qom/object.c

   1 /*
   2  * QEMU Object Model
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/object.h"
  14 #include "qemu-common.h"
  15 #include "qapi/qapi-visit-core.h"
  16 #include "qapi/string-input-visitor.h"
  17 #include "qapi/string-output-visitor.h"
  18
  19 /* TODO: replace QObject with a simpler visitor to avoid a dependency
  20  * of the QOM core on QObject?  */
  21 #include "qemu/qom-qobject.h"
  22 #include "qobject.h"
  23 #include "qbool.h"
  24 #include "qint.h"
  25 #include "qstring.h"
  26
  27 #define MAX_INTERFACES 32
  28
  29 typedef struct InterfaceImpl InterfaceImpl;
  30 typedef struct TypeImpl TypeImpl;
  31
  32 struct InterfaceImpl
  33 {
  34     const char *parent;
  35     void (*interface_initfn)(ObjectClass *class, void *data);
  36     TypeImpl *type;
  37 };
  38
  39 struct TypeImpl
  40 {
  41     const char *name;
  42
  43     size_t class_size;
  44
  45     size_t instance_size;
  46
  47     void (*class_init)(ObjectClass *klass, void *data);
  48     void (*class_finalize)(ObjectClass *klass, void *data);
  49
  50     void *class_data;
  51
  52     void (*instance_init)(Object *obj);
  53     void (*instance_finalize)(Object *obj);
  54
  55     bool abstract;
  56
  57     const char *parent;
  58     TypeImpl *parent_type;
  59
  60     ObjectClass *class;
  61
  62     int num_interfaces;
  63     InterfaceImpl interfaces[MAX_INTERFACES];
  64 };
  65
  66 typedef struct Interface
  67 {
  68     Object parent;
  69     Object *obj;
  70 } Interface;
  71
  72 #define INTERFACE(obj) OBJECT_CHECK(Interface, obj, TYPE_INTERFACE)
  73
  74 static Type type_interface;
  75
  76 static GHashTable *type_table_get(void)
  77 {
  78     static GHashTable *type_table;
  79
  80     if (type_table == NULL) {
  81         type_table = g_hash_table_new(g_str_hash, g_str_equal);
  82     }
  83
  84     return type_table;
  85 }
  86
  87 static void type_table_add(TypeImpl *ti)
  88 {
  89     g_hash_table_insert(type_table_get(), (void *)ti->name, ti);
  90 }
  91
  92 static TypeImpl *type_table_lookup(const char *name)
  93 {
  94     return g_hash_table_lookup(type_table_get(), name);
  95 }
  96
  97 TypeImpl *type_register(const TypeInfo *info)
  98 {
  99     TypeImpl *ti = g_malloc0(sizeof(*ti));
 100
 101     g_assert(info->name != NULL);
 102
 103     if (type_table_lookup(info->name) != NULL) {
 104         fprintf(stderr, "Registering `%s' which already exists\n", info->name);
 105         abort();
 106     }
 107
 108     ti->name = g_strdup(info->name);
 109     ti->parent = g_strdup(info->parent);
 110
 111     ti->class_size = info->class_size;
 112     ti->instance_size = info->instance_size;
 113
 114     ti->class_init = info->class_init;
 115     ti->class_finalize = info->class_finalize;
 116     ti->class_data = info->class_data;
 117
 118     ti->instance_init = info->instance_init;
 119     ti->instance_finalize = info->instance_finalize;
 120
 121     ti->abstract = info->abstract;
 122
 123     if (info->interfaces) {
 124         int i;
 125
 126         for (i = 0; info->interfaces[i].type; i++) {
 127             ti->interfaces[i].parent = info->interfaces[i].type;
 128             ti->interfaces[i].interface_initfn = info->interfaces[i].interface_initfn;
 129             ti->num_interfaces++;
 130         }
 131     }
 132
 133     type_table_add(ti);
 134
 135     return ti;
 136 }
 137
 138 TypeImpl *type_register_static(const TypeInfo *info)
 139 {
 140     return type_register(info);
 141 }
 142
 143 static TypeImpl *type_get_by_name(const char *name)
 144 {
 145     if (name == NULL) {
 146         return NULL;
 147     }
 148
 149     return type_table_lookup(name);
 150 }
 151
 152 static TypeImpl *type_get_parent(TypeImpl *type)
 153 {
 154     if (!type->parent_type && type->parent) {
 155         type->parent_type = type_get_by_name(type->parent);
 156         g_assert(type->parent_type != NULL);
 157     }
 158
 159     return type->parent_type;
 160 }
 161
 162 static bool type_has_parent(TypeImpl *type)
 163 {
 164     return (type->parent != NULL);
 165 }
 166
 167 static size_t type_class_get_size(TypeImpl *ti)
 168 {
 169     if (ti->class_size) {
 170         return ti->class_size;
 171     }
 172
 173     if (type_has_parent(ti)) {
 174         return type_class_get_size(type_get_parent(ti));
 175     }
 176
 177     return sizeof(ObjectClass);
 178 }
 179
 180 static size_t type_object_get_size(TypeImpl *ti)
 181 {
 182     if (ti->instance_size) {
 183         return ti->instance_size;
 184     }
 185
 186     if (type_has_parent(ti)) {
 187         return type_object_get_size(type_get_parent(ti));
 188     }
 189
 190     return 0;
 191 }
 192
 193 static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)
 194 {
 195     TypeInfo info = {
 196         .instance_size = sizeof(Interface),
 197         .parent = iface->parent,
 198         .class_size = sizeof(InterfaceClass),
 199         .class_init = iface->interface_initfn,
 200         .abstract = true,
 201     };
 202     char *name = g_strdup_printf("<%s::%s>", ti->name, iface->parent);
 203
 204     info.name = name;
 205     iface->type = type_register(&info);
 206     g_free(name);
 207 }
 208
 209 static void type_initialize(TypeImpl *ti)
 210 {
 211     size_t class_size = sizeof(ObjectClass);
 212     int i;
 213
 214     if (ti->class) {
 215         return;
 216     }
 217
 218     ti->class_size = type_class_get_size(ti);
 219     ti->instance_size = type_object_get_size(ti);
 220
 221     ti->class = g_malloc0(ti->class_size);
 222     ti->class->type = ti;
 223
 224     if (type_has_parent(ti)) {
 225         TypeImpl *parent = type_get_parent(ti);
 226
 227         type_initialize(parent);
 228
 229         class_size = parent->class_size;
 230         g_assert(parent->class_size <= ti->class_size);
 231
 232         memcpy((void *)ti->class + sizeof(ObjectClass),
 233                (void *)parent->class + sizeof(ObjectClass),
 234                parent->class_size - sizeof(ObjectClass));
 235     }
 236
 237     memset((void *)ti->class + class_size, 0, ti->class_size - class_size);
 238
 239     for (i = 0; i < ti->num_interfaces; i++) {
 240         type_class_interface_init(ti, &ti->interfaces[i]);
 241     }
 242
 243     if (ti->class_init) {
 244         ti->class_init(ti->class, ti->class_data);
 245     }
 246 }
 247
 248 static void object_interface_init(Object *obj, InterfaceImpl *iface)
 249 {
 250     TypeImpl *ti = iface->type;
 251     Interface *iface_obj;
 252
 253     iface_obj = INTERFACE(object_new(ti->name));
 254     iface_obj->obj = obj;
 255
 256     obj->interfaces = g_slist_prepend(obj->interfaces, iface_obj);
 257 }
 258
 259 static void object_init_with_type(Object *obj, TypeImpl *ti)
 260 {
 261     int i;
 262
 263     if (type_has_parent(ti)) {
 264         object_init_with_type(obj, type_get_parent(ti));
 265     }
 266
 267     for (i = 0; i < ti->num_interfaces; i++) {
 268         object_interface_init(obj, &ti->interfaces[i]);
 269     }
 270
 271     if (ti->instance_init) {
 272         ti->instance_init(obj);
 273     }
 274 }
 275
 276 void object_initialize_with_type(void *data, TypeImpl *type)
 277 {
 278     Object *obj = data;
 279
 280     g_assert(type != NULL);
 281     type_initialize(type);
 282
 283     g_assert(type->instance_size >= sizeof(Object));
 284     g_assert(type->abstract == false);
 285
 286     memset(obj, 0, type->instance_size);
 287     obj->class = type->class;
 288     QTAILQ_INIT(&obj->properties);
 289     object_init_with_type(obj, type);
 290 }
 291
 292 void object_initialize(void *data, const char *typename)
 293 {
 294     TypeImpl *type = type_get_by_name(typename);
 295
 296     object_initialize_with_type(data, type);
 297 }
 298
 299 static void object_property_del_all(Object *obj)
 300 {
 301     while (!QTAILQ_EMPTY(&obj->properties)) {
 302         ObjectProperty *prop = QTAILQ_FIRST(&obj->properties);
 303
 304         QTAILQ_REMOVE(&obj->properties, prop, node);
 305
 306         if (prop->release) {
 307             prop->release(obj, prop->name, prop->opaque);
 308         }
 309
 310         g_free(prop->name);
 311         g_free(prop->type);
 312         g_free(prop);
 313     }
 314 }
 315
 316 static void object_property_del_child(Object *obj, Object *child, Error **errp)
 317 {
 318     ObjectProperty *prop;
 319
 320     QTAILQ_FOREACH(prop, &obj->properties, node) {
 321         if (strstart(prop->type, "child<", NULL) && prop->opaque == child) {
 322             object_property_del(obj, prop->name, errp);
 323             break;
 324         }
 325     }
 326 }
 327
 328 void object_unparent(Object *obj)
 329 {
 330     if (obj->parent) {
 331         object_property_del_child(obj->parent, obj, NULL);
 332     }
 333 }
 334
 335 static void object_deinit(Object *obj, TypeImpl *type)
 336 {
 337     if (type->instance_finalize) {
 338         type->instance_finalize(obj);
 339     }
 340
 341     while (obj->interfaces) {
 342         Interface *iface_obj = obj->interfaces->data;
 343         obj->interfaces = g_slist_delete_link(obj->interfaces, obj->interfaces);
 344         object_delete(OBJECT(iface_obj));
 345     }
 346
 347     if (type_has_parent(type)) {
 348         object_deinit(obj, type_get_parent(type));
 349     }
 350
 351     object_unparent(obj);
 352 }
 353
 354 void object_finalize(void *data)
 355 {
 356     Object *obj = data;
 357     TypeImpl *ti = obj->class->type;
 358
 359     object_deinit(obj, ti);
 360     object_property_del_all(obj);
 361
 362     g_assert(obj->ref == 0);
 363 }
 364
 365 Object *object_new_with_type(Type type)
 366 {
 367     Object *obj;
 368
 369     g_assert(type != NULL);
 370     type_initialize(type);
 371
 372     obj = g_malloc(type->instance_size);
 373     object_initialize_with_type(obj, type);
 374     object_ref(obj);
 375
 376     return obj;
 377 }
 378
 379 Object *object_new(const char *typename)
 380 {
 381     TypeImpl *ti = type_get_by_name(typename);
 382
 383     return object_new_with_type(ti);
 384 }
 385
 386 void object_delete(Object *obj)
 387 {
 388     object_unref(obj);
 389     g_assert(obj->ref == 0);
 390     g_free(obj);
 391 }
 392
 393 static bool type_is_ancestor(TypeImpl *type, TypeImpl *target_type)
 394 {
 395     assert(target_type);
 396
 397     /* Check if typename is a direct ancestor of type */
 398     while (type) {
 399         if (type == target_type) {
 400             return true;
 401         }
 402
 403         type = type_get_parent(type);
 404     }
 405
 406     return false;
 407 }
 408
 409 static bool object_is_type(Object *obj, TypeImpl *target_type)
 410 {
 411     return !target_type || type_is_ancestor(obj->class->type, target_type);
 412 }
 413
 414 Object *object_dynamic_cast(Object *obj, const char *typename)
 415 {
 416     TypeImpl *target_type = type_get_by_name(typename);
 417     GSList *i;
 418
 419     /* Check if typename is a direct ancestor.  Special-case TYPE_OBJECT,
 420      * we want to go back from interfaces to the parent.
 421     */
 422     if (target_type && object_is_type(obj, target_type)) {
 423         return obj;
 424     }
 425
 426     /* Check if obj is an interface and its containing object is a direct
 427      * ancestor of typename.  In principle we could do this test at the very
 428      * beginning of object_dynamic_cast, avoiding a second call to
 429      * object_is_type.  However, casting between interfaces is relatively
 430      * rare, and object_is_type(obj, type_interface) would fail almost always.
 431      *
 432      * Perhaps we could add a magic value to the object header for increased
 433      * (run-time) type safety and to speed up tests like this one.  If we ever
 434      * do that we can revisit the order here.
