Re: [Qemu-devel] Adding errno to QMP errors

[Luiz Capitulino <lcapitulino@redhat.com>]

On Wed, 13 Jun 2012 14:49:10 -0300
Luiz Capitulino <lcapitulino@redhat.com> wrote:

> On Thu, 31 May 2012 16:54:47 +0200
> Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
> > Wait, I think you're conflating two things.
> > 
> > One is "do not shoehorn errors into errno values".  So for QOM invalid values we
> > have PropertyValueBad, not a generic InvalidArgument value.  We convert everything
> > to Error rather than returning negative errno values and then returning generic
> > error codes, because those would be ugly and non-descriptive.  I agree with that.
> > 
> > The other is "when errors come straight from the OS, _do_ use errno values".
> > This is for OpenFileFailed, for the new socket errors and so on.  This is what
> > I am proposing.
> 
> [...]
> 
> >     $ echo | sed p > /dev/full
> >     sed: couldn't flush stdout: No space left on device
> >          ^^^^^^^^^^^^^^                                 error type
> >                         ^^^^^^  ^^^^^^^^^^^^^^^^^^^^^^^ arguments
> > 
> > That would become, in JSON:
> > 
> >     { 'error': 'FlushFailed',
> >       'file': 'stdout',
> >       'os_error': 'enospc' }
> 
> This is not a new discussion and what we're doing today is to return errno
> as a QError class name. So, for the example above we'd return something like:
> 
>  { 'error': 'NoSpace' }
> 
> It's possible to add new optional values if you need more information, but
> I know that that's not what you're asking.
> 
> I mostly agree that your version would be better, the only problem I see
> is that this is probably going to mess a bit more our API as we have been
> doing like my example above for some time.
> 
> Anthony, the current design was mostly influenced by you and you had
> objections on doing what Paolo and Kevin are suggesting. What do you think?

Ping?

We have to reach a consensus of this because this is holding qapi conversions.