xref: /qemu/scripts/qapi/introspect.py (revision d7a84021) 
1"""
2QAPI introspection generator
3
4Copyright (C) 2015-2021 Red Hat, Inc.
5
6Authors:
7 Markus Armbruster <armbru@redhat.com>
8 John Snow <jsnow@redhat.com>
9
10This work is licensed under the terms of the GNU GPL, version 2.
11See the COPYING file in the top-level directory.
12"""
13
14from typing import (
15    Any,
16    Dict,
17    Generic,
18    Iterable,
19    List,
20    Optional,
21    Sequence,
22    Tuple,
23    TypeVar,
24    Union,
25)
26
27from .common import (
28    c_name,
29    gen_endif,
30    gen_if,
31    mcgen,
32)
33from .gen import QAPISchemaMonolithicCVisitor
34from .schema import (
35    QAPISchema,
36    QAPISchemaArrayType,
37    QAPISchemaBuiltinType,
38    QAPISchemaEntity,
39    QAPISchemaEnumMember,
40    QAPISchemaFeature,
41    QAPISchemaObjectType,
42    QAPISchemaObjectTypeMember,
43    QAPISchemaType,
44    QAPISchemaVariant,
45    QAPISchemaVariants,
46)
47from .source import QAPISourceInfo
48
49
50# This module constructs a tree data structure that is used to
51# generate the introspection information for QEMU. It is shaped
52# like a JSON value.
53#
54# A complexity over JSON is that our values may or may not be annotated.
55#
56# Un-annotated values may be:
57#     Scalar: str, bool, None.
58#     Non-scalar: List, Dict
59# _value = Union[str, bool, None, Dict[str, JSONValue], List[JSONValue]]
60#
61# With optional annotations, the type of all values is:
62# JSONValue = Union[_Value, Annotated[_Value]]
63#
64# Sadly, mypy does not support recursive types; so the _Stub alias is used to
65# mark the imprecision in the type model where we'd otherwise use JSONValue.
66_Stub = Any
67_Scalar = Union[str, bool, None]
68_NonScalar = Union[Dict[str, _Stub], List[_Stub]]
69_Value = Union[_Scalar, _NonScalar]
70JSONValue = Union[_Value, 'Annotated[_Value]']
71
72# These types are based on structures defined in QEMU's schema, so we
73# lack precise types for them here. Python 3.6 does not offer
74# TypedDict constructs, so they are broadly typed here as simple
75# Python Dicts.
76SchemaInfo = Dict[str, object]
77SchemaInfoObject = Dict[str, object]
78SchemaInfoObjectVariant = Dict[str, object]
79SchemaInfoObjectMember = Dict[str, object]
80SchemaInfoCommand = Dict[str, object]
81
82
83_ValueT = TypeVar('_ValueT', bound=_Value)
84
85
86class Annotated(Generic[_ValueT]):
87    """
88    Annotated generally contains a SchemaInfo-like type (as a dict),
89    But it also used to wrap comments/ifconds around scalar leaf values,
90    for the benefit of features and enums.
91    """
92    # TODO: Remove after Python 3.7 adds @dataclass:
93    # pylint: disable=too-few-public-methods
94    def __init__(self, value: _ValueT, ifcond: Iterable[str],
95                 comment: Optional[str] = None):
96        self.value = value
97        self.comment: Optional[str] = comment
98        self.ifcond: Tuple[str, ...] = tuple(ifcond)
99
100
101def _tree_to_qlit(obj: JSONValue,
102                  level: int = 0,
103                  dict_value: bool = False) -> str:
104    """
105    Convert the type tree into a QLIT C string, recursively.
106
107    :param obj: The value to convert.
108                This value may not be Annotated when dict_value is True.
109    :param level: The indentation level for this particular value.
110    :param dict_value: True when the value being processed belongs to a
111                       dict key; which suppresses the output indent.
112    """
113
114    def indent(level: int) -> str:
115        return level * 4 * ' '
116
117    if isinstance(obj, Annotated):
118        # NB: _tree_to_qlit is called recursively on the values of a
119        # key:value pair; those values can't be decorated with
120        # comments or conditionals.
121        msg = "dict values cannot have attached comments or if-conditionals."
