qom/object.c

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