qobject/qdict.c

   1 /*
   2  * QDict Module
   3  *
   4  * Copyright (C) 2009 Red Hat Inc.
   5  *
   6  * Authors:
   7  *  Luiz Capitulino <lcapitulino@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "qapi/qmp/qint.h"
  15 #include "qapi/qmp/qfloat.h"
  16 #include "qapi/qmp/qdict.h"
  17 #include "qapi/qmp/qbool.h"
  18 #include "qapi/qmp/qstring.h"
  19 #include "qapi/qmp/qobject.h"
  20 #include "qemu/queue.h"
  21 #include "qemu-common.h"
  22 #include "qemu/cutils.h"
  23
  24 /**
  25  * qdict_new(): Create a new QDict
  26  *
  27  * Return strong reference.
  28  */
  29 QDict *qdict_new(void)
  30 {
  31     QDict *qdict;
  32
  33     qdict = g_malloc0(sizeof(*qdict));
  34     qobject_init(QOBJECT(qdict), QTYPE_QDICT);
  35
  36     return qdict;
  37 }
  38
  39 /**
  40  * qobject_to_qdict(): Convert a QObject into a QDict
  41  */
  42 QDict *qobject_to_qdict(const QObject *obj)
  43 {
  44     if (!obj || qobject_type(obj) != QTYPE_QDICT) {
  45         return NULL;
  46     }
  47     return container_of(obj, QDict, base);
  48 }
  49
  50 /**
  51  * tdb_hash(): based on the hash agorithm from gdbm, via tdb
  52  * (from module-init-tools)
  53  */
  54 static unsigned int tdb_hash(const char *name)
  55 {
  56     unsigned value;     /* Used to compute the hash value.  */
  57     unsigned   i;       /* Used to cycle through random values. */
  58
  59     /* Set the initial value from the key size. */
  60     for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
  61         value = (value + (((const unsigned char *)name)[i] << (i*5 % 24)));
  62
  63     return (1103515243 * value + 12345);
  64 }
  65
  66 /**
  67  * alloc_entry(): allocate a new QDictEntry
  68  */
  69 static QDictEntry *alloc_entry(const char *key, QObject *value)
  70 {
  71     QDictEntry *entry;
  72
  73     entry = g_malloc0(sizeof(*entry));
  74     entry->key = g_strdup(key);
  75     entry->value = value;
  76
  77     return entry;
  78 }
  79
  80 /**
  81  * qdict_entry_value(): Return qdict entry value
  82  *
  83  * Return weak reference.
  84  */
  85 QObject *qdict_entry_value(const QDictEntry *entry)
  86 {
  87     return entry->value;
  88 }
  89
  90 /**
  91  * qdict_entry_key(): Return qdict entry key
  92  *
  93  * Return a *pointer* to the string, it has to be duplicated before being
  94  * stored.
  95  */
  96 const char *qdict_entry_key(const QDictEntry *entry)
  97 {
  98     return entry->key;
  99 }
 100
 101 /**
 102  * qdict_find(): List lookup function
 103  */
 104 static QDictEntry *qdict_find(const QDict *qdict,
 105                               const char *key, unsigned int bucket)
 106 {
 107     QDictEntry *entry;
 108
 109     QLIST_FOREACH(entry, &qdict->table[bucket], next)
 110         if (!strcmp(entry->key, key))
 111             return entry;
 112
 113     return NULL;
 114 }
 115
 116 /**
 117  * qdict_put_obj(): Put a new QObject into the dictionary
 118  *
 119  * Insert the pair 'key:value' into 'qdict', if 'key' already exists
 120  * its 'value' will be replaced.
 121  *
 122  * This is done by freeing the reference to the stored QObject and
 123  * storing the new one in the same entry.
 124  *
 125  * NOTE: ownership of 'value' is transferred to the QDict
 126  */
 127 void qdict_put_obj(QDict *qdict, const char *key, QObject *value)
 128 {
 129     unsigned int bucket;
 130     QDictEntry *entry;
 131
 132     bucket = tdb_hash(key) % QDICT_BUCKET_MAX;
 133     entry = qdict_find(qdict, key, bucket);
 134     if (entry) {
 135         /* replace key's value */
 136         qobject_decref(entry->value);
 137         entry->value = value;
 138     } else {
 139         /* allocate a new entry */
 140         entry = alloc_entry(key, value);
 141         QLIST_INSERT_HEAD(&qdict->table[bucket], entry, next);
 142         qdict->size++;
 143     }
 144 }
 145
 146 /**
 147  * qdict_get(): Lookup for a given 'key'
 148  *
 149  * Return a weak reference to the QObject associated with 'key' if
 150  * 'key' is present in the dictionary, NULL otherwise.
