qapi/qobject-input-visitor.c

   1 /*
   2  * Input Visitor
   3  *
   4  * Copyright (C) 2012-2017 Red Hat, Inc.
   5  * Copyright IBM, Corp. 2011
   6  *
   7  * Authors:
   8  *  Anthony Liguori   <aliguori@us.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  11  * See the COPYING.LIB file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include <math.h>
  17 #include "qapi/error.h"
  18 #include "qapi/qobject-input-visitor.h"
  19 #include "qapi/visitor-impl.h"
  20 #include "qemu/queue.h"
  21 #include "qemu-common.h"
  22 #include "qapi/qmp/qjson.h"
  23 #include "qapi/qmp/types.h"
  24 #include "qapi/qmp/qerror.h"
  25 #include "qemu/cutils.h"
  26 #include "qemu/option.h"
  27
  28 typedef struct StackObject {
  29     const char *name;            /* Name of @obj in its parent, if any */
  30     QObject *obj;                /* QDict or QList being visited */
  31     void *qapi; /* sanity check that caller uses same pointer */
  32
  33     GHashTable *h;              /* If @obj is QDict: unvisited keys */
  34     const QListEntry *entry;    /* If @obj is QList: unvisited tail */
  35     unsigned index;             /* If @obj is QList: list index of @entry */
  36
  37     QSLIST_ENTRY(StackObject) node; /* parent */
  38 } StackObject;
  39
  40 struct QObjectInputVisitor {
  41     Visitor visitor;
  42
  43     /* Root of visit at visitor creation. */
  44     QObject *root;
  45     bool keyval;                /* Assume @root made with keyval_parse() */
  46
  47     /* Stack of objects being visited (all entries will be either
  48      * QDict or QList). */
  49     QSLIST_HEAD(, StackObject) stack;
  50
  51     GString *errname;           /* Accumulator for full_name() */
  52 };
  53
  54 static QObjectInputVisitor *to_qiv(Visitor *v)
  55 {
  56     return container_of(v, QObjectInputVisitor, visitor);
  57 }
  58
  59 /*
  60  * Find the full name of something @qiv is currently visiting.
  61  * @qiv is visiting something named @name in the stack of containers
  62  * @qiv->stack.
  63  * If @n is zero, return its full name.
  64  * If @n is positive, return the full name of the @n-th container
  65  * counting from the top.  The stack of containers must have at least
  66  * @n elements.
  67  * The returned string is valid until the next full_name_nth(@v) or
  68  * destruction of @v.
  69  */
  70 static const char *full_name_nth(QObjectInputVisitor *qiv, const char *name,
  71                                  int n)
  72 {
  73     StackObject *so;
  74     char buf[32];
  75
  76     if (qiv->errname) {
  77         g_string_truncate(qiv->errname, 0);
  78     } else {
  79         qiv->errname = g_string_new("");
  80     }
  81
  82     QSLIST_FOREACH(so , &qiv->stack, node) {
  83         if (n) {
  84             n--;
  85         } else if (qobject_type(so->obj) == QTYPE_QDICT) {
  86             g_string_prepend(qiv->errname, name ?: "<anonymous>");
  87             g_string_prepend_c(qiv->errname, '.');
  88         } else {
  89             snprintf(buf, sizeof(buf),
  90                      qiv->keyval ? ".%u" : "[%u]",
  91                      so->index);
  92             g_string_prepend(qiv->errname, buf);
  93         }
  94         name = so->name;
  95     }
  96     assert(!n);
  97
  98     if (name) {
  99         g_string_prepend(qiv->errname, name);
 100     } else if (qiv->errname->str[0] == '.') {
 101         g_string_erase(qiv->errname, 0, 1);
 102     } else if (!qiv->errname->str[0]) {
 103         return "<anonymous>";
 104     }
 105
 106     return qiv->errname->str;
 107 }
 108
 109 static const char *full_name(QObjectInputVisitor *qiv, const char *name)
 110 {
 111     return full_name_nth(qiv, name, 0);
 112 }
 113
 114 static QObject *qobject_input_try_get_object(QObjectInputVisitor *qiv,
 115                                              const char *name,
 116                                              bool consume)
 117 {
 118     StackObject *tos;
 119     QObject *qobj;
