Re: [Libguestfs] Checksums and other verification
On Mon, Feb 27, 2023 at 3:56 PM Richard W.M. Jones <rjones(a)redhat.com> wrote:
https://github.com/kubevirt/containerized-data-importer/issues/1520
Hi Eric,
We had a question from the Kubevirt team related to the above issue.
The question is roughly if it's possible to calculate the checksum of
an image as an nbdkit filter and/or in the qemu block layer.
Supplemental #1: could qemu-img convert calculate a checksum as it goes
along?
Supplemental #2: could we detect various sorts of common errors, such
a webserver that is incorrectly configured and serves up an error page
containing "<html>"; or something which is supposed to be a disk image
but does not "look like" (in some ill-defined sense) a disk image,
eg. it has no partition table.
I'm not sure if qemu has any existing features covering the above (and
I know for sure that nbdkit doesn't).
One issue is that calculating a checksum involves a linear scan of the
image, although we can at least skip holes.
Kubvirt can use blksum
https://fosdem.org/2023/schedule/event/vai_blkhash_fast_disk/
But we need to package it for Fedora/CentOS Stream.
I also work on "qemu-img checksum", getting more reviews on this can help:
Lastest version:
https://lists.nongnu.org/archive/html/qemu-block/2022-11/msg00971.html
Last reveiw are here:
https://lists.nongnu.org/archive/html/qemu-block/2022-12/
More work is needed on the testing framework changes.
Nir