Merge branch 'master' of ssh://git.fedoraproject.org/git/hosted/func

9 files changed, 1875 insertions, 0 deletions

diff --git a/minion/AuthedXMLRPCServer.py b/minion/AuthedXMLRPCServer.py
new file mode 100644
index 0000000..490b57a
--- /dev/null
+++ b/minion/AuthedXMLRPCServer.py
@@ -0,0 +1,144 @@
+# 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 Library 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.
+#
+# Copyright 2005 Dan Williams <dcbw@redhat.com> and Red Hat, Inc.
+# Modifications by Seth Vidal - 2007
+
+import os, sys
+import socket
+import time
+import SocketServer
+import xmlrpclib
+import SimpleXMLRPCServer
+from func import SSLCommon
+import OpenSSL
+
+
+
+class AuthedSimpleXMLRPCRequestHandler(SimpleXMLRPCServer.SimpleXMLRPCRequestHandler):
+
+    # For some reason, httplib closes the connection right after headers
+    # have been sent if the connection is _not_ HTTP/1.1, which results in
+    # a "Bad file descriptor" error when the client tries to read from the socket
+    protocol_version = "HTTP/1.1"
+
+    def setup(self):
+        """
+        We need to use socket._fileobject Because SSL.Connection
+        doesn't have a 'dup'. Not exactly sure WHY this is, but
+        this is backed up by comments in socket.py and SSL/connection.c
+        """
+        self.connection = self.request # for doPOST
+        self.rfile = socket._fileobject(self.request, "rb", self.rbufsize)
+        self.wfile = socket._fileobject(self.request, "wb", self.wbufsize)
+                                                                    
+    def do_POST(self):
+        self.server._this_request = (self.request, self.client_address)
+        try:
+            SimpleXMLRPCServer.SimpleXMLRPCRequestHandler.do_POST(self)
+        except socket.timeout:
+            pass
+        except (socket.error, OpenSSL.SSL.SysCallError), e:
+            print "Error (%s): socket error - '%s'" % (self.client_address, e)
+
+
+class BaseAuthedXMLRPCServer:
+    def __init__(self, address, authinfo_callback=None):
+        self.allow_reuse_address = 1
+        self.logRequests = 1
+        self.authinfo_callback = authinfo_callback
+
+        self.funcs = {}
+        self.instance = None
+
+    def get_authinfo(self, request, client_address):
+        print 'down here'
+        if self.authinfo_callback:
+            return self.authinfo_callback(request, client_address)
+        return None
+
+
+class AuthedSSLXMLRPCServer(BaseAuthedXMLRPCServer, SSLCommon.BaseSSLServer, SimpleXMLRPCServer.SimpleXMLRPCServer):
+    """ Extension to allow more fine-tuned SSL handling """
+
+    def __init__(self, address, pkey, cert, ca_cert, authinfo_callback=None, timeout=None):
+        BaseAuthedXMLRPCServer.__init__(self, address, authinfo_callback)
+        SimpleXMLRPCServer.SimpleXMLRPCServer.__init__(self, address, AuthedSimpleXMLRPCRequestHandler)
+        SSLCommon.BaseSSLServer.__init__(self, address, AuthedSimpleXMLRPCRequestHandler, pkey, cert, ca_cert, timeout=timeout)
+
+
+
+class AuthedXMLRPCServer(BaseAuthedXMLRPCServer, SSLCommon.BaseServer, SimpleXMLRPCServer.SimpleXMLRPCServer):
+
+    def __init__(self, address, authinfo_callback=None):
+        BaseAuthedXMLRPCServer.__init__(self, address, authinfo_callback)
+        SSLCommon.BaseServer.__init__(self, address, AuthedSimpleXMLRPCRequestHandler)
+
+
+###########################################################
+# Testing stuff
+###########################################################
+
+class ReqHandler:
+    def ping(self, callerid, trynum):
+        print 'clearly not'
+        print callerid
+        print trynum
+        return "pong %d / %d" % (callerid, trynum)
+
+class TestServer(AuthedSSLXMLRPCServer):
+    """
+    SSL XMLRPC server that authenticates clients based on their certificate.
+    """
+
+    def __init__(self, address, pkey, cert, ca_cert):
+        AuthedSSLXMLRPCServer.__init__(self, address, pkey, cert, ca_cert, self.auth_cb)
+    
+    def _dispatch(self, method, params):
+        if method == 'trait_names' or method == '_getAttributeNames':
+            return dir(self)
+        # if we have _this_request then we get the peer cert from it
+        # handling all the authZ checks in _dispatch() means we don't even call the method
+        # for whatever it wants to do and we have the method name.
+
+        if hasattr(self, '_this_request'):
+            r,a = self._this_request
+            p = r.get_peer_certificate()
+            print dir(p)
+            print p.get_subject()
+        else:
+            print 'no cert'    
+
+        return "your mom"
+                 
+    def auth_cb(self, request, client_address):
+        peer_cert = request.get_peer_certificate()
+        return peer_cert.get_subject().CN
+
+
+if __name__ == '__main__':
+    if len(sys.argv) < 4:
+        print "Usage: python AuthdXMLRPCServer.py key cert ca_cert"
+        sys.exit(1)
+
+    pkey = sys.argv[1]
+    cert = sys.argv[2]
+    ca_cert = sys.argv[3]
+
+    print "Starting the server."
+    server = TestServer(('localhost', 51234), pkey, cert, ca_cert)
+    h = ReqHandler()
+    server.register_instance(h)
+    server.serve_forever()
+
diff --git a/minion/__init__.py b/minion/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/minion/__init__.py
diff --git a/minion/codes.py b/minion/codes.py
new file mode 100755
index 0000000..c549709
--- /dev/null
+++ b/minion/codes.py
@@ -0,0 +1,25 @@
+#!/usr/bin/python
+"""
+func
+
+Copyright 2007, Red Hat, Inc
+See AUTHORS
+
+This software may be freely redistributed under the terms of the GNU
+general public license.
+
+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., 675 Mass Ave, Cambridge, MA 02139, USA.
+"""
+
+import exceptions
+
+
+class FuncException(exceptions.Exception):
+   pass
+
+class InvalidMethodException(FuncException):
+   pass
+
+# FIXME: more sub-exceptions maybe
diff --git a/minion/config_data.py b/minion/config_data.py
new file mode 100755
index 0000000..021a52d
--- /dev/null
+++ b/minion/config_data.py
@@ -0,0 +1,51 @@
+#!/usr/bin/python
+
+# func
+#
+# Copyright 2006, Red Hat, Inc
+# see AUTHORS
+#
+# This software may be freely redistributed under the terms of the GNU
+# general public license.
