klipper-dgus/klippy/util.py

# Low level unix utility functions
#
# Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.

import os, pty, fcntl, termios, signal

# Return the SIGINT interrupt handler back to the OS default
def fix_sigint():
    signal.signal(signal.SIGINT, signal.SIG_DFL)
fix_sigint()

# Set a file-descriptor as non-blocking
def set_nonblock(fd):
    fcntl.fcntl(fd, fcntl.F_SETFL
                , fcntl.fcntl(fd, fcntl.F_GETFL) | os.O_NONBLOCK)

# Clear HUPCL flag
def clear_hupcl(fd):
    attrs = termios.tcgetattr(fd)
    attrs[2] = attrs[2] & ~termios.HUPCL
    termios.tcsetattr(fd, termios.TCSADRAIN, attrs)

# Support for creating a pseudo-tty for emulating a serial port
def create_pty(ptyname):
    mfd, sfd = pty.openpty()
    try:
        os.unlink(ptyname)
    except os.error:
        pass
    os.symlink(os.ttyname(sfd), ptyname)
    fcntl.fcntl(mfd, fcntl.F_SETFL
                , fcntl.fcntl(mfd, fcntl.F_GETFL) | os.O_NONBLOCK)
    old = termios.tcgetattr(mfd)
    old[3] = old[3] & ~termios.ECHO
    termios.tcsetattr(mfd, termios.TCSADRAIN, old)
    return mfd