 151  */
 152 QObject *qdict_get(const QDict *qdict, const char *key)
 153 {
 154     QDictEntry *entry;
 155
 156     entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_BUCKET_MAX);
 157     return (entry == NULL ? NULL : entry->value);
 158 }
 159
 160 /**
 161  * qdict_haskey(): Check if 'key' exists
 162  *
 163  * Return 1 if 'key' exists in the dict, 0 otherwise
 164  */
 165 int qdict_haskey(const QDict *qdict, const char *key)
 166 {
 167     unsigned int bucket = tdb_hash(key) % QDICT_BUCKET_MAX;
 168     return (qdict_find(qdict, key, bucket) == NULL ? 0 : 1);
 169 }
 170
 171 /**
 172  * qdict_size(): Return the size of the dictionary
 173  */
 174 size_t qdict_size(const QDict *qdict)
 175 {
 176     return qdict->size;
 177 }
 178
 179 /**
 180  * qdict_get_obj(): Get a QObject of a specific type
 181  */
 182 static QObject *qdict_get_obj(const QDict *qdict, const char *key, QType type)
 183 {
 184     QObject *obj;
 185
 186     obj = qdict_get(qdict, key);
 187     assert(obj != NULL);
 188     assert(qobject_type(obj) == type);
 189
 190     return obj;
 191 }
 192
 193 /**
 194  * qdict_get_double(): Get an number mapped by 'key'
 195  *
 196  * This function assumes that 'key' exists and it stores a
 197  * QFloat or QInt object.
 198  *
 199  * Return number mapped by 'key'.
 200  */
 201 double qdict_get_double(const QDict *qdict, const char *key)
 202 {
 203     QObject *obj = qdict_get(qdict, key);
 204
 205     assert(obj);
 206     switch (qobject_type(obj)) {
 207     case QTYPE_QFLOAT:
 208         return qfloat_get_double(qobject_to_qfloat(obj));
 209     case QTYPE_QINT:
 210         return qint_get_int(qobject_to_qint(obj));
 211     default:
 212         abort();
 213     }
 214 }
 215
 216 /**
 217  * qdict_get_int(): Get an integer mapped by 'key'
 218  *
 219  * This function assumes that 'key' exists and it stores a
 220  * QInt object.
 221  *
 222  * Return integer mapped by 'key'.
 223  */
 224 int64_t qdict_get_int(const QDict *qdict, const char *key)
 225 {
 226     return qint_get_int(qobject_to_qint(qdict_get(qdict, key)));
 227 }
 228
 229 /**
 230  * qdict_get_bool(): Get a bool mapped by 'key'
 231  *
 232  * This function assumes that 'key' exists and it stores a
 233  * QBool object.
 234  *
 235  * Return bool mapped by 'key'.
 236  */
 237 bool qdict_get_bool(const QDict *qdict, const char *key)
 238 {
 239     return qbool_get_bool(qobject_to_qbool(qdict_get(qdict, key)));
 240 }
 241
 242 /**
 243  * qdict_get_qlist(): Get the QList mapped by 'key'
 244  *
 245  * This function assumes that 'key' exists and it stores a
 246  * QList object.
 247  *
 248  * Return QList mapped by 'key'.
 249  */
 250 QList *qdict_get_qlist(const QDict *qdict, const char *key)
 251 {
 252     return qobject_to_qlist(qdict_get_obj(qdict, key, QTYPE_QLIST));
 253 }
 254
 255 /**
 256  * qdict_get_qdict(): Get the QDict mapped by 'key'
 257  *
 258  * This function assumes that 'key' exists and it stores a
 259  * QDict object.
 260  *
 261  * Return QDict mapped by 'key'.
 262  */
 263 QDict *qdict_get_qdict(const QDict *qdict, const char *key)
 264 {
 265     return qobject_to_qdict(qdict_get(qdict, key));
 266 }
 267
 268 /**
 269  * qdict_get_str(): Get a pointer to the stored string mapped
 270  * by 'key'
 271  *
 272  * This function assumes that 'key' exists and it stores a
 273  * QString object.
 274  *
 275  * Return pointer to the string mapped by 'key'.
