qapi: Add feature flags to commands

Similarly to features for struct types introduce the feature flags also
for commands. This will allow notifying management layers of fixes and
compatible changes in the behaviour of a command which may not be
detectable any other way.

The changes were heavily inspired by commit 6a8c0b51025.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191018081454.21369-3-armbru@redhat.com>

5 files changed, 49 insertions, 22 deletions

diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
index 898516b086..ab98e504f3 100644
--- a/scripts/qapi/commands.py
+++ b/scripts/qapi/commands.py
@@ -277,7 +277,8 @@ void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds);
         genc.add(gen_registry(self._regy.get_content(), self._prefix))
 
     def visit_command(self, name, info, ifcond, arg_type, ret_type, gen,
-                      success_response, boxed, allow_oob, allow_preconfig):
+                      success_response, boxed, allow_oob, allow_preconfig,
+                      features):
         if not gen:
             return
         # FIXME: If T is a user-defined type, the user is responsible
diff --git a/scripts/qapi/doc.py b/scripts/qapi/doc.py
index dc8919bab7..6d5726cf6e 100644
--- a/scripts/qapi/doc.py
+++ b/scripts/qapi/doc.py
@@ -249,12 +249,14 @@ class QAPISchemaGenDocVisitor(QAPISchemaVisitor):
                                body=texi_entity(doc, 'Members', ifcond)))
 
     def visit_command(self, name, info, ifcond, arg_type, ret_type, gen,
-                      success_response, boxed, allow_oob, allow_preconfig):
+                      success_response, boxed, allow_oob, allow_preconfig,
+                      features):
         doc = self.cur_doc
         if boxed:
             body = texi_body(doc)
             body += ('\n@b{Arguments:} the members of @code{%s}\n'
                      % arg_type.name)
+            body += texi_features(doc)
             body += texi_sections(doc, ifcond)
         else:
             body = texi_entity(doc, 'Arguments', ifcond)
diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
index 67cb2c2b6c..7c7394f835 100644
--- a/scripts/qapi/expr.py
+++ b/scripts/qapi/expr.py
@@ -185,6 +185,22 @@ def normalize_features(features):
                        for f in features]
 
 
+def check_features(features, info):
+    if features is None:
+        return
+    if not isinstance(features, list):
+        raise QAPISemError(info, "'features' must be an array")
+    for f in features:
+        source = "'features' member"
+        assert isinstance(f, dict)
+        check_keys(f, info, source, ['name'], ['if'])
+        check_name_is_str(f['name'], info, source)
+        source = "%s '%s'" % (source, f['name'])
+        check_name_str(f['name'], info, source)
+        check_if(f, info, source)
+        normalize_if(f)
+
+
 def normalize_enum(expr):
     if isinstance(expr['data'], list):
         expr['data'] = [m if isinstance(m, dict) else {'name': m}
@@ -217,23 +233,10 @@ def check_enum(expr, info):
 def check_struct(expr, info):
     name = expr['struct']
     members = expr['data']
-    features = expr.get('features')
 
     check_type(members, info, "'data'", allow_dict=name)
     check_type(expr.get('base'), info, "'base'")
-
-    if features:
-        if not isinstance(features, list):
-            raise QAPISemError(info, "'features' must be an array")
-        for f in features:
-            source = "'features' member"
-            assert isinstance(f, dict)
-            check_keys(f, info, source, ['name'], ['if'])
-            check_name_is_str(f['name'], info, source)
-            source = "%s '%s'" % (source, f['name'])
-            check_name_str(f['name'], info, source)
-            check_if(f, info, source)
-            normalize_if(f)
+    check_features(expr.get('features'), info)
 
 
 def check_union(expr, info):
@@ -283,6 +286,7 @@ def check_command(expr, info):
         raise QAPISemError(info, "'boxed': true requires 'data'")
     check_type(args, info, "'data'", allow_dict=not boxed)
     check_type(rets, info, "'returns'", allow_array=True)
+    check_features(expr.get('features'), info)
 