+
+# 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+import codes
+
+import os
+import ConfigParser
+
+CONFIG_FILE = "/etc/func/settings"
+
+class Config:
+
+    # this class is a Borg
+    __shared_state = {}
+    has_read = False
+
+    def __init__(self):
+        self.__dict__ = self.__shared_state
+        self.ds = {}
+        if not self.has_read:
+            self.read()
+            Config.has_read = True
+
+    def read(self):
+
+        if not os.path.exists(CONFIG_FILE):
+            raise codes.FuncException("Missing %s" % CONFIG_FILE)
+
+        cp = ConfigParser.ConfigParser()
+
+        cp.read([CONFIG_FILE])
+        
+        self.ds["is_overlord"] = int(cp.get("general","is_overlord"))
+        self.ds["is_minion"] = int(cp.get("general","is_minion"))
+        self.ds["overlord_server"] = cp.get("general","overlord_server")
+
+    def get(self):
+        return self.ds
+
+
diff --git a/minion/logger.py b/minion/logger.py
new file mode 100755
index 0000000..1e60dc0
--- /dev/null
+++ b/minion/logger.py
@@ -0,0 +1,72 @@
+#!/usr/bin/python
+
+## func
+##
+## Copyright 2007, Red Hat, Inc
+## See AUTHORS
+##
+## This software may be freely redistributed under the terms of the GNU
+## general public license.
+##
+## 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+##
+##
+
+
+import logging
+import config_data
+
+
+# from the comments in http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531
+class Singleton(object):
+    def __new__(type, *args, **kwargs):
+        if not '_the_instance' in type.__dict__:
+            type._the_instance = object.__new__(type, *args, **kwargs)
+        return type._the_instance
+
+# logging is weird, we don't want to setup multiple handlers
+# so make sure we do that mess only once
+
+class Logger(Singleton):
+    _no_handlers = True
+
+    def __init__(self, logfilepath ="/var/log/func/func.log"):
+
+        self.config = config_data.Config().get()     
+        if self.config.has_key("log_level"):
+           self.loglevel = logging._levelNames[self.config["log_level"]]
+        else:
+           self.loglevel = logging.INFO   
+        self._setup_logging()
+        if self._no_handlers:
+            self._setup_handlers(logfilepath=logfilepath)
+        
+    def _setup_logging(self):
+        self.logger = logging.getLogger("svc")
+
+    def _setup_handlers(self, logfilepath="/var/log/func/func.log"):
+        handler = logging.FileHandler(logfilepath, "a")
+        self.logger.setLevel(self.loglevel)
+        formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s")
+        handler.setFormatter(formatter)
+        self.logger.addHandler(handler)
+        self._no_handlers = False
+
+
+class AuditLogger(Logger):
+    def __init__(self, logfilepath = "/var/log/func/audit.log"):
+        self.loglevel = logging.INFO
+        self._setup_logging()
+        if self._no_handlers:
+             self._setup_handlers(logfilepath=logfilepath)
+
+    def log_call(self, method, params):
+        # square away a good parseable format at some point -akl
+        self.logger.info("%s called with %s" % (method, params))
+
+
+
+
+        
diff --git a/minion/module_loader.py b/minion/module_loader.py
new file mode 100755
index 0000000..7cfcd26
--- /dev/null
+++ b/minion/module_loader.py
@@ -0,0 +1,103 @@
+#!/usr/bin/python
+
+## func
+##
+## Copyright 2007, Red Hat, Inc
+## See AUTHORS
+##
+## This software may be freely redistributed under the terms of the GNU
+## general public license.
+##
+## 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+##
+##
+
+
+import distutils.sysconfig
+import os
+import sys
+from rhpl.translate import _
+
+
+def module_walker(topdir):
+    module_files = []
+    for root, dirs, files in os.walk(topdir):
+        # we should get here for each subdir
+        for filename in files:
+            # ASSUMPTION: all module files will end with .py, .pyc, .pyo
+            if filename[-3:] == ".py" or filename[-4:] == ".pyc" or filename[-4:] == ".pyo":
+                # we don't really care about __init__ files, though we do requure them
+                if filename[:8] == "__init__":
+                    continue
+                # the normpath is important, since we (since we what?! -RN)
+                module_files.append(os.path.normpath("%s/%s" % (root, filename)))
+
+                
+    return module_files
+
+def load_modules(blacklist=None):
+
+    module_file_path="%s/func/minion/modules/" % distutils.sysconfig.get_python_lib()
+    mod_path="%s/func/minion/"  % distutils.sysconfig.get_python_lib()
+
+    sys.path.insert(0, mod_path)
+    mods = {}
+
+    filenames = module_walker(module_file_path)
+
+    # FIXME: this is probably more complicated than it needs to be -akl
+    for fn in filenames:
+        # aka, everything after the module_file_path
+        module_name_part = fn[len(module_file_path):]
+        dirname, basename = os.path.split(module_name_part)
+
+        if basename == "__init__.py":
+            continue
+        if basename[-3:] == ".py":
+            modname = basename[:-3]
+        elif basename[-4:] in [".pyc", ".pyo"]:
+            modname = basename[:-4]
+
+        pathname = modname
+        if dirname != "":
+            pathname = "%s/%s" % (dirname, modname)
+
+        mod_imp_name = pathname.replace("/", ".")
+
+        if mods.has_key(mod_imp_name):
+            # If we've already imported mod_imp_name, don't import it again
+            continue
+
+        try:
+            blip =  __import__("modules.%s" % ( mod_imp_name), globals(), locals(), [mod_imp_name])
+            if not hasattr(blip, "register_rpc"):
+		errmsg = _("%(module_path)s%(modname)s module not a proper module")
+                print errmsg % {'module_path': module_file_path, 'modname':mod_imp_name} 
+                continue
+            mods[mod_imp_name] = blip
+        except ImportError, e:
+            # A module that raises an ImportError is (for now) simply not loaded.
+            errmsg = _("Could not load %s module: %s")
+            print errmsg % (mod_imp_name, e)
+
+            continue
+
+    return mods
+
+
+if __name__ == "__main__":
+
+    module_file_path = "/usr/lib/python2.5/site-packages/func/minion/modules/"
+    bar = module_walker(module_file_path)
+    print bar
+    for f in bar:
+        print f
+        print os.path.basename(f)
+        print os.path.split(f)
+        g = f[len(module_file_path):]
+        print g
+        print os.path.split(g)
+
+    print load_modules()
diff --git a/minion/server.py b/minion/server.py
new file mode 100755
index 0000000..cd3c9e7
--- /dev/null
+++ b/minion/server.py
@@ -0,0 +1,216 @@
+#!/usr/bin/python
+
+"""
+func
+
+Copyright 2007, Red Hat, Inc
+see AUTHORS
+
+This software may be freely redistributed under the terms of the GNU
+general public license.
+
+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., 675 Mass Ave, Cambridge, MA 02139, USA.
