(1) initial work on a command to import build trees into cobbler in

a really fast, automated way
(2) bundling 2.4's subprocess as sub_process (it's supposed to work) since subprocess isn't available on 2.3 and we want to support lots of 2.3 machines

9 files changed, 1241 insertions, 44 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 34c45a5..a736df2 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -4,6 +4,8 @@ Cobbler CHANGELOG
 * Mon Oct 9 2006 - 0.2.3-1
 - Cobbler now creates a profile and system listing (YAML) in /var needed
   by the next version of koan (which will be 0.2.1)
+- bugfix: enchant should reboot the target box
+- bugfix: enchant should fail if path to koan isn't configured
 
 * Fri Oct 6 2006 - 0.2.2-1
 - bugfix: "--pxe-hostname" made available in CLI and renamed as "--pxe-address"
diff --git a/TODO b/TODO
index d6c5868..f7d2066 100644
--- a/TODO
+++ b/TODO
@@ -6,3 +6,7 @@ cobbler TODO list
   -  Locking
   -  For "enchant", try to verify that syslinux and mkinitrd are installed on the remote.    
   -  "make test" shouldn't overwrite files in /var/lib/cobbler/ 
+
+Non functional:
+  -  an argument parsing overhaul is probably due
+  -  remove the cobbler_msg logic since i18n isn't likely
diff --git a/cobbler.pod b/cobbler.pod
index ec96f29..5627277 100644
--- a/cobbler.pod
+++ b/cobbler.pod
@@ -136,16 +136,13 @@ Example: --pxe-arch=ia64
 Advanced feature.
 
 If cobbler is configured to generate the dhcpd.conf file, use this
-setting to pin a certain MAC address to a specific dhcp hostname.  This corresponds to the "fixed-address" field in dhcpd.conf.
+setting to pin a certain hostname or IP to a given MAC address.  This corresponds to the "fixed-address" field in dhcpd.conf.
 
-When using this setting, be sure that the "--name" given to the "system add" command is a MAC address or no per-system record in dhcpd.conf can be generated.
+When using this setting for IA64 machines, be sure that the "--name" given to the "system add" command is a MAC address or no per-system record in dhcpd.conf can be generated. 
 
-Example: ---pxe-address="foo.example.com"
-
-The pxe-address value should be an IP address in dotted decimal notation.
-
-NOTE: Due to a limitation in elilo (IA64 bootloader), this parameter must ALSO be used even if dhcpd.conf files are not being managed by cobbler AND you want to PXE provision IA64 systems.  
+Example: ---pxe-address=192.168.1.50
 
+NOTE: Due to a limitation in elilo (IA64 bootloader), this parameter must ALSO be used even if dhcpd.conf files are not being managed by cobbler AND you want to PXE provision IA64 systems using a handwritten dhcpd.conf.  Also, for IA64, the value of pxe-address must be an IP, and not a hostname, even though hostnames work for X86.  Thankfully, if you don't have IA64 systems, there are a lot less rules.
 
 =back
 
@@ -251,6 +248,30 @@ Running "enchant" will replace the operating system of the target machine, so us
 
 Usage:  B<cobbler enchant --name=<ip|hostname> --profile=<string> --password=<string>>
 
+=head2 IMPORTING TREES
+
+It is sometimes useful to import an existing directory tree containing a large amount of kernel and initrd images and make "cobbler distro add" calls for each of them.   The "cobbler import" command automates this, and initially names the distros based on the paths they were found in.
+
+For this to work, there can only be one kernel and initrd in each directory, anywhere down in the tree.  
+
+Only images found in directories leaf nodes named "pxe", "pxeboot", or "xen" will be added.  Somewhere higher up in the directory tree, there needs to be a path containing something like "i386" or "x86_64" indicating the architecture.  This is because the import command tries to be smart enough to not import architectures it can't support.
+
+The import command will find new distributions and automatically add them if no existing cobbler distribution references the same files.  Existing cobbler distributions, even ones that no longer point to valid locations, will not be deleted, though warnings will be generated about orphaned distributions.
+
+Import can be run repeatedly with no adverse affect to existing configurations.
+
+Directory tree example (importing /mnt/foo)
+
+/mnt/foo/nightly/rawhide-200610111/tree-ppc <-------------- NOT imported
+/mnt/foo/nightly/rawhide-200610111/tree-i386/images/pxe <-- gets imported
+/mnt/foo/nightly/rawhide-200610111/tree-i386/images/xen <-- gets imported
+/mnt/foo/nightly/rawhide-200610111/tree-ia64/...        <-- gets imported
+/mnt/foo/nightly/rawhide-200610111/tree-x86_64/...      <-- gets imported
+
+Distributions are named after fragments of the path name seperated with underscores instead of slashes.  These names are obviously ugly so you may want to rename them after the fact.
+
+Usage: B<cobbler import --path=<path>>
+
 =head2 TWEAKING
 
