[Qemu-devel] [PATCH v6 09/23] hmp: 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
---
 hmp.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/hmp.c b/hmp.c
index c2b2c16..ec1d682 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1667,9 +1667,9 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)
     QemuOpts *opts;
     char *type = NULL;
     char *id = NULL;
-    void *dummy = NULL;
     OptsVisitor *ov;
     QDict *pdict;
+    Visitor *v;

     opts = qemu_opts_from_qdict(qemu_find_opts("object"), qdict, &err);
     if (err) {
@@ -1678,30 +1678,29 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)

     ov = opts_visitor_new(opts);
     pdict = qdict_clone_shallow(qdict);
+    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_clean;
     }

     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_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_end;
     }

-    object_add(type, id, pdict, opts_get_visitor(ov), &err);
-
 out_end:
-    visit_end_struct(opts_get_visitor(ov), &err_end);
-    if (!err && err_end) {
-        qmp_object_del(id, NULL);
+    visit_end_struct(v, &err_end);
+    if (!err && !err_end) {
+        object_add(type, id, pdict, v, &err);
     }
     error_propagate(&err, err_end);
 out_clean:
@@ -1711,7 +1710,6 @@ out_clean:
     qemu_opts_del(opts);
     g_free(id);
     g_free(type);
-    g_free(dummy);

 out:
     hmp_handle_error(mon, &err);
-- 
2.4.3