 435      */
 436     if (object_is_type(obj, type_interface)) {
 437         assert(!obj->interfaces);
 438         obj = INTERFACE(obj)->obj;
 439         if (object_is_type(obj, target_type)) {
 440             return obj;
 441         }
 442     }
 443
 444     if (!target_type) {
 445         return obj;
 446     }
 447
 448     /* Check if obj has an interface of typename */
 449     for (i = obj->interfaces; i; i = i->next) {
 450         Interface *iface = i->data;
 451
 452         if (object_is_type(OBJECT(iface), target_type)) {
 453             return OBJECT(iface);
 454         }
 455     }
 456
 457     return NULL;
 458 }
 459
 460
 461 static void register_types(void)
 462 {
 463     static TypeInfo interface_info = {
 464         .name = TYPE_INTERFACE,
 465         .instance_size = sizeof(Interface),
 466         .abstract = true,
 467     };
 468
 469     type_interface = type_register_static(&interface_info);
 470 }
 471
 472 type_init(register_types)
 473
 474 Object *object_dynamic_cast_assert(Object *obj, const char *typename)
 475 {
 476     Object *inst;
 477
 478     inst = object_dynamic_cast(obj, typename);
 479
 480     if (!inst) {
 481         fprintf(stderr, "Object %p is not an instance of type %s\n",
 482                 obj, typename);
 483         abort();
 484     }
 485
 486     return inst;
 487 }
 488
 489 ObjectClass *object_class_dynamic_cast(ObjectClass *class,
 490                                        const char *typename)
 491 {
 492     TypeImpl *target_type = type_get_by_name(typename);
 493     TypeImpl *type = class->type;
 494
 495     while (type) {
 496         if (type == target_type) {
 497             return class;
 498         }
 499
 500         type = type_get_parent(type);
 501     }
 502
 503     return NULL;
 504 }
 505
 506 ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
 507                                               const char *typename)
 508 {
 509     ObjectClass *ret = object_class_dynamic_cast(class, typename);
 510
 511     if (!ret) {
 512         fprintf(stderr, "Object %p is not an instance of type %s\n",
 513                 class, typename);
 514         abort();
 515     }
 516
 517     return ret;
 518 }
 519
 520 const char *object_get_typename(Object *obj)
 521 {
 522     return obj->class->type->name;
 523 }
 524
 525 ObjectClass *object_get_class(Object *obj)
 526 {
 527     return obj->class;
 528 }
 529
 530 const char *object_class_get_name(ObjectClass *klass)
 531 {
 532     return klass->type->name;
 533 }
 534
 535 ObjectClass *object_class_by_name(const char *typename)
 536 {
 537     TypeImpl *type = type_get_by_name(typename);
 538
 539     if (!type) {
 540         return NULL;
 541     }
 542
 543     type_initialize(type);
 544
 545     return type->class;
 546 }
 547
 548 typedef struct OCFData
 549 {
 550     void (*fn)(ObjectClass *klass, void *opaque);
 551     const char *implements_type;
 552     bool include_abstract;
 553     void *opaque;
 554 } OCFData;
 555
 556 static void object_class_foreach_tramp(gpointer key, gpointer value,
 557                                        gpointer opaque)
 558 {
 559     OCFData *data = opaque;
 560     TypeImpl *type = value;
 561     ObjectClass *k;
 562
 563     type_initialize(type);
 564     k = type->class;
 565
 566     if (!data->include_abstract && type->abstract) {
 567         return;
 568     }
 569
 570     if (data->implements_type &&
 571         !object_class_dynamic_cast(k, data->implements_type)) {
 572         return;
 573     }
 574
 575     data->fn(k, data->opaque);
 576 }
 577
 578 void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
 579                           const char *implements_type, bool include_abstract,
 580                           void *opaque)
 581 {
 582     OCFData data = { fn, implements_type, include_abstract, opaque };
 583
 584     g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);
 585 }
 586
 587 static void object_class_get_list_tramp(ObjectClass *klass, void *opaque)
 588 {
 589     GSList **list = opaque;
 590
 591     *list = g_slist_prepend(*list, klass);
 592 }
 593
 594 GSList *object_class_get_list(const char *implements_type,
 595                               bool include_abstract)
 596 {
 597     GSList *list = NULL;
 598
 599     object_class_foreach(object_class_get_list_tramp,
 600                          implements_type, include_abstract, &list);
 601     return list;
 602 }
 603
 604 void object_ref(Object *obj)
 605 {
 606     obj->ref++;
 607 }
 608
 609 void object_unref(Object *obj)
 610 {
 611     g_assert(obj->ref > 0);
 612     obj->ref--;
 613
 614     /* parent always holds a reference to its children */
 615     if (obj->ref == 0) {
 616         object_finalize(obj);
 617     }
 618 }
 619
 620 void object_property_add(Object *obj, const char *name, const char *type,
 621                          ObjectPropertyAccessor *get,
 622                          ObjectPropertyAccessor *set,
 623                          ObjectPropertyRelease *release,
 624                          void *opaque, Error **errp)
 625 {
 626     ObjectProperty *prop = g_malloc0(sizeof(*prop));
 627
 628     prop->name = g_strdup(name);
 629     prop->type = g_strdup(type);
 630
 631     prop->get = get;
 632     prop->set = set;
 633     prop->release = release;
 634     prop->opaque = opaque;
 635
 636     QTAILQ_INSERT_TAIL(&obj->properties, prop, node);
 637 }
 638
 639 static ObjectProperty *object_property_find(Object *obj, const char *name)
 640 {
 641     ObjectProperty *prop;
 642
 643     QTAILQ_FOREACH(prop, &obj->properties, node) {
 644         if (strcmp(prop->name, name) == 0) {
 645             return prop;
 646         }
 647     }
 648
 649     return NULL;
 650 }
 651
 652 void object_property_del(Object *obj, const char *name, Error **errp)
 653 {
 654     ObjectProperty *prop = object_property_find(obj, name);
 655
 656     QTAILQ_REMOVE(&obj->properties, prop, node);
 657
 658     prop->release(obj, prop->name, prop->opaque);
 659
 660     g_free(prop->name);
 661     g_free(prop->type);
 662     g_free(prop);
 663 }
 664
 665 void object_property_get(Object *obj, Visitor *v, const char *name,
 666                          Error **errp)
 667 {
 668     ObjectProperty *prop = object_property_find(obj, name);
 669
 670     if (prop == NULL) {
 671         error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);
 672         return;
 673     }
 674
 675     if (!prop->get) {
 676         error_set(errp, QERR_PERMISSION_DENIED);
 677     } else {
 678         prop->get(obj, v, prop->opaque, name, errp);
 679     }
 680 }
 681
 682 void object_property_set(Object *obj, Visitor *v, const char *name,
 683                          Error **errp)
 684 {
 685     ObjectProperty *prop = object_property_find(obj, name);
 686
 687     if (prop == NULL) {
 688         error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);
 689         return;
 690     }
 691
 692     if (!prop->set) {
 693         error_set(errp, QERR_PERMISSION_DENIED);
 694     } else {
 695         prop->set(obj, v, prop->opaque, name, errp);
 696     }
 697 }
 698
 699 void object_property_set_str(Object *obj, const char *value,
 700                              const char *name, Error **errp)
 701 {
 702     QString *qstr = qstring_from_str(value);
 703     object_property_set_qobject(obj, QOBJECT(qstr), name, errp);
 704
 705     QDECREF(qstr);
 706 }
 707
 708 char *object_property_get_str(Object *obj, const char *name,
 709                               Error **errp)
 710 {
 711     QObject *ret = object_property_get_qobject(obj, name, errp);
 712     QString *qstring;
 713     char *retval;
 714
 715     if (!ret) {
 716         return NULL;
 717     }
 718     qstring = qobject_to_qstring(ret);
 719     if (!qstring) {
 720         error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "string");
 721         retval = NULL;
 722     } else {
 723         retval = g_strdup(qstring_get_str(qstring));
 724     }
 725
 726     QDECREF(qstring);
 727     return retval;
 728 }
 729
 730 void object_property_set_link(Object *obj, Object *value,
 731                               const char *name, Error **errp)
 732 {
 733     object_property_set_str(obj, object_get_canonical_path(value),
 734                             name, errp);
 735 }
 736
 737 Object *object_property_get_link(Object *obj, const char *name,
 738                                  Error **errp)
 739 {
 740     char *str = object_property_get_str(obj, name, errp);
 741     Object *target = NULL;
 742
 743     if (str && *str) {
