Re: [Qemu-devel] [RFC PATCH 05/11] qemu_fclose: return last_error if set

[Eduardo Habkost]

On Wed, Nov 02, 2011 at 01:15:46PM +0100, Paolo Bonzini wrote:
> On 11/02/2011 12:56 PM, Eduardo Habkost wrote:
> >No, if it's positive it won't be set on last_error, so we have to save
> >it somewhere other than last_error (that's what the qemu_close() return
> >value is used for).
> 
> Ok, I was confused by your patch 6, which basically removes the only
> case when qemu_fclose was returning a positive, nonzero value. :)  I
> guess the problem is there?

Yes! We must return the pclose() return value there, as exec_close()
needs it. Thanks for spotting it.  :-)

> 
> >Without a separate function and qemu_file_set_if_error(), the function
> >will look like:
> >
> >int qemu_fclose(QEMUFile *f)
> >{
> >     int ret = 0;
> >     qemu_fflush();
> >     if (f->close) {
> >         ret = f->close(f->opaque);
> >     }
> >     if (f->last_error) {
>            ^^^^^^^^^^^^^
> 
> "if (ret >= 0 && f->last_error)" perhaps?

I don't think so: if f->close() fails but we have already got an error
on any previous operation (in other words, if f->last_error was already
set), I think we should return info about the first error (that will
probably be more informative), instead of the close() error.

> 
> >         ret = f->last_error;
> >     }
> >     g_free(f);
> >     return ret;
> >}
> >
> >
> >Now that I am looking at the resulting code, it doesn't look too bad. I
> >guess I was simply too eager to encapsulate every bit of logic (in this
> >case the "if (f->close) ..." part) into separate functions. I find the
> >two-function version slightly easier to analyze, though.
> 
> Yes, it's the same for me too now that I actually understand what's
> going on.

Good.  :-)

-- 
Eduardo