+"""
+
+# standard modules
+import SimpleXMLRPCServer
+import string
+import sys
+import traceback
+
+from rhpl.translate import _, N_, textdomain, utf8
+I18N_DOMAIN = "func"
+
+# our modules
+import codes
+import config_data
+import logger
+import module_loader
+import utils
+
+# ======================================================================================
+
+class XmlRpcInterface(object):
+
+    def __init__(self, modules={}, server=None):
+
+        """
+        Constructor.
+        """
+
+        config_obj = config_data.Config()
+        self.config = config_obj.get()
+        self.modules = modules
+        self.logger = logger.Logger().logger
+        self.audit_logger = logger.AuditLogger()
+        self.__setup_handlers()
+
+        # need a reference so we can log ip's, certs, etc
+        self.server = server
+        
+    def __setup_handlers(self):
+
+        """
+        Add RPC functions from each class to the global list so they can be called.
+        """
+
+        self.handlers = {}
+        for x in self.modules.keys():
+            try:
+                self.modules[x].register_rpc(self.handlers, x)
+                self.logger.debug("adding %s" % x)
+            except AttributeError, e:
+                self.logger.warning("module %s not loaded, missing register_rpc method" % self.modules[x])
+
+
+        # internal methods that we do instead of spreading internal goo
+        # all over the modules. For now, at lest -akl
+
+        self.handlers["system.listMethods"] = self.list_methods
+
+    
+    def list_methods(self):
+        return self.handlers.keys()
+
+
+
+    def get_dispatch_method(self, method):
+
+        if method in self.handlers:
+            return FuncApiMethod(self.logger, method, self.handlers[method])
+      
+        else:
+            self.logger.info("Unhandled method call for method: %s " % method)
+            raise codes.InvalidMethodException
+
+    def _dispatch(self, method, params):
+
+        """
+        the SimpleXMLRPCServer class will call _dispatch if it doesn't
+        find a handler method 
+        """
+
+        # Recognize ipython's tab completion calls
+        if method == 'trait_names' or method == '_getAttributeNames':
+            return self.handlers.keys()
+
+        # XXX FIXME - need to figure out how to dig into the server base classes
+        # so we can get client ip, and eventually cert id info -akl
+        self.audit_logger.log_call(method, params)
+
+        return self.get_dispatch_method(method)(*params)
+
+# ======================================================================================
+
+class FuncApiMethod:
+
+    """
+    Used to hold a reference to all of the registered functions.
+    """
+
+    def __init__(self, logger, name, method):
+
+        self.logger = logger
+        self.__method = method
+        self.__name = name
+        
+    def __log_exc(self):
+
+        """
+        Log an exception.
+        """
+
+        (t, v, tb) = sys.exc_info()
+        self.logger.info("Exception occured: %s" % t )
+        self.logger.info("Exception value: %s" % v)
+        self.logger.info("Exception Info:\n%s" % string.join(traceback.format_list(traceback.extract_tb(tb))))
+
+    def __call__(self, *args):
+
+        self.logger.debug("(X) -------------------------------------------")
+
+        try:
+            rc = self.__method(*args)
+        except codes.FuncException, e:
+            self.__log_exc()
+            rc = e
+        except:
+            self.logger.debug("Not a Func-specific exception")
+            self.__log_exc()
+            raise
+        self.logger.debug("Return code for %s: %s" % (self.__name, rc))
+
+        return rc
+
+# ======================================================================================
+
+def serve():
+
+     """
+     Code for starting the XMLRPC service. 
+     FIXME:  make this HTTPS (see RRS code) and make accompanying Rails changes..
+     """
+
+     modules = module_loader.load_modules()
+
+     server =FuncXMLRPCServer(('', 51234))
+     server.logRequests = 0 # don't print stuff to console
+
+     websvc = XmlRpcInterface(modules=modules,server=server)
+     
+     server.register_instance(websvc)
+     server.serve_forever()
+
+# ======================================================================================
+
+class FuncXMLRPCServer(SimpleXMLRPCServer.SimpleXMLRPCServer):
+
+    def __init__(self, args):
+
+       self.allow_reuse_address = True
+       SimpleXMLRPCServer.SimpleXMLRPCServer.__init__(self, args)
+
+# ======================================================================================
+      
+def main(argv):
+
+    """
+    Start things up.
+    """
+
+    modules = module_loader.load_modules()
+
+    print "\n\n\n\n\n"
+    print " WARNING WARNING WARNING"
+    print "DANGER DANGER DANGER"
+    print "\n\n\n\n"
+    print "THERE IS NO AUTHENTICATION IN THIS VERSION"
+    print "DO NOT RUN ON A MACHINE EXPOSED TO ANYONE YOU DO NOT TRUST"
+    print " THEY CAN DO VERY BAD THINGS"
+    print "\n\n\n\n\n"
+    print "Really, don't do that. It is not at all secure at the moment"
+    print "like, at all."
+    print ""
+    print "Seriously.\n\n"
+
+    try:
+        serve()
+    except codes.FuncException, e:
+        print >> sys.stderr, 'error: %s' % e
+        sys.exit(1)
+
+    if "daemon" in sys.argv or "--daemon" in sys.argv:
+        utils.daemonize("/var/run/vf_server.pid")
+    else:
+        print "serving...\n"
+
+       
+# ======================================================================================
+
+if __name__ == "__main__":
+    textdomain(I18N_DOMAIN)
+    main(sys.argv)
+
+
diff --git a/minion/sub_process.py b/minion/sub_process.py
new file mode 100644
index 0000000..7c229dc
--- /dev/null
+++ b/minion/sub_process.py
@@ -0,0 +1,1217 @@
+# subprocess - Subprocesses with accessible I/O streams
+#
+# For more information about this module, see PEP 324.
+#
+# This module should remain compatible with Python 2.2, see PEP 291.
+#
+# Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se>
+#
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/2.4/license for licensing details.
+
+r"""subprocess - Subprocesses with accessible I/O streams
+
+This module allows you to spawn processes, connect to their
+input/output/error pipes, and obtain their return codes.  This module
+intends to replace several other, older modules and functions, like:
+
+os.system
+os.spawn*
+os.popen*
+popen2.*
+commands.*
+
+Information about how the subprocess module can be used to replace these
+modules and functions can be found below.
+
+
+
+Using the subprocess module
+===========================
+This module defines one class called Popen:
+
+class Popen(args, bufsize=0, executable=None,
+            stdin=None, stdout=None, stderr=None,
+            preexec_fn=None, close_fds=False, shell=False,
+            cwd=None, env=None, universal_newlines=False,
+            startupinfo=None, creationflags=0):
+
+
+Arguments are:
+
+args should be a string, or a sequence of program arguments.  The
+program to execute is normally the first item in the args sequence or
+string, but can be explicitly set by using the executable argument.
+
+On UNIX, with shell=False (default): In this case, the Popen class
+uses os.execvp() to execute the child program.  args should normally
+be a sequence.  A string will be treated as a sequence with the string
+as the only item (the program to execute).