 276  */
 277 const char *qdict_get_str(const QDict *qdict, const char *key)
 278 {
 279     return qstring_get_str(qobject_to_qstring(qdict_get(qdict, key)));
 280 }
 281
 282 /**
 283  * qdict_get_try_int(): Try to get integer mapped by 'key'
 284  *
 285  * Return integer mapped by 'key', if it is not present in
 286  * the dictionary or if the stored object is not of QInt type
 287  * 'def_value' will be returned.
 288  */
 289 int64_t qdict_get_try_int(const QDict *qdict, const char *key,
 290                           int64_t def_value)
 291 {
 292     QInt *qint = qobject_to_qint(qdict_get(qdict, key));
 293
 294     return qint ? qint_get_int(qint) : def_value;
 295 }
 296
 297 /**
 298  * qdict_get_try_bool(): Try to get a bool mapped by 'key'
 299  *
 300  * Return bool mapped by 'key', if it is not present in the
 301  * dictionary or if the stored object is not of QBool type
 302  * 'def_value' will be returned.
 303  */
 304 bool qdict_get_try_bool(const QDict *qdict, const char *key, bool def_value)
 305 {
 306     QBool *qbool = qobject_to_qbool(qdict_get(qdict, key));
 307
 308     return qbool ? qbool_get_bool(qbool) : def_value;
 309 }
 310
 311 /**
 312  * qdict_get_try_str(): Try to get a pointer to the stored string
 313  * mapped by 'key'
 314  *
 315  * Return a pointer to the string mapped by 'key', if it is not present
 316  * in the dictionary or if the stored object is not of QString type
 317  * NULL will be returned.
 318  */
 319 const char *qdict_get_try_str(const QDict *qdict, const char *key)
 320 {
 321     QString *qstr = qobject_to_qstring(qdict_get(qdict, key));
 322
 323     return qstr ? qstring_get_str(qstr) : NULL;
 324 }
 325
 326 /**
 327  * qdict_iter(): Iterate over all the dictionary's stored values.
 328  *
 329  * This function allows the user to provide an iterator, which will be
 330  * called for each stored value in the dictionary.
 331  */
 332 void qdict_iter(const QDict *qdict,
 333                 void (*iter)(const char *key, QObject *obj, void *opaque),
 334                 void *opaque)
 335 {
 336     int i;
 337     QDictEntry *entry;
 338
 339     for (i = 0; i < QDICT_BUCKET_MAX; i++) {
 340         QLIST_FOREACH(entry, &qdict->table[i], next)
 341             iter(entry->key, entry->value, opaque);
 342     }
 343 }
 344
 345 static QDictEntry *qdict_next_entry(const QDict *qdict, int first_bucket)
 346 {
 347     int i;
 348
 349     for (i = first_bucket; i < QDICT_BUCKET_MAX; i++) {
 350         if (!QLIST_EMPTY(&qdict->table[i])) {
 351             return QLIST_FIRST(&qdict->table[i]);
 352         }
 353     }
 354
 355     return NULL;
 356 }
 357
 358 /**
 359  * qdict_first(): Return first qdict entry for iteration.
 360  */
 361 const QDictEntry *qdict_first(const QDict *qdict)
 362 {
 363     return qdict_next_entry(qdict, 0);
 364 }
 365
 366 /**
 367  * qdict_next(): Return next qdict entry in an iteration.
 368  */
 369 const QDictEntry *qdict_next(const QDict *qdict, const QDictEntry *entry)
 370 {
 371     QDictEntry *ret;
 372
 373     ret = QLIST_NEXT(entry, next);
 374     if (!ret) {
 375         unsigned int bucket = tdb_hash(entry->key) % QDICT_BUCKET_MAX;
 376         ret = qdict_next_entry(qdict, bucket + 1);
 377     }
 378
 379     return ret;
 380 }
 381
 382 /**
 383  * qdict_clone_shallow(): Clones a given QDict. Its entries are not copied, but
 384  * another reference is added.
 385  */
 386 QDict *qdict_clone_shallow(const QDict *src)
 387 {
 388     QDict *dest;
 389     QDictEntry *entry;
 390     int i;
 391
 392     dest = qdict_new();
 393
 394     for (i = 0; i < QDICT_BUCKET_MAX; i++) {
 395         QLIST_FOREACH(entry, &src->table[i], next) {
 396             qobject_incref(entry->value);
 397             qdict_put_obj(dest, entry->key, entry->value);
 398         }
 399     }
 400
 401     return dest;
 402 }
 403
 404 /**
 405  * qentry_destroy(): Free all the memory allocated by a QDictEntry
 406  */
 407 static void qentry_destroy(QDictEntry *e)
 408 {
 409     assert(e != NULL);
 410     assert(e->key != NULL);
 411     assert(e->value != NULL);
 412
 413     qobject_decref(e->value);
 414     g_free(e->key);
 415     g_free(e);
 416 }
 417
 418 /**
 419  * qdict_del(): Delete a 'key:value' pair from the dictionary
 420  *
 421  * This will destroy all data allocated by this entry.
