[Qemu-devel] Re: [PATCH] Fix checksum writing in signboot.sh

[Avi Kivity <avi@redhat.com>]

On 08/01/2009 12:48 PM, Alexander Graf wrote:
> The printf command takes an octal value after \, so we have to convert
> our decimal representation to octal first and then write it.
>
> This unbreaks extboot signing. Multiboot wasn't affected yet because
> the checksum was<  8.
>
> Spotted and first patch by Glauber Costa<glommer@redhat.com>.
> Printf idea by Paolo Bonzini<bonzini@gnu.org>.
>
> Signed-off-by: Alexander Graf<agraf@suse.de>
> CC: Glauber Costa<glommer@redhat.com>
> CC: Paolo Bonzini<bonzini@gnu.org>
> CC: Jan Ondrej<ondrejj@salstar.sk>
> ---
>   pc-bios/optionrom/signrom.sh |    3 ++-
>   1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/pc-bios/optionrom/signrom.sh b/pc-bios/optionrom/signrom.sh
> index 4322811..975b27d 100755
> --- a/pc-bios/optionrom/signrom.sh
> +++ b/pc-bios/optionrom/signrom.sh
> @@ -39,7 +39,8 @@ done
>
>   sum=$(( $sum % 256 ))
>   sum=$(( 256 - $sum ))
> +sum_octal=$( printf "%o" $sum )
>
>   # and write the output file
>   cp "$1" "$2"
> -printf "\\$sum" | dd of="$2" bs=1 count=1 seek=$size conv=notrunc 2>/dev/null
> +printf "\\$sum_octal" | dd of="$2" bs=1 count=1 seek=$size conv=notrunc 2>/dev/null
>    

While the patch is good, the code is unreadable.  Can we mandate python 
for such tricks?

    f = file(out, 'r+b')
    f.seek(size)
    f.write(chr(sum))

sh is not a sane programming language.

-- 
error compiling committee.c: too many arguments to function