The current -object command line syntax only allows for
creation of objects with scalar properties, or a list
with a fixed scalar element type. Objects which have
properties that are represented as structs in the QAPI
schema cannot be created using -object.

This is a design limitation of the way the OptsVisitor
is written. It simply iterates over the QemuOpts values
as a flat list. The support for lists is enabled by
allowing the same key to be repeated in the opts string.

It is not practical to extend the OptsVisitor to support
more complex data structures while also maintaining
the existing list handling behaviour that is relied upon
by other areas of QEMU.

Fortunately there is no existing object that implements
the UserCreatable interface that relies on the list
handling behaviour, so it is possible to swap out the
OptsVisitor for a different visitor implementation, so
-object supports non-scalar properties, thus leaving
other users of OptsVisitor unaffected.

The previously added qdict_crumple() method is able to
take a qdict containing a flat set of properties and
turn that into a arbitrarily nested set of dicts and
lists. By combining qemu_opts_to_qdict and qdict_crumple()
together, we can turn the opt string into a data structure
that is practically identical to that passed over QMP
when defining an object. The only difference is that all
the scalar values are represented as strings, rather than
strings, ints and bools. This is sufficient to let us
replace the OptsVisitor with the QObjectInputVisitor for
use with -object.

Thus -object can now support non-scalar properties,
for example the QMP object

  {
    "execute": "object-add",
    "arguments": {
      "qom-type": "demo",
      "id": "demo0",
      "parameters": {
        "foo": [
          { "bar": "one", "wizz": "1" },
          { "bar": "two", "wizz": "2" }
        ]
      }
    }
  }

Would be creatable via the CLI now using

    $QEMU \
      -object demo,id=demo0,\
              foo.0.bar=one,foo.0.wizz=1,\
              foo.1.bar=two,foo.1.wizz=2

Notice that this syntax is intentionally compatible
with that currently used by block drivers.

This is also wired up to work for the 'object_add' command
in the HMP monitor with the same syntax.

  (hmp) object_add demo,id=demo0,\
                   foo.0.bar=one,foo.0.wizz=1,\
                   foo.1.bar=two,foo.1.wizz=2

NB indentation should not be used with HMP commands, this
is just for convenient formatting in this commit message.

Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
---
 hmp.c                           |  16 +-
 include/qom/object_interfaces.h |  10 +-
 qmp.c                           |   2 +-
 qom/object_interfaces.c         |  45 ++++--
 tests/check-qom-proplist.c      | 334 +++++++++++++++++++++++++++++++++++++++-
 5 files changed, 378 insertions(+), 29 deletions(-)

diff --git a/hmp.c b/hmp.c
index ad33b44..834b6ae 100644
--- a/hmp.c
+++ b/hmp.c
@@ -25,7 +25,7 @@
 #include "qemu/sockets.h"
 #include "monitor/monitor.h"
 #include "monitor/qdev.h"
-#include "qapi/opts-visitor.h"
+#include "qapi/qobject-input-visitor.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/string-output-visitor.h"
 #include "qapi/util.h"
@@ -1695,20 +1695,14 @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict)
 void hmp_object_add(Monitor *mon, const QDict *qdict)
 {
     Error *err = NULL;
-    QemuOpts *opts;
     Visitor *v;
     Object *obj = NULL;
+    QDict *pdict = qdict_clone_shallow(qdict);
 