 120     QObject *ret;
 121
 122     if (QSLIST_EMPTY(&qiv->stack)) {
 123         /* Starting at root, name is ignored. */
 124         assert(qiv->root);
 125         return qiv->root;
 126     }
 127
 128     /* We are in a container; find the next element. */
 129     tos = QSLIST_FIRST(&qiv->stack);
 130     qobj = tos->obj;
 131     assert(qobj);
 132
 133     if (qobject_type(qobj) == QTYPE_QDICT) {
 134         assert(name);
 135         ret = qdict_get(qobject_to_qdict(qobj), name);
 136         if (tos->h && consume && ret) {
 137             bool removed = g_hash_table_remove(tos->h, name);
 138             assert(removed);
 139         }
 140     } else {
 141         assert(qobject_type(qobj) == QTYPE_QLIST);
 142         assert(!name);
 143         if (tos->entry) {
 144             ret = qlist_entry_obj(tos->entry);
 145             if (consume) {
 146                 tos->entry = qlist_next(tos->entry);
 147             }
 148         } else {
 149             ret = NULL;
 150         }
 151         if (consume) {
 152             tos->index++;
 153         }
 154     }
 155
 156     return ret;
 157 }
 158
 159 static QObject *qobject_input_get_object(QObjectInputVisitor *qiv,
 160                                          const char *name,
 161                                          bool consume, Error **errp)
 162 {
 163     QObject *obj = qobject_input_try_get_object(qiv, name, consume);
 164
 165     if (!obj) {
 166         error_setg(errp, QERR_MISSING_PARAMETER, full_name(qiv, name));
 167     }
 168     return obj;
 169 }
 170
 171 static const char *qobject_input_get_keyval(QObjectInputVisitor *qiv,
 172                                             const char *name,
 173                                             Error **errp)
 174 {
 175     QObject *qobj;
 176     QString *qstr;
 177
 178     qobj = qobject_input_get_object(qiv, name, true, errp);
 179     if (!qobj) {
 180         return NULL;
 181     }
 182
 183     qstr = qobject_to_qstring(qobj);
 184     if (!qstr) {
 185         switch (qobject_type(qobj)) {
 186         case QTYPE_QDICT:
 187         case QTYPE_QLIST:
 188             error_setg(errp, "Parameters '%s.*' are unexpected",
 189                        full_name(qiv, name));
 190             return NULL;
 191         default:
 192             /* Non-string scalar (should this be an assertion?) */
 193             error_setg(errp, "Internal error: parameter %s invalid",
 194                        full_name(qiv, name));
 195             return NULL;
 196         }
 197     }
 198
 199     return qstring_get_str(qstr);
 200 }
 201
 202 static void qdict_add_key(const char *key, QObject *obj, void *opaque)
 203 {
 204     GHashTable *h = opaque;
 205     g_hash_table_insert(h, (gpointer) key, NULL);
 206 }
 207
 208 static const QListEntry *qobject_input_push(QObjectInputVisitor *qiv,
 209                                             const char *name,
 210                                             QObject *obj, void *qapi)
 211 {
 212     GHashTable *h;
 213     StackObject *tos = g_new0(StackObject, 1);
 214
 215     assert(obj);
 216     tos->name = name;
 217     tos->obj = obj;
 218     tos->qapi = qapi;
 219
 220     if (qobject_type(obj) == QTYPE_QDICT) {
 221         h = g_hash_table_new(g_str_hash, g_str_equal);
 222         qdict_iter(qobject_to_qdict(obj), qdict_add_key, h);
 223         tos->h = h;
 224     } else {
 225         assert(qobject_type(obj) == QTYPE_QLIST);
 226         tos->entry = qlist_first(qobject_to_qlist(obj));
 227         tos->index = -1;
 228     }
 229
 230     QSLIST_INSERT_HEAD(&qiv->stack, tos, node);
 231     return tos->entry;
 232 }
 233
 234
 235 static void qobject_input_check_struct(Visitor *v, Error **errp)
 236 {
 237     QObjectInputVisitor *qiv = to_qiv(v);
 238     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 239     GHashTableIter iter;
 240     const char *key;
 241
 242     assert(tos && !tos->entry);
 243
 244     g_hash_table_iter_init(&iter, tos->h);