+
+On UNIX, with shell=True: If args is a string, it specifies the
+command string to execute through the shell.  If args is a sequence,
+the first item specifies the command string, and any additional items
+will be treated as additional shell arguments.
+
+On Windows: the Popen class uses CreateProcess() to execute the child
+program, which operates on strings.  If args is a sequence, it will be
+converted to a string using the list2cmdline method.  Please note that
+not all MS Windows applications interpret the command line the same
+way: The list2cmdline is designed for applications using the same
+rules as the MS C runtime.
+
+bufsize, if given, has the same meaning as the corresponding argument
+to the built-in open() function: 0 means unbuffered, 1 means line
+buffered, any other positive value means use a buffer of
+(approximately) that size.  A negative bufsize means to use the system
+default, which usually means fully buffered.  The default value for
+bufsize is 0 (unbuffered).
+
+stdin, stdout and stderr specify the executed programs' standard
+input, standard output and standard error file handles, respectively.
+Valid values are PIPE, an existing file descriptor (a positive
+integer), an existing file object, and None.  PIPE indicates that a
+new pipe to the child should be created.  With None, no redirection
+will occur; the child's file handles will be inherited from the
+parent.  Additionally, stderr can be STDOUT, which indicates that the
+stderr data from the applications should be captured into the same
+file handle as for stdout.
+
+If preexec_fn is set to a callable object, this object will be called
+in the child process just before the child is executed.
+
+If close_fds is true, all file descriptors except 0, 1 and 2 will be
+closed before the child process is executed.
+
+if shell is true, the specified command will be executed through the
+shell.
+
+If cwd is not None, the current directory will be changed to cwd
+before the child is executed.
+
+If env is not None, it defines the environment variables for the new
+process.
+
+If universal_newlines is true, the file objects stdout and stderr are
+opened as a text files, but lines may be terminated by any of '\n',
+the Unix end-of-line convention, '\r', the Macintosh convention or
+'\r\n', the Windows convention.  All of these external representations
+are seen as '\n' by the Python program.  Note: This feature is only
+available if Python is built with universal newline support (the
+default).  Also, the newlines attribute of the file objects stdout,
+stdin and stderr are not updated by the communicate() method.
+
+The startupinfo and creationflags, if given, will be passed to the
+underlying CreateProcess() function.  They can specify things such as
+appearance of the main window and priority for the new process.
+(Windows only)
+
+
+This module also defines two shortcut functions:
+
+call(*popenargs, **kwargs):
+    Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+
+check_call(*popenargs, **kwargs):
+    Run command with arguments.  Wait for command to complete.  If the
+    exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+
+Exceptions
+----------
+Exceptions raised in the child process, before the new program has
+started to execute, will be re-raised in the parent.  Additionally,
+the exception object will have one extra attribute called
+'child_traceback', which is a string containing traceback information
+from the childs point of view.
+
+The most common exception raised is OSError.  This occurs, for
+example, when trying to execute a non-existent file.  Applications
+should prepare for OSErrors.
+
+A ValueError will be raised if Popen is called with invalid arguments.
+
+check_call() will raise CalledProcessError, if the called process
+returns a non-zero return code.
+
+
+Security
+--------
+Unlike some other popen functions, this implementation will never call
+/bin/sh implicitly.  This means that all characters, including shell
+metacharacters, can safely be passed to child processes.
+
+
+Popen objects
+=============
+Instances of the Popen class have the following methods:
+
+poll()
+    Check if child process has terminated.  Returns returncode
+    attribute.
+
+wait()
+    Wait for child process to terminate.  Returns returncode attribute.
+
+communicate(input=None)
+    Interact with process: Send data to stdin.  Read data from stdout
+    and stderr, until end-of-file is reached.  Wait for process to
+    terminate.  The optional stdin argument should be a string to be
+    sent to the child process, or None, if no data should be sent to
+    the child.
+
+    communicate() returns a tuple (stdout, stderr).
+
+    Note: The data read is buffered in memory, so do not use this
+    method if the data size is large or unlimited.
+
+The following attributes are also available:
+
+stdin
+    If the stdin argument is PIPE, this attribute is a file object
+    that provides input to the child process.  Otherwise, it is None.
+
+stdout
+    If the stdout argument is PIPE, this attribute is a file object
+    that provides output from the child process.  Otherwise, it is
+    None.
+
+stderr
+    If the stderr argument is PIPE, this attribute is file object that
+    provides error output from the child process.  Otherwise, it is
+    None.
+
+pid
+    The process ID of the child process.
+
+returncode
+    The child return code.  A None value indicates that the process
+    hasn't terminated yet.  A negative value -N indicates that the
+    child was terminated by signal N (UNIX only).
+
+
+Replacing older functions with the subprocess module
+====================================================
+In this section, "a ==> b" means that b can be used as a replacement
+for a.
+
+Note: All functions in this section fail (more or less) silently if
+the executed program cannot be found; this module raises an OSError
+exception.
+
+In the following examples, we assume that the subprocess module is
+imported with "from subprocess import *".
+
+
+Replacing /bin/sh shell backquote
+---------------------------------
+output=`mycmd myarg`
+==>
+output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]
+
+
+Replacing shell pipe line
+-------------------------
+output=`dmesg | grep hda`
+==>
+p1 = Popen(["dmesg"], stdout=PIPE)
+p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
+output = p2.communicate()[0]
+
+
+Replacing os.system()
+---------------------
+sts = os.system("mycmd" + " myarg")
+==>
+p = Popen("mycmd" + " myarg", shell=True)
+pid, sts = os.waitpid(p.pid, 0)
+
+Note:
+
+* Calling the program through the shell is usually not required.
+
+* It's easier to look at the returncode attribute than the
+  exitstatus.
+
+A more real-world example would look like this:
+
+try:
+    retcode = call("mycmd" + " myarg", shell=True)
+    if retcode < 0:
+        print >>sys.stderr, "Child was terminated by signal", -retcode
+    else:
+        print >>sys.stderr, "Child returned", retcode
+except OSError, e:
+    print >>sys.stderr, "Execution failed:", e
+
+
+Replacing os.spawn*
+-------------------
+P_NOWAIT example:
+
+pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
+==>
+pid = Popen(["/bin/mycmd", "myarg"]).pid
+
+
+P_WAIT example:
+
+retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
+==>
+retcode = call(["/bin/mycmd", "myarg"])
+
+
+Vector example:
+
+os.spawnvp(os.P_NOWAIT, path, args)
+==>
+Popen([path] + args[1:])
+
+
+Environment example:
+
+os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
+==>
+Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
+
+
+Replacing os.popen*
+-------------------
+pipe = os.popen(cmd, mode='r', bufsize)
+==>
+pipe = Popen(cmd, shell=True, bufsize=bufsize, stdout=PIPE).stdout
+
+pipe = os.popen(cmd, mode='w', bufsize)
+==>
+pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin
+
+
+(child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdin, child_stdout) = (p.stdin, p.stdout)
+
+
+(child_stdin,
+ child_stdout,
+ child_stderr) = os.popen3(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
+(child_stdin,
+ child_stdout,
+ child_stderr) = (p.stdin, p.stdout, p.stderr)
+
+
+(child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
+(child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout)
+
+
+Replacing popen2.*
+------------------
+Note: If the cmd argument to popen2 functions is a string, the command
+is executed through /bin/sh.  If it is a list, the command is directly
+executed.
