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confluent/misc/autocons.py
Jarrod Johnson b0d2d44b75 Update to follow DCD
The DCD signal can be used to detect remote connect attempt
2019-03-14 13:05:59 -04:00

91 lines
2.6 KiB
Python

import fcntl
import os
import signal
import struct
import subprocess
import termios
import time
addrtoname = {
0x3f8: '/dev/ttyS0',
0x2f8: '/dev/ttyS1',
0x3e8: '/dev/ttyS2',
0x2e8: '/dev/ttyS3',
}
speedmap = {
0: None,
3: 9600,
4: 19200,
6: 57600,
7: 115200,
}
termiobaud = {
9600: termios.B9600,
19200: termios.B19200,
57600: termios.B57600,
115200: termios.B115200,
}
def do_serial_config():
if 'console=ttyS' in open('/proc/cmdline').read():
return None # Do not do autoconsole if manually configured
spcr = open("/sys/firmware/acpi/tables/SPCR", "rb")
spcr = bytearray(spcr.read())
if spcr[8] != 2 or spcr[36] != 0 or spcr[40] != 1:
return None
address = struct.unpack('<Q', spcr[44:52])[0]
tty = None
try:
tty = addrtoname[address]
except KeyError:
return None
retval = { 'tty': tty }
try:
retval['speed'] = speedmap[spcr[58]]
except KeyError:
return None
if retval['speed']:
ttyf = os.open(tty, os.O_RDWR | os.O_NOCTTY)
currattr = termios.tcgetattr(ttyf)
currattr[4:6] = [0, termiobaud[retval['speed']]]
termios.tcsetattr(ttyf, termios.TCSANOW, currattr)
retval['connected'] = bool(struct.unpack('<I', fcntl.ioctl(
ttyf, termios.TIOCMGET, '\x00\x00\x00\x00'))[0] & termios.TIOCM_CAR)
os.close(ttyf)
return retval
def is_connected(tty):
ttyf = os.open(tty, os.O_RDWR | os.O_NOCTTY)
retval = bool(struct.unpack('<I', fcntl.ioctl(
ttyf, termios.TIOCMGET, '\x00\x00\x00\x00'))[0] & termios.TIOCM_CAR)
os.close(ttyf)
return retval
if __name__ == '__main__':
serialinfo = do_serial_config()
if serialinfo:
running = False
while True:
if running and running.poll() is not None:
running = False
if running and not is_connected(serialinfo['tty']):
try:
running.terminate()
running.wait()
except Exception:
pass
time.sleep(0.5)
running = subprocess.Popen(['/bin/sh', '-c', 'exec screen -x console <> {0} >&0 2>&1'.format(serialinfo['tty'])])
time.sleep(0.5)
try:
running.terminate()
running.wait()
except Exception:
pass
running = False
elif not running and is_connected(serialinfo['tty']):
running = subprocess.Popen(['/bin/sh', '-c', 'exec screen -x console <> {0} >&0 2>&1'.format(serialinfo['tty'])])
time.sleep(0.5)