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qemu-e2k/python/qemu/machine/machine.py
John Snow a4225303a1 python/machine: permanently switch to AQMP 
Remove the QEMU_PYTHON_LEGACY_QMP environment variable, making the
switch from sync qmp to async qmp permanent. Update exceptions and
import paths as necessary.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Beraldo Leal <bleal@redhat.com>
Acked-by: Hanna Reitz <hreitz@redhat.com>
Message-id: 20220321203315.909411-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
2022-04-21 11:01:00 -04:00

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"""
QEMU machine module:
The machine module primarily provides the QEMUMachine class,
which provides facilities for managing the lifetime of a QEMU VM.
"""
# Copyright (C) 2015-2016 Red Hat Inc.
# Copyright (C) 2012 IBM Corp.
#
# Authors:
# Fam Zheng <famz@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2. See
# the COPYING file in the top-level directory.
#
# Based on qmp.py.
#
import errno
from itertools import chain
import locale
import logging
import os
import shutil
import signal
import socket
import subprocess
import tempfile
from types import TracebackType
from typing import (
Any,
BinaryIO,
Dict,
List,
Optional,
Sequence,
Tuple,
Type,
TypeVar,
)
from qemu.aqmp import SocketAddrT
from qemu.aqmp.legacy import (
QEMUMonitorProtocol,
QMPMessage,
QMPReturnValue,
)
from . import console_socket
LOG = logging.getLogger(__name__)
class QEMUMachineError(Exception):
"""
Exception called when an error in QEMUMachine happens.
"""
class QEMUMachineAddDeviceError(QEMUMachineError):
"""
Exception raised when a request to add a device can not be fulfilled
The failures are caused by limitations, lack of information or conflicting
requests on the QEMUMachine methods. This exception does not represent
failures reported by the QEMU binary itself.
"""
class VMLaunchFailure(QEMUMachineError):
"""
Exception raised when a VM launch was attempted, but failed.
"""
def __init__(self, exitcode: Optional[int],
command: str, output: Optional[str]):
super().__init__(exitcode, command, output)
self.exitcode = exitcode
self.command = command
self.output = output
def __str__(self) -> str:
ret = ''
if self.__cause__ is not None:
name = type(self.__cause__).__name__
reason = str(self.__cause__)
if reason:
ret += f"{name}: {reason}"
else:
ret += f"{name}"
ret += '\n'
if self.exitcode is not None:
ret += f"\tExit code: {self.exitcode}\n"
ret += f"\tCommand: {self.command}\n"
ret += f"\tOutput: {self.output}\n"
return ret
class AbnormalShutdown(QEMUMachineError):
"""
Exception raised when a graceful shutdown was requested, but not performed.
"""
_T = TypeVar('_T', bound='QEMUMachine')
class QEMUMachine:
"""
A QEMU VM.
Use this object as a context manager to ensure
the QEMU process terminates::
with VM(binary) as vm:
...
# vm is guaranteed to be shut down here
"""
# pylint: disable=too-many-instance-attributes, too-many-public-methods
def __init__(self,
binary: str,
args: Sequence[str] = (),
wrapper: Sequence[str] = (),
name: Optional[str] = None,
base_temp_dir: str = "/var/tmp",
monitor_address: Optional[SocketAddrT] = None,
sock_dir: Optional[str] = None,
drain_console: bool = False,
console_log: Optional[str] = None,
log_dir: Optional[str] = None,
qmp_timer: Optional[float] = None):
'''
Initialize a QEMUMachine
@param binary: path to the qemu binary
@param args: list of extra arguments
@param wrapper: list of arguments used as prefix to qemu binary
@param name: prefix for socket and log file names (default: qemu-PID)
@param base_temp_dir: default location where temp files are created
@param monitor_address: address for QMP monitor
@param sock_dir: where to create socket (defaults to base_temp_dir)
@param drain_console: (optional) True to drain console socket to buffer
@param console_log: (optional) path to console log file
@param log_dir: where to create and keep log files
@param qmp_timer: (optional) default QMP socket timeout
@note: Qemu process is not started until launch() is used.