+
+(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
+==>
+p = Popen(["somestring"], shell=True, bufsize=bufsize
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdout, child_stdin) = (p.stdout, p.stdin)
+
+
+(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
+==>
+p = Popen(["mycmd", "myarg"], bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdout, child_stdin) = (p.stdout, p.stdin)
+
+The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
+except that:
+
+* subprocess.Popen raises an exception if the execution fails
+* the capturestderr argument is replaced with the stderr argument.
+* stdin=PIPE and stdout=PIPE must be specified.
+* popen2 closes all filedescriptors by default, but you have to specify
+  close_fds=True with subprocess.Popen.
+
+
+"""
+
+import sys
+mswindows = (sys.platform == "win32")
+
+import os
+import types
+import traceback
+
+# Exception classes used by this module.
+class CalledProcessError(Exception):
+    """This exception is raised when a process run by check_call() returns
+    a non-zero exit status.  The exit status will be stored in the
+    returncode attribute."""
+    def __init__(self, returncode, cmd):
+        self.returncode = returncode
+        self.cmd = cmd
+    def __str__(self):
+        return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+
+
+if mswindows:
+    import threading
+    import msvcrt
+    if 0: # <-- change this to use pywin32 instead of the _subprocess driver
+        import pywintypes
+        from win32api import GetStdHandle, STD_INPUT_HANDLE, \
+                             STD_OUTPUT_HANDLE, STD_ERROR_HANDLE
+        from win32api import GetCurrentProcess, DuplicateHandle, \
+                             GetModuleFileName, GetVersion
+        from win32con import DUPLICATE_SAME_ACCESS, SW_HIDE
+        from win32pipe import CreatePipe
+        from win32process import CreateProcess, STARTUPINFO, \
+                                 GetExitCodeProcess, STARTF_USESTDHANDLES, \
+                                 STARTF_USESHOWWINDOW, CREATE_NEW_CONSOLE
+        from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0
+    else:
+        from _subprocess import *
+        class STARTUPINFO:
+            dwFlags = 0
+            hStdInput = None
+            hStdOutput = None
+            hStdError = None
+            wShowWindow = 0
+        class pywintypes:
+            error = IOError
+else:
+    import select
+    import errno
+    import fcntl
+    import pickle
+
+__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"]
+
+try:
+    MAXFD = os.sysconf("SC_OPEN_MAX")
+except:
+    MAXFD = 256
+
+# True/False does not exist on 2.2.0
+try:
+    False
+except NameError:
+    False = 0
+    True = 1
+
+_active = []
+
+def _cleanup():
+    for inst in _active[:]:
+        if inst.poll(_deadstate=sys.maxint) >= 0:
+            try:
+                _active.remove(inst)
+            except ValueError:
+                # This can happen if two threads create a new Popen instance.
+                # It's harmless that it was already removed, so ignore.
+                pass
+
+PIPE = -1
+STDOUT = -2
+
+
+def call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+    """
+    return Popen(*popenargs, **kwargs).wait()
+
+
+def check_call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete.  If
+    the exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+    """
+    retcode = call(*popenargs, **kwargs)
+    cmd = kwargs.get("args")
+    if cmd is None:
+        cmd = popenargs[0]
+    if retcode:
+        raise CalledProcessError(retcode, cmd)
+    return retcode
+
+
+def list2cmdline(seq):
+    """
+    Translate a sequence of arguments into a command line
+    string, using the same rules as the MS C runtime:
+
+    1) Arguments are delimited by white space, which is either a
+       space or a tab.
+
+    2) A string surrounded by double quotation marks is
+       interpreted as a single argument, regardless of white space
+       contained within.  A quoted string can be embedded in an
+       argument.
+
+    3) A double quotation mark preceded by a backslash is
+       interpreted as a literal double quotation mark.
+
+    4) Backslashes are interpreted literally, unless they
+       immediately precede a double quotation mark.
+
+    5) If backslashes immediately precede a double quotation mark,
+       every pair of backslashes is interpreted as a literal
+       backslash.  If the number of backslashes is odd, the last
+       backslash escapes the next double quotation mark as
+       described in rule 3.
+    """
+
+    # See
+    # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
+    result = []
+    needquote = False
+    for arg in seq:
+        bs_buf = []
+
+        # Add a space to separate this argument from the others
+        if result:
+            result.append(' ')
+
+        needquote = (" " in arg) or ("\t" in arg)
+        if needquote:
+            result.append('"')
+
+        for c in arg:
+            if c == '\\':
+                # Don't know if we need to double yet.
+                bs_buf.append(c)
+            elif c == '"':
+                # Double backspaces.
+                result.append('\\' * len(bs_buf)*2)
+                bs_buf = []
+                result.append('\\"')
+            else:
+                # Normal char
+                if bs_buf:
+                    result.extend(bs_buf)
+                    bs_buf = []
+                result.append(c)
+
+        # Add remaining backspaces, if any.
+        if bs_buf:
+            result.extend(bs_buf)
+
+        if needquote:
+            result.extend(bs_buf)
+            result.append('"')
+
+    return ''.join(result)
+
+
+class Popen(object):
+    def __init__(self, args, bufsize=0, executable=None,
+                 stdin=None, stdout=None, stderr=None,
+                 preexec_fn=None, close_fds=False, shell=False,
+                 cwd=None, env=None, universal_newlines=False,
+                 startupinfo=None, creationflags=0):
+        """Create new Popen instance."""
+        _cleanup()
+
+        self._child_created = False
+        if not isinstance(bufsize, (int, long)):
+            raise TypeError("bufsize must be an integer")
+
+        if mswindows:
+            if preexec_fn is not None:
+                raise ValueError("preexec_fn is not supported on Windows "
+                                 "platforms")
+            if close_fds:
+                raise ValueError("close_fds is not supported on Windows "
+                                 "platforms")
+        else:
+            # POSIX
+            if startupinfo is not None:
+                raise ValueError("startupinfo is only supported on Windows "
+                                 "platforms")
+            if creationflags != 0:
+                raise ValueError("creationflags is only supported on Windows "
+                                 "platforms")
+
+        self.stdin = None
+        self.stdout = None
+        self.stderr = None
+        self.pid = None
+        self.returncode = None
+        self.universal_newlines = universal_newlines
+
+        # Input and output objects. The general principle is like
+        # this:
+        #
+        # Parent                   Child
+        # ------                   -----
+        # p2cwrite   ---stdin--->  p2cread
+        # c2pread    <--stdout---  c2pwrite
+        # errread    <--stderr---  errwrite
+        #
+        # On POSIX, the child objects are file descriptors.  On
+        # Windows, these are Windows file handles.  The parent objects
+        # are file descriptors on both platforms.  The parent objects
+        # are None when not using PIPEs. The child objects are None
+        # when not redirecting.
