[Telemetry] Add timeout to telemetry run_tests

tools/telemetry/third_party/subprocess32/subprocess32.py

+# subprocess - Subprocesses with accessible I/O streams
+#
+# For more information about this module, see PEP 324.
+#
+# Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se>
+#
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/3.3/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=True, shell=False,
+            cwd=None, env=None, universal_newlines=False,
+            startupinfo=None, creationflags=0,
+            restore_signals=True, start_new_session=False, pass_fds=()):
+
+
+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 POSIX, 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 POSIX, 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.
+
+On POSIX, if preexec_fn is set to a callable object, this object will be
+called in the child process just before the child is executed.  The use
+of preexec_fn is not thread safe, using it in the presence of threads
+could lead to a deadlock in the child process before the new executable
+is executed.
+
+If close_fds is true, all file descriptors except 0, 1 and 2 will be
+closed before the child process is executed.  The default for close_fds
+varies by platform:  Always true on POSIX.  True when stdin/stdout/stderr
+are None on Windows, false otherwise.
+
+pass_fds is an optional sequence of file descriptors to keep open between the
+parent and child.  Providing any pass_fds implicitly sets close_fds to true.
+
+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.
+
+On POSIX, if restore_signals is True all signals that Python sets to
+SIG_IGN are restored to SIG_DFL in the child process before the exec.
+Currently this includes the SIGPIPE, SIGXFZ and SIGXFSZ signals.  This
+parameter does nothing on Windows.
+
+On POSIX, if start_new_session is True, the setsid() system call will be made
+in the child process prior to executing the command.
+
+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 old 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 some 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"])
+
+check_output(*popenargs, **kwargs):
+    Run command with arguments and return its output as a byte string.
+
+    If the exit code was non-zero it raises a CalledProcessError.  The
+    CalledProcessError object will have the return code in the returncode
+    attribute and output in the output attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    output = check_output(["ls", "-l", "/dev/null"])
+
+
+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() and check_output() 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 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).
+
+    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 (POSIX 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)
+
+On Unix, os.popen2, os.popen3 and os.popen4 also accept a sequence as
+the command to execute, in which case arguments will be passed
+directly to the program without shell intervention.  This usage can be
+replaced as follows:
+
+(child_stdin, child_stdout) = os.popen2(["/bin/ls", "-l"], mode,
+                                        bufsize)
+==>
+p = Popen(["/bin/ls", "-l"], bufsize=bufsize, stdin=PIPE, stdout=PIPE)
+(child_stdin, child_stdout) = (p.stdin, p.stdout)
+
+Return code handling translates as follows:
+
+pipe = os.popen("cmd", 'w')
+...
+rc = pipe.close()
+if rc is not None and rc % 256:
+    print "There were some errors"
+==>
+process = Popen("cmd", 'w', shell=True, stdin=PIPE)
+...
+process.stdin.close()
+if process.wait() != 0:
+    print "There were some errors"
+
+
+Replacing popen2.*
+------------------
+(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)
+
+On Unix, popen2 also accepts a sequence as the command to execute, in
+which case arguments will be passed directly to the program without
+shell intervention.  This usage can be replaced as follows:
+
+(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 popen2.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 exceptions
+import types
+import time
+import traceback
+import gc
+import signal
+
+# Exception classes used by this module.
+class CalledProcessError(Exception):
+    """This exception is raised when a process run by check_call() or
+    check_output() returns a non-zero exit status.
+    The exit status will be stored in the returncode attribute;
+    check_output() will also store the output in the output attribute.
+    """
+    def __init__(self, returncode, cmd, output=None):
+        self.returncode = returncode
+        self.cmd = cmd
+        self.output = output
+    def __str__(self):
+        return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+
+
+class TimeoutExpired(Exception):
+    """This exception is raised when the timeout expires while waiting for a
+    child process.
+    """
+    def __init__(self, cmd, timeout, output=None):
+        self.cmd = cmd
+        self.timeout = timeout
+        self.output = output
+
+    def __str__(self):
+        return ("Command '%s' timed out after %s seconds" %
+                (self.cmd, self.timeout))
+
+
+if mswindows:
+    import threading
+    import msvcrt
+    import _subprocess
+    class STARTUPINFO:
+        dwFlags = 0
+        hStdInput = None
+        hStdOutput = None
+        hStdError = None
+        wShowWindow = 0
+    class pywintypes:
+        error = IOError
+else:
+    import select
+    _has_poll = hasattr(select, 'poll')
+    import errno
+    import fcntl
+    import pickle
+
+    try:
+        import _posixsubprocess
+    except ImportError:
+        _posixsubprocess = None
+        import warnings
+        warnings.warn("The _posixsubprocess module is not being used. "
+                      "Child process reliability may suffer if your "
+                      "program uses threads.", RuntimeWarning)
+    try:
+        import threading
+    except ImportError:
+        import dummy_threading as threading
+
+    # When select or poll has indicated that the file is writable,
+    # we can write up to _PIPE_BUF bytes without risk of blocking.
+    # POSIX defines PIPE_BUF as >= 512.
