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"""Exported method Container.attach()."""
import fcntl
import os
import select
import signal
import socket
import struct
import sys
import termios
import tty
CONMON_BUFSZ = 8192
class Mixin:
"""Publish attach() for inclusion in Container class."""
def attach(self, eot=4, stdin=None, stdout=None):
"""Attach to container's PID1 stdin and stdout.
stderr is ignored.
"""
if not self.containerrunning:
raise Exception('you can only attach to running containers')
if stdin is None:
stdin = sys.stdin.fileno()
if stdout is None:
stdout = sys.stdout.fileno()
with self._client() as podman:
attach = podman.GetAttachSockets(self._id)
# This is the UDS where all the IO goes
io_socket = attach['sockets']['io_socket']
assert len(io_socket) <= 107,\
'Path length for sockets too long. {} > 107'.format(
len(io_socket)
)
# This is the control socket where resizing events are sent to conmon
ctl_socket = attach['sockets']['control_socket']
def resize_handler(signum, frame):
"""Send the new window size to conmon.
The method arguments are not used.
"""
packed = fcntl.ioctl(stdout, termios.TIOCGWINSZ,
struct.pack('HHHH', 0, 0, 0, 0))
rows, cols, _, _ = struct.unpack('HHHH', packed)
# TODO: Need some kind of timeout in case pipe is blocked
with open(ctl_socket, 'w') as skt:
# send conmon window resize message
skt.write('1 {} {}\n'.format(rows, cols))
def log_handler(signum, frame):
"""Send command to reopen log to conmon.
The method arguments are not used.
"""
with open(ctl_socket, 'w') as skt:
# send conmon reopen log message
skt.write('2\n')
try:
# save off the old settings for terminal
original_attr = termios.tcgetattr(stdout)
tty.setraw(stdin)
# initialize containers window size
resize_handler(None, sys._getframe(0))
# catch any resizing events and send the resize info
# to the control fifo "socket"
signal.signal(signal.SIGWINCH, resize_handler)
except termios.error:
original_attr = None
try:
# TODO: socket.SOCK_SEQPACKET may not be supported in Windows
with socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET) as skt:
# Prepare socket for communicating with conmon/container
skt.connect(io_socket)
skt.sendall(b'\n')
sources = [skt, stdin]
while sources:
readable, _, _ = select.select(sources, [], [])
if skt in readable:
data = skt.recv(CONMON_BUFSZ)
if not data:
sources.remove(skt)
# Remove source marker when writing
os.write(stdout, data[1:])
if stdin in readable:
data = os.read(stdin, CONMON_BUFSZ)
if not data:
sources.remove(stdin)
skt.sendall(data)
if eot in data:
sources.clear()
finally:
if original_attr:
termios.tcsetattr(stdout, termios.TCSADRAIN, original_attr)
signal.signal(signal.SIGWINCH, signal.SIG_DFL)
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