qom: add the base Object class (v2)

This class provides the main building block for QEMU Object Model and is
extensively documented in the header file.  It is largely inspired by GObject.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
v1 -> v2
 - remove printf() in type registration
 - fix typo in comment (Paolo)
 - make Interface private
 - move object into a new directory and move header into include/qemu/
 - don't make object.h depend on qemu-common.h
 - remove Type and replace it with TypeImpl * (Paolo)
 - use hash table to store types (Paolo)
 - aggressively cache parent type (Paolo)
 - make a type_register and use it with interfaces (Paolo)
 - fix interface cast comment (Paolo)
 - add a few more functions required in later series

2 files changed, 486 insertions, 0 deletions

diff --git a/qom/Makefile b/qom/Makefile
new file mode 100644
index 0000000000..a3c789207e
--- /dev/null
+++ b/qom/Makefile
@@ -0,0 +1 @@
+qom-y = object.o
diff --git a/qom/object.c b/qom/object.c
new file mode 100644
index 0000000000..ef37e080d4
--- /dev/null
+++ b/qom/object.c
@@ -0,0 +1,485 @@
+/*
+ * QEMU Object Model
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/object.h"
+#include "qemu-common.h"
+
+#define MAX_INTERFACES 32
+
+typedef struct InterfaceImpl InterfaceImpl;
+typedef struct TypeImpl TypeImpl;
+
+struct InterfaceImpl
+{
+    const char *parent;
+    void (*interface_initfn)(ObjectClass *class, void *data);
+    TypeImpl *type;
+};
+
+struct TypeImpl
+{
+    const char *name;
+
+    size_t class_size;
+
+    size_t instance_size;
+
+    void (*class_init)(ObjectClass *klass, void *data);
+    void (*class_finalize)(ObjectClass *klass, void *data);
+
+    void *class_data;
+
+    void (*instance_init)(Object *obj);
+    void (*instance_finalize)(Object *obj);
+
+    bool abstract;
+
+    const char *parent;
+    TypeImpl *parent_type;
+
+    ObjectClass *class;
+
+    int num_interfaces;
+    InterfaceImpl interfaces[MAX_INTERFACES];
+};
+
+typedef struct Interface
+{
+    Object parent;
+    Object *obj;
+} Interface;
+
+#define INTERFACE(obj) OBJECT_CHECK(Interface, obj, TYPE_INTERFACE)
+
+static GHashTable *type_table_get(void)
+{
+    static GHashTable *type_table;
+
+    if (type_table == NULL) {
+        type_table = g_hash_table_new(g_str_hash, g_str_equal);
+    }
+
+    return type_table;
+}
+
+static void type_table_add(TypeImpl *ti)
+{
+    g_hash_table_insert(type_table_get(), (void *)ti->name, ti);
+}
+
+static TypeImpl *type_table_lookup(const char *name)
+{
+    return g_hash_table_lookup(type_table_get(), name);
+}
+
+TypeImpl *type_register(const TypeInfo *info)
+{
+    TypeImpl *ti = g_malloc0(sizeof(*ti));
+
+    g_assert(info->name != NULL);
+
+    ti->name = g_strdup(info->name);
+    ti->parent = g_strdup(info->parent);
+
+    ti->class_size = info->class_size;
+    ti->instance_size = info->instance_size;
+
+    ti->class_init = info->class_init;
+    ti->class_finalize = info->class_finalize;
+    ti->class_data = info->class_data;
+
+    ti->instance_init = info->instance_init;
+    ti->instance_finalize = info->instance_finalize;
+
+    ti->abstract = info->abstract;
+
+    if (info->interfaces) {
+        int i;
+
+        for (i = 0; info->interfaces[i].type; i++) {
+            ti->interfaces[i].parent = info->interfaces[i].type;
+            ti->interfaces[i].interface_initfn = info->interfaces[i].interface_initfn;
+            ti->num_interfaces++;
+        }
+    }
+
+    type_table_add(ti);
+
+    return ti;
+}
+
+TypeImpl *type_register_static(const TypeInfo *info)
+{
+    return type_register(info);
+}
+
+static TypeImpl *type_get_by_name(const char *name)
+{
+    if (name == NULL) {
+        return NULL;
+    }
+
+    return type_table_lookup(name);
+}
+
+static TypeImpl *type_get_parent(TypeImpl *type)
+{
+    if (!type->parent_type && type->parent) {
+        type->parent_type = type_get_by_name(type->parent);
