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Re: [libvirt] [PATCH v4 0/8]: Add arbitrary qemu command-line and monitor commands

On Fri, Jul 09, 2010 at 03:03:59PM -0400, Chris Lalancette wrote:
> On 07/09/10 - 01:45:25PM, Charles Duffy wrote:
> > On 07/07/2010 04:33 PM, Chris Lalancette wrote:

  Now that 0.8.3 is out with all the patches except the problem of
access from virsh, it's time to look at this again :-)

> > >There is one bug left that I have not yet been able to fix.  Because of the
> > >complicated way that virsh parses command-line arguments, it is not possible
> > >to pass through spaces and quotes when using the qemu-monitor-command.
> > >Unfortunately, the qemu monitor commands (and in particular when using QMP)
> > >depend heavily on quoting and spacing, so using virsh to send through
> > >command-lines is difficult.  I'll have to think about how to better resolve
> > >this issue, but it should not hold up the rest of the series.
> > 
> > Would URI-style quoting (' ' -> %20) make sense here?
> We could keep that in mind as a last resort, though I'd prefer to try to fix
> fix the problem before resorting to it.  It's been a while since I looked
> at the problem in detail, but from what I remember virsh does this thing
> where it looks at everything in argv, smashes it all together (whitespace
> separated), and then re-parses it.  The problem with that is that if you do
> some careful quoting to get around bash whitespace issues, virsh undoes this
> for you.
> However, I couldn't easily fix it to *not* do this because of another feature
> that virsh has, which is the ability to specify multiple virsh sub-commands
> in one command, something like:
> virsh <guest> "attach-disk ; detach-disk"
> The combination of these make it difficult to fix, though I can't say I've
> exhausted all possibilities yet.

  I think we need 2 command to try to solve it:

 - one virsh command for non-interactive use, where the command is being
   passed from a file, that way we can provide a garanteed way the
   command won't get mangled by shell parsing or args.
 - one virsh command for interractive use where the command is parsed
   from the usual way (i.e. ether the result of shell parsing or what
   the user typed in interractive mode).

Also as a convenience I think we should patch virsh to accept '-' as
reading from the stdin, for all commands where we use a filename, that's
very convenient I use it quite a bit for xmllint, and would be useful
there too I think.


Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/

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