qemu/scripts/qapi-commands.py
Markus Armbruster 0587568780 qmp: Dumb down how we run QMP command registration
The way we get QMP commands registered is high tech:

* qapi-commands.py generates qmp_init_marshal() that does the actual work

* it also generates the magic to register it as a MODULE_INIT_QAPI
  function, so it runs when someone calls
  module_call_init(MODULE_INIT_QAPI)

* main() calls module_call_init()

QEMU needs to register a few non-qapified commands.  Same high tech
works: monitor.c has its own qmp_init_marshal() along with the magic
to make it run in module_call_init(MODULE_INIT_QAPI).

QEMU also needs to unregister commands that are not wanted in this
build's configuration (commit 5032a16).  Simple enough:
qmp_unregister_commands_hack().  The difficulty is to make it run
after the generated qmp_init_marshal().  We can't simply run it in
monitor.c's qmp_init_marshal(), because the order in which the
registered functions run is indeterminate.  So qmp_init_marshal()
registers qmp_unregister_commands_hack() separately.  Since
registering *appends* to the list of registered functions, this will
make it run after all the functions that have been registered already.

I suspect it takes a long and expensive computer science education to
not find this silly.

Dumb it down as follows:

* Drop MODULE_INIT_QAPI entirely

* Give the generated qmp_init_marshal() external linkage.

* Call it instead of module_call_init(MODULE_INIT_QAPI)

* Except in QEMU proper, call new monitor_init_qmp_commands() that in
  turn calls the generated qmp_init_marshal(), registers the
  additional commands and unregisters the unwanted ones.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1488544368-30622-5-git-send-email-armbru@redhat.com>
2017-03-05 09:02:10 +01:00