 744         target = object_resolve_path(str, NULL);
 745         if (!target) {
 746             error_set(errp, QERR_DEVICE_NOT_FOUND, str);
 747         }
 748     }
 749
 750     g_free(str);
 751     return target;
 752 }
 753
 754 void object_property_set_bool(Object *obj, bool value,
 755                               const char *name, Error **errp)
 756 {
 757     QBool *qbool = qbool_from_int(value);
 758     object_property_set_qobject(obj, QOBJECT(qbool), name, errp);
 759
 760     QDECREF(qbool);
 761 }
 762
 763 bool object_property_get_bool(Object *obj, const char *name,
 764                               Error **errp)
 765 {
 766     QObject *ret = object_property_get_qobject(obj, name, errp);
 767     QBool *qbool;
 768     bool retval;
 769
 770     if (!ret) {
 771         return false;
 772     }
 773     qbool = qobject_to_qbool(ret);
 774     if (!qbool) {
 775         error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "boolean");
 776         retval = false;
 777     } else {
 778         retval = qbool_get_int(qbool);
 779     }
 780
 781     QDECREF(qbool);
 782     return retval;
 783 }
 784
 785 void object_property_set_int(Object *obj, int64_t value,
 786                              const char *name, Error **errp)
 787 {
 788     QInt *qint = qint_from_int(value);
 789     object_property_set_qobject(obj, QOBJECT(qint), name, errp);
 790
 791     QDECREF(qint);
 792 }
 793
 794 int64_t object_property_get_int(Object *obj, const char *name,
 795                                 Error **errp)
 796 {
 797     QObject *ret = object_property_get_qobject(obj, name, errp);
 798     QInt *qint;
 799     int64_t retval;
 800
 801     if (!ret) {
 802         return -1;
 803     }
 804     qint = qobject_to_qint(ret);
 805     if (!qint) {
 806         error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "int");
 807         retval = -1;
 808     } else {
 809         retval = qint_get_int(qint);
 810     }
 811
 812     QDECREF(qint);
 813     return retval;
 814 }
 815
 816 void object_property_parse(Object *obj, const char *string,
 817                            const char *name, Error **errp)
 818 {
 819     StringInputVisitor *mi;
 820     mi = string_input_visitor_new(string);
 821     object_property_set(obj, string_input_get_visitor(mi), name, errp);
 822
 823     string_input_visitor_cleanup(mi);
 824 }
 825
 826 char *object_property_print(Object *obj, const char *name,
 827                             Error **errp)
 828 {
 829     StringOutputVisitor *mo;
 830     char *string;
 831
 832     mo = string_output_visitor_new();
 833     object_property_get(obj, string_output_get_visitor(mo), name, NULL);
 834     string = string_output_get_string(mo);
 835     string_output_visitor_cleanup(mo);
 836     return string;
 837 }
 838
 839 const char *object_property_get_type(Object *obj, const char *name, Error **errp)
 840 {
 841     ObjectProperty *prop = object_property_find(obj, name);
 842
 843     if (prop == NULL) {
 844         error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);
 845         return NULL;
 846     }
 847
 848     return prop->type;
 849 }
 850
 851 Object *object_get_root(void)
 852 {
 853     static Object *root;
 854
 855     if (!root) {
 856         root = object_new("container");
 857     }
 858
 859     return root;
 860 }
 861
 862 static void object_get_child_property(Object *obj, Visitor *v, void *opaque,
 863                                       const char *name, Error **errp)
 864 {
 865     Object *child = opaque;
 866     gchar *path;
 867
 868     path = object_get_canonical_path(child);
 869     visit_type_str(v, &path, name, errp);
 870     g_free(path);
 871 }
 872
 873 static void object_finalize_child_property(Object *obj, const char *name,
 874                                            void *opaque)
 875 {
 876     Object *child = opaque;
 877
 878     object_unref(child);
 879 }
 880
 881 void object_property_add_child(Object *obj, const char *name,
 882                                Object *child, Error **errp)
 883 {
 884     gchar *type;
 885
 886     /* Registering an interface object in the composition tree will mightily
 887      * confuse object_get_canonical_path (which, on the other hand, knows how
 888      * to get the canonical path of an interface object).
