[Qemu-devel] [RFC PATCH 13/19] block-qdict: Clean up qdict_crumple() a bit

[Markus Armbruster <armbru@redhat.com>]

When you mix scalar and non-scalar keys, whether you get an "already
set as scalar" or an "already set as dict" error depends on qdict
iteration order.  Neither message makes much sense.  Replace by
""Cannot mix scalar and non-scalar keys".  This is similar to the
message we get for mixing list and non-list keys.

I find qdict_crumple()'s first loop hard to understand.  Rearrange it
and add a comment.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qobject/block-qdict.c | 42 +++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index a4e1c8d08f..35e9052816 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -403,7 +403,7 @@ static int qdict_is_list(QDict *maybe_list, Error **errp)
 QObject *qdict_crumple(const QDict *src, Error **errp)
 {
     const QDictEntry *ent;
-    QDict *two_level, *multi_level = NULL;
+    QDict *two_level, *multi_level = NULL, *child_dict;
     QObject *dst = NULL, *child;
     size_t i;
     char *prefix = NULL;
@@ -422,29 +422,29 @@ QObject *qdict_crumple(const QDict *src, Error **errp)
         }
 
         qdict_split_flat_key(ent->key, &prefix, &suffix);
-
         child = qdict_get(two_level, prefix);
+        child_dict = qobject_to(QDict, child);
+
+        if (child) {
+            /*
+             * An existing child must be a dict and @ent must be a
+             * dict member (i.e. suffix not null), or else @ent
+             * clashes.
+             */
+            if (!child_dict || !suffix) {
+                error_setg(errp,
+                           "Cannot mix scalar and non-scalar keys");
+                goto error;
+            }
+        } else if (suffix) {
+            child_dict = qdict_new();
+            qdict_put(two_level, prefix, child_dict);
+        } else {
+            qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
+        }
+
         if (suffix) {
-            QDict *child_dict = qobject_to(QDict, child);
-            if (!child_dict) {
-                if (child) {
-                    error_setg(errp, "Key %s prefix is already set as a scalar",
-                               prefix);
-                    goto error;
-                }
-
-                child_dict = qdict_new();
-                qdict_put_obj(two_level, prefix, QOBJECT(child_dict));
-            }
-
             qdict_put_obj(child_dict, suffix, qobject_ref(ent->value));
-        } else {
-            if (child) {
-                error_setg(errp, "Key %s prefix is already set as a dict",
-                           prefix);
-                goto error;
-            }
-            qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
         }
 
         g_free(prefix);
-- 
2.17.1