Commit a31bdae5 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Andreas Färber
Browse files

qom: Add object_new_with_props() / object_new_withpropv() helpers 



It is reasonably common to want to create an object, set a
number of properties, register it in the hierarchy and then
mark it as complete (if a user creatable type). This requires
quite a lot of error prone, verbose, boilerplate code to achieve.

First a pair of functions object_set_props() / object_set_propv()
are added which allow for a list of objects to be set in
one single API call.

Then object_new_with_props() / object_new_with_propv() constructors
are added which simplify the sequence of calls to create an
object, populate properties, register in the object composition
tree and mark the object complete, into a single method call.

Usage would be:

   Error *err = NULL;
   Object *obj;
   obj = object_new_with_propv(TYPE_MEMORY_BACKEND_FILE,
                               object_get_objects_root(),
                               "hostmem0",
                               &err,
                               "share", "yes",
                               "mem-path", "/dev/shm/somefile",
                               "prealloc", "yes",
                               "size", "1048576",
                               NULL);

Note all property values are passed in string form and will
be parsed into their required data types, using normal QOM
semantics for parsing from string format.

Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarAndreas Färber <afaerber@suse.de>
parent bc2256c4

include/qemu/compiler.h

+6 −0
Original line number Diff line number Diff line
@@ -24,6 +24,12 @@ 
#define QEMU_WARN_UNUSED_RESULT

#endif



#if QEMU_GNUC_PREREQ(4, 0)

#define QEMU_SENTINEL __attribute__((sentinel))

#else

#define QEMU_SENTINEL

#endif



#if QEMU_GNUC_PREREQ(4, 3)

#define QEMU_ARTIFICIAL __attribute__((always_inline, artificial))

#else

include/qom/object.h

+128 −0
Original line number Diff line number Diff line
@@ -606,6 +606,134 @@ Object *object_new(const char *typename); 
 */

Object *object_new_with_type(Type type);



/**

 * object_new_with_props:

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

 * @parent: the parent object

 * @id: The unique ID of the object

 * @errp: pointer to error object

 * @...: list of property names and values

 *

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

 * The returned object has a reference count of 1, and will be freed when

 * the last reference is dropped.

 *

 * The @id parameter will be used when registering the object as a

 * child of @parent in the composition tree.

 *

 * The variadic parameters are a list of pairs of (propname, propvalue)

 * strings. The propname of %NULL indicates the end of the property

 * list. If the object implements the user creatable interface, the

 * object will be marked complete once all the properties have been

 * processed.

 *

 * <example>

 *   <title>Creating an object with properties</title>

 *   <programlisting>

 *   Error *err = NULL;

 *   Object *obj;

 *

 *   obj = object_new_with_props(TYPE_MEMORY_BACKEND_FILE,

 *                               object_get_objects_root(),

 *                               "hostmem0",

 *                               &err,

 *                               "share", "yes",

 *                               "mem-path", "/dev/shm/somefile",

 *                               "prealloc", "yes",

 *                               "size", "1048576",

 *                               NULL);

 *

 *   if (!obj) {

 *     g_printerr("Cannot create memory backend: %s\n",

 *                error_get_pretty(err));

 *   }

 *   </programlisting>

 * </example>

 *

 * The returned object will have one stable reference maintained

 * for as long as it is present in the object hierarchy.

 *

 * Returns: The newly allocated, instantiated & initialized object.

 */

Object *object_new_with_props(const char *typename,

                              Object *parent,

                              const char *id,

                              Error **errp,

                              ...) QEMU_SENTINEL;



/**

 * object_new_with_propv:

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

 * @parent: the parent object

 * @id: The unique ID of the object

 * @errp: pointer to error object

 * @vargs: list of property names and values

 *

 * See object_new_with_props() for documentation.

 */

Object *object_new_with_propv(const char *typename,

                              Object *parent,

                              const char *id,

                              Error **errp,

                              va_list vargs);



/**

 * object_set_props:

 * @obj: the object instance to set properties on

 * @errp: pointer to error object

 * @...: list of property names and values

 *

 * This function will set a list of properties on an existing object

 * instance.

 *

 * The variadic parameters are a list of pairs of (propname, propvalue)

 * strings. The propname of %NULL indicates the end of the property

 * list.

 *

 * <example>

 *   <title>Update an object's properties</title>

 *   <programlisting>

 *   Error *err = NULL;

 *   Object *obj = ...get / create object...;

 *

 *   obj = object_set_props(obj,

 *                          &err,

 *                          "share", "yes",

 *                          "mem-path", "/dev/shm/somefile",

 *                          "prealloc", "yes",

 *                          "size", "1048576",

 *                          NULL);

 *

 *   if (!obj) {

 *     g_printerr("Cannot set properties: %s\n",

 *                error_get_pretty(err));

 *   }

 *   </programlisting>

 * </example>

 *

 * The returned object will have one stable reference maintained

 * for as long as it is present in the object hierarchy.

 *

 * Returns: -1 on error, 0 on success

 */

int object_set_props(Object *obj,

                     Error **errp,

                     ...) QEMU_SENTINEL;



/**

 * object_set_propv:

 * @obj: the object instance to set properties on

 * @errp: pointer to error object

 * @vargs: list of property names and values

 *

 * See object_set_props() for documentation.