 889      */
 890     assert(!object_is_type(obj, type_interface));
 891
 892     type = g_strdup_printf("child<%s>", object_get_typename(OBJECT(child)));
 893
 894     object_property_add(obj, name, type, object_get_child_property,
 895                         NULL, object_finalize_child_property, child, errp);
 896
 897     object_ref(child);
 898     g_assert(child->parent == NULL);
 899     child->parent = obj;
 900
 901     g_free(type);
 902 }
 903
 904 static void object_get_link_property(Object *obj, Visitor *v, void *opaque,
 905                                      const char *name, Error **errp)
 906 {
 907     Object **child = opaque;
 908     gchar *path;
 909
 910     if (*child) {
 911         path = object_get_canonical_path(*child);
 912         visit_type_str(v, &path, name, errp);
 913         g_free(path);
 914     } else {
 915         path = (gchar *)"";
 916         visit_type_str(v, &path, name, errp);
 917     }
 918 }
 919
 920 static void object_set_link_property(Object *obj, Visitor *v, void *opaque,
 921                                      const char *name, Error **errp)
 922 {
 923     Object **child = opaque;
 924     Object *old_target;
 925     bool ambiguous = false;
 926     const char *type;
 927     char *path;
 928     gchar *target_type;
 929
 930     type = object_property_get_type(obj, name, NULL);
 931
 932     visit_type_str(v, &path, name, errp);
 933
 934     old_target = *child;
 935     *child = NULL;
 936
 937     if (strcmp(path, "") != 0) {
 938         Object *target;
 939
 940         /* Go from link<FOO> to FOO.  */
 941         target_type = g_strndup(&type[5], strlen(type) - 6);
 942         target = object_resolve_path_type(path, target_type, &ambiguous);
 943
 944         if (ambiguous) {
 945             error_set(errp, QERR_AMBIGUOUS_PATH, path);
 946         } else if (target) {
 947             object_ref(target);
 948             *child = target;
 949         } else {
 950             target = object_resolve_path(path, &ambiguous);
 951             if (target || ambiguous) {
 952                 error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, target_type);
 953             } else {
 954                 error_set(errp, QERR_DEVICE_NOT_FOUND, path);
 955             }
 956         }
 957         g_free(target_type);
 958     }
 959
 960     g_free(path);
 961
 962     if (old_target != NULL) {
 963         object_unref(old_target);
 964     }
 965 }
 966
 967 void object_property_add_link(Object *obj, const char *name,
 968                               const char *type, Object **child,
 969                               Error **errp)
 970 {
 971     gchar *full_type;
 972
 973     full_type = g_strdup_printf("link<%s>", type);
 974
 975     object_property_add(obj, name, full_type,
 976                         object_get_link_property,
 977                         object_set_link_property,
 978                         NULL, child, errp);
 979
 980     g_free(full_type);
 981 }
 982
 983 gchar *object_get_canonical_path(Object *obj)
 984 {
 985     Object *root = object_get_root();
 986     char *newpath = NULL, *path = NULL;
 987
 988     if (object_is_type(obj, type_interface)) {
 989         obj = INTERFACE(obj)->obj;
 990     }
 991
 992     while (obj != root) {
 993         ObjectProperty *prop = NULL;
 994
 995         g_assert(obj->parent != NULL);
 996
 997         QTAILQ_FOREACH(prop, &obj->parent->properties, node) {
 998             if (!strstart(prop->type, "child<", NULL)) {
 999                 continue;
1000             }
1001
1002             if (prop->opaque == obj) {
1003                 if (path) {
1004                     newpath = g_strdup_printf("%s/%s", prop->name, path);
1005                     g_free(path);
1006                     path = newpath;
1007                 } else {
1008                     path = g_strdup(prop->name);
1009                 }
1010                 break;
1011             }
1012         }
1013
1014         g_assert(prop != NULL);
1015
1016         obj = obj->parent;
1017     }
1018
1019     newpath = g_strdup_printf("/%s", path);
1020     g_free(path);
1021
1022     return newpath;
1023 }
1024
1025 static Object *object_resolve_abs_path(Object *parent,
1026                                           gchar **parts,
1027                                           const char *typename,
1028                                           int index)
1029 {
1030     ObjectProperty *prop;
1031     Object *child;
1032
1033     if (parts[index] == NULL) {
1034         return object_dynamic_cast(parent, typename);
1035     }
1036
1037     if (strcmp(parts[index], "") == 0) {
1038         return object_resolve_abs_path(parent, parts, typename, index + 1);
