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/*

 * 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.

 *

 */

#ifndef QEMU_OBJECT_H

#define QEMU_OBJECT_H

#include <glib.h>

#include <stdint.h>

#include <stdbool.h>

#include "qemu/queue.h"

struct Visitor;

struct Error;

struct TypeImpl;

typedef struct TypeImpl *Type;

typedef struct ObjectClass ObjectClass;

typedef struct Object Object;

typedef struct TypeInfo TypeInfo;

typedef struct InterfaceClass InterfaceClass;

typedef struct InterfaceInfo InterfaceInfo;

#define TYPE_OBJECT "object"

/**

 * SECTION:object.h

 * @title:Base Object Type System

 * @short_description: interfaces for creating new types and objects

 *

 * The QEMU Object Model provides a framework for registering user creatable

 * types and instantiating objects from those types.  QOM provides the following

 * features:

 *

 *  - System for dynamically registering types

 *  - Support for single-inheritance of types

 *  - Multiple inheritance of stateless interfaces

 *

 * <example>

 *   <title>Creating a minimal type</title>

 *   <programlisting>

 * #include "qdev.h"

 *

 * #define TYPE_MY_DEVICE "my-device"

 *

 * // No new virtual functions: we can reuse the typedef for the

 * // superclass.

 * typedef DeviceClass MyDeviceClass;

 * typedef struct MyDevice

 * {

 *     DeviceState parent;

 *

 *     int reg0, reg1, reg2;

 * } MyDevice;

 *

 * static TypeInfo my_device_info = {

 *     .name = TYPE_MY_DEVICE,

 *     .parent = TYPE_DEVICE,

 *     .instance_size = sizeof(MyDevice),

 * };

 *

 * static void my_device_register_types(void)

 * {

 *     type_register_static(&my_device_info);

 * }

 *

 * type_init(my_device_register_types)

 *   </programlisting>

 * </example>

 *

 * In the above example, we create a simple type that is described by #TypeInfo.

 * #TypeInfo describes information about the type including what it inherits

 * from, the instance and class size, and constructor/destructor hooks.

 *

 * Every type has an #ObjectClass associated with it.  #ObjectClass derivatives

 * are instantiated dynamically but there is only ever one instance for any

 * given type.  The #ObjectClass typically holds a table of function pointers

 * for the virtual methods implemented by this type.

 *

 * Using object_new(), a new #Object derivative will be instantiated.  You can

 * cast an #Object to a subclass (or base-class) type using

 * object_dynamic_cast().  You typically want to define macro wrappers around

 * OBJECT_CHECK() and OBJECT_CLASS_CHECK() to make it easier to convert to a

 * specific type:

 *

 * <example>

 *   <title>Typecasting macros</title>

 *   <programlisting>

 *    #define MY_DEVICE_GET_CLASS(obj) \

 *       OBJECT_GET_CLASS(MyDeviceClass, obj, TYPE_MY_DEVICE)

 *    #define MY_DEVICE_CLASS(klass) \

 *       OBJECT_CLASS_CHECK(MyDeviceClass, klass, TYPE_MY_DEVICE)

 *    #define MY_DEVICE(obj) \

 *       OBJECT_CHECK(MyDevice, obj, TYPE_MY_DEVICE)

 *   </programlisting>

 * </example>

 *

 * # Class Initialization #

 *

 * Before an object is initialized, the class for the object must be

 * initialized.  There is only one class object for all instance objects

 * that is created lazily.

 *

 * Classes are initialized by first initializing any parent classes (if

 * necessary).  After the parent class object has initialized, it will be

 * copied into the current class object and any additional storage in the

 * class object is zero filled.

 *

 * The effect of this is that classes automatically inherit any virtual

 * function pointers that the parent class has already initialized.  All

 * other fields will be zero filled.