-    opts = qemu_opts_from_qdict(qemu_find_opts("object"), qdict, &err);
-    if (err) {
-        hmp_handle_error(mon, &err);
-        return;
-    }
-
-    v = opts_visitor_new(opts);
-    obj = user_creatable_add(qdict, v, &err);
+    v = qobject_string_input_visitor_new(QOBJECT(pdict));
+    obj = user_creatable_add(pdict, v, &err);
     visit_free(v);
-    qemu_opts_del(opts);
+    QDECREF(pdict);
 
     if (err) {
         hmp_handle_error(mon, &err);
diff --git a/include/qom/object_interfaces.h b/include/qom/object_interfaces.h
index 8b17f4d..2466e53 100644
--- a/include/qom/object_interfaces.h
+++ b/include/qom/object_interfaces.h
@@ -96,18 +96,24 @@ Object *user_creatable_add(const QDict *qdict,
  * user_creatable_add_type:
  * @type: the object type name
  * @id: the unique ID for the object
+ * @nested: whether to recurse into the visitor for properties
  * @qdict: the object properties
  * @v: the visitor
  * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Create an instance of the user creatable object @type, placing
  * it in the object composition tree with name @id, initializing
- * it with properties from @qdict
+ * it with properties from @qdict.
+ *
+ * If the visitor is already positioned to read the properties
+ * in @qdict, @nested should be false. Conversely, if it is
+ * necessary to open/close a struct to read the properties in
+ * @qdict, @nested should be true.
  *
  * Returns: the newly created object or NULL on error
  */
 Object *user_creatable_add_type(const char *type, const char *id,
-                                const QDict *qdict,
+                                bool nested, const QDict *qdict,
                                 Visitor *v, Error **errp);
 
 /**
diff --git a/qmp.c b/qmp.c
index 8786c1b..a074224 100644
--- a/qmp.c
+++ b/qmp.c
@@ -688,7 +688,7 @@ void qmp_object_add(const char *type, const char *id,
     }
 
     v = qobject_input_visitor_new(props, true);
-    obj = user_creatable_add_type(type, id, pdict, v, errp);
+    obj = user_creatable_add_type(type, id, true, pdict, v, errp);
     visit_free(v);
     if (obj) {
         object_unref(obj);
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index ded4d84..a68c39d 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -4,6 +4,7 @@
 #include "qemu/module.h"
 #include "qapi-visit.h"
 #include "qapi/qobject-output-visitor.h"
+#include "qapi/qobject-input-visitor.h"
 #include "qapi/opts-visitor.h"
 
 void user_creatable_complete(Object *obj, Error **errp)
@@ -63,12 +64,16 @@ Object *user_creatable_add(const QDict *qdict,
     if (local_err) {
         goto out_visit;
     }
-    visit_check_struct(v, &local_err);
+
+    obj = user_creatable_add_type(type, id, false, pdict, v, &local_err);
     if (local_err) {
         goto out_visit;
     }
 
-    obj = user_creatable_add_type(type, id, pdict, v, &local_err);
+    visit_check_struct(v, &local_err);
+    if (local_err) {
+        goto out_visit;
+    }
 
 out_visit:
     visit_end_struct(v, NULL);
@@ -87,7 +92,7 @@ out:
 
 
 Object *user_creatable_add_type(const char *type, const char *id,
-                                const QDict *qdict,
+                                bool nested, const QDict *qdict,
                                 Visitor *v, Error **errp)
 {
     Object *obj;
@@ -114,9 +119,11 @@ Object *user_creatable_add_type(const char *type, const 
char *id,
 
     assert(qdict);
     obj = object_new(type);
-    visit_start_struct(v, NULL, NULL, 0, &local_err);
-    if (local_err) {
-        goto out;
+    if (nested) {
+        visit_start_struct(v, NULL, NULL, 0, &local_err);
+        if (local_err) {
+            goto out;
+        }
     }
     for (e = qdict_first(qdict); e; e = qdict_next(qdict, e)) {
         object_property_set(obj, v, e->key, &local_err);
@@ -124,12 +131,14 @@ Object *user_creatable_add_type(const char *type, const 
char *id,
             break;
         }
     }
-    if (!local_err) {
-        visit_check_struct(v, &local_err);
-    }
-    visit_end_struct(v, NULL);
-    if (local_err) {
-        goto out;
+    if (nested) {
+        if (!local_err) {
+            visit_check_struct(v, &local_err);
+        }
+        visit_end_struct(v, NULL);
+        if (local_err) {
+            goto out;
+        }
     }
 
     object_property_add_child(object_get_objects_root(),
@@ -158,13 +167,21 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error 
**errp)
 {
     Visitor *v;
     QDict *pdict;
+    QObject *pobj;
     Object *obj = NULL;
 
