running VIM over UNIX socket

#!/usr/bin/python

import sys, os, socket, threading, subprocess, fcntl, select

class connector_t(threading.Thread):
    def __init__(self, inp, outp):
        threading.Thread.__init__(self)
        assert isinstance(inp, int)
        assert isinstance(outp, int)
        connector_t.set_non_block(inp)
        connector_t.set_non_block(outp)
        self.inp = inp
        self.outp = outp
        self.stop_flag = False
        self.name = "connector %d->%d" % (inp, outp)
    @staticmethod
    def set_non_block(fd):
        flag = fcntl.fcntl(fd, fcntl.F_GETFL)
        fcntl.fcntl(fd, fcntl.F_SETFL, flag | os.O_NONBLOCK)
    def stop(self):
        self.stop_flag = True
    def run(self):
        print self.name, "started"
        buff = ''
        while not self.stop_flag:
            select.select([self.inp], [self.outp], [], 1.0)
            try:
                text = os.read(self.inp, 1024)
                if len(text) > 0:
                    print self.name, "read", len(text), "bytes"
                buff += text
            except: pass
            try:
                res = os.write(self.outp, buff)
                if res > 0:
                    buff = buff[res:]
                    print self.name, "written", res, "bytes"
            except: pass

def main():
    s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    s.connect("/tmp/blah-socket")
    (master, slave) = os.openpty()
    print "master:", master, "s:", s
    cmd = sys.argv[1:]
    main_process = subprocess.Popen(cmd, stdin=slave, stdout=slave, stderr=slave, shell=False)
    print "starting cat1: copy master--->socket"
    cat1 = connector_t(master, s.fileno())
    cat1.start()
    print "starting cat2: copy socket->master"
    cat2 = connector_t(s.fileno(), master)
    cat2.start()
    print "waiting for main process (%s, pid=%d) to finish" % (cmd, main_process.pid)
    main_process.wait()
    print "main process finished"
    cat1.stop()
    cat2.stop()
    print "waiting for cat1"
    cat1.join()
    print "waiting for cat2"
    cat2.join()

if __name__ == "__main__":
    main()