+        g_assert(type->parent_type != NULL);
+    }
+
+    return type->parent_type;
+}
+
+static bool type_has_parent(TypeImpl *type)
+{
+    return (type->parent != NULL);
+}
+
+static size_t type_class_get_size(TypeImpl *ti)
+{
+    if (ti->class_size) {
+        return ti->class_size;
+    }
+
+    if (type_has_parent(ti)) {
+        return type_class_get_size(type_get_parent(ti));
+    }
+
+    return sizeof(ObjectClass);
+}
+
+static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)
+{
+    TypeInfo info = {
+        .instance_size = sizeof(Interface),
+        .parent = iface->parent,
+        .class_size = sizeof(InterfaceClass),
+        .class_init = iface->interface_initfn,
+        .abstract = true,
+    };
+    char *name = g_strdup_printf("<%s::%s>", ti->name, iface->parent);
+
+    info.name = name;
+    iface->type = type_register(&info);
+    g_free(name);
+}
+
+static void type_class_init(TypeImpl *ti)
+{
+    size_t class_size = sizeof(ObjectClass);
+    int i;
+
+    if (ti->class) {
+        return;
+    }
+
+    ti->class_size = type_class_get_size(ti);
+
+    ti->class = g_malloc0(ti->class_size);
+    ti->class->type = ti;
+
+    if (type_has_parent(ti)) {
+        TypeImpl *parent = type_get_parent(ti);
+
+        type_class_init(parent);
+
+        class_size = parent->class_size;
+        g_assert(parent->class_size <= ti->class_size);
+
+        memcpy((void *)ti->class + sizeof(ObjectClass),
+               (void *)parent->class + sizeof(ObjectClass),
+               parent->class_size - sizeof(ObjectClass));
+    }
+
+    memset((void *)ti->class + class_size, 0, ti->class_size - class_size);
+
+    for (i = 0; i < ti->num_interfaces; i++) {
+        type_class_interface_init(ti, &ti->interfaces[i]);
+    }
+
+    if (ti->class_init) {
+        ti->class_init(ti->class, ti->class_data);
+    }
+}
+
+static void object_interface_init(Object *obj, InterfaceImpl *iface)
+{
+    TypeImpl *ti = iface->type;
+    Interface *iface_obj;
+
+    iface_obj = INTERFACE(object_new(ti->name));
+    iface_obj->obj = obj;
+
+    obj->interfaces = g_slist_prepend(obj->interfaces, iface_obj);
+}
+
+static void object_init_with_type(Object *obj, TypeImpl *ti)
+{
+    int i;
+
+    if (type_has_parent(ti)) {
+        object_init_with_type(obj, type_get_parent(ti));
+    }
+
+    for (i = 0; i < ti->num_interfaces; i++) {
+        object_interface_init(obj, &ti->interfaces[i]);
+    }
+
+    if (ti->instance_init) {
+        ti->instance_init(obj);
+    }
+}
+
+void object_initialize_with_type(void *data, TypeImpl *type)
+{
+    Object *obj = data;
+
+    g_assert(type != NULL);
+    g_assert(type->instance_size >= sizeof(ObjectClass));
+
+    type_class_init(type);
+    g_assert(type->abstract == false);
+
+    memset(obj, 0, type->instance_size);
+    obj->class = type->class;
+    object_init_with_type(obj, type);
+}
+
+void object_initialize(void *data, const char *typename)
+{
+    TypeImpl *type = type_get_by_name(typename);
+
+    object_initialize_with_type(data, type);
+}
+
+static void object_deinit(Object *obj, TypeImpl *type)
+{
+    if (type->instance_finalize) {
+        type->instance_finalize(obj);
+    }
+
+    while (obj->interfaces) {
+        Interface *iface_obj = obj->interfaces->data;
+        obj->interfaces = g_slist_delete_link(obj->interfaces, obj->interfaces);
+        object_delete(OBJECT(iface_obj));
+    }
+
+    if (type_has_parent(type)) {
+        object_deinit(obj, type_get_parent(type));
+    }
+}
+
+void object_finalize(void *data)
+{
+    Object *obj = data;
+    TypeImpl *ti = obj->class->type;
+
+    object_deinit(obj, ti);
+}
+
+Object *object_new_with_type(Type type)
+{
+    Object *obj;
+
+    g_assert(type != NULL);
+
+    obj = g_malloc(type->instance_size);
+    object_initialize_with_type(obj, type);
+
+    return obj;
+}
+
+Object *object_new(const char *typename)
+{
+    TypeImpl *ti = type_get_by_name(typename);
+