+    _PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+
+    _FD_CLOEXEC = getattr(fcntl, 'FD_CLOEXEC', 1)
+
+    def _set_cloexec(fd, cloexec):
+        old = fcntl.fcntl(fd, fcntl.F_GETFD)
+        if cloexec:
+            fcntl.fcntl(fd, fcntl.F_SETFD, old | _FD_CLOEXEC)
+        else:
+            fcntl.fcntl(fd, fcntl.F_SETFD, old & ~_FD_CLOEXEC)
+
+    if _posixsubprocess:
+        _create_pipe = _posixsubprocess.cloexec_pipe
+    else:
+        def _create_pipe():
+            fds = os.pipe()
+            _set_cloexec(fds[0], True)
+            _set_cloexec(fds[1], True)
+            return fds
+
+__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call",
+           "check_output", "CalledProcessError"]
+
+if mswindows:
+    from _subprocess import (CREATE_NEW_CONSOLE, CREATE_NEW_PROCESS_GROUP,
+                             STD_INPUT_HANDLE, STD_OUTPUT_HANDLE,
+                             STD_ERROR_HANDLE, SW_HIDE,
+                             STARTF_USESTDHANDLES, STARTF_USESHOWWINDOW)
+
+    __all__.extend(["CREATE_NEW_CONSOLE", "CREATE_NEW_PROCESS_GROUP",
+                    "STD_INPUT_HANDLE", "STD_OUTPUT_HANDLE",
+                    "STD_ERROR_HANDLE", "SW_HIDE",
+                    "STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW"])
+try:
+    MAXFD = os.sysconf("SC_OPEN_MAX")
+except:
+    MAXFD = 256
+
+# This lists holds Popen instances for which the underlying process had not
+# exited at the time its __del__ method got called: those processes are wait()ed
+# for synchronously from _cleanup() when a new Popen object is created, to avoid
+# zombie processes.
+_active = []
+
+def _cleanup():
+    for inst in _active[:]:
+        res = inst._internal_poll(_deadstate=sys.maxint)
+        if res is not None:
+            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 _eintr_retry_call(func, *args):
+    while True:
+        try:
+            return func(*args)
+        except (OSError, IOError), e:
+            if e.errno == errno.EINTR:
+                continue
+            raise
+
+
+def _get_exec_path(env=None):
+    """Returns the sequence of directories that will be searched for the
+    named executable (similar to a shell) when launching a process.
+
+    *env* must be an environment variable dict or None.  If *env* is None,
+    os.environ will be used.
+    """
+    if env is None:
+        env = os.environ
+    return env.get('PATH', os.defpath).split(os.pathsep)
+
+
+if hasattr(os, 'get_exec_path'):
+    _get_exec_path = os.get_exec_path
+
+
+def call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete or
+    timeout, then return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+    """
+    timeout = kwargs.pop('timeout', None)
+    p = Popen(*popenargs, **kwargs)
+    try:
+        return p.wait(timeout=timeout)
+    except TimeoutExpired:
+        p.kill()
+        p.wait()
+        raise
+
+
+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 call function.  Example:
+
+    check_call(["ls", "-l"])
+    """
+    retcode = call(*popenargs, **kwargs)
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise CalledProcessError(retcode, cmd)
+    return 0
+
+
+def check_output(*popenargs, **kwargs):
+    r"""Run command with arguments and return its output as a byte string.
+
+    If the exit code was non-zero it raises a CalledProcessError.  The
+    CalledProcessError object will have the return code in the returncode
+    attribute and output in the output attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    >>> check_output(["ls", "-l", "/dev/null"])
+    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
+
+    The stdout argument is not allowed as it is used internally.
+    To capture standard error in the result, use stderr=STDOUT.
+
+    >>> check_output(["/bin/sh", "-c",
+    ...               "ls -l non_existent_file ; exit 0"],
+    ...              stderr=STDOUT)
+    'ls: non_existent_file: No such file or directory\n'
+    """
+    timeout = kwargs.pop('timeout', None)
+    if 'stdout' in kwargs:
+        raise ValueError('stdout argument not allowed, it will be overridden.')
+    process = Popen(stdout=PIPE, *popenargs, **kwargs)
+    try:
+        output, unused_err = process.communicate(timeout=timeout)
+    except TimeoutExpired:
+        process.kill()
+        output, unused_err = process.communicate()
+        raise TimeoutExpired(process.args, timeout, output=output)
+    retcode = process.poll()
+    if retcode:
+        raise CalledProcessError(retcode, process.args, output=output)
+    return output
+
+
+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/en-us/library/17w5ykft.aspx
+    # or search http://msdn.microsoft.com for
+    # "Parsing C++ Command-Line Arguments"
+    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) or not 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 backslashes.
+                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 backslashes, if any.
+        if bs_buf:
+            result.extend(bs_buf)
+
+        if needquote:
+            result.extend(bs_buf)
+            result.append('"')
+
+    return ''.join(result)
+
+
+_PLATFORM_DEFAULT_CLOSE_FDS = object()
+
+
+class Popen(object):
+    def __init__(self, args, bufsize=0, executable=None,
+                 stdin=None, stdout=None, stderr=None,
+                 preexec_fn=None, close_fds=_PLATFORM_DEFAULT_CLOSE_FDS,
+                 shell=False, cwd=None, env=None, universal_newlines=False,
+                 startupinfo=None, creationflags=0,
+                 restore_signals=True, start_new_session=False,
+                 pass_fds=()):
+        """Create new Popen instance."""
+        _cleanup()
+        # Held while anything is calling waitpid before returncode has been
+        # updated to prevent clobbering returncode if wait() or poll() are
+        # called from multiple threads at once.  After acquiring the lock,
+        # code must re-check self.returncode to see if another thread just
+        # finished a waitpid() call.