'''
# pylint: disable=too-many-arguments
# Direct user configuration
self._binary = binary
self._args = list(args)
self._wrapper = wrapper
self._qmp_timer = qmp_timer
self._name = name or f"qemu-{os.getpid()}-{id(self):02x}"
self._temp_dir: Optional[str] = None
self._base_temp_dir = base_temp_dir
self._sock_dir = sock_dir
self._log_dir = log_dir
if monitor_address is not None:
self._monitor_address = monitor_address
else:
self._monitor_address = os.path.join(
self.sock_dir, f"{self._name}-monitor.sock"
)
self._console_log_path = console_log
if self._console_log_path:
# In order to log the console, buffering needs to be enabled.
self._drain_console = True
else:
self._drain_console = drain_console
# Runstate
self._qemu_log_path: Optional[str] = None
self._qemu_log_file: Optional[BinaryIO] = None
self._popen: Optional['subprocess.Popen[bytes]'] = None
self._events: List[QMPMessage] = []
self._iolog: Optional[str] = None
self._qmp_set = True # Enable QMP monitor by default.
self._qmp_connection: Optional[QEMUMonitorProtocol] = None
self._qemu_full_args: Tuple[str, ...] = ()
self._launched = False
self._machine: Optional[str] = None
self._console_index = 0
self._console_set = False
self._console_device_type: Optional[str] = None
self._console_address = os.path.join(
self.sock_dir, f"{self._name}-console.sock"
)
self._console_socket: Optional[socket.socket] = None
self._remove_files: List[str] = []
self._user_killed = False
self._quit_issued = False
def __enter__(self: _T) -> _T:
return self
def __exit__(self,
exc_type: Optional[Type[BaseException]],
exc_val: Optional[BaseException],
exc_tb: Optional[TracebackType]) -> None:
self.shutdown()
def add_monitor_null(self) -> None:
"""
This can be used to add an unused monitor instance.
"""
self._args.append('-monitor')
self._args.append('null')
def add_fd(self: _T, fd: int, fdset: int,
opaque: str, opts: str = '') -> _T:
"""
Pass a file descriptor to the VM
"""
options = ['fd=%d' % fd,
'set=%d' % fdset,
'opaque=%s' % opaque]
if opts:
options.append(opts)
# This did not exist before 3.4, but since then it is
# mandatory for our purpose
if hasattr(os, 'set_inheritable'):
os.set_inheritable(fd, True)
self._args.append('-add-fd')
self._args.append(','.join(options))
return self
def send_fd_scm(self, fd: Optional[int] = None,
file_path: Optional[str] = None) -> int:
"""
Send an fd or file_path to the remote via SCM_RIGHTS.
Exactly one of fd and file_path must be given. If it is
file_path, the file will be opened read-only and the new file
descriptor will be sent to the remote.
"""
if file_path is not None:
assert fd is None
with open(file_path, "rb") as passfile:
fd = passfile.fileno()
self._qmp.send_fd_scm(fd)
else:
assert fd is not None
self._qmp.send_fd_scm(fd)
return 0
@staticmethod
def _remove_if_exists(path: str) -> None:
"""
Remove file object at path if it exists
"""
try:
os.remove(path)
except OSError as exception:
if exception.errno == errno.ENOENT:
return
raise
def is_running(self) -> bool:
"""Returns true if the VM is running."""
return self._popen is not None and self._popen.poll() is None
@property
def _subp(self) -> 'subprocess.Popen[bytes]':
if self._popen is None:
raise QEMUMachineError('Subprocess pipe not present')
return self._popen
def exitcode(self) -> Optional[int]:
"""Returns the exit code if possible, or None."""
if self._popen is None:
return None
return self._popen.poll()
def get_pid(self) -> Optional[int]:
"""Returns the PID of the running process, or None."""
if not self.is_running():
return None
return self._subp.pid
def _load_io_log(self) -> None:
# Assume that the output encoding of QEMU's terminal output is
# defined by our locale. If indeterminate, allow open() to fall
# back to the platform default.
_, encoding = locale.getlocale()
if self._qemu_log_path is not None:
with open(self._qemu_log_path, "r", encoding=encoding) as iolog:
self._iolog = iolog.read()
@property
def _base_args(self) -> List[str]:
args = ['-display', 'none', '-vga', 'none']
if self._qmp_set:
if isinstance(self._monitor_address, tuple):
moncdev = "socket,id=mon,host={},port={}".format(
*self._monitor_address
)
else:
moncdev = f"socket,id=mon,path={self._monitor_address}"
args.extend(['-chardev', moncdev, '-mon',
'chardev=mon,mode=control'])
if self._machine is not None:
args.extend(['-machine', self._machine])
for _ in range(self._console_index):
args.extend(['-serial', 'null'])
if self._console_set:
chardev = ('socket,id=console,path=%s,server=on,wait=off' %
self._console_address)
args.extend(['-chardev', chardev])
if self._console_device_type is None:
args.extend(['-serial', 'chardev:console'])
else:
device = '%s,chardev=console' % self._console_device_type
args.extend(['-device', device])
return args
@property
def args(self) -> List[str]:
"""Returns the list of arguments given to the QEMU binary."""
return self._args
def _pre_launch(self) -> None:
if self._console_set:
self._remove_files.append(self._console_address)
if self._qmp_set:
if isinstance(self._monitor_address, str):
self._remove_files.append(self._monitor_address)
self._qmp_connection = QEMUMonitorProtocol(
self._monitor_address,
server=True,
nickname=self._name
)
# NOTE: Make sure any opened resources are *definitely* freed in
# _post_shutdown()!
# pylint: disable=consider-using-with
self._qemu_log_path = os.path.join(self.log_dir, self._name + ".log")
self._qemu_log_file = open(self._qemu_log_path, 'wb')
self._iolog = None
self._qemu_full_args = tuple(chain(
self._wrapper,
[self._binary],
self._base_args,
self._args
))
def _post_launch(self) -> None:
if self._qmp_connection:
self._qmp.accept(self._qmp_timer)
def _close_qemu_log_file(self) -> None:
if self._qemu_log_file is not None:
self._qemu_log_file.close()
self._qemu_log_file = None
def _post_shutdown(self) -> None:
"""
Called to cleanup the VM instance after the process has exited.
May also be called after a failed launch.
"""
try:
self._close_qmp_connection()
except Exception as err: # pylint: disable=broad-except
LOG.warning(
"Exception closing QMP connection: %s",
str(err) if str(err) else type(err).__name__
)
finally:
assert self._qmp_connection is None
self._close_qemu_log_file()
self._load_io_log()
self._qemu_log_path = None
if self._temp_dir is not None:
shutil.rmtree(self._temp_dir)
self._temp_dir = None
while len(self._remove_files) > 0:
self._remove_if_exists(self._remove_files.pop())
exitcode = self.exitcode()
if (exitcode is not None and exitcode < 0
and not (self._user_killed and exitcode == -signal.SIGKILL)):
msg = 'qemu received signal %i; command: "%s"'
if self._qemu_full_args:
command = ' '.join(self._qemu_full_args)
else:
command = ''
LOG.warning(msg, -int(exitcode), command)
self._quit_issued = False
self._user_killed = False
self._launched = False
def launch(self) -> None:
"""
Launch the VM and make sure we cleanup and expose the
command line/output in case of exception
"""
if self._launched:
raise QEMUMachineError('VM already launched')
try:
self._launch()
except BaseException as exc:
