[Buildroot] [PATCH] package/initscripts: refactor S20urandom
unixmania at gmail.com
unixmania at gmail.com
Wed Oct 23 16:46:05 UTC 2019
From: Carlos Santos <unixmania at gmail.com>
Adapt the format to the current template, used in other init scripts.
Read /proc/sys/kernel/random/poolsize to calculate the pool size, as
suggestred by the urandom manual page.
Save the seed at /var/lib/ as other non-systemd distributions do (e.g.
RHEL6), since /etc can be in a red-only filesystem and the Filesystem
Hierarchy Standard defines that /var/lib holds persistent data modified
by programs as they run.
Users willing to use a different path just need to redefine URANDOM_SEED
in /etc/default/urandom instead of rewriting the init script.
Signed-off-by: Carlos Santos <unixmania at gmail.com>
---
package/initscripts/init.d/S20urandom | 105 ++++++++++++++++----------
1 file changed, 64 insertions(+), 41 deletions(-)
diff --git a/package/initscripts/init.d/S20urandom b/package/initscripts/init.d/S20urandom
index cababe1023..94e46cff10 100644
--- a/package/initscripts/init.d/S20urandom
+++ b/package/initscripts/init.d/S20urandom
@@ -1,51 +1,74 @@
#! /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 at cistron.nl
+# Save the random seed between reboots. See urandom(4).
#
+# Quietly do nothing if /dev/urandom does not exist
[ -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
- [ "$VERBOSE" != no ] && echo "done."
- ;;
- stop)
- if ! touch /etc/random-seed 2>/dev/null
- then
- exit
+URANDOM_SEED="/var/lib/random-seed"
+
+# shellcheck source=/dev/null
+[ -r "/etc/default/urandom" ] && . "/etc/default/urandom"
+
+pool_size_file="/proc/sys/kernel/random/poolsize"
+
+start() {
+ # Carry a random seed from start-up to start-up
+ # Load and then save the whole entropy pool
+ printf 'Initializing random number generator: '
+ if [ -f "$URANDOM_SEED" ]; then
+ dd if="$URANDOM_SEED" of=/dev/urandom status=none
+ status=$?
+ if [ "$status" -ne 0 ]; then
+ echo "FAIL (can't dump $URANDOM_SEED to /dev/urandom)"
+ return "$status"
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."
- ;;
+ fi
+ if bits=$(cat "$pool_size_file" 2> /dev/null); then
+ bytes=$((bits/8))
+ else
+ bytes=512
+ fi
+ umask 077
+ dd if=/dev/urandom of="$URANDOM_SEED" bs="$bytes" count=1 status=none
+ status=$?
+ umask 022
+ if [ "$status" -eq 0 ]; then
+ echo "OK"
+ else
+ echo "FAIL"
+ fi
+ return "$status"
+}
+
+stop() {
+ # Carry a random seed from shut-down to start-up
+ # Save the whole entropy pool
+ printf "Saving random seed: "
+ if bits=$(cat "$pool_size_file" 2> /dev/null); then
+ bytes=$((bits/8))
+ else
+ bytes=512
+ fi
+ umask 077
+ dd if=/dev/urandom of="$URANDOM_SEED" bs="$bytes" count=1 status=none
+ status=$?
+ umask 022
+ if [ "$status" -eq 0 ]; then
+ echo "OK"
+ else
+ echo "FAIL"
+ fi
+ return "$status"
+}
+
+case "$1" in
+ start|stop)
+ "$1";;
+ restart|reload)
+ :;;
*)
- echo "Usage: urandom {start|stop}" >&2
+ echo "Usage: $0 {start|stop|restart|reload}"
exit 1
- ;;
esac
--
2.18.1
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