1039     }
1040
1041     prop = object_property_find(parent, parts[index]);
1042     if (prop == NULL) {
1043         return NULL;
1044     }
1045
1046     child = NULL;
1047     if (strstart(prop->type, "link<", NULL)) {
1048         Object **pchild = prop->opaque;
1049         if (*pchild) {
1050             child = *pchild;
1051         }
1052     } else if (strstart(prop->type, "child<", NULL)) {
1053         child = prop->opaque;
1054     }
1055
1056     if (!child) {
1057         return NULL;
1058     }
1059
1060     return object_resolve_abs_path(child, parts, typename, index + 1);
1061 }
1062
1063 static Object *object_resolve_partial_path(Object *parent,
1064                                               gchar **parts,
1065                                               const char *typename,
1066                                               bool *ambiguous)
1067 {
1068     Object *obj;
1069     ObjectProperty *prop;
1070
1071     obj = object_resolve_abs_path(parent, parts, typename, 0);
1072
1073     QTAILQ_FOREACH(prop, &parent->properties, node) {
1074         Object *found;
1075
1076         if (!strstart(prop->type, "child<", NULL)) {
1077             continue;
1078         }
1079
1080         found = object_resolve_partial_path(prop->opaque, parts,
1081                                             typename, ambiguous);
1082         if (found) {
1083             if (obj) {
1084                 if (ambiguous) {
1085                     *ambiguous = true;
1086                 }
1087                 return NULL;
1088             }
1089             obj = found;
1090         }
1091
1092         if (ambiguous && *ambiguous) {
1093             return NULL;
1094         }
1095     }
1096
1097     return obj;
1098 }
1099
1100 Object *object_resolve_path_type(const char *path, const char *typename,
1101                                  bool *ambiguous)
1102 {
1103     bool partial_path = true;
1104     Object *obj;
1105     gchar **parts;
1106
1107     parts = g_strsplit(path, "/", 0);
1108     if (parts == NULL || parts[0] == NULL) {
1109         g_strfreev(parts);
1110         return object_get_root();
1111     }
1112
1113     if (strcmp(parts[0], "") == 0) {
1114         partial_path = false;
1115     }
1116
1117     if (partial_path) {
1118         if (ambiguous) {
1119             *ambiguous = false;
1120         }
1121         obj = object_resolve_partial_path(object_get_root(), parts,
1122                                           typename, ambiguous);
1123     } else {
1124         obj = object_resolve_abs_path(object_get_root(), parts, typename, 1);
1125     }
1126
1127     g_strfreev(parts);
1128
1129     return obj;
1130 }
1131
1132 Object *object_resolve_path(const char *path, bool *ambiguous)
1133 {
1134     return object_resolve_path_type(path, TYPE_OBJECT, ambiguous);
1135 }
1136
1137 typedef struct StringProperty
1138 {
1139     char *(*get)(Object *, Error **);
1140     void (*set)(Object *, const char *, Error **);
1141 } StringProperty;
1142
1143 static void property_get_str(Object *obj, Visitor *v, void *opaque,
1144                              const char *name, Error **errp)
1145 {
1146     StringProperty *prop = opaque;
1147     char *value;
1148
1149     value = prop->get(obj, errp);
1150     if (value) {
1151         visit_type_str(v, &value, name, errp);
1152         g_free(value);
1153     }
1154 }
1155
1156 static void property_set_str(Object *obj, Visitor *v, void *opaque,
1157                              const char *name, Error **errp)
1158 {
1159     StringProperty *prop = opaque;
1160     char *value;
1161     Error *local_err = NULL;
1162
1163     visit_type_str(v, &value, name, &local_err);
1164     if (local_err) {
1165         error_propagate(errp, local_err);
1166         return;
1167     }
1168
1169     prop->set(obj, value, errp);
1170     g_free(value);
1171 }
1172
1173 static void property_release_str(Object *obj, const char *name,
1174                                  void *opaque)
1175 {
1176     StringProperty *prop = opaque;
1177     g_free(prop);
1178 }
1179
1180 void object_property_add_str(Object *obj, const char *name,
1181                            char *(*get)(Object *, Error **),
1182                            void (*set)(Object *, const char *, Error **),
1183                            Error **errp)
1184 {
1185     StringProperty *prop = g_malloc0(sizeof(*prop));
1186
1187     prop->get = get;
1188     prop->set = set;
1189
1190     object_property_add(obj, name, "string",
1191                         get ? property_get_str : NULL,
1192                         set ? property_set_str : NULL,
1193                         property_release_str,
1194                         prop, errp);
1195 }