Re: [Libguestfs] Checksums and other verification
On Mon, Feb 27, 2023 at 07:09:33PM +0200, Nir Soffer wrote:
On Mon, Feb 27, 2023 at 6:41 PM Richard W.M. Jones
<rjones(a)redhat.com> wrote:
> I think it would be more useful if (or in addition) it could compute
> the checksum of a stream which is being converted with 'qemu-img
> convert'. Extra points if it can compute the checksum over either the
> input or output stream.
I thought about this, it could be a filter that you add in the graph
that gives you checksum as a side effect of copying. But this requires
disabling unordered writes, which is pretty bad for performance.
But even if you compute the checksum during a transfer, you want to
verify it by reading the transferred data from storage. Once you computed
the checksum you can keep it for verifying the same image in the future.
The use-case I have in mind is being able to verify a download when
you already know the checksum and are copying / converting the image
in flight.
eg: You are asked to download https://example.com/distro-cloud.qcow2
with some published checksum and you will on the fly download and
convert this to raw, but want to verify the checksum (of the qcow2)
during the conversion step. (Or at some point, but during the convert
avoids having to spool the image locally.)
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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