 *

 * Once all of the parent classes have been initialized, #TypeInfo::class_init

 * is called to let the class being instantiated provide default initialize for

 * its virtual functions.  Here is how the above example might be modified

 * to introduce an overridden virtual function:

 *

 * <example>

 *   <title>Overriding a virtual function</title>

 *   <programlisting>

 * #include "qdev.h"

 *

 * void my_device_class_init(ObjectClass *klass, void *class_data)

 * {

 *     DeviceClass *dc = DEVICE_CLASS(klass);

 *     dc->reset = my_device_reset;

 * }

 *

 * static TypeInfo my_device_info = {

 *     .name = TYPE_MY_DEVICE,

 *     .parent = TYPE_DEVICE,

 *     .instance_size = sizeof(MyDevice),

 *     .class_init = my_device_class_init,

 * };

 *   </programlisting>

 * </example>

 *

 * Introducing new virtual functions requires a class to define its own

 * struct and to add a .class_size member to the TypeInfo.  Each function

 * will also have a wrapper to call it easily:

 *

 * <example>

 *   <title>Defining an abstract class</title>

 *   <programlisting>

 * #include "qdev.h"

 *

 * typedef struct MyDeviceClass

 * {

 *     DeviceClass parent;

 *

 *     void (*frobnicate) (MyDevice *obj);

 * } MyDeviceClass;

 *

 * static TypeInfo my_device_info = {

 *     .name = TYPE_MY_DEVICE,

 *     .parent = TYPE_DEVICE,

 *     .instance_size = sizeof(MyDevice),

 *     .abstract = true, // or set a default in my_device_class_init

 *     .class_size = sizeof(MyDeviceClass),

 * };

 *

 * void my_device_frobnicate(MyDevice *obj)

 * {

 *     MyDeviceClass *klass = MY_DEVICE_GET_CLASS(obj);

 *

 *     klass->frobnicate(obj);

 * }

 *   </programlisting>

 * </example>

 *

 * # Interfaces #

 *

 * Interfaces allow a limited form of multiple inheritance.  Instances are

 * similar to normal types except for the fact that are only defined by

 * their classes and never carry any state.  You can dynamically cast an object

 * to one of its #Interface types and vice versa.

 */

/**

 * ObjectPropertyAccessor:

 * @obj: the object that owns the property

 * @v: the visitor that contains the property data

 * @opaque: the object property opaque

 * @name: the name of the property

 * @errp: a pointer to an Error that is filled if getting/setting fails.

 *

 * Called when trying to get/set a property.

 */

typedef void (ObjectPropertyAccessor)(Object *obj,

                                      struct Visitor *v,

                                      void *opaque,

                                      const char *name,

                                      struct Error **errp);

/**

 * ObjectPropertyRelease:

 * @obj: the object that owns the property

 * @name: the name of the property

 * @opaque: the opaque registered with the property

 *

 * Called when a property is removed from a object.

 */

typedef void (ObjectPropertyRelease)(Object *obj,

                                     const char *name,

                                     void *opaque);

typedef struct ObjectProperty

{

    gchar *name;

    gchar *type;

    ObjectPropertyAccessor *get;

    ObjectPropertyAccessor *set;

    ObjectPropertyRelease *release;

    void *opaque;

    QTAILQ_ENTRY(ObjectProperty) node;

} ObjectProperty;

/**

 * ObjectUnparent:

 * @obj: the object that is being removed from the composition tree

 *

 * Called when an object is being removed from the QOM composition tree.

 * The function should remove any backlinks from children objects to @obj.

 */

typedef void (ObjectUnparent)(Object *obj);

/**

 * ObjectFree:

 * @obj: the object being freed

 *

 * Called when an object's last reference is removed.

 */

typedef void (ObjectFree)(void *obj);

/**

 * ObjectClass:

 *

 * The base for all classes.  The only thing that #ObjectClass contains is an

 * integer type handle.

 */

struct ObjectClass

{

    /*< private >*/

    Type type;

    GSList *interfaces;

    ObjectUnparent *unparent;

};

/**

 * Object:

 *

 * The base for all objects.  The first member of this object is a pointer to

 * a #ObjectClass.  Since C guarantees that the first member of a structure

 * always begins at byte 0 of that structure, as long as any sub-object places

 * its parent as the first member, we can cast directly to a #Object.

 *

 * As a result, #Object contains a reference to the objects type as its

 * first member.  This allows identification of the real type of the object at

 * run time.

 *

 * #Object also contains a list of #Interfaces that this object

 * implements.