320 lines
7.2 KiB
Python

#
# QAPI command marshaller generator
#
# Copyright IBM, Corp. 2011
# Copyright (C) 2014-2016 Red Hat, Inc.
#
# Authors:
# Anthony Liguori <aliguori@us.ibm.com>
# Michael Roth <mdroth@linux.vnet.ibm.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 qapi import *
import re
def gen_command_decl(name, arg_type, boxed, ret_type):
return mcgen('''
%(c_type)s qmp_%(c_name)s(%(params)s);
''',
c_type=(ret_type and ret_type.c_type()) or 'void',
c_name=c_name(name),
params=gen_params(arg_type, boxed, 'Error **errp'))
def gen_call(name, arg_type, boxed, ret_type):
ret = ''
argstr = ''
if boxed:
assert arg_type and not arg_type.is_empty()
argstr = '&arg, '
elif arg_type:
assert not arg_type.variants
for memb in arg_type.members:
if memb.optional:
argstr += 'arg.has_%s, ' % c_name(memb.name)
argstr += 'arg.%s, ' % c_name(memb.name)
lhs = ''
if ret_type:
lhs = 'retval = '
ret = mcgen('''
%(lhs)sqmp_%(c_name)s(%(args)s&err);
''',
c_name=c_name(name), args=argstr, lhs=lhs)
if ret_type:
ret += mcgen('''
if (err) {
goto out;
}
qmp_marshal_output_%(c_name)s(retval, ret, &err);
''',
c_name=ret_type.c_name())
return ret
def gen_marshal_output(ret_type):
return mcgen('''
static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject **ret_out, Error **errp)
{
Error *err = NULL;
Visitor *v;
v = qobject_output_visitor_new(ret_out);
visit_type_%(c_name)s(v, "unused", &ret_in, &err);
if (!err) {
visit_complete(v, ret_out);
}
error_propagate(errp, err);
visit_free(v);
v = qapi_dealloc_visitor_new();
visit_type_%(c_name)s(v, "unused", &ret_in, NULL);
visit_free(v);
}
''',
c_type=ret_type.c_type(), c_name=ret_type.c_name())
def gen_marshal_proto(name):
return 'void qmp_marshal_%s(QDict *args, QObject **ret, Error **errp)' % c_name(name)
def gen_marshal_decl(name):
return mcgen('''
%(proto)s;
''',
proto=gen_marshal_proto(name))
def gen_marshal(name, arg_type, boxed, ret_type):
have_args = arg_type and not arg_type.is_empty()
ret = mcgen('''
%(proto)s
{
Error *err = NULL;
''',
proto=gen_marshal_proto(name))
if ret_type:
ret += mcgen('''
%(c_type)s retval;
''',
c_type=ret_type.c_type())
if have_args:
visit_members = ('visit_type_%s_members(v, &arg, &err);'
% arg_type.c_name())
ret += mcgen('''
Visitor *v;
%(c_name)s arg = {0};
''',
c_name=arg_type.c_name())
else:
visit_members = ''
ret += mcgen('''
Visitor *v = NULL;
if (args) {
''')
push_indent()
ret += mcgen('''
v = qobject_input_visitor_new(QOBJECT(args), true);
visit_start_struct(v, NULL, NULL, 0, &err);
if (err) {
goto out;
}
%(visit_members)s
if (!err) {
visit_check_struct(v, &err);
}
visit_end_struct(v, NULL);
if (err) {
goto out;
}
''',
visit_members=visit_members)
if not have_args:
pop_indent()
ret += mcgen('''
}
''')
ret += gen_call(name, arg_type, boxed, ret_type)
ret += mcgen('''
out:
error_propagate(errp, err);
visit_free(v);
''')
if have_args:
visit_members = ('visit_type_%s_members(v, &arg, NULL);'
% arg_type.c_name())
else:
visit_members = ''
ret += mcgen('''
if (args) {
''')
push_indent()
ret += mcgen('''
v = qapi_dealloc_visitor_new();
visit_start_struct(v, NULL, NULL, 0, NULL);
%(visit_members)s
visit_end_struct(v, NULL);
visit_free(v);
''',
visit_members=visit_members)
if not have_args:
pop_indent()
ret += mcgen('''
}
''')
ret += mcgen('''
}
''')
return ret
def gen_register_command(name, success_response):
options = 'QCO_NO_OPTIONS'
if not success_response:
options = 'QCO_NO_SUCCESS_RESP'
ret = mcgen('''
qmp_register_command("%(name)s", qmp_marshal_%(c_name)s, %(opts)s);
''',
name=name, c_name=c_name(name),
opts=options)
return ret
def gen_registry(registry):
ret = mcgen('''
void qmp_init_marshal(void)
{
''')
ret += registry
ret += mcgen('''
}
''')
return ret
class QAPISchemaGenCommandVisitor(QAPISchemaVisitor):
def __init__(self):
self.decl = None
self.defn = None
self._regy = None
self._visited_ret_types = None
def visit_begin(self, schema):
self.decl = ''
self.defn = ''
self._regy = ''
self._visited_ret_types = set()
def visit_end(self):
self.defn += gen_registry(self._regy)
self._regy = None
self._visited_ret_types = None
def visit_command(self, name, info, arg_type, ret_type,
gen, success_response, boxed):
if not gen:
return
self.decl += gen_command_decl(name, arg_type, boxed, ret_type)
if ret_type and ret_type not in self._visited_ret_types:
self._visited_ret_types.add(ret_type)
self.defn += gen_marshal_output(ret_type)
self.decl += gen_marshal_decl(name)
self.defn += gen_marshal(name, arg_type, boxed, ret_type)
self._regy += gen_register_command(name, success_response)
(input_file, output_dir, do_c, do_h, prefix, opts) = parse_command_line()
c_comment = '''
/*
* schema-defined QMP->QAPI command dispatch
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.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 = '''
/*
* schema-defined QAPI function prototypes
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.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.
*
*/
'''
(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
'qmp-marshal.c', 'qmp-commands.h',
c_comment, h_comment)
fdef.write(mcgen('''
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/module.h"
#include "qapi/qmp/types.h"
#include "qapi/qmp/dispatch.h"
#include "qapi/visitor.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi/dealloc-visitor.h"
#include "%(prefix)sqapi-types.h"
#include "%(prefix)sqapi-visit.h"
#include "%(prefix)sqmp-commands.h"
''',
prefix=prefix))
fdecl.write(mcgen('''
#include "%(prefix)sqapi-types.h"
#include "qapi/qmp/qdict.h"
#include "qapi/error.h"
void qmp_init_marshal(void);
''',
prefix=prefix))
schema = QAPISchema(input_file)
gen = QAPISchemaGenCommandVisitor()
schema.visit(gen)
fdef.write(gen.defn)
fdecl.write(gen.decl)
close_output(fdef, fdecl)