xemu/python/qemu/console_socket.py
Robert Foley 0fc8f660c5 python/qemu: Add ConsoleSocket for optional use in QEMUMachine
We add the ConsoleSocket object, which has a socket interface
and which will consume all arriving characters on the
socket, placing them into an in memory buffer.
This will also provide those chars via recv() as
would a regular socket.
ConsoleSocket also has the option of dumping
the console bytes to a log file.

We also give QEMUMachine the option of using ConsoleSocket
to drain and to use for logging console to a file.
By default QEMUMachine does not use ConsoleSocket.

This is added in preparation for use by basevm.py in a later commit.
This is a workaround we found was needed for basevm.py since
there is a known issue where QEMU will hang waiting
for console characters to be consumed.

Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Cleber Rosa <crosa@redhat.com>
Signed-off-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Peter Puhov <peter.puhov@linaro.org>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200601211421.1277-9-robert.foley@linaro.org>
Message-Id: <20200701135652.1366-13-alex.bennee@linaro.org>
2020-07-11 15:53:00 +01:00

111 lines
3.7 KiB
Python

#!/usr/bin/env python3
#
# This python module implements a ConsoleSocket object which is
# designed always drain the socket itself, and place
# the bytes into a in memory buffer for later processing.
#
# Optionally a file path can be passed in and we will also
# dump the characters to this file for debug.
#
# Copyright 2020 Linaro
#
# Authors:
# Robert Foley <robert.foley@linaro.org>
#
# This code is licensed under the GPL version 2 or later. See
# the COPYING file in the top-level directory.
#
import asyncore
import socket
import threading
import io
import os
import sys
from collections import deque
import time
import traceback
class ConsoleSocket(asyncore.dispatcher):
def __init__(self, address, file=None):
self._recv_timeout_sec = 300
self._buffer = deque()
self._asyncore_thread = None
self._sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
self._sock.connect(address)
self._logfile = None
if file:
self._logfile = open(file, "w")
asyncore.dispatcher.__init__(self, sock=self._sock)
self._open = True
self._thread_start()
def _thread_start(self):
"""Kick off a thread to wait on the asyncore.loop"""
if self._asyncore_thread is not None:
return
self._asyncore_thread = threading.Thread(target=asyncore.loop,
kwargs={'timeout':1})
self._asyncore_thread.daemon = True
self._asyncore_thread.start()
def handle_close(self):
"""redirect close to base class"""
# Call the base class close, but not self.close() since
# handle_close() occurs in the context of the thread which
# self.close() attempts to join.
asyncore.dispatcher.close(self)
def close(self):
"""Close the base object and wait for the thread to terminate"""
if self._open:
self._open = False
asyncore.dispatcher.close(self)
if self._asyncore_thread is not None:
thread, self._asyncore_thread = self._asyncore_thread, None
thread.join()
if self._logfile:
self._logfile.close()
self._logfile = None
def handle_read(self):
"""process arriving characters into in memory _buffer"""
try:
data = asyncore.dispatcher.recv(self, 1)
# latin1 is needed since there are some chars
# we are receiving that cannot be encoded to utf-8
# such as 0xe2, 0x80, 0xA6.
string = data.decode("latin1")
except:
print("Exception seen.")
traceback.print_exc()
return
if self._logfile:
self._logfile.write("{}".format(string))
self._logfile.flush()
for c in string:
self._buffer.extend(c)
def recv(self, n=1, sleep_delay_s=0.1):
"""Return chars from in memory buffer"""
start_time = time.time()
while len(self._buffer) < n:
time.sleep(sleep_delay_s)
elapsed_sec = time.time() - start_time
if elapsed_sec > self._recv_timeout_sec:
raise socket.timeout
chars = ''.join([self._buffer.popleft() for i in range(n)])
# We choose to use latin1 to remain consistent with
# handle_read() and give back the same data as the user would
# receive if they were reading directly from the
# socket w/o our intervention.
return chars.encode("latin1")
def set_blocking(self):
"""Maintain compatibility with socket API"""
pass
def settimeout(self, seconds):
"""Set current timeout on recv"""
self._recv_timeout_sec = seconds