122        assert not dict_value, msg
123
124        ret = ''
125        if obj.comment:
126            ret += indent(level) + f"/* {obj.comment} */\n"
127        if obj.ifcond:
128            ret += gen_if(obj.ifcond)
129        ret += _tree_to_qlit(obj.value, level)
130        if obj.ifcond:
131            ret += '\n' + gen_endif(obj.ifcond)
132        return ret
133
134    ret = ''
135    if not dict_value:
136        ret += indent(level)
137
138    # Scalars:
139    if obj is None:
140        ret += 'QLIT_QNULL'
141    elif isinstance(obj, str):
142        ret += f"QLIT_QSTR({to_c_string(obj)})"
143    elif isinstance(obj, bool):
144        ret += f"QLIT_QBOOL({str(obj).lower()})"
145
146    # Non-scalars:
147    elif isinstance(obj, list):
148        ret += 'QLIT_QLIST(((QLitObject[]) {\n'
149        for value in obj:
150            ret += _tree_to_qlit(value, level + 1).strip('\n') + '\n'
151        ret += indent(level + 1) + '{}\n'
152        ret += indent(level) + '}))'
153    elif isinstance(obj, dict):
154        ret += 'QLIT_QDICT(((QLitDictEntry[]) {\n'
155        for key, value in sorted(obj.items()):
156            ret += indent(level + 1) + "{{ {:s}, {:s} }},\n".format(
157                to_c_string(key),
158                _tree_to_qlit(value, level + 1, dict_value=True)
159            )
160        ret += indent(level + 1) + '{}\n'
161        ret += indent(level) + '}))'
162    else:
163        raise NotImplementedError(
164            f"type '{type(obj).__name__}' not implemented"
165        )
166
167    if level > 0:
168        ret += ','
169    return ret
170
171
172def to_c_string(string: str) -> str:
173    return '"' + string.replace('\\', r'\\').replace('"', r'\"') + '"'
174
175
176class QAPISchemaGenIntrospectVisitor(QAPISchemaMonolithicCVisitor):
177
178    def __init__(self, prefix: str, unmask: bool):
179        super().__init__(
180            prefix, 'qapi-introspect',
181            ' * QAPI/QMP schema introspection', __doc__)
182        self._unmask = unmask
183        self._schema: Optional[QAPISchema] = None
184        self._trees: List[Annotated[SchemaInfo]] = []
185        self._used_types: List[QAPISchemaType] = []
186        self._name_map: Dict[str, str] = {}
187        self._genc.add(mcgen('''
188#include "qemu/osdep.h"
189#include "%(prefix)sqapi-introspect.h"
190
191''',
192                             prefix=prefix))
193
194    def visit_begin(self, schema: QAPISchema) -> None:
195        self._schema = schema
196
197    def visit_end(self) -> None:
198        # visit the types that are actually used
199        for typ in self._used_types:
200            typ.visit(self)
201        # generate C
202        name = c_name(self._prefix, protect=False) + 'qmp_schema_qlit'
203        self._genh.add(mcgen('''
204#include "qapi/qmp/qlit.h"
205
206extern const QLitObject %(c_name)s;
207''',
208                             c_name=c_name(name)))
209        self._genc.add(mcgen('''
210const QLitObject %(c_name)s = %(c_string)s;
211''',
212                             c_name=c_name(name),
213                             c_string=_tree_to_qlit(self._trees)))
214        self._schema = None
215        self._trees = []
216        self._used_types = []
217        self._name_map = {}
218
219    def visit_needed(self, entity: QAPISchemaEntity) -> bool:
220        # Ignore types on first pass; visit_end() will pick up used types
221        return not isinstance(entity, QAPISchemaType)
222
223    def _name(self, name: str) -> str:
224        if self._unmask:
225            return name
226        if name not in self._name_map:
227            self._name_map[name] = '%d' % len(self._name_map)
228        return self._name_map[name]
229
230    def _use_type(self, typ: QAPISchemaType) -> str:
231        assert self._schema is not None
232
233        # Map the various integer types to plain int
234        if typ.json_type() == 'int':
235            typ = self._schema.lookup_type('int')
236        elif (isinstance(typ, QAPISchemaArrayType) and
237              typ.element_type.json_type() == 'int'):
238            typ = self._schema.lookup_type('intList')
239        # Add type to work queue if new
240        if typ not in self._used_types:
241            self._used_types.append(typ)
242        # Clients should examine commands and events, not types.  Hide
243        # type names as integers to reduce the temptation.  Also, it
244        # saves a few characters on the wire.
245        if isinstance(typ, QAPISchemaBuiltinType):
246            return typ.name
247        if isinstance(typ, QAPISchemaArrayType):
248            return '[' + self._use_type(typ.element_type) + ']'
249        return self._name(typ.name)
250
251    @staticmethod
252    def _gen_features(features: Sequence[QAPISchemaFeature]
253                      ) -> List[Annotated[str]]:
254        return [Annotated(f.name, f.ifcond) for f in features]
255
256    def _gen_tree(self, name: str, mtype: str, obj: Dict[str, object],
257                  ifcond: Sequence[str] = (),
258                  features: Sequence[QAPISchemaFeature] = ()) -> None:
259        """
260        Build and append a SchemaInfo object to self._trees.
261
262        :param name: The SchemaInfo's name.
263        :param mtype: The SchemaInfo's meta-type.
264        :param obj: Additional SchemaInfo members, as appropriate for
265                    the meta-type.
266        :param ifcond: Conditionals to apply to the SchemaInfo.
267        :param features: The SchemaInfo's features.
