Re: [Qemu-devel] [PATCH v2 1/8] qemu-error: introduce error_report_nolf

[Daniel P. Berrange]

On Thu, Jul 13, 2017 at 02:32:06PM +0100, Stefan Hajnoczi wrote:
> On Thu, Jul 13, 2017 at 01:02:30PM +0200, Ladi Prosek wrote:
> > +/*
> > + * Print an error message to current monitor if we have one, else to 
> > stderr.
> > + * Format arguments like sprintf().  The resulting message should be a
> > + * single phrase, with no trailing punctuation.  The no-LF version allows
> > + * additional text to be appended with error_printf() or error_vprintf().
> > + * Make sure to always close with a newline after all text is printed.
> > + * Prepends the current location.
> > + * It's wrong to call this in a QMP monitor.  Use error_setg() there.
> > + */
> > +void error_report_nolf(const char *fmt, ...)
> > +{
> > +    va_list ap;
> > +
> > +    va_start(ap, fmt);
> > +    error_vreport_nolf(fmt, ap);
> > +    va_end(ap);
> >  }
> 
> Each call to this function prepends the timestamp, so it cannot really
> be used for a sequence of prints in a single line.
> 
> It's a little ugly but I expected something along the lines of
> g_strdup_vprintf() in virtio_error():
> 
>   char *msg;
> 
>   va_start(ap, fmt);
>   msg = g_strdup_vprintf(fmt, ap);
>   va_end(ap);
> 
>   error_report("%s: %s", DEVICE(vdev)->id, msg);
> 
>   g_free(msg);

You could get the same thing by turning virtio_Error into a macro with
a few games. Rename the current method to virtio_error_impl() and then
define:

  #define virtio_error(dev, fmt, ...) \
     virtio_error_impl(dev, "%s: " fmt, DEVICE(dev)->id, __VA_ARGS__)

Regards,
Daniel
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