qdict: fix unbounded stack warning for qdict_array_entries

Here we use one g_strdup_printf() to replace the two stack allocated
array, considering it's more convenient, safe, and as long as it's
called rarely only when quorum device opens. This will remove the
unbound stack warning when compiling with "-Wstack-usage=1000000".
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

qobject/qdict.c

@@ -705,19 +705,16 @@ int qdict_array_entries(QDict *src, const char *subqdict)
     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;
+        char *prefix = g_strdup_printf("%s%u.", subqdict, i);
 
-        snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
-        assert(snprintf_ret < slen);
+        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
 
-        subqobj = qdict_get(src, indexstr);
+        /* Remove ending "." */
+        prefix[strlen(prefix) - 1] = 0;
+        subqobj = qdict_get(src, prefix);
 
-        snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
-        assert(snprintf_ret < slen);
+        g_free(prefix);
 
-        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
         if (subqdict_entries < 0) {
             return subqdict_entries;
         }