One Hat Cyber Team

View File Name : test_twistd.py

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.application.app} and L{twisted.scripts.twistd}.
"""

from __future__ import absolute_import, division

import errno
import inspect
import signal
import os
import sys

try:
    import pwd
    import grp
except ImportError:
    pwd = grp = None

try:
    import cPickle as pickle
except ImportError:
    import pickle

from zope.interface import implementer
from zope.interface.verify import verifyObject

from twisted.trial import unittest
from twisted.test.test_process import MockOS

from twisted import plugin, logger, internet
from twisted.application import service, app, reactors
from twisted.application.service import IServiceMaker
from twisted.internet.defer import Deferred
from twisted.internet.interfaces import (IReactorDaemonize,
                                         _ISupportsExitSignalCapturing)
from twisted.internet.test.modulehelpers import AlternateReactor
from twisted.logger import globalLogBeginner, globalLogPublisher, ILogObserver
from twisted.internet.base import ReactorBase
from twisted.test.proto_helpers import MemoryReactor
from twisted.python.compat import NativeStringIO, _PY3
from twisted.python.components import Componentized
from twisted.python import util
from twisted.python.log import (ILogObserver as LegacyILogObserver,
                                textFromEventDict)
from twisted.python.runtime import platformType
from twisted.python.usage import UsageError
from twisted.python.fakepwd import UserDatabase
from twisted.scripts import twistd

try:
    from twisted.scripts import _twistd_unix
except ImportError:
    _twistd_unix = None
else:
    from twisted.scripts._twistd_unix import checkPID
    from twisted.scripts._twistd_unix import UnixApplicationRunner
    from twisted.scripts._twistd_unix import UnixAppLogger


try:
    from twisted.python import syslog
except ImportError:
    syslog = None


try:
    import profile
except ImportError:
    profile = None


try:
    import pstats
    import cProfile
except ImportError:
    cProfile = None

if getattr(os, 'setuid', None) is None:
    setuidSkip = "Platform does not support --uid/--gid twistd options."
else:
    setuidSkip = None



def patchUserDatabase(patch, user, uid, group, gid):
    """
    Patch L{pwd.getpwnam} so that it behaves as though only one user exists
    and patch L{grp.getgrnam} so that it behaves as though only one group
    exists.

    @param patch: A function like L{TestCase.patch} which will be used to
        install the fake implementations.

    @type user: C{str}
    @param user: The name of the single user which will exist.

    @type uid: C{int}
    @param uid: The UID of the single user which will exist.

    @type group: C{str}
    @param group: The name of the single user which will exist.

    @type gid: C{int}
    @param gid: The GID of the single group which will exist.
    """
    # Try not to be an unverified fake, but try not to depend on quirks of
    # the system either (eg, run as a process with a uid and gid which
    # equal each other, and so doesn't reliably test that uid is used where
    # uid should be used and gid is used where gid should be used). -exarkun
    pwent = pwd.getpwuid(os.getuid())
    grent = grp.getgrgid(os.getgid())

    database = UserDatabase()
    database.addUser(
        user, pwent.pw_passwd, uid, gid,
        pwent.pw_gecos, pwent.pw_dir, pwent.pw_shell)

    def getgrnam(name):
        result = list(grent)
        result[result.index(grent.gr_name)] = group
        result[result.index(grent.gr_gid)] = gid
        result = tuple(result)
        return {group: result}[name]

    patch(pwd, "getpwnam", database.getpwnam)
    patch(grp, "getgrnam", getgrnam)
    patch(pwd, "getpwuid", database.getpwuid)



class MockServiceMaker(object):
    """
    A non-implementation of L{twisted.application.service.IServiceMaker}.
    """
    tapname = 'ueoa'

    def makeService(self, options):
        """
        Take a L{usage.Options} instance and return a
        L{service.IService} provider.
        """
        self.options = options
        self.service = service.Service()
        return self.service



class CrippledAppLogger(app.AppLogger):
    """
    @see: CrippledApplicationRunner.
    """

    def start(self, application):
        pass



class CrippledApplicationRunner(twistd._SomeApplicationRunner):
    """
    An application runner that cripples the platform-specific runner and
    nasty side-effect-having code so that we can use it without actually
    running any environment-affecting code.
    """
    loggerFactory = CrippledAppLogger

    def preApplication(self):
        pass


    def postApplication(self):
        pass



class ServerOptionsTests(unittest.TestCase):
    """
    Non-platform-specific tests for the platform-specific ServerOptions class.
    """
    def test_subCommands(self):
        """
        subCommands is built from IServiceMaker plugins, and is sorted
        alphabetically.
        """
        class FakePlugin(object):
            def __init__(self, name):
                self.tapname = name
                self._options = 'options for ' + name
                self.description = 'description of ' + name

            def options(self):
                return self._options

        apple = FakePlugin('apple')
        banana = FakePlugin('banana')
        coconut = FakePlugin('coconut')
        donut = FakePlugin('donut')

        def getPlugins(interface):
            self.assertEqual(interface, IServiceMaker)
            yield coconut
            yield banana
            yield donut
            yield apple

        config = twistd.ServerOptions()
        self.assertEqual(config._getPlugins, plugin.getPlugins)
        config._getPlugins = getPlugins

        # "subCommands is a list of 4-tuples of (command name, command
        # shortcut, parser class, documentation)."
        subCommands = config.subCommands
        expectedOrder = [apple, banana, coconut, donut]

        for subCommand, expectedCommand in zip(subCommands, expectedOrder):
            name, shortcut, parserClass, documentation = subCommand
            self.assertEqual(name, expectedCommand.tapname)
            self.assertIsNone(shortcut)
            self.assertEqual(parserClass(), expectedCommand._options),
            self.assertEqual(documentation, expectedCommand.description)


    def test_sortedReactorHelp(self):
        """
        Reactor names are listed alphabetically by I{--help-reactors}.
        """
        class FakeReactorInstaller(object):
            def __init__(self, name):
                self.shortName = 'name of ' + name
                self.description = 'description of ' + name
                self.moduleName = 'twisted.internet.default'

        apple = FakeReactorInstaller('apple')
        banana = FakeReactorInstaller('banana')
        coconut = FakeReactorInstaller('coconut')
        donut = FakeReactorInstaller('donut')

        def getReactorTypes():
            yield coconut
            yield banana
            yield donut
            yield apple

        config = twistd.ServerOptions()
        self.assertEqual(config._getReactorTypes, reactors.getReactorTypes)
        config._getReactorTypes = getReactorTypes
        config.messageOutput = NativeStringIO()

        self.assertRaises(SystemExit, config.parseOptions, ['--help-reactors'])
        helpOutput = config.messageOutput.getvalue()
        indexes = []
        for reactor in apple, banana, coconut, donut:
            def getIndex(s):
                self.assertIn(s, helpOutput)
                indexes.append(helpOutput.index(s))

            getIndex(reactor.shortName)
            getIndex(reactor.description)

        self.assertEqual(
            indexes, sorted(indexes),
            'reactor descriptions were not in alphabetical order: %r' % (
                helpOutput,))


    def test_postOptionsSubCommandCausesNoSave(self):
        """
        postOptions should set no_save to True when a subcommand is used.
        """
        config = twistd.ServerOptions()
        config.subCommand = 'ueoa'
        config.postOptions()
        self.assertTrue(config['no_save'])


    def test_postOptionsNoSubCommandSavesAsUsual(self):
        """
        If no sub command is used, postOptions should not touch no_save.
        """
        config = twistd.ServerOptions()
        config.postOptions()
        self.assertFalse(config['no_save'])


    def test_listAllProfilers(self):
        """
        All the profilers that can be used in L{app.AppProfiler} are listed in
        the help output.
        """
        config = twistd.ServerOptions()
        helpOutput = str(config)
        for profiler in app.AppProfiler.profilers:
            self.assertIn(profiler, helpOutput)


    def test_defaultUmask(self):
        """
        The default value for the C{umask} option is L{None}.
        """
        config = twistd.ServerOptions()
        self.assertIsNone(config['umask'])


    def test_umask(self):
        """
        The value given for the C{umask} option is parsed as an octal integer
        literal.
        """
        config = twistd.ServerOptions()
        config.parseOptions(['--umask', '123'])
        self.assertEqual(config['umask'], 83)
        config.parseOptions(['--umask', '0123'])
        self.assertEqual(config['umask'], 83)


    def test_invalidUmask(self):
        """
        If a value is given for the C{umask} option which cannot be parsed as
        an integer, L{UsageError} is raised by L{ServerOptions.parseOptions}.
        """
        config = twistd.ServerOptions()
        self.assertRaises(UsageError, config.parseOptions,
                          ['--umask', 'abcdef'])

    if _twistd_unix is None:
        msg = "twistd unix not available"
        test_defaultUmask.skip = test_umask.skip = test_invalidUmask.skip = msg


    def test_unimportableConfiguredLogObserver(self):
        """
        C{--logger} with an unimportable module raises a L{UsageError}.
        """
        config = twistd.ServerOptions()
        e = self.assertRaises(
            UsageError, config.parseOptions,
            ['--logger', 'no.such.module.I.hope'])
        self.assertTrue(
            e.args[0].startswith(
                "Logger 'no.such.module.I.hope' could not be imported: "
                "'no.such.module.I.hope' does not name an object"))
        self.assertNotIn('\n', e.args[0])


    def test_badAttributeWithConfiguredLogObserver(self):
        """
        C{--logger} with a non-existent object raises a L{UsageError}.
        """
        config = twistd.ServerOptions()
        e = self.assertRaises(UsageError, config.parseOptions,
                              ["--logger", "twisted.test.test_twistd.FOOBAR"])
        if sys.version_info <= (3, 5):
            self.assertTrue(
                e.args[0].startswith(
                    "Logger 'twisted.test.test_twistd.FOOBAR' could not be "
                    "imported: 'module' object has no attribute 'FOOBAR'"))
        else:
            self.assertTrue(
                e.args[0].startswith(
                    "Logger 'twisted.test.test_twistd.FOOBAR' could not be "
                    "imported: module 'twisted.test.test_twistd' "
                    "has no attribute 'FOOBAR'"))
        self.assertNotIn('\n', e.args[0])


    def test_version(self):
        """
        C{--version} prints the version.
        """
        from twisted import copyright

        if platformType == "win32":
            name = "(the Twisted Windows runner)"
        else:
            name = "(the Twisted daemon)"
        expectedOutput = ('twistd {} {}\n{}\n'.format(
            name, copyright.version, copyright.copyright))

        stdout = NativeStringIO()
        config = twistd.ServerOptions(stdout=stdout)
        e = self.assertRaises(SystemExit, config.parseOptions, ['--version'])
        self.assertIs(e.code, None)
        self.assertEqual(stdout.getvalue(), expectedOutput)



class CheckPIDTests(unittest.TestCase):
    """
    Tests for L{checkPID}.
    """
    if _twistd_unix is None:
        skip = "twistd unix not available"


    def test_notExists(self):
        """
        Nonexistent PID file is not an error.
        """
        self.patch(os.path, "exists", lambda _: False)
        checkPID("non-existent PID file")


    def test_nonNumeric(self):
        """
        Non-numeric content in a PID file causes a system exit.
        """
        pidfile = self.mktemp()
        with open(pidfile, "w") as f:
            f.write("non-numeric")
        e = self.assertRaises(SystemExit, checkPID, pidfile)
        self.assertIn("non-numeric value", e.code)


    def test_anotherRunning(self):
        """
        Another running twistd server causes a system exit.
        """
        pidfile = self.mktemp()
        with open(pidfile, "w") as f:
            f.write("42")
        def kill(pid, sig):
            pass
        self.patch(os, "kill", kill)
        e = self.assertRaises(SystemExit, checkPID, pidfile)
        self.assertIn("Another twistd server", e.code)


    def test_stale(self):
        """
        Stale PID file is removed without causing a system exit.
        """
        pidfile = self.mktemp()
        with open(pidfile, "w") as f:
            f.write(str(os.getpid() + 1))
        def kill(pid, sig):
            raise OSError(errno.ESRCH, "fake")
        self.patch(os, "kill", kill)
        checkPID(pidfile)
        self.assertFalse(os.path.exists(pidfile))


    def test_unexpectedOSError(self):
        """
        An unexpected L{OSError} when checking the validity of a
        PID in a C{pidfile} terminates the process via L{SystemExit}.
        """
        pidfile = self.mktemp()
        with open(pidfile, "w") as f:
            f.write("3581")
        def kill(pid, sig):
            raise OSError(errno.EBADF, "fake")
        self.patch(os, "kill", kill)
        e = self.assertRaises(SystemExit, checkPID, pidfile)
        self.assertIsNot(e.code, None)
        self.assertTrue(e.args[0].startswith("Can't check status of PID"))


class TapFileTests(unittest.TestCase):
    """
    Test twistd-related functionality that requires a tap file on disk.
    """

    def setUp(self):
        """
        Create a trivial Application and put it in a tap file on disk.
        """
        self.tapfile = self.mktemp()
        with open(self.tapfile, 'wb') as f:
            pickle.dump(service.Application("Hi!"), f)


    def test_createOrGetApplicationWithTapFile(self):
        """
        Ensure that the createOrGetApplication call that 'twistd -f foo.tap'
        makes will load the Application out of foo.tap.
        """
        config = twistd.ServerOptions()
        config.parseOptions(['-f', self.tapfile])
        application = CrippledApplicationRunner(
            config).createOrGetApplication()
        self.assertEqual(service.IService(application).name, 'Hi!')



class TestLoggerFactory(object):
    """
    A logger factory for L{TestApplicationRunner}.
    """

    def __init__(self, runner):
        self.runner = runner


    def start(self, application):
        """
        Save the logging start on the C{runner} instance.
        """
        self.runner.order.append("log")
        self.runner.hadApplicationLogObserver = hasattr(self.runner,
                                                        'application')


    def stop(self):
        """
        Don't log anything.
        """



class TestApplicationRunner(app.ApplicationRunner):
    """
    An ApplicationRunner which tracks the environment in which its methods are
    called.
    """

    def __init__(self, options):
        app.ApplicationRunner.__init__(self, options)
        self.order = []
        self.logger = TestLoggerFactory(self)


    def preApplication(self):
        self.order.append("pre")
        self.hadApplicationPreApplication = hasattr(self, 'application')


    def postApplication(self):
        self.order.append("post")
        self.hadApplicationPostApplication = hasattr(self, 'application')



class ApplicationRunnerTests(unittest.TestCase):
    """
    Non-platform-specific tests for the platform-specific ApplicationRunner.
    """
    def setUp(self):
        config = twistd.ServerOptions()
        self.serviceMaker = MockServiceMaker()
        # Set up a config object like it's been parsed with a subcommand
        config.loadedPlugins = {'test_command': self.serviceMaker}
        config.subOptions = object()
        config.subCommand = 'test_command'
        self.config = config


    def test_applicationRunnerGetsCorrectApplication(self):
        """
        Ensure that a twistd plugin gets used in appropriate ways: it
        is passed its Options instance, and the service it returns is
        added to the application.
        """
        arunner = CrippledApplicationRunner(self.config)
        arunner.run()

        self.assertIs(
            self.serviceMaker.options, self.config.subOptions,
            "ServiceMaker.makeService needs to be passed the correct "
            "sub Command object.")
        self.assertIs(
            self.serviceMaker.service,
            service.IService(arunner.application).services[0],
            "ServiceMaker.makeService's result needs to be set as a child "
            "of the Application.")


    def test_preAndPostApplication(self):
        """
        Test thet preApplication and postApplication methods are
        called by ApplicationRunner.run() when appropriate.
        """
        s = TestApplicationRunner(self.config)
        s.run()
        self.assertFalse(s.hadApplicationPreApplication)
        self.assertTrue(s.hadApplicationPostApplication)
        self.assertTrue(s.hadApplicationLogObserver)
        self.assertEqual(s.order, ["pre", "log", "post"])


    def _applicationStartsWithConfiguredID(self, argv, uid, gid):
        """
        Assert that given a particular command line, an application is started
        as a particular UID/GID.

        @param argv: A list of strings giving the options to parse.
        @param uid: An integer giving the expected UID.
        @param gid: An integer giving the expected GID.
        """
        self.config.parseOptions(argv)

        events = []

        class FakeUnixApplicationRunner(twistd._SomeApplicationRunner):
            def setupEnvironment(self, chroot, rundir, nodaemon, umask,
                                 pidfile):
                events.append('environment')

            def shedPrivileges(self, euid, uid, gid):
                events.append(('privileges', euid, uid, gid))

            def startReactor(self, reactor, oldstdout, oldstderr):
                events.append('reactor')

            def removePID(self, pidfile):
                pass

        @implementer(service.IService, service.IProcess)
        class FakeService(object):

            parent = None
            running = None
            name = None
            processName = None
            uid = None
            gid = None

            def setName(self, name):
                pass

            def setServiceParent(self, parent):
                pass

            def disownServiceParent(self):
                pass

            def privilegedStartService(self):
                events.append('privilegedStartService')

            def startService(self):
                events.append('startService')

            def stopService(self):
                pass

        application = FakeService()
        verifyObject(service.IService, application)
        verifyObject(service.IProcess, application)

        runner = FakeUnixApplicationRunner(self.config)
        runner.preApplication()
        runner.application = application
        runner.postApplication()

        self.assertEqual(
            events,
            ['environment', 'privilegedStartService',
             ('privileges', False, uid, gid), 'startService', 'reactor'])


    def test_applicationStartsWithConfiguredNumericIDs(self):
        """
        L{postApplication} should change the UID and GID to the values
        specified as numeric strings by the configuration after running
        L{service.IService.privilegedStartService} and before running
        L{service.IService.startService}.
        """
        uid = 1234
        gid = 4321
        self._applicationStartsWithConfiguredID(
            ["--uid", str(uid), "--gid", str(gid)], uid, gid)
    test_applicationStartsWithConfiguredNumericIDs.skip = setuidSkip


    def test_applicationStartsWithConfiguredNameIDs(self):
        """
        L{postApplication} should change the UID and GID to the values
        specified as user and group names by the configuration after running
        L{service.IService.privilegedStartService} and before running
        L{service.IService.startService}.
        """
        user = "foo"
        uid = 1234
        group = "bar"
        gid = 4321
        patchUserDatabase(self.patch, user, uid, group, gid)
        self._applicationStartsWithConfiguredID(
            ["--uid", user, "--gid", group], uid, gid)
    test_applicationStartsWithConfiguredNameIDs.skip = setuidSkip


    def test_startReactorRunsTheReactor(self):
        """
        L{startReactor} calls L{reactor.run}.
        """
        reactor = DummyReactor()
        runner = app.ApplicationRunner({
            "profile": False,
            "profiler": "profile",
            "debug": False})
        runner.startReactor(reactor, None, None)
        self.assertTrue(
            reactor.called, "startReactor did not call reactor.run()")


    def test_applicationRunnerChoosesReactorIfNone(self):
        """
        L{ApplicationRunner} chooses a reactor if none is specified.
        """
        reactor = DummyReactor()
        self.patch(internet, 'reactor', reactor)
        runner = app.ApplicationRunner({
            "profile": False,
            "profiler": "profile",
            "debug": False})
        runner.startReactor(None, None, None)
        self.assertTrue(reactor.called)


    def test_applicationRunnerCapturesSignal(self):
        """
        If the reactor exits with a signal, the application runner caches
        the signal.
        """

        class DummyReactorWithSignal(ReactorBase):
            """
            A dummy reactor, providing a C{run} method, and setting the
            _exitSignal attribute to a nonzero value.
            """

            def installWaker(self):
                """
                Dummy method, does nothing.
                """

            def run(self):
                """
                A fake run method setting _exitSignal to a nonzero value
                """
                self._exitSignal = 2

        reactor = DummyReactorWithSignal()
        runner = app.ApplicationRunner({
            "profile": False,
            "profiler": "profile",
            "debug": False})
        runner.startReactor(reactor, None, None)
        self.assertEquals(2, runner._exitSignal)


    def test_applicationRunnerIgnoresNoSignal(self):
        """
        The runner sets its _exitSignal instance attribute to None if
        the reactor does not implement L{_ISupportsExitSignalCapturing}.
        """

        class DummyReactorWithExitSignalAttribute(object):
            """
            A dummy reactor, providing a C{run} method, and setting the
            _exitSignal attribute to a nonzero value.
            """

            def installWaker(self):
                """
                Dummy method, does nothing.
                """

            def run(self):
                """
                A fake run method setting _exitSignal to a nonzero value
                that should be ignored.
                """
                self._exitSignal = 2

        reactor = DummyReactorWithExitSignalAttribute()
        runner = app.ApplicationRunner({
            "profile": False,
            "profiler": "profile",
            "debug": False})
        runner.startReactor(reactor, None, None)
        self.assertEquals(None, runner._exitSignal)



class UnixApplicationRunnerSetupEnvironmentTests(unittest.TestCase):
    """
    Tests for L{UnixApplicationRunner.setupEnvironment}.

    @ivar root: The root of the filesystem, or C{unset} if none has been
        specified with a call to L{os.chroot} (patched for this TestCase with
        L{UnixApplicationRunnerSetupEnvironmentTests.chroot}).

    @ivar cwd: The current working directory of the process, or C{unset} if
        none has been specified with a call to L{os.chdir} (patched for this
        TestCase with L{UnixApplicationRunnerSetupEnvironmentTests.chdir}).

    @ivar mask: The current file creation mask of the process, or C{unset} if
        none has been specified with a call to L{os.umask} (patched for this
        TestCase with L{UnixApplicationRunnerSetupEnvironmentTests.umask}).

    @ivar daemon: A boolean indicating whether daemonization has been performed
        by a call to L{_twistd_unix.daemonize} (patched for this TestCase with
        L{UnixApplicationRunnerSetupEnvironmentTests}.
    """
    if _twistd_unix is None:
        skip = "twistd unix not available"

    unset = object()

    def setUp(self):
        self.root = self.unset
        self.cwd = self.unset
        self.mask = self.unset
        self.daemon = False
        self.pid = os.getpid()
        self.patch(os, 'chroot', lambda path: setattr(self, 'root', path))
        self.patch(os, 'chdir', lambda path: setattr(self, 'cwd', path))
        self.patch(os, 'umask', lambda mask: setattr(self, 'mask', mask))
        self.runner = UnixApplicationRunner(twistd.ServerOptions())
        self.runner.daemonize = self.daemonize


    def daemonize(self, reactor):
        """
        Indicate that daemonization has happened and change the PID so that the
        value written to the pidfile can be tested in the daemonization case.
        """
        self.daemon = True
        self.patch(os, 'getpid', lambda: self.pid + 1)


    def test_chroot(self):
        """
        L{UnixApplicationRunner.setupEnvironment} changes the root of the
        filesystem if passed a non-L{None} value for the C{chroot} parameter.
        """
        self.runner.setupEnvironment("/foo/bar", ".", True, None, None)
        self.assertEqual(self.root, "/foo/bar")


    def test_noChroot(self):
        """
        L{UnixApplicationRunner.setupEnvironment} does not change the root of
        the filesystem if passed L{None} for the C{chroot} parameter.
        """
        self.runner.setupEnvironment(None, ".", True, None, None)
        self.assertIs(self.root, self.unset)


    def test_changeWorkingDirectory(self):
        """
        L{UnixApplicationRunner.setupEnvironment} changes the working directory
        of the process to the path given for the C{rundir} parameter.
        """
        self.runner.setupEnvironment(None, "/foo/bar", True, None, None)
        self.assertEqual(self.cwd, "/foo/bar")


    def test_daemonize(self):
        """
        L{UnixApplicationRunner.setupEnvironment} daemonizes the process if
        C{False} is passed for the C{nodaemon} parameter.
        """
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.setupEnvironment(None, ".", False, None, None)
        self.assertTrue(self.daemon)


    def test_noDaemonize(self):
        """
        L{UnixApplicationRunner.setupEnvironment} does not daemonize the
        process if C{True} is passed for the C{nodaemon} parameter.
        """
        self.runner.setupEnvironment(None, ".", True, None, None)
        self.assertFalse(self.daemon)


    def test_nonDaemonPIDFile(self):
        """
        L{UnixApplicationRunner.setupEnvironment} writes the process's PID to
        the file specified by the C{pidfile} parameter.
        """
        pidfile = self.mktemp()
        self.runner.setupEnvironment(None, ".", True, None, pidfile)
        with open(pidfile, 'rb') as f:
            pid = int(f.read())
        self.assertEqual(pid, self.pid)


