"""Substitute for the forkpty system call, to support Solaris.
"""
import os
import errno
from pty import (STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, CHILD)
def fork_pty():
'''This implements a substitute for the forkpty system call. This
should be more portable than the pty.fork() function. Specifically,
this should work on Solaris.
Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to
resolve the issue with Python's pty.fork() not supporting Solaris,
particularly ssh. Based on patch to posixmodule.c authored by Noah
Spurrier::
http://mail.python.org/pipermail/python-dev/2003-May/035281.html
'''
parent_fd, child_fd = os.openpty()
if parent_fd < 0 or child_fd < 0:
raise OSError("os.openpty() failed")
pid = os.fork()
if pid == CHILD:
# Child.
os.close(parent_fd)
pty_make_controlling_tty(child_fd)
os.dup2(child_fd, STDIN_FILENO)
os.dup2(child_fd, STDOUT_FILENO)
os.dup2(child_fd, STDERR_FILENO)
else:
# Parent.
os.close(child_fd)
return pid, parent_fd
def pty_make_controlling_tty(tty_fd):
'''This makes the pseudo-terminal the controlling tty. This should be
more portable than the pty.fork() function. Specifically, this should
work on Solaris. '''
child_name = os.ttyname(tty_fd)
# Disconnect from controlling tty, if any. Raises OSError of ENXIO
# if there was no controlling tty to begin with, such as when
# executed by a cron(1) job.
try:
fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
os.close(fd)
except OSError as err:
if err.errno != errno.ENXIO:
raise
os.setsid()
# Verify we are disconnected from controlling tty by attempting to open
# it again. We expect that OSError of ENXIO should always be raised.
try:
fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
os.close(fd)
raise ExceptionPexpect("OSError of errno.ENXIO should be raised.")
except OSError as err:
if err.errno != errno.ENXIO:
raise
# Verify we can open child pty.
fd = os.open(child_name, os.O_RDWR)
os.close(fd)
# Verify we now have a controlling tty.
fd = os.open("/dev/tty", os.O_WRONLY)
os.close(fd)
