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Re: [libvirt] [PATCH] Add basic support for VDI images



On 02/04/2013 04:53 PM, Daniel P. Berrange wrote:
> On Mon, Feb 04, 2013 at 04:46:53PM +0100, Martin Kletzander wrote:
[...]
>> +
>> +    /* not fully supported, but qemu knows it, so we should be able to
>> +     * handle this at least basically */
>> +    [VIR_STORAGE_FILE_VDI] = { NULL, ".vdi", LV_LITTLE_ENDIAN,
>> +                               -2, 0, 0, 0, 0, -1, NULL},
> 
> We can do better than that - look at block/vdi.c in QEMU GIT tree
> to find out the offsets / values for version number, magic signature
> at least, even if you ignore backing files for now.
> 

Thanks for pointing that out, I've got a v2 and will send it
after some testing.  However, it looks like VDI doesn't have a
magic, because there is a 40 Byte string at the start that cacn
contain anything the creating binary puts there.  For example
qemu-img uses "<<< QEMU VM Virtual Disk Image >>>\n".  According
to [1], I'm adding "<<<" as the magic, because we don't fail if
it doesn't match and we can still match it by the extension then.

[1] Cite from block/vdi.c:

/* Innotek / SUN images use these strings in header.text:
 * "<<< innotek VirtualBox Disk Image >>>\n"
 * "<<< Sun xVM VirtualBox Disk Image >>>\n"
 * "<<< Sun VirtualBox Disk Image >>>\n"
 * The value does not matter, so QEMU created images use a different text.
 */
#define VDI_TEXT "<<< QEMU VM Virtual Disk Image >>>\n"

I added all the rest I could, though.

Martin


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