 245     if (g_hash_table_iter_next(&iter, (void **)&key, NULL)) {
 246         error_setg(errp, "Parameter '%s' is unexpected",
 247                    full_name(qiv, key));
 248     }
 249 }
 250
 251 static void qobject_input_stack_object_free(StackObject *tos)
 252 {
 253     if (tos->h) {
 254         g_hash_table_unref(tos->h);
 255     }
 256
 257     g_free(tos);
 258 }
 259
 260 static void qobject_input_pop(Visitor *v, void **obj)
 261 {
 262     QObjectInputVisitor *qiv = to_qiv(v);
 263     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 264
 265     assert(tos && tos->qapi == obj);
 266     QSLIST_REMOVE_HEAD(&qiv->stack, node);
 267     qobject_input_stack_object_free(tos);
 268 }
 269
 270 static void qobject_input_start_struct(Visitor *v, const char *name, void **obj,
 271                                        size_t size, Error **errp)
 272 {
 273     QObjectInputVisitor *qiv = to_qiv(v);
 274     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 275
 276     if (obj) {
 277         *obj = NULL;
 278     }
 279     if (!qobj) {
 280         return;
 281     }
 282     if (qobject_type(qobj) != QTYPE_QDICT) {
 283         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 284                    full_name(qiv, name), "object");
 285         return;
 286     }
 287
 288     qobject_input_push(qiv, name, qobj, obj);
 289
 290     if (obj) {
 291         *obj = g_malloc0(size);
 292     }
 293 }
 294
 295 static void qobject_input_end_struct(Visitor *v, void **obj)
 296 {
 297     QObjectInputVisitor *qiv = to_qiv(v);
 298     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 299
 300     assert(qobject_type(tos->obj) == QTYPE_QDICT && tos->h);
 301     qobject_input_pop(v, obj);
 302 }
 303
 304
 305 static void qobject_input_start_list(Visitor *v, const char *name,
 306                                      GenericList **list, size_t size,
 307                                      Error **errp)
 308 {
 309     QObjectInputVisitor *qiv = to_qiv(v);
 310     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 311     const QListEntry *entry;
 312
 313     if (list) {
 314         *list = NULL;
 315     }
 316     if (!qobj) {
 317         return;
 318     }
 319     if (qobject_type(qobj) != QTYPE_QLIST) {
 320         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 321                    full_name(qiv, name), "array");
 322         return;
 323     }
 324
 325     entry = qobject_input_push(qiv, name, qobj, list);
 326     if (entry && list) {
 327         *list = g_malloc0(size);
 328     }
 329 }
 330
 331 static GenericList *qobject_input_next_list(Visitor *v, GenericList *tail,
 332                                             size_t size)
 333 {
 334     QObjectInputVisitor *qiv = to_qiv(v);
 335     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 336
 337     assert(tos && tos->obj && qobject_type(tos->obj) == QTYPE_QLIST);
 338
 339     if (!tos->entry) {
 340         return NULL;
 341     }
 342     tail->next = g_malloc0(size);
 343     return tail->next;
 344 }
 345
 346 static void qobject_input_check_list(Visitor *v, Error **errp)
 347 {
 348     QObjectInputVisitor *qiv = to_qiv(v);
 349     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 350
 351     assert(tos && tos->obj && qobject_type(tos->obj) == QTYPE_QLIST);
 352
 353     if (tos->entry) {
 354         error_setg(errp, "Only %u list elements expected in %s",
 355                    tos->index + 1, full_name_nth(qiv, NULL, 1));
 356     }
 357 }
 358
 359 static void qobject_input_end_list(Visitor *v, void **obj)
 360 {
 361     QObjectInputVisitor *qiv = to_qiv(v);
 362     StackObject *tos = QSLIST_FIRST(&qiv->stack);
 363
 364     assert(qobject_type(tos->obj) == QTYPE_QLIST && !tos->h);
 365     qobject_input_pop(v, obj);
 366 }
 367
 368 static void qobject_input_start_alternate(Visitor *v, const char *name,
 369                                           GenericAlternate **obj, size_t size,
