#!/usr/bin/python
"""
Script to demonstrate how combination of subprocess & rsync causes a telnetlib connection to fail.
David Antliff, Nov 2010
"""
import telnetlib
import subprocess
import time

# ******** change this to False to avoid the crash
crash = True

# Use Google's SMTP server as a demonstration
host = "smtp.gmail.com"
port = 25

# connect to a remote host with telnetlib
t = telnetlib.Telnet()
t.open(host, port)
time.sleep(1)
print("telnet", t.read_eager())

# THE FOLLOWING LINE DOES NOT SEEM TO CAUSE A PROBLEM
process = subprocess.Popen(["ssh", "-V"], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
output = process.communicate()[0]
retcode = process.returncode
print("ssh", retcode, output)

# query the telnet server
t.write("EHLO\r\n")
time.sleep(1)
print("telnet", t.read_eager())

if crash:
    # THE FOLLOWING LINE KILLS THE telnetlib SOCKET
    process = subprocess.Popen(["rsync", "--version"], stdout=subprocess.PIPE)
    output = process.communicate()[0]
    retcode = process.returncode
    print("rsync", retcode, output[0:60])

# this will now result in a crash because the connection is lost:
print("telnet", t.read_eager())
t.write("QUIT\r\n")
t.close()