~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2006, 2007, 2009 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Blackbox tests for debugger breakin"""

try:

    import ctypes

    have_ctypes = True

except ImportError:

    have_ctypes = False

import errno

import os

import signal

import subprocess

import sys

import time

from bzrlib import (

    breakin,

    errors,

    tests,

    )

class TestBreakin(tests.TestCase):

    # FIXME: If something is broken, these tests may just hang indefinitely in

    # wait() waiting for the child to exit when it's not going to.

    def setUp(self):

        super(TestBreakin, self).setUp()

        if breakin.determine_signal() is None:

            raise tests.TestSkipped('this platform is missing SIGQUIT'

                                    ' or SIGBREAK')

        if sys.platform == 'win32':

            # Windows doesn't have os.kill, and we catch the SIGBREAK signal.

            # We trigger SIGBREAK via a Console api so we need ctypes to access

            # the function

            if not have_ctypes:

                raise tests.UnavailableFeature('ctypes')

            self._send_signal = self._send_signal_win32

        else:

            self._send_signal = self._send_signal_via_kill

    def _send_signal_via_kill(self, pid, sig_type):

        if sig_type == 'break':

            sig_num = signal.SIGQUIT

        elif sig_type == 'kill':

            sig_num = signal.SIGKILL

        else:

            raise ValueError("unknown signal type: %s" % (sig_type,))

        os.kill(pid, sig_num)

    def _send_signal_win32(self, pid, sig_type):

        """Send a 'signal' on Windows.

        Windows doesn't really have signals in the same way. All it really

        supports is:

            1) Sending SIGINT to the *current* process group (so self, and all

                children of self)

            2) Sending SIGBREAK to a process that shares the current console,

                which can be in its own process group.

        So we have start_bzr_subprocess create a new process group for the

        spawned process (via a flag to Popen), and then we map

            SIGQUIT to GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT)

            SIGKILL to TerminateProcess

        """

        if sig_type == 'break':

            CTRL_BREAK_EVENT = 1

            # CTRL_C_EVENT = 0

            ret = ctypes.windll.kernel32.GenerateConsoleCtrlEvent(

                    CTRL_BREAK_EVENT, pid)

            if ret == 0: #error

                err = ctypes.FormatError()

                raise RuntimeError('failed to send CTRL_BREAK: %s'

                                   % (err,))

        elif sig_type == 'kill':

            # Does the exit code matter? For now we are just setting it to

            # something other than 0

            exit_code = breakin.determine_signal()

            ctypes.windll.kernel32.TerminateProcess(pid, exit_code)

    def _popen(self, *args, **kwargs):

        if sys.platform == 'win32':

            CREATE_NEW_PROCESS_GROUP = 512

            # This allows us to send a signal to the child, *without* also

            # sending it to ourselves

            kwargs['creationflags'] = CREATE_NEW_PROCESS_GROUP

        return super(TestBreakin, self)._popen(*args, **kwargs)

    def _dont_SIGQUIT_on_darwin(self):

        if sys.platform == 'darwin':

            # At least on Leopard and with python 2.6, this test will raise a

            # popup window asking if the python failure should be reported to

            # Apple... That's not the point of the test :) Marking the test as

            # not applicable Until we find a way to disable that intrusive

            # behavior... --vila20080611

            raise tests.TestNotApplicable(

                '%s raises a popup on OSX' % self.id())

    def _wait_for_process(self, pid, sig=None):

        # We don't know quite how long waiting for the process 'pid' will take,

        # but if it's more than 10s then it's probably not going to work.

        for i in range(100):

            time.sleep(0.1)

            if sig is not None:

                self._send_signal(pid, sig)

            # Use WNOHANG to ensure we don't get blocked, doing so, we may

            # leave the process continue after *we* die...

            # Win32 doesn't support WNOHANG, so we just pass 0

            opts = getattr(os, 'WNOHANG', 0)

            try:

                # TODO: waitpid doesn't work well on windows, we might consider

                #       using WaitForSingleObject(proc._handle, TIMEOUT)

                #       instead. Most notably, the WNOHANG isn't allowed, so

                #       this can hang indefinitely.

                pid_killed, returncode = os.waitpid(pid, opts)

                if (pid_killed, returncode) != (0, 0):

                    if sig is not None:

                        # high bit in low byte says if core was dumped; we

                        # don't care

                        status, sig = (returncode >> 8, returncode & 0x7f)

                        return True, sig

            except OSError, e:

                if e.errno in (errno.ECHILD, errno.ESRCH):

                    # The process doesn't exist anymore

                    return True, None

                else:

                    raise

        return False, None

    # port 0 means to allocate any port

    _test_process_args = ['serve', '--port', 'localhost:0']

    def test_breakin(self):

        # Break in to a debugger while bzr is running

        # we need to test against a command that will wait for

        # a while -- bzr serve should do

        proc = self.start_bzr_subprocess(self._test_process_args,

                env_changes=dict(BZR_SIGQUIT_PDB=None))

        # wait for it to get started, and print the 'listening' line

        proc.stderr.readline()

        # first sigquit pops into debugger

        self._send_signal(proc.pid, 'break')

        # Wait for the debugger to acknowledge the signal reception

        # Note that it is possible for this to deadlock if the child doesn't

        # acknowlege the signal and write to stderr. Perhaps we should try

        # os.read(proc.stderr.fileno())?

        err = proc.stderr.readline()

        self.assertContainsRe(err, r'entering debugger')

        # Now that the debugger is entered, we can ask him to quit

        proc.stdin.write("q\n")

        # We wait a bit to let the child process handles our query and avoid

        # triggering deadlocks leading to hangs on multi-core hosts...

        dead, sig = self._wait_for_process(proc.pid)

        if not dead:

            # The process didn't finish, let's kill it before reporting failure

            dead, sig = self._wait_for_process(proc.pid, 'kill')

            if dead:

                raise tests.KnownFailure(

                    "subprocess wasn't terminated, it had to be killed")

            else:

                self.fail("subprocess %d wasn't terminated by repeated SIGKILL",

                          proc.pid)

    def test_breakin_harder(self):

        """SIGQUITting twice ends the process."""

        self._dont_SIGQUIT_on_darwin()

        proc = self.start_bzr_subprocess(self._test_process_args,

                env_changes=dict(BZR_SIGQUIT_PDB=None))

        # wait for it to get started, and print the 'listening' line

        proc.stderr.readline()

        # break into the debugger

        self._send_signal(proc.pid, 'break')

        # Wait for the debugger to acknowledge the signal reception (since we

        # want to send a second signal, we ensure it doesn't get lost by

        # validating the first get received and produce its effect).

        err = proc.stderr.readline()

        self.assertContainsRe(err, r'entering debugger')

        dead, sig = self._wait_for_process(proc.pid, 'break')

        self.assertTrue(dead)

        # Either the child was dead before we could read its status, or the

        # child was dead from the signal we sent it.

        self.assertTrue(sig in (None, breakin.determine_signal()))

    def test_breakin_disabled(self):

        self._dont_SIGQUIT_on_darwin()

        proc = self.start_bzr_subprocess(self._test_process_args,

                env_changes=dict(BZR_SIGQUIT_PDB='0'))

        # wait for it to get started, and print the 'listening' line

        proc.stderr.readline()

        # first hit should just kill it

        self._send_signal(proc.pid, 'break')

        proc.wait()