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unicorn/qemu/scripts/qapi-visit.py
Eric Blake d777876e6b
qapi: Emit implicit structs in generated C 
We already have several places that want to visit all the members
of an implicit object within a larger context (simple union variant,
event with anonymous data, command with anonymous arguments struct);
and will be adding another one soon (the ability to declare an
anonymous base for a flat union). Having a C struct declared for
these implicit types, along with a visit_type_FOO_members() helper
function, will make for fewer special cases in our generator.

We do not, however, need qapi_free_FOO() or visit_type_FOO()
functions for implicit types, because they should not be used
directly outside of the generated code. This is done by adding a
conditional in visit_object_type() for both qapi-types.py and
qapi-visit.py based on the object name. The comparison of
"name.startswith('q_')" is a bit hacky (it's basically duplicating
what .is_implicit() already uses), but beats changing the signature
of the visit_object_type() callback to pass a new 'implicit' flag.
The hack should be temporary: we are considering adding a future
patch that consolidates the narrow visit_object_type(..., base,
local_members, variants) and visit_object_type_flat(...,
all_members, variants) [where different sets of information are
already broken out, and the QAPISchemaObjectType is no longer
available] into a broader visit_object_type(obj_type) [where the
visitor can query the needed fields from obj_type directly].

Also, now that we WANT to output C code for implicits, we no longer
need the visit_needed() filter, leaving 'q_empty' as the only object
still needing a special case. Remember, 'q_empty' is the only
built-in generated object, which means that without a special case
it would be emitted in multiple files (the main qapi-types.h and in
qga-qapi-types.h) causing compilation failure due to redefinition.
But since it has no members, it's easier to just avoid an attempt to
visit that particular type; since gen_object() is called recursively,
we also prime the objects_seen set to cover any recursion into the
empty type.

The patch relies on the changed naming of implicit types in the
previous patch. It is a bit unfortunate that the generated struct
names and visit_type_FOO_members() don't match normal naming
conventions, but it's not too bad, since they will only be used in
generated code.

The generated code grows substantially in size: the implicit
'-wrapper' types must be emitted in qapi-types.h before any union
can include an unboxed member of that type. Arguably, the '-args'
types could be emitted in a private header for just qapi-visit.c
and qmp-marshal.c, rather than polluting qapi-types.h; but adding
complexity to the generator to split the output location according
to role doesn't seem worth the maintenance costs.

Backports commit 7ce106a96feee4d46bfcdb47127b0935804c9357 from qemu
2018-02-21 22:31:15 -05:00

