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"""
QOM Command abstractions.
"""
##
# Copyright John Snow 2020, for Red Hat, Inc.
# Copyright IBM, Corp. 2011
#
# Authors:
# John Snow <jsnow@redhat.com>
# Anthony Liguori <aliguori@amazon.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.
#
# Based on ./scripts/qmp/qom-[set|get|tree|list]
##
import argparse
import os
import sys
from typing import (
Any,
Dict,
List,
Optional,
Type,
TypeVar,
)
from . import QEMUMonitorProtocol, QMPError
# The following is needed only for a type alias.
Subparsers = argparse._SubParsersAction # pylint: disable=protected-access
class ObjectPropertyInfo:
"""
Represents the return type from e.g. qom-list.
"""
def __init__(self, name: str, type_: str,
description: Optional[str] = None,
default_value: Optional[object] = None):
self.name = name
self.type = type_
self.description = description
self.default_value = default_value
@classmethod
def make(cls, value: Dict[str, Any]) -> 'ObjectPropertyInfo':
"""
Build an ObjectPropertyInfo from a Dict with an unknown shape.
"""
assert value.keys() >= {'name', 'type'}
assert value.keys() <= {'name', 'type', 'description', 'default-value'}
return cls(value['name'], value['type'],
value.get('description'),
value.get('default-value'))
@property
def child(self) -> bool:
"""Is this property a child property?"""
return self.type.startswith('child<')
@property
def link(self) -> bool:
"""Is this property a link property?"""
return self.type.startswith('link<')
CommandT = TypeVar('CommandT', bound='QOMCommand')
class QOMCommand:
"""
Represents a QOM sub-command.
:param args: Parsed arguments, as returned from parser.parse_args.
"""
name: str
help: str
def __init__(self, args: argparse.Namespace):
if args.socket is None:
raise QMPError("No QMP socket path or address given")
self.qmp = QEMUMonitorProtocol(
QEMUMonitorProtocol.parse_address(args.socket)
)
self.qmp.connect()
@classmethod
def register(cls, subparsers: Subparsers) -> None:
"""
Register this command with the argument parser.
:param subparsers: argparse subparsers object, from "add_subparsers".
"""
subparser = subparsers.add_parser(cls.name, help=cls.help,
description=cls.help)
cls.configure_parser(subparser)
@classmethod
def configure_parser(cls, parser: argparse.ArgumentParser) -> None:
"""
Configure a parser with this command's arguments.
:param parser: argparse parser or subparser object.
"""
default_path = os.environ.get('QMP_SOCKET')
parser.add_argument(
'--socket', '-s',
dest='socket',
action='store',
help='QMP socket path or address (addr:port).'
' May also be set via QMP_SOCKET environment variable.',
default=default_path
)
parser.set_defaults(cmd_class=cls)
@classmethod
def add_path_prop_arg(cls, parser: argparse.ArgumentParser) -> None:
"""
Add the <path>.<proptery> positional argument to this command.
:param parser: The parser to add the argument to.
"""
parser.add_argument(
'path_prop',
metavar='<path>.<property>',
action='store',
help="QOM path and property, separated by a period '.'"
)
def run(self) -> int:
"""
Run this command.
:return: 0 on success, 1 otherwise.
"""
raise NotImplementedError
def qom_list(self, path: str) -> List[ObjectPropertyInfo]:
"""
:return: a strongly typed list from the 'qom-list' command.
"""
rsp = self.qmp.command('qom-list', path=path)
# qom-list returns List[ObjectPropertyInfo]
assert isinstance(rsp, list)
return [ObjectPropertyInfo.make(x) for x in rsp]
@classmethod
def command_runner(
cls: Type[CommandT],
args: argparse.Namespace
) -> int:
"""
Run a fully-parsed subcommand, with error-handling for the CLI.
:return: The return code from `run()`.
"""
try:
cmd = cls(args)
return cmd.run()
except QMPError as err:
print(f"{type(err).__name__}: {err!s}", file=sys.stderr)
return -1
@classmethod
def entry_point(cls) -> int:
"""
Build this command's parser, parse arguments, and run the command.
:return: `run`'s return code.
"""
parser = argparse.ArgumentParser(description=cls.help)
cls.configure_parser(parser)
args = parser.parse_args()
return cls.command_runner(args)
|