-    v = opts_visitor_new(opts);
     pdict = qemu_opts_to_qdict(opts, NULL);
 
-    obj = user_creatable_add(pdict, v, errp);
+    pobj = qdict_crumple(pdict, true, errp);
+    if (!pobj) {
+        goto cleanup;
+    }
+    v = qobject_string_input_visitor_new(pobj);
+
+    obj = user_creatable_add(qobject_to_qdict(pobj), v, errp);
     visit_free(v);
+    qobject_decref(pobj);
+ cleanup:
     QDECREF(pdict);
     return obj;
 }
diff --git a/tests/check-qom-proplist.c b/tests/check-qom-proplist.c
index a16cefc..0bff55f 100644
--- a/tests/check-qom-proplist.c
+++ b/tests/check-qom-proplist.c
@@ -23,6 +23,14 @@
 #include "qapi/error.h"
 #include "qom/object.h"
 #include "qemu/module.h"
+#include "qapi/visitor.h"
+#include "qom/object_interfaces.h"
+#include "qemu/option.h"
+#include "qemu/config-file.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi-visit.h"
+#include "qapi/dealloc-visitor.h"
 
 
 #define TYPE_DUMMY "qemu-dummy"
@@ -30,6 +38,11 @@
 typedef struct DummyObject DummyObject;
 typedef struct DummyObjectClass DummyObjectClass;
 
+typedef struct DummyPerson DummyPerson;
+typedef struct DummyAddr DummyAddr;
+typedef struct DummyAddrList DummyAddrList;
+typedef struct DummySizeList DummySizeList;
+
 #define DUMMY_OBJECT(obj)                               \
     OBJECT_CHECK(DummyObject, (obj), TYPE_DUMMY)
 
@@ -50,12 +63,35 @@ static const char *const dummy_animal_map[DUMMY_LAST + 1] = 
{
     [DUMMY_LAST] = NULL,
 };
 
+
+struct DummyAddr {
+    char *ip;
+    int64_t prefix;
+    bool ipv6only;
+};
+
+struct DummyAddrList {
+    DummyAddrList *next;
+    struct DummyAddr *value;
+};
+
+struct DummyPerson {
+    char *name;
+    int64_t age;
+};
+
 struct DummyObject {
     Object parent_obj;
 
     bool bv;
     DummyAnimal av;
     char *sv;
+
+    intList *sizes;
+
+    DummyPerson *person;
+
+    DummyAddrList *addrs;
 };
 
 struct DummyObjectClass {
@@ -117,6 +153,157 @@ static char *dummy_get_sv(Object *obj,
     return g_strdup(dobj->sv);
 }
 
