test whether socket ignores signals

.gitignore

/.tox/
/*.egg-info/
/tox-*.egg/

README.markdown

Run python setup.py test to test whether socket ignores signals on various Python versions. If it does then the test hangs.

Or just:

$ pythonX.Y test_socket_ignore_signal.py

to test Python X.Y version.

server.py

#!/usr/bin/env python
"""Server program that doesn't respond.

From http://docs.python.org/release/3.3.0/library/socket.html
"""
import socket
import sys


def sprint(*args):
    print((("server",) + args))  # print tuple to support Python 2.4+

HOST = None  # Symbolic name meaning all available interfaces
if len(sys.argv) > 1:
    HOST, _, PORT = sys.argv[1].partition(':')
    PORT = int(PORT)
else:
    PORT = 31950  # arbitrary non-privileged port
s = None
for res in socket.getaddrinfo(HOST, PORT,
                              socket.AF_UNSPEC,
                              socket.SOCK_STREAM,
                              0,
                              socket.AI_PASSIVE):
    af, socktype, proto, canonname, sa = res
    sprint(sa)
    try:
        s = socket.socket(af, socktype, proto)
    except socket.error:  # use `socket.error` to support Python 2.4+
        s = None
        continue
    try:
        s.bind(sa)
        s.listen(1)
    except socket.error:
        s.close()
        s = None
        continue
    break
if s is None:
    sprint('could not open socket')
    sys.exit(1)
conn, addr = s.accept()
sprint('Connected by', addr)
while True:
    data = conn.recv(1024)
    if not data:
        break
    sprint(repr(data))
    # do not respond
conn.close()

setup.py

import sys
from setuptools import setup
from setuptools.command.test import test as TestCommand


# `python setup.py test` installs and runs `tox`
class Tox(TestCommand):
    def finalize_options(self):
        TestCommand.finalize_options(self)
        self.test_args = []
        self.test_suite = True

    def run_tests(self):
        #import here, cause outside the eggs aren't loaded
        import tox
        errno = tox.cmdline(self.test_args)
        sys.exit(errno)

setup(
    name='test-socket-ignore-signal',
    tests_require=['tox'],
    cmdclass={'test': Tox},
    url='https://gist.github.com/4069063',
    )

test_socket_ignore_signal.py

#!/usr/bin/env python
"""Test whether socket ignores signals."""
import os
import signal
import socket
import sys
import time
from subprocess import Popen


class Alarm(Exception):
    pass


def sigalrm_handler(signum, frame):
    raise Alarm


def sprint(*args):
    print((("client",) + args))  # print tuple to support Python 2.4+


def readline(host, port):
    """Read a single line from host:port.

    From  http://docs.python.org/release/3.3.0/library/socket.html
    """
    s = None
    for _ in range(10):
        for res in socket.getaddrinfo(host, port,
                                      socket.AF_UNSPEC, socket.SOCK_STREAM):
            af, socktype, proto, canonname, sa = res
            sprint(sa)
            try:
                s = socket.socket(af, socktype, proto)
            except socket.error:
                s = None
                continue
            try:
                s.connect(sa)
            except socket.error:
                s.close()
                s = None
                continue
            break
        else:
            # no break; server might not be ready yet
            if server_process.poll() is not None:
                break
            time.sleep(1)  # allow server to start
            continue
        break

    if s is None:
        sprint('could not open socket')
        sys.exit(1)
    s.sendall('Hello, world'.encode('ascii'))
    f = s.makefile('rb')
    try:
        data = f.readline()  # should block
    finally:
        f.close()
    s.close()
    sprint('Received', repr(data))
    return data

port = 12345
if len(sys.argv) > 1:
    host = sys.argv[1]
else:
    # get public network interface (according to docs)
    host = socket.gethostbyname(socket.gethostname())

# start server that doesn't respond
scriptdir = os.path.dirname(os.path.abspath(__file__))
server_script = os.path.join(scriptdir, 'server.py')
server_process = Popen([sys.executable, server_script, "%s:%s" % (host, port)])


# setup signal handler & alarm
signal.signal(signal.SIGALRM, sigalrm_handler)
delay = 3  # seconds
signal.alarm(delay)
sprint("wait %d seconds" % (delay,))
try:
    readline(host, port)
except Alarm:  # got alarm
    sprint('ALARM WORKS')
else:
    assert 0, "shouldn't get here, readline() must block"

tox.ini

[tox]
envlist = py25,py26,py27,pypy,py31,py32,py33

[testenv]
commands=
    python -V
    python test_socket_ignore_signal.py []