[PATCH v5 5/8] qapi: Implement deprecated-output=hide for QMP introspection

[Markus Armbruster]

This policy suppresses deprecated bits in output, and thus permits
"testing the future".  Implement it for QMP command query-qmp-schema:
suppress information on deprecated commands, events and object type
members, i.e. anything that has the special feature flag "deprecated".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qapi/introspect.json                 |   2 +-
 monitor/monitor-internal.h           |   3 -
 monitor/misc.c                       |   2 -
 monitor/qmp-cmds-control.c           | 100 +++++++++++++++++++++++----
 storage-daemon/qemu-storage-daemon.c |   2 -
 5 files changed, 89 insertions(+), 20 deletions(-)

diff --git a/qapi/introspect.json b/qapi/introspect.json
index 944bb87a20..39bd303778 100644
--- a/qapi/introspect.json
+++ b/qapi/introspect.json
@@ -49,7 +49,7 @@
 ##
 { 'command': 'query-qmp-schema',
   'returns': [ 'SchemaInfo' ],
-  'gen': false }                # just to simplify qmp_query_json()
+  'allow-preconfig': true }
 
 ##
 # @SchemaMetaType:
diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h
index b39e03b744..8833afaa65 100644
--- a/monitor/monitor-internal.h
+++ b/monitor/monitor-internal.h
@@ -180,7 +180,4 @@ void help_cmd(Monitor *mon, const char *name);
 void handle_hmp_command(MonitorHMP *mon, const char *cmdline);
 int hmp_compare_cmd(const char *name, const char *list);
 
-void qmp_query_qmp_schema(QDict *qdict, QObject **ret_data,
-                                 Error **errp);
-
 #endif
diff --git a/monitor/misc.c b/monitor/misc.c
index e847b58a8c..3fd335e737 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -242,8 +242,6 @@ static void monitor_init_qmp_commands(void)
 
     qmp_init_marshal(&qmp_commands);
 
-    qmp_register_command(&qmp_commands, "query-qmp-schema",
-                         qmp_query_qmp_schema, QCO_ALLOW_PRECONFIG);
     qmp_register_command(&qmp_commands, "device_add", qmp_device_add,
                          QCO_NO_OPTIONS);
     qmp_register_command(&qmp_commands, "object-add", qmp_object_add,
diff --git a/monitor/qmp-cmds-control.c b/monitor/qmp-cmds-control.c
index 8f04cfa6e6..5b07c7e765 100644
--- a/monitor/qmp-cmds-control.c
+++ b/monitor/qmp-cmds-control.c
@@ -26,10 +26,14 @@
 
 #include "monitor-internal.h"
 #include "qemu-version.h"
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-control.h"
+#include "qapi/qapi-commands-introspect.h"
 #include "qapi/qapi-emit-events.h"
 #include "qapi/qapi-introspect.h"
+#include "qapi/qapi-visit-introspect.h"
+#include "qapi/qobject-input-visitor.h"
 
 /*
  * Accept QMP capabilities in @list for @mon.
@@ -153,17 +157,89 @@ EventInfoList *qmp_query_events(Error **errp)
     return ev_list;
 }
 
-/*
- * Minor hack: generated marshalling suppressed for this command
- * ('gen': false in the schema) so we can parse the JSON string
- * directly into QObject instead of first parsing it with
- * visit_type_SchemaInfoList() into a SchemaInfoList, then marshal it
- * to QObject with generated output marshallers, every time.  Instead,
- * we do it in test-qobject-input-visitor.c, just to make sure
- * qapi-gen.py's output actually conforms to the schema.
- */
-void qmp_query_qmp_schema(QDict *qdict, QObject **ret_data,
-                                 Error **errp)
+static void *split_off_generic_list(void *list,
+                                    bool (*splitp)(void *elt),
+                                    void **part)
 {
-    *ret_data = qobject_from_qlit(&qmp_schema_qlit);
+    GenericList *keep = NULL, **keep_tailp = &keep;
+    GenericList *split = NULL, **split_tailp = &split;
+    GenericList *tail;
+
+    for (tail = list; tail; tail = tail->next) {
+        if (splitp(tail)) {
+            *split_tailp = tail;
+            split_tailp = &tail->next;
+        } else {
+            *keep_tailp = tail;
+            keep_tailp = &tail->next;
+        }
+    }
+
+    *keep_tailp = *split_tailp = NULL;
+    *part = split;
+    return keep;
+}
+
+static bool is_in(const char *s, strList *list)
+{
+    strList *tail;
+
+    for (tail = list; tail; tail = tail->next) {
+        if (!strcmp(tail->value, s)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+static bool is_entity_deprecated(void *link)
+{
+    return is_in("deprecated", ((SchemaInfoList *)link)->value->features);
+}
+
+static bool is_member_deprecated(void *link)
+{
+    return is_in("deprecated",
+                 ((SchemaInfoObjectMemberList *)link)->value->features);
+}
+
+static SchemaInfoList *zap_deprecated(SchemaInfoList *schema)
+{
+    void *to_zap;
+    SchemaInfoList *tail;
+    SchemaInfo *ent;
+
+    schema = split_off_generic_list(schema, is_entity_deprecated, &to_zap);
+    qapi_free_SchemaInfoList(to_zap);
+
+    for (tail = schema; tail; tail = tail->next) {
+        ent = tail->value;
+        if (ent->meta_type == SCHEMA_META_TYPE_OBJECT) {
+            ent->u.object.members
+                = split_off_generic_list(ent->u.object.members,
+                                         is_member_deprecated, &to_zap);
+            qapi_free_SchemaInfoObjectMemberList(to_zap);
+        }
+    }
+
+    return schema;
+}
+
+SchemaInfoList *qmp_query_qmp_schema(Error **errp)
+{
+    QObject *obj = qobject_from_qlit(&qmp_schema_qlit);
+    Visitor *v = qobject_input_visitor_new(obj);
+    SchemaInfoList *schema = NULL;
+
+    /* test_visitor_in_qmp_introspect() ensures this can't fail */
+    visit_type_SchemaInfoList(v, NULL, &schema, &error_abort);
+    g_assert(schema);
+
+    qobject_unref(obj);
+    visit_free(v);
+
+    if (compat_policy.deprecated_output == COMPAT_POLICY_OUTPUT_HIDE) {
+        return zap_deprecated(schema);
+    }
+    return schema;
 }
diff --git a/storage-daemon/qemu-storage-daemon.c 
b/storage-daemon/qemu-storage-daemon.c
index 7e9b0e0d3f..9490099036 100644
--- a/storage-daemon/qemu-storage-daemon.c
+++ b/storage-daemon/qemu-storage-daemon.c
@@ -142,8 +142,6 @@ static QemuOptsList qemu_object_opts = {
 static void init_qmp_commands(void)
 {
     qmp_init_marshal(&qmp_commands);
-    qmp_register_command(&qmp_commands, "query-qmp-schema",
-                         qmp_query_qmp_schema, QCO_ALLOW_PRECONFIG);
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-- 
2.26.2