+        self._waitpid_lock = threading.Lock()
+
+        self._child_created = False
+        self._input = None
+        self._communication_started = 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")
+            any_stdio_set = (stdin is not None or stdout is not None or
+                             stderr is not None)
+            if close_fds is _PLATFORM_DEFAULT_CLOSE_FDS:
+                if any_stdio_set:
+                    close_fds = False
+                else:
+                    close_fds = True
+            elif close_fds and any_stdio_set:
+                raise ValueError(
+                        "close_fds is not supported on Windows platforms"
+                        " if you redirect stdin/stdout/stderr")
+        else:
+            # POSIX
+            if close_fds is _PLATFORM_DEFAULT_CLOSE_FDS:
+                close_fds = True
+            if pass_fds and not close_fds:
+                warnings.warn("pass_fds overriding close_fds.", RuntimeWarning)
+                close_fds = True
+            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.args = args
+        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 -1 when not using PIPEs. The child objects are -1
+        # when not redirecting.
+
+        (p2cread, p2cwrite,
+         c2pread, c2pwrite,
+         errread, errwrite) = self._get_handles(stdin, stdout, stderr)
+
+        if mswindows:
+            if p2cwrite != -1:
+                p2cwrite = msvcrt.open_osfhandle(p2cwrite.Detach(), 0)
+            if c2pread != -1:
+                c2pread = msvcrt.open_osfhandle(c2pread.Detach(), 0)
+            if errread != -1:
+                errread = msvcrt.open_osfhandle(errread.Detach(), 0)
+
+        if p2cwrite != -1:
+            self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
+        if c2pread != -1:
+            if universal_newlines:
+                self.stdout = os.fdopen(c2pread, 'rU', bufsize)
+            else:
+                self.stdout = os.fdopen(c2pread, 'rb', bufsize)
+        if errread != -1:
+            if universal_newlines:
+                self.stderr = os.fdopen(errread, 'rU', bufsize)
+            else:
+                self.stderr = os.fdopen(errread, 'rb', bufsize)
+
+        self._closed_child_pipe_fds = False
+        exception_cleanup_needed = False
+        try:
+            try:
+                self._execute_child(args, executable, preexec_fn, close_fds,
+                                    pass_fds, cwd, env, universal_newlines,
+                                    startupinfo, creationflags, shell,
+                                    p2cread, p2cwrite,
+                                    c2pread, c2pwrite,
+                                    errread, errwrite,
+                                    restore_signals, start_new_session)
+            except:
+                # The cleanup is performed within the finally block rather
+                # than simply within this except block before the raise so
+                # that any exceptions raised and handled within it do not
+                # clobber the exception context we want to propagate upwards.
+                # This is only necessary in Python 2.
+                exception_cleanup_needed = True
+                raise
+        finally:
+            if exception_cleanup_needed:
+                for f in filter(None, (self.stdin, self.stdout, self.stderr)):
+                    try:
+                        f.close()
+                    except EnvironmentError:
+                        pass  # Ignore EBADF or other errors
+
+                if not self._closed_child_pipe_fds:
+                    to_close = []
+                    if stdin == PIPE:
+                        to_close.append(p2cread)
+                    if stdout == PIPE:
+                        to_close.append(c2pwrite)
+                    if stderr == PIPE:
+                        to_close.append(errwrite)
+                    for fd in to_close:
+                        try:
+                            os.close(fd)
+                        except EnvironmentError:
+                            pass
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        if self.stdout:
+            self.stdout.close()
+        if self.stderr:
+            self.stderr.close()
+        if self.stdin:
+            self.stdin.close()
+        # Wait for the process to terminate, to avoid zombies.
+        self.wait()
+
+    def _translate_newlines(self, data):
+        data = data.replace("\r\n", "\n")
+        data = data.replace("\r", "\n")
+        return data
+
+
+    def __del__(self, _maxint=sys.maxint, _active=_active):
+        # If __init__ hasn't had a chance to execute (e.g. if it
+        # was passed an undeclared keyword argument), we don't
+        # have a _child_created attribute at all.
+        if not getattr(self, '_child_created', False):
+            # 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._internal_poll(_deadstate=_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, timeout=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)."""
+
+        if self._communication_started and input:
+            raise ValueError("Cannot send input after starting communication")
+
+        if timeout is not None:
+            endtime = time.time() + timeout
+        else:
+            endtime = None
+
+        # Optimization: If we are not worried about timeouts, we haven't
+        # started communicating, and we have one or zero pipes, using select()
+        # or threads is unnecessary.
+        if (endtime is None and not self._communication_started and
+            [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 = _eintr_retry_call(self.stdout.read)
+                self.stdout.close()
+            elif self.stderr:
+                stderr = _eintr_retry_call(self.stderr.read)
+                self.stderr.close()
+            self.wait()
+            return (stdout, stderr)
+
+        try:
+            stdout, stderr = self._communicate(input, endtime, timeout)
+        finally:
+            self._communication_started = True
+
+        sts = self.wait(timeout=self._remaining_time(endtime))
+
+        return (stdout, stderr)
+
+
+    def poll(self):
+        return self._internal_poll()
+
+
+    def _remaining_time(self, endtime):
+        """Convenience for _communicate when computing timeouts."""
+        if endtime is None:
+            return None
+        else:
+            return endtime - time.time()
+
+
+    def _check_timeout(self, endtime, orig_timeout):
+        """Convenience for checking if a timeout has expired."""
