buildroot

#! /bin/sh

#

# urandom   This script saves the random seed between reboots.

#       It is called from the boot, halt and reboot scripts.

#

# Version:  @(#)urandom  1.33  22-Jun-1998  miquels@cistron.nl

#

​

[ -c /dev/urandom ] || exit 0

#. /etc/default/rcS

​

case "$1" in

    start|"")

        # check for read only file system

        if ! touch /etc/random-seed 2>/dev/null

        then

            echo "read-only file system detected...done"

            exit

        fi

        if [ "$VERBOSE" != no ]

        then

            printf "Initializing random number generator... "

        fi

        # Load and then save 512 bytes,

        # which is the size of the entropy pool

        cat /etc/random-seed >/dev/urandom

        rm -f /etc/random-seed

        umask 077

        dd if=/dev/urandom of=/etc/random-seed count=1 \

            >/dev/null 2>&1 || echo "urandom start: failed."

        umask 022

        [ "$VERBOSE" != no ] && echo "done."

        ;;

    stop)

        if ! touch /etc/random-seed 2>/dev/null

                then

                        exit

                fi

        # Carry a random seed from shut-down to start-up;

        # see documentation in linux/drivers/char/random.c

        [ "$VERBOSE" != no ] && printf "Saving random seed... "

        umask 077

        dd if=/dev/urandom of=/etc/random-seed count=1 \

            >/dev/null 2>&1 || echo "urandom stop: failed."

        [ "$VERBOSE" != no ] && echo "done."

        ;;

    *)

        echo "Usage: urandom {start|stop}" >&2

        exit 1

        ;;

esac