~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2007 Canonical Ltd

#   Authors: Robert Collins <robert.collins@canonical.com>

#

# 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Support for running strace against the current process."""

import os

import signal

import subprocess

import tempfile

# this is currently test-focused, so importing bzrlib.tests is ok. We might

# want to move feature to its own module though.

from bzrlib.tests import Feature

def strace(function, *args, **kwargs):

    """Invoke strace on function.

    :return: a tuple: function-result, a StraceResult.

    """

    # capture strace output to a file

    log_file = tempfile.TemporaryFile()

    log_file_fd = log_file.fileno()

    pid = os.getpid()

    # start strace

    proc = subprocess.Popen(['strace',

        '-f', '-r', '-tt', '-p', str(pid),

        ],

        stderr=log_file_fd,

        stdout=log_file_fd)

    # TODO? confirm its started (test suite should be sufficient)

    # (can loop on proc.pid, but that may not indicate started and attached.)

    result = function(*args, **kwargs)

    # stop strace

    os.kill(proc.pid, signal.SIGQUIT)

    proc.communicate()

    # grab the log

    log_file.seek(0)

    log = log_file.read()

    log_file.close()

    return result, StraceResult(log)

class StraceResult(object):

    """The result of stracing a function."""

    def __init__(self, raw_log):

        """Create a StraceResult.

        :param raw_log: The output that strace created.

        """

        self.raw_log = raw_log

class _StraceFeature(Feature):

    def _probe(self):

        try:

            proc = subprocess.Popen(['strace'],

                stderr=subprocess.PIPE,

                stdout=subprocess.PIPE)

            proc.communicate()

            return True

        except OSError, e:

            if e.errno == errno.ENOENT:

                # strace is not installed

                return False

            else:

                raise

    def feature_name(self):

        return 'strace'

StraceFeature = _StraceFeature()