    def test_daemonPIDFile(self):
        """
        L{UnixApplicationRunner.setupEnvironment} writes the daemonized
        process's PID to the file specified by the C{pidfile} parameter if
        C{nodaemon} is C{False}.
        """
        pidfile = self.mktemp()
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.setupEnvironment(None, ".", False, None, pidfile)
        with open(pidfile, 'rb') as f:
            pid = int(f.read())
        self.assertEqual(pid, self.pid + 1)


    def test_umask(self):
        """
        L{UnixApplicationRunner.setupEnvironment} changes the process umask to
        the value specified by the C{umask} parameter.
        """
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.setupEnvironment(None, ".", False, 123, None)
        self.assertEqual(self.mask, 123)


    def test_noDaemonizeNoUmask(self):
        """
        L{UnixApplicationRunner.setupEnvironment} doesn't change the process
        umask if L{None} is passed for the C{umask} parameter and C{True} is
        passed for the C{nodaemon} parameter.
        """
        self.runner.setupEnvironment(None, ".", True, None, None)
        self.assertIs(self.mask, self.unset)


    def test_daemonizedNoUmask(self):
        """
        L{UnixApplicationRunner.setupEnvironment} changes the process umask to
        C{0077} if L{None} is passed for the C{umask} parameter and C{False} is
        passed for the C{nodaemon} parameter.
        """
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.setupEnvironment(None, ".", False, None, None)
        self.assertEqual(self.mask, 0o077)


class UnixApplicationRunnerStartApplicationTests(unittest.TestCase):
    """
    Tests for L{UnixApplicationRunner.startApplication}.
    """
    if _twistd_unix is None:
        skip = "twistd unix not available"


    def test_setupEnvironment(self):
        """
        L{UnixApplicationRunner.startApplication} calls
        L{UnixApplicationRunner.setupEnvironment} with the chroot, rundir,
        nodaemon, umask, and pidfile parameters from the configuration it is
        constructed with.
        """
        options = twistd.ServerOptions()
        options.parseOptions([
            '--nodaemon',
            '--umask', '0070',
            '--chroot', '/foo/chroot',
            '--rundir', '/foo/rundir',
            '--pidfile', '/foo/pidfile'])
        application = service.Application("test_setupEnvironment")
        self.runner = UnixApplicationRunner(options)

        args = []
        def fakeSetupEnvironment(self, chroot, rundir, nodaemon, umask,
                                 pidfile):
            args.extend((chroot, rundir, nodaemon, umask, pidfile))

        # Sanity check
        if _PY3:
            setupEnvironmentParameters = \
                inspect.signature(self.runner.setupEnvironment).parameters
            fakeSetupEnvironmentParameters = \
                inspect.signature(fakeSetupEnvironment).parameters

            # inspect.signature() does not return "self" in the signature of
            # a class method, so we need to omit  it when comparing the
            # the signature of a plain method
            fakeSetupEnvironmentParameters = fakeSetupEnvironmentParameters.copy()
            fakeSetupEnvironmentParameters.pop("self")

            self.assertEqual(setupEnvironmentParameters,
                fakeSetupEnvironmentParameters)
        else:
            self.assertEqual(
                inspect.getargspec(self.runner.setupEnvironment),
                inspect.getargspec(fakeSetupEnvironment))

        self.patch(UnixApplicationRunner, 'setupEnvironment',
                   fakeSetupEnvironment)
        self.patch(UnixApplicationRunner, 'shedPrivileges',
                   lambda *a, **kw: None)
        self.patch(app, 'startApplication', lambda *a, **kw: None)
        self.runner.startApplication(application)

        self.assertEqual(
            args,
            ['/foo/chroot', '/foo/rundir', True, 56, '/foo/pidfile'])


    def test_shedPrivileges(self):
        """
        L{UnixApplicationRunner.shedPrivileges} switches the user ID
        of the process.
        """
        def switchUIDPass(uid, gid, euid):
            self.assertEqual(uid, 200)
            self.assertEqual(gid, 54)
            self.assertEqual(euid, 35)

        self.patch(_twistd_unix, 'switchUID', switchUIDPass)
        runner = UnixApplicationRunner({})
        runner.shedPrivileges(35, 200, 54)


    def test_shedPrivilegesError(self):
        """
        An unexpected L{OSError} when calling
        L{twisted.scripts._twistd_unix.shedPrivileges}
        terminates the process via L{SystemExit}.
        """
        def switchUIDFail(uid, gid, euid):
            raise OSError(errno.EBADF, "fake")

        runner = UnixApplicationRunner({})
        self.patch(_twistd_unix, 'switchUID', switchUIDFail)
        exc = self.assertRaises(SystemExit, runner.shedPrivileges, 35,
                                200, None)
        self.assertEqual(exc.code, 1)


    def _setUID(self, wantedUser, wantedUid, wantedGroup, wantedGid):
        """
        Common code for tests which try to pass the the UID to
        L{UnixApplicationRunner}.
        """
        patchUserDatabase(self.patch, wantedUser, wantedUid, wantedGroup,
                          wantedGid)

        def initgroups(uid, gid):
            self.assertEqual(uid, wantedUid)
            self.assertEqual(gid, wantedGid)

        def setuid(uid):
            self.assertEqual(uid, wantedUid)

        def setgid(gid):
            self.assertEqual(gid, wantedGid)

        self.patch(util, "initgroups", initgroups)
        self.patch(os, "setuid", setuid)
        self.patch(os, "setgid", setgid)

        options = twistd.ServerOptions()
        options.parseOptions([
            '--nodaemon',
            '--uid', str(wantedUid)])
        application = service.Application("test_setupEnvironment")
        self.runner = UnixApplicationRunner(options)
        runner = UnixApplicationRunner(options)
        runner.startApplication(application)


    def test_setUidWithoutGid(self):
        """
        Starting an application with L{UnixApplicationRunner} configured
        with a UID and no GUID will result in the GUID being
        set to the default GUID for that UID.
        """
        self._setUID("foo", 5151, "bar", 4242)


    def test_setUidSameAsCurrentUid(self):
        """
        If the specified UID is the same as the current UID of the process,
        then a warning is displayed.
        """
        currentUid = os.getuid()
        self._setUID("morefoo", currentUid, "morebar", 4343)

        warningsShown = self.flushWarnings()
        self.assertEqual(1, len(warningsShown))
        expectedWarning = (
            'tried to drop privileges and setuid {} but uid is already {}; '
            'should we be root? Continuing.'.format(currentUid, currentUid))
        self.assertEqual(expectedWarning, warningsShown[0]["message"])


class UnixApplicationRunnerRemovePIDTests(unittest.TestCase):
    """
    Tests for L{UnixApplicationRunner.removePID}.
    """
    if _twistd_unix is None:
        skip = "twistd unix not available"


    def test_removePID(self):
        """
        L{UnixApplicationRunner.removePID} deletes the file the name of
        which is passed to it.
        """
        runner = UnixApplicationRunner({})
        path = self.mktemp()
        os.makedirs(path)
        pidfile = os.path.join(path, "foo.pid")
        open(pidfile, "w").close()
        runner.removePID(pidfile)
        self.assertFalse(os.path.exists(pidfile))


    def test_removePIDErrors(self):
        """
        Calling L{UnixApplicationRunner.removePID} with a non-existent filename
        logs an OSError.
        """
        runner = UnixApplicationRunner({})
        runner.removePID("fakepid")
        errors = self.flushLoggedErrors(OSError)
        self.assertEqual(len(errors), 1)
        self.assertEqual(errors[0].value.errno, errno.ENOENT)



class FakeNonDaemonizingReactor(object):
    """
    A dummy reactor, providing C{beforeDaemonize} and C{afterDaemonize}
    methods, but not announcing this, and logging whether the methods have been
    called.

    @ivar _beforeDaemonizeCalled: if C{beforeDaemonize} has been called or not.
    @type _beforeDaemonizeCalled: C{bool}
    @ivar _afterDaemonizeCalled: if C{afterDaemonize} has been called or not.
    @type _afterDaemonizeCalled: C{bool}
    """

    def __init__(self):
        self._beforeDaemonizeCalled = False
        self._afterDaemonizeCalled = False


    def beforeDaemonize(self):
        self._beforeDaemonizeCalled = True


    def afterDaemonize(self):
        self._afterDaemonizeCalled = True


    def addSystemEventTrigger(self, *args, **kw):
        """
        Skip event registration.
        """



@implementer(IReactorDaemonize)
class FakeDaemonizingReactor(FakeNonDaemonizingReactor):
    """
    A dummy reactor, providing C{beforeDaemonize} and C{afterDaemonize}
    methods, announcing this, and logging whether the methods have been called.
    """



class DummyReactor(object):
    """
    A dummy reactor, only providing a C{run} method and checking that it
    has been called.

