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author | Avi Kivity <avi@redhat.com> | 2010-11-16 16:33:17 +0200 |
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committer | Anthony Liguori <aliguori@us.ibm.com> | 2010-11-21 09:16:57 -0600 |
commit | 33bbd1de5ec9b8802d63e811908f2351ba83884c (patch) | |
tree | 83a5c677c69dd0da3ee94732b5ee4920743aaf7d /pc-bios | |
parent | e71e00ed258202052570ae631536f4d7b65792fa (diff) | |
download | qemu-33bbd1de5ec9b8802d63e811908f2351ba83884c.zip qemu-33bbd1de5ec9b8802d63e811908f2351ba83884c.tar.gz qemu-33bbd1de5ec9b8802d63e811908f2351ba83884c.tar.bz2 |
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-x | pc-bios/optionrom/signrom.sh | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/pc-bios/optionrom/signrom.sh b/pc-bios/optionrom/signrom.sh index 975b27d..9dc5c63 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 |