 Enterprising users can edit the files in /var/lib/cobbler directly versus using the command line.  The repair
diff --git a/cobbler/action_enchant.py b/cobbler/action_enchant.py
index b956db7..0cd72d7 100644
--- a/cobbler/action_enchant.py
+++ b/cobbler/action_enchant.py
@@ -16,7 +16,6 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 import cexceptions
 import os
 import os.path
-import subprocess
 import pexpect
 import pxssh
 import traceback
diff --git a/cobbler/action_sync.py b/cobbler/action_sync.py
index 9d0725d..11d60d8 100644
--- a/cobbler/action_sync.py
+++ b/cobbler/action_sync.py
@@ -18,7 +18,7 @@ import os.path
 import shutil
 import time
 import yaml # Howell-Clark version
-import subprocess
+import sub_process
 import sys
 from Cheetah.Template import Template
 
@@ -68,7 +68,7 @@ class BootSync:
         if self.settings.manage_dhcp:
             self.write_dhcp_file()
             try:
-               retcode = subprocess.call("/sbin/service dhcpd restart", shell=True)
+               retcode = sub_process.call("/sbin/service dhcpd restart", shell=True)
                if retcode != 0:
                    print >>sys.stderr, "Warning: dhcpd restart failed"
             except OSError, e:
@@ -393,8 +393,10 @@ class BootSync:
                 f2 = os.path.join(self.settings.tftpboot, "pxelinux.cfg", f1)
             if system.pxe_arch == "ia64":
                 # elilo expects files to be named "$name.conf" in the root
-                if system.pxe_address == "" or system.pxe_address is None:
-                   raise cexceptions.CobblerException("exc_ia64_noip",system.name)
+                # and can not do files based on the MAC address
+                if system.pxe_address == "" or system.pxe_address is None or not utils.is_ip(system.pxe_address):
+                    raise cexceptions.CobblerException("exc_ia64_noip",system.name)
+
                 
                 filename = "%s.conf" % self.get_pxe_filename(system.pxe_address) 
                 f2 = os.path.join(self.settings.tftpboot, filename)
diff --git a/cobbler/cobbler.py b/cobbler/cobbler.py
index 8a57a62..886a24b 100755
--- a/cobbler/cobbler.py
+++ b/cobbler/cobbler.py
@@ -136,37 +136,51 @@ class BootCLI:
         on_ok = lambda: self.api.systems().add(sys)
         return self.apply_args(args,commands,on_ok)
 
+    def apply_cmd_args(self,args,accepted,required,err_msg):
+        """
+        This is a variation of the command parsing done in apply_args but
+        is not centric to things in the object graph.  
+        """
+        for arg in args:
+             try:
+                 (first, last) = (None, None)
+                 (first, last) = arg.split("=")
+             except:
+                 if first is None: 
+                     continue
+                 raise cexceptions.CobblerException(err_msg)
+             if first in accepted.keys():
+                 accepted[first] = last
+             else:
+                 raise cexceptions.CobblerException("weird_arg",first)
+        for arg in required:
+            if accepted[arg] is None:
+                raise cexceptions.CobblerException(err_msg)
+        return accepted
+
+    def import_distros(self,args):
+        stored = {
+            "--path" : None
+        }
+        required = [ "--path" ]
+        results = self.apply_cmd_args(args,stored,required,"import_args")
+        return self.api.import_distros(stored["--path"])
+
     def enchant_system(self,args):
         """
         Replace an existing running password.
         """
-        sysname = None
-        profile = None
-        password = None
-        first = None
-        last = None
-        for args in self.args:
-            try:
-                (first, last) = (None, None)
-                (first, last) = args.split("=")
-            except:
-                if first == None:
-                   continue
-                raise cexceptions.CobblerException("enchant_args")
-            if first == "--name":
-                sysname = last
-                continue
-            if first == "--profile":
-                profile = last
-                continue
-            if first == "--password":
-                password = last
-                continue
-            else:
-                raise cexceptions.CobblerException("weird_arg",args)
-        if sysname is None or profile is None or password is None:
-            raise cexceptions.CobblerException("enchant_args")
-        return self.api.enchant(sysname,profile,password)
+        stored = {
+           "--name" : None,
+           "--profile" : None,
+           "--password" : None
+        }
+        required = [ "--name", "--profile", "--password" ]
+        results = self.apply_cmd_args(args,stored,required,"enchant_args")
+        return self.api.enchant(stored["--name"], 
+            stored["--profile"],
+            stored["--password"]
+        )
 
     def profile_edit(self,args):
         """
diff --git a/cobbler/cobbler_msg.py b/cobbler/cobbler_msg.py
index 684dc89..ccb8f98 100644
--- a/cobbler/cobbler_msg.py
+++ b/cobbler/cobbler_msg.py
@@ -27,8 +27,10 @@ _msg_table = {
   "no_delete"       : "cobbler could not delete: %s",
   "no_args"         : "this command requires arguments.",
   "missing_options" : "cannot perform this action, more arguments are required",
-  "enchant_args"    : "usage: cobbler enchant --name=<string> --profile=<string> --password=<string>\n",
+  "enchant_args"    : "usage: cobbler enchant --name=<string> --profile=<string> --password=<string>",
   "enchant_failed"  : "enchant failed (%s)",
+  "import_args"     : "usage: cobbler import --path=<path>", 
+  "import_failed"   : "import failed (%s)",
   "unknown_cmd"     : "cobbler doesn't understand '%s'",
   "bad_arg"         : "cobbler was expecting an equal sign in argument '%s'",
   "reject_arg"      : "the value of parameter '%s' isn't valid",
diff --git a/cobbler/item_system.py b/cobbler/item_system.py
index 315ab3a..217e511 100644
--- a/cobbler/item_system.py
+++ b/cobbler/item_system.py
@@ -54,11 +54,15 @@ class System(item.Item):
         self.name = name  # we check it add time, but store the original value.
         return True
 
-    def set_pxe_address(self,hostname):
-        # we allow this to be set to anything and should restrict it
-        if not utils.is_ip(hostname):
+    def set_pxe_address(self,address):
+        # restricting to address as IP only in dhcpd.conf is probably
+        # incorrect ... some people may want to pin the hostname instead.
+        # doing so, however, doesn't allow dhcpd.conf to be managed
+        # by cobbler (since elilo can't do MAC addresses) -- this is 
+        # covered in the man page.
+        if not utils.is_ip(address) and not utils.is_mac(address):
             raise cexceptions.CobblerException("bad_ip")    
-        self.pxe_address = hostname
+        self.pxe_address = address
         return True
 
     def set_profile(self,profile_name):
diff --git a/cobbler/sub_process.py b/cobbler/sub_process.py
new file mode 100644
index 0000000..bbd26c7
--- /dev/null
+++ b/cobbler/sub_process.py
@@ -0,0 +1,1149 @@
+# 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(*args, **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"])
+
+
+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.
+
+
+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)
+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
+
+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
+        class pywintypes:
+            error = IOError
+else:
+    import select
+    import errno
+    import fcntl
+    import pickle
+
+__all__ = ["Popen", "PIPE", "STDOUT", "call"]
+
+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[:]:
+        inst.poll()
+
+PIPE = -1
+STDOUT = -2
+
+
+def call(*args, **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(*args, **kwargs).wait()
+
+
+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()
+
+        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)
+
+        _active.append(self)
+
+
+    def _translate_newlines(self, data):
+        data = data.replace("\r\n", "\n")
+        data = data.replace("\r", "\n")
+        return data
+
+
+    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 == None and stdout == None and stderr == None:
+                return (None, None, None, None, None, None)
+
+            p2cread, p2cwrite = None, None
+            c2pread, c2pwrite = None, None
+            errread, errwrite = None, None
+
+            if stdin == 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 type(stdin) == types.IntType:
+                p2cread = msvcrt.get_osfhandle(stdin)
+            else:
+                # Assuming file-like object
+                p2cread = msvcrt.get_osfhandle(stdin.fileno())
+            p2cread = self._make_inheritable(p2cread)
+
+            if stdout == 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 type(stdout) == types.IntType:
+                c2pwrite = msvcrt.get_osfhandle(stdout)
+            else:
+                # Assuming file-like object
+                c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
+            c2pwrite = self._make_inheritable(c2pwrite)
+
+            if stderr == 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 type(stderr) == types.IntType:
+                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
+            default_startupinfo = STARTUPINFO()
+            if startupinfo == None:
+                startupinfo = default_startupinfo
+            if not None in (p2cread, c2pwrite, errwrite):
+                startupinfo.dwFlags |= STARTF_USESTDHANDLES
+                startupinfo.hStdInput = p2cread
+                startupinfo.hStdOutput = c2pwrite
+                startupinfo.hStdError = errwrite
+
+            if shell:
+                default_startupinfo.dwFlags |= STARTF_USESHOWWINDOW
+                default_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._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 != None:
+                p2cread.Close()
+            if c2pwrite != None:
+                c2pwrite.Close()
+            if errwrite != None:
+                errwrite.Close()
+
+
+        def poll(self):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode == None:
+                if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0:
+                    self.returncode = GetExitCodeProcess(self._handle)
+                    _active.remove(self)
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode == None:
+                obj = WaitForSingleObject(self._handle, INFINITE)
+                self.returncode = GetExitCodeProcess(self._handle)
+                _active.remove(self)
+            return self.returncode
+
+
+        def _readerthread(self, fh, buffer):
+            buffer.append(fh.read())
+
+
+        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)."""
+            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 != 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 != None:
+                stdout = stdout[0]
+            if stderr != 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(open, '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 == None:
+                pass
+            elif stdin == PIPE:
+                p2cread, p2cwrite = os.pipe()
+            elif type(stdin) == types.IntType:
+                p2cread = stdin
+            else:
+                # Assuming file-like object
+                p2cread = stdin.fileno()
+
+            if stdout == None:
+                pass
+            elif stdout == PIPE:
+                c2pread, c2pwrite = os.pipe()
+            elif type(stdout) == types.IntType:
+                c2pwrite = stdout
+            else:
+                # Assuming file-like object
+                c2pwrite = stdout.fileno()
+
+            if stderr == None:
+                pass
+            elif stderr == PIPE:
+                errread, errwrite = os.pipe()
+            elif stderr == STDOUT:
+                errwrite = c2pwrite
+            elif type(stderr) == types.IntType:
+                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 range(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 == 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()
+            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 doesn't close the same
+                    # fd more than once.
+                    if p2cread:
+                        os.close(p2cread)
+                    if c2pwrite and c2pwrite not in (p2cread,):
+                        os.close(c2pwrite)
+                    if errwrite and errwrite not in (p2cread, c2pwrite):
+                        os.close(errwrite)
+
+                    # Close all other fds, if asked for
+                    if close_fds:
+                        self._close_fds(but=errpipe_write)
+
+                    if cwd != None:
+                        os.chdir(cwd)
+
+                    if preexec_fn:
+                        apply(preexec_fn)
+
+                    if env == 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!")
+
+            _active.remove(self)
+
+
+        def poll(self):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode == None:
+                try:
+                    pid, sts = os.waitpid(self.pid, os.WNOHANG)
+                    if pid == self.pid:
+                        self._handle_exitstatus(sts)
+                except os.error:
+                    pass
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode == None:
+                pid, sts = os.waitpid(self.pid, 0)
+                self._handle_exitstatus(sts)
+            return self.returncode
+
+
+        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)."""
+            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 != None:
+                stdout = ''.join(stdout)
+            if stderr != 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(open, '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()