    @ivar called: if C{run} has been called or not.
    @type called: C{bool}
    """
    called = False

    def run(self):
        """
        A fake run method, checking that it's been called one and only time.
        """
        if self.called:
            raise RuntimeError("Already called")
        self.called = True



class AppProfilingTests(unittest.TestCase):
    """
    Tests for L{app.AppProfiler}.
    """

    def test_profile(self):
        """
        L{app.ProfileRunner.run} should call the C{run} method of the reactor
        and save profile data in the specified file.
        """
        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "profile"
        profiler = app.AppProfiler(config)
        reactor = DummyReactor()

        profiler.run(reactor)

        self.assertTrue(reactor.called)
        with open(config["profile"]) as f:
            data = f.read()
        self.assertIn("DummyReactor.run", data)
        self.assertIn("function calls", data)

    if profile is None:
        test_profile.skip = "profile module not available"


    def _testStats(self, statsClass, profile):
        out = NativeStringIO()

        # Patch before creating the pstats, because pstats binds self.stream to
        # sys.stdout early in 2.5 and newer.
        stdout = self.patch(sys, 'stdout', out)

        # If pstats.Stats can load the data and then reformat it, then the
        # right thing probably happened.
        stats = statsClass(profile)
        stats.print_stats()
        stdout.restore()

        data = out.getvalue()
        self.assertIn("function calls", data)
        self.assertIn("(run)", data)


    def test_profileSaveStats(self):
        """
        With the C{savestats} option specified, L{app.ProfileRunner.run}
        should save the raw stats object instead of a summary output.
        """
        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "profile"
        config["savestats"] = True
        profiler = app.AppProfiler(config)
        reactor = DummyReactor()

        profiler.run(reactor)

        self.assertTrue(reactor.called)
        self._testStats(pstats.Stats, config['profile'])

    if profile is None:
        test_profileSaveStats.skip = "profile module not available"


    def test_withoutProfile(self):
        """
        When the C{profile} module is not present, L{app.ProfilerRunner.run}
        should raise a C{SystemExit} exception.
        """
        savedModules = sys.modules.copy()

        config = twistd.ServerOptions()
        config["profiler"] = "profile"
        profiler = app.AppProfiler(config)

        sys.modules["profile"] = None
        try:
            self.assertRaises(SystemExit, profiler.run, None)
        finally:
            sys.modules.clear()
            sys.modules.update(savedModules)


    def test_profilePrintStatsError(self):
        """
        When an error happens during the print of the stats, C{sys.stdout}
        should be restored to its initial value.
        """
        class ErroneousProfile(profile.Profile):
            def print_stats(self):
                raise RuntimeError("Boom")
        self.patch(profile, "Profile", ErroneousProfile)

        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "profile"
        profiler = app.AppProfiler(config)
        reactor = DummyReactor()

        oldStdout = sys.stdout
        self.assertRaises(RuntimeError, profiler.run, reactor)
        self.assertIs(sys.stdout, oldStdout)

    if profile is None:
        test_profilePrintStatsError.skip = "profile module not available"


    def test_cProfile(self):
        """
        L{app.CProfileRunner.run} should call the C{run} method of the
        reactor and save profile data in the specified file.
        """
        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "cProfile"
        profiler = app.AppProfiler(config)
        reactor = DummyReactor()

        profiler.run(reactor)

        self.assertTrue(reactor.called)
        with open(config["profile"]) as f:
            data = f.read()
        self.assertIn("run", data)
        self.assertIn("function calls", data)

    if cProfile is None:
        test_cProfile.skip = "cProfile module not available"


    def test_cProfileSaveStats(self):
        """
        With the C{savestats} option specified,
        L{app.CProfileRunner.run} should save the raw stats object
        instead of a summary output.
        """
        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "cProfile"
        config["savestats"] = True
        profiler = app.AppProfiler(config)
        reactor = DummyReactor()

        profiler.run(reactor)

        self.assertTrue(reactor.called)
        self._testStats(pstats.Stats, config['profile'])

    if cProfile is None:
        test_cProfileSaveStats.skip = "cProfile module not available"


    def test_withoutCProfile(self):
        """
        When the C{cProfile} module is not present,
        L{app.CProfileRunner.run} should raise a C{SystemExit}
        exception and log the C{ImportError}.
        """
        savedModules = sys.modules.copy()
        sys.modules["cProfile"] = None

        config = twistd.ServerOptions()
        config["profiler"] = "cProfile"
        profiler = app.AppProfiler(config)
        try:
            self.assertRaises(SystemExit, profiler.run, None)
        finally:
            sys.modules.clear()
            sys.modules.update(savedModules)


    def test_unknownProfiler(self):
        """
        Check that L{app.AppProfiler} raises L{SystemExit} when given an
        unknown profiler name.
        """
        config = twistd.ServerOptions()
        config["profile"] = self.mktemp()
        config["profiler"] = "foobar"

        error = self.assertRaises(SystemExit, app.AppProfiler, config)
        self.assertEqual(str(error), "Unsupported profiler name: foobar")


    def test_defaultProfiler(self):
        """
        L{app.Profiler} defaults to the cprofile profiler if not specified.
        """
        profiler = app.AppProfiler({})
        self.assertEqual(profiler.profiler, "cprofile")


    def test_profilerNameCaseInsentive(self):
        """
        The case of the profiler name passed to L{app.AppProfiler} is not
        relevant.
        """
        profiler = app.AppProfiler({"profiler": "CprOfile"})
        self.assertEqual(profiler.profiler, "cprofile")



def _patchTextFileLogObserver(patch):
    """
    Patch L{logger.textFileLogObserver} to record every call and keep a
    reference to the passed log file for tests.

    @param patch: a callback for patching (usually L{unittest.TestCase.patch}).

    @return: the list that keeps track of the log files.
    @rtype: C{list}
    """
    logFiles = []
    oldFileLogObserver = logger.textFileLogObserver

    def observer(logFile, *args, **kwargs):
        logFiles.append(logFile)
        return oldFileLogObserver(logFile, *args, **kwargs)

    patch(logger, 'textFileLogObserver', observer)
    return logFiles



def _setupSyslog(testCase):
    """
    Make fake syslog, and return list to which prefix and then log
    messages will be appended if it is used.
    """
    logMessages = []

    class fakesyslogobserver(object):
        def __init__(self, prefix):
            logMessages.append(prefix)

        def emit(self, eventDict):
            logMessages.append(eventDict)

    testCase.patch(syslog, "SyslogObserver", fakesyslogobserver)
    return logMessages



class AppLoggerTests(unittest.TestCase):
    """
    Tests for L{app.AppLogger}.

    @ivar observers: list of observers installed during the tests.
    @type observers: C{list}
    """

    def setUp(self):
        """
        Override L{globaLogBeginner.beginLoggingTo} so that we can trace the
        observers installed in C{self.observers}.
        """
        self.observers = []

        def beginLoggingTo(observers):
            for observer in observers:
                self.observers.append(observer)
                globalLogPublisher.addObserver(observer)

        self.patch(globalLogBeginner, 'beginLoggingTo', beginLoggingTo)


    def tearDown(self):
        """
        Remove all installed observers.
        """
        for observer in self.observers:
            globalLogPublisher.removeObserver(observer)


    def _makeObserver(self):
        """
        Make a new observer which captures all logs sent to it.

        @return: An observer that stores all logs sent to it.
        @rtype: Callable that implements L{ILogObserver}.
        """
        @implementer(ILogObserver)
        class TestObserver(object):
            _logs = []

            def __call__(self, event):
                self._logs.append(event)

        return TestObserver()


    def _checkObserver(self, observer):
        """
        Ensure that initial C{twistd} logs are written to logs.

