[Qemu-devel] [PATCH v6 10/23] vl: Improve use of qapi visitor

[Eric Blake <eblake@redhat.com>]

Cache the visitor in a local variable instead of repeatedly
calling the accessor.  Pass NULL for the visit_start_struct()
object (which matches the fact that we were already passing 0
for the size argument, because we aren't using the visit to
allocate a qapi struct).  Pass "object" for the struct name,
for better error messages. Reflow the logic so that we don't
have to undo an object_add().

A later patch will then split the error detection currently
in visit_struct_end(), at which point we can again hoist the
object_add() to occur before the label as one of the cleanups
enabled by that split.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v6: new patch, split from RFC on v5 7/46
---
 vl.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/vl.c b/vl.c
index 4d6263d..4e69815 100644
--- a/vl.c
+++ b/vl.c
@@ -2828,43 +2828,42 @@ static bool object_create_delayed(const char *type)
 static int object_create(void *opaque, QemuOpts *opts, Error **errp)
 {
     Error *err = NULL;
+    Error *err_end = NULL;
     char *type = NULL;
     char *id = NULL;
-    void *dummy = NULL;
     OptsVisitor *ov;
     QDict *pdict;
     bool (*type_predicate)(const char *) = opaque;
+    Visitor *v;

     ov = opts_visitor_new(opts);
     pdict = qemu_opts_to_qdict(opts, NULL);
+    v = opts_get_visitor(ov);

-    visit_start_struct(opts_get_visitor(ov), &dummy, NULL, NULL, 0, &err);
+    visit_start_struct(v, NULL, "object", NULL, 0, &err);
     if (err) {
         goto out;
     }

     qdict_del(pdict, "qom-type");
-    visit_type_str(opts_get_visitor(ov), &type, "qom-type", &err);
+    visit_type_str(v, &type, "qom-type", &err);
     if (err) {
         goto out;
     }
     if (!type_predicate(type)) {
-        goto out;
+        goto out_end;
     }

     qdict_del(pdict, "id");
-    visit_type_str(opts_get_visitor(ov), &id, "id", &err);
+    visit_type_str(v, &id, "id", &err);
     if (err) {
-        goto out;
+        goto out_end;
     }

-    object_add(type, id, pdict, opts_get_visitor(ov), &err);
-    if (err) {
-        goto out;
-    }
-    visit_end_struct(opts_get_visitor(ov), &err);
-    if (err) {
-        qmp_object_del(id, NULL);
+out_end:
+    visit_end_struct(v, &err_end);
+    if (!err && !err_end) {
+        object_add(type, id, pdict, v, &err);
     }

 out:
@@ -2873,7 +2872,6 @@ out:
     QDECREF(pdict);
     g_free(id);
     g_free(type);
-    g_free(dummy);
     if (err) {
         error_report_err(err);
         return -1;
-- 
2.4.3