+        if endtime is None:
+            return
+        if time.time() > endtime:
+            raise TimeoutExpired(self.args, orig_timeout)
+
+
+    if mswindows:
+        #
+        # Windows methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tuple with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            if stdin is None and stdout is None and stderr is None:
+                return (-1, -1, -1, -1, -1, -1)
+
+            p2cread, p2cwrite = -1, -1
+            c2pread, c2pwrite = -1, -1
+            errread, errwrite = -1, -1
+
+            if stdin is None:
+                p2cread = _subprocess.GetStdHandle(_subprocess.STD_INPUT_HANDLE)
+                if p2cread is None:
+                    p2cread, _ = _subprocess.CreatePipe(None, 0)
+            elif stdin == PIPE:
+                p2cread, p2cwrite = _subprocess.CreatePipe(None, 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 = _subprocess.GetStdHandle(_subprocess.STD_OUTPUT_HANDLE)
+                if c2pwrite is None:
+                    _, c2pwrite = _subprocess.CreatePipe(None, 0)
+            elif stdout == PIPE:
+                c2pread, c2pwrite = _subprocess.CreatePipe(None, 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 = _subprocess.GetStdHandle(_subprocess.STD_ERROR_HANDLE)
+                if errwrite is None:
+                    _, errwrite = _subprocess.CreatePipe(None, 0)
+            elif stderr == PIPE:
+                errread, errwrite = _subprocess.CreatePipe(None, 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 _subprocess.DuplicateHandle(_subprocess.GetCurrentProcess(),
+                                handle, _subprocess.GetCurrentProcess(), 0, 1,
+                                _subprocess.DUPLICATE_SAME_ACCESS)
+
+
+        def _find_w9xpopen(self):
+            """Find and return absolut path to w9xpopen.exe"""
+            w9xpopen = os.path.join(
+                            os.path.dirname(_subprocess.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,
+                           pass_fds, cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite,
+                           unused_restore_signals, unused_start_new_session):
+            """Execute program (MS Windows version)"""
+
+            assert not pass_fds, "pass_fds not supported on Windows."
+
+            if not isinstance(args, types.StringTypes):
+                args = list2cmdline(args)
+
+            # Process startup details
+            if startupinfo is None:
+                startupinfo = STARTUPINFO()
+            if -1 not in (p2cread, c2pwrite, errwrite):
+                startupinfo.dwFlags |= _subprocess.STARTF_USESTDHANDLES
+                startupinfo.hStdInput = p2cread
+                startupinfo.hStdOutput = c2pwrite
+                startupinfo.hStdError = errwrite
+
+            if shell:
+                startupinfo.dwFlags |= _subprocess.STARTF_USESHOWWINDOW
+                startupinfo.wShowWindow = _subprocess.SW_HIDE
+                comspec = os.environ.get("COMSPEC", "cmd.exe")
+                args = comspec + " /c " + '"%s"' % args
+                if (_subprocess.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 |= _subprocess.CREATE_NEW_CONSOLE
+
+            # Start the process
+            try:
+                try:
+                    hp, ht, pid, tid = _subprocess.CreateProcess(executable, args,
+                                             # no special security
+                                             None, None,
+                                             int(not close_fds),
+                                             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 similar), but
+                    # how can this be done from Python?
+                    raise WindowsError(*e.args)
+            finally:
+                # 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 != -1:
+                    p2cread.Close()
+                if c2pwrite != -1:
+                    c2pwrite.Close()
+                if errwrite != -1:
+                    errwrite.Close()
+
+            # Retain the process handle, but close the thread handle
+            self._child_created = True
+            self._handle = hp
+            self.pid = pid
+            ht.Close()
+
+        def _internal_poll(self, _deadstate=None,
+                _WaitForSingleObject=_subprocess.WaitForSingleObject,
+                _WAIT_OBJECT_0=_subprocess.WAIT_OBJECT_0,
+                _GetExitCodeProcess=_subprocess.GetExitCodeProcess):
+            """Check if child process has terminated.  Returns returncode
+            attribute.
+
+            This method is called by __del__, so it can only refer to objects
+            in its local scope.
+
+            """
+            if self.returncode is None:
+                if _WaitForSingleObject(self._handle, 0) == _WAIT_OBJECT_0:
+                    self.returncode = _GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def wait(self, timeout=None, endtime=None):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if endtime is not None:
+                timeout = self._remaining_time(endtime)
+            if timeout is None:
+                timeout = _subprocess.INFINITE
+            else:
+                timeout = int(timeout * 1000)
+            if self.returncode is None:
+                result = _subprocess.WaitForSingleObject(self._handle, timeout)
+                if result == _subprocess.WAIT_TIMEOUT:
+                    raise TimeoutExpired(self.args, timeout)
+                self.returncode = _subprocess.GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def _readerthread(self, fh, buffer):
+            buffer.append(fh.read())
+            fh.close()
+
+
+        def _communicate(self, input, endtime, orig_timeout):
+            # Start reader threads feeding into a list hanging off of this
+            # object, unless they've already been started.
+            if self.stdout and not hasattr(self, "_stdout_buff"):
+                self._stdout_buff = []
+                self.stdout_thread = \
+                        threading.Thread(target=self._readerthread,
+                                         args=(self.stdout, self._stdout_buff))
+                self.stdout_thread.daemon = True
+                self.stdout_thread.start()
+            if self.stderr and not hasattr(self, "_stderr_buff"):
+                self._stderr_buff = []
+                self.stderr_thread = \
+                        threading.Thread(target=self._readerthread,
+                                         args=(self.stderr, self._stderr_buff))
+                self.stderr_thread.daemon = True
+                self.stderr_thread.start()
+
+            if self.stdin:
+                if input is not None:
+                    self.stdin.write(input)
+                self.stdin.close()
+
+            # Wait for the reader threads, or time out.  If we time out, the
+            # threads remain reading and the fds left open in case the user
+            # calls communicate again.
