[libvirt] [PATCH 1/3] utils: Implement virCommandPassFDGetFDIndex

[Eric Blake]

On 02/24/2015 09:52 PM, Martin Kletzander wrote:

>> The problem of having to prevent the reordering of file descriptors
>> when we are building the QEMU command line with file descriptors
>> already exists today. So maybe I could just remove this flag and the
>> related check knowing that reordering of file descriptors and building
>> the QEMU command line that contains file descriptor (from before the
>> order) would not be allowed today without any of the patches I am
>> trying to add.
>>
> 
> You surely and safely can.  The point behind reordering FDs was that
> when you're using FD passing as done by systemd, those FDs passed must
> start from number 3.  However, because we are already passing a bunch
> of file descriptors to QEMU and other commands, we *must not* reorder
> any file descriptors because it wouldn't work, of course.

Or we fix the code to ALWAYS reorder file descriptors, including
updating the qemu code to use the reordered numbers instead of assuming
unchanged passthrough.  I'm still in the middle of an audit in my local
code base of what that would entail.


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

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