 422  */
 423 void qdict_del(QDict *qdict, const char *key)
 424 {
 425     QDictEntry *entry;
 426
 427     entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_BUCKET_MAX);
 428     if (entry) {
 429         QLIST_REMOVE(entry, next);
 430         qentry_destroy(entry);
 431         qdict->size--;
 432     }
 433 }
 434
 435 /**
 436  * qdict_destroy_obj(): Free all the memory allocated by a QDict
 437  */
 438 void qdict_destroy_obj(QObject *obj)
 439 {
 440     int i;
 441     QDict *qdict;
 442
 443     assert(obj != NULL);
 444     qdict = qobject_to_qdict(obj);
 445
 446     for (i = 0; i < QDICT_BUCKET_MAX; i++) {
 447         QDictEntry *entry = QLIST_FIRST(&qdict->table[i]);
 448         while (entry) {
 449             QDictEntry *tmp = QLIST_NEXT(entry, next);
 450             QLIST_REMOVE(entry, next);
 451             qentry_destroy(entry);
 452             entry = tmp;
 453         }
 454     }
 455
 456     g_free(qdict);
 457 }
 458
 459 /**
 460  * qdict_copy_default(): If no entry mapped by 'key' exists in 'dst' yet, the
 461  * value of 'key' in 'src' is copied there (and the refcount increased
 462  * accordingly).
 463  */
 464 void qdict_copy_default(QDict *dst, QDict *src, const char *key)
 465 {
 466     QObject *val;
 467
 468     if (qdict_haskey(dst, key)) {
 469         return;
 470     }
 471
 472     val = qdict_get(src, key);
 473     if (val) {
 474         qobject_incref(val);
 475         qdict_put_obj(dst, key, val);
 476     }
 477 }
 478
 479 /**
 480  * qdict_set_default_str(): If no entry mapped by 'key' exists in 'dst' yet, a
 481  * new QString initialised by 'val' is put there.
 482  */
 483 void qdict_set_default_str(QDict *dst, const char *key, const char *val)
 484 {
 485     if (qdict_haskey(dst, key)) {
 486         return;
 487     }
 488
 489     qdict_put(dst, key, qstring_from_str(val));
 490 }
 491
 492 static void qdict_flatten_qdict(QDict *qdict, QDict *target,
 493                                 const char *prefix);
 494
 495 static void qdict_flatten_qlist(QList *qlist, QDict *target, const char *prefix)
 496 {
 497     QObject *value;
 498     const QListEntry *entry;
 499     char *new_key;
 500     int i;
 501
 502     /* This function is never called with prefix == NULL, i.e., it is always
 503      * called from within qdict_flatten_q(list|dict)(). Therefore, it does not
 504      * need to remove list entries during the iteration (the whole list will be
 505      * deleted eventually anyway from qdict_flatten_qdict()). */
 506     assert(prefix);
 507
 508     entry = qlist_first(qlist);
 509
 510     for (i = 0; entry; entry = qlist_next(entry), i++) {
 511         value = qlist_entry_obj(entry);
 512         new_key = g_strdup_printf("%s.%i", prefix, i);
 513
 514         if (qobject_type(value) == QTYPE_QDICT) {
 515             qdict_flatten_qdict(qobject_to_qdict(value), target, new_key);
 516         } else if (qobject_type(value) == QTYPE_QLIST) {
 517             qdict_flatten_qlist(qobject_to_qlist(value), target, new_key);
 518         } else {
 519             /* All other types are moved to the target unchanged. */
 520             qobject_incref(value);
 521             qdict_put_obj(target, new_key, value);
 522         }
 523
 524         g_free(new_key);
 525     }
 526 }
 527
 528 static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
 529 {
 530     QObject *value;
 531     const QDictEntry *entry, *next;
 532     char *new_key;
 533     bool delete;
 534
 535     entry = qdict_first(qdict);
 536
 537     while (entry != NULL) {
 538
 539         next = qdict_next(qdict, entry);
 540         value = qdict_entry_value(entry);
 541         new_key = NULL;
 542         delete = false;
 543
 544         if (prefix) {
 545             new_key = g_strdup_printf("%s.%s", prefix, entry->key);
 546         }
 547
 548         if (qobject_type(value) == QTYPE_QDICT) {
 549             /* Entries of QDicts are processed recursively, the QDict object
 550              * itself disappears. */
 551             qdict_flatten_qdict(qobject_to_qdict(value), target,
 552                                 new_key ? new_key : entry->key);
 553             delete = true;
 554         } else if (qobject_type(value) == QTYPE_QLIST) {
 555             qdict_flatten_qlist(qobject_to_qlist(value), target,
 556                                 new_key ? new_key : entry->key);
 557             delete = true;
 558         } else if (prefix) {
 559             /* All other objects are moved to the target unchanged. */
 560             qobject_incref(value);
 561             qdict_put_obj(target, new_key, value);
 562             delete = true;
 563         }
 564
 565         g_free(new_key);
 566
 567         if (delete) {
 568             qdict_del(qdict, entry->key);
 569
 570             /* Restart loop after modifying the iterated QDict */
 571             entry = qdict_first(qdict);
 572             continue;
 573         }
 574
 575         entry = next;
 576     }
 577 }
 578
 579 /**
 580  * qdict_flatten(): For each nested QDict with key x, all fields with key y
 581  * are moved to this QDict and their key is renamed to "x.y". For each nested
 582  * QList with key x, the field at index y is moved to this QDict with the key
 583  * "x.y" (i.e., the reverse of what qdict_array_split() does).
 584  * This operation is applied recursively for nested QDicts and QLists.
 585  */
 586 void qdict_flatten(QDict *qdict)
 587 {
 588     qdict_flatten_qdict(qdict, qdict, NULL);
 589 }
 590
 591 /* extract all the src QDict entries starting by start into dst */
 592 void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start)
 593
 594 {
 595     const QDictEntry *entry, *next;
 596     const char *p;
 597
 598     *dst = qdict_new();
 599     entry = qdict_first(src);
 600
 601     while (entry != NULL) {
 602         next = qdict_next(src, entry);
 603         if (strstart(entry->key, start, &p)) {
 604             qobject_incref(entry->value);
 605             qdict_put_obj(*dst, p, entry->value);
 606             qdict_del(src, entry->key);
 607         }
 608         entry = next;
 609     }
 610 }
 611
 612 static int qdict_count_prefixed_entries(const QDict *src, const char *start)
 613 {
 614     const QDictEntry *entry;
 615     int count = 0;
 616
 617     for (entry = qdict_first(src); entry; entry = qdict_next(src, entry)) {
 618         if (strstart(entry->key, start, NULL)) {
 619             if (count == INT_MAX) {
 620                 return -ERANGE;
 621             }
 622             count++;
 623         }
 624     }
 625
 626     return count;
 627 }
 628
 629 /**
 630  * qdict_array_split(): This function moves array-like elements of a QDict into
 631  * a new QList. Every entry in the original QDict with a key "%u" or one
 632  * prefixed "%u.", where %u designates an unsigned integer starting at 0 and
 633  * incrementally counting up, will be moved to a new QDict at index %u in the
 634  * output QList with the key prefix removed, if that prefix is "%u.". If the
 635  * whole key is just "%u", the whole QObject will be moved unchanged without
 636  * creating a new QDict. The function terminates when there is no entry in the
 637  * QDict with a prefix directly (incrementally) following the last one; it also
 638  * returns if there are both entries with "%u" and "%u." for the same index %u.
 639  * Example: {"0.a": 42, "0.b": 23, "1.x": 0, "4.y": 1, "o.o": 7, "2": 66}
 640  *      (or {"1.x": 0, "4.y": 1, "0.a": 42, "o.o": 7, "0.b": 23, "2": 66})
 641  *       => [{"a": 42, "b": 23}, {"x": 0}, 66]
 642  *      and {"4.y": 1, "o.o": 7} (remainder of the old QDict)
 643  */
 644 void qdict_array_split(QDict *src, QList **dst)
 645 {
 646     unsigned i;
 647
 648     *dst = qlist_new();
 649
 650     for (i = 0; i < UINT_MAX; i++) {
 651         QObject *subqobj;
 652         bool is_subqdict;
 653         QDict *subqdict;
 654         char indexstr[32], prefix[32];
 655         size_t snprintf_ret;
 656
 657         snprintf_ret = snprintf(indexstr, 32, "%u", i);
 658         assert(snprintf_ret < 32);
 659
 660         subqobj = qdict_get(src, indexstr);
 661
 662         snprintf_ret = snprintf(prefix, 32, "%u.", i);
 663         assert(snprintf_ret < 32);
 664
 665         /* Overflow is the same as positive non-zero results */
 666         is_subqdict = qdict_count_prefixed_entries(src, prefix);
 667
 668         // There may be either a single subordinate object (named "%u") or
 669         // multiple objects (each with a key prefixed "%u."), but not both.
 670         if (!subqobj == !is_subqdict) {
 671             break;
 672         }
 673
 674         if (is_subqdict) {
 675             qdict_extract_subqdict(src, &subqdict, prefix);
 676             assert(qdict_size(subqdict) > 0);
 677         } else {
 678             qobject_incref(subqobj);
 679             qdict_del(src, indexstr);
 680         }
 681
 682         qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict));
 683     }
 684 }
 685
 686 /**
 687  * qdict_array_entries(): Returns the number of direct array entries if the
 688  * sub-QDict of src specified by the prefix in subqdict (or src itself for
 689  * prefix == "") is valid as an array, i.e. the length of the created list if
 690  * the sub-QDict would become empty after calling qdict_array_split() on it. If
 691  * the array is not valid, -EINVAL is returned.
 692  */
 693 int qdict_array_entries(QDict *src, const char *subqdict)
 694 {
 695     const QDictEntry *entry;
 696     unsigned i;
 697     unsigned entries = 0;
 698     size_t subqdict_len = strlen(subqdict);
 699
 700     assert(!subqdict_len || subqdict[subqdict_len - 1] == '.');
 701
 702     /* qdict_array_split() loops until UINT_MAX, but as we want to return
 703      * negative errors, we only have a signed return value here. Any additional
 704      * entries will lead to -EINVAL. */
 705     for (i = 0; i < INT_MAX; i++) {
 706         QObject *subqobj;
 707         int subqdict_entries;
 708         size_t slen = 32 + subqdict_len;
 709         char indexstr[slen], prefix[slen];
 710         size_t snprintf_ret;
 711
 712         snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
 713         assert(snprintf_ret < slen);
 714
 715         subqobj = qdict_get(src, indexstr);
 716
 717         snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
 718         assert(snprintf_ret < slen);
 719
 720         subqdict_entries = qdict_count_prefixed_entries(src, prefix);
 721         if (subqdict_entries < 0) {
 722             return subqdict_entries;
 723         }
 724
 725         /* There may be either a single subordinate object (named "%u") or
 726          * multiple objects (each with a key prefixed "%u."), but not both. */
 727         if (subqobj && subqdict_entries) {
 728             return -EINVAL;
 729         } else if (!subqobj && !subqdict_entries) {
 730             break;
 731         }
 732
 733         entries += subqdict_entries ? subqdict_entries : 1;
 734     }
 735
 736     /* Consider everything handled that isn't part of the given sub-QDict */
 737     for (entry = qdict_first(src); entry; entry = qdict_next(src, entry)) {
 738         if (!strstart(qdict_entry_key(entry), subqdict, NULL)) {
 739             entries++;
 740         }
 741     }
 742
 743     /* Anything left in the sub-QDict that wasn't handled? */
 744     if (qdict_size(src) != entries) {
 745         return -EINVAL;
 746     }
 747
 748     return i;
 749 }
 750
 751 /**
 752  * qdict_join(): Absorb the src QDict into the dest QDict, that is, move all
 753  * elements from src to dest.
 754  *
 755  * If an element from src has a key already present in dest, it will not be
 756  * moved unless overwrite is true.
 757  *
 758  * If overwrite is true, the conflicting values in dest will be discarded and
 759  * replaced by the corresponding values from src.
 760  *
 761  * Therefore, with overwrite being true, the src QDict will always be empty when
 762  * this function returns. If overwrite is false, the src QDict will be empty
 763  * iff there were no conflicts.
 764  */
 765 void qdict_join(QDict *dest, QDict *src, bool overwrite)
 766 {
 767     const QDictEntry *entry, *next;
 768
 769     entry = qdict_first(src);
 770     while (entry) {
 771         next = qdict_next(src, entry);
 772
 773         if (overwrite || !qdict_haskey(dest, entry->key)) {
 774             qobject_incref(entry->value);
 775             qdict_put_obj(dest, entry->key, entry->value);
 776             qdict_del(src, entry->key);
 777         }
 778
 779         entry = next;
 780     }
 781 }