 
 def check_event(expr, info):
@@ -358,10 +362,11 @@ def check_exprs(exprs):
         elif meta == 'command':
             check_keys(expr, info, meta,
                        ['command'],
-                       ['data', 'returns', 'boxed', 'if',
+                       ['data', 'returns', 'boxed', 'if', 'features',
                         'gen', 'success-response', 'allow-oob',
                         'allow-preconfig'])
             normalize_members(expr.get('data'))
+            normalize_features(expr.get('features'))
             check_command(expr, info)
         elif meta == 'event':
             check_keys(expr, info, meta,
diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 4f257591de..b3a463dd8b 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -211,13 +211,18 @@ const QLitObject %(c_name)s = %(c_string)s;
                            for m in variants.variants]}, ifcond)
 
     def visit_command(self, name, info, ifcond, arg_type, ret_type, gen,
-                      success_response, boxed, allow_oob, allow_preconfig):
+                      success_response, boxed, allow_oob, allow_preconfig,
+                      features):
         arg_type = arg_type or self._schema.the_empty_object_type
         ret_type = ret_type or self._schema.the_empty_object_type
         obj = {'arg-type': self._use_type(arg_type),
                'ret-type': self._use_type(ret_type)}
         if allow_oob:
             obj['allow-oob'] = allow_oob
+
+        if features:
+            obj['features'] = [(f.name, {'if': f.ifcond}) for f in features]
+
         self._gen_qlit(name, 'command', obj, ifcond)
 
     def visit_event(self, name, info, ifcond, arg_type, boxed):
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 2913a0fef0..f7d68a35f4 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -110,7 +110,8 @@ class QAPISchemaVisitor(object):
         pass
 
     def visit_command(self, name, info, ifcond, arg_type, ret_type, gen,
-                      success_response, boxed, allow_oob, allow_preconfig):
+                      success_response, boxed, allow_oob, allow_preconfig,
+                      features):
         pass
 
     def visit_event(self, name, info, ifcond, arg_type, boxed):
@@ -659,10 +660,14 @@ class QAPISchemaCommand(QAPISchemaEntity):
     meta = 'command'
 
     def __init__(self, name, info, doc, ifcond, arg_type, ret_type,
-                 gen, success_response, boxed, allow_oob, allow_preconfig):
+                 gen, success_response, boxed, allow_oob, allow_preconfig,
+                 features):
         QAPISchemaEntity.__init__(self, name, info, doc, ifcond)
         assert not arg_type or isinstance(arg_type, str)
         assert not ret_type or isinstance(ret_type, str)
+        for f in features:
+            assert isinstance(f, QAPISchemaFeature)
+            f.set_defined_in(name)
         self._arg_type_name = arg_type
         self.arg_type = None
         self._ret_type_name = ret_type
@@ -672,6 +677,7 @@ class QAPISchemaCommand(QAPISchemaEntity):
         self.boxed = boxed
         self.allow_oob = allow_oob
         self.allow_preconfig = allow_preconfig
+        self.features = features
 
     def check(self, schema):
         QAPISchemaEntity.check(self, schema)
@@ -701,13 +707,19 @@ class QAPISchemaCommand(QAPISchemaEntity):
                         "command's 'returns' cannot take %s"
                         % self.ret_type.describe())
 
+        # Features are in a name space separate from members
+        seen = {}
+        for f in self.features:
+            f.check_clash(self.info, seen)
+
     def visit(self, visitor):
         QAPISchemaEntity.visit(self, visitor)
         visitor.visit_command(self.name, self.info, self.ifcond,
                               self.arg_type, self.ret_type,
                               self.gen, self.success_response,
                               self.boxed, self.allow_oob,
-                              self.allow_preconfig)
+                              self.allow_preconfig,
+                              self.features)
 
 
 class QAPISchemaEvent(QAPISchemaEntity):
@@ -984,6 +996,7 @@ class QAPISchema(object):
         allow_oob = expr.get('allow-oob', False)
         allow_preconfig = expr.get('allow-preconfig', False)
         ifcond = expr.get('if')
+        features = expr.get('features', [])
         if isinstance(data, OrderedDict):
             data = self._make_implicit_object_type(
                 name, info, doc, ifcond, 'arg', self._make_members(data, info))
@@ -992,7 +1005,8 @@ class QAPISchema(object):
             rets = self._make_array_type(rets[0], info)
         self._def_entity(QAPISchemaCommand(name, info, doc, ifcond, data, rets,
                                            gen, success_response,
-                                           boxed, allow_oob, allow_preconfig))
+                                           boxed, allow_oob, allow_preconfig,
+                                           self._make_features(features, info)))
 
     def _def_event(self, expr, info, doc):
         name = expr['event']