+
+        (p2cread, p2cwrite,
+         c2pread, c2pwrite,
+         errread, errwrite) = self._get_handles(stdin, stdout, stderr)
+
+        self._execute_child(args, executable, preexec_fn, close_fds,
+                            cwd, env, universal_newlines,
+                            startupinfo, creationflags, shell,
+                            p2cread, p2cwrite,
+                            c2pread, c2pwrite,
+                            errread, errwrite)
+
+        if p2cwrite:
+            self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
+        if c2pread:
+            if universal_newlines:
+                self.stdout = os.fdopen(c2pread, 'rU', bufsize)
+            else:
+                self.stdout = os.fdopen(c2pread, 'rb', bufsize)
+        if errread:
+            if universal_newlines:
+                self.stderr = os.fdopen(errread, 'rU', bufsize)
+            else:
+                self.stderr = os.fdopen(errread, 'rb', bufsize)
+
+
+    def _translate_newlines(self, data):
+        data = data.replace("\r\n", "\n")
+        data = data.replace("\r", "\n")
+        return data
+
+
+    def __del__(self):
+        if not self._child_created:
+            # We didn't get to successfully create a child process.
+            return
+        # In case the child hasn't been waited on, check if it's done.
+        self.poll(_deadstate=sys.maxint)
+        if self.returncode is None and _active is not None:
+            # Child is still running, keep us alive until we can wait on it.
+            _active.append(self)
+
+
+    def communicate(self, input=None):
+        """Interact with process: Send data to stdin.  Read data from
+        stdout and stderr, until end-of-file is reached.  Wait for
+        process to terminate.  The optional input argument should be a
+        string to be sent to the child process, or None, if no data
+        should be sent to the child.
+
+        communicate() returns a tuple (stdout, stderr)."""
+
+        # Optimization: If we are only using one pipe, or no pipe at
+        # all, using select() or threads is unnecessary.
+        if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
+            stdout = None
+            stderr = None
+            if self.stdin:
+                if input:
+                    self.stdin.write(input)
+                self.stdin.close()
+            elif self.stdout:
+                stdout = self.stdout.read()
+            elif self.stderr:
+                stderr = self.stderr.read()
+            self.wait()
+            return (stdout, stderr)
+
+        return self._communicate(input)
+
+
+    if mswindows:
+        #
+        # Windows methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tupel with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            if stdin is None and stdout is None and stderr is None:
+                return (None, None, None, None, None, None)
+
+            p2cread, p2cwrite = None, None
+            c2pread, c2pwrite = None, None
+            errread, errwrite = None, None
+
+            if stdin is None:
+                p2cread = GetStdHandle(STD_INPUT_HANDLE)
+            elif stdin == PIPE:
+                p2cread, p2cwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                p2cwrite = p2cwrite.Detach()
+                p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0)
+            elif isinstance(stdin, int):
+                p2cread = msvcrt.get_osfhandle(stdin)
+            else:
+                # Assuming file-like object
+                p2cread = msvcrt.get_osfhandle(stdin.fileno())
+            p2cread = self._make_inheritable(p2cread)
+
+            if stdout is None:
+                c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE)
+            elif stdout == PIPE:
+                c2pread, c2pwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                c2pread = c2pread.Detach()
+                c2pread = msvcrt.open_osfhandle(c2pread, 0)
+            elif isinstance(stdout, int):
+                c2pwrite = msvcrt.get_osfhandle(stdout)
+            else:
+                # Assuming file-like object
+                c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
+            c2pwrite = self._make_inheritable(c2pwrite)
+
+            if stderr is None:
+                errwrite = GetStdHandle(STD_ERROR_HANDLE)
+            elif stderr == PIPE:
+                errread, errwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                errread = errread.Detach()
+                errread = msvcrt.open_osfhandle(errread, 0)
+            elif stderr == STDOUT:
+                errwrite = c2pwrite
+            elif isinstance(stderr, int):
+                errwrite = msvcrt.get_osfhandle(stderr)
+            else:
+                # Assuming file-like object
+                errwrite = msvcrt.get_osfhandle(stderr.fileno())
+            errwrite = self._make_inheritable(errwrite)
+
+            return (p2cread, p2cwrite,
+                    c2pread, c2pwrite,
+                    errread, errwrite)
+
+
+        def _make_inheritable(self, handle):
+            """Return a duplicate of handle, which is inheritable"""
+            return DuplicateHandle(GetCurrentProcess(), handle,
+                                   GetCurrentProcess(), 0, 1,
+                                   DUPLICATE_SAME_ACCESS)
+
+
+        def _find_w9xpopen(self):
+            """Find and return absolut path to w9xpopen.exe"""
+            w9xpopen = os.path.join(os.path.dirname(GetModuleFileName(0)),
+                                    "w9xpopen.exe")
+            if not os.path.exists(w9xpopen):
+                # Eeek - file-not-found - possibly an embedding
+                # situation - see if we can locate it in sys.exec_prefix
+                w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix),
+                                        "w9xpopen.exe")
+                if not os.path.exists(w9xpopen):
+                    raise RuntimeError("Cannot locate w9xpopen.exe, which is "
+                                       "needed for Popen to work with your "
+                                       "shell or platform.")
+            return w9xpopen
+
+
+        def _execute_child(self, args, executable, preexec_fn, close_fds,
+                           cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite):
+            """Execute program (MS Windows version)"""
+
+            if not isinstance(args, types.StringTypes):
+                args = list2cmdline(args)
+
+            # Process startup details
+            if startupinfo is None:
+                startupinfo = STARTUPINFO()
+            if None not in (p2cread, c2pwrite, errwrite):
+                startupinfo.dwFlags |= STARTF_USESTDHANDLES
+                startupinfo.hStdInput = p2cread
+                startupinfo.hStdOutput = c2pwrite
+                startupinfo.hStdError = errwrite
+
+            if shell:
+                startupinfo.dwFlags |= STARTF_USESHOWWINDOW
+                startupinfo.wShowWindow = SW_HIDE
+                comspec = os.environ.get("COMSPEC", "cmd.exe")
+                args = comspec + " /c " + args
+                if (GetVersion() >= 0x80000000L or
+                        os.path.basename(comspec).lower() == "command.com"):
+                    # Win9x, or using command.com on NT. We need to
+                    # use the w9xpopen intermediate program. For more
+                    # information, see KB Q150956
+                    # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
+                    w9xpopen = self._find_w9xpopen()
+                    args = '"%s" %s' % (w9xpopen, args)
+                    # Not passing CREATE_NEW_CONSOLE has been known to
+                    # cause random failures on win9x.  Specifically a
+                    # dialog: "Your program accessed mem currently in
+                    # use at xxx" and a hopeful warning about the
+                    # stability of your system.  Cost is Ctrl+C wont
+                    # kill children.