 370                                           Error **errp)
 371 {
 372     QObjectInputVisitor *qiv = to_qiv(v);
 373     QObject *qobj = qobject_input_get_object(qiv, name, false, errp);
 374
 375     if (!qobj) {
 376         *obj = NULL;
 377         return;
 378     }
 379     *obj = g_malloc0(size);
 380     (*obj)->type = qobject_type(qobj);
 381 }
 382
 383 static void qobject_input_type_int64(Visitor *v, const char *name, int64_t *obj,
 384                                      Error **errp)
 385 {
 386     QObjectInputVisitor *qiv = to_qiv(v);
 387     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 388     QNum *qnum;
 389
 390     if (!qobj) {
 391         return;
 392     }
 393     qnum = qobject_to_qnum(qobj);
 394     if (!qnum || !qnum_get_try_int(qnum, obj)) {
 395         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 396                    full_name(qiv, name), "integer");
 397     }
 398 }
 399
 400 static void qobject_input_type_int64_keyval(Visitor *v, const char *name,
 401                                             int64_t *obj, Error **errp)
 402 {
 403     QObjectInputVisitor *qiv = to_qiv(v);
 404     const char *str = qobject_input_get_keyval(qiv, name, errp);
 405
 406     if (!str) {
 407         return;
 408     }
 409
 410     if (qemu_strtoi64(str, NULL, 0, obj) < 0) {
 411         /* TODO report -ERANGE more nicely */
 412         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
 413                    full_name(qiv, name), "integer");
 414     }
 415 }
 416
 417 static void qobject_input_type_uint64(Visitor *v, const char *name,
 418                                       uint64_t *obj, Error **errp)
 419 {
 420     QObjectInputVisitor *qiv = to_qiv(v);
 421     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 422     QNum *qnum;
 423     int64_t val;
 424
 425     if (!qobj) {
 426         return;
 427     }
 428     qnum = qobject_to_qnum(qobj);
 429     if (!qnum) {
 430         goto err;
 431     }
 432
 433     if (qnum_get_try_uint(qnum, obj)) {
 434         return;
 435     }
 436
 437     /* Need to accept negative values for backward compatibility */
 438     if (qnum_get_try_int(qnum, &val)) {
 439         *obj = val;
 440         return;
 441     }
 442
 443 err:
 444     error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
 445                full_name(qiv, name), "uint64");
 446 }
 447
 448 static void qobject_input_type_uint64_keyval(Visitor *v, const char *name,
 449                                              uint64_t *obj, Error **errp)
 450 {
 451     QObjectInputVisitor *qiv = to_qiv(v);
 452     const char *str = qobject_input_get_keyval(qiv, name, errp);
 453
 454     if (!str) {
 455         return;
 456     }
 457
 458     if (qemu_strtou64(str, NULL, 0, obj) < 0) {
 459         /* TODO report -ERANGE more nicely */
 460         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
 461                    full_name(qiv, name), "integer");
 462     }
 463 }
 464
 465 static void qobject_input_type_bool(Visitor *v, const char *name, bool *obj,
 466                                     Error **errp)
 467 {
 468     QObjectInputVisitor *qiv = to_qiv(v);
 469     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 470     QBool *qbool;
 471
 472     if (!qobj) {
 473         return;
 474     }
 475     qbool = qobject_to_qbool(qobj);
 476     if (!qbool) {
 477         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 478                    full_name(qiv, name), "boolean");
 479         return;
 480     }
 481
 482     *obj = qbool_get_bool(qbool);
 483 }
 484
 485 static void qobject_input_type_bool_keyval(Visitor *v, const char *name,
 486                                            bool *obj, Error **errp)
 487 {
 488     QObjectInputVisitor *qiv = to_qiv(v);
 489     const char *str = qobject_input_get_keyval(qiv, name, errp);
 490
 491     if (!str) {
 492         return;
 493     }
 494
 495     if (!strcmp(str, "on")) {
 496         *obj = true;
 497     } else if (!strcmp(str, "off")) {