        @param observer: The observer made by L{self._makeObserver).
        """
        self.assertEqual(self.observers, [observer])
        self.assertIn("starting up", observer._logs[0]["log_format"])
        self.assertIn("reactor class", observer._logs[1]["log_format"])


    def test_start(self):
        """
        L{app.AppLogger.start} calls L{globalLogBeginner.addObserver}, and then
        writes some messages about twistd and the reactor.
        """
        logger = app.AppLogger({})
        observer = self._makeObserver()
        logger._getLogObserver = lambda: observer
        logger.start(Componentized())
        self._checkObserver(observer)


    def test_startUsesApplicationLogObserver(self):
        """
        When the L{ILogObserver} component is available on the application,
        that object will be used as the log observer instead of constructing a
        new one.
        """
        application = Componentized()
        observer = self._makeObserver()
        application.setComponent(ILogObserver, observer)
        logger = app.AppLogger({})
        logger.start(application)
        self._checkObserver(observer)


    def _setupConfiguredLogger(self, application, extraLogArgs={},
                               appLogger=app.AppLogger):
        """
        Set up an AppLogger which exercises the C{logger} configuration option.

        @type application: L{Componentized}
        @param application: The L{Application} object to pass to
            L{app.AppLogger.start}.
        @type extraLogArgs: C{dict}
        @param extraLogArgs: extra values to pass to AppLogger.
        @type appLogger: L{AppLogger} class, or a subclass
        @param appLogger: factory for L{AppLogger} instances.

        @rtype: C{list}
        @return: The logs accumulated by the log observer.
        """
        observer = self._makeObserver()
        logArgs = {"logger": lambda: observer}
        logArgs.update(extraLogArgs)
        logger = appLogger(logArgs)
        logger.start(application)
        return observer


    def test_startUsesConfiguredLogObserver(self):
        """
        When the C{logger} key is specified in the configuration dictionary
        (i.e., when C{--logger} is passed to twistd), the initial log observer
        will be the log observer returned from the callable which the value
        refers to in FQPN form.
        """
        application = Componentized()
        self._checkObserver(self._setupConfiguredLogger(application))


    def test_configuredLogObserverBeatsComponent(self):
        """
        C{--logger} takes precedence over a L{ILogObserver} component set on
        Application.
        """
        observer = self._makeObserver()
        application = Componentized()
        application.setComponent(ILogObserver, observer)
        self._checkObserver(self._setupConfiguredLogger(application))
        self.assertEqual(observer._logs, [])


    def test_configuredLogObserverBeatsLegacyComponent(self):
        """
        C{--logger} takes precedence over a L{LegacyILogObserver} component
        set on Application.
        """
        nonlogs = []
        application = Componentized()
        application.setComponent(LegacyILogObserver, nonlogs.append)
        self._checkObserver(self._setupConfiguredLogger(application))
        self.assertEqual(nonlogs, [])


    def test_loggerComponentBeatsLegacyLoggerComponent(self):
        """
        A L{ILogObserver} takes precedence over a L{LegacyILogObserver}
        component set on Application.
        """
        nonlogs = []
        observer = self._makeObserver()
        application = Componentized()
        application.setComponent(ILogObserver, observer)
        application.setComponent(LegacyILogObserver, nonlogs.append)

        logger = app.AppLogger({})
        logger.start(application)

        self._checkObserver(observer)
        self.assertEqual(nonlogs, [])


    def test_configuredLogObserverBeatsSyslog(self):
        """
        C{--logger} takes precedence over a C{--syslog} command line
        argument.
        """
        logs = _setupSyslog(self)
        application = Componentized()
        self._checkObserver(self._setupConfiguredLogger(application,
                                                        {"syslog": True},
                                                        UnixAppLogger))
        self.assertEqual(logs, [])

    if _twistd_unix is None or syslog is None:
        test_configuredLogObserverBeatsSyslog.skip = (
            "Not on POSIX, or syslog not available."
        )


    def test_configuredLogObserverBeatsLogfile(self):
        """
        C{--logger} takes precedence over a C{--logfile} command line
        argument.
        """
        application = Componentized()
        path = self.mktemp()
        self._checkObserver(self._setupConfiguredLogger(application,
                                                        {"logfile": "path"}))
        self.assertFalse(os.path.exists(path))


    def test_getLogObserverStdout(self):
        """
        When logfile is empty or set to C{-}, L{app.AppLogger._getLogObserver}
        returns a log observer pointing at C{sys.stdout}.
        """
        logger = app.AppLogger({"logfile": "-"})
        logFiles = _patchTextFileLogObserver(self.patch)

        logger._getLogObserver()

        self.assertEqual(len(logFiles), 1)
        self.assertIs(logFiles[0], sys.stdout)

        logger = app.AppLogger({"logfile": ""})
        logger._getLogObserver()

        self.assertEqual(len(logFiles), 2)
        self.assertIs(logFiles[1], sys.stdout)


    def test_getLogObserverFile(self):
        """
        When passing the C{logfile} option, L{app.AppLogger._getLogObserver}
        returns a log observer pointing at the specified path.
        """
        logFiles = _patchTextFileLogObserver(self.patch)
        filename = self.mktemp()
        logger = app.AppLogger({"logfile": filename})

        logger._getLogObserver()

        self.assertEqual(len(logFiles), 1)
        self.assertEqual(logFiles[0].path,
                         os.path.abspath(filename))


    def test_stop(self):
        """
        L{app.AppLogger.stop} removes the observer created in C{start}, and
        reinitialize its C{_observer} so that if C{stop} is called several
        times it doesn't break.
        """
        removed = []
        observer = object()

        def remove(observer):
            removed.append(observer)

        self.patch(globalLogPublisher, 'removeObserver', remove)
        logger = app.AppLogger({})
        logger._observer = observer
        logger.stop()
        self.assertEqual(removed, [observer])
        logger.stop()
        self.assertEqual(removed, [observer])
        self.assertIsNone(logger._observer)


    def test_legacyObservers(self):
        """
        L{app.AppLogger} using a legacy logger observer still works, wrapping
        it in a compat shim.
        """
        logs = []
        logger = app.AppLogger({})

        @implementer(LegacyILogObserver)
        class LoggerObserver(object):
            """
            An observer which implements the legacy L{LegacyILogObserver}.
            """
            def __call__(self, x):
                """
                Add C{x} to the logs list.
                """
                logs.append(x)

        logger._observerFactory = lambda: LoggerObserver()
        logger.start(Componentized())

        self.assertIn("starting up", textFromEventDict(logs[0]))
        warnings = self.flushWarnings(
            [self.test_legacyObservers])
        self.assertEqual(len(warnings), 0)


    def test_unmarkedObserversDeprecated(self):
        """
        L{app.AppLogger} using a logger observer which does not implement
        L{ILogObserver} or L{LegacyILogObserver} will be wrapped in a compat
        shim and raise a L{DeprecationWarning}.
        """
        logs = []
        logger = app.AppLogger({})
        logger._getLogObserver = lambda: logs.append
        logger.start(Componentized())

        self.assertIn("starting up", textFromEventDict(logs[0]))

        warnings = self.flushWarnings(
            [self.test_unmarkedObserversDeprecated])
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]["message"],
                         ("Passing a logger factory which makes log observers "
                          "which do not implement twisted.logger.ILogObserver "
                          "or twisted.python.log.ILogObserver to "
                          "twisted.application.app.AppLogger was deprecated "
                          "in Twisted 16.2. Please use a factory that "
                          "produces twisted.logger.ILogObserver (or the "
                          "legacy twisted.python.log.ILogObserver) "
                          "implementing objects instead."))



class UnixAppLoggerTests(unittest.TestCase):
    """
    Tests for L{UnixAppLogger}.

