qapi: Introduce a first class 'any' type

It's first class, because unlike '**', it actually works, i.e. doesn't
require 'gen': false.

'**' will go away next.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

docs/qapi-code-gen.txt

@@ -158,6 +158,7 @@ The following types are predefined, and map to C as follows:
   size      uint64_t   like uint64_t, except StringInputVisitor
                        accepts size suffixes
   bool      bool       JSON true or false
+  any       QObject *  any JSON value
 
 
 === Includes ===

include/qapi/visitor-impl.h

@@ -40,6 +40,8 @@ struct Visitor
     void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
     void (*type_number)(Visitor *v, double *obj, const char *name,
                         Error **errp);
+    void (*type_any)(Visitor *v, QObject **obj, const char *name,
+                     Error **errp);
 
     /* May be NULL */
     void (*optional)(Visitor *v, bool *present, const char *name,

include/qapi/visitor.h

@@ -58,6 +58,7 @@ void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp);
 void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp);
 void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp);
 void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp);
+void visit_type_any(Visitor *v, QObject **obj, const char *name, Error **errp);
 bool visit_start_union(Visitor *v, bool data_present, Error **errp);
 void visit_end_union(Visitor *v, bool data_present, Error **errp);
 

qapi/qapi-dealloc-visitor.c

@@ -151,6 +151,14 @@ static void qapi_dealloc_type_number(Visitor *v, double *obj, const char *name,
 {
 }
 
+static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
+                                       const char *name, Error **errp)
+{
+    if (obj) {
+        qobject_decref(*obj);
+    }
+}
+
 static void qapi_dealloc_type_size(Visitor *v, uint64_t *obj, const char *name,
                                    Error **errp)
 {
@@ -216,6 +224,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.type_bool = qapi_dealloc_type_bool;
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
+    v->visitor.type_any = qapi_dealloc_type_anything;
     v->visitor.type_size = qapi_dealloc_type_size;
     v->visitor.start_union = qapi_dealloc_start_union;
 

qapi/qapi-visit-core.c

@@ -260,6 +260,12 @@ void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp)
     v->type_number(v, obj, name, errp);
 }
 
+void visit_type_any(Visitor *v, QObject **obj, const char *name,
+                    Error **errp)
+{
+    v->type_any(v, obj, name, errp);
+}
+
 void output_type_enum(Visitor *v, int *obj, const char * const strings[],
                       const char *kind, const char *name,
                       Error **errp)

qapi/qmp-input-visitor.c

@@ -286,6 +286,16 @@ static void qmp_input_type_number(Visitor *v, double *obj, const char *name,
     }
 }
 
+static void qmp_input_type_any(Visitor *v, QObject **obj, const char *name,
+                               Error **errp)
+{
+    QmpInputVisitor *qiv = to_qiv(v);
+    QObject *qobj = qmp_input_get_object(qiv, name, true);
+
+    qobject_incref(qobj);
+    *obj = qobj;
+}
+
 static void qmp_input_optional(Visitor *v, bool *present, const char *name,
                                Error **errp)
 {
@@ -329,6 +339,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.type_bool = qmp_input_type_bool;
     v->visitor.type_str = qmp_input_type_str;
     v->visitor.type_number = qmp_input_type_number;
+    v->visitor.type_any = qmp_input_type_any;
     v->visitor.optional = qmp_input_optional;
     v->visitor.get_next_type = qmp_input_get_next_type;
 

qapi/qmp-output-visitor.c

@@ -190,6 +190,14 @@ static void qmp_output_type_number(Visitor *v, double *obj, const char *name,
     qmp_output_add(qov, name, qfloat_from_double(*obj));
 }
 
+static void qmp_output_type_any(Visitor *v, QObject **obj, const char *name,
+                                Error **errp)
+{
+    QmpOutputVisitor *qov = to_qov(v);
+    qobject_incref(*obj);
+    qmp_output_add_obj(qov, name, *obj);
+}
+
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
     QObject *obj = qmp_output_first(qov);
@@ -237,6 +245,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.type_bool = qmp_output_type_bool;
     v->visitor.type_str = qmp_output_type_str;
     v->visitor.type_number = qmp_output_type_number;
+    v->visitor.type_any = qmp_output_type_any;
 
     QTAILQ_INIT(&v->stack);
 

scripts/qapi-types.py

@@ -327,6 +327,7 @@ fdef.write(mcgen('''
 fdecl.write(mcgen('''
 #include <stdbool.h>
 #include <stdint.h>
+#include "qapi/qmp/qobject.h"
 '''))
 
 schema = QAPISchema(input_file)

scripts/qapi.py

@@ -33,6 +33,7 @@ builtin_types = {
     'uint32':   'QTYPE_QINT',
     'uint64':   'QTYPE_QINT',
     'size':     'QTYPE_QINT',
+    'any':      None,           # any qtype_code possible, actually
 }
 
 # Whitelist of commands allowed to return a non-dictionary
@@ -1102,8 +1103,7 @@ class QAPISchema(object):
     def _def_builtin_type(self, name, json_type, c_type, c_null):
         self._def_entity(QAPISchemaBuiltinType(name, json_type,
                                                c_type, c_null))
-        if name != '**':
-            self._make_array_type(name)         # TODO really needed?
+        self._make_array_type(name)     # TODO really needed?
 
     def _def_predefineds(self):
         for t in [('str',    'string',  'char' + pointer_suffix, 'NULL'),
@@ -1119,8 +1119,9 @@ class QAPISchema(object):
                   ('uint64', 'int',     'uint64_t', '0'),
                   ('size',   'int',     'uint64_t', '0'),
                   ('bool',   'boolean', 'bool',     'false'),
-                  ('**',     'value',   None,       None)]:
+                  ('any',    'value',   'QObject' + pointer_suffix, 'NULL')]:
             self._def_builtin_type(*t)
+        self._entity_dict['**'] = self.lookup_type('any') # TODO drop this alias
 
     def _make_implicit_enum_type(self, name, values):
         name = name + 'Kind'
@@ -1270,6 +1271,8 @@ class QAPISchema(object):
     def visit(self, visitor):
         visitor.visit_begin(self)
         for name in sorted(self._entity_dict.keys()):
+            if self._entity_dict[name].name != name:
+                continue        # ignore alias TODO drop alias and remove
             self._entity_dict[name].visit(visitor)
         visitor.visit_end()
 

tests/Makefile

@@ -239,6 +239,7 @@ check-qapi-schema-y := $(addprefix tests/qapi-schema/, \
 	args-array-empty.json args-array-unknown.json args-int.json \
 	args-unknown.json args-member-unknown.json args-member-array.json \
 	args-member-array-bad.json args-alternate.json args-union.json \
+	args-any.json \
 	returns-array-bad.json returns-int.json returns-dict.json \
 	returns-unknown.json returns-alternate.json returns-whitelist.json \
 	missing-colon.json missing-comma-list.json missing-comma-object.json \
@@ -255,7 +256,7 @@ check-qapi-schema-y := $(addprefix tests/qapi-schema/, \
 	flat-union-invalid-branch-key.json flat-union-reverse-define.json \
 	flat-union-string-discriminator.json union-base-no-discriminator.json \
 	flat-union-bad-discriminator.json flat-union-bad-base.json \
-	flat-union-base-star.json \
+	flat-union-base-any.json \
 	flat-union-array-branch.json flat-union-int-branch.json \
 	flat-union-base-union.json flat-union-branch-clash.json \
 	alternate-nested.json alternate-unknown.json alternate-clash.json \

tests/qapi-schema/args-any.err

@@ -0,0 +1 @@
+tests/qapi-schema/args-any.json:2: 'data' for command 'oops' cannot use built-in type 'any'

tests/qapi-schema/args-any.json

@@ -0,0 +1,2 @@
+# we do not allow an 'any' argument
+{ 'command': 'oops', 'data': 'any' }

tests/qapi-schema/flat-union-base-any.err

@@ -0,0 +1 @@
+tests/qapi-schema/flat-union-base-any.json:8: Base 'any' is not a valid struct

tests/qapi-schema/flat-union-base-any.exit

@@ -0,0 +1 @@
+1

tests/qapi-schema/flat-union-base-any.json

@@ -6,7 +6,7 @@
 { 'struct': 'TestTypeB',
   'data': { 'integer': 'int' } }
 { 'union': 'TestUnion',
-  'base': '**',
+  'base': 'any',
   'discriminator': 'enum1',
   'data': { 'value1': 'TestTypeA',
             'value2': 'TestTypeB' } }

tests/qapi-schema/flat-union-base-star.err

@@ -1 +0,0 @@
-tests/qapi-schema/flat-union-base-star.json:8: Base '**' is not a valid struct

tests/qapi-schema/qapi-schema-test.json

@@ -78,7 +78,8 @@
             'number': ['number'],
             'boolean': ['bool'],
             'string': ['str'],
-            'sizes': ['size'] } }
+            'sizes': ['size'],
+            'any': ['any'] } }
 
 # testing commands
 { 'command': 'user_def_cmd', 'data': {} }
@@ -88,6 +89,8 @@
   'returns': 'UserDefTwo' }
 { 'command': 'user_def_cmd3', 'data': {'a': 'int', '*b': 'int' },
   'returns': 'int' }
+# note: command name 'guest-sync' chosen to avoid "cannot use built-in" error
+{ 'command': 'guest-sync', 'data': { 'arg': 'any' }, 'returns': 'any' }
 
 # For testing integer range flattening in opts-visitor. The following schema
 # corresponds to the option format: