Mini Shell

# flake8: noqa
# fmt: off
## issue: https://bugs.python.org/issue19264

import ctypes
import os
import platform
import subprocess
from ctypes import Structure, WinError, byref, c_char_p, c_void_p, c_wchar, c_wchar_p, sizeof, windll
from ctypes.wintypes import BOOL, BYTE, DWORD, HANDLE, LPCWSTR, LPVOID, LPWSTR, WORD

import _subprocess

##
## Types
##

CREATE_UNICODE_ENVIRONMENT = 0x00000400
LPCTSTR = c_char_p
LPTSTR = c_wchar_p
LPSECURITY_ATTRIBUTES = c_void_p
LPBYTE  = ctypes.POINTER(BYTE)

class STARTUPINFOW(Structure):
    _fields_ = [
        ("cb",              DWORD),  ("lpReserved",    LPWSTR),
        ("lpDesktop",       LPWSTR), ("lpTitle",       LPWSTR),
        ("dwX",             DWORD),  ("dwY",           DWORD),
        ("dwXSize",         DWORD),  ("dwYSize",       DWORD),
        ("dwXCountChars",   DWORD),  ("dwYCountChars", DWORD),
        ("dwFillAtrribute", DWORD),  ("dwFlags",       DWORD),
        ("wShowWindow",     WORD),   ("cbReserved2",   WORD),
        ("lpReserved2",     LPBYTE), ("hStdInput",     HANDLE),
        ("hStdOutput",      HANDLE), ("hStdError",     HANDLE),
    ]

LPSTARTUPINFOW = ctypes.POINTER(STARTUPINFOW)


class PROCESS_INFORMATION(Structure):
    _fields_ = [
        ("hProcess",         HANDLE), ("hThread",          HANDLE),
        ("dwProcessId",      DWORD),  ("dwThreadId",       DWORD),
    ]

LPPROCESS_INFORMATION = ctypes.POINTER(PROCESS_INFORMATION)


class DUMMY_HANDLE(ctypes.c_void_p):

    def __init__(self, *a, **kw):
        super(DUMMY_HANDLE, self).__init__(*a, **kw)
        self.closed = False

    def Close(self):
        if not self.closed:
            windll.kernel32.CloseHandle(self)
            self.closed = True

    def __int__(self):
        return self.value


CreateProcessW = windll.kernel32.CreateProcessW
CreateProcessW.argtypes = [
    LPCWSTR, LPWSTR, LPSECURITY_ATTRIBUTES,
    LPSECURITY_ATTRIBUTES, BOOL, DWORD, LPVOID, LPCWSTR,
    LPSTARTUPINFOW, LPPROCESS_INFORMATION,
]
CreateProcessW.restype = BOOL


##
## Patched functions/classes
##

def CreateProcess(
    executable, args, _p_attr, _t_attr,
    inherit_handles, creation_flags, env, cwd,
    startup_info,
):
    """Create a process supporting unicode executable and args for win32

    Python implementation of CreateProcess using CreateProcessW for Win32

    """

    si = STARTUPINFOW(
        dwFlags=startup_info.dwFlags,
        wShowWindow=startup_info.wShowWindow,
        cb=sizeof(STARTUPINFOW),
        ## XXXvlab: not sure of the casting here to ints.
        hStdInput=startup_info.hStdInput if startup_info.hStdInput is None else int(startup_info.hStdInput),
        hStdOutput=startup_info.hStdOutput if startup_info.hStdOutput is None else int(startup_info.hStdOutput),
        hStdError=startup_info.hStdError if startup_info.hStdError is None else int(startup_info.hStdError),
    )

    wenv = None
    if env is not None:
        ## LPCWSTR seems to be c_wchar_p, so let's say CWSTR is c_wchar
        env = (
            unicode("").join([
            unicode("%s=%s\0") % (k, v)
            for k, v in env.items()
            ])
        ) + unicode("\0")
        wenv = (c_wchar * len(env))()
        wenv.value = env

    wcwd = None
    if cwd is not None:
        wcwd = unicode(cwd)

    pi = PROCESS_INFORMATION()
    creation_flags |= CREATE_UNICODE_ENVIRONMENT

    if CreateProcessW(
        executable, args, None, None,
        inherit_handles, creation_flags,
        wenv, wcwd, byref(si), byref(pi),
    ):
        return (
            DUMMY_HANDLE(pi.hProcess), DUMMY_HANDLE(pi.hThread),
            pi.dwProcessId, pi.dwThreadId,
        )
    raise WinError()


class Popen(subprocess.Popen):
    """This superseeds Popen and corrects a bug in cPython 2.7 implem"""

    def _execute_child(
        self, args, executable, preexec_fn, close_fds,
        cwd, env, universal_newlines,
        startupinfo, creationflags, shell, to_close,
        p2cread, p2cwrite,
        c2pread, c2pwrite,
        errread, errwrite,
    ):
        """Code from part of _execute_child from Python 2.7 (9fbb65e)

        There are only 2 little changes concerning the construction of
        the the final string in shell mode: we preempt the creation of
        the command string when shell is True, because original function
        will try to encode unicode args which we want to avoid to be able to
        sending it as-is to ``CreateProcess``.

        """
        if startupinfo is None:
            startupinfo = subprocess.STARTUPINFO()
        if not isinstance(args, subprocess.types.StringTypes):
            args = [i if isinstance(i, bytes) else i.encode('utf-8') for i in args]
            args = subprocess.list2cmdline(args)
            if platform.python_implementation() == "CPython":
                args = args.decode('utf-8')
        startupinfo.dwFlags |= _subprocess.STARTF_USESHOWWINDOW
        startupinfo.wShowWindow = _subprocess.SW_HIDