Simple unions are simpler than flat unions in the schema, but more
complicated in C and on the QMP wire: there's extra indirection in C
and extra nesting on the wire, both pointless.  They should be avoided
in new code.

GuestDeviceId was recently added for guest-get-devices.  Convert it to
a flat union.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qga/qapi-schema.json | 8 ++++++++
 qga/commands-win32.c | 9 ++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index c7bfb8bf6a..fe10631e4c 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -1256,6 +1256,12 @@
 { 'command': 'guest-get-osinfo',
   'returns': 'GuestOSInfo' }
 
+##
+# @GuestDeviceType:
+##
+{ 'enum': 'GuestDeviceType',
+  'data': [ 'pci' ] }
+
 ##
 # @GuestDeviceIdPCI:
 #
@@ -1276,6 +1282,8 @@
 # Since: 5.2
 ##
 { 'union': 'GuestDeviceId',
+  'base': { 'type': 'GuestDeviceType' },
+  'discriminator': 'type',
   'data': { 'pci': 'GuestDeviceIdPCI' } }
 
 ##
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 1efe3ba076..0c33d48aaa 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -2400,16 +2400,15 @@ GuestDeviceInfoList *qmp_guest_get_devices(Error **errp)
             }
             skip = false;
 
-            id = g_new0(GuestDeviceIdPCI, 1);
             vendor_id = g_match_info_fetch(match_info, 1);
             device_id = g_match_info_fetch(match_info, 2);
-            id->vendor_id = g_ascii_strtoull(vendor_id, NULL, 16);
-            id->device_id = g_ascii_strtoull(device_id, NULL, 16);
 
             device->id = g_new0(GuestDeviceId, 1);
             device->has_id = true;
-            device->id->type = GUEST_DEVICE_ID_KIND_PCI;
-            device->id->u.pci.data = id;
+            device->id->type = GUEST_DEVICE_TYPE_PCI;
+            id = &device->id->u.pci;
+            id->vendor_id = g_ascii_strtoull(vendor_id, NULL, 16);
+            id->device_id = g_ascii_strtoull(device_id, NULL, 16);
 
             g_match_info_free(match_info);
             break;
-- 
2.26.2

On 10/21/20 9:15 AM, Markus Armbruster wrote:
> Simple unions are simpler than flat unions in the schema, but more
> complicated in C and on the QMP wire: there's extra indirection in C
> and extra nesting on the wire, both pointless.  They should be avoided
> in new code.
> 
> GuestDeviceId was recently added for guest-get-devices.  Convert it to
> a flat union.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>   qga/qapi-schema.json | 8 ++++++++
>   qga/commands-win32.c | 9 ++++-----
>   2 files changed, 12 insertions(+), 5 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

On Wed, Oct 21, 2020 at 11:16 AM Markus Armbruster <armbru@redhat.com>
wrote:

> Simple unions are simpler than flat unions in the schema, but more
> complicated in C and on the QMP wire: there's extra indirection in C
> and extra nesting on the wire, both pointless.  They should be avoided
> in new code.
>
> GuestDeviceId was recently added for guest-get-devices.  Convert it to
> a flat union.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

---
>  qga/qapi-schema.json | 8 ++++++++
>  qga/commands-win32.c | 9 ++++-----
>  2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> index c7bfb8bf6a..fe10631e4c 100644
> --- a/qga/qapi-schema.json
> +++ b/qga/qapi-schema.json
> @@ -1256,6 +1256,12 @@
>  { 'command': 'guest-get-osinfo',
>    'returns': 'GuestOSInfo' }
>
> +##
> +# @GuestDeviceType:
> +##
> +{ 'enum': 'GuestDeviceType',
> +  'data': [ 'pci' ] }
> +
>  ##
>  # @GuestDeviceIdPCI:
>  #
> @@ -1276,6 +1282,8 @@
>  # Since: 5.2
>  ##
>  { 'union': 'GuestDeviceId',
> +  'base': { 'type': 'GuestDeviceType' },
> +  'discriminator': 'type',
>    'data': { 'pci': 'GuestDeviceIdPCI' } }
>
>  ##
> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
> index 1efe3ba076..0c33d48aaa 100644
> --- a/qga/commands-win32.c
> +++ b/qga/commands-win32.c
> @@ -2400,16 +2400,15 @@ GuestDeviceInfoList *qmp_guest_get_devices(Error
> **errp)
>              }
>              skip = false;
>
> -            id = g_new0(GuestDeviceIdPCI, 1);
>              vendor_id = g_match_info_fetch(match_info, 1);
>              device_id = g_match_info_fetch(match_info, 2);
> -            id->vendor_id = g_ascii_strtoull(vendor_id, NULL, 16);
> -            id->device_id = g_ascii_strtoull(device_id, NULL, 16);
>
>              device->id = g_new0(GuestDeviceId, 1);
>              device->has_id = true;
> -            device->id->type = GUEST_DEVICE_ID_KIND_PCI;
> -            device->id->u.pci.data = id;
> +            device->id->type = GUEST_DEVICE_TYPE_PCI;
> +            id = &device->id->u.pci;
> +            id->vendor_id = g_ascii_strtoull(vendor_id, NULL, 16);
> +            id->device_id = g_ascii_strtoull(device_id, NULL, 16);
>
>              g_match_info_free(match_info);
>              break;
> --
> 2.26.2
>
>
>

-- 
Marc-André Lureau