6a8c0b5102
Sometimes, the behaviour of QEMU changes without a change in the QMP
syntax (usually by allowing values or operations that previously
resulted in an error). QMP clients may still need to know whether
they can rely on the changed behavior.
Let's add feature flags to the QAPI schema language, so that we can make
such changes visible with schema introspection.
An example for a schema definition using feature flags looks like this:
{ 'struct': 'TestType',
'data': { 'number': 'int' },
'features': [ 'allow-negative-numbers' ] }
Introspection information then looks like this:
{ "name": "TestType", "meta-type": "object",
"members": [
{ "name": "number", "type": "int" } ],
"features": [ "allow-negative-numbers" ] }
This patch implements feature flags only for struct types. We'll
implement them more widely as needed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20190606153803.5278-2-armbru@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
260 lines
7.1 KiB
Python
260 lines
7.1 KiB
Python
"""
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QAPI types generator
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Copyright IBM, Corp. 2011
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Copyright (c) 2013-2018 Red Hat Inc.
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Authors:
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Anthony Liguori <aliguori@us.ibm.com>
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Michael Roth <mdroth@linux.vnet.ibm.com>
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Markus Armbruster <armbru@redhat.com>
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This work is licensed under the terms of the GNU GPL, version 2.
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# See the COPYING file in the top-level directory.
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"""
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from qapi.common import *
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# variants must be emitted before their container; track what has already
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# been output
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objects_seen = set()
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def gen_fwd_object_or_array(name):
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return mcgen('''
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typedef struct %(c_name)s %(c_name)s;
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''',
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c_name=c_name(name))
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def gen_array(name, element_type):
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return mcgen('''
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struct %(c_name)s {
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%(c_name)s *next;
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%(c_type)s value;
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};
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''',
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c_name=c_name(name), c_type=element_type.c_type())
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def gen_struct_members(members):
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ret = ''
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for memb in members:
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ret += gen_if(memb.ifcond)
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if memb.optional:
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ret += mcgen('''
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bool has_%(c_name)s;
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''',
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c_name=c_name(memb.name))
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ret += mcgen('''
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%(c_type)s %(c_name)s;
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''',
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c_type=memb.type.c_type(), c_name=c_name(memb.name))
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ret += gen_endif(memb.ifcond)
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return ret
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def gen_object(name, ifcond, base, members, variants):
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if name in objects_seen:
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return ''
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objects_seen.add(name)
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ret = ''
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if variants:
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for v in variants.variants:
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if isinstance(v.type, QAPISchemaObjectType):
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ret += gen_object(v.type.name, v.type.ifcond, v.type.base,
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v.type.local_members, v.type.variants)
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ret += mcgen('''
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''')
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ret += gen_if(ifcond)
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ret += mcgen('''
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struct %(c_name)s {
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''',
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c_name=c_name(name))
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if base:
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if not base.is_implicit():
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ret += mcgen('''
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/* Members inherited from %(c_name)s: */
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''',
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c_name=base.c_name())
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ret += gen_struct_members(base.members)
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if not base.is_implicit():
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ret += mcgen('''
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/* Own members: */
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''')
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ret += gen_struct_members(members)
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if variants:
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ret += gen_variants(variants)
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# Make sure that all structs have at least one member; this avoids
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# potential issues with attempting to malloc space for zero-length
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# structs in C, and also incompatibility with C++ (where an empty
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# struct is size 1).
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if (not base or base.is_empty()) and not members and not variants:
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ret += mcgen('''
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char qapi_dummy_for_empty_struct;
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''')
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ret += mcgen('''
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};
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''')
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ret += gen_endif(ifcond)
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return ret
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def gen_upcast(name, base):
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# C makes const-correctness ugly. We have to cast away const to let
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# this function work for both const and non-const obj.
