From 264748ad06e842eecd03f0085ed349c286621d7b Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Mon, 19 Feb 2018 22:19:29 -0500
Subject: [PATCH] qapi: Track all failures between visit_start/stop

Inside the generated code between visit_start_struct() and
visit_end_struct(), we were blindly setting the error into
the caller's errp parameter. But a future patch to split
visit_end_struct() will require that we take action based
on whether an error has occurred, which requires us to track
all actions through a local err. Rewrite the visits to be
more in line with the other generated calls.

Generated code changes look like:

| visit_start_struct(v, (void **)obj, "Abort", name, sizeof(Abort), &err);
|- if (!err) {
|- if (*obj) {
|- visit_type_Abort_fields(v, obj, errp);
|- }
|- visit_end_struct(v, &err);
|+ if (err) {
|+ goto out;
| }
|+ if (!*obj) {
|+ goto out_obj;
|+ }
|+ visit_type_Abort_fields(v, obj, &err);
|+ error_propagate(errp, err);
|+ err = NULL;
|+out_obj:
|+ visit_end_struct(v, &err);
|+out:
| error_propagate(errp, err);
| }

Backports commit 92b09babc11b60458c28cfe37eaa314de50e6241 from qemu
---
 qemu/scripts/qapi-visit.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/qemu/scripts/qapi-visit.py b/qemu/scripts/qapi-visit.py
index 2a36ee1d..e2976fd0 100644
--- a/qemu/scripts/qapi-visit.py
+++ b/qemu/scripts/qapi-visit.py
@@ -2,7 +2,7 @@
 # QAPI visitor generator
 #
 # Copyright IBM, Corp. 2011
-# Copyright (C) 2014-2015 Red Hat, Inc.
+# Copyright (C) 2014-2016 Red Hat, Inc.
 #
 # Authors:
 #  Anthony Liguori <aliguori@us.ibm.com>
@@ -121,12 +121,18 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
 
     visit_start_struct(v, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
 
-    if (!err) {
-        if (*obj) {
-            visit_type_%(c_name)s_fields(v, obj, errp);
-        }
-        visit_end_struct(v, &err);
+    if (err) {
+        goto out;
     }
+    if (!*obj) {
+        goto out_obj;
+    }
+    visit_type_%(c_name)s_fields(v, obj, &err);
+    error_propagate(errp, err);
+    err = NULL;
+out_obj:
+    visit_end_struct(v, &err);
+out:
     error_propagate(errp, err);
 }
 ''',