+            if self.stdout is not None:
+                self.stdout_thread.join(self._remaining_time(endtime))
+                if self.stdout_thread.isAlive():
+                    raise TimeoutExpired(self.args)
+            if self.stderr is not None:
+                self.stderr_thread.join(self._remaining_time(endtime))
+                if self.stderr_thread.isAlive():
+                    raise TimeoutExpired(self.args)
+
+            # Collect the output from and close both pipes, now that we know
+            # both have been read successfully.
+            stdout = None
+            stderr = None
+            if self.stdout:
+                stdout = self._stdout_buff
+                self.stdout.close()
+            if self.stderr:
+                stderr = self._stderr_buff
+                self.stderr.close()
+
+            # 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)
+
+            return (stdout, stderr)
+
+        def send_signal(self, sig):
+            """Send a signal to the process
+            """
+            if sig == signal.SIGTERM:
+                self.terminate()
+            elif sig == signal.CTRL_C_EVENT:
+                os.kill(self.pid, signal.CTRL_C_EVENT)
+            elif sig == signal.CTRL_BREAK_EVENT:
+                os.kill(self.pid, signal.CTRL_BREAK_EVENT)
+            else:
+                raise ValueError("Unsupported signal: %s" % sig)
+
+        def terminate(self):
+            """Terminates the process
+            """
+            _subprocess.TerminateProcess(self._handle, 1)
+
+        kill = terminate
+
+    else:
+        #
+        # POSIX methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tuple with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            p2cread, p2cwrite = -1, -1
+            c2pread, c2pwrite = -1, -1
+            errread, errwrite = -1, -1
+
+            if stdin is None:
+                pass
+            elif stdin == PIPE:
+                p2cread, p2cwrite = _create_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 = _create_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 = _create_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)
+
+
+        if hasattr(os, 'closerange'):  # Introduced in 2.6
+            @staticmethod
+            def _closerange(fd_low, fd_high):
+                os.closerange(fd_low, fd_high)
+        else:
+            @staticmethod
+            def _closerange(fd_low, fd_high):
+                for fd in xrange(fd_low, fd_high):
+                    while True:
+                        try:
+                            os.close(fd)
+                        except (OSError, IOError), e:
+                            if e.errno == errno.EINTR:
+                                continue
+                            break
+
+
+        def _close_fds(self, but):
+            self._closerange(3, but)
+            self._closerange(but + 1, MAXFD)
+
+
+        def _close_all_but_a_sorted_few_fds(self, fds_to_keep):
+            # precondition: fds_to_keep must be sorted and unique
+            start_fd = 3
+            for fd in fds_to_keep:
+                if fd >= start_fd:
+                    self._closerange(start_fd, fd)
+                    start_fd = fd + 1
+            if start_fd <= MAXFD:
+                self._closerange(start_fd, MAXFD)
+
+
+        def _execute_child(self, args, executable, preexec_fn, close_fds,
+                           pass_fds, cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite,
+                           restore_signals, start_new_session):
+            """Execute program (POSIX version)"""
+
+            if isinstance(args, types.StringTypes):
+                args = [args]
+            else:
+                args = list(args)
+
+            if shell:
+                args = ["/bin/sh", "-c"] + args
+                if executable:
+                    args[0] = executable
+
+            if executable is None:
+                executable = args[0]
+            orig_executable = executable
+
+            # For transferring possible exec failure from child to parent.
+            # Data format: "exception name:hex errno:description"
+            # Pickle is not used; it is complex and involves memory allocation.
+            errpipe_read, errpipe_write = _create_pipe()
+            try:
+                try:
+
+                    if _posixsubprocess:
+                        fs_encoding = sys.getfilesystemencoding()
+                        def fs_encode(s):
+                            """Encode s for use in the env, fs or cmdline."""
+                            if isinstance(s, str):
+                                return s
+                            else:
+                                return s.encode(fs_encoding, 'strict')
+
+                        # We must avoid complex work that could involve
+                        # malloc or free in the child process to avoid
+                        # potential deadlocks, thus we do all this here.
+                        # and pass it to fork_exec()
+
+                        if env is not None:
+                            env_list = [fs_encode(k) + '=' + fs_encode(v)
+                                        for k, v in env.items()]
+                        else:
+                            env_list = None  # Use execv instead of execve.
+                        if os.path.dirname(executable):
+                            executable_list = (fs_encode(executable),)
+                        else:
+                            # This matches the behavior of os._execvpe().
+                            path_list = _get_exec_path(env)
+                            executable_list = (os.path.join(dir, executable)
+                                               for dir in path_list)
+                            executable_list = tuple(fs_encode(exe)
+                                                    for exe in executable_list)
+                        fds_to_keep = set(pass_fds)
+                        fds_to_keep.add(errpipe_write)
+                        self.pid = _posixsubprocess.fork_exec(
+                                args, executable_list,
+                                close_fds, sorted(fds_to_keep), cwd, env_list,
+                                p2cread, p2cwrite, c2pread, c2pwrite,
+                                errread, errwrite,
+                                errpipe_read, errpipe_write,
+                                restore_signals, start_new_session, preexec_fn)
+                        self._child_created = True
+                    else:
+                        # Pure Python implementation: It is not thread safe.
+                        # This implementation may deadlock in the child if your
+                        # parent process has any other threads running.
