Re: [Qemu-devel] [PATCH] qemu-img: refuse to compress files with invalid size

["Benoît Canet" <benoit.canet@irqsave.net>]

Le Friday 12 Apr 2013 à 19:37:48 (+0200), Stefan Hajnoczi a écrit :
> Image file compression works at cluster granularity.  It is not possible
> to compress less than a cluster of data at a time.
> 
> Print an error when attempting qemu-img convert -c with an input file
> that is not a multiple of the cluster size.
> 
> I considered automatically adjusting the output file size but think it's
> better to be explicit.  This avoids confusion when users notice that
> image file size changed after conversion.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  qemu-img.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/qemu-img.c b/qemu-img.c
> index 31627b0..2273851 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1370,6 +1370,13 @@ static int img_convert(int argc, char **argv)
>              goto out;
>          }
>          cluster_sectors = cluster_size >> 9;
> +        if (total_sectors % cluster_sectors) {
> +            error_report("compression requires that input file size is a "
> +                         "multiple of %d bytes",
> +                         cluster_size);
> +            ret = -1;
> +            goto out;
> +        }
>          sector_num = 0;
>  
>          nb_sectors = total_sectors;
> -- 
> 1.8.1.4
> 
> 
Reviewed-by: Benoit Canet <benoit@irqsave.net>