 498         *obj = false;
 499     } else {
 500         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
 501                    full_name(qiv, name), "'on' or 'off'");
 502     }
 503 }
 504
 505 static void qobject_input_type_str(Visitor *v, const char *name, char **obj,
 506                                    Error **errp)
 507 {
 508     QObjectInputVisitor *qiv = to_qiv(v);
 509     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 510     QString *qstr;
 511
 512     *obj = NULL;
 513     if (!qobj) {
 514         return;
 515     }
 516     qstr = qobject_to_qstring(qobj);
 517     if (!qstr) {
 518         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 519                    full_name(qiv, name), "string");
 520         return;
 521     }
 522
 523     *obj = g_strdup(qstring_get_str(qstr));
 524 }
 525
 526 static void qobject_input_type_str_keyval(Visitor *v, const char *name,
 527                                           char **obj, Error **errp)
 528 {
 529     QObjectInputVisitor *qiv = to_qiv(v);
 530     const char *str = qobject_input_get_keyval(qiv, name, errp);
 531
 532     *obj = g_strdup(str);
 533 }
 534
 535 static void qobject_input_type_number(Visitor *v, const char *name, double *obj,
 536                                       Error **errp)
 537 {
 538     QObjectInputVisitor *qiv = to_qiv(v);
 539     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 540     QNum *qnum;
 541
 542     if (!qobj) {
 543         return;
 544     }
 545     qnum = qobject_to_qnum(qobj);
 546     if (!qnum) {
 547         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 548                    full_name(qiv, name), "number");
 549         return;
 550     }
 551
 552     *obj = qnum_get_double(qnum);
 553 }
 554
 555 static void qobject_input_type_number_keyval(Visitor *v, const char *name,
 556                                              double *obj, Error **errp)
 557 {
 558     QObjectInputVisitor *qiv = to_qiv(v);
 559     const char *str = qobject_input_get_keyval(qiv, name, errp);
 560     char *endp;
 561
 562     if (!str) {
 563         return;
 564     }
 565
 566     errno = 0;
 567     *obj = strtod(str, &endp);
 568     if (errno || endp == str || *endp || !isfinite(*obj)) {
 569         /* TODO report -ERANGE more nicely */
 570         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 571                    full_name(qiv, name), "number");
 572     }
 573 }
 574
 575 static void qobject_input_type_any(Visitor *v, const char *name, QObject **obj,
 576                                    Error **errp)
 577 {
 578     QObjectInputVisitor *qiv = to_qiv(v);
 579     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 580
 581     *obj = NULL;
 582     if (!qobj) {
 583         return;
 584     }
 585
 586     qobject_incref(qobj);
 587     *obj = qobj;
 588 }
 589
 590 static void qobject_input_type_null(Visitor *v, const char *name, Error **errp)
 591 {
 592     QObjectInputVisitor *qiv = to_qiv(v);
 593     QObject *qobj = qobject_input_get_object(qiv, name, true, errp);
 594
 595     if (!qobj) {
 596         return;
 597     }
 598
 599     if (qobject_type(qobj) != QTYPE_QNULL) {
 600         error_setg(errp, QERR_INVALID_PARAMETER_TYPE,
 601                    full_name(qiv, name), "null");
 602     }
 603 }
 604
 605 static void qobject_input_type_size_keyval(Visitor *v, const char *name,
 606                                            uint64_t *obj, Error **errp)
 607 {
 608     QObjectInputVisitor *qiv = to_qiv(v);
 609     const char *str = qobject_input_get_keyval(qiv, name, errp);
 610
 611     if (!str) {
 612         return;
 613     }
 614
 615     if (qemu_strtosz(str, NULL, obj) < 0) {
 616         /* TODO report -ERANGE more nicely */
 617         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
 618                    full_name(qiv, name), "size");
 619     }
 620 }
 621
 622 static void qobject_input_optional(Visitor *v, const char *name, bool *present)
 623 {
 624     QObjectInputVisitor *qiv = to_qiv(v);
 625     QObject *qobj = qobject_input_try_get_object(qiv, name, false);
 626
 627     if (!qobj) {
 628         *present = false;
 629         return;
 630     }
 631
 632     *present = true;
 633 }
 634
 635 static void qobject_input_free(Visitor *v)
 636 {
 637     QObjectInputVisitor *qiv = to_qiv(v);
 638
 639     while (!QSLIST_EMPTY(&qiv->stack)) {
 640         StackObject *tos = QSLIST_FIRST(&qiv->stack);
 641
 642         QSLIST_REMOVE_HEAD(&qiv->stack, node);
 643         qobject_input_stack_object_free(tos);
 644     }
 645
 646     qobject_decref(qiv->root);
 647     if (qiv->errname) {
 648         g_string_free(qiv->errname, TRUE);
 649     }
 650     g_free(qiv);
 651 }
 652
 653 static QObjectInputVisitor *qobject_input_visitor_base_new(QObject *obj)
 654 {
 655     QObjectInputVisitor *v = g_malloc0(sizeof(*v));
 656
 657     assert(obj);
 658
 659     v->visitor.type = VISITOR_INPUT;
 660     v->visitor.start_struct = qobject_input_start_struct;
 661     v->visitor.check_struct = qobject_input_check_struct;
 662     v->visitor.end_struct = qobject_input_end_struct;
 663     v->visitor.start_list = qobject_input_start_list;
 664     v->visitor.next_list = qobject_input_next_list;
 665     v->visitor.check_list = qobject_input_check_list;
 666     v->visitor.end_list = qobject_input_end_list;
 667     v->visitor.start_alternate = qobject_input_start_alternate;
 668     v->visitor.optional = qobject_input_optional;
 669     v->visitor.free = qobject_input_free;
 670
 671     v->root = obj;
 672     qobject_incref(obj);
 673
 674     return v;
 675 }
 676
 677 Visitor *qobject_input_visitor_new(QObject *obj)
 678 {
 679     QObjectInputVisitor *v = qobject_input_visitor_base_new(obj);
 680
 681     v->visitor.type_int64 = qobject_input_type_int64;
 682     v->visitor.type_uint64 = qobject_input_type_uint64;
 683     v->visitor.type_bool = qobject_input_type_bool;
 684     v->visitor.type_str = qobject_input_type_str;
 685     v->visitor.type_number = qobject_input_type_number;
 686     v->visitor.type_any = qobject_input_type_any;
 687     v->visitor.type_null = qobject_input_type_null;
 688
 689     return &v->visitor;
 690 }
 691
 692 Visitor *qobject_input_visitor_new_keyval(QObject *obj)
 693 {
 694     QObjectInputVisitor *v = qobject_input_visitor_base_new(obj);
 695
 696     v->visitor.type_int64 = qobject_input_type_int64_keyval;
 697     v->visitor.type_uint64 = qobject_input_type_uint64_keyval;
 698     v->visitor.type_bool = qobject_input_type_bool_keyval;
 699     v->visitor.type_str = qobject_input_type_str_keyval;
 700     v->visitor.type_number = qobject_input_type_number_keyval;
 701     v->visitor.type_any = qobject_input_type_any;
 702     v->visitor.type_null = qobject_input_type_null;
 703     v->visitor.type_size = qobject_input_type_size_keyval;
 704     v->keyval = true;
 705
 706     return &v->visitor;
 707 }
 708
 709 Visitor *qobject_input_visitor_new_str(const char *str,
 710                                        const char *implied_key,
 711                                        Error **errp)
 712 {
 713     bool is_json = str[0] == '{';
 714     QObject *obj;
 715     QDict *args;
 716     Visitor *v;
 717
 718     if (is_json) {
 719         obj = qobject_from_json(str, errp);
 720         if (!obj) {
 721             /* Work around qobject_from_json() lossage TODO fix that */
 722             if (errp && !*errp) {
 723                 error_setg(errp, "JSON parse error");
 724                 return NULL;
 725             }
 726             return NULL;
 727         }
 728         args = qobject_to_qdict(obj);
 729         assert(args);
 730         v = qobject_input_visitor_new(QOBJECT(args));
 731     } else {
 732         args = keyval_parse(str, implied_key, errp);
 733         if (!args) {
 734             return NULL;
 735         }
 736         v = qobject_input_visitor_new_keyval(QOBJECT(args));
 737     }
 738     QDECREF(args);
 739
 740     return v;
 741 }