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[PATCH 05/15] python/qmp: add send_fd_scm directly to QEMUMonitorProtoco
From: |
John Snow |
Subject: |
[PATCH 05/15] python/qmp: add send_fd_scm directly to QEMUMonitorProtocol |
Date: |
Fri, 17 Sep 2021 01:40:37 -0400 |
It turns out you can do this directly from Python ... and because of
this, you don't need to worry about setting the inheritability of the
fds or spawning another process.
Doing this is helpful because it allows QEMUMonitorProtocol to keep its
file descriptor and socket object as private implementation details.
*that* is helpful in turn because it allows me to write a compatible,
alternative implementation.
Signed-off-by: John Snow <jsnow@redhat.com>
---
python/qemu/machine/machine.py | 44 +++++++---------------------------
python/qemu/qmp/__init__.py | 21 +++++++---------
2 files changed, 18 insertions(+), 47 deletions(-)
diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py
index ae945ca3c9..1c6532a3d6 100644
--- a/python/qemu/machine/machine.py
+++ b/python/qemu/machine/machine.py
@@ -213,48 +213,22 @@ def add_fd(self: _T, fd: int, fdset: int,
def send_fd_scm(self, fd: Optional[int] = None,
file_path: Optional[str] = None) -> int:
"""
- Send an fd or file_path to socket_scm_helper.
+ 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 helper will open that file and pass its own fd.
+ 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.
"""
- # In iotest.py, the qmp should always use unix socket.
- assert self._qmp.is_scm_available()
- if self._socket_scm_helper is None:
- raise QEMUMachineError("No path to socket_scm_helper set")
- if not os.path.exists(self._socket_scm_helper):
- raise QEMUMachineError("%s does not exist" %
- self._socket_scm_helper)
-
- # This did not exist before 3.4, but since then it is
- # mandatory for our purpose
- if hasattr(os, 'set_inheritable'):
- os.set_inheritable(self._qmp.get_sock_fd(), True)
- if fd is not None:
- os.set_inheritable(fd, True)
-
- fd_param = ["%s" % self._socket_scm_helper,
- "%d" % self._qmp.get_sock_fd()]
-
if file_path is not None:
assert fd is None
- fd_param.append(file_path)
+ with open(file_path, "rb") as passfile:
+ fd = passfile.fileno()
+ self._qmp.send_fd_scm(fd)
else:
assert fd is not None
- fd_param.append(str(fd))
+ self._qmp.send_fd_scm(fd)
- proc = subprocess.run(
- fd_param,
- stdin=subprocess.DEVNULL,
- stdout=subprocess.PIPE,
- stderr=subprocess.STDOUT,
- check=False,
- close_fds=False,
- )
- if proc.stdout:
- LOG.debug(proc.stdout)
-
- return proc.returncode
+ return 0
@staticmethod
def _remove_if_exists(path: str) -> None:
diff --git a/python/qemu/qmp/__init__.py b/python/qemu/qmp/__init__.py
index ba15668c25..c3b8a70ec9 100644
--- a/python/qemu/qmp/__init__.py
+++ b/python/qemu/qmp/__init__.py
@@ -21,6 +21,7 @@
import json
import logging
import socket
+import struct
from types import TracebackType
from typing import (
Any,
@@ -408,18 +409,14 @@ def settimeout(self, timeout: Optional[float]) -> None:
raise ValueError(msg)
self.__sock.settimeout(timeout)
- def get_sock_fd(self) -> int:
+ def send_fd_scm(self, fd: int) -> None:
"""
- Get the socket file descriptor.
-
- @return The file descriptor number.
- """
- return self.__sock.fileno()
-
- def is_scm_available(self) -> bool:
+ Send a file descriptor to the remote via SCM_RIGHTS.
"""
- Check if the socket allows for SCM_RIGHTS.
+ if self.__sock.family != socket.AF_UNIX:
+ raise RuntimeError("Can't use SCM_RIGHTS on non-AF_UNIX socket.")
- @return True if SCM_RIGHTS is available, otherwise False.
- """
- return self.__sock.family == socket.AF_UNIX
+ self.__sock.sendmsg(
+ [b' '],
+ [(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack('@i', fd))]
+ )
--
2.31.1
- [PATCH 00/15] Switch iotests to using Async QMP, John Snow, 2021/09/17
- [PATCH 02/15] python/aqmp: add .empty() method to EventListener, John Snow, 2021/09/17
- [PATCH 04/15] python/qmp: clear events on get_events() call, John Snow, 2021/09/17
- [PATCH 05/15] python/qmp: add send_fd_scm directly to QEMUMonitorProtocol,
John Snow <=
- [PATCH 01/15] python/aqmp: add greeting property to QMPClient, John Snow, 2021/09/17
- [PATCH 03/15] python/aqmp: Return cleared events from EventListener.clear(), John Snow, 2021/09/17
- [PATCH 07/15] python/aqmp: add send_fd_scm, John Snow, 2021/09/17