 */

struct Object

{

    /*< private >*/

    ObjectClass *class;

    ObjectFree *free;

    QTAILQ_HEAD(, ObjectProperty) properties;

    uint32_t ref;

    Object *parent;

};

/**

 * TypeInfo:

 * @name: The name of the type.

 * @parent: The name of the parent type.

 * @instance_size: The size of the object (derivative of #Object).  If

 *   @instance_size is 0, then the size of the object will be the size of the

 *   parent object.

 * @instance_init: This function is called to initialize an object.  The parent

 *   class will have already been initialized so the type is only responsible

 *   for initializing its own members.

 * @instance_finalize: This function is called during object destruction.  This

 *   is called before the parent @instance_finalize function has been called.

 *   An object should only free the members that are unique to its type in this

 *   function.

 * @abstract: If this field is true, then the class is considered abstract and

 *   cannot be directly instantiated.

 * @class_size: The size of the class object (derivative of #ObjectClass)

 *   for this object.  If @class_size is 0, then the size of the class will be

 *   assumed to be the size of the parent class.  This allows a type to avoid

 *   implementing an explicit class type if they are not adding additional

 *   virtual functions.

 * @class_init: This function is called after all parent class initialization

 *   has occurred to allow a class to set its default virtual method pointers.

 *   This is also the function to use to override virtual methods from a parent

 *   class.

 * @class_base_init: This function is called for all base classes after all

 *   parent class initialization has occurred, but before the class itself

 *   is initialized.  This is the function to use to undo the effects of

 *   memcpy from the parent class to the descendents.

 * @class_finalize: This function is called during class destruction and is

 *   meant to release and dynamic parameters allocated by @class_init.

 * @class_data: Data to pass to the @class_init, @class_base_init and

 *   @class_finalize functions.  This can be useful when building dynamic

 *   classes.

 * @interfaces: The list of interfaces associated with this type.  This

 *   should point to a static array that's terminated with a zero filled

 *   element.

 */

struct TypeInfo

{

    const char *name;

    const char *parent;

    size_t instance_size;

    void (*instance_init)(Object *obj);

    void (*instance_finalize)(Object *obj);

    bool abstract;

    size_t class_size;

    void (*class_init)(ObjectClass *klass, void *data);

    void (*class_base_init)(ObjectClass *klass, void *data);

    void (*class_finalize)(ObjectClass *klass, void *data);

    void *class_data;

    InterfaceInfo *interfaces;

};

/**

 * OBJECT:

 * @obj: A derivative of #Object

 *

 * Converts an object to a #Object.  Since all objects are #Objects,

 * this function will always succeed.

 */

#define OBJECT(obj) \

    ((Object *)(obj))

/**

 * OBJECT_CLASS:

 * @class: A derivative of #ObjectClass.

 *

 * Converts a class to an #ObjectClass.  Since all objects are #Objects,

 * this function will always succeed.

 */

#define OBJECT_CLASS(class) \

    ((ObjectClass *)(class))

/**

 * OBJECT_CHECK:

 * @type: The C type to use for the return value.

 * @obj: A derivative of @type to cast.

 * @name: The QOM typename of @type

 *

 * A type safe version of @object_dynamic_cast_assert.  Typically each class

 * will define a macro based on this type to perform type safe dynamic_casts to

 * this object type.

 *

 * If an invalid object is passed to this function, a run time assert will be

 * generated.

 */

#define OBJECT_CHECK(type, obj, name) \

    ((type *)object_dynamic_cast_assert(OBJECT(obj), (name)))

/**

 * OBJECT_CLASS_CHECK:

 * @class: The C type to use for the return value.

 * @obj: A derivative of @type to cast.

 * @name: the QOM typename of @class.

 *

 * A type safe version of @object_class_dynamic_cast_assert.  This macro is

 * typically wrapped by each type to perform type safe casts of a class to a

 * specific class type.

 */

#define OBJECT_CLASS_CHECK(class, obj, name) \

    ((class *)object_class_dynamic_cast_assert(OBJECT_CLASS(obj), (name)))

/**

 * OBJECT_GET_CLASS:

 * @class: The C type to use for the return value.

