From 23ab6d81f99f3164b09ca3d5f5128218dc1db9c2 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Sun, 25 Feb 2018 20:22:00 -0500 Subject: [PATCH] qapi: Implement boxed types for commands/events Turn on the ability to pass command and event arguments in a single boxed parameter, which must name a non-empty type (although the type can be a struct with all optional members). For structs, it makes it possible to pass a single qapi type instead of a breakout of all struct members (useful if the arguments are already in a struct or if the number of members is large); for other complex types, it is now possible to use a union or alternate as the data for a command or event. The empty type may be technically feasible if needed down the road, but it's easier to forbid it now and relax things to allow it later, than it is to allow it now and have to special case how the generated 'q_empty' type is handled (see commit 7ce106a9 for reasons why nothing is generated for the empty type). An alternate type is never considered empty, but now that a boxed type can be either an object or an alternate, we have to provide a trivial QAPISchemaAlternateType.is_empty(). The new call to arg_type.is_empty() during QAPISchemaCommand.check() requires that we first check the type in question; but there is no chance of introducing a cycle since objects do not refer back to commands. We still have a split in syntax checking between ad-hoc parsing up front (merely validates that 'boxed' has a sane value) and during .check() methods (if 'boxed' is set, then 'data' must name a non-empty user-defined type). Generated code is unchanged, as long as no client uses the new feature. Backports commit c818408e449ea55371253bd4def1c1dc87b7bb03 from qemu --- qemu/scripts/qapi-event.py | 5 ++- qemu/scripts/qapi.py | 63 ++++++++++++++++++++++++++++++-------- 2 files changed, 54 insertions(+), 14 deletions(-) diff --git a/qemu/scripts/qapi-event.py b/qemu/scripts/qapi-event.py index abec6289..30e64584 100644 --- a/qemu/scripts/qapi-event.py +++ b/qemu/scripts/qapi-event.py @@ -79,7 +79,10 @@ def gen_event_send(name, arg_type, boxed): QObject *obj; Visitor *v; ''') - ret += gen_param_var(arg_type) + if not boxed: + ret += gen_param_var(arg_type) + else: + assert not boxed ret += mcgen(''' diff --git a/qemu/scripts/qapi.py b/qemu/scripts/qapi.py index 3b8703a5..570a74ec 100644 --- a/qemu/scripts/qapi.py +++ b/qemu/scripts/qapi.py @@ -526,10 +526,14 @@ def check_type(expr_info, source, value, allow_array=False, def check_command(expr, expr_info): name = expr['command'] + boxed = expr.get('boxed', False) + args_meta = ['struct'] + if boxed: + args_meta += ['union', 'alternate'] check_type(expr_info, "'data' for command '%s'" % name, - expr.get('data'), allow_dict=True, allow_optional=True, - allow_metas=['struct']) + expr.get('data'), allow_dict=not boxed, allow_optional=True, + allow_metas=args_meta) returns_meta = ['union', 'struct'] if name in returns_whitelist: returns_meta += ['built-in', 'alternate', 'enum'] @@ -541,11 +545,15 @@ def check_command(expr, expr_info): def check_event(expr, expr_info): global events name = expr['event'] + boxed = expr.get('boxed', False) + meta = ['struct'] + if boxed: + meta += ['union', 'alternate'] events.append(name) check_type(expr_info, "'data' for event '%s'" % name, - expr.get('data'), allow_dict=True, allow_optional=True, - allow_metas=['struct']) + expr.get('data'), allow_dict=not boxed, allow_optional=True, + allow_metas=meta) def check_union(expr, expr_info): @@ -699,6 +707,10 @@ def check_keys(expr_elem, meta, required, optional=[]): raise QAPIExprError(info, "'%s' of %s '%s' should only use false value" % (key, meta, name)) + if key == 'boxed' and value is not True: + raise QAPIExprError(info, + "'%s' of %s '%s' should only use true value" + % (key, meta, name)) for key in required: if key not in expr: raise QAPIExprError(info, @@ -730,10 +742,10 @@ def check_exprs(exprs): add_struct(expr, info) elif 'command' in expr: check_keys(expr_elem, 'command', [], - ['data', 'returns', 'gen', 'success-response']) + ['data', 'returns', 'gen', 'success-response', 'boxed']) add_name(expr['command'], info, 'command') elif 'event' in expr: - check_keys(expr_elem, 'event', [], ['data']) + check_keys(expr_elem, 'event', [], ['data', 'boxed']) add_name(expr['event'], info, 'event') else: raise QAPIExprError(expr_elem['info'], @@ -1177,6 +1189,9 @@ class QAPISchemaAlternateType(QAPISchemaType): def visit(self, visitor): visitor.visit_alternate_type(self.name, self.info, self.variants) + def is_empty(self): + return False + class QAPISchemaCommand(QAPISchemaEntity): def __init__(self, name, info, arg_type, ret_type, gen, success_response, @@ -1195,9 +1210,19 @@ class QAPISchemaCommand(QAPISchemaEntity): def check(self, schema): if self._arg_type_name: self.arg_type = schema.lookup_type(self._arg_type_name) - assert isinstance(self.arg_type, QAPISchemaObjectType) - assert not self.arg_type.variants # not implemented - assert not self.boxed # not implemented + assert (isinstance(self.arg_type, QAPISchemaObjectType) or + isinstance(self.arg_type, QAPISchemaAlternateType)) + self.arg_type.check(schema) + if self.boxed: + if self.arg_type.is_empty(): + raise QAPIExprError(self.info, + "Cannot use 'boxed' with empty type") + else: + assert not isinstance(self.arg_type, QAPISchemaAlternateType) + assert not self.arg_type.variants + elif self.boxed: + raise QAPIExprError(self.info, + "Use of 'boxed' requires 'data'") if self._ret_type_name: self.ret_type = schema.lookup_type(self._ret_type_name) assert isinstance(self.ret_type, QAPISchemaType) @@ -1219,9 +1244,19 @@ class QAPISchemaEvent(QAPISchemaEntity): def check(self, schema): if self._arg_type_name: self.arg_type = schema.lookup_type(self._arg_type_name) - assert isinstance(self.arg_type, QAPISchemaObjectType) - assert not self.arg_type.variants # not implemented - assert not self.boxed # not implemented + assert (isinstance(self.arg_type, QAPISchemaObjectType) or + isinstance(self.arg_type, QAPISchemaAlternateType)) + self.arg_type.check(schema) + if self.boxed: + if self.arg_type.is_empty(): + raise QAPIExprError(self.info, + "Cannot use 'boxed' with empty type") + else: + assert not isinstance(self.arg_type, QAPISchemaAlternateType) + assert not self.arg_type.variants + elif self.boxed: + raise QAPIExprError(self.info, + "Use of 'boxed' requires 'data'") def visit(self, visitor): visitor.visit_event(self.name, self.info, self.arg_type, self.boxed) @@ -1661,9 +1696,11 @@ extern const char *const %(c_name)s_lookup[]; def gen_params(arg_type, boxed, extra): if not arg_type: + assert not boxed return extra if boxed: - assert False # not implemented + ret += '%s arg' % arg_type.c_param_type() + sep = ', ' else: assert not arg_type.variants for memb in arg_type.members: