scripts/qapi/expr.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 # Copyright IBM, Corp. 2011
   4 # Copyright (c) 2013-2021 Red Hat Inc.
   5 #
   6 # Authors:
   7 #  Anthony Liguori <aliguori@us.ibm.com>
   8 #  Markus Armbruster <armbru@redhat.com>
   9 #  Eric Blake <eblake@redhat.com>
  10 #  Marc-André Lureau <marcandre.lureau@redhat.com>
  11 #  John Snow <jsnow@redhat.com>
  12 #
  13 # This work is licensed under the terms of the GNU GPL, version 2.
  14 # See the COPYING file in the top-level directory.
  15
  16 """
  17 Normalize and validate (context-free) QAPI schema expression structures.
  18
  19 `QAPISchemaParser` parses a QAPI schema into abstract syntax trees
  20 consisting of dict, list, str, bool, and int nodes.  This module ensures
  21 that these nested structures have the correct type(s) and key(s) where
  22 appropriate for the QAPI context-free grammar.
  23
  24 The QAPI schema expression language allows for certain syntactic sugar;
  25 this module also handles the normalization process of these nested
  26 structures.
  27
  28 See `check_exprs` for the main entry point.
  29
  30 See `schema.QAPISchema` for processing into native Python data
  31 structures and contextual semantic validation.
  32 """
  33
  34 import re
  35 from typing import (
  36     Collection,
  37     Dict,
  38     Iterable,
  39     List,
  40     Optional,
  41     Union,
  42     cast,
  43 )
  44
  45 from .common import c_name
  46 from .error import QAPISemError
  47 from .parser import QAPIDoc
  48 from .source import QAPISourceInfo
  49
  50
  51 # Deserialized JSON objects as returned by the parser.
  52 # The values of this mapping are not necessary to exhaustively type
  53 # here (and also not practical as long as mypy lacks recursive
  54 # types), because the purpose of this module is to interrogate that
  55 # type.
  56 _JSONObject = Dict[str, object]
  57
  58
  59 # See check_name_str(), below.
  60 valid_name = re.compile(r'(__[a-z0-9.-]+_)?'
  61                         r'(x-)?'
  62                         r'([a-z][a-z0-9_-]*)$', re.IGNORECASE)
  63
  64
  65 def check_name_is_str(name: object,
  66                       info: QAPISourceInfo,
  67                       source: str) -> None:
  68     """
  69     Ensure that ``name`` is a ``str``.
  70
  71     :raise QAPISemError: When ``name`` fails validation.
  72     """
  73     if not isinstance(name, str):
  74         raise QAPISemError(info, "%s requires a string name" % source)
  75
  76
  77 def check_name_str(name: str, info: QAPISourceInfo, source: str) -> str:
  78     """
  79     Ensure that ``name`` is a valid QAPI name.
  80
  81     A valid name consists of ASCII letters, digits, ``-``, and ``_``,
  82     starting with a letter.  It may be prefixed by a downstream prefix
  83     of the form __RFQDN_, or the experimental prefix ``x-``.  If both
  84     prefixes are present, the __RFDQN_ prefix goes first.
  85
  86     A valid name cannot start with ``q_``, which is reserved.
  87
  88     :param name: Name to check.
  89     :param info: QAPI schema source file information.
  90     :param source: Error string describing what ``name`` belongs to.
  91
  92     :raise QAPISemError: When ``name`` fails validation.
  93     :return: The stem of the valid name, with no prefixes.
  94     """
  95     # Reserve the entire 'q_' namespace for c_name(), and for 'q_empty'
  96     # and 'q_obj_*' implicit type names.
  97     match = valid_name.match(name)
  98     if not match or c_name(name, False).startswith('q_'):
  99         raise QAPISemError(info, "%s has an invalid name" % source)
 100     return match.group(3)
 101
 102
 103 def check_name_upper(name: str, info: QAPISourceInfo, source: str) -> None:
 104     """
 105     Ensure that ``name`` is a valid event name.
 106
 107     This means it must be a valid QAPI name as checked by
 108     `check_name_str()`, but where the stem prohibits lowercase
 109     characters and ``-``.
 110
 111     :param name: Name to check.
 112     :param info: QAPI schema source file information.
 113     :param source: Error string describing what ``name`` belongs to.
 114
 115     :raise QAPISemError: When ``name`` fails validation.
