Re: [Qemu-devel] [PATCH v2 07/12] block/dmg: set virtual size to a non-zero value

[John Snow <jsnow@redhat.com>]

On 01/06/2015 12:48 PM, Peter Wu wrote:
> Right now the virtual size is always reported as zero which makes it
> impossible to convert between formats.
>
> After this patch, the number of sectors will be read from the trailer
> ("koly" block).
>
> To verify the behavior, the output of `dmg2img foo.dmg foo.img` was
> compared against `qemu-img convert -f dmg -O raw foo.dmg foo.raw`. The
> tests showed that the file contents are exactly the same, except that
> QEMU creates a slightly larger file (it matches the total sectors
> count).
>
> Signed-off-by: Peter Wu <peter@lekensteyn.nl>
> ---
>   v2: fixed typo in commit message (s/mish/koly/)
> ---
>   block/dmg.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/block/dmg.c b/block/dmg.c
> index 1a0fa0e..57feb1b 100644
> --- a/block/dmg.c
> +++ b/block/dmg.c
> @@ -453,6 +453,14 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
>           ret = -EINVAL;
>           goto fail;
>       }
> +    ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +    if (bs->total_sectors < 0) {
> +        ret = -EINVAL;
> +        goto fail;
> +    }
>       if (rsrc_fork_length != 0) {
>           ret = dmg_read_resource_fork(bs, &ds,
>                                        rsrc_fork_offset, rsrc_fork_length);
>

You may want to adjust the commit message here to reflect the 
information in your new cover letter regarding the bug in dmg2img, but 
that's not worth re-spinning for.

Reviewed-by: John Snow <jsnow@redhat.com>