serve-stdio

#!/usr/bin/env python

from __future__ import print_function

import os, sys
import signal
import nclib

argiter = iter(sys.argv)
progname = next(argiter)
daemonize = False
show_stderr = None
bind_addr = '0.0.0.0'

def usage():
    print('Usage: %s [options] port command ...' % sys.argv[0])
    print('Options:')
    print('  -d       Daemonize, run in background')
    print('  -e       Redirect program\'s stderr to socket')
    print('  -E       Hide program\'s stderr')
    print('  -b addr  Bind to a specific address')
    sys.exit(1)

for arg in argiter:
    try:
        if arg == '-d':
            daemonize = True
        elif arg == '-e':
            show_stderr = True
        elif arg == '-E':
            show_stderr = False
        elif arg == '-b':
            bind_addr = next(argiter)
        else:
            break
    except StopIteration:
        usage()
else:
    usage()

try:
    port = int(arg) # pylint: disable=undefined-loop-variable
except (ValueError, NameError):
    usage()

def quote(s):
    return "'%s'" % s.replace("'", "'\"'\"'")

command = ' '.join(map(quote, argiter))
if command == '':
    usage()

if daemonize:
    p = os.fork()
    if p:
        print(p)
        sys.stdout.flush()
        os._exit(0)

children = []
def reap():
    i = 0
    while i < len(children):
        if children[i].poll() is not None:
            children.pop(i)
        else:
            i += 1

def cleanup(*args): # pylint: disable=unused-argument
    for child in children:
        child.kill() # not sure how effective this is, will probably only kill the shell...
    print()
    sys.exit(0)

signal.signal(signal.SIGTERM, cleanup)
signal.signal(signal.SIGINT, cleanup)

for client in nclib.TCPServer((bind_addr, port)):
    print('Accepted client %s:%d' % client.peer)
    children.append(nclib.Process.launch(command, client, stderr=show_stderr))
    client.close()
    reap()