+static void visit_type_DummyPerson_fields(Visitor *v, DummyPerson **obj,
+                                          Error **errp)
+{
+    Error *err = NULL;
+
+    visit_type_str(v, "name", &(*obj)->name, &err);
+    if (err) {
+        goto out;
+    }
+    visit_type_int(v, "age", &(*obj)->age, &err);
+    if (err) {
+        goto out;
+    }
+
+out:
+    error_propagate(errp, err);
+}
+
+static void visit_type_DummyPerson(Visitor *v, const char *name,
+                                   DummyPerson **obj, Error **errp)
+{
+    Error *err = NULL;
+
+    visit_start_struct(v, name, (void **)obj, sizeof(DummyPerson), &err);
+    if (err) {
+        goto out;
+    }
+    if (!*obj) {
+        goto out_obj;
+    }
+    visit_type_DummyPerson_fields(v, obj, &err);
+    error_propagate(errp, err);
+    err = NULL;
+out_obj:
+    visit_end_struct(v, (void **)obj);
+out:
+    error_propagate(errp, err);
+}
+
+static void visit_type_DummyAddr_members(Visitor *v, DummyAddr **obj,
+                                         Error **errp)
+{
+    Error *err = NULL;
+
+    visit_type_str(v, "ip", &(*obj)->ip, &err);
+    if (err) {
+        goto out;
+    }
+    visit_type_int(v, "prefix", &(*obj)->prefix, &err);
+    if (err) {
+        goto out;
+    }
+    visit_type_bool(v, "ipv6only", &(*obj)->ipv6only, &err);
+    if (err) {
+        goto out;
+    }
+
+out:
+    error_propagate(errp, err);
+}
+
+static void visit_type_DummyAddr(Visitor *v, const char *name,
+                                 DummyAddr **obj, Error **errp)
+{
+    Error *err = NULL;
+
+    visit_start_struct(v, name, (void **)obj, sizeof(DummyAddr), &err);
+    if (err) {
+        goto out;
+    }
+    if (!*obj) {
+        goto out_obj;
+    }
+    visit_type_DummyAddr_members(v, obj, &err);
+    error_propagate(errp, err);
+    err = NULL;
+out_obj:
+    visit_end_struct(v, (void **)obj);
+out:
+    error_propagate(errp, err);
+}
+
+static void qapi_free_DummyAddrList(DummyAddrList *obj);
+
+static void visit_type_DummyAddrList(Visitor *v, const char *name,
+                                     DummyAddrList **obj, Error **errp)
+{
+    Error *err = NULL;
+    DummyAddrList *tail;
+    size_t size = sizeof(**obj);
+
+    visit_start_list(v, name, (GenericList **)obj, size, &err);
+    if (err) {
+        goto out;
+    }
+
+    for (tail = *obj; tail;
+         tail = (DummyAddrList *)visit_next_list(v,
+                                                 (GenericList *)tail,
+                                                 size)) {
+        visit_type_DummyAddr(v, NULL, &tail->value, &err);
+        if (err) {
+            break;
+        }
+    }
+
+    visit_end_list(v, (void **)obj);
+    if (err && visit_is_input(v)) {
+        qapi_free_DummyAddrList(*obj);
+        *obj = NULL;
+    }
+out:
+    error_propagate(errp, err);
+}
+
+static void qapi_free_DummyAddrList(DummyAddrList *obj)
+{
+    Visitor *v;
+
+    if (!obj) {
+        return;
+    }
+
+    v = qapi_dealloc_visitor_new();
+    visit_type_DummyAddrList(v, NULL, &obj, NULL);
+    visit_free(v);
+}
+
+static void dummy_set_sizes(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    DummyObject *dobj = DUMMY_OBJECT(obj);
+
+    visit_type_intList(v, name, &dobj->sizes, errp);
+}
+
+static void dummy_set_person(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    DummyObject *dobj = DUMMY_OBJECT(obj);
+
+    visit_type_DummyPerson(v, name, &dobj->person, errp);
+}
+
+static void dummy_set_addrs(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    DummyObject *dobj = DUMMY_OBJECT(obj);
+
+    visit_type_DummyAddrList(v, name, &dobj->addrs, errp);
+}
 
 static void dummy_init(Object *obj)
 {
@@ -126,9 +313,16 @@ static void dummy_init(Object *obj)
                              NULL);
 }
 
+static void
+dummy_complete(UserCreatable *uc, Error **errp)
+{
+}
 
 static void dummy_class_init(ObjectClass *cls, void *data)
 {
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(cls);
+    ucc->complete = dummy_complete;
+
     object_class_property_add_bool(cls, "bv",
                                    dummy_get_bv,
                                    dummy_set_bv,
@@ -143,12 +337,34 @@ static void dummy_class_init(ObjectClass *cls, void *data)
                                    dummy_get_av,
                                    dummy_set_av,
                                    NULL);
+    object_class_property_add(cls, "sizes",
+                              "int[]",
+                              NULL,
+                              dummy_set_sizes,
+                              NULL, NULL, NULL);
+    object_class_property_add(cls, "person",
+                              "DummyPerson",
+                              NULL,
+                              dummy_set_person,
+                              NULL, NULL, NULL);
+    object_class_property_add(cls, "addrs",
+                              "DummyAddrList",
+                              NULL,
+                              dummy_set_addrs,
+                              NULL, NULL, NULL);
 }
 
 
 static void dummy_finalize(Object *obj)
 {
     DummyObject *dobj = DUMMY_OBJECT(obj);
+    Visitor *v;
+
+    v = qapi_dealloc_visitor_new();
+    visit_type_intList(v, NULL, &dobj->sizes, NULL);
+    visit_type_DummyAddrList(v, NULL, &dobj->addrs, NULL);
+    visit_type_DummyPerson(v, NULL, &dobj->person, NULL);
+    visit_free(v);
 
     g_free(dobj->sv);
 }
@@ -162,6 +378,10 @@ static const TypeInfo dummy_info = {
     .instance_finalize = dummy_finalize,
     .class_size = sizeof(DummyObjectClass),
     .class_init = dummy_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
 };
 
 
@@ -473,7 +693,9 @@ static void test_dummy_iterator(void)
 
     ObjectProperty *prop;
     ObjectPropertyIterator iter;
-    bool seenbv = false, seensv = false, seenav = false, seentype;
+    bool seenbv = false, seensv = false, seenav = false,
+        seentype = false, seenaddrs = false, seenperson = false,
+        seensizes = false;
 
     object_property_iter_init(&iter, OBJECT(dobj));
     while ((prop = object_property_iter_next(&iter))) {
@@ -486,6 +708,12 @@ static void test_dummy_iterator(void)
         } else if (g_str_equal(prop->name, "type")) {
             /* This prop comes from the base Object class */
             seentype = true;
+        } else if (g_str_equal(prop->name, "addrs")) {
+            seenaddrs = true;
+        } else if (g_str_equal(prop->name, "person")) {
+            seenperson = true;
+        } else if (g_str_equal(prop->name, "sizes")) {
+            seensizes = true;
         } else {
             g_printerr("Found prop '%s'\n", prop->name);
             g_assert_not_reached();
@@ -495,6 +723,9 @@ static void test_dummy_iterator(void)
     g_assert(seenav);
     g_assert(seensv);
     g_assert(seentype);
+    g_assert(seenaddrs);
+    g_assert(seenperson);
+    g_assert(seensizes);
 
     object_unparent(OBJECT(dobj));
 }
@@ -513,11 +744,109 @@ static void test_dummy_delchild(void)
     object_unparent(OBJECT(dev));
 }
 
+
+static QemuOptsList dummy_opts = {
+    .name = "object",
+    .implied_opt_name = "qom-type",
+    .head = QTAILQ_HEAD_INITIALIZER(dummy_opts.head),
+    .desc = {
+        { }
+    },
+};
+
+static void test_dummy_create_complex(DummyObject *dummy)
+{
+    g_assert(dummy->person != NULL);
+    g_assert_cmpstr(dummy->person->name, ==, "fred");
+    g_assert_cmpint(dummy->person->age, ==, 52);
+
+    g_assert(dummy->sizes != NULL);
+    g_assert_cmpint(dummy->sizes->value, ==, 12);
+    g_assert_cmpint(dummy->sizes->next->value, ==, 65);
+    g_assert_cmpint(dummy->sizes->next->next->value, ==, 8139);
+
+    g_assert(dummy->addrs != NULL);
+    g_assert_cmpstr(dummy->addrs->value->ip, ==, "127.0.0.1");
+    g_assert_cmpint(dummy->addrs->value->prefix, ==, 24);
+    g_assert(dummy->addrs->value->ipv6only);
+    g_assert_cmpstr(dummy->addrs->next->value->ip, ==, "0.0.0.0");
+    g_assert_cmpint(dummy->addrs->next->value->prefix, ==, 16);
+    g_assert(!dummy->addrs->next->value->ipv6only);
+}
+
+
+static void test_dummy_createopts(void)
+{
+    const char *optstr = "qemu-dummy,id=dummy0,bv=yes,av=alligator,sv=hiss,"
+        "person.name=fred,person.age=52,sizes.0=12,sizes.1=65,sizes.2=8139,"
+        "addrs.0.ip=127.0.0.1,addrs.0.prefix=24,addrs.0.ipv6only=yes,"
+        "addrs.1.ip=0.0.0.0,addrs.1.prefix=16,addrs.1.ipv6only=no";
+    QemuOpts *opts;
+    DummyObject *dummy;
+
+    opts = qemu_opts_parse_noisily(&dummy_opts,
+                                   optstr, true);
+    g_assert(opts != NULL);
+
+    dummy = DUMMY_OBJECT(user_creatable_add_opts(opts, &error_abort));
+
+    test_dummy_create_complex(dummy);
+
+    object_unparent(OBJECT(dummy));
+    object_unref(OBJECT(dummy));
+}
+
+
+static void test_dummy_createopts_bad(void)
+{
+    /* Something that tries to create a QList at the top level
+     * should be invalid. */
+    const char *optstr = "qemu-dummy,1=foo,2=bar,3=wizz";
+    QemuOpts *opts;
+    DummyObject *dummy;
+    Error *err = NULL;
+
+    opts = qemu_opts_parse_noisily(&dummy_opts,
+                                   optstr, true);
+    g_assert(opts != NULL);
+
+    dummy = DUMMY_OBJECT(user_creatable_add_opts(opts, &err));
+    error_free_or_abort(&err);
+    g_assert(!dummy);
+}
+
+
+static void test_dummy_createqmp(void)
+{
+    const char *jsonstr =
+        "{ 'qom-type': 'qemu-dummy', 'id': 'dummy0', "
+        "  'bv': true, 'av': 'alligator', 'sv': 'hiss', "
+        "  'person': { 'name': 'fred', 'age': 52 }, "
+        "  'sizes': [12, 65, 8139], "
+        "  'addrs': [ { 'ip': '127.0.0.1', 'prefix': 24, 'ipv6only': true }, "
+        "             { 'ip': '0.0.0.0', 'prefix': 16, 'ipv6only': false } ] 
}";
+    QObject *obj = qobject_from_json(jsonstr);
+    Visitor *v = qobject_input_visitor_new(obj, true);
+    DummyObject *dummy;
+    g_assert(obj);
+    dummy = DUMMY_OBJECT(user_creatable_add(qobject_to_qdict(obj), v,
+                                            &error_abort));
+
+    test_dummy_create_complex(dummy);
+    visit_free(v);
+    object_unparent(OBJECT(dummy));
+    object_unref(OBJECT(dummy));
+    qobject_decref(obj);
+}
+
 int main(int argc, char **argv)
 {
     g_test_init(&argc, &argv, NULL);
 
     module_call_init(MODULE_INIT_QOM);
+
+    qemu_add_opts(&dummy_opts);
+
     type_register_static(&dummy_info);
     type_register_static(&dummy_dev_info);
     type_register_static(&dummy_bus_info);
@@ -529,6 +858,9 @@ int main(int argc, char **argv)
     g_test_add_func("/qom/proplist/getenum", test_dummy_getenum);
     g_test_add_func("/qom/proplist/iterator", test_dummy_iterator);
     g_test_add_func("/qom/proplist/delchild", test_dummy_delchild);
+    g_test_add_func("/qom/proplist/createopts", test_dummy_createopts);
+    g_test_add_func("/qom/proplist/createoptsbad", test_dummy_createopts_bad);
+    g_test_add_func("/qom/proplist/createqmp", test_dummy_createqmp);
 
     return g_test_run();
 }
-- 
2.7.4


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