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authorEric Blake <eblake@redhat.com>2016-01-29 06:48:46 -0700
committerMarkus Armbruster <armbru@redhat.com>2016-02-08 17:29:55 +0100
commita16e3e5c5825c90887a863513916f93eeec16c55 (patch)
tree175ae43f51fac5213ccb7d130f9c9f83e42a46b3 /scripts/qapi.py
parent9dbb8fa7eff6e5e4cfd83ea26dc67f8404b84aa2 (diff)
qapi: Improve generated event use of qapi visitor
All other successful clients of visit_start_struct() were paired with an unconditional visit_end_struct(); but the generated code for events was relying on qmp_output_visitor_cleanup() to work on an incomplete visit. Alter the code to guarantee that the struct is completed, which will make a future patch to split visit_end_struct() easier to reason about. While at it, drop some assertions and comments that are not present in other uses of the qmp output visitor, and pass NULL rather than "" as the 'kind' parameter (matching most other uses where obj is NULL). The changes to the generated code look like: | qmp = qmp_event_build_dict("DEVICE_TRAY_MOVED"); | | qov = qmp_output_visitor_new(); |- g_assert(qov); |- | v = qmp_output_get_visitor(qov); |- g_assert(v); | |- /* Fake visit, as if all members are under a structure */ |- visit_start_struct(v, NULL, "", "DEVICE_TRAY_MOVED", 0, &err); |+ visit_start_struct(v, NULL, NULL, "DEVICE_TRAY_MOVED", 0, &err); | if (err) { | goto out; | } | visit_type_str(v, (char **)&device, "device", &err); | if (err) { |- goto out; |+ goto out_obj; | } | visit_type_bool(v, &tray_open, "tray-open", &err); | if (err) { |- goto out; |+ goto out_obj; | } |- visit_end_struct(v, &err); |+out_obj: |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } | | obj = qmp_output_get_qobject(qov); |- g_assert(obj != NULL); |+ g_assert(obj); | | qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_DEVICE_TRAY_MOVED, qmp, &err); Note that the 'goto out_obj' with no intervening code before the label, as well as the construct of 'err ? NULL : &err', are both a bit unusual but also temporary; they get fixed in a later patch that splits visit_end_struct() to drop its errp parameter by moving some checking before the label. But until that time, this was the simplest way to avoid the appearance of passing a possibly-set error to visit_end_struct(), even though actual code inspection shows that visit_end_struct() for a QMP output visitor will never set an error. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1454075341-13658-11-git-send-email-eblake@redhat.com> [Commit message's code diff tweaked] Signed-off-by: Markus Armbruster <armbru@redhat.com>
Diffstat (limited to 'scripts/qapi.py')
-rw-r--r--scripts/qapi.py5
1 files changed, 3 insertions, 2 deletions
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 0f032c3e67..9254e48fe3 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1636,7 +1636,8 @@ def gen_err_check(label='out', skiperr=False):
label=label)
-def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
+def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
+ label='out'):
ret = ''
if skiperr:
errparg = 'NULL'
@@ -1664,7 +1665,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
c_type=memb.type.c_name(), prefix=prefix, cast=cast,
c_name=c_name(memb.name), name=memb.name,
errp=errparg)
- ret += gen_err_check(skiperr=skiperr)
+ ret += gen_err_check(skiperr=skiperr, label=label)
if memb.optional:
pop_indent()