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Date: Wed, 06 May 2009 08:43:19 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] Add HTTP protocol using curl v2
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, alex@csgraf.de, nolan@sigbus.net, Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org

Daniel P. Berrange wrote:
> On Wed, May 06, 2009 at 08:12:56AM -0500, Anthony Liguori wrote:
>   
>> Avi Kivity wrote:
>>     
>>> Daniel P. Berrange wrote:
>>>       
>>>> Then I'd prefer we add a protocol=XXX option for magic protocols. 
>>>> This would be easier to use & clearer than requiring escaping of 
>>>> magic characters, eg
>>>>
>>>>   -drive file=/some/path:with:colons,protocol=file
>>>>   -drive file=http://some/path,protocol=uri
>>>>
>>>> For compatability, we could make it such that if protocol=XXX was 
>>>> left out,
>>>> it could try and "guess" it, in same way QEMU does if format=XXX is 
>>>> left out
>>>> for content format.
>>>>  
>>>>         
>>> How about
>>>
>>> -drive file=file:///some/path:with:colons?
>>>
>>> Libvirt would use this unconditionally, command-line users can choose.
>>>       
>> Why does libvirt care?  That confuses me.
>>     
>
> I don't have any problem with QEMU supporting http, nbd, or other clever
> file access schemes. I'll let others debate its merits vs using FUSE 
> http filesystems :-)
>
> All I care about from libvirt POV, is that there is a way to give QEMU an 
> absolute file path for a disk, and guarentee that QEMU will treat this as
> a local file path, and not try any access protocols, other than 'open(2)'.
> Various options from this thread....
>
>  - Treat any path starting with / as local file
>  - Allow file:  as a prefix
>  - Allow file:/// as a prefix, real URI style
>  - Add a protocol=file  flag to -drive
>   
The only viable solution is for libvirt to escape it's file names.

For instance, you're in all sorts of trouble if a user creates a 
filename that looks like 'My disk image,format=raw.img'

Regards,

Anthony Liguori