[Qemu-devel] [PATCH v2 2/2] vl: Partial support for non-scalar properties with -object

[Markus Armbruster <armbru@redhat.com>]

We've wanted -object to support non-scalar properties for a while.
Dan Berrange tried in "[PATCH v4 00/10]Provide a QOM-based
authorization API".  Review led to the conclusion that we need to
replace rather than add to QemuOpts.  Initial work towards that goal
has been merged to provide -blockdev (commit 8746709), but there's
substantial work left, mostly due to an bewildering array of
compatibility problems.

Even if a full solution is still out of reach, we can have a partial
solution now: accept -object argument in JSON syntax.  This should
unblock development work that needs non-scalar properties with
-object.

The implementation is similar to -blockdev, except we use the new
infrastructure only for the new JSON case, and stick to QemuOpts for
the existing KEY=VALUE,... case, to sidestep compatibility problems.

If we did this for more options, we'd have to factor out common code.
But for one option, this will do.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qapi-schema.json | 14 +++++++++++---
 vl.c             | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/qapi-schema.json b/qapi-schema.json
index 802ea53..7ed1db1 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3618,15 +3618,23 @@
 { 'command': 'netdev_del', 'data': {'id': 'str'} }
 
 ##
-# @object-add:
+# @ObjectOptions:
 #
-# Create a QOM object.
+# Options for creating an object.
 #
 # @qom-type: the class name for the object to be created
 #
 # @id: the name of the new object
 #
 # @props: a dictionary of properties to be passed to the backend
+##
+{ 'struct': 'ObjectOptions',
+  'data': {'qom-type': 'str', 'id': 'str', '*props': 'any'} }
+
+##
+# @object-add:
+#
+# Create a QOM object.
 #
 # Returns: Nothing on success
 #          Error if @qom-type is not a valid class name
@@ -3642,7 +3650,7 @@
 #
 ##
 { 'command': 'object-add',
-  'data': {'qom-type': 'str', 'id': 'str', '*props': 'any'} }
+  'data': 'ObjectOptions' }
 
 ##
 # @object-del:
diff --git a/vl.c b/vl.c
index 96c5da1..cd9ab74 100644
--- a/vl.c
+++ b/vl.c
@@ -2855,8 +2855,36 @@ static bool object_create_delayed(const char *type)
     return !object_create_initial(type);
 }
 
+typedef struct ObjectOptionsQueueEntry {
+    ObjectOptions *oo;
+    Location loc;
+    QSIMPLEQ_ENTRY(ObjectOptionsQueueEntry) entry;
+} ObjectOptionsQueueEntry;
+
+typedef QSIMPLEQ_HEAD(ObjectOptionsQueue, ObjectOptionsQueueEntry)
+    ObjectOptionsQueue;
+
+ObjectOptionsQueue oo_queue = QSIMPLEQ_HEAD_INITIALIZER(oo_queue);
+
+
 static void object_create(bool (*type_predicate)(const char *))
 {
+    ObjectOptionsQueueEntry *e, *next;
+
+    QSIMPLEQ_FOREACH_SAFE(e, &oo_queue, entry, next) {
+        if (!type_predicate(e->oo->qom_type)) {
+            continue;
+        }
+
+        loc_push_restore(&e->loc);
+        qmp_object_add(e->oo->qom_type, e->oo->id,
+                       e->oo->has_props, e->oo->props, &error_fatal);
+        loc_pop(&e->loc);
+
+        QSIMPLEQ_REMOVE(&oo_queue, e, ObjectOptionsQueueEntry, entry);
+        qapi_free_ObjectOptions(e->oo);
+    }
+
     if (qemu_opts_foreach(qemu_find_opts("object"),
                           user_creatable_add_opts_foreach,
                           type_predicate, NULL)) {
@@ -4079,6 +4107,29 @@ int main(int argc, char **argv, char **envp)
 #endif
                 break;
             case QEMU_OPTION_object:
+                /*
+                 * TODO Use qobject_input_visitor_new_str() instead of
+                 * QemuOpts, not in addition to.  Not done now because
+                 * keyval_parse() isn't wart-compatible with QemuOpts.
+                 */
+                if (optarg[0] == '{') {
+                    Visitor *v;
+                    ObjectOptionsQueueEntry *e;
+
+                    v = qobject_input_visitor_new_str(optarg, "qom-type",
+                                                      &err);
+                    if (!v) {
+                        error_report_err(err);
+                        exit(1);
+                    }
+
+                    e = g_new(ObjectOptionsQueueEntry, 1);
+                    visit_type_ObjectOptions(v, NULL, &e->oo, &error_fatal);
+                    visit_free(v);
+                    loc_save(&e->loc);
+                    QSIMPLEQ_INSERT_TAIL(&oo_queue, e, entry);
+                    break;
+                }
                 opts = qemu_opts_parse_noisily(qemu_find_opts("object"),
                                                optarg, true);
                 if (!opts) {
-- 
2.7.5