+
+                        gc_was_enabled = gc.isenabled()
+                        # Disable gc to avoid bug where gc -> file_dealloc ->
+                        # write to stderr -> hang.  See issue1336
+                        gc.disable()
+                        try:
+                            self.pid = os.fork()
+                        except:
+                            if gc_was_enabled:
+                                gc.enable()
+                            raise
+                        self._child_created = True
+                        if self.pid == 0:
+                            # Child
+                            reached_preexec = False
+                            try:
+                                # Close parent's pipe ends
+                                if p2cwrite != -1:
+                                    os.close(p2cwrite)
+                                if c2pread != -1:
+                                    os.close(c2pread)
+                                if errread != -1:
+                                    os.close(errread)
+                                os.close(errpipe_read)
+
+                                # When duping fds, if there arises a situation
+                                # where one of the fds is either 0, 1 or 2, it
+                                # is possible that it is overwritten (#12607).
+                                if c2pwrite == 0:
+                                    c2pwrite = os.dup(c2pwrite)
+                                if errwrite == 0 or errwrite == 1:
+                                    errwrite = os.dup(errwrite)
+
+                                # Dup fds for child
+                                def _dup2(a, b):
+                                    # dup2() removes the CLOEXEC flag but
+                                    # we must do it ourselves if dup2()
+                                    # would be a no-op (issue #10806).
+                                    if a == b:
+                                        _set_cloexec(a, False)
+                                    elif a != -1:
+                                        os.dup2(a, b)
+                                _dup2(p2cread, 0)
+                                _dup2(c2pwrite, 1)
+                                _dup2(errwrite, 2)
+
+                                # Close pipe fds.  Make sure we don't close the
+                                # same fd more than once, or standard fds.
+                                closed = set()
+                                for fd in [p2cread, c2pwrite, errwrite]:
+                                    if fd > 2 and fd not in closed:
+                                        os.close(fd)
+                                        closed.add(fd)
+
+                                if cwd is not None:
+                                    os.chdir(cwd)
+
+                                # This is a copy of Python/pythonrun.c
+                                # _Py_RestoreSignals().  If that were exposed
+                                # as a sys._py_restoresignals func it would be
+                                # better.. but this pure python implementation
+                                # isn't likely to be used much anymore.
+                                if restore_signals:
+                                    signals = ('SIGPIPE', 'SIGXFZ', 'SIGXFSZ')
+                                    for sig in signals:
+                                        if hasattr(signal, sig):
+                                            signal.signal(getattr(signal, sig),
+                                                          signal.SIG_DFL)
+
+                                if start_new_session and hasattr(os, 'setsid'):
+                                    os.setsid()
+
+                                reached_preexec = True
+                                if preexec_fn:
+                                    preexec_fn()
+
+                                # Close all other fds, if asked for - after
+                                # preexec_fn(), which may open FDs.
+                                if close_fds:
+                                    if pass_fds:
+                                        fds_to_keep = set(pass_fds)
+                                        fds_to_keep.add(errpipe_write)
+                                        self._close_all_but_a_sorted_few_fds(
+                                                sorted(fds_to_keep))
+                                    else:
+                                        self._close_fds(but=errpipe_write)
+
+                                if env is None:
+                                    os.execvp(executable, args)
+                                else:
+                                    os.execvpe(executable, args, env)
+
+                            except:
+                                try:
+                                    exc_type, exc_value = sys.exc_info()[:2]
+                                    if isinstance(exc_value, OSError):
+                                        errno_num = exc_value.errno
+                                    else:
+                                        errno_num = 0
+                                    if not reached_preexec:
+                                        exc_value = "noexec"
+                                    message = '%s:%x:%s' % (exc_type.__name__,
+                                                            errno_num, exc_value)
+                                    os.write(errpipe_write, message)
+                                except Exception:
+                                    # We MUST not allow anything odd happening
+                                    # above to prevent us from exiting below.
+                                    pass
+
+                            # This exitcode won't be reported to applications
+                            # so it really doesn't matter what we return.
+                            os._exit(255)
+
+                        # Parent
+                        if gc_was_enabled:
+                            gc.enable()
+                finally:
+                    # be sure the FD is closed no matter what
+                    os.close(errpipe_write)
+
+                # A pair of non -1s means we created both fds and are
+                # responsible for closing them.
+                if p2cread != -1 and p2cwrite != -1:
+                    os.close(p2cread)
+                if c2pwrite != -1 and c2pread != -1:
+                    os.close(c2pwrite)
+                if errwrite != -1 and errread != -1:
+                    os.close(errwrite)
+                # Prevent a double close of these fds from __init__ on error.
+                self._closed_child_pipe_fds = True
+
+                # Wait for exec to fail or succeed; possibly raising exception
+                # exception (limited in size)
+                errpipe_data = ''
+                while True:
+                    part = _eintr_retry_call(os.read, errpipe_read, 50000)
+                    errpipe_data += part
+                    if not part or len(errpipe_data) > 50000:
+                        break
+            finally:
+                # be sure the FD is closed no matter what
+                os.close(errpipe_read)
+
+            if errpipe_data != "":
+                try:
+                    _eintr_retry_call(os.waitpid, self.pid, 0)
+                except OSError, e:
+                    if e.errno != errno.ECHILD:
+                        raise
+                try:
+                    exception_name, hex_errno, err_msg = (
+                            errpipe_data.split(':', 2))
+                except ValueError:
+                    exception_name = 'RuntimeError'
+                    hex_errno = '0'
+                    err_msg = ('Bad exception data from child: ' +
+                               repr(errpipe_data))
+                child_exception_type = getattr(
+                        exceptions, exception_name, RuntimeError)
+                if issubclass(child_exception_type, OSError) and hex_errno:
+                    errno_num = int(hex_errno, 16)
+                    child_exec_never_called = (err_msg == "noexec")
+                    if child_exec_never_called:
+                        err_msg = ""
+                    if errno_num != 0:
+                        err_msg = os.strerror(errno_num)
+                        if errno_num == errno.ENOENT:
+                            if child_exec_never_called:
+                                # The error must be from chdir(cwd).
