Re: [Qemu-devel] [PATCH 1/2] qemu-nbd: Shrink image size by specified offset

[Eric Blake]

On 09/20/2016 04:37 AM, Tomáš Golembiovský wrote:

[meta-comment]: Your series came through without any threading (you sent
three threads, instead of patch 1 and 2 being marked In-Reply-To the 0/2
cover letter).

> When --offset is set the apparent device size has to be adjusted
> accordingly. Otherwise client may request read/write beyond the file end
> which would fail.
> 
> Signed-off-by: Tomáš Golembiovský <address@hidden>
> ---
>  qemu-nbd.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index 99297a5..629bce1 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -901,6 +901,13 @@ int main(int argc, char **argv)
>          exit(EXIT_FAILURE);
>      }

Additional context:

    off_t dev_offset = 0;

    off_t fd_size;

>  
> +    if (dev_offset >= fd_size) {
> +        error_report("Offset (%lu) has to be smaller than the image size 
> (%lu)",
> +                     dev_offset, fd_size);

Whoops, this fails to compile on 32-bit platforms.  %lu is not
necessarily synonymous with off_t values.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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