diff options
| author | Theo Buehler <tb@cvs.openbsd.org> | 2017-06-26 17:00:50 +0000 |
|---|---|---|
| committer | Theo Buehler <tb@cvs.openbsd.org> | 2017-06-26 17:00:50 +0000 |
| commit | 3157a1a45f170e0791a64272357e0bec53c69ea2 (patch) | |
| tree | ea9a06e75f94ade163ae9261ae668e09b932b0a3 /sys | |
| parent | 0dfd3caccbbea4c9aa8c02e6fbc8157078ab2cba (diff) | |
RANDOM1 was subject to rather bad modulus bias. Improve the situation a bit
by implementing an arc4random_uniform(3) clone with beloved jot(1) and
using it.
discussed with and ok deraadt
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/conf/makegap.sh | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/sys/conf/makegap.sh b/sys/conf/makegap.sh index ddf16ffe7e6..e104163fb48 100644 --- a/sys/conf/makegap.sh +++ b/sys/conf/makegap.sh @@ -1,16 +1,28 @@ #!/bin/sh - +random_uniform() { + local _upper_bound + + if [[ $1 -gt 0 ]]; then + _upper_bound=$(($1 - 1)) + else + _upper_bound=0 + fi + + echo `jot -r 1 0 $_upper_bound 2>/dev/null` +} + umask 007 PAGE_SIZE=`sysctl -n hw.pagesize` PAD=$1 GAPDUMMY=$2 -RANDOM1=$((RANDOM % (3 * PAGE_SIZE))) -RANDOM2=$((RANDOM % PAGE_SIZE)) -RANDOM3=$((RANDOM % PAGE_SIZE)) -RANDOM4=$((RANDOM % PAGE_SIZE)) -RANDOM5=$((RANDOM % PAGE_SIZE)) +RANDOM1=`random_uniform $((3 * PAGE_SIZE))` +RANDOM2=`random_uniform $PAGE_SIZE` +RANDOM3=`random_uniform $PAGE_SIZE` +RANDOM4=`random_uniform $PAGE_SIZE` +RANDOM5=`random_uniform $PAGE_SIZE` cat > gap.link << __EOF__ |