+                                err_msg += ': ' + repr(cwd)
+                            else:
+                                err_msg += ': ' + repr(orig_executable)
+                    raise child_exception_type(errno_num, err_msg)
+                try:
+                    exception = child_exception_type(err_msg)
+                except Exception:
+                    exception = RuntimeError(
+                            'Could not re-raise %r exception from the'
+                            ' child with error message %r' %
+                            (child_exception_type, err_msg))
+                raise exception
+
+
+        def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
+                _WTERMSIG=os.WTERMSIG, _WIFEXITED=os.WIFEXITED,
+                _WEXITSTATUS=os.WEXITSTATUS):
+            """All callers to this function MUST hold self._waitpid_lock."""
+            # This method is called (indirectly) by __del__, so it cannot
+            # refer to anything outside of its local scope."""
+            if _WIFSIGNALED(sts):
+                self.returncode = -_WTERMSIG(sts)
+            elif _WIFEXITED(sts):
+                self.returncode = _WEXITSTATUS(sts)
+            else:
+                # Should never happen
+                raise RuntimeError("Unknown child exit status!")
+
+
+        def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid,
+                _WNOHANG=os.WNOHANG, _os_error=os.error, _ECHILD=errno.ECHILD):
+            """Check if child process has terminated.  Returns returncode
+            attribute.
+
+            This method is called by __del__, so it cannot reference anything
+            outside of the local scope (nor can any methods it calls).
+
+            """
+            if self.returncode is None:
+                if not self._waitpid_lock.acquire(False):
+                    # Something else is busy calling waitpid.  Don't allow two
+                    # at once.  We know nothing yet.
+                    return None
+                try:
+                    try:
+                        if self.returncode is not None:
+                            return self.returncode  # Another thread waited.
+                        pid, sts = _waitpid(self.pid, _WNOHANG)
+                        if pid == self.pid:
+                            self._handle_exitstatus(sts)
+                    except _os_error, e:
+                        if _deadstate is not None:
+                            self.returncode = _deadstate
+                        elif e.errno == _ECHILD:
+                            # This happens if SIGCLD is set to be ignored or
+                            # waiting for child processes has otherwise been
+                            # disabled for our process.  This child is dead, we
+                            # can't get the status.
+                            # http://bugs.python.org/issue15756
+                            self.returncode = 0
+                finally:
+                    self._waitpid_lock.release()
+            return self.returncode
+
+
+        def _try_wait(self, wait_flags):
+            """All callers to this function MUST hold self._waitpid_lock."""
+            try:
+                (pid, sts) = _eintr_retry_call(os.waitpid, self.pid, wait_flags)
+            except OSError, e:
+                if e.errno != errno.ECHILD:
+                    raise
+                # This happens if SIGCLD is set to be ignored or waiting
+                # for child processes has otherwise been disabled for our
+                # process.  This child is dead, we can't get the status.
+                pid = self.pid
+                sts = 0
+            return (pid, sts)
+
+
+        def wait(self, timeout=None, endtime=None):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode is not None:
+                return self.returncode
+
+            # endtime is preferred to timeout.  timeout is only used for
+            # printing.
+            if endtime is not None or timeout is not None:
+                if endtime is None:
+                    endtime = time.time() + timeout
+                elif timeout is None:
+                    timeout = self._remaining_time(endtime)
+
+            if endtime is not None:
+                # Enter a busy loop if we have a timeout.  This busy loop was
+                # cribbed from Lib/threading.py in Thread.wait() at r71065.
+                delay = 0.0005 # 500 us -> initial delay of 1 ms
+                while True:
+                    if self._waitpid_lock.acquire(False):
+                        try:
+                            if self.returncode is not None:
+                                break  # Another thread waited.
+                            (pid, sts) = self._try_wait(os.WNOHANG)
+                            assert pid == self.pid or pid == 0
+                            if pid == self.pid:
+                                self._handle_exitstatus(sts)
+                                break
+                        finally:
+                            self._waitpid_lock.release()
+                    remaining = self._remaining_time(endtime)
+                    if remaining <= 0:
+                        raise TimeoutExpired(self.args, timeout)
+                    delay = min(delay * 2, remaining, .05)
+                    time.sleep(delay)
+            else:
+                while self.returncode is None:
+                    self._waitpid_lock.acquire()
+                    try:
+                        if self.returncode is not None:
+                            break  # Another thread waited.
+                        (pid, sts) = self._try_wait(0)
+                        # Check the pid and loop as waitpid has been known to
+                        # return 0 even without WNOHANG in odd situations.
+                        # http://bugs.python.org/issue14396.
+                        if pid == self.pid:
+                            self._handle_exitstatus(sts)
+                    finally:
+                        self._waitpid_lock.release()
+            return self.returncode
+
+
+        def _communicate(self, input, endtime, orig_timeout):
+            if self.stdin and not self._communication_started:
+                # Flush stdio buffer.  This might block, if the user has
+                # been writing to .stdin in an uncontrolled fashion.
