From 0db4f50397ac518e3674d0a4fa73c3a3c823060d Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@redhat.com>
Date: Fri, 17 Sep 2021 16:31:20 +0200
Subject: qapi: Convert simple union ImageInfoSpecific to flat one

Simple unions predate flat unions.  Having both complicates the QAPI
schema language and the QAPI generator.  We haven't been using simple
unions in new code for a long time, because they are less flexible and
somewhat awkward on the wire.

To prepare for their removal, convert simple union ImageInfoSpecific
to an equivalent flat one.  Adds some boilerplate to the schema, which
is a bit ugly, but a lot easier to maintain than the simple union
feature.

Implicit enum ImageInfoSpecificKind becomes explicit.  It duplicates
part of enum BlockdevDriver.  We could reuse BlockdevDriver instead.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210917143134.412106-10-armbru@redhat.com>
---
 qapi/block-core.json | 59 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 52 insertions(+), 7 deletions(-)

(limited to 'qapi')

diff --git a/qapi/block-core.json b/qapi/block-core.json
index c8ce1d9..623a4f4 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -140,6 +140,52 @@
   } }
 
 ##
+# @ImageInfoSpecificKind:
+#
+# @luks: Since 2.7
+# @rbd: Since 6.1
+#
+# Since: 1.7
+##
+{ 'enum': 'ImageInfoSpecificKind',
+  'data': [ 'qcow2', 'vmdk', 'luks', 'rbd' ] }
+
+##
+# @ImageInfoSpecificQCow2Wrapper:
+#
+# Since: 1.7
+##
+{ 'struct': 'ImageInfoSpecificQCow2Wrapper',
+  'data': { 'data': 'ImageInfoSpecificQCow2' } }
+
+##
+# @ImageInfoSpecificVmdkWrapper:
+#
+# Since: 6.1
+##
+{ 'struct': 'ImageInfoSpecificVmdkWrapper',
+  'data': { 'data': 'ImageInfoSpecificVmdk' } }
+
+##
+# @ImageInfoSpecificLUKSWrapper:
+#
+# Since: 2.7
+##
+{ 'struct': 'ImageInfoSpecificLUKSWrapper',
+  'data': { 'data': 'QCryptoBlockInfoLUKS' } }
+# If we need to add block driver specific parameters for
+# LUKS in future, then we'll subclass QCryptoBlockInfoLUKS
+# to define a ImageInfoSpecificLUKS
+
+##
+# @ImageInfoSpecificRbdWrapper:
+#
+# Since: 6.1
+##
+{ 'struct': 'ImageInfoSpecificRbdWrapper',
+  'data': { 'data': 'ImageInfoSpecificRbd' } }
+
+##
 # @ImageInfoSpecific:
 #
 # A discriminated record of image format specific information structures.
@@ -147,14 +193,13 @@
 # Since: 1.7
 ##
 { 'union': 'ImageInfoSpecific',
+  'base': { 'type': 'ImageInfoSpecificKind' },
+  'discriminator': 'type',
   'data': {
-      'qcow2': 'ImageInfoSpecificQCow2',
-      'vmdk': 'ImageInfoSpecificVmdk',
-      # If we need to add block driver specific parameters for
-      # LUKS in future, then we'll subclass QCryptoBlockInfoLUKS
-      # to define a ImageInfoSpecificLUKS
-      'luks': 'QCryptoBlockInfoLUKS',
-      'rbd': 'ImageInfoSpecificRbd'
+      'qcow2': 'ImageInfoSpecificQCow2Wrapper',
+      'vmdk': 'ImageInfoSpecificVmdkWrapper',
+      'luks': 'ImageInfoSpecificLUKSWrapper',
+      'rbd': 'ImageInfoSpecificRbdWrapper'
   } }
 
 ##
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