scripts/qapi/introspect.py

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