+/**
+ * qdict_array_entries(): Returns the number of direct array entries if the
+ * sub-QDict of src specified by the prefix in subqdict (or src itself for
+ * prefix == "") is valid as an array, i.e. the length of the created list if
+ * the sub-QDict would become empty after calling qdict_array_split() on it. If
+ * the array is not valid, -EINVAL is returned.
+ */
+int qdict_array_entries(QDict *src, const char *subqdict)
+{
+ const QDictEntry *entry;
+ unsigned i;
+ unsigned entries = 0;
+ size_t subqdict_len = strlen(subqdict);
+
+ assert(!subqdict_len || subqdict[subqdict_len - 1] == '.');
+
+ /* qdict_array_split() loops until UINT_MAX, but as we want to return
+ * negative errors, we only have a signed return value here. Any additional
+ * entries will lead to -EINVAL. */
+ for (i = 0; i < INT_MAX; i++) {
+ QObject *subqobj;
+ int subqdict_entries;
+ size_t slen = 32 + subqdict_len;
+ char indexstr[slen], prefix[slen];
+ size_t snprintf_ret;
+
+ snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
+ assert(snprintf_ret < slen);
+
+ subqobj = qdict_get(src, indexstr);
+
+ snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
+ assert(snprintf_ret < slen);
+
+ subqdict_entries = qdict_count_prefixed_entries(src, prefix);
+ if (subqdict_entries < 0) {
+ return subqdict_entries;
+ }
+
+ /* There may be either a single subordinate object (named "%u") or
+ * multiple objects (each with a key prefixed "%u."), but not both. */
+ if (subqobj && subqdict_entries) {
+ return -EINVAL;
+ } else if (!subqobj && !subqdict_entries) {
+ break;
+ }
+
+ entries += subqdict_entries ? subqdict_entries : 1;
+ }
+
+ /* Consider everything handled that isn't part of the given sub-QDict */
+ for (entry = qdict_first(src); entry; entry = qdict_next(src, entry)) {
+ if (!strstart(qdict_entry_key(entry), subqdict, NULL)) {
+ entries++;
+ }
+ }
+
+ /* Anything left in the sub-QDict that wasn't handled? */
+ if (qdict_size(src) != entries) {
+ return -EINVAL;
+ }
+
+ return i;
+}
+