 116     """
 117     stem = check_name_str(name, info, source)
 118     if re.search(r'[a-z-]', stem):
 119         raise QAPISemError(
 120             info, "name of %s must not use lowercase or '-'" % source)
 121
 122
 123 def check_name_lower(name: str, info: QAPISourceInfo, source: str,
 124                      permit_upper: bool = False,
 125                      permit_underscore: bool = False) -> None:
 126     """
 127     Ensure that ``name`` is a valid command or member name.
 128
 129     This means it must be a valid QAPI name as checked by
 130     `check_name_str()`, but where the stem prohibits uppercase
 131     characters and ``_``.
 132
 133     :param name: Name to check.
 134     :param info: QAPI schema source file information.
 135     :param source: Error string describing what ``name`` belongs to.
 136     :param permit_upper: Additionally permit uppercase.
 137     :param permit_underscore: Additionally permit ``_``.
 138
 139     :raise QAPISemError: When ``name`` fails validation.
 140     """
 141     stem = check_name_str(name, info, source)
 142     if ((not permit_upper and re.search(r'[A-Z]', stem))
 143             or (not permit_underscore and '_' in stem)):
 144         raise QAPISemError(
 145             info, "name of %s must not use uppercase or '_'" % source)
 146
 147
 148 def check_name_camel(name: str, info: QAPISourceInfo, source: str) -> None:
 149     """
 150     Ensure that ``name`` is a valid user-defined type name.
 151
 152     This means it must be a valid QAPI name as checked by
 153     `check_name_str()`, but where the stem must be in CamelCase.
 154
 155     :param name: Name to check.
 156     :param info: QAPI schema source file information.
 157     :param source: Error string describing what ``name`` belongs to.
 158
 159     :raise QAPISemError: When ``name`` fails validation.
 160     """
 161     stem = check_name_str(name, info, source)
 162     if not re.match(r'[A-Z][A-Za-z0-9]*[a-z][A-Za-z0-9]*$', stem):
 163         raise QAPISemError(info, "name of %s must use CamelCase" % source)
 164
 165
 166 def check_defn_name_str(name: str, info: QAPISourceInfo, meta: str) -> None:
 167     """
 168     Ensure that ``name`` is a valid definition name.
 169
 170     Based on the value of ``meta``, this means that:
 171       - 'event' names adhere to `check_name_upper()`.
 172       - 'command' names adhere to `check_name_lower()`.
 173       - Else, meta is a type, and must pass `check_name_camel()`.
 174         These names must not end with ``List``.
 175
 176     :param name: Name to check.
 177     :param info: QAPI schema source file information.
 178     :param meta: Meta-type name of the QAPI expression.
 179
 180     :raise QAPISemError: When ``name`` fails validation.
 181     """
 182     if meta == 'event':
 183         check_name_upper(name, info, meta)
 184     elif meta == 'command':
 185         check_name_lower(
 186             name, info, meta,
 187             permit_underscore=name in info.pragma.command_name_exceptions)
 188     else:
 189         check_name_camel(name, info, meta)
 190         if name.endswith('List'):
 191             raise QAPISemError(
 192                 info, "%s name should not end in 'List'" % meta)
 193
 194
 195 def check_keys(value: _JSONObject,
 196                info: QAPISourceInfo,
 197                source: str,
 198                required: Collection[str],
 199                optional: Collection[str]) -> None:
 200     """
 201     Ensure that a dict has a specific set of keys.
 202
 203     :param value: The dict to check.
 204     :param info: QAPI schema source file information.
 205     :param source: Error string describing this ``value``.
 206     :param required: Keys that *must* be present.
 207     :param optional: Keys that *may* be present.
 208
 209     :raise QAPISemError: When unknown keys are present.
 210     """
 211
 212     def pprint(elems: Iterable[str]) -> str:
 213         return ', '.join("'" + e + "'" for e in sorted(elems))
 214
 215     missing = set(required) - set(value)
 216     if missing:
 217         raise QAPISemError(
 218             info,
 219             "%s misses key%s %s"
 220             % (source, 's' if len(missing) > 1 else '',
 221                pprint(missing)))
 222     allowed = set(required) | set(optional)
 223     unknown = set(value) - allowed
 224     if unknown:
 225         raise QAPISemError(
 226             info,
 227             "%s has unknown key%s %s\nValid keys are %s."