# We may have launched the process but it may
# have exited before we could connect via QMP.
# Assume the VM didn't launch or is exiting.
# If we don't wait for the process, exitcode() may still be
# 'None' by the time control is ceded back to the caller.
if self._launched:
self.wait()
else:
self._post_shutdown()
if isinstance(exc, Exception):
raise VMLaunchFailure(
exitcode=self.exitcode(),
command=' '.join(self._qemu_full_args),
output=self._iolog
) from exc
# Don't wrap 'BaseException'; doing so would downgrade
# that exception. However, we still want to clean up.
raise
def _launch(self) -> None:
"""
Launch the VM and establish a QMP connection
"""
self._pre_launch()
LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
# Cleaning up of this subprocess is guaranteed by _do_shutdown.
# pylint: disable=consider-using-with
self._popen = subprocess.Popen(self._qemu_full_args,
stdin=subprocess.DEVNULL,
stdout=self._qemu_log_file,
stderr=subprocess.STDOUT,
shell=False,
close_fds=False)
self._launched = True
self._post_launch()
def _close_qmp_connection(self) -> None:
"""
Close the underlying QMP connection, if any.
Dutifully report errors that occurred while closing, but assume
that any error encountered indicates an abnormal termination
process and not a failure to close.
"""
if self._qmp_connection is None:
return
try:
self._qmp.close()
except EOFError:
# EOF can occur as an Exception here when using the Async
# QMP backend. It indicates that the server closed the
# stream. If we successfully issued 'quit' at any point,
# then this was expected. If the remote went away without
# our permission, it's worth reporting that as an abnormal
# shutdown case.
if not (self._user_killed or self._quit_issued):
raise
finally:
self._qmp_connection = None
def _early_cleanup(self) -> None:
"""
Perform any cleanup that needs to happen before the VM exits.
This method may be called twice upon shutdown, once each by soft
and hard shutdown in failover scenarios.
"""
# If we keep the console socket open, we may deadlock waiting
# for QEMU to exit, while QEMU is waiting for the socket to
# become writeable.
if self._console_socket is not None:
self._console_socket.close()
self._console_socket = None
def _hard_shutdown(self) -> None:
"""
Perform early cleanup, kill the VM, and wait for it to terminate.
:raise subprocess.Timeout: When timeout is exceeds 60 seconds
waiting for the QEMU process to terminate.
"""
self._early_cleanup()
self._subp.kill()
self._subp.wait(timeout=60)
def _soft_shutdown(self, timeout: Optional[int]) -> None:
"""
Perform early cleanup, attempt to gracefully shut down the VM, and wait
for it to terminate.
:param timeout: Timeout in seconds for graceful shutdown.
A value of None is an infinite wait.
:raise ConnectionReset: On QMP communication errors
:raise subprocess.TimeoutExpired: When timeout is exceeded waiting for
the QEMU process to terminate.
"""
self._early_cleanup()
if self._qmp_connection:
try:
if not self._quit_issued:
# May raise ExecInterruptedError or StateError if the
# connection dies or has *already* died.
self.qmp('quit')
finally:
# Regardless, we want to quiesce the connection.
self._close_qmp_connection()
# May raise subprocess.TimeoutExpired
self._subp.wait(timeout=timeout)
def _do_shutdown(self, timeout: Optional[int]) -> None:
"""
Attempt to shutdown the VM gracefully; fallback to a hard shutdown.
:param timeout: Timeout in seconds for graceful shutdown.
A value of None is an infinite wait.
:raise AbnormalShutdown: When the VM could not be shut down gracefully.
The inner exception will likely be ConnectionReset or
subprocess.TimeoutExpired. In rare cases, non-graceful termination
may result in its own exceptions, likely subprocess.TimeoutExpired.
"""
try:
self._soft_shutdown(timeout)
except Exception as exc:
self._hard_shutdown()
raise AbnormalShutdown("Could not perform graceful shutdown") \
from exc
def shutdown(self,
hard: bool = False,
timeout: Optional[int] = 30) -> None:
"""
Terminate the VM (gracefully if possible) and perform cleanup.
Cleanup will always be performed.
If the VM has not yet been launched, or shutdown(), wait(), or kill()
have already been called, this method does nothing.
:param hard: When true, do not attempt graceful shutdown, and
suppress the SIGKILL warning log message.
:param timeout: Optional timeout in seconds for graceful shutdown.
Default 30 seconds, A `None` value is an infinite wait.
"""
if not self._launched:
return
try:
if hard:
self._user_killed = True
self._hard_shutdown()
else:
self._do_shutdown(timeout)
finally:
self._post_shutdown()
def kill(self) -> None:
"""
Terminate the VM forcefully, wait for it to exit, and perform cleanup.
"""
self.shutdown(hard=True)
def wait(self, timeout: Optional[int] = 30) -> None:
"""
Wait for the VM to power off and perform post-shutdown cleanup.
:param timeout: Optional timeout in seconds. Default 30 seconds.
A value of `None` is an infinite wait.
"""
self._quit_issued = True
self.shutdown(timeout=timeout)
def set_qmp_monitor(self, enabled: bool = True) -> None:
"""
Set the QMP monitor.
@param enabled: if False, qmp monitor options will be removed from
the base arguments of the resulting QEMU command
line. Default is True.
.. note:: Call this function before launch().
"""
self._qmp_set = enabled
@property
def _qmp(self) -> QEMUMonitorProtocol:
if self._qmp_connection is None:
raise QEMUMachineError("Attempt to access QMP with no connection")
return self._qmp_connection
@classmethod
def _qmp_args(cls, conv_keys: bool,
args: Dict[str, Any]) -> Dict[str, object]:
if conv_keys:
return {k.replace('_', '-'): v for k, v in args.items()}
return args
def qmp(self, cmd: str,
args_dict: Optional[Dict[str, object]] = None,
conv_keys: Optional[bool] = None,
**args: Any) -> QMPMessage:
"""
Invoke a QMP command and return the response dict
"""
if args_dict is not None:
assert not args
assert conv_keys is None
args = args_dict
conv_keys = False
if conv_keys is None:
conv_keys = True
qmp_args = self._qmp_args(conv_keys, args)
ret = self._qmp.cmd(cmd, args=qmp_args)
if cmd == 'quit' and 'error' not in ret and 'return' in ret:
self._quit_issued = True
return ret
def command(self, cmd: str,
conv_keys: bool = True,
**args: Any) -> QMPReturnValue:
"""
Invoke a QMP command.
On success return the response dict.
On failure raise an exception.
"""
qmp_args = self._qmp_args(conv_keys, args)
ret = self._qmp.command(cmd, **qmp_args)
if cmd == 'quit':
self._quit_issued = True
return ret
def get_qmp_event(self, wait: bool = False) -> Optional[QMPMessage]:
"""
Poll for one queued QMP events and return it
"""
if self._events:
return self._events.pop(0)
return self._qmp.pull_event(wait=wait)
def get_qmp_events(self, wait: bool = False) -> List[QMPMessage]:
"""
Poll for queued QMP events and return a list of dicts
"""
events = self._qmp.get_events(wait=wait)
events.extend(self._events)
del self._events[:]
return events
@staticmethod
def event_match(event: Any, match: Optional[Any]) -> bool:
"""
Check if an event matches optional match criteria.
The match criteria takes the form of a matching subdict. The event is
checked to be a superset of the subdict, recursively, with matching
values whenever the subdict values are not None.
This has a limitation that you cannot explicitly check for None values.
Examples, with the subdict queries on the left:
- None matches any object.
