Re: [Qemu-devel] [PATCH 01/11] qemu-img: introduce qemu_img_handle_error()

[Pavel Hrdina]

On 18.4.2013 14:59, Kevin Wolf wrote:
> Am 18.04.2013 um 13:52 hat Pavel Hrdina geschrieben:
> > On 18.4.2013 13:44, Kevin Wolf wrote:
> > > Am 16.04.2013 um 18:05 hat Pavel Hrdina geschrieben:
> > > > Later in the patch series we will use this function few times.
> > > > This will avoid of duplicating the code.
> > > >
> > > > Signed-off-by: Pavel Hrdina <address@hidden>
> > > > ---
> > > >   qemu-img.c | 17 +++++++++++------
> > > >   1 file changed, 11 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/qemu-img.c b/qemu-img.c
> > > > index 31627b0..dbacdb7 100644
> > > > --- a/qemu-img.c
> > > > +++ b/qemu-img.c
> > > > @@ -322,6 +322,16 @@ static int add_old_style_options(const char *fmt, 
> > > > QEMUOptionParameter *list,
> > > >       return 0;
> > > >   }
> > > >
> > > > +static int qemu_img_handle_error(const char *msg, Error *err)
> > > > +{
> > > > +    if (error_is_set(&err)) {
> > > > +        error_report("%s: %s", msg, error_get_pretty(err));
> > > > +        error_free(err);
> > > > +        return 1;
> > > > +    }
> > > > +    return 0;
> > > > +}
> > > > +
> > > >   static int img_create(int argc, char **argv)
> > > >   {
> > > >       int c;
> > > > @@ -400,13 +410,8 @@ static int img_create(int argc, char **argv)
> > > >
> > > >       bdrv_img_create(filename, fmt, base_filename, base_fmt,
> > > >                       options, img_size, BDRV_O_FLAGS, &local_err, quiet);
> > > > -    if (error_is_set(&local_err)) {
> > > > -        error_report("%s", error_get_pretty(local_err));
> > > > -        error_free(local_err);
> > > > -        return 1;
> > > > -    }
> > > >
> > > > -    return 0;
> > > > +    return qemu_img_handle_error("qemu-img create failed", local_err);
> > > >   }
> > >
> > > This makes a change to the error message that isn't mentioned in the
> > > commit message. It should definitely be mentioned there, but I'm not
> > > even sure if it's a good change. Today you get something like:
> > >
> > >      $ qemu-img create -f foo test.img
> > >      qemu-img: Unknown file format 'foo'
> > >
> > > With the patch applied it becomes:
> > >
> > >      $ qemu-img create -f foo test.img
> > >      qemu-img: qemu-img create failed: Unknown file format 'foo'
> > >
> > > Does this add any useful information or does it just make the error
> > > message longer? I feel it's the latter.
> > >
> > > Kevin
> >
> > Thanks for pointing this out, it should be
> > qemu_img_handle_error("create failed", local_err);
> >
> > and later in patch series also
> > qemu_img_handle_error("snapshot create failed", local_err);
> >
> > Is that OK after this change?
>
> I would in fact leave the error message as it is today. The "create
> failed" doesn't help me understand the error better. I already know that
> it's a create command that failed, because it was me who called 'qemu-img
> create'.
>
> Kevin

Yes that's true and make sense, but what if another tool internally uses 
the qemu-img command? I know that the tool could print/return/whatever 
proper error message, but qemu-img could help with that printing more 
information.

Pavel