 228             % (source, 's' if len(unknown) > 1 else '',
 229                pprint(unknown), pprint(allowed)))
 230
 231
 232 def check_flags(expr: _JSONObject, info: QAPISourceInfo) -> None:
 233     """
 234     Ensure flag members (if present) have valid values.
 235
 236     :param expr: The expression to validate.
 237     :param info: QAPI schema source file information.
 238
 239     :raise QAPISemError:
 240         When certain flags have an invalid value, or when
 241         incompatible flags are present.
 242     """
 243     for key in ('gen', 'success-response'):
 244         if key in expr and expr[key] is not False:
 245             raise QAPISemError(
 246                 info, "flag '%s' may only use false value" % key)
 247     for key in ('boxed', 'allow-oob', 'allow-preconfig', 'coroutine'):
 248         if key in expr and expr[key] is not True:
 249             raise QAPISemError(
 250                 info, "flag '%s' may only use true value" % key)
 251     if 'allow-oob' in expr and 'coroutine' in expr:
 252         # This is not necessarily a fundamental incompatibility, but
 253         # we don't have a use case and the desired semantics isn't
 254         # obvious.  The simplest solution is to forbid it until we get
 255         # a use case for it.
 256         raise QAPISemError(info, "flags 'allow-oob' and 'coroutine' "
 257                                  "are incompatible")
 258
 259
 260 def check_if(expr: _JSONObject, info: QAPISourceInfo, source: str) -> None:
 261     """
 262     Validate the ``if`` member of an object.
 263
 264     The ``if`` member may be either a ``str`` or a dict.
 265
 266     :param expr: The expression containing the ``if`` member to validate.
 267     :param info: QAPI schema source file information.
 268     :param source: Error string describing ``expr``.
 269
 270     :raise QAPISemError:
 271         When the "if" member fails validation, or when there are no
 272         non-empty conditions.
 273     :return: None
 274     """
 275
 276     def _check_if(cond: Union[str, object]) -> None:
 277         if isinstance(cond, str):
 278             if not re.fullmatch(r'[A-Z][A-Z0-9_]*', cond):
 279                 raise QAPISemError(
 280                     info,
 281                     "'if' condition '%s' of %s is not a valid identifier"
 282                     % (cond, source))
 283             return
 284
 285         if not isinstance(cond, dict):
 286             raise QAPISemError(
 287                 info,
 288                 "'if' condition of %s must be a string or an object" % source)
 289         check_keys(cond, info, "'if' condition of %s" % source, [],
 290                    ["all", "any", "not"])
 291         if len(cond) != 1:
 292             raise QAPISemError(
 293                 info,
 294                 "'if' condition of %s has conflicting keys" % source)
 295
 296         if 'not' in cond:
 297             _check_if(cond['not'])
 298         elif 'all' in cond:
 299             _check_infix('all', cond['all'])
 300         else:
 301             _check_infix('any', cond['any'])
 302
 303     def _check_infix(operator: str, operands: object) -> None:
 304         if not isinstance(operands, list):
 305             raise QAPISemError(
 306                 info,
 307                 "'%s' condition of %s must be an array"
 308                 % (operator, source))
 309         if not operands:
 310             raise QAPISemError(
 311                 info, "'if' condition [] of %s is useless" % source)
 312         for operand in operands:
 313             _check_if(operand)
 314
 315     ifcond = expr.get('if')
 316     if ifcond is None:
 317         return
 318
 319     _check_if(ifcond)
 320
 321
 322 def normalize_members(members: object) -> None:
 323     """
 324     Normalize a "members" value.
 325
 326     If ``members`` is a dict, for every value in that dict, if that
 327     value is not itself already a dict, normalize it to
 328     ``{'type': value}``.
 329
 330     :forms:
 331       :sugared: ``Dict[str, Union[str, TypeRef]]``
 332       :canonical: ``Dict[str, TypeRef]``
 333
 334     :param members: The members value to normalize.
 335
 336     :return: None, ``members`` is normalized in-place as needed.
 337     """
 338     if isinstance(members, dict):
 339         for key, arg in members.items():
 340             if isinstance(arg, dict):
 341                 continue
 342             members[key] = {'type': arg}
 343
 344
 345 def check_type(value: Optional[object],
 346                info: QAPISourceInfo,
 347                source: str,
 348                allow_array: bool = False,
 349                allow_dict: Union[bool, str] = False) -> None:
 350     """
 351     Normalize and validate the QAPI type of ``value``.
 352
 353     Python types of ``str`` or ``None`` are always allowed.
 354
 355     :param value: The value to check.
