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authorAvi Kivity <avi@redhat.com>2010-11-16 16:33:17 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2010-11-21 09:16:57 -0600
commit33bbd1de5ec9b8802d63e811908f2351ba83884c (patch)
tree83a5c677c69dd0da3ee94732b5ee4920743aaf7d /pc-bios
parente71e00ed258202052570ae631536f4d7b65792fa (diff)
optionrom: fix bugs in signrom.sh
signrom.sh has multiple bugs: - the last byte is considered when calculating the existing checksum, but not when computing the correction - apprently the 'expr' expression overflows and produces incorrect results with larger roms - if the checksum happened to be zero, we calculated the correction byte to be 256 Instead of rewriting this in half a line of python, this patch fixes the bugs. Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'pc-bios')
-rwxr-xr-xpc-bios/optionrom/signrom.sh7
1 files changed, 3 insertions, 4 deletions
diff --git a/pc-bios/optionrom/signrom.sh b/pc-bios/optionrom/signrom.sh
index 975b27dd6..9dc5c63dd 100755
--- a/pc-bios/optionrom/signrom.sh
+++ b/pc-bios/optionrom/signrom.sh
@@ -31,14 +31,13 @@ x=`dd if="$1" bs=1 count=1 skip=2 2>/dev/null | od -t u1 -A n`
size=$(( $x * 512 - 1 ))
# now get the checksum
-nums=`od -A n -t u1 -v "$1"`
+nums=`od -A n -t u1 -v -N $size "$1"`
for i in ${nums}; do
# add each byte's value to sum
- sum=`expr $sum + $i`
+ sum=`expr \( $sum + $i \) % 256`
done
-sum=$(( $sum % 256 ))
-sum=$(( 256 - $sum ))
+sum=$(( (256 - $sum) % 256 ))
sum_octal=$( printf "%o" $sum )
# and write the output file