+                self.stdin.flush()
+                if not input:
+                    self.stdin.close()
+
+            if _has_poll:
+                stdout, stderr = self._communicate_with_poll(input, endtime,
+                                                             orig_timeout)
+            else:
+                stdout, stderr = self._communicate_with_select(input, endtime,
+                                                               orig_timeout)
+
+            self.wait(timeout=self._remaining_time(endtime))
+
+            # 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)
+
+            return (stdout, stderr)
+
+
+        def _communicate_with_poll(self, input, endtime, orig_timeout):
+            stdout = None # Return
+            stderr = None # Return
+
+            if not self._communication_started:
+                self._fd2file = {}
+
+            poller = select.poll()
+            def register_and_append(file_obj, eventmask):
+                poller.register(file_obj.fileno(), eventmask)
+                self._fd2file[file_obj.fileno()] = file_obj
+
+            def close_unregister_and_remove(fd):
+                poller.unregister(fd)
+                self._fd2file[fd].close()
+                self._fd2file.pop(fd)
+
+            if self.stdin and input:
+                register_and_append(self.stdin, select.POLLOUT)
+
+            # Only create this mapping if we haven't already.
+            if not self._communication_started:
+                self._fd2output = {}
+                if self.stdout:
+                    self._fd2output[self.stdout.fileno()] = []
+                if self.stderr:
+                    self._fd2output[self.stderr.fileno()] = []
+
+            select_POLLIN_POLLPRI = select.POLLIN | select.POLLPRI
+            if self.stdout:
+                register_and_append(self.stdout, select_POLLIN_POLLPRI)
+                stdout = self._fd2output[self.stdout.fileno()]
+            if self.stderr:
+                register_and_append(self.stderr, select_POLLIN_POLLPRI)
+                stderr = self._fd2output[self.stderr.fileno()]
+
+            # Save the input here so that if we time out while communicating,
+            # we can continue sending input if we retry.
+            if self.stdin and self._input is None:
+                self._input_offset = 0
+                self._input = input
+                if self.universal_newlines and isinstance(self._input, unicode):
+                    self._input = self._input.encode(
+                            self.stdin.encoding or sys.getdefaultencoding())
+
+            while self._fd2file:
+                try:
+                    ready = poller.poll(self._remaining_time(endtime))
+                except select.error, e:
+                    if e.args[0] == errno.EINTR:
+                        continue
+                    raise
+                self._check_timeout(endtime, orig_timeout)
+
+                for fd, mode in ready:
+                    if mode & select.POLLOUT:
+                        chunk = self._input[self._input_offset :
+                                            self._input_offset + _PIPE_BUF]
+                        self._input_offset += os.write(fd, chunk)
+                        if self._input_offset >= len(self._input):
+                            close_unregister_and_remove(fd)
+                    elif mode & select_POLLIN_POLLPRI:
+                        data = os.read(fd, 4096)
+                        if not data:
+                            close_unregister_and_remove(fd)
+                        self._fd2output[fd].append(data)
+                    else:
+                        # Ignore hang up or errors.
+                        close_unregister_and_remove(fd)
+
+            return (stdout, stderr)
+
+
+        def _communicate_with_select(self, input, endtime, orig_timeout):
+            if not self._communication_started:
+                self._read_set = []
+                self._write_set = []
+                if self.stdin and input:
+                    self._write_set.append(self.stdin)
+                if self.stdout:
+                    self._read_set.append(self.stdout)
+                if self.stderr:
+                    self._read_set.append(self.stderr)
+
+            if self.stdin and self._input is None:
+                self._input_offset = 0
+                self._input = input
+                if self.universal_newlines and isinstance(self._input, unicode):
+                    self._input = self._input.encode(
+                            self.stdin.encoding or sys.getdefaultencoding())
+
+            stdout = None # Return
+            stderr = None # Return
+
+            if self.stdout:
+                if not self._communication_started:
+                    self._stdout_buff = []
+                stdout = self._stdout_buff
+            if self.stderr:
+                if not self._communication_started:
+                    self._stderr_buff = []
+                stderr = self._stderr_buff
+
+            while self._read_set or self._write_set:
+                try:
+                    (rlist, wlist, xlist) = \
+                        select.select(self._read_set, self._write_set, [],
+                                      self._remaining_time(endtime))
+                except select.error, e:
+                    if e.args[0] == errno.EINTR:
+                        continue
+                    raise
+
+                # According to the docs, returning three empty lists indicates
+                # that the timeout expired.
+                if not (rlist or wlist or xlist):
+                    raise TimeoutExpired(self.args, orig_timeout)
+                # We also check what time it is ourselves for good measure.
+                self._check_timeout(endtime, orig_timeout)
+
+                if self.stdin in wlist:
+                    chunk = self._input[self._input_offset :
+                                        self._input_offset + _PIPE_BUF]
+                    bytes_written = os.write(self.stdin.fileno(), chunk)
+                    self._input_offset += bytes_written
+                    if self._input_offset >= len(self._input):
+                        self.stdin.close()
+                        self._write_set.remove(self.stdin)
+
+                if self.stdout in rlist:
+                    data = os.read(self.stdout.fileno(), 1024)
+                    if data == "":
+                        self.stdout.close()
+                        self._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()
+                        self._read_set.remove(self.stderr)
+                    stderr.append(data)
+
+            return (stdout, stderr)
+
+
+        def send_signal(self, sig):
+            """Send a signal to the process
+            """
+            os.kill(self.pid, sig)
+
+        def terminate(self):
+            """Terminate the process with SIGTERM
+            """
+            self.send_signal(signal.SIGTERM)
+
+        def kill(self):
+            """Kill the process with SIGKILL
+            """
+            self.send_signal(signal.SIGKILL)