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return mcgen('''
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static inline %(base)s *qapi_%(c_name)s_base(const %(c_name)s *obj)
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{
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return (%(base)s *)obj;
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}
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''',
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c_name=c_name(name), base=base.c_name())
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def gen_variants(variants):
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ret = mcgen('''
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union { /* union tag is @%(c_name)s */
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''',
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c_name=c_name(variants.tag_member.name))
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for var in variants.variants:
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if var.type.name == 'q_empty':
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continue
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ret += gen_if(var.ifcond)
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ret += mcgen('''
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%(c_type)s %(c_name)s;
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''',
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c_type=var.type.c_unboxed_type(),
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c_name=c_name(var.name))
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ret += gen_endif(var.ifcond)
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ret += mcgen('''
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} u;
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''')
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return ret
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def gen_type_cleanup_decl(name):
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ret = mcgen('''
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void qapi_free_%(c_name)s(%(c_name)s *obj);
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''',
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c_name=c_name(name))
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return ret
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def gen_type_cleanup(name):
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ret = mcgen('''
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void qapi_free_%(c_name)s(%(c_name)s *obj)
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{
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Visitor *v;
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if (!obj) {
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return;
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}
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v = qapi_dealloc_visitor_new();
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visit_type_%(c_name)s(v, NULL, &obj, NULL);
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visit_free(v);
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}
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''',
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c_name=c_name(name))
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return ret
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class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
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def __init__(self, prefix):
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QAPISchemaModularCVisitor.__init__(
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self, prefix, 'qapi-types', ' * Schema-defined QAPI types',
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__doc__)
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self._add_system_module(None, ' * Built-in QAPI types')
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self._genc.preamble_add(mcgen('''
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#include "qemu/osdep.h"
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#include "qapi/dealloc-visitor.h"
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#include "qapi/qapi-builtin-types.h"
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#include "qapi/qapi-builtin-visit.h"
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'''))
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self._genh.preamble_add(mcgen('''
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#include "qapi/util.h"
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'''))
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def _begin_user_module(self, name):
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types = self._module_basename('qapi-types', name)
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visit = self._module_basename('qapi-visit', name)
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self._genc.preamble_add(mcgen('''
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#include "qemu/osdep.h"
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#include "qapi/dealloc-visitor.h"
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#include "%(types)s.h"
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#include "%(visit)s.h"
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''',
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types=types, visit=visit))
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self._genh.preamble_add(mcgen('''
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#include "qapi/qapi-builtin-types.h"
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'''))
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def visit_begin(self, schema):
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# gen_object() is recursive, ensure it doesn't visit the empty type
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objects_seen.add(schema.the_empty_object_type.name)
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def _gen_type_cleanup(self, name):
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self._genh.add(gen_type_cleanup_decl(name))
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self._genc.add(gen_type_cleanup(name))
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def visit_enum_type(self, name, info, ifcond, members, prefix):
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with ifcontext(ifcond, self._genh, self._genc):
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self._genh.preamble_add(gen_enum(name, members, prefix))
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self._genc.add(gen_enum_lookup(name, members, prefix))
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def visit_array_type(self, name, info, ifcond, element_type):
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with ifcontext(ifcond, self._genh, self._genc):
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self._genh.preamble_add(gen_fwd_object_or_array(name))
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self._genh.add(gen_array(name, element_type))
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self._gen_type_cleanup(name)
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def visit_object_type(self, name, info, ifcond, base, members, variants,
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features):
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# Nothing to do for the special empty builtin
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if name == 'q_empty':
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return
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with ifcontext(ifcond, self._genh):
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self._genh.preamble_add(gen_fwd_object_or_array(name))
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self._genh.add(gen_object(name, ifcond, base, members, variants))
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with ifcontext(ifcond, self._genh, self._genc):
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if base and not base.is_implicit():
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self._genh.add(gen_upcast(name, base))
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# TODO Worth changing the visitor signature, so we could
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# directly use rather than repeat type.is_implicit()?
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if not name.startswith('q_'):
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# implicit types won't be directly allocated/freed
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self._gen_type_cleanup(name)
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def visit_alternate_type(self, name, info, ifcond, variants):
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with ifcontext(ifcond, self._genh):
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self._genh.preamble_add(gen_fwd_object_or_array(name))
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self._genh.add(gen_object(name, ifcond, None,
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[variants.tag_member], variants))
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with ifcontext(ifcond, self._genh, self._genc):
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self._gen_type_cleanup(name)
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def gen_types(schema, output_dir, prefix, opt_builtins):
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vis = QAPISchemaGenTypeVisitor(prefix)
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schema.visit(vis)
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vis.write(output_dir, opt_builtins)
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