    @ivar signals: list of signal handlers installed.
    @type signals: C{list}
    """
    if _twistd_unix is None:
        skip = "twistd unix not available"


    def setUp(self):
        """
        Fake C{signal.signal} for not installing the handlers but saving them
        in C{self.signals}.
        """
        self.signals = []

        def fakeSignal(sig, f):
            self.signals.append((sig, f))

        self.patch(signal, "signal", fakeSignal)


    def test_getLogObserverStdout(self):
        """
        When non-daemonized and C{logfile} is empty or set to C{-},
        L{UnixAppLogger._getLogObserver} returns a log observer pointing at
        C{sys.stdout}.
        """
        logFiles = _patchTextFileLogObserver(self.patch)

        logger = UnixAppLogger({"logfile": "-", "nodaemon": True})
        logger._getLogObserver()
        self.assertEqual(len(logFiles), 1)
        self.assertIs(logFiles[0], sys.stdout)

        logger = UnixAppLogger({"logfile": "", "nodaemon": True})
        logger._getLogObserver()
        self.assertEqual(len(logFiles), 2)
        self.assertIs(logFiles[1], sys.stdout)


    def test_getLogObserverStdoutDaemon(self):
        """
        When daemonized and C{logfile} is set to C{-},
        L{UnixAppLogger._getLogObserver} raises C{SystemExit}.
        """
        logger = UnixAppLogger({"logfile": "-", "nodaemon": False})
        error = self.assertRaises(SystemExit, logger._getLogObserver)
        self.assertEqual(str(error), "Daemons cannot log to stdout, exiting!")


    def test_getLogObserverFile(self):
        """
        When C{logfile} contains a file name, L{app.AppLogger._getLogObserver}
        returns a log observer pointing at the specified path, and a signal
        handler rotating the log is installed.
        """
        logFiles = _patchTextFileLogObserver(self.patch)
        filename = self.mktemp()
        logger = UnixAppLogger({"logfile": filename})
        logger._getLogObserver()

        self.assertEqual(len(logFiles), 1)
        self.assertEqual(logFiles[0].path, os.path.abspath(filename))

        self.assertEqual(len(self.signals), 1)
        self.assertEqual(self.signals[0][0], signal.SIGUSR1)

        d = Deferred()

        def rotate():
            d.callback(None)

        logFiles[0].rotate = rotate

        rotateLog = self.signals[0][1]
        rotateLog(None, None)
        return d


    def test_getLogObserverDontOverrideSignalHandler(self):
        """
        If a signal handler is already installed,
        L{UnixAppLogger._getLogObserver} doesn't override it.
        """
        def fakeGetSignal(sig):
            self.assertEqual(sig, signal.SIGUSR1)
            return object()
        self.patch(signal, "getsignal", fakeGetSignal)
        filename = self.mktemp()
        logger = UnixAppLogger({"logfile": filename})
        logger._getLogObserver()

        self.assertEqual(self.signals, [])


    def test_getLogObserverDefaultFile(self):
        """
        When daemonized and C{logfile} is empty, the observer returned by
        L{UnixAppLogger._getLogObserver} points at C{twistd.log} in the current
        directory.
        """
        logFiles = _patchTextFileLogObserver(self.patch)
        logger = UnixAppLogger({"logfile": "", "nodaemon": False})
        logger._getLogObserver()

        self.assertEqual(len(logFiles), 1)
        self.assertEqual(logFiles[0].path, os.path.abspath("twistd.log"))


    def test_getLogObserverSyslog(self):
        """
        If C{syslog} is set to C{True}, L{UnixAppLogger._getLogObserver} starts
        a L{syslog.SyslogObserver} with given C{prefix}.
        """
        logs = _setupSyslog(self)
        logger = UnixAppLogger({"syslog": True, "prefix": "test-prefix"})
        observer = logger._getLogObserver()
        self.assertEqual(logs, ["test-prefix"])
        observer({"a": "b"})
        self.assertEqual(logs, ["test-prefix", {"a": "b"}])

    if syslog is None:
        test_getLogObserverSyslog.skip = "Syslog not available"



class DaemonizeTests(unittest.TestCase):
    """
    Tests for L{_twistd_unix.UnixApplicationRunner} daemonization.
    """

    def setUp(self):
        self.mockos = MockOS()
        self.config = twistd.ServerOptions()
        self.patch(_twistd_unix, 'os', self.mockos)
        self.runner = _twistd_unix.UnixApplicationRunner(self.config)
        self.runner.application = service.Application("Hi!")
        self.runner.oldstdout = sys.stdout
        self.runner.oldstderr = sys.stderr
        self.runner.startReactor = lambda *args: None


    def test_success(self):
        """
        When double fork succeeded in C{daemonize}, the child process writes
        B{0} to the status pipe.
        """
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.postApplication()
        self.assertEqual(
            self.mockos.actions,
            [('chdir', '.'), ('umask', 0o077), ('fork', True), 'setsid',
             ('fork', True), ('write', -2, b'0'), ('unlink', 'twistd.pid')])
        self.assertEqual(self.mockos.closed, [-3, -2])


    def test_successInParent(self):
        """
        The parent process initiating the C{daemonize} call reads data from the
        status pipe and then exit the process.
        """
        self.mockos.child = False
        self.mockos.readData = b"0"
        with AlternateReactor(FakeDaemonizingReactor()):
            self.assertRaises(SystemError, self.runner.postApplication)
        self.assertEqual(
            self.mockos.actions,
            [('chdir', '.'), ('umask', 0o077), ('fork', True),
             ('read', -1, 100), ('exit', 0), ('unlink', 'twistd.pid')])
        self.assertEqual(self.mockos.closed, [-1])


    def test_successEINTR(self):
        """
        If the C{os.write} call to the status pipe raises an B{EINTR} error,
        the process child retries to write.
        """
        written = []

        def raisingWrite(fd, data):
            written.append((fd, data))
            if len(written) == 1:
                raise IOError(errno.EINTR)

        self.mockos.write = raisingWrite
        with AlternateReactor(FakeDaemonizingReactor()):
            self.runner.postApplication()
        self.assertEqual(
            self.mockos.actions,
            [('chdir', '.'), ('umask', 0o077), ('fork', True), 'setsid',
             ('fork', True), ('unlink', 'twistd.pid')])
        self.assertEqual(self.mockos.closed, [-3, -2])
        self.assertEqual([(-2, b'0'), (-2, b'0')], written)


    def test_successInParentEINTR(self):
        """
        If the C{os.read} call on the status pipe raises an B{EINTR} error, the
        parent child retries to read.
        """
        read = []

        def raisingRead(fd, size):
            read.append((fd, size))
            if len(read) == 1:
                raise IOError(errno.EINTR)
            return b"0"

        self.mockos.read = raisingRead
        self.mockos.child = False
        with AlternateReactor(FakeDaemonizingReactor()):
            self.assertRaises(SystemError, self.runner.postApplication)
        self.assertEqual(
            self.mockos.actions,
            [('chdir', '.'), ('umask', 0o077), ('fork', True),
             ('exit', 0), ('unlink', 'twistd.pid')])
        self.assertEqual(self.mockos.closed, [-1])
        self.assertEqual([(-1, 100), (-1, 100)], read)



    def assertErrorWritten(self, raised, reported):
        """
        Assert L{UnixApplicationRunner.postApplication} writes
        C{reported} to its status pipe if the service raises an
        exception whose message is C{raised}.
        """
        class FakeService(service.Service):

            def startService(self):
                raise RuntimeError(raised)

        errorService = FakeService()
        errorService.setServiceParent(self.runner.application)

        with AlternateReactor(FakeDaemonizingReactor()):
            self.assertRaises(RuntimeError, self.runner.postApplication)
        self.assertEqual(
            self.mockos.actions,
            [('chdir', '.'), ('umask', 0o077), ('fork', True), 'setsid',
             ('fork', True), ('write', -2, reported),
             ('unlink', 'twistd.pid')])
        self.assertEqual(self.mockos.closed, [-3, -2])



    def test_error(self):
        """
        If an error happens during daemonization, the child process writes the
        exception error to the status pipe.
        """
        self.assertErrorWritten(raised="Something is wrong",
                                reported=b'1 RuntimeError: Something is wrong')



    def test_unicodeError(self):
        """
        If an error happens during daemonization, and that error's
        message is Unicode, the child encodes the message as ascii
        with backslash Unicode code points.
        """
        self.assertErrorWritten(raised=u"\u2022",
                                reported=b'1 RuntimeError: \\u2022')



    def assertErrorInParentBehavior(self, readData, errorMessage,
                                    mockOSActions):
        """
        Make L{os.read} appear to return C{readData}, and assert that
        L{UnixApplicationRunner.postApplication} writes
        C{errorMessage} to standard error and executes the calls
        against L{os} functions specified in C{mockOSActions}.
        """
        self.mockos.child = False
        self.mockos.readData = readData
        errorIO = NativeStringIO()
        self.patch(sys, '__stderr__', errorIO)
        with AlternateReactor(FakeDaemonizingReactor()):
            self.assertRaises(SystemError, self.runner.postApplication)
        self.assertEqual(errorIO.getvalue(), errorMessage)
        self.assertEqual(self.mockos.actions, mockOSActions)
        self.assertEqual(self.mockos.closed, [-1])


    def test_errorInParent(self):
        """
        When the child writes an error message to the status pipe
        during daemonization, the parent writes the repr of the
        message to C{stderr} and exits with non-zero status code.
        """
        self.assertErrorInParentBehavior(
            readData=b"1 Exception: An identified error",
            errorMessage=(
                "An error has occurred: b'Exception: An identified error'\n"
                "Please look at log file for more information.\n"),
            mockOSActions=[
                ('chdir', '.'), ('umask', 0o077), ('fork', True),
                ('read', -1, 100), ('exit', 1), ('unlink', 'twistd.pid'),
            ],
        )

    def test_nonASCIIErrorInParent(self):
        """
        When the child writes a non-ASCII error message to the status
        pipe during daemonization, the parent writes the repr of the
        message to C{stderr} and exits with a non-zero status code.
        """
        self.assertErrorInParentBehavior(
            readData=b"1 Exception: \xff",
            errorMessage=(
                "An error has occurred: b'Exception: \\xff'\n"
                "Please look at log file for more information.\n"
            ),
            mockOSActions=[
                ('chdir', '.'), ('umask', 0o077), ('fork', True),
                ('read', -1, 100), ('exit', 1), ('unlink', 'twistd.pid'),
            ],
        )


    def test_errorInParentWithTruncatedUnicode(self):
        """
        When the child writes a non-ASCII error message to the status
        pipe during daemonization, and that message is too longer, the
        parent writes the repr of the truncated message to C{stderr}
        and exits with a non-zero status code.
        """
        truncatedMessage = b'1 RuntimeError: ' + b'\\u2022' * 14
        # the escape sequence will appear to be escaped twice, because
        # we're getting the repr
        reportedMessage = "b'RuntimeError: {}'".format(r'\\u2022' * 14)
        self.assertErrorInParentBehavior(
            readData=truncatedMessage,
            errorMessage=(
                "An error has occurred: {}\n"
                "Please look at log file for more information.\n".format(
                    reportedMessage)
            ),
            mockOSActions=[
                ('chdir', '.'), ('umask', 0o077), ('fork', True),
                ('read', -1, 100), ('exit', 1), ('unlink', 'twistd.pid'),
            ],
        )


    def test_errorMessageTruncated(self):
        """
        If an error occurs during daemonization and its message is too
        long, it's truncated by the child.
        """
        self.assertErrorWritten(
            raised="x" * 200,
            reported=b'1 RuntimeError: ' + b'x' * 84)


    def test_unicodeErrorMessageTruncated(self):
        """
        If an error occurs during daemonization and its message is
        unicode and too long, it's truncated by the child, even if
        this splits a unicode escape sequence.
        """
        self.assertErrorWritten(
            raised=u"\u2022" * 30,
            reported=b'1 RuntimeError: ' + b'\\u2022' * 14,
        )


    def test_hooksCalled(self):
        """
        C{daemonize} indeed calls L{IReactorDaemonize.beforeDaemonize} and
        L{IReactorDaemonize.afterDaemonize} if the reactor implements
        L{IReactorDaemonize}.
        """
        reactor = FakeDaemonizingReactor()
        self.runner.daemonize(reactor)
        self.assertTrue(reactor._beforeDaemonizeCalled)
        self.assertTrue(reactor._afterDaemonizeCalled)


    def test_hooksNotCalled(self):
        """
        C{daemonize} does NOT call L{IReactorDaemonize.beforeDaemonize} or
        L{IReactorDaemonize.afterDaemonize} if the reactor does NOT implement
        L{IReactorDaemonize}.
        """
        reactor = FakeNonDaemonizingReactor()
        self.runner.daemonize(reactor)
        self.assertFalse(reactor._beforeDaemonizeCalled)
        self.assertFalse(reactor._afterDaemonizeCalled)



@implementer(_ISupportsExitSignalCapturing)
class SignalCapturingMemoryReactor(MemoryReactor):
    """
    MemoryReactor that implements the _ISupportsExitSignalCapturing interface,
    all other operations identical to MemoryReactor.
    """



class StubApplicationRunnerWithSignal(twistd._SomeApplicationRunner):
    """
    An application runner that uses a SignalCapturingMemoryReactor and
    has a _signalValue attribute that it will set in the reactor.

    @ivar _signalValue: The signal value to set on the reactor's _exitSignal
        attribute.
    """
    loggerFactory = CrippledAppLogger

    def __init__(self, config):
        super(StubApplicationRunnerWithSignal, self).__init__(config)
        self._signalValue = None


    def preApplication(self):
        """
        Does nothing.
        """

    def postApplication(self):
        """
        Instantiate a SignalCapturingMemoryReactor and start it
        in the runner.
        """
        reactor = SignalCapturingMemoryReactor()
        reactor._exitSignal = self._signalValue
        self.startReactor(reactor, sys.stdout, sys.stderr)



def stubApplicationRunnerFactoryCreator(signum):
    """
    Create a factory function to instantiate a
    StubApplicationRunnerWithSignal that will report signum as the captured
    signal..

    @param signum: The integer signal number or None
    @type signum: C{int} or C{None}

    @return: A factory function to create stub runners.
    @rtype: stubApplicationRunnerFactory
    """

    def stubApplicationRunnerFactory(config):
        """
        Create a StubApplicationRunnerWithSignal using a reactor that
        implements _ISupportsExitSignalCapturing and whose _exitSignal
        attribute is set to signum.

        @param config: The runner configuration, platform dependent.
        @type config: L{twisted.scripts.twistd.ServerOptions}

        @return: A runner to use for the test.
        @rtype: twisted.test.test_twistd.StubApplicationRunnerWithSignal
        """
        runner = StubApplicationRunnerWithSignal(config)
        runner._signalValue = signum
        return runner

    return stubApplicationRunnerFactory



class ExitWithSignalTests(unittest.TestCase):

    """
    Tests for L{twisted.application.app._exitWithSignal}.
    """

    def setUp(self):
        """
        Set up the server options and a fake for use by test cases.
        """
        self.config = twistd.ServerOptions()
        self.config.loadedPlugins = {'test_command': MockServiceMaker()}
        self.config.subOptions = object()
        self.config.subCommand = 'test_command'
        self.fakeKillArgs = [None, None]

        def fakeKill(pid, sig):
            """
            Fake method to capture arguments passed to os.kill.

            @param pid: The pid of the process being killed.

            @param sig: The signal sent to the process.
            """
            self.fakeKillArgs[0] = pid
            self.fakeKillArgs[1] = sig

        self.patch(os, 'kill', fakeKill)


    def test_exitWithSignal(self):
        """
        exitWithSignal replaces the existing signal handler with the default
        handler and sends the replaced signal to the current process.
        """

        fakeSignalArgs = [None, None]

        def fake_signal(sig, handler):
            fakeSignalArgs[0] = sig
            fakeSignalArgs[1] = handler

        self.patch(signal, 'signal', fake_signal)
        app._exitWithSignal(signal.SIGINT)

        self.assertEquals(fakeSignalArgs[0], signal.SIGINT)
        self.assertEquals(fakeSignalArgs[1], signal.SIG_DFL)
        self.assertEquals(self.fakeKillArgs[0], os.getpid())
        self.assertEquals(self.fakeKillArgs[1], signal.SIGINT)


    def test_normalExit(self):
        """
        _exitWithSignal is not called if the runner does not exit with a
        signal.
        """
        self.patch(
            twistd,
            '_SomeApplicationRunner',
            stubApplicationRunnerFactoryCreator(None)
        )
        twistd.runApp(self.config)
        self.assertIsNone(self.fakeKillArgs[0])
        self.assertIsNone(self.fakeKillArgs[1])


    def test_runnerExitsWithSignal(self):
        """
        _exitWithSignal is called when the runner exits with a signal.
        """
        self.patch(
            twistd,
            '_SomeApplicationRunner',
            stubApplicationRunnerFactoryCreator(signal.SIGINT)
        )
        twistd.runApp(self.config)
        self.assertEquals(self.fakeKillArgs[0], os.getpid())
        self.assertEquals(self.fakeKillArgs[1], signal.SIGINT)



if _twistd_unix is None:
    DaemonizeTests.skip = "twistd unix support not available"