- {"foo": None} matches {"foo": {"bar": 1}}
- {"foo": None} matches {"foo": 5}
- {"foo": {"abc": None}} does not match {"foo": {"bar": 1}}
- {"foo": {"rab": 2}} matches {"foo": {"bar": 1, "rab": 2}}
"""
if match is None:
return True
try:
for key in match:
if key in event:
if not QEMUMachine.event_match(event[key], match[key]):
return False
else:
return False
return True
except TypeError:
# either match or event wasn't iterable (not a dict)
return bool(match == event)
def event_wait(self, name: str,
timeout: float = 60.0,
match: Optional[QMPMessage] = None) -> Optional[QMPMessage]:
"""
event_wait waits for and returns a named event from QMP with a timeout.
name: The event to wait for.
timeout: QEMUMonitorProtocol.pull_event timeout parameter.
match: Optional match criteria. See event_match for details.
"""
return self.events_wait([(name, match)], timeout)
def events_wait(self,
events: Sequence[Tuple[str, Any]],
timeout: float = 60.0) -> Optional[QMPMessage]:
"""
events_wait waits for and returns a single named event from QMP.
In the case of multiple qualifying events, this function returns the
first one.
:param events: A sequence of (name, match_criteria) tuples.
The match criteria are optional and may be None.
See event_match for details.
:param timeout: Optional timeout, in seconds.
See QEMUMonitorProtocol.pull_event.
:raise asyncio.TimeoutError:
If timeout was non-zero and no matching events were found.
:return: A QMP event matching the filter criteria.
If timeout was 0 and no event matched, None.
"""
def _match(event: QMPMessage) -> bool:
for name, match in events:
if event['event'] == name and self.event_match(event, match):
return True
return False
event: Optional[QMPMessage]
# Search cached events
for event in self._events:
if _match(event):
self._events.remove(event)
return event
# Poll for new events
while True:
event = self._qmp.pull_event(wait=timeout)
if event is None:
# NB: None is only returned when timeout is false-ish.
# Timeouts raise asyncio.TimeoutError instead!
break
if _match(event):
return event
self._events.append(event)
return None
def get_log(self) -> Optional[str]:
"""
After self.shutdown or failed qemu execution, this returns the output
of the qemu process.
"""
return self._iolog
def add_args(self, *args: str) -> None:
"""
Adds to the list of extra arguments to be given to the QEMU binary
"""
self._args.extend(args)
def set_machine(self, machine_type: str) -> None:
"""
Sets the machine type
If set, the machine type will be added to the base arguments
of the resulting QEMU command line.
"""
self._machine = machine_type
def set_console(self,
device_type: Optional[str] = None,
console_index: int = 0) -> None:
"""
Sets the device type for a console device
If set, the console device and a backing character device will
be added to the base arguments of the resulting QEMU command
line.
This is a convenience method that will either use the provided
device type, or default to a "-serial chardev:console" command
line argument.
The actual setting of command line arguments will be be done at
machine launch time, as it depends on the temporary directory
to be created.
@param device_type: the device type, such as "isa-serial". If
None is given (the default value) a "-serial
chardev:console" command line argument will
be used instead, resorting to the machine's
default device type.
@param console_index: the index of the console device to use.
If not zero, the command line will create
'index - 1' consoles and connect them to
the 'null' backing character device.
"""
self._console_set = True
self._console_device_type = device_type
self._console_index = console_index
@property
def console_socket(self) -> socket.socket:
"""
Returns a socket connected to the console
"""
if self._console_socket is None:
self._console_socket = console_socket.ConsoleSocket(
self._console_address,
file=self._console_log_path,
drain=self._drain_console)
return self._console_socket
@property
def temp_dir(self) -> str:
"""
Returns a temporary directory to be used for this machine
"""
if self._temp_dir is None:
self._temp_dir = tempfile.mkdtemp(prefix="qemu-machine-",
dir=self._base_temp_dir)
return self._temp_dir
@property
def sock_dir(self) -> str:
"""
Returns the directory used for sockfiles by this machine.
"""
if self._sock_dir:
return self._sock_dir
return self.temp_dir
@property
def log_dir(self) -> str:
"""
Returns a directory to be used for writing logs
"""
if self._log_dir is None:
return self.temp_dir
return self._log_dir
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