2 files changed, 63 insertions, 11 deletions

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index 80c653013f..42054cc274 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -158,20 +158,25 @@ void qdict_flatten(QDict *qdict)
     qdict_flatten_qdict(qdict, qdict, NULL);
 }
 
-/* extract all the src QDict entries starting by start into dst */
+/* extract all the src QDict entries starting by start into dst.
+ * If dst is NULL then the entries are simply removed from src. */
 void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start)
 
 {
     const QDictEntry *entry, *next;
     const char *p;
 
-    *dst = qdict_new();
+    if (dst) {
+        *dst = qdict_new();
+    }
     entry = qdict_first(src);
 
     while (entry != NULL) {
         next = qdict_next(src, entry);
         if (strstart(entry->key, start, &p)) {
-            qdict_put_obj(*dst, p, qobject_ref(entry->value));
+            if (dst) {
+                qdict_put_obj(*dst, p, qobject_ref(entry->value));
+            }
             qdict_del(src, entry->key);
         }
         entry = next;
diff --git a/qobject/qjson.c b/qobject/qjson.c
index 2f6a590e44..ab4040f235 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -39,7 +39,18 @@ static void parse_json(JSONMessageParser *parser, GQueue *tokens)
     s->result = json_parser_parse_err(tokens, s->ap, &s->err);
 }
 
-QObject *qobject_from_jsonv(const char *string, va_list *ap, Error **errp)
+/*
+ * Parse @string as JSON value.
+ * If @ap is non-null, interpolate %-escapes.
+ * Takes ownership of %p arguments.
+ * On success, return the JSON value.
+ * On failure, store an error through @errp and return NULL.
+ * Ownership of %p arguments becomes indeterminate then.  To avoid
+ * leaks, callers passing %p must terminate on error, e.g. by passing
+ * &error_abort.
+ */
+static QObject *qobject_from_jsonv(const char *string, va_list *ap,
+                                   Error **errp)
 {
     JSONParsingState state = {};
 
@@ -59,13 +70,37 @@ QObject *qobject_from_json(const char *string, Error **errp)
     return qobject_from_jsonv(string, NULL, errp);
 }
 
-QObject *qobject_from_jsonf(const char *string, ...)
+/*
+ * Parse @string as JSON value with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QObject.  It is never null.
+ */
+QObject *qobject_from_vjsonf_nofail(const char *string, va_list ap)
+{
+    va_list ap_copy;
+    QObject *obj;
+
+    /* va_copy() is needed when va_list is an array type */
+    va_copy(ap_copy, ap);
+    obj = qobject_from_jsonv(string, &ap_copy, &error_abort);
+    va_end(ap_copy);
+
+    assert(obj);
+    return obj;
+}
+
+/*
+ * Parse @string as JSON value with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QObject.  It is never null.
+ */
+QObject *qobject_from_jsonf_nofail(const char *string, ...)
 {
     QObject *obj;
     va_list ap;
 
     va_start(ap, string);
-    obj = qobject_from_jsonv(string, &ap, &error_abort);
+    obj = qobject_from_vjsonf_nofail(string, ap);
     va_end(ap);
 
     return obj;
@@ -76,17 +111,29 @@ QObject *qobject_from_jsonf(const char *string, ...)
  * Abort on error.  Do not use with untrusted @string.
  * Return the resulting QDict.  It is never null.
  */
+QDict *qdict_from_vjsonf_nofail(const char *string, va_list ap)
+{
+    QDict *qdict;
+
+    qdict = qobject_to(QDict, qobject_from_vjsonf_nofail(string, ap));
+    assert(qdict);
+    return qdict;
+}
+
+/*
+ * Parse @string as JSON object with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QDict.  It is never null.
+ */
 QDict *qdict_from_jsonf_nofail(const char *string, ...)
 {
-    QDict *obj;
+    QDict *qdict;
     va_list ap;
 
     va_start(ap, string);
-    obj = qobject_to(QDict, qobject_from_jsonv(string, &ap, &error_abort));
+    qdict = qdict_from_vjsonf_nofail(string, ap);
     va_end(ap);
-
-    assert(obj);
-    return obj;
+    return qdict;
 }
 
 typedef struct ToJsonIterState