 *

 * Returns: -1 on error, 0 on success

 */

int object_set_propv(Object *obj,

                     Error **errp,

                     va_list vargs);



/**

 * object_initialize_with_type:

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

qom/object.c

+109 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
 */



#include "qom/object.h"

#include "qom/object_interfaces.h"

#include "qemu-common.h"

#include "qapi/visitor.h"

#include "qapi-visit.h"
@@ -439,6 +440,114 @@ Object *object_new(const char *typename) 
    return object_new_with_type(ti);

}





Object *object_new_with_props(const char *typename,

                              Object *parent,

                              const char *id,

                              Error **errp,

                              ...)

{

    va_list vargs;

    Object *obj;



    va_start(vargs, errp);

    obj = object_new_with_propv(typename, parent, id, errp, vargs);

    va_end(vargs);



    return obj;

}





Object *object_new_with_propv(const char *typename,

                              Object *parent,

                              const char *id,

                              Error **errp,

                              va_list vargs)

{

    Object *obj;

    ObjectClass *klass;

    Error *local_err = NULL;



    klass = object_class_by_name(typename);

    if (!klass) {

        error_setg(errp, "invalid object type: %s", typename);

        return NULL;

    }



    if (object_class_is_abstract(klass)) {

        error_setg(errp, "object type '%s' is abstract", typename);

        return NULL;

    }

    obj = object_new(typename);



    if (object_set_propv(obj, &local_err, vargs) < 0) {

        goto error;

    }



    object_property_add_child(parent, id, obj, &local_err);

    if (local_err) {

        goto error;

    }



    if (object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {

        user_creatable_complete(obj, &local_err);

        if (local_err) {

            object_unparent(obj);

            goto error;

        }

    }



    object_unref(OBJECT(obj));

    return obj;



 error:

    if (local_err) {

        error_propagate(errp, local_err);

    }

    object_unref(obj);

    return NULL;

}





int object_set_props(Object *obj,

                     Error **errp,

                     ...)

{

    va_list vargs;

    int ret;



    va_start(vargs, errp);

    ret = object_set_propv(obj, errp, vargs);

    va_end(vargs);



    return ret;

}





int object_set_propv(Object *obj,

                     Error **errp,

                     va_list vargs)

{

    const char *propname;

    Error *local_err = NULL;



    propname = va_arg(vargs, char *);

    while (propname != NULL) {

        const char *value = va_arg(vargs, char *);



        g_assert(value != NULL);

        object_property_parse(obj, value, propname, &local_err);

        if (local_err) {

            error_propagate(errp, local_err);

            return -1;

        }

        propname = va_arg(vargs, char *);

    }



    return 0;

}





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

{

    if (obj && object_class_dynamic_cast(object_get_class(obj), typename)) {

tests/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ check-qjson 
check-qlist

check-qstring

check-qom-interface

check-qom-proplist

rcutorture

test-aio

test-bitops

tests/Makefile

+4 −1
Original line number Diff line number Diff line
@@ -68,6 +68,8 @@ check-unit-y += tests/test-bitops$(EXESUF) 
check-unit-$(CONFIG_HAS_GLIB_SUBPROCESS_TESTS) += tests/test-qdev-global-props$(EXESUF)

check-unit-y += tests/check-qom-interface$(EXESUF)

gcov-files-check-qom-interface-y = qom/object.c

check-unit-y += tests/check-qom-proplist$(EXESUF)

gcov-files-check-qom-proplist-y = qom/object.c

check-unit-y += tests/test-qemu-opts$(EXESUF)

gcov-files-test-qemu-opts-y = qom/test-qemu-opts.c

check-unit-y += tests/test-write-threshold$(EXESUF)
@@ -267,7 +269,7 @@ test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o \ 


$(test-obj-y): QEMU_INCLUDES += -Itests

QEMU_CFLAGS += -I$(SRC_PATH)/tests

qom-core-obj = qom/object.o qom/qom-qobject.o qom/container.o

qom-core-obj = qom/object.o qom/qom-qobject.o qom/container.o qom/object_interfaces.o



tests/check-qint$(EXESUF): tests/check-qint.o libqemuutil.a

tests/check-qstring$(EXESUF): tests/check-qstring.o libqemuutil.a
@@ -276,6 +278,7 @@ tests/check-qlist$(EXESUF): tests/check-qlist.o libqemuutil.a 
tests/check-qfloat$(EXESUF): tests/check-qfloat.o libqemuutil.a

tests/check-qjson$(EXESUF): tests/check-qjson.o libqemuutil.a libqemustub.a

tests/check-qom-interface$(EXESUF): tests/check-qom-interface.o $(qom-core-obj) libqemuutil.a libqemustub.a

tests/check-qom-proplist$(EXESUF): tests/check-qom-proplist.o $(qom-core-obj) libqemuutil.a libqemustub.a

tests/test-coroutine$(EXESUF): tests/test-coroutine.o $(block-obj-y) libqemuutil.a libqemustub.a

tests/test-aio$(EXESUF): tests/test-aio.o $(block-obj-y) libqemuutil.a libqemustub.a

tests/test-rfifolock$(EXESUF): tests/test-rfifolock.o libqemuutil.a libqemustub.a