From 7cdf3708f075af5d21e397c6f1b59adab48ac730 Mon Sep 17 00:00:00 2001 From: Jan-Philipp Litza Date: Sun, 19 Jan 2014 16:43:25 +0100 Subject: [PATCH] gluon-autoupdater: get random number from urandom The approach with awk's rand() wasn't really random between across devices: When srand() was called without arguments, time() was used as seed, which of course is the same on all devices when the script is called via cron at HH:00:00. This patch instead uses /dev/urandom as source of random (we don't need cryptographically strong random numbers, so urandom is just fine) but still uses awk for the comparison as busybox's ash cannot deal with floats in $(()) --- package/gluon-autoupdater/files/usr/sbin/autoupdater | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/package/gluon-autoupdater/files/usr/sbin/autoupdater b/package/gluon-autoupdater/files/usr/sbin/autoupdater index bdd23245..c18e27fc 100755 --- a/package/gluon-autoupdater/files/usr/sbin/autoupdater +++ b/package/gluon-autoupdater/files/usr/sbin/autoupdater @@ -10,7 +10,9 @@ BRANCH=$(uci get autoupdater.settings.branch) PROBABILITY=$(uci get autoupdater.${BRANCH}.probability) if test "a$1" != "a-f"; then - echo | awk "END{srand();exit rand() > $PROBABILITY}" + # get one random byte from /dev/urandom, convert it to decimal and check + # against update_probability*255 + hexdump -n1 -e '/1 "%d"' /dev/urandom | awk "{exit \$1 > $PROBABILITY * 255}" if test $? -ne 0; then echo "No autoupdate this time. Use -f to override" exit 0