 * @obj: The object to obtain the class for.

 * @name: The QOM typename of @obj.

 *

 * This function will return a specific class for a given object.  Its generally

 * used by each type to provide a type safe macro to get a specific class type

 * from an object.

 */

#define OBJECT_GET_CLASS(class, obj, name) \

    OBJECT_CLASS_CHECK(class, object_get_class(OBJECT(obj)), name)

/**

 * InterfaceInfo:

 * @type: The name of the interface.

 *

 * The information associated with an interface.

 */

struct InterfaceInfo {

    const char *type;

};

/**

 * InterfaceClass:

 * @parent_class: the base class

 *

 * The class for all interfaces.  Subclasses of this class should only add

 * virtual methods.

 */

struct InterfaceClass

{

    ObjectClass parent_class;

    /*< private >*/

    ObjectClass *concrete_class;

};

#define TYPE_INTERFACE "interface"

/**

 * INTERFACE_CLASS:

 * @klass: class to cast from

 * Returns: An #InterfaceClass or raise an error if cast is invalid

 */

#define INTERFACE_CLASS(klass) \

    OBJECT_CLASS_CHECK(InterfaceClass, klass, TYPE_INTERFACE)

/**

 * INTERFACE_CHECK:

 * @interface: the type to return

 * @obj: the object to convert to an interface

 * @name: the interface type name

 *

 * Returns: @obj casted to @interface if cast is valid, otherwise raise error.

 */

#define INTERFACE_CHECK(interface, obj, name) \

    ((interface *)object_dynamic_cast_assert(OBJECT((obj)), (name)))

/**

 * object_new:

 * @typename: The name of the type of the object to instantiate.

 *

 * This function will initialize a new object using heap allocated memory.  This

 * function should be paired with object_delete() to free the resources

 * associated with the object.

 *

 * Returns: The newly allocated and instantiated object.

 */

Object *object_new(const char *typename);

/**

 * object_new_with_type:

 * @type: The type of the object to instantiate.

 *

 * This function will initialize a new object using heap allocated memory.  This

 * function should be paired with object_delete() to free the resources

 * associated with the object.

 *

 * Returns: The newly allocated and instantiated object.

 */

Object *object_new_with_type(Type type);

/**

 * object_delete:

 * @obj: The object to free.

 *

 * Finalize an object and then free the memory associated with it.  This should

 * be paired with object_new() to free the resources associated with an object.

 */

void object_delete(Object *obj);

/**

 * object_initialize_with_type:

 * @obj: A pointer to the memory to be used for the object.

 * @type: The type of the object to instantiate.

 *

 * This function will initialize an object.  The memory for the object should

 * have already been allocated.

 */

void object_initialize_with_type(void *data, Type type);

/**

 * object_initialize:

 * @obj: A pointer to the memory to be used for the object.

 * @typename: The name of the type of the object to instantiate.

 *

 * This function will initialize an object.  The memory for the object should

 * have already been allocated.

 */

void object_initialize(void *obj, const char *typename);

/**

 * object_dynamic_cast:

 * @obj: The object to cast.

 * @typename: The @typename to cast to.

 *

 * This function will determine if @obj is-a @typename.  @obj can refer to an

 * object or an interface associated with an object.

 *

 * Returns: This function returns @obj on success or #NULL on failure.

 */

Object *object_dynamic_cast(Object *obj, const char *typename);

/**

 * object_dynamic_cast_assert:

 *

 * See object_dynamic_cast() for a description of the parameters of this

 * function.  The only difference in behavior is that this function asserts

 * instead of returning #NULL on failure.

 */

Object *object_dynamic_cast_assert(Object *obj, const char *typename);

/**

 * object_get_class:

 * @obj: A derivative of #Object

 *

 * Returns: The #ObjectClass of the type associated with @obj.

 */

ObjectClass *object_get_class(Object *obj);

/**

 * object_get_typename:

 * @obj: A derivative of #Object.

 *

 * Returns: The QOM typename of @obj.

 */

const char *object_get_typename(Object *obj);

/**

 * type_register_static:

 * @info: The #TypeInfo of the new type.

 *

 * @info and all of the strings it points to should exist for the life time

 * that the type is registered.

