qom: fix ability to create objects without a parent

object_new_with_propv allowed id/parent to be optional, in which case
the caller was expected to own the returned object. Unfortunately a
trailing object_unref() meant that the returned object was already
freed.

It is confusing to have a single method with two different ownership
scenarios for the returned object.

Make id/parent mandatory in object_new_with_propv once more, and add
a new object_new_with_propv_parentless that does not accept id/parent
at all and lets the caller own the returned reference.

The helper method has abstracted the way properties are represented
and set in order to facilitate the subsequent commit.

Unit tests are added to address the root cause that allowed the bug
to slip through in commit 6134d752.

Fixes: 6134d7522e5 ("qom: don't require user creatable objects to be registered")
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

diff --git a/include/qom/object.h b/include/qom/object.h
index fb1cd92d9779a3a0c3a1d5fab061afa590cdfb1f..11f55613fcd085f58aed1c76b1d72a218fe5ff53 100644 (file)
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -719,6 +719,53 @@ Object *object_new_with_props_from_qdict(const char *typename,
                                          Visitor *v,
                                          Error **errp);
 
+/**
+ * object_new_with_props_parentless:
+ * @typename:  The name of the type of the object to instantiate.
+ * @errp: pointer to error object
+ * @...: list of property names and values
+ *
+ * Behaviour as object_new_with_props(), except the object
+ * will not be added to any parent and thus the caller will
+ * own the returned instance. The caller must call
+ * object_unref when it is no longer required.
+ */
+Object *object_new_with_props_parentless(const char *typename,
+                                         Error **errp,
+                                         ...) G_GNUC_NULL_TERMINATED;
+
+/**
+ * object_new_with_propv_parentless:
+ * @typename:  The name of the type of the object to instantiate.
+ * @vargs: list of property names and values
+ * @errp: pointer to error object
+ *
+ * Behaviour as object_new_with_propv(), except the object
+ * will not be added to any parent and thus the caller will
+ * own the returned instance. The caller must call
+ * object_unref when it is no longer required.
+ */
+Object *object_new_with_propv_parentless(const char *typename,
+                                         va_list vargs,
+                                         Error **errp);
+
+/**
+ * object_new_with_props_from_qdict_parentless:
+ * @typename:  The name of the type of the object to instantiate.
+ * @props: dictionary of property names and values
+ * @v: visitor to iterate over @props
+ * @errp: pointer to error object
+ *
+ * Behaviour as object_new_with_props_from_qdict(), except the
+ * object will not be added to any parent and thus the caller
+ * will own the returned instance. The caller must call
+ * object_unref when it is no longer required.
+ */
+Object *object_new_with_props_from_qdict_parentless(const char *typename,
+                                                    const QDict *props,
+                                                    Visitor *v,
+                                                    Error **errp);
+
 /**
  * object_set_props:
  * @obj: the object instance to set properties on

diff --git a/qom/object.c b/qom/object.c
index a11f559445e770545067cdbe2e2531f3315a8586..5a7ac457c14c28d25e961f5cd7a70104f3464aef 100644 (file)
--- a/qom/object.c
+++ b/qom/object.c
@@ -740,6 +740,8 @@ Object *object_new_with_props(const char *typename,
     va_list vargs;
     Object *obj;
 
+    assert(parent != NULL);
+    assert(id != NULL);
     va_start(vargs, errp);
     obj = object_new_with_propv(typename, parent, id, vargs, errp);
     va_end(vargs);
@@ -757,10 +759,14 @@ object_new_with_props_helper(const char *typename,
                                               Error **errp),
                              Error **errp)
 {
+    ERRP_GUARD();
     Object *obj;
     ObjectClass *klass;
     UserCreatable *uc;
 
+    assert((id != NULL && parent != NULL) ||
+           (id == NULL && parent == NULL));
+
     if (id != NULL && !id_wellformed(id)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "id", "an identifier");
         error_append_hint(errp, "Identifiers consist of letters, digits, "
@@ -785,7 +791,10 @@ object_new_with_props_helper(const char *typename,
     }
 
     if (id != NULL) {
-        object_property_add_child(parent, id, obj);
+        object_property_try_add_child(parent, id, obj, errp);
+        if (*errp) {
+            goto error;
+        }
     }
 
     uc = (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
@@ -798,7 +807,6 @@ object_new_with_props_helper(const char *typename,
         }
     }
 
-    object_unref(obj);
     return obj;
 
  error:
@@ -826,7 +834,8 @@ Object *object_new_with_propv(const char *typename,
 {
     Object *obj;
     struct ObjectNewVargsData data;
-
+    assert(parent != NULL);
+    assert(id != NULL);
     va_copy(data.vargs, vargs);
     obj = object_new_with_props_helper(typename,
                                        parent,
@@ -835,6 +844,9 @@ Object *object_new_with_propv(const char *typename,
                                        object_new_with_propv_setter,
                                        errp);
     va_end(data.vargs);
+    if (obj) {
+        object_unref(obj);
+    }
     return obj;
 }
 
@@ -859,12 +871,56 @@ Object *object_new_with_props_from_qdict(const char *typename,
                                          Error **errp)
 {
     struct ObjectNewQDictData data = { props, v };
-    return object_new_with_props_helper(typename,
-                                        parent,
-                                        id,
-                                        &data,
-                                        object_new_with_qdict_setter,
-                                        errp);
+    Object *obj;
+    assert(parent != NULL);
+    assert(id != NULL);
+    obj = object_new_with_props_helper(typename,
+                                       parent,
+                                       id,
+                                       &data,
+                                       object_new_with_qdict_setter,
+                                       errp);
+    if (obj) {
+        object_unref(obj);
+    }
+    return obj;
+}
+
+Object *object_new_with_props_parentless(const char *typename,
+                                         Error **errp,
+                                         ...)
+{
+    va_list vargs;
+    Object *obj;
+
+    va_start(vargs, errp);
+    obj = object_new_with_propv_parentless(typename, vargs, errp);
+    va_end(vargs);
+
+    return obj;
+}
+
+Object *object_new_with_propv_parentless(const char *typename,
+                                         va_list vargs,
+                                         Error **errp)
+{
+    Object *ret;
+    struct ObjectNewVargsData data;
+    va_copy(data.vargs, vargs);
+    ret = object_new_with_props_helper(typename, NULL, NULL, &data,
+                                       object_new_with_propv_setter, errp);
+    va_end(data.vargs);
+    return ret;
+}
+
+Object *object_new_with_props_from_qdict_parentless(const char *typename,
+                                                    const QDict *props,
+                                                    Visitor *v,
+                                                    Error **errp)
+{
+    struct ObjectNewQDictData data = { props, v };
+    return object_new_with_props_helper(typename, NULL, NULL, &data,
+                                        object_new_with_qdict_setter, errp);
 }
 
 bool object_set_props(Object *obj,

diff --git a/tests/unit/check-qom-proplist.c b/tests/unit/check-qom-proplist.c
index 7f31735459c90994f93d1f259ef4392f35d11b24..954c898ce17db6db1ae795c12f86f08a730b6258 100644 (file)
--- a/tests/unit/check-qom-proplist.c
+++ b/tests/unit/check-qom-proplist.c
@@ -336,7 +336,7 @@ static QemuOptsList qemu_object_opts = {
 };
 
 
-static void test_dummy_createv(void)
+static void test_dummy_createv_tree(void)
 {
     Error *err = NULL;
     Object *parent = object_get_objects_root();
@@ -351,6 +351,7 @@ static void test_dummy_createv(void)
                               NULL));
 
     g_assert(err == NULL);
+    g_assert_cmpint(dobj->parent_obj.ref, ==, 1);
     g_assert_cmpstr(dobj->sv, ==, "Hiss hiss hiss");
     g_assert(dobj->bv == true);
     g_assert(dobj->av == DUMMY_PLATYPUS);
@@ -362,9 +363,30 @@ static void test_dummy_createv(void)
 }
 
