Re: [PATCH v2 01/12] block: Improve empty format-specific info dump

[Kevin Wolf <kwolf@redhat.com>]

Am 20.01.2023 um 14:35 hat Hanna Czenczek geschrieben:
> On 19.01.23 15:00, Kevin Wolf wrote:
> > Am 20.06.2022 um 18:26 hat Hanna Reitz geschrieben:
> > > When a block driver supports obtaining format-specific information, but
> > > that object only contains optional fields, it is possible that none of
> > > them are present, so that dump_qobject() (called by
> > > bdrv_image_info_specific_dump()) will not print anything.
> > > 
> > > The callers of bdrv_image_info_specific_dump() put a header above this
> > > information ("Format specific information:\n"), which will look strange
> > > when there is nothing below.  Modify bdrv_image_info_specific_dump() to
> > > print this header instead of its callers, and only if there is indeed
> > > something to be printed.
> > > 
> > > Signed-off-by: Hanna Reitz <hreitz@redhat.com>
> > > diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
> > > index 2f0d8ac25a..084ec44d3b 100644
> > > --- a/qemu-io-cmds.c
> > > +++ b/qemu-io-cmds.c
> > > @@ -1819,8 +1819,8 @@ static int info_f(BlockBackend *blk, int argc, char **argv)
> > >           return -EIO;
> > >       }
> > >       if (spec_info) {
> > > -        printf("Format specific information:\n");
> > > -        bdrv_image_info_specific_dump(spec_info);
> > > +        bdrv_image_info_specific_dump(spec_info,
> > > +                                      "Format specific information:\n");
> > >           qapi_free_ImageInfoSpecific(spec_info);
> > >       }
> > Interesting observation here: That qemu-io uses printf() instead of
> > qemu_printf() for the top level, but then dump_qobject() (which results
> > in qemu_printf()) for the format specific information, means that if you
> > use the 'qemu-io' HMP command, you'll get half of the output on stdout
> > and the other half in the monitor.
> 
> Hu.  I can’t find a single instance of qemu_printf() in qemu-io-cmds.c, but
> then I assume all printf()s there should really be qemu_printf()?

That would probably be the most consistent way.

I expect it would change the output of some qemu-iotests cases, but we
can explicitly print whatever was returned in QMP to keep the same
information in the test output.

Kevin