 *

 * Returns: 0 on failure, the new #Type on success.

 */

Type type_register_static(const TypeInfo *info);

/**

 * type_register:

 * @info: The #TypeInfo of the new type

 *

 * Unlike type_register_static(), this call does not require @info or its

 * string members to continue to exist after the call returns.

 *

 * Returns: 0 on failure, the new #Type on success.

 */

Type type_register(const TypeInfo *info);

/**

 * object_class_dynamic_cast_assert:

 * @klass: The #ObjectClass to attempt to cast.

 * @typename: The QOM typename of the class to cast to.

 *

 * Returns: This function always returns @klass and asserts on failure.

 */

ObjectClass *object_class_dynamic_cast_assert(ObjectClass *klass,

                                              const char *typename);

ObjectClass *object_class_dynamic_cast(ObjectClass *klass,

                                       const char *typename);

/**

 * object_class_get_parent:

 * @klass: The class to obtain the parent for.

 *

 * Returns: The parent for @klass or %NULL if none.

 */

ObjectClass *object_class_get_parent(ObjectClass *klass);

/**

 * object_class_get_name:

 * @klass: The class to obtain the QOM typename for.

 *

 * Returns: The QOM typename for @klass.

 */

const char *object_class_get_name(ObjectClass *klass);

/**

 * object_class_by_name:

 * @typename: The QOM typename to obtain the class for.

 *

 * Returns: The class for @typename or %NULL if not found.

 */

ObjectClass *object_class_by_name(const char *typename);

void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),

                          const char *implements_type, bool include_abstract,

                          void *opaque);

/**

 * object_class_get_list:

 * @implements_type: The type to filter for, including its derivatives.

 * @include_abstract: Whether to include abstract classes.

 *

 * Returns: A singly-linked list of the classes in reverse hashtable order.

 */

GSList *object_class_get_list(const char *implements_type,

                              bool include_abstract);

/**

 * object_ref:

 * @obj: the object

 *

 * Increase the reference count of a object.  A object cannot be freed as long

 * as its reference count is greater than zero.

 */

void object_ref(Object *obj);

/**

 * qdef_unref:

 * @obj: the object

 *

 * Decrease the reference count of a object.  A object cannot be freed as long

 * as its reference count is greater than zero.

 */

void object_unref(Object *obj);

/**

 * object_property_add:

 * @obj: the object to add a property to

 * @name: the name of the property.  This can contain any character except for

 *  a forward slash.  In general, you should use hyphens '-' instead of

 *  underscores '_' when naming properties.

 * @type: the type name of the property.  This namespace is pretty loosely

 *   defined.  Sub namespaces are constructed by using a prefix and then

 *   to angle brackets.  For instance, the type 'virtio-net-pci' in the

 *   'link' namespace would be 'link<virtio-net-pci>'.

 * @get: The getter to be called to read a property.  If this is NULL, then

 *   the property cannot be read.

 * @set: the setter to be called to write a property.  If this is NULL,

 *   then the property cannot be written.

 * @release: called when the property is removed from the object.  This is

 *   meant to allow a property to free its opaque upon object

 *   destruction.  This may be NULL.

 * @opaque: an opaque pointer to pass to the callbacks for the property

 * @errp: returns an error if this function fails

 */

void object_property_add(Object *obj, const char *name, const char *type,

                         ObjectPropertyAccessor *get,

                         ObjectPropertyAccessor *set,

                         ObjectPropertyRelease *release,

                         void *opaque, struct Error **errp);

void object_property_del(Object *obj, const char *name, struct Error **errp);

/**

 * object_property_find:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Look up a property for an object and return its #ObjectProperty if found.

 */

ObjectProperty *object_property_find(Object *obj, const char *name,

                                     struct Error **errp);

void object_unparent(Object *obj);

/**

 * object_property_get:

 * @obj: the object

 * @v: the visitor that will receive the property value.  This should be an

 *   Output visitor and the data will be written with @name as the name.

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Reads a property from a object.

 */

void object_property_get(Object *obj, struct Visitor *v, const char *name,

                         struct Error **errp);

/**

 * object_property_set_str:

 * @value: the value to be written to the property

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Writes a string value to a property.

 */

void object_property_set_str(Object *obj, const char *value,

                             const char *name, struct Error **errp);

/**

 * object_property_get_str:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns: the value of the property, converted to a C string, or NULL if

 * an error occurs (including when the property value is not a string).

 * The caller should free the string.

 */

char *object_property_get_str(Object *obj, const char *name,

                              struct Error **errp);

/**

 * object_property_set_link:

 * @value: the value to be written to the property

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Writes an object's canonical path to a property.

 */

void object_property_set_link(Object *obj, Object *value,

                              const char *name, struct Error **errp);

/**

 * object_property_get_link:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns: the value of the property, resolved from a path to an Object,

 * or NULL if an error occurs (including when the property value is not a

 * string or not a valid object path).

 */

Object *object_property_get_link(Object *obj, const char *name,

                                 struct Error **errp);

/**

 * object_property_set_bool:

 * @value: the value to be written to the property

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Writes a bool value to a property.

 */

void object_property_set_bool(Object *obj, bool value,

                              const char *name, struct Error **errp);

/**

 * object_property_get_bool:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns: the value of the property, converted to a boolean, or NULL if

 * an error occurs (including when the property value is not a bool).

 */

bool object_property_get_bool(Object *obj, const char *name,

                              struct Error **errp);

/**

 * object_property_set_int:

 * @value: the value to be written to the property

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Writes an integer value to a property.

 */

void object_property_set_int(Object *obj, int64_t value,

                             const char *name, struct Error **errp);

/**

 * object_property_get_int:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns: the value of the property, converted to an integer, or NULL if

 * an error occurs (including when the property value is not an integer).

 */

int64_t object_property_get_int(Object *obj, const char *name,

                                struct Error **errp);

/**

 * object_property_set:

 * @obj: the object

 * @v: the visitor that will be used to write the property value.  This should

 *   be an Input visitor and the data will be first read with @name as the

 *   name and then written as the property value.

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Writes a property to a object.

 */

void object_property_set(Object *obj, struct Visitor *v, const char *name,

                         struct Error **errp);

/**

 * object_property_parse:

 * @obj: the object

 * @string: the string that will be used to parse the property value.

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Parses a string and writes the result into a property of an object.

 */

void object_property_parse(Object *obj, const char *string,

                           const char *name, struct Error **errp);

/**

 * object_property_print:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns a string representation of the value of the property.  The

 * caller shall free the string.

 */

char *object_property_print(Object *obj, const char *name,

                            struct Error **errp);

/**

 * object_property_get_type:

 * @obj: the object

 * @name: the name of the property

 * @errp: returns an error if this function fails

 *

 * Returns:  The type name of the property.

 */

const char *object_property_get_type(Object *obj, const char *name,

                                     struct Error **errp);

/**

 * object_get_root:

 *

 * Returns: the root object of the composition tree

 */

Object *object_get_root(void);

/**

 * object_get_canonical_path:

 *

 * Returns: The canonical path for a object.  This is the path within the

 * composition tree starting from the root.

 */

gchar *object_get_canonical_path(Object *obj);

/**

 * object_resolve_path:

 * @path: the path to resolve

 * @ambiguous: returns true if the path resolution failed because of an

 *   ambiguous match

 *

 * There are two types of supported paths--absolute paths and partial paths.

 * 

 * Absolute paths are derived from the root object and can follow child<> or

 * link<> properties.  Since they can follow link<> properties, they can be

 * arbitrarily long.  Absolute paths look like absolute filenames and are

 * prefixed with a leading slash.

 * 

 * Partial paths look like relative filenames.  They do not begin with a

 * prefix.  The matching rules for partial paths are subtle but designed to make

 * specifying objects easy.  At each level of the composition tree, the partial

 * path is matched as an absolute path.  The first match is not returned.  At

 * least two matches are searched for.  A successful result is only returned if

 * only one match is found.  If more than one match is found, a flag is

 * returned to indicate that the match was ambiguous.

 *

 * Returns: The matched object or NULL on path lookup failure.

