qemu-patch-raspberry4/scripts/qapi/events.py
John Snow 7137a96099 qapi: Prefer explicit relative imports
All of the QAPI include statements are changed to be package-aware, as
explicit relative imports.

A quirk of Python packages is that the name of the package exists only
*outside* of the package. This means that to a module inside of the qapi
folder, there is inherently no such thing as the "qapi" package. The
reason these imports work is because the "qapi" package exists in the
context of the caller -- the execution shim, where sys.path includes a
directory that has a 'qapi' folder in it.

When we write "from qapi import sibling", we are NOT referencing the folder
'qapi', but rather "any package named qapi in sys.path". If you should
so happen to have a 'qapi' package in your path, it will use *that*
package.

When we write "from .sibling import foo", we always reference explicitly
our sibling module; guaranteeing consistency in *where* we are importing
these modules from.

This can be useful when working with virtual environments and packages
in development mode. In development mode, a package is installed as a
series of symlinks that forwards to your same source files. The problem
arises because code quality checkers will follow "import qapi.x" to the
"installed" version instead of the sibling file and -- even though they
are the same file -- they have different module paths, and this causes
cyclic import problems, false positive type mismatch errors, and more.

It can also be useful when dealing with hierarchical packages, e.g. if
we allow qemu.core.qmp, qemu.qapi.parser, etc.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201009161558.107041-6-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2020-10-10 11:37:47 +02:00

207 lines
6 KiB
Python

"""
QAPI event generator
Copyright (c) 2014 Wenchao Xia
Copyright (c) 2015-2018 Red Hat Inc.
Authors:
Wenchao Xia <wenchaoqemu@gmail.com>
Markus Armbruster <armbru@redhat.com>
This work is licensed under the terms of the GNU GPL, version 2.
See the COPYING file in the top-level directory.
"""
from .common import *
from .gen import QAPISchemaModularCVisitor, ifcontext
from .schema import QAPISchemaEnumMember
from .types import gen_enum, gen_enum_lookup
def build_event_send_proto(name, arg_type, boxed):
return 'void qapi_event_send_%(c_name)s(%(param)s)' % {
'c_name': c_name(name.lower()),
'param': build_params(arg_type, boxed)}
def gen_event_send_decl(name, arg_type, boxed):
return mcgen('''
%(proto)s;
''',
proto=build_event_send_proto(name, arg_type, boxed))
# Declare and initialize an object 'qapi' using parameters from build_params()
def gen_param_var(typ):
assert not typ.variants
ret = mcgen('''
%(c_name)s param = {
''',
c_name=typ.c_name())
sep = ' '
for memb in typ.members:
ret += sep
sep = ', '
if memb.optional:
ret += 'has_' + c_name(memb.name) + sep
if memb.type.name == 'str':
# Cast away const added in build_params()
ret += '(char *)'
ret += c_name(memb.name)
ret += mcgen('''
};
''')
if not typ.is_implicit():
ret += mcgen('''
%(c_name)s *arg = &param;
''',
c_name=typ.c_name())
return ret
def gen_event_send(name, arg_type, boxed, event_enum_name, event_emit):
# FIXME: Our declaration of local variables (and of 'errp' in the
# parameter list) can collide with exploded members of the event's
# data type passed in as parameters. If this collision ever hits in
# practice, we can rename our local variables with a leading _ prefix,
# or split the code into a wrapper function that creates a boxed
# 'param' object then calls another to do the real work.
have_args = boxed or (arg_type and not arg_type.is_empty())
ret = mcgen('''
%(proto)s
{
QDict *qmp;
''',
proto=build_event_send_proto(name, arg_type, boxed))
if have_args:
ret += mcgen('''
QObject *obj;
Visitor *v;
''')
if not boxed:
ret += gen_param_var(arg_type)
ret += mcgen('''
qmp = qmp_event_build_dict("%(name)s");
''',
name=name)
if have_args:
ret += mcgen('''
v = qobject_output_visitor_new(&obj);
''')
if not arg_type.is_implicit():
ret += mcgen('''
visit_type_%(c_name)s(v, "%(name)s", &arg, &error_abort);
''',
name=name, c_name=arg_type.c_name())
else:
ret += mcgen('''
visit_start_struct(v, "%(name)s", NULL, 0, &error_abort);
visit_type_%(c_name)s_members(v, &param, &error_abort);
visit_check_struct(v, &error_abort);
visit_end_struct(v, NULL);
''',
name=name, c_name=arg_type.c_name())
ret += mcgen('''
visit_complete(v, &obj);
qdict_put_obj(qmp, "data", obj);
''')
ret += mcgen('''
%(event_emit)s(%(c_enum)s, qmp);
''',
event_emit=event_emit,
c_enum=c_enum_const(event_enum_name, name))
if have_args:
ret += mcgen('''
visit_free(v);
''')
ret += mcgen('''
qobject_unref(qmp);
}
''')
return ret
class QAPISchemaGenEventVisitor(QAPISchemaModularCVisitor):
def __init__(self, prefix):
super().__init__(
prefix, 'qapi-events',
' * Schema-defined QAPI/QMP events', None, __doc__)
self._event_enum_name = c_name(prefix + 'QAPIEvent', protect=False)
self._event_enum_members = []
self._event_emit_name = c_name(prefix + 'qapi_event_emit')
def _begin_user_module(self, name):
events = self._module_basename('qapi-events', name)
types = self._module_basename('qapi-types', name)
visit = self._module_basename('qapi-visit', name)
self._genc.add(mcgen('''
#include "qemu/osdep.h"
#include "%(prefix)sqapi-emit-events.h"
#include "%(events)s.h"
#include "%(visit)s.h"
#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qmp-event.h"
''',
events=events, visit=visit,
prefix=self._prefix))
self._genh.add(mcgen('''
#include "qapi/util.h"
#include "%(types)s.h"
''',
types=types))
def visit_end(self):
self._add_system_module('emit', ' * QAPI Events emission')
self._genc.preamble_add(mcgen('''
#include "qemu/osdep.h"
#include "%(prefix)sqapi-emit-events.h"
''',
prefix=self._prefix))
self._genh.preamble_add(mcgen('''
#include "qapi/util.h"
'''))
self._genh.add(gen_enum(self._event_enum_name,
self._event_enum_members))
self._genc.add(gen_enum_lookup(self._event_enum_name,
self._event_enum_members))
self._genh.add(mcgen('''
void %(event_emit)s(%(event_enum)s event, QDict *qdict);
''',
event_emit=self._event_emit_name,
event_enum=self._event_enum_name))
def visit_event(self, name, info, ifcond, features, arg_type, boxed):
with ifcontext(ifcond, self._genh, self._genc):
self._genh.add(gen_event_send_decl(name, arg_type, boxed))
self._genc.add(gen_event_send(name, arg_type, boxed,
self._event_enum_name,
self._event_emit_name))
# Note: we generate the enum member regardless of @ifcond, to
# keep the enumeration usable in target-independent code.
self._event_enum_members.append(QAPISchemaEnumMember(name, None))
def gen_events(schema, output_dir, prefix):
vis = QAPISchemaGenEventVisitor(prefix)
schema.visit(vis)
vis.write(output_dir)