 356     :param info: QAPI schema source file information.
 357     :param source: Error string describing this ``value``.
 358     :param allow_array:
 359         Allow a ``List[str]`` of length 1, which indicates an array of
 360         the type named by the list element.
 361     :param allow_dict:
 362         Allow a dict.  Its members can be struct type members or union
 363         branches.  When the value of ``allow_dict`` is in pragma
 364         ``member-name-exceptions``, the dict's keys may violate the
 365         member naming rules.  The dict members are normalized in place.
 366
 367     :raise QAPISemError: When ``value`` fails validation.
 368     :return: None, ``value`` is normalized in-place as needed.
 369     """
 370     if value is None:
 371         return
 372
 373     # Type name
 374     if isinstance(value, str):
 375         return
 376
 377     # Array type
 378     if isinstance(value, list):
 379         if not allow_array:
 380             raise QAPISemError(info, "%s cannot be an array" % source)
 381         if len(value) != 1 or not isinstance(value[0], str):
 382             raise QAPISemError(info,
 383                                "%s: array type must contain single type name" %
 384                                source)
 385         return
 386
 387     # Anonymous type
 388
 389     if not allow_dict:
 390         raise QAPISemError(info, "%s should be a type name" % source)
 391
 392     if not isinstance(value, dict):
 393         raise QAPISemError(info,
 394                            "%s should be an object or type name" % source)
 395
 396     permissive = False
 397     if isinstance(allow_dict, str):
 398         permissive = allow_dict in info.pragma.member_name_exceptions
 399
 400     # value is a dictionary, check that each member is okay
 401     for (key, arg) in value.items():
 402         key_source = "%s member '%s'" % (source, key)
 403         if key.startswith('*'):
 404             key = key[1:]
 405         check_name_lower(key, info, key_source,
 406                          permit_upper=permissive,
 407                          permit_underscore=permissive)
 408         if c_name(key, False) == 'u' or c_name(key, False).startswith('has_'):
 409             raise QAPISemError(info, "%s uses reserved name" % key_source)
 410         check_keys(arg, info, key_source, ['type'], ['if', 'features'])
 411         check_if(arg, info, key_source)
 412         check_features(arg.get('features'), info)
 413         check_type(arg['type'], info, key_source, allow_array=True)
 414
 415
 416 def check_features(features: Optional[object],
 417                    info: QAPISourceInfo) -> None:
 418     """
 419     Normalize and validate the ``features`` member.
 420
 421     ``features`` may be a ``list`` of either ``str`` or ``dict``.
 422     Any ``str`` element will be normalized to ``{'name': element}``.
 423
 424     :forms:
 425       :sugared: ``List[Union[str, Feature]]``
 426       :canonical: ``List[Feature]``
 427
 428     :param features: The features member value to validate.
 429     :param info: QAPI schema source file information.
 430
 431     :raise QAPISemError: When ``features`` fails validation.
 432     :return: None, ``features`` is normalized in-place as needed.
 433     """
 434     if features is None:
 435         return
 436     if not isinstance(features, list):
 437         raise QAPISemError(info, "'features' must be an array")
 438     features[:] = [f if isinstance(f, dict) else {'name': f}
 439                    for f in features]
 440     for feat in features:
 441         source = "'features' member"
 442         assert isinstance(feat, dict)
 443         check_keys(feat, info, source, ['name'], ['if'])
 444         check_name_is_str(feat['name'], info, source)
 445         source = "%s '%s'" % (source, feat['name'])
 446         check_name_str(feat['name'], info, source)
 447         check_if(feat, info, source)
 448
 449
 450 def check_enum(expr: _JSONObject, info: QAPISourceInfo) -> None:
 451     """
 452     Normalize and validate this expression as an ``enum`` definition.
 453
 454     :param expr: The expression to validate.
 455     :param info: QAPI schema source file information.
 456
 457     :raise QAPISemError: When ``expr`` is not a valid ``enum``.
 458     :return: None, ``expr`` is normalized in-place as needed.
 459     """
 460     name = expr['enum']
 461     members = expr['data']
 462     prefix = expr.get('prefix')
 463
 464     if not isinstance(members, list):
 465         raise QAPISemError(info, "'data' must be an array")
 466     if prefix is not None and not isinstance(prefix, str):
 467         raise QAPISemError(info, "'prefix' must be a string")
 468
 469     permissive = name in info.pragma.member_name_exceptions
 470
 471     members[:] = [m if isinstance(m, dict) else {'name': m}
 472                   for m in members]
 473     for member in members:
 474         source = "'data' member"
 475         check_keys(member, info, source, ['name'], ['if', 'features'])
 476         member_name = member['name']
 477         check_name_is_str(member_name, info, source)
 478         source = "%s '%s'" % (source, member_name)
 479         # Enum members may start with a digit
 480         if member_name[0].isdigit():
 481             member_name = 'd' + member_name  # Hack: hide the digit
 482         check_name_lower(member_name, info, source,
 483                          permit_upper=permissive,
 484                          permit_underscore=permissive)
 485         check_if(member, info, source)
 486         check_features(member.get('features'), info)
 487
 488
 489 def check_struct(expr: _JSONObject, info: QAPISourceInfo) -> None:
 490     """
 491     Normalize and validate this expression as a ``struct`` definition.
 492
 493     :param expr: The expression to validate.
 494     :param info: QAPI schema source file information.
 495
 496     :raise QAPISemError: When ``expr`` is not a valid ``struct``.
 497     :return: None, ``expr`` is normalized in-place as needed.
 498     """
 499     name = cast(str, expr['struct'])  # Checked in check_exprs
 500     members = expr['data']
 501
 502     check_type(members, info, "'data'", allow_dict=name)
 503     check_type(expr.get('base'), info, "'base'")
 504
 505
 506 def check_union(expr: _JSONObject, info: QAPISourceInfo) -> None:
 507     """
 508     Normalize and validate this expression as a ``union`` definition.
 509
 510     :param expr: The expression to validate.
 511     :param info: QAPI schema source file information.
 512
 513     :raise QAPISemError: when ``expr`` is not a valid ``union``.
 514     :return: None, ``expr`` is normalized in-place as needed.
 515     """
 516     name = cast(str, expr['union'])  # Checked in check_exprs
 517     base = expr['base']
 518     discriminator = expr['discriminator']
 519     members = expr['data']
 520
 521     check_type(base, info, "'base'", allow_dict=name)
 522     check_name_is_str(discriminator, info, "'discriminator'")
 523
 524     if not isinstance(members, dict):
 525         raise QAPISemError(info, "'data' must be an object")
 526
 527     for (key, value) in members.items():
 528         source = "'data' member '%s'" % key
 529         check_keys(value, info, source, ['type'], ['if'])
 530         check_if(value, info, source)
 531         check_type(value['type'], info, source, allow_array=not base)
 532
 533
 534 def check_alternate(expr: _JSONObject, info: QAPISourceInfo) -> None:
 535     """
 536     Normalize and validate this expression as an ``alternate`` definition.
 537
 538     :param expr: The expression to validate.
 539     :param info: QAPI schema source file information.
 540
 541     :raise QAPISemError: When ``expr`` is not a valid ``alternate``.
 542     :return: None, ``expr`` is normalized in-place as needed.
 543     """
 544     members = expr['data']
 545
 546     if not members:
 547         raise QAPISemError(info, "'data' must not be empty")
 548
 549     if not isinstance(members, dict):
 550         raise QAPISemError(info, "'data' must be an object")
 551
 552     for (key, value) in members.items():
 553         source = "'data' member '%s'" % key
 554         check_name_lower(key, info, source)
 555         check_keys(value, info, source, ['type'], ['if'])
 556         check_if(value, info, source)
 557         check_type(value['type'], info, source)
 558
 559
 560 def check_command(expr: _JSONObject, info: QAPISourceInfo) -> None:
 561     """
 562     Normalize and validate this expression as a ``command`` definition.
 563
 564     :param expr: The expression to validate.
 565     :param info: QAPI schema source file information.
 566
 567     :raise QAPISemError: When ``expr`` is not a valid ``command``.
 568     :return: None, ``expr`` is normalized in-place as needed.
 569     """
 570     args = expr.get('data')
 571     rets = expr.get('returns')
 572     boxed = expr.get('boxed', False)
 573
 574     if boxed and args is None:
 575         raise QAPISemError(info, "'boxed': true requires 'data'")
 576     check_type(args, info, "'data'", allow_dict=not boxed)
 577     check_type(rets, info, "'returns'", allow_array=True)
 578
 579
 580 def check_event(expr: _JSONObject, info: QAPISourceInfo) -> None:
 581     """
 582     Normalize and validate this expression as an ``event`` definition.
 583
 584     :param expr: The expression to validate.
