cirros-testvm/src-cirros/buildroot-2015.05/system/skeleton/etc/init.d/S20urandom

   1 #! /bin/sh
   2 #
   3 # urandom       This script saves the random seed between reboots.
   4 #               It is called from the boot, halt and reboot scripts.
   5 #
   6 # Version:      @(#)urandom  1.33  22-Jun-1998  miquels@cistron.nl
   7 #
   8
   9 [ -c /dev/urandom ] || exit 0
  10 #. /etc/default/rcS
  11
  12 case "$1" in
  13         start|"")
  14                 if [ "$VERBOSE" != no ]
  15                 then
  16                         echo -n "Initializing random number generator... "
  17                 fi
  18                 # Load and then save 512 bytes,
  19                 # which is the size of the entropy pool
  20                 if [ -f /etc/random-seed ]
  21                 then
  22                         cat /etc/random-seed >/dev/urandom
  23                 fi
  24                 # check for read only file system
  25                 if ! touch /etc/random-seed 2>/dev/null
  26                 then
  27                         echo "read-only file system detected...done"
  28                         exit
  29                 fi
  30                 rm -f /etc/random-seed
  31                 umask 077
  32                 dd if=/dev/urandom of=/etc/random-seed count=1 \
  33                         >/dev/null 2>&1 || echo "urandom start: failed."
  34                 umask 022
  35                 [ "$VERBOSE" != no ] && echo "done."
  36                 ;;
  37         stop)
  38                 if ! touch /etc/random-seed 2>/dev/null
  39                 then
  40                         exit
  41                 fi
  42                 # Carry a random seed from shut-down to start-up;
  43                 # see documentation in linux/drivers/char/random.c
  44                 [ "$VERBOSE" != no ] && echo -n "Saving random seed... "
  45                 umask 077
  46                 dd if=/dev/urandom of=/etc/random-seed count=1 \
  47                         >/dev/null 2>&1 || echo "urandom stop: failed."
  48                 [ "$VERBOSE" != no ] && echo "done."
  49                 ;;
  50         *)
  51                 echo "Usage: urandom {start|stop}" >&2
  52                 exit 1
  53                 ;;
  54 esac