[libvirt-users] Does libvirt have API to detect image format

[Jianfeng Tang]

Unfortunately my backing store file is not in a volume. So I guess I
cannot use that method.

On 8/11/14 3:45 PM, "Eric Blake" <eblake at redhat.com> wrote:

>On 08/11/2014 02:35 PM, Jianfeng Tang wrote:
>>>
>> 
>> I am using backing store when I create my volume. However, the backing
>> store file is from another team, which can be either in raw or in qcow2
>> format.
>> 
>> Is there a libvirt API to detect image format by given an image file?
>>Or I
>> have to run qemu-img?
>
>virStorageVolGetXMLDesc() in the C code ('virsh vol-dumpxml' from the
>command line), if your volume resides within a storage pool.
>Furthermore, if there is ANY possibility that the file might be raw but
>that the volume has been in use by a possibly malicious guest, you
>CANNOT blindly trust a file probe that says qcow2, because a guest can
>write header information into a raw disk in order to make probes return
>qcow2.  So take the output with a grain of salt (it is safe to blindly
>trust a claim of 'raw', but blindly trusting a claim of 'qcow2' is risky
>if you don't know the history behind the image).
>
>-- 
>Eric Blake   eblake redhat com    +1-919-301-3266
>Libvirt virtualization library http://libvirt.org
>