted.
		exit 1
	}
	setglobal n = $shExpr(' ${n} - 1 ')
}

dd if=/dev/random of=saved-entropy.1 bs=$(entropy_save_sz) count=1 2>/dev/null

exit 0