268                         Will be omitted from the output if empty.
269        """
270        comment: Optional[str] = None
271        if mtype not in ('command', 'event', 'builtin', 'array'):
272            if not self._unmask:
273                # Output a comment to make it easy to map masked names
274                # back to the source when reading the generated output.
275                comment = f'"{self._name(name)}" = {name}'
276            name = self._name(name)
277        obj['name'] = name
278        obj['meta-type'] = mtype
279        if features:
280            obj['features'] = self._gen_features(features)
281        self._trees.append(Annotated(obj, ifcond, comment))
282
283    def _gen_member(self, member: QAPISchemaObjectTypeMember
284                    ) -> Annotated[SchemaInfoObjectMember]:
285        obj: SchemaInfoObjectMember = {
286            'name': member.name,
287            'type': self._use_type(member.type)
288        }
289        if member.optional:
290            obj['default'] = None
291        if member.features:
292            obj['features'] = self._gen_features(member.features)
293        return Annotated(obj, member.ifcond)
294
295    def _gen_variant(self, variant: QAPISchemaVariant
296                     ) -> Annotated[SchemaInfoObjectVariant]:
297        obj: SchemaInfoObjectVariant = {
298            'case': variant.name,
299            'type': self._use_type(variant.type)
300        }
301        return Annotated(obj, variant.ifcond)
302
303    def visit_builtin_type(self, name: str, info: Optional[QAPISourceInfo],
304                           json_type: str) -> None:
305        self._gen_tree(name, 'builtin', {'json-type': json_type})
306
307    def visit_enum_type(self, name: str, info: Optional[QAPISourceInfo],
308                        ifcond: Sequence[str],
309                        features: List[QAPISchemaFeature],
310                        members: List[QAPISchemaEnumMember],
311                        prefix: Optional[str]) -> None:
312        self._gen_tree(
313            name, 'enum',
314            {'values': [Annotated(m.name, m.ifcond) for m in members]},
315            ifcond, features
316        )
317
318    def visit_array_type(self, name: str, info: Optional[QAPISourceInfo],
319                         ifcond: Sequence[str],
320                         element_type: QAPISchemaType) -> None:
321        element = self._use_type(element_type)
322        self._gen_tree('[' + element + ']', 'array', {'element-type': element},
323                       ifcond)
324
325    def visit_object_type_flat(self, name: str, info: Optional[QAPISourceInfo],
326                               ifcond: Sequence[str],
327                               features: List[QAPISchemaFeature],
328                               members: List[QAPISchemaObjectTypeMember],
329                               variants: Optional[QAPISchemaVariants]) -> None:
330        obj: SchemaInfoObject = {
331            'members': [self._gen_member(m) for m in members]
332        }
333        if variants:
334            obj['tag'] = variants.tag_member.name
335            obj['variants'] = [self._gen_variant(v) for v in variants.variants]
336        self._gen_tree(name, 'object', obj, ifcond, features)
337
338    def visit_alternate_type(self, name: str, info: Optional[QAPISourceInfo],
339                             ifcond: Sequence[str],
340                             features: List[QAPISchemaFeature],
341                             variants: QAPISchemaVariants) -> None:
342        self._gen_tree(
343            name, 'alternate',
344            {'members': [Annotated({'type': self._use_type(m.type)},
345                                   m.ifcond)
346                         for m in variants.variants]},
347            ifcond, features
348        )
349
350    def visit_command(self, name: str, info: Optional[QAPISourceInfo],
351                      ifcond: Sequence[str],
352                      features: List[QAPISchemaFeature],
353                      arg_type: Optional[QAPISchemaObjectType],
354                      ret_type: Optional[QAPISchemaType], gen: bool,
355                      success_response: bool, boxed: bool, allow_oob: bool,
356                      allow_preconfig: bool, coroutine: bool) -> None:
357        assert self._schema is not None
358
359        arg_type = arg_type or self._schema.the_empty_object_type
360        ret_type = ret_type or self._schema.the_empty_object_type
361        obj: SchemaInfoCommand = {
362            'arg-type': self._use_type(arg_type),
363            'ret-type': self._use_type(ret_type)
364        }
365        if allow_oob:
366            obj['allow-oob'] = allow_oob
367        self._gen_tree(name, 'command', obj, ifcond, features)
368
369    def visit_event(self, name: str, info: Optional[QAPISourceInfo],
370                    ifcond: Sequence[str], features: List[QAPISchemaFeature],
371                    arg_type: Optional[QAPISchemaObjectType],
372                    boxed: bool) -> None:
373        assert self._schema is not None
374
375        arg_type = arg_type or self._schema.the_empty_object_type
376        self._gen_tree(name, 'event', {'arg-type': self._use_type(arg_type)},
377                       ifcond, features)
378
379
380def gen_introspect(schema: QAPISchema, output_dir: str, prefix: str,
381                   opt_unmask: bool) -> None:
382    vis = QAPISchemaGenIntrospectVisitor(prefix, opt_unmask)
383    schema.visit(vis)
384    vis.write(output_dir)
385