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

[Kevin Wolf]

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.

This series doesn't fix this, but the split makes a little more sense
after this patch at least...

Kevin