Re: [Qemu-devel] [PATCH RFC v2 1/8] qmp: print dirty bitmap

[Eric Blake]

On 01/27/2015 03:56 AM, Vladimir Sementsov-Ogievskiy wrote:
> Adds qmp and hmp commands to print dirty bitmap. This is needed only for
> testing.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>  block.c               | 33 +++++++++++++++++++++++++++++++++
>  blockdev.c            | 13 +++++++++++++
>  hmp-commands.hx       | 15 +++++++++++++++
>  hmp.c                 |  8 ++++++++
>  hmp.h                 |  1 +
>  include/block/block.h |  2 ++
>  qapi-schema.json      |  3 ++-
>  qapi/block-core.json  |  3 +++
>  qmp-commands.hx       |  5 +++++
>  9 files changed, 82 insertions(+), 1 deletion(-)
> 

> +void bdrv_print_dirty_bitmap(BdrvDirtyBitmap *bitmap)
> +{
> +    unsigned long a = 0, b = 0;
> +
> +    printf("bitmap '%s'\n", bitmap->name ? bitmap->name : "no name");
> +    printf("enabled: %s\n", bitmap->enabled ? "true" : "false");
> +    printf("size: %" PRId64 "\n", bitmap->size);
> +    printf("granularity: %" PRId64 "\n", bitmap->granularity);
> +    printf("dirty regions begin:\n");
> +

> +void qmp_block_dirty_bitmap_print(const char *node_ref, const char *name,
> +                                  Error **errp)
> +{
> +    BdrvDirtyBitmap *bitmap;
> +
> +    bitmap = block_dirty_bitmap_lookup(node_ref, name, NULL, errp);
> +    if (!bitmap) {
> +        return;
> +    }
> +
> +    bdrv_print_dirty_bitmap(bitmap);

Won't work.  You cannot assume that stdout is usable when invoked from
QMP.  The only sane thing to do is to bundle up the structured data into
JSON, pass that back over the QMP connection, and let the client decide
how to print it.

I'm opposed to adding this command as-is.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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