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Date: Wed, 10 Apr 2013 08:40:25 -0400
From: Luiz Capitulino <lcapitulino@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and
 introduce qmp command
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To: Eric Blake <eblake@redhat.com>
Cc: Pavel Hrdina <phrdina@redhat.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

On Wed, 10 Apr 2013 06:24:11 -0600
Eric Blake <eblake@redhat.com> wrote:

> >   - If you want to overwrite an existing snapshot, you could specify
> >     the 'id' or the 'name' argument or both of them and also you will
> >     have to use the 'force' argument
> 
> But the argument made in this thread is that QMP should _not_ have a
> force argument.  It should be a flat-out error in QMP to try to create a
> snapshot with a conflicting name or tag; preferably with a distinct
> error type.  Higher-level apps (HMP savevm -f) would try to create; if
> -f is not specified, the error is good enough; if -f is specified and
> that particular error is returned, then HMP calls delete and then
> re-tries the create.  No 'force' argument needed at the QMP layer.

To avoid adding a new error class, the HMP command could query for the
snapshot name and delete it if it exists before creating the snapshot.