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qapi: Smooth visitor error checking in generated code
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Use visitor functions' return values to check for failure.  Eliminate
error_propagate() that are now unnecessary.  Delete @err that are now
unused.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-41-armbru@redhat.com>
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Markus Armbruster committed Jul 10, 2020
1 parent b11a093 commit cdd2b22
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Showing 3 changed files with 55 additions and 84 deletions.
60 changes: 23 additions & 37 deletions docs/devel/qapi-code-gen.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1420,8 +1420,6 @@ Example:

bool visit_type_UserDefOne_members(Visitor *v, UserDefOne *obj, Error **errp)
{
Error *err = NULL;

if (!visit_type_int(v, "integer", &obj->integer, errp)) {
return false;
}
Expand All @@ -1430,13 +1428,12 @@ Example:
return false;
}
}
error_propagate(errp, err);
return !err;
return true;
}

bool visit_type_UserDefOne(Visitor *v, const char *name, UserDefOne **obj, Error **errp)
{
Error *err = NULL;
bool ok = false;

if (!visit_start_struct(v, name, (void **)obj, sizeof(UserDefOne), errp)) {
return false;
Expand All @@ -1446,24 +1443,22 @@ Example:
assert(visit_is_dealloc(v));
goto out_obj;
}
visit_type_UserDefOne_members(v, *obj, &err);
if (err) {
if (!visit_type_UserDefOne_members(v, *obj, errp)) {
goto out_obj;
}
visit_check_struct(v, &err);
ok = visit_check_struct(v, errp);
out_obj:
visit_end_struct(v, (void **)obj);
if (err && visit_is_input(v)) {
if (!ok && visit_is_input(v)) {
qapi_free_UserDefOne(*obj);
*obj = NULL;
}
error_propagate(errp, err);
return !err;
return ok;
}

bool visit_type_UserDefOneList(Visitor *v, const char *name, UserDefOneList **obj, Error **errp)
{
Error *err = NULL;
bool ok = false;
UserDefOneList *tail;
size_t size = sizeof(**obj);

Expand All @@ -1473,33 +1468,27 @@ Example:

for (tail = *obj; tail;
tail = (UserDefOneList *)visit_next_list(v, (GenericList *)tail, size)) {
visit_type_UserDefOne(v, NULL, &tail->value, &err);
if (err) {
break;
if (!visit_type_UserDefOne(v, NULL, &tail->value, errp)) {
goto out_obj;
}
}

if (!err) {
visit_check_list(v, &err);
}
ok = visit_check_list(v, errp);
out_obj:
visit_end_list(v, (void **)obj);
if (err && visit_is_input(v)) {
if (!ok && visit_is_input(v)) {
qapi_free_UserDefOneList(*obj);
*obj = NULL;
}
error_propagate(errp, err);
return !err;
return ok;
}

bool visit_type_q_obj_my_command_arg_members(Visitor *v, q_obj_my_command_arg *obj, Error **errp)
{
Error *err = NULL;

if (!visit_type_UserDefOneList(v, "arg1", &obj->arg1, errp)) {
return false;
}
error_propagate(errp, err);
return !err;
return true;
}

[Uninteresting stuff omitted...]
Expand Down Expand Up @@ -1554,15 +1543,12 @@ Example:

static void qmp_marshal_output_UserDefOne(UserDefOne *ret_in, QObject **ret_out, Error **errp)
{
Error *err = NULL;
Visitor *v;

v = qobject_output_visitor_new(ret_out);
visit_type_UserDefOne(v, "unused", &ret_in, &err);
if (!err) {
if (visit_type_UserDefOne(v, "unused", &ret_in, errp)) {
visit_complete(v, ret_out);
}
error_propagate(errp, err);
visit_free(v);
v = qapi_dealloc_visitor_new();
visit_type_UserDefOne(v, "unused", &ret_in, NULL);
Expand All @@ -1572,40 +1558,40 @@ Example:
void qmp_marshal_my_command(QDict *args, QObject **ret, Error **errp)
{
Error *err = NULL;
bool ok = false;
Visitor *v;
UserDefOne *retval;
q_obj_my_command_arg arg = {0};

v = qobject_input_visitor_new(QOBJECT(args));
visit_start_struct(v, NULL, NULL, 0, &err);
if (err) {
if (!visit_start_struct(v, NULL, NULL, 0, errp)) {
goto out;
}
visit_type_q_obj_my_command_arg_members(v, &arg, &err);
if (!err) {
visit_check_struct(v, &err);
if (visit_type_q_obj_my_command_arg_members(v, &arg, errp)) {
ok = visit_check_struct(v, errp);
}
visit_end_struct(v, NULL);
if (err) {
if (!ok) {
goto out;
}

retval = qmp_my_command(arg.arg1, &err);
error_propagate(errp, err);
if (err) {
goto out;
}

qmp_marshal_output_UserDefOne(retval, ret, &err);
qmp_marshal_output_UserDefOne(retval, ret, errp);

out:
error_propagate(errp, err);
visit_free(v);
v = qapi_dealloc_visitor_new();
visit_start_struct(v, NULL, NULL, 0, NULL);
visit_type_q_obj_my_command_arg_members(v, &arg, NULL);
visit_end_struct(v, NULL);
visit_free(v);
}

[Uninteresting stuff omitted...]
$ cat qapi-generated/example-qapi-init-commands.h
[Uninteresting stuff omitted...]
Expand Down
22 changes: 9 additions & 13 deletions scripts/qapi/commands.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ def gen_call(name, arg_type, boxed, ret_type):
ret = mcgen('''
%(lhs)sqmp_%(c_name)s(%(args)s&err);
error_propagate(errp, err);
''',
c_name=c_name(name), args=argstr, lhs=lhs)
if ret_type:
Expand All @@ -55,7 +56,7 @@ def gen_call(name, arg_type, boxed, ret_type):
goto out;
}
qmp_marshal_output_%(c_name)s(retval, ret, &err);
qmp_marshal_output_%(c_name)s(retval, ret, errp);
''',
c_name=ret_type.c_name())
return ret
Expand All @@ -66,15 +67,12 @@ def gen_marshal_output(ret_type):
static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject **ret_out, Error **errp)
{
Error *err = NULL;
Visitor *v;
v = qobject_output_visitor_new(ret_out);
visit_type_%(c_name)s(v, "unused", &ret_in, &err);
if (!err) {
if (visit_type_%(c_name)s(v, "unused", &ret_in, errp)) {
visit_complete(v, ret_out);
}
error_propagate(errp, err);
visit_free(v);
v = qapi_dealloc_visitor_new();
visit_type_%(c_name)s(v, "unused", &ret_in, NULL);
Expand Down Expand Up @@ -104,6 +102,7 @@ def gen_marshal(name, arg_type, boxed, ret_type):
%(proto)s
{
Error *err = NULL;
bool ok = false;
Visitor *v;
''',
proto=build_marshal_proto(name))
Expand All @@ -123,28 +122,26 @@ def gen_marshal(name, arg_type, boxed, ret_type):
ret += mcgen('''
v = qobject_input_visitor_new(QOBJECT(args));
visit_start_struct(v, NULL, NULL, 0, &err);
if (err) {
if (!visit_start_struct(v, NULL, NULL, 0, errp)) {
goto out;
}
''')

if have_args:
ret += mcgen('''
visit_type_%(c_arg_type)s_members(v, &arg, &err);
if (!err) {
visit_check_struct(v, &err);
if (visit_type_%(c_arg_type)s_members(v, &arg, errp)) {
ok = visit_check_struct(v, errp);
}
''',
c_arg_type=arg_type.c_name())
else:
ret += mcgen('''
visit_check_struct(v, &err);
ok = visit_check_struct(v, errp);
''')

ret += mcgen('''
visit_end_struct(v, NULL);
if (err) {
if (!ok) {
goto out;
}
''')
Expand All @@ -154,7 +151,6 @@ def gen_marshal(name, arg_type, boxed, ret_type):
ret += mcgen('''
out:
error_propagate(errp, err);
visit_free(v);
''')

Expand Down

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