 585     :param info: QAPI schema source file information.
 586
 587     :raise QAPISemError: When ``expr`` is not a valid ``event``.
 588     :return: None, ``expr`` is normalized in-place as needed.
 589     """
 590     args = expr.get('data')
 591     boxed = expr.get('boxed', False)
 592
 593     if boxed and args is None:
 594         raise QAPISemError(info, "'boxed': true requires 'data'")
 595     check_type(args, info, "'data'", allow_dict=not boxed)
 596
 597
 598 def check_exprs(exprs: List[_JSONObject]) -> List[_JSONObject]:
 599     """
 600     Validate and normalize a list of parsed QAPI schema expressions.
 601
 602     This function accepts a list of expressions and metadata as returned
 603     by the parser.  It destructively normalizes the expressions in-place.
 604
 605     :param exprs: The list of expressions to normalize and validate.
 606
 607     :raise QAPISemError: When any expression fails validation.
 608     :return: The same list of expressions (now modified).
 609     """
 610     for expr_elem in exprs:
 611         # Expression
 612         assert isinstance(expr_elem['expr'], dict)
 613         for key in expr_elem['expr'].keys():
 614             assert isinstance(key, str)
 615         expr: _JSONObject = expr_elem['expr']
 616
 617         # QAPISourceInfo
 618         assert isinstance(expr_elem['info'], QAPISourceInfo)
 619         info: QAPISourceInfo = expr_elem['info']
 620
 621         # Optional[QAPIDoc]
 622         tmp = expr_elem.get('doc')
 623         assert tmp is None or isinstance(tmp, QAPIDoc)
 624         doc: Optional[QAPIDoc] = tmp
 625
 626         if 'include' in expr:
 627             continue
 628
 629         metas = expr.keys() & {'enum', 'struct', 'union', 'alternate',
 630                                'command', 'event'}
 631         if len(metas) != 1:
 632             raise QAPISemError(
 633                 info,
 634                 "expression must have exactly one key"
 635                 " 'enum', 'struct', 'union', 'alternate',"
 636                 " 'command', 'event'")
 637         meta = metas.pop()
 638
 639         check_name_is_str(expr[meta], info, "'%s'" % meta)
 640         name = cast(str, expr[meta])
 641         info.set_defn(meta, name)
 642         check_defn_name_str(name, info, meta)
 643
 644         if doc:
 645             if doc.symbol != name:
 646                 raise QAPISemError(
 647                     info, "documentation comment is for '%s'" % doc.symbol)
 648             doc.check_expr(expr)
 649         elif info.pragma.doc_required:
 650             raise QAPISemError(info,
 651                                "documentation comment required")
 652
 653         if meta == 'enum':
 654             check_keys(expr, info, meta,
 655                        ['enum', 'data'], ['if', 'features', 'prefix'])
 656             check_enum(expr, info)
 657         elif meta == 'union':
 658             check_keys(expr, info, meta,
 659                        ['union', 'base', 'discriminator', 'data'],
 660                        ['if', 'features'])
 661             normalize_members(expr.get('base'))
 662             normalize_members(expr['data'])
 663             check_union(expr, info)
 664         elif meta == 'alternate':
 665             check_keys(expr, info, meta,
 666                        ['alternate', 'data'], ['if', 'features'])
 667             normalize_members(expr['data'])
 668             check_alternate(expr, info)
 669         elif meta == 'struct':
 670             check_keys(expr, info, meta,
 671                        ['struct', 'data'], ['base', 'if', 'features'])
 672             normalize_members(expr['data'])
 673             check_struct(expr, info)
 674         elif meta == 'command':
 675             check_keys(expr, info, meta,
 676                        ['command'],
 677                        ['data', 'returns', 'boxed', 'if', 'features',
 678                         'gen', 'success-response', 'allow-oob',
 679                         'allow-preconfig', 'coroutine'])
 680             normalize_members(expr.get('data'))
 681             check_command(expr, info)
 682         elif meta == 'event':
 683             check_keys(expr, info, meta,
 684                        ['event'], ['data', 'boxed', 'if', 'features'])
 685             normalize_members(expr.get('data'))
 686             check_event(expr, info)
 687         else:
 688             assert False, 'unexpected meta type'
 689
 690         check_if(expr, info, meta)
 691         check_features(expr.get('features'), info)
 692         check_flags(expr, info)
 693
 694     return exprs