qapi: Separate type QNull from QObject

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

include/qapi/qmp/qobject.h

@@ -93,11 +93,15 @@ static inline QType qobject_type(const QObject *obj)
     return obj->type;
 }
 
-extern QObject qnull_;
+typedef struct QNull {
+    QObject base;
+} QNull;
 
-static inline QObject *qnull(void)
+extern QNull qnull_;
+
+static inline QNull *qnull(void)
 {
-    qobject_incref(&qnull_);
+    QINCREF(&qnull_);
     return &qnull_;
 }
 

qapi/qobject-output-visitor.c

@@ -190,7 +190,7 @@ static void qobject_output_type_any(Visitor *v, const char *name,
 static void qobject_output_type_null(Visitor *v, const char *name, Error **errp)
 {
     QObjectOutputVisitor *qov = to_qov(v);
-    qobject_output_add_obj(qov, name, qnull());
+    qobject_output_add(qov, name, qnull());
 }
 
 /* Finish building, and return the root object.

qobject/json-parser.c

@@ -445,7 +445,7 @@ static QObject *parse_keyword(JSONParserContext *ctxt)
     } else if (!strcmp(token->str, "false")) {
         return QOBJECT(qbool_from_bool(false));
     } else if (!strcmp(token->str, "null")) {
-        return qnull();
+        return QOBJECT(qnull());
     }
     parse_error(ctxt, token, "invalid keyword '%s'", token->str);
     return NULL;

qobject/qnull.c

@@ -14,7 +14,9 @@
 #include "qemu-common.h"
 #include "qapi/qmp/qobject.h"
 
-QObject qnull_ = {
-    .type = QTYPE_QNULL,
-    .refcnt = 1,
+QNull qnull_ = {
+    .base = {
+        .type = QTYPE_QNULL,
+        .refcnt = 1,
+    },
 };

target/i386/cpu.c

@@ -2442,7 +2442,7 @@ static QDict *x86_cpu_static_props(void)
 
     d = qdict_new();
     for (i = 0; props[i]; i++) {
-        qdict_put_obj(d, props[i], qnull());
+        qdict_put(d, props[i], qnull());
     }
 
     for (w = 0; w < FEATURE_WORDS; w++) {
@@ -2452,7 +2452,7 @@ static QDict *x86_cpu_static_props(void)
             if (!fi->feat_names[bit]) {
                 continue;
             }
-            qdict_put_obj(d, fi->feat_names[bit], qnull());
+            qdict_put(d, fi->feat_names[bit], qnull());
         }
     }
 

tests/check-qjson.c

@@ -1012,7 +1012,7 @@ static void keyword_literal(void)
 {
     QObject *obj;
     QBool *qbool;
-    QObject *null;
+    QNull *null;
     QString *str;
 
     obj = qobject_from_json("true", &error_abort);
@@ -1053,10 +1053,10 @@ static void keyword_literal(void)
     g_assert(qobject_type(obj) == QTYPE_QNULL);
 
     null = qnull();
-    g_assert(null == obj);
+    g_assert(QOBJECT(null) == obj);
 
     qobject_decref(obj);
-    qobject_decref(null);
+    QDECREF(null);
 }
 
 typedef struct LiteralQDictEntry LiteralQDictEntry;

tests/check-qnull.c

@@ -24,14 +24,14 @@ static void qnull_ref_test(void)
 {
     QObject *obj;
 
-    g_assert(qnull_.refcnt == 1);
-    obj = qnull();
+    g_assert(qnull_.base.refcnt == 1);
+    obj = QOBJECT(qnull());
     g_assert(obj);
-    g_assert(obj == &qnull_);
-    g_assert(qnull_.refcnt == 2);
+    g_assert(obj == QOBJECT(&qnull_));
+    g_assert(qnull_.base.refcnt == 2);
     g_assert(qobject_type(obj) == QTYPE_QNULL);
     qobject_decref(obj);
-    g_assert(qnull_.refcnt == 1);
+    g_assert(qnull_.base.refcnt == 1);
 }
 
 static void qnull_visit_test(void)
@@ -45,8 +45,8 @@ static void qnull_visit_test(void)
      * depend on layering violations to check qnull_ refcnt.
      */
 
-    g_assert(qnull_.refcnt == 1);
-    obj = qnull();
+    g_assert(qnull_.base.refcnt == 1);
+    obj = QOBJECT(qnull());
     v = qobject_input_visitor_new(obj);
     qobject_decref(obj);
     visit_type_null(v, NULL, &error_abort);
@@ -55,11 +55,11 @@ static void qnull_visit_test(void)
     v = qobject_output_visitor_new(&obj);
     visit_type_null(v, NULL, &error_abort);
     visit_complete(v, &obj);
-    g_assert(obj == &qnull_);
+    g_assert(obj == QOBJECT(&qnull_));
     qobject_decref(obj);
     visit_free(v);
 
-    g_assert(qnull_.refcnt == 1);
+    g_assert(qnull_.base.refcnt == 1);
 }
 
 int main(int argc, char **argv)