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"""
QEMU Console Socket Module:
This python module implements a ConsoleSocket object,
which can drain a socket and optionally dump the bytes to file.
"""
# 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.
#
from collections import deque
import socket
import threading
import time
class ConsoleSocket(socket.socket):
"""
ConsoleSocket represents a socket attached to a char device.
Optionally (if drain==True), drains the socket and places the bytes
into an 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 debugging purposes.
"""
def __init__(self, address, file=None, drain=False):
self._recv_timeout_sec = 300
self._sleep_time = 0.5
self._buffer = deque()
socket.socket.__init__(self, socket.AF_UNIX, socket.SOCK_STREAM)
self.connect(address)
self._logfile = None
if file:
self._logfile = open(file, "w")
self._open = True
if drain:
self._drain_thread = self._thread_start()
else:
self._drain_thread = None
def _drain_fn(self):
"""Drains the socket and runs while the socket is open."""
while self._open:
try:
self._drain_socket()
except socket.timeout:
# The socket is expected to timeout since we set a
# short timeout to allow the thread to exit when
# self._open is set to False.
time.sleep(self._sleep_time)
def _thread_start(self):
"""Kick off a thread to drain the socket."""
# Configure socket to not block and timeout.
# This allows our drain thread to not block
# on recieve and exit smoothly.
socket.socket.setblocking(self, False)
socket.socket.settimeout(self, 1)
drain_thread = threading.Thread(target=self._drain_fn)
drain_thread.daemon = True
drain_thread.start()
return drain_thread
def close(self):
"""Close the base object and wait for the thread to terminate"""
if self._open:
self._open = False
if self._drain_thread is not None:
thread, self._drain_thread = self._drain_thread, None
thread.join()
socket.socket.close(self)
if self._logfile:
self._logfile.close()
self._logfile = None
def _drain_socket(self):
"""process arriving characters into in memory _buffer"""
data = socket.socket.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")
if self._logfile:
self._logfile.write("{}".format(string))
self._logfile.flush()
for c in string:
self._buffer.extend(c)
def recv(self, bufsize: int = 1, flags: int = 0) -> bytes:
"""Return chars from in memory buffer.
Maintains the same API as socket.socket.recv.
"""
if self._drain_thread is None:
# Not buffering the socket, pass thru to socket.
return socket.socket.recv(self, bufsize, flags)
assert not flags, "Cannot pass flags to recv() in drained mode"
start_time = time.time()
while len(self._buffer) < bufsize:
time.sleep(self._sleep_time)
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(bufsize)])
# 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 setblocking(self, value):
"""When not draining we pass thru to the socket,
since when draining we control socket blocking.
"""
if self._drain_thread is None:
socket.socket.setblocking(self, value)
def settimeout(self, seconds):
"""When not draining we pass thru to the socket,
since when draining we control the timeout.
"""
if seconds is not None:
self._recv_timeout_sec = seconds
if self._drain_thread is None:
socket.socket.settimeout(self, seconds)
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