unicorn/qemu/scripts/qapi-event.py

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#
# QAPI event generator
#
# Copyright (c) 2014 Wenchao Xia
qapi: Improve generated event use of qapi visitor All other successful clients of visit_start_struct() were paired with an unconditional visit_end_struct(); but the generated code for events was relying on qmp_output_visitor_cleanup() to work on an incomplete visit. Alter the code to guarantee that the struct is completed, which will make a future patch to split visit_end_struct() easier to reason about. While at it, drop some assertions and comments that are not present in other uses of the qmp output visitor, and pass NULL rather than "" as the 'kind' parameter (matching most other uses where obj is NULL). The changes to the generated code look like: | qmp = qmp_event_build_dict("DEVICE_TRAY_MOVED"); | | qov = qmp_output_visitor_new(); |- g_assert(qov); |- | v = qmp_output_get_visitor(qov); |- g_assert(v); | |- /* Fake visit, as if all members are under a structure */ |- visit_start_struct(v, NULL, "", "DEVICE_TRAY_MOVED", 0, &err); |+ visit_start_struct(v, NULL, NULL, "DEVICE_TRAY_MOVED", 0, &err); | if (err) { | goto out; | } | visit_type_str(v, (char **)&device, "device", &err); | if (err) { |- goto out; |+ goto out_obj; | } | visit_type_bool(v, &tray_open, "tray-open", &err); | if (err) { |- goto out; |+ goto out_obj; | } |- visit_end_struct(v, &err); |+out_obj: |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } | | obj = qmp_output_get_qobject(qov); |- g_assert(obj != NULL); |+ g_assert(obj); | | qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_DEVICE_TRAY_MOVED, qmp, &err); Note that the 'goto out_obj' with no intervening code before the label, as well as the construct of 'err ? NULL : &err', are both a bit unusual but also temporary; they get fixed in a later patch that splits visit_end_struct() to drop its errp parameter by moving some checking before the label. But until that time, this was the simplest way to avoid the appearance of passing a possibly-set error to visit_end_struct(), even though actual code inspection shows that visit_end_struct() for a QMP output visitor will never set an error. Backports commit a16e3e5c5825c90887a863513916f93eeec16c55 from qemu
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# Copyright (c) 2015-2016 Red Hat Inc.
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#
# Authors:
# Wenchao Xia <wenchaoqemu@gmail.com>
# Markus Armbruster <armbru@redhat.com>
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#
# This work is licensed under the terms of the GNU GPL, version 2.
# See the COPYING file in the top-level directory.
from qapi import *
def gen_event_send_proto(name, arg_type):
return 'void qapi_event_send_%(c_name)s(%(param)s)' % {
'c_name': c_name(name.lower()),
'param': gen_params(arg_type, 'Error **errp')}
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def gen_event_send_decl(name, arg_type):
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return mcgen('''
%(proto)s;
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''',
proto=gen_event_send_proto(name, arg_type))
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def gen_event_send(name, arg_type):
ret = mcgen('''
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%(proto)s
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{
QDict *qmp;
Error *err = NULL;
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QMPEventFuncEmit emit;
''',
proto=gen_event_send_proto(name, arg_type))
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if arg_type and arg_type.members:
ret += mcgen('''
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QmpOutputVisitor *qov;
Visitor *v;
QObject *obj;
''')
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ret += mcgen('''
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emit = qmp_event_get_func_emit();
if (!emit) {
return;
}
qmp = qmp_event_build_dict("%(name)s");
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''',
name=name)
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if arg_type and arg_type.members:
ret += mcgen('''
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qov = qmp_output_visitor_new();
v = qmp_output_get_visitor(qov);
qapi: Swap visit_* arguments for consistent 'name' placement JSON uses "name":value, but many of our visitor interfaces were called with visit_type_FOO(v, &value, name, errp). This can be a bit confusing to have to mentally swap the parameter order to match JSON order. It's particularly bad for visit_start_struct(), where the 'name' parameter is smack in the middle of the otherwise-related group of 'obj, kind, size' parameters! It's time to do a global swap of the parameter ordering, so that the 'name' parameter is always immediately after the Visitor argument. Additional reason in favor of the swap: the existing include/qjson.h prefers listing 'name' first in json_prop_*(), and I have plans to unify that file with the qapi visitors; listing 'name' first in qapi will minimize churn to the (admittedly few) qjson.h clients. Later patches will then fix docs, object.h, visitor-impl.h, and those clients to match. Done by first patching scripts/qapi*.py by hand to make generated files do what I want, then by running the following Coccinelle script to affect the rest of the code base: $ spatch --sp-file script `git grep -l '\bvisit_' -- '**/*.[ch]'` I then had to apply some touchups (Coccinelle insisted on TAB indentation in visitor.h, and botched the signature of visit_type_enum() by rewriting 'const char *const strings[]' to the syntactically invalid 'const char*const[] strings'). The movement of parameters is sufficient to provoke compiler errors if any callers were missed. // Part 1: Swap declaration order @@ type TV, TErr, TObj, T1, T2; identifier OBJ, ARG1, ARG2; @@ void visit_start_struct -(TV v, TObj OBJ, T1 ARG1, const char *name, T2 ARG2, TErr errp) +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp) { ... } @@ type bool, TV, T1; identifier ARG1; @@ bool visit_optional -(TV v, T1 ARG1, const char *name) +(TV v, const char *name, T1 ARG1) { ... } @@ type TV, TErr, TObj, T1; identifier OBJ, ARG1; @@ void visit_get_next_type -(TV v, TObj OBJ, T1 ARG1, const char *name, TErr errp) +(TV v, const char *name, TObj OBJ, T1 ARG1, TErr errp) { ... } @@ type TV, TErr, TObj, T1, T2; identifier OBJ, ARG1, ARG2; @@ void visit_type_enum -(TV v, TObj OBJ, T1 ARG1, T2 ARG2, const char *name, TErr errp) +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp) { ... } @@ type TV, TErr, TObj; identifier OBJ; identifier VISIT_TYPE =~ "^visit_type_"; @@ void VISIT_TYPE -(TV v, TObj OBJ, const char *name, TErr errp) +(TV v, const char *name, TObj OBJ, TErr errp) { ... } // Part 2: swap caller order @@ expression V, NAME, OBJ, ARG1, ARG2, ERR; identifier VISIT_TYPE =~ "^visit_type_"; @@ ( -visit_start_struct(V, OBJ, ARG1, NAME, ARG2, ERR) +visit_start_struct(V, NAME, OBJ, ARG1, ARG2, ERR) | -visit_optional(V, ARG1, NAME) +visit_optional(V, NAME, ARG1) | -visit_get_next_type(V, OBJ, ARG1, NAME, ERR) +visit_get_next_type(V, NAME, OBJ, ARG1, ERR) | -visit_type_enum(V, OBJ, ARG1, ARG2, NAME, ERR) +visit_type_enum(V, NAME, OBJ, ARG1, ARG2, ERR) | -VISIT_TYPE(V, OBJ, NAME, ERR) +VISIT_TYPE(V, NAME, OBJ, ERR) ) Backports commit 51e72bc1dd6ace6e91d675f41a1f09bd00ab8043 from qemu
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visit_start_struct(v, "%(name)s", NULL, NULL, 0, &err);
''',
name=name)
ret += gen_err_check()
qapi: Improve generated event use of qapi visitor All other successful clients of visit_start_struct() were paired with an unconditional visit_end_struct(); but the generated code for events was relying on qmp_output_visitor_cleanup() to work on an incomplete visit. Alter the code to guarantee that the struct is completed, which will make a future patch to split visit_end_struct() easier to reason about. While at it, drop some assertions and comments that are not present in other uses of the qmp output visitor, and pass NULL rather than "" as the 'kind' parameter (matching most other uses where obj is NULL). The changes to the generated code look like: | qmp = qmp_event_build_dict("DEVICE_TRAY_MOVED"); | | qov = qmp_output_visitor_new(); |- g_assert(qov); |- | v = qmp_output_get_visitor(qov); |- g_assert(v); | |- /* Fake visit, as if all members are under a structure */ |- visit_start_struct(v, NULL, "", "DEVICE_TRAY_MOVED", 0, &err); |+ visit_start_struct(v, NULL, NULL, "DEVICE_TRAY_MOVED", 0, &err); | if (err) { | goto out; | } | visit_type_str(v, (char **)&device, "device", &err); | if (err) { |- goto out; |+ goto out_obj; | } | visit_type_bool(v, &tray_open, "tray-open", &err); | if (err) { |- goto out; |+ goto out_obj; | } |- visit_end_struct(v, &err); |+out_obj: |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } | | obj = qmp_output_get_qobject(qov); |- g_assert(obj != NULL); |+ g_assert(obj); | | qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_DEVICE_TRAY_MOVED, qmp, &err); Note that the 'goto out_obj' with no intervening code before the label, as well as the construct of 'err ? NULL : &err', are both a bit unusual but also temporary; they get fixed in a later patch that splits visit_end_struct() to drop its errp parameter by moving some checking before the label. But until that time, this was the simplest way to avoid the appearance of passing a possibly-set error to visit_end_struct(), even though actual code inspection shows that visit_end_struct() for a QMP output visitor will never set an error. Backports commit a16e3e5c5825c90887a863513916f93eeec16c55 from qemu
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ret += gen_visit_fields(arg_type.members, need_cast=True,
label='out_obj')
ret += mcgen('''
qapi: Improve generated event use of qapi visitor All other successful clients of visit_start_struct() were paired with an unconditional visit_end_struct(); but the generated code for events was relying on qmp_output_visitor_cleanup() to work on an incomplete visit. Alter the code to guarantee that the struct is completed, which will make a future patch to split visit_end_struct() easier to reason about. While at it, drop some assertions and comments that are not present in other uses of the qmp output visitor, and pass NULL rather than "" as the 'kind' parameter (matching most other uses where obj is NULL). The changes to the generated code look like: | qmp = qmp_event_build_dict("DEVICE_TRAY_MOVED"); | | qov = qmp_output_visitor_new(); |- g_assert(qov); |- | v = qmp_output_get_visitor(qov); |- g_assert(v); | |- /* Fake visit, as if all members are under a structure */ |- visit_start_struct(v, NULL, "", "DEVICE_TRAY_MOVED", 0, &err); |+ visit_start_struct(v, NULL, NULL, "DEVICE_TRAY_MOVED", 0, &err); | if (err) { | goto out; | } | visit_type_str(v, (char **)&device, "device", &err); | if (err) { |- goto out; |+ goto out_obj; | } | visit_type_bool(v, &tray_open, "tray-open", &err); | if (err) { |- goto out; |+ goto out_obj; | } |- visit_end_struct(v, &err); |+out_obj: |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } | | obj = qmp_output_get_qobject(qov); |- g_assert(obj != NULL); |+ g_assert(obj); | | qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_DEVICE_TRAY_MOVED, qmp, &err); Note that the 'goto out_obj' with no intervening code before the label, as well as the construct of 'err ? NULL : &err', are both a bit unusual but also temporary; they get fixed in a later patch that splits visit_end_struct() to drop its errp parameter by moving some checking before the label. But until that time, this was the simplest way to avoid the appearance of passing a possibly-set error to visit_end_struct(), even though actual code inspection shows that visit_end_struct() for a QMP output visitor will never set an error. Backports commit a16e3e5c5825c90887a863513916f93eeec16c55 from qemu
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out_obj:
visit_end_struct(v, err ? NULL : &err);
if (err) {
goto out;
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}
obj = qmp_output_get_qobject(qov);
qapi: Improve generated event use of qapi visitor All other successful clients of visit_start_struct() were paired with an unconditional visit_end_struct(); but the generated code for events was relying on qmp_output_visitor_cleanup() to work on an incomplete visit. Alter the code to guarantee that the struct is completed, which will make a future patch to split visit_end_struct() easier to reason about. While at it, drop some assertions and comments that are not present in other uses of the qmp output visitor, and pass NULL rather than "" as the 'kind' parameter (matching most other uses where obj is NULL). The changes to the generated code look like: | qmp = qmp_event_build_dict("DEVICE_TRAY_MOVED"); | | qov = qmp_output_visitor_new(); |- g_assert(qov); |- | v = qmp_output_get_visitor(qov); |- g_assert(v); | |- /* Fake visit, as if all members are under a structure */ |- visit_start_struct(v, NULL, "", "DEVICE_TRAY_MOVED", 0, &err); |+ visit_start_struct(v, NULL, NULL, "DEVICE_TRAY_MOVED", 0, &err); | if (err) { | goto out; | } | visit_type_str(v, (char **)&device, "device", &err); | if (err) { |- goto out; |+ goto out_obj; | } | visit_type_bool(v, &tray_open, "tray-open", &err); | if (err) { |- goto out; |+ goto out_obj; | } |- visit_end_struct(v, &err); |+out_obj: |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } | | obj = qmp_output_get_qobject(qov); |- g_assert(obj != NULL); |+ g_assert(obj); | | qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_DEVICE_TRAY_MOVED, qmp, &err); Note that the 'goto out_obj' with no intervening code before the label, as well as the construct of 'err ? NULL : &err', are both a bit unusual but also temporary; they get fixed in a later patch that splits visit_end_struct() to drop its errp parameter by moving some checking before the label. But until that time, this was the simplest way to avoid the appearance of passing a possibly-set error to visit_end_struct(), even though actual code inspection shows that visit_end_struct() for a QMP output visitor will never set an error. Backports commit a16e3e5c5825c90887a863513916f93eeec16c55 from qemu
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g_assert(obj);
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qdict_put_obj(qmp, "data", obj);
''')
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ret += mcgen('''
emit(%(c_enum)s, qmp, &err);
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''',
c_enum=c_enum_const(event_enum_name, name))
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if arg_type and arg_type.members:
ret += mcgen('''
out:
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qmp_output_visitor_cleanup(qov);
''')
ret += mcgen('''
error_propagate(errp, err);
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QDECREF(qmp);
}
''')
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return ret
class QAPISchemaGenEventVisitor(QAPISchemaVisitor):
def __init__(self):
self.decl = None
self.defn = None
self._event_names = None
def visit_begin(self, schema):
self.decl = ''
self.defn = ''
self._event_names = []
def visit_end(self):
self.decl += gen_enum(event_enum_name, self._event_names)
self.defn += gen_enum_lookup(event_enum_name, self._event_names)
self._event_names = None;
def visit_event(self, name, info, arg_type):
self.decl += gen_event_send_decl(name, arg_type)
self.defn += gen_event_send(name, arg_type)
self._event_names.append(name)
(input_file, output_dir, do_c, do_h, prefix, dummy) = parse_command_line()
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c_comment = '''
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/*
* schema-defined QAPI event functions
*
* Copyright (c) 2014 Wenchao Xia
*
* Authors:
* Wenchao Xia <wenchaoqemu@gmail.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
'''
h_comment = '''
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/*
* schema-defined QAPI event functions
*
* Copyright (c) 2014 Wenchao Xia
*
* Authors:
* Wenchao Xia <wenchaoqemu@gmail.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
'''
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(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
'qapi-event.c', 'qapi-event.h',
c_comment, h_comment)
fdef.write(mcgen('''
#include "qemu-common.h"
#include "%(prefix)sqapi-event.h"
#include "%(prefix)sqapi-visit.h"
#include "qapi/qmp-output-visitor.h"
#include "qapi/qmp-event.h"
''',
prefix=prefix))
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fdecl.write(mcgen('''
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#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "%(prefix)sqapi-types.h"
''',
prefix=prefix))
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event_enum_name = c_name(prefix + "QAPIEvent", protect=False)
schema = QAPISchema(input_file)
gen = QAPISchemaGenEventVisitor()
schema.visit(gen)
fdef.write(gen.defn)
fdecl.write(gen.decl)
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close_output(fdef, fdecl)