+    return object_new_with_type(ti);
+}
+
+void object_delete(Object *obj)
+{
+    object_finalize(obj);
+    g_free(obj);
+}
+
+static bool object_is_type(Object *obj, const char *typename)
+{
+    TypeImpl *target_type = type_get_by_name(typename);
+    TypeImpl *type = obj->class->type;
+    GSList *i;
+
+    /* Check if typename is a direct ancestor of type */
+    while (type) {
+        if (type == target_type) {
+            return true;
+        }
+
+        type = type_get_parent(type);
+    }
+
+    /* Check if obj has an interface of typename */
+    for (i = obj->interfaces; i; i = i->next) {
+        Interface *iface = i->data;
+
+        if (object_is_type(OBJECT(iface), typename)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+Object *object_dynamic_cast(Object *obj, const char *typename)
+{
+    GSList *i;
+
+    /* Check if typename is a direct ancestor */
+    if (object_is_type(obj, typename)) {
+        return obj;
+    }
+
+    /* Check if obj has an interface of typename */
+    for (i = obj->interfaces; i; i = i->next) {
+        Interface *iface = i->data;
+
+        if (object_is_type(OBJECT(iface), typename)) {
+            return OBJECT(iface);
+        }
+    }
+
+    /* Check if obj is an interface and its containing object is a direct
+     * ancestor of typename */
+    if (object_is_type(obj, TYPE_INTERFACE)) {
+        Interface *iface = INTERFACE(obj);
+
+        if (object_is_type(iface->obj, typename)) {
+            return iface->obj;
+        }
+    }
+
+    return NULL;
+}
+
+
+static void register_interface(void)
+{
+    static TypeInfo interface_info = {
+        .name = TYPE_INTERFACE,
+        .instance_size = sizeof(Interface),
+        .abstract = true,
+    };
+
+    type_register_static(&interface_info);
+}
+
+device_init(register_interface);
+
+Object *object_dynamic_cast_assert(Object *obj, const char *typename)
+{
+    Object *inst;
+
+    inst = object_dynamic_cast(obj, typename);
+
+    if (!inst) {
+        fprintf(stderr, "Object %p is not an instance of type %s\n",
+                obj, typename);
+        abort();
+    }
+
+    return inst;
+}
+
+ObjectClass *object_class_dynamic_cast(ObjectClass *class,
+                                       const char *typename)
+{
+    TypeImpl *target_type = type_get_by_name(typename);
+    TypeImpl *type = class->type;
+
+    while (type) {
+        if (type == target_type) {
+            return class;
+        }
+
+        type = type_get_parent(type);
+    }
+
+    return NULL;
+}
+
+ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
+                                              const char *typename)
+{
+    ObjectClass *ret = object_class_dynamic_cast(class, typename);
+
+    if (!ret) {
+        fprintf(stderr, "Object %p is not an instance of type %s\n",
+                class, typename);
+        abort();
+    }
+
+    return ret;
+}
+
+const char *object_get_typename(Object *obj)
+{
+    return obj->class->type->name;
+}
+
+ObjectClass *object_get_class(Object *obj)
+{
+    return obj->class;
+}
+
+const char *object_class_get_name(ObjectClass *klass)
+{
+    return klass->type->name;
+}
+
+ObjectClass *object_class_by_name(const char *typename)
+{
+    TypeImpl *type = type_get_by_name(typename);
+
+    if (!type) {
+        return NULL;
+    }
+
+    type_class_init(type);
+
+    return type->class;
+}
+
+typedef struct OCFData
+{
+    void (*fn)(ObjectClass *klass, void *opaque);
+    void *opaque;
+} OCFData;
+
+static void object_class_foreach_tramp(gpointer key, gpointer value,
+                                       gpointer opaque)
+{
+    OCFData *data = opaque;
+    TypeImpl *type = value;
+
+    type_class_init(type);
+
+    data->fn(value, type->class);
+}
+
+void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
+                          void *opaque)
+{
+    OCFData data = { fn, opaque };
+
+    g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);
+}