 
-static Object *new_helper(Error **errp,
-                          Object *parent,
-                          ...)
+static void test_dummy_createv_parentless(void)
+{
+    Error *err = NULL;
+    DummyObject *dobj = DUMMY_OBJECT(
+        object_new_with_props_parentless(TYPE_DUMMY,
+                                         &err,
+                                         "bv", "yes",
+                                         "sv", "Hiss hiss hiss",
+                                         "av", "platypus",
+                                         NULL));
+
+    g_assert(err == NULL);
+    g_assert_cmpint(dobj->parent_obj.ref, ==, 1);
+    g_assert_cmpstr(dobj->sv, ==, "Hiss hiss hiss");
+    g_assert(dobj->bv == true);
+    g_assert(dobj->av == DUMMY_PLATYPUS);
+
+    object_unref(OBJECT(dobj));
+}
+
+
+static Object *new_helper_tree(Error **errp,
+                               Object *parent,
+                               ...)
 {
     va_list vargs;
     Object *obj;
@@ -379,19 +401,20 @@ static Object *new_helper(Error **errp,
     return obj;
 }
 
-static void test_dummy_createlist(void)
+static void test_dummy_createlist_tree(void)
 {
     Error *err = NULL;
     Object *parent = object_get_objects_root();
     DummyObject *dobj = DUMMY_OBJECT(
-        new_helper(&err,
-                   parent,
-                   "bv", "yes",
-                   "sv", "Hiss hiss hiss",
-                   "av", "platypus",
-                   NULL));
+        new_helper_tree(&err,
+                        parent,
+                        "bv", "yes",
+                        "sv", "Hiss hiss hiss",
+                        "av", "platypus",
+                        NULL));
 
     g_assert(err == NULL);
+    g_assert_cmpint(dobj->parent_obj.ref, ==, 1);
     g_assert_cmpstr(dobj->sv, ==, "Hiss hiss hiss");
     g_assert(dobj->bv == true);
     g_assert(dobj->av == DUMMY_PLATYPUS);
@@ -402,6 +425,39 @@ static void test_dummy_createlist(void)
     object_unparent(OBJECT(dobj));
 }
 
+static Object *new_helper_parentless(Error **errp,
+                                     ...)
+{
+    va_list vargs;
+    Object *obj;
+
+    va_start(vargs, errp);
+    obj = object_new_with_propv_parentless(TYPE_DUMMY,
+                                           vargs,
+                                           errp);
+    va_end(vargs);
+    return obj;
+}
+
+static void test_dummy_createlist_parentless(void)
+{
+    Error *err = NULL;
+    DummyObject *dobj = DUMMY_OBJECT(
+        new_helper_parentless(&err,
+                              "bv", "yes",
+                              "sv", "Hiss hiss hiss",
+                              "av", "platypus",
+                              NULL));
+
+    g_assert(err == NULL);
+    g_assert_cmpint(dobj->parent_obj.ref, ==, 1);
+    g_assert_cmpstr(dobj->sv, ==, "Hiss hiss hiss");
+    g_assert(dobj->bv == true);
+    g_assert(dobj->av == DUMMY_PLATYPUS);
+
+    object_unref(OBJECT(dobj));
+}
+
 static bool test_create_obj(QDict *qdict, Error **errp)
 {
     Visitor *v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
@@ -658,8 +714,14 @@ int main(int argc, char **argv)
     type_register_static(&dummy_bus_info);
     type_register_static(&dummy_backend_info);
 
-    g_test_add_func("/qom/proplist/createlist", test_dummy_createlist);
-    g_test_add_func("/qom/proplist/createv", test_dummy_createv);
+    g_test_add_func("/qom/proplist/createlist/tree",
+                    test_dummy_createlist_tree);
+    g_test_add_func("/qom/proplist/createlist/parentless",
+                    test_dummy_createlist_parentless);
+    g_test_add_func("/qom/proplist/createv/tree",
+                    test_dummy_createv_tree);
+    g_test_add_func("/qom/proplist/createv/parentless",
+                    test_dummy_createv_parentless);
     g_test_add_func("/qom/proplist/createcmdline", test_dummy_createcmdl);
     g_test_add_func("/qom/proplist/badenum", test_dummy_badenum);
     g_test_add_func("/qom/proplist/getenum", test_dummy_getenum);