 */

Object *object_resolve_path(const char *path, bool *ambiguous);

/**

 * object_resolve_path_type:

 * @path: the path to resolve

 * @typename: the type to look for.

 * @ambiguous: returns true if the path resolution failed because of an

 *   ambiguous match

 *

 * This is similar to object_resolve_path.  However, when looking for a

 * partial path only matches that implement the given type are considered.

 * This restricts the search and avoids spuriously flagging matches as

 * ambiguous.

 *

 * For both partial and absolute paths, the return value goes through

 * a dynamic cast to @typename.  This is important if either the link,

 * or the typename itself are of interface types.

 *

 * Returns: The matched object or NULL on path lookup failure.

 */

Object *object_resolve_path_type(const char *path, const char *typename,

                                 bool *ambiguous);

/**

 * object_resolve_path_component:

 * @parent: the object in which to resolve the path

 * @part: the component to resolve.

 *

 * This is similar to object_resolve_path with an absolute path, but it

 * only resolves one element (@part) and takes the others from @parent.

 *

 * Returns: The resolved object or NULL on path lookup failure.

 */

Object *object_resolve_path_component(Object *parent, gchar *part);

/**

 * object_property_add_child:

 * @obj: the object to add a property to

 * @name: the name of the property

 * @child: the child object

 * @errp: if an error occurs, a pointer to an area to store the area

 *

 * Child properties form the composition tree.  All objects need to be a child

 * of another object.  Objects can only be a child of one object.

 *

 * There is no way for a child to determine what its parent is.  It is not

 * a bidirectional relationship.  This is by design.

 *

 * The value of a child property as a C string will be the child object's

 * canonical path. It can be retrieved using object_property_get_str().

 * The child object itself can be retrieved using object_property_get_link().

 */

void object_property_add_child(Object *obj, const char *name,

                               Object *child, struct Error **errp);

/**

 * object_property_add_link:

 * @obj: the object to add a property to

 * @name: the name of the property

 * @type: the qobj type of the link

 * @child: a pointer to where the link object reference is stored

 * @errp: if an error occurs, a pointer to an area to store the area

 *

 * Links establish relationships between objects.  Links are unidirectional

 * although two links can be combined to form a bidirectional relationship

 * between objects.

 *

 * Links form the graph in the object model.

 */

void object_property_add_link(Object *obj, const char *name,

                              const char *type, Object **child,

                              struct Error **errp);

/**

 * object_property_add_str:

 * @obj: the object to add a property to

 * @name: the name of the property

 * @get: the getter or NULL if the property is write-only.  This function must

 *   return a string to be freed by g_free().

 * @set: the setter or NULL if the property is read-only

 * @errp: if an error occurs, a pointer to an area to store the error

 *

 * Add a string property using getters/setters.  This function will add a

 * property of type 'string'.

 */

void object_property_add_str(Object *obj, const char *name,

                             char *(*get)(Object *, struct Error **),

                             void (*set)(Object *, const char *, struct Error **),

                             struct Error **errp);

/**

 * object_property_add_bool:

 * @obj: the object to add a property to

 * @name: the name of the property

 * @get: the getter or NULL if the property is write-only.

 * @set: the setter or NULL if the property is read-only

 * @errp: if an error occurs, a pointer to an area to store the error

 *

 * Add a bool property using getters/setters.  This function will add a

 * property of type 'bool'.

 */

void object_property_add_bool(Object *obj, const char *name,

                              bool (*get)(Object *, struct Error **),

                              void (*set)(Object *, bool, struct Error **),

                              struct Error **errp);

/**

 * object_child_foreach:

 * @obj: the object whose children will be navigated

 * @fn: the iterator function to be called

 * @opaque: an opaque value that will be passed to the iterator

 *

 * Call @fn passing each child of @obj and @opaque to it, until @fn returns

 * non-zero.

 *

 * Returns: The last value returned by @fn, or 0 if there is no child.

 */

int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),

                         void *opaque);

/**

 * container_get:

 * @root: root of the #path, e.g., object_get_root()

 * @path: path to the container

 *

 * Return a container object whose path is @path.  Create more containers

 * along the path if necessary.

 *

 * Returns: the container object.

 */

Object *container_get(Object *root, const char *path);

#endif