382 lines
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#
# QAPI visitor 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_visit_decl(name, scalar=False):
c_type = c_name(name) + ' *'
if not scalar:
c_type += '*'
return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error **errp);
''',
c_name=c_name(name), c_type=c_type)
def gen_visit_members_decl(name):
return mcgen('''
void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp);
''',
c_name=c_name(name))
def gen_visit_object_members(name, base, members, variants):
ret = mcgen('''
void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
{
Error *err = NULL;
''',
c_name=c_name(name))
if base:
ret += mcgen('''
visit_type_%(c_type)s_members(v, (%(c_type)s *)obj, &err);
''',
c_type=base.c_name())
ret += gen_err_check()
ret += gen_visit_members(members, prefix='obj->')
if variants:
ret += mcgen('''
switch (obj->%(c_name)s) {
''',
c_name=c_name(variants.tag_member.name))
for var in variants.variants:
# TODO ugly special case for simple union
simple_union_type = var.simple_union_type()
ret += mcgen('''
case %(case)s:
''',
case=c_enum_const(variants.tag_member.type.name,
var.name,
variants.tag_member.type.prefix))
if simple_union_type:
ret += mcgen('''
visit_type_%(c_type)s(v, "data", &obj->u.%(c_name)s, &err);
''',
c_type=simple_union_type.c_name(),
c_name=c_name(var.name))
else:
ret += mcgen('''
visit_type_%(c_type)s_members(v, &obj->u.%(c_name)s, &err);
''',
c_type=var.type.c_name(),
c_name=c_name(var.name))
ret += mcgen('''
break;
''')
ret += mcgen('''
default:
abort();
}
''')
# 'goto out' produced for base, by gen_visit_members() for each member,
# and if variants were present
if base or members or variants:
ret += mcgen('''
out:
''')
ret += mcgen('''
error_propagate(errp, err);
}
''')
return ret
def gen_visit_list(name, element_type):
# FIXME: if *obj is NULL on entry, and the first visit_next_list()
# assigns to *obj, while a later one fails, we should clean up *obj
# rather than leaving it non-NULL. As currently written, the caller must
# call qapi_free_FOOList() to avoid a memory leak of the partial FOOList.
return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
{
Error *err = NULL;
GenericList *i, **prev;
visit_start_list(v, name, &err);
if (err) {
goto out;
}
for (prev = (GenericList **)obj;
!err && (i = visit_next_list(v, prev)) != NULL;
prev = &i) {
%(c_name)s *native_i = (%(c_name)s *)i;
visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
}
error_propagate(errp, err);
err = NULL;
visit_end_list(v);
out:
error_propagate(errp, err);
}
''',
c_name=c_name(name), c_elt_type=element_type.c_name())
def gen_visit_enum(name):
return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s *obj, Error **errp)
{
int value = *obj;
visit_type_enum(v, name, &value, %(c_name)s_lookup, errp);
*obj = value;
}
''',
c_name=c_name(name))
def gen_visit_alternate(name, variants):
ret = ''
promote_int = 'true'
for var in variants.variants:
if var.type.alternate_qtype() == 'QTYPE_QINT':
promote_int = 'false'
ret += mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
{
Error *err = NULL;
visit_start_implicit_struct(v, (void**) obj, sizeof(%(c_name)s), &err);
if (err) {
goto out;
}
visit_get_next_type(v, name, &(*obj)->type, %(promote_int)s, &err);
if (err) {
goto out_obj;
}
switch ((*obj)->type) {
''',
c_name=c_name(name), promote_int=promote_int)
for var in variants.variants:
ret += mcgen('''
case %(case)s:
''',
case=var.type.alternate_qtype())
if isinstance(var.type, QAPISchemaObjectType):
ret += mcgen('''
visit_start_struct(v, name, NULL, 0, &err);
if (err) {
break;
}
visit_type_%(c_type)s_members(v, &(*obj)->u.%(c_name)s, &err);
error_propagate(errp, err);
err = NULL;
visit_end_struct(v, &err);
''',
c_type=var.type.c_name(),
c_name=c_name(var.name))
else:
ret += mcgen('''
visit_type_%(c_type)s(v, name, &(*obj)->u.%(c_name)s, &err);
''',
c_type=var.type.c_name(),
c_name=c_name(var.name))
ret += mcgen('''
break;
''')
ret += mcgen('''
default:
error_setg(&err, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
"%(name)s");
}
out_obj:
error_propagate(errp, err);
err = NULL;
visit_end_implicit_struct(v);
out:
error_propagate(errp, err);
}
''',
name=name)
return ret
def gen_visit_object(name, base, members, variants):
# FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
# *obj, but then visit_type_FOO_members() fails, we should clean up *obj
# rather than leaving it non-NULL. As currently written, the caller must
# call qapi_free_FOO() to avoid a memory leak of the partial FOO.
return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
{
Error *err = NULL;
visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
if (err) {
goto out;
}
if (!*obj) {
goto out_obj;
}
visit_type_%(c_name)s_members(v, *obj, &err);
error_propagate(errp, err);
err = NULL;
out_obj:
visit_end_struct(v, &err);
out:
error_propagate(errp, err);
}
''',
c_name=c_name(name))
class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
def __init__(self):
self.decl = None
self.defn = None
self._btin = None
def visit_begin(self, schema):
self.decl = ''
self.defn = ''
self._btin = guardstart('QAPI_VISIT_BUILTIN')
def visit_end(self):
# To avoid header dependency hell, we always generate
# declarations for built-in types in our header files and
# simply guard them. See also do_builtins (command line
# option -b).
self._btin += guardend('QAPI_VISIT_BUILTIN')
self.decl = self._btin + self.decl
self._btin = None
def visit_enum_type(self, name, info, values, prefix):
# Special case for our lone builtin enum type
# TODO use something cleaner than existence of info
if not info:
self._btin += gen_visit_decl(name, scalar=True)
if do_builtins:
self.defn += gen_visit_enum(name)
else:
self.decl += gen_visit_decl(name, scalar=True)
self.defn += gen_visit_enum(name)
def visit_array_type(self, name, info, element_type):
decl = gen_visit_decl(name)
defn = gen_visit_list(name, element_type)
if isinstance(element_type, QAPISchemaBuiltinType):
self._btin += decl
if do_builtins:
self.defn += defn
else:
self.decl += decl
self.defn += defn
def visit_object_type(self, name, info, base, members, variants):
# Nothing to do for the special empty builtin
if name == 'q_empty':
return
self.decl += gen_visit_members_decl(name)
self.decl += gen_visit_decl(name)
self.defn += gen_visit_object(name, base, members, variants)
self.defn += gen_visit_object_members(name, base, members, variants)
# TODO Worth changing the visitor signature, so we could
# directly use rather than repeat type.is_implicit()?
if not name.startswith('q_'):
# only explicit types need an allocating visit
self.decl += gen_visit_decl(name)
self.defn += gen_visit_object(name, base, members, variants)
def visit_alternate_type(self, name, info, variants):
self.decl += gen_visit_decl(name)
self.defn += gen_visit_alternate(name, variants)
# If you link code generated from multiple schemata, you want only one
# instance of the code for built-in types. Generate it only when
# do_builtins, enabled by command line option -b. See also
# QAPISchemaGenVisitVisitor.visit_end().
do_builtins = False
(input_file, output_dir, do_c, do_h, prefix, opts) = \
parse_command_line("b", ["builtins"])
for o, a in opts:
if o in ("-b", "--builtins"):
do_builtins = True
c_comment = '''
/*
* schema-defined QAPI visitor functions
*
* 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 visitor functions
*
* 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,
'qapi-visit.c', 'qapi-visit.h',
c_comment, h_comment)
fdef.write(mcgen('''
#include "qemu-common.h"
#include "%(prefix)sqapi-visit.h"
''',
prefix=prefix))
fdecl.write(mcgen('''
#include "qapi/visitor.h"
#include "qapi/qmp/qerror.h"
#include "%(prefix)sqapi-types.h"
''',
prefix=prefix))
schema = QAPISchema(input_file)
gen = QAPISchemaGenVisitVisitor()
schema.visit(gen)
fdef.write(gen.defn)
fdecl.write(gen.decl)
close_output(fdef, fdecl)
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