qapi/introspect.json

# -*- Mode: Python -*-
#
# Copyright (C) 2015 Red Hat, Inc.
#
# Authors:
#  Markus Armbruster <armbru@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2 or later.
# See the COPYING file in the top-level directory.

##
# = QMP introspection
##

##
# @query-qmp-schema:
#
# Command query-qmp-schema exposes the QMP wire ABI as an array of
# SchemaInfo.  This lets QMP clients figure out what commands and
# events are available in this QEMU, and their parameters and results.
#
# However, the SchemaInfo can't reflect all the rules and restrictions
# that apply to QMP.  It's interface introspection (figuring out
# what's there), not interface specification.  The specification is in
# the QAPI schema.
#
# Furthermore, while we strive to keep the QMP wire format
# backwards-compatible across qemu versions, the introspection output
# is not guaranteed to have the same stability.  For example, one
# version of qemu may list an object member as an optional
# non-variant, while another lists the same member only through the
# object's variants; or the type of a member may change from a generic
# string into a specific enum or from one specific type into an
# alternate that includes the original type alongside something else.
#
# Returns: array of @SchemaInfo, where each element describes an
# entity in the ABI: command, event, type, ...
#
# The order of the various SchemaInfo is unspecified; however, all
# names are guaranteed to be unique (no name will be duplicated with
# different meta-types).
#
# Note: the QAPI schema is also used to help define *internal*
# interfaces, by defining QAPI types.  These are not part of the QMP
# wire ABI, and therefore not returned by this command.
#
# Since: 2.5
##
{ 'command': 'query-qmp-schema',
  'returns': [ 'SchemaInfo' ],
  'gen': false }                # just to simplify qmp_query_json()

##
# @SchemaMetaType:
#
# This is a @SchemaInfo's meta type, i.e. the kind of entity it
# describes.
#
# @builtin: a predefined type such as 'int' or 'bool'.
#
# @enum: an enumeration type
#
# @array: an array type
#
# @object: an object type (struct or union)
#
# @alternate: an alternate type
#
# @command: a QMP command
#
# @event: a QMP event
#
# Since: 2.5
##
{ 'enum': 'SchemaMetaType',
  'data': [ 'builtin', 'enum', 'array', 'object', 'alternate',
            'command', 'event' ] }

##
# @SchemaInfo:
#
# @name: the entity's name, inherited from @base.
#        The SchemaInfo is always referenced by this name.
#        Commands and events have the name defined in the QAPI schema.
#        Unlike command and event names, type names are not part of
#        the wire ABI.  Consequently, type names are meaningless
#        strings here, although they are still guaranteed unique
#        regardless of @meta-type.
#
# @meta-type: the entity's meta type, inherited from @base.
#
# Additional members depend on the value of @meta-type.
#
# Since: 2.5
##
{ 'union': 'SchemaInfo',
  'base': { 'name': 'str', 'meta-type': 'SchemaMetaType' },
  'discriminator': 'meta-type',
  'data': {
      'builtin': 'SchemaInfoBuiltin',
      'enum': 'SchemaInfoEnum',
      'array': 'SchemaInfoArray',
      'object': 'SchemaInfoObject',
      'alternate': 'SchemaInfoAlternate',
      'command': 'SchemaInfoCommand',
      'event': 'SchemaInfoEvent' } }

##
# @SchemaInfoBuiltin:
#
# Additional SchemaInfo members for meta-type 'builtin'.
#
# @json-type: the JSON type used for this type on the wire.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoBuiltin',
  'data': { 'json-type': 'JSONType' } }

##
# @JSONType:
#
# The four primitive and two structured types according to RFC 7159
# section 1, plus 'int' (split off 'number'), plus the obvious top
# type 'value'.
#
# Since: 2.5
##
{ 'enum': 'JSONType',
  'data': [ 'string', 'number', 'int', 'boolean', 'null',
            'object', 'array', 'value' ] }

##
# @SchemaInfoEnum:
#
# Additional SchemaInfo members for meta-type 'enum'.
#
# @values: the enumeration type's values, in no particular order.
#
# Values of this type are JSON string on the wire.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoEnum',
  'data': { 'values': ['str'] } }

##
# @SchemaInfoArray:
#
# Additional SchemaInfo members for meta-type 'array'.
#
# @element-type: the array type's element type.
#
# Values of this type are JSON array on the wire.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoArray',
  'data': { 'element-type': 'str' } }

##
# @SchemaInfoObject:
#
# Additional SchemaInfo members for meta-type 'object'.
#
# @members: the object type's (non-variant) members, in no particular order.
#
# @tag: the name of the member serving as type tag.
#       An element of @members with this name must exist.
#
# @variants: variant members, i.e. additional members that
#            depend on the type tag's value.  Present exactly when
#            @tag is present.  The variants are in no particular order,
#            and may even differ from the order of the values of the
#            enum type of the @tag.
#
# Values of this type are JSON object on the wire.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoObject',
  'data': { 'members': [ 'SchemaInfoObjectMember' ],
            '*tag': 'str',
            '*variants': [ 'SchemaInfoObjectVariant' ] } }

##
# @SchemaInfoObjectMember:
#
# An object member.
#
# @name: the member's name, as defined in the QAPI schema.
#
# @type: the name of the member's type.
#
# @default: default when used as command parameter.
#           If absent, the parameter is mandatory.
#           If present, the value must be null.  The parameter is
#           optional, and behavior when it's missing is not specified
#           here.
#           Future extension: if present and non-null, the parameter
#           is optional, and defaults to this value.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoObjectMember',
  'data': { 'name': 'str', 'type': 'str', '*default': 'any' } }
# @default's type must be null or match @type

##
# @SchemaInfoObjectVariant:
#
# The variant members for a value of the type tag.
#
# @case: a value of the type tag.
#
# @type: the name of the object type that provides the variant members
#        when the type tag has value @case.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoObjectVariant',
  'data': { 'case': 'str', 'type': 'str' } }

##
# @SchemaInfoAlternate:
#
# Additional SchemaInfo members for meta-type 'alternate'.
#
# @members: the alternate type's members, in no particular order.
#           The members' wire encoding is distinct, see
#           docs/devel/qapi-code-gen.txt section Alternate types.
#
# On the wire, this can be any of the members.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoAlternate',
  'data': { 'members': [ 'SchemaInfoAlternateMember' ] } }

##
# @SchemaInfoAlternateMember:
#
# An alternate member.
#
# @type: the name of the member's type.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoAlternateMember',
  'data': { 'type': 'str' } }

##
# @SchemaInfoCommand:
#
# Additional SchemaInfo members for meta-type 'command'.
#
# @arg-type: the name of the object type that provides the command's
#            parameters.
#
# @ret-type: the name of the command's result type.
#
# TODO: @success-response (currently irrelevant, because it's QGA, not QMP)
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoCommand',
  'data': { 'arg-type': 'str', 'ret-type': 'str' } }

##
# @SchemaInfoEvent:
#
# Additional SchemaInfo members for meta-type 'event'.
#
# @arg-type: the name of the object type that provides the event's
#            parameters.
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoEvent',
  'data': { 'arg-type': 'str' } }