+                    creationflags |= CREATE_NEW_CONSOLE
+
+            # Start the process
+            try:
+                hp, ht, pid, tid = CreateProcess(executable, args,
+                                         # no special security
+                                         None, None,
+                                         # must inherit handles to pass std
+                                         # handles
+                                         1,
+                                         creationflags,
+                                         env,
+                                         cwd,
+                                         startupinfo)
+            except pywintypes.error, e:
+                # Translate pywintypes.error to WindowsError, which is
+                # a subclass of OSError.  FIXME: We should really
+                # translate errno using _sys_errlist (or simliar), but
+                # how can this be done from Python?
+                raise WindowsError(*e.args)
+
+            # Retain the process handle, but close the thread handle
+            self._child_created = True
+            self._handle = hp
+            self.pid = pid
+            ht.Close()
+
+            # Child is launched. Close the parent's copy of those pipe
+            # handles that only the child should have open.  You need
+            # to make sure that no handles to the write end of the
+            # output pipe are maintained in this process or else the
+            # pipe will not close when the child process exits and the
+            # ReadFile will hang.
+            if p2cread is not None:
+                p2cread.Close()
+            if c2pwrite is not None:
+                c2pwrite.Close()
+            if errwrite is not None:
+                errwrite.Close()
+
+
+        def poll(self, _deadstate=None):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0:
+                    self.returncode = GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                obj = WaitForSingleObject(self._handle, INFINITE)
+                self.returncode = GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def _readerthread(self, fh, buffer):
+            buffer.append(fh.read())
+
+
+        def _communicate(self, input):
+            stdout = None # Return
+            stderr = None # Return
+
+            if self.stdout:
+                stdout = []
+                stdout_thread = threading.Thread(target=self._readerthread,
+                                                 args=(self.stdout, stdout))
+                stdout_thread.setDaemon(True)
+                stdout_thread.start()
+            if self.stderr:
+                stderr = []
+                stderr_thread = threading.Thread(target=self._readerthread,
+                                                 args=(self.stderr, stderr))
+                stderr_thread.setDaemon(True)
+                stderr_thread.start()
+
+            if self.stdin:
+                if input is not None:
+                    self.stdin.write(input)
+                self.stdin.close()
+
+            if self.stdout:
+                stdout_thread.join()
+            if self.stderr:
+                stderr_thread.join()
+
+            # All data exchanged.  Translate lists into strings.
+            if stdout is not None:
+                stdout = stdout[0]
+            if stderr is not None:
+                stderr = stderr[0]
+
+            # Translate newlines, if requested.  We cannot let the file
+            # object do the translation: It is based on stdio, which is
+            # impossible to combine with select (unless forcing no
+            # buffering).
+            if self.universal_newlines and hasattr(file, 'newlines'):
+                if stdout:
+                    stdout = self._translate_newlines(stdout)
+                if stderr:
+                    stderr = self._translate_newlines(stderr)
+
+            self.wait()
+            return (stdout, stderr)
+
+    else:
+        #
+        # POSIX methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tupel with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            p2cread, p2cwrite = None, None
+            c2pread, c2pwrite = None, None
+            errread, errwrite = None, None
+
+            if stdin is None:
+                pass
+            elif stdin == PIPE:
+                p2cread, p2cwrite = os.pipe()
+            elif isinstance(stdin, int):
+                p2cread = stdin
+            else:
+                # Assuming file-like object
+                p2cread = stdin.fileno()
+
+            if stdout is None:
+                pass
+            elif stdout == PIPE:
+                c2pread, c2pwrite = os.pipe()
+            elif isinstance(stdout, int):
+                c2pwrite = stdout
+            else:
+                # Assuming file-like object
+                c2pwrite = stdout.fileno()
+
+            if stderr is None:
+                pass
+            elif stderr == PIPE:
+                errread, errwrite = os.pipe()
+            elif stderr == STDOUT:
+                errwrite = c2pwrite
+            elif isinstance(stderr, int):
+                errwrite = stderr
+            else:
+                # Assuming file-like object
+                errwrite = stderr.fileno()
+
+            return (p2cread, p2cwrite,
+                    c2pread, c2pwrite,
+                    errread, errwrite)
+
+
+        def _set_cloexec_flag(self, fd):
+            try:
+                cloexec_flag = fcntl.FD_CLOEXEC
+            except AttributeError:
+                cloexec_flag = 1
+
+            old = fcntl.fcntl(fd, fcntl.F_GETFD)
+            fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag)
+
+
+        def _close_fds(self, but):
+            for i in xrange(3, MAXFD):
+                if i == but:
+                    continue
+                try:
+                    os.close(i)
+                except:
+                    pass
+
+
+        def _execute_child(self, args, executable, preexec_fn, close_fds,
+                           cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite):
+            """Execute program (POSIX version)"""
+
+            if isinstance(args, types.StringTypes):
+                args = [args]
+
+            if shell:
+                args = ["/bin/sh", "-c"] + args
+
+            if executable is None:
+                executable = args[0]
+
+            # For transferring possible exec failure from child to parent
+            # The first char specifies the exception type: 0 means
+            # OSError, 1 means some other error.
+            errpipe_read, errpipe_write = os.pipe()
+            self._set_cloexec_flag(errpipe_write)
+
+            self.pid = os.fork()
+            self._child_created = True
+            if self.pid == 0:
+                # Child
+                try:
+                    # Close parent's pipe ends
+                    if p2cwrite:
+                        os.close(p2cwrite)
+                    if c2pread:
+                        os.close(c2pread)
+                    if errread:
+                        os.close(errread)
+                    os.close(errpipe_read)
+
+                    # Dup fds for child
+                    if p2cread:
+                        os.dup2(p2cread, 0)
+                    if c2pwrite:
+                        os.dup2(c2pwrite, 1)
+                    if errwrite:
+                        os.dup2(errwrite, 2)
+
+                    # Close pipe fds.  Make sure we don't close the same
+                    # fd more than once, or standard fds.
+                    for fd in set((p2cread, c2pwrite, errwrite))-set((0,1,2)):
+                        if fd: os.close(fd)
+
+                    # Close all other fds, if asked for
+                    if close_fds:
+                        self._close_fds(but=errpipe_write)
+
+                    if cwd is not None:
+                        os.chdir(cwd)
+
+                    if preexec_fn:
+                        apply(preexec_fn)
+
+                    if env is None:
+                        os.execvp(executable, args)
+                    else:
+                        os.execvpe(executable, args, env)
+
+                except:
+                    exc_type, exc_value, tb = sys.exc_info()
+                    # Save the traceback and attach it to the exception object
+                    exc_lines = traceback.format_exception(exc_type,
+                                                           exc_value,
+                                                           tb)
+                    exc_value.child_traceback = ''.join(exc_lines)
+                    os.write(errpipe_write, pickle.dumps(exc_value))
+
+                # This exitcode won't be reported to applications, so it
+                # really doesn't matter what we return.
+                os._exit(255)
+
+            # Parent
+            os.close(errpipe_write)
+            if p2cread and p2cwrite:
+                os.close(p2cread)
+            if c2pwrite and c2pread:
+                os.close(c2pwrite)
+            if errwrite and errread:
+                os.close(errwrite)
+
+            # Wait for exec to fail or succeed; possibly raising exception
+            data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB
+            os.close(errpipe_read)
+            if data != "":
+                os.waitpid(self.pid, 0)
+                child_exception = pickle.loads(data)
+                raise child_exception
+
+
+        def _handle_exitstatus(self, sts):
+            if os.WIFSIGNALED(sts):
+                self.returncode = -os.WTERMSIG(sts)
+            elif os.WIFEXITED(sts):
+                self.returncode = os.WEXITSTATUS(sts)
+            else:
+                # Should never happen
+                raise RuntimeError("Unknown child exit status!")
+
+
+        def poll(self, _deadstate=None):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                try:
+                    pid, sts = os.waitpid(self.pid, os.WNOHANG)
+                    if pid == self.pid:
+                        self._handle_exitstatus(sts)
+                except os.error:
+                    if _deadstate is not None:
+                        self.returncode = _deadstate
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                pid, sts = os.waitpid(self.pid, 0)
+                self._handle_exitstatus(sts)
+            return self.returncode
+
+
+        def _communicate(self, input):
+            read_set = []
+            write_set = []
+            stdout = None # Return
+            stderr = None # Return
+
+            if self.stdin:
+                # Flush stdio buffer.  This might block, if the user has
+                # been writing to .stdin in an uncontrolled fashion.
+                self.stdin.flush()
+                if input:
+                    write_set.append(self.stdin)
+                else:
+                    self.stdin.close()
+            if self.stdout:
+                read_set.append(self.stdout)
+                stdout = []
+            if self.stderr:
+                read_set.append(self.stderr)
+                stderr = []
+
+            while read_set or write_set:
+                rlist, wlist, xlist = select.select(read_set, write_set, [])
+
+                if self.stdin in wlist:
+                    # When select has indicated that the file is writable,
+                    # we can write up to PIPE_BUF bytes without risk
+                    # blocking.  POSIX defines PIPE_BUF >= 512
+                    bytes_written = os.write(self.stdin.fileno(), input[:512])
+                    input = input[bytes_written:]
+                    if not input:
+                        self.stdin.close()
+                        write_set.remove(self.stdin)
+
+                if self.stdout in rlist:
+                    data = os.read(self.stdout.fileno(), 1024)
+                    if data == "":
+                        self.stdout.close()
+                        read_set.remove(self.stdout)
+                    stdout.append(data)
+
+                if self.stderr in rlist:
+                    data = os.read(self.stderr.fileno(), 1024)
+                    if data == "":
+                        self.stderr.close()
+                        read_set.remove(self.stderr)
+                    stderr.append(data)
+
+            # All data exchanged.  Translate lists into strings.
+            if stdout is not None:
+                stdout = ''.join(stdout)
+            if stderr is not None:
+                stderr = ''.join(stderr)
+
+            # Translate newlines, if requested.  We cannot let the file
+            # object do the translation: It is based on stdio, which is
+            # impossible to combine with select (unless forcing no
+            # buffering).
+            if self.universal_newlines and hasattr(file, 'newlines'):
+                if stdout:
+                    stdout = self._translate_newlines(stdout)
+                if stderr:
+                    stderr = self._translate_newlines(stderr)
+
+            self.wait()
+            return (stdout, stderr)
+
+
+def _demo_posix():
+    #
+    # Example 1: Simple redirection: Get process list
+    #
+    plist = Popen(["ps"], stdout=PIPE).communicate()[0]
+    print "Process list:"
+    print plist
+
+    #
+    # Example 2: Change uid before executing child
+    #
+    if os.getuid() == 0:
+        p = Popen(["id"], preexec_fn=lambda: os.setuid(100))
+        p.wait()
+
+    #
+    # Example 3: Connecting several subprocesses
+    #
+    print "Looking for 'hda'..."
+    p1 = Popen(["dmesg"], stdout=PIPE)
+    p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
+    print repr(p2.communicate()[0])
+
+    #
+    # Example 4: Catch execution error
+    #
+    print
+    print "Trying a weird file..."
+    try:
+        print Popen(["/this/path/does/not/exist"]).communicate()
+    except OSError, e:
+        if e.errno == errno.ENOENT:
+            print "The file didn't exist.  I thought so..."
+            print "Child traceback:"
+            print e.child_traceback
+        else:
+            print "Error", e.errno
+    else:
+        print >>sys.stderr, "Gosh.  No error."
+
+
+def _demo_windows():
+    #
+    # Example 1: Connecting several subprocesses
+    #
+    print "Looking for 'PROMPT' in set output..."
+    p1 = Popen("set", stdout=PIPE, shell=True)
+    p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE)
+    print repr(p2.communicate()[0])
+
+    #
+    # Example 2: Simple execution of program
+    #
+    print "Executing calc..."
+    p = Popen("calc")
+    p.wait()
+
+
+if __name__ == "__main__":
+    if mswindows:
+        _demo_windows()
+    else:
+        _demo_posix()
diff --git a/minion/utils.py b/minion/utils.py
new file mode 100755
index 0000000..724c847
--- /dev/null
+++ b/minion/utils.py
@@ -0,0 +1,47 @@
+#!/usr/bin/python
+
+"""
+Copyright 2007, Red Hat, Inc
+see AUTHORS
+
+This software may be freely redistributed under the terms of the GNU
+general public license.
+
+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., 675 Mass Ave, Cambridge, MA 02139, USA.
+"""
+
+import os
+import string
+import sys
+import traceback
+
+# this is kind of handy, so keep it around for now
+# but we really need to fix out server side logging and error
+# reporting so we don't need it
+def trace_me():
+   x = traceback.extract_stack()
+   bar = string.join(traceback.format_list(x))
+   return bar
+
+
+def daemonize(pidfile=None):
+    """
+    Daemonize this process with the UNIX double-fork trick.
+    Writes the new PID to the provided file name if not None.
+    """
+
+    print pidfile
+    pid = os.fork()
+    if pid > 0:
+       sys.exit(0)
+    os.setsid()
+    os.umask(0)
+    pid = os.fork()
+
+
+    if pid > 0:
+       if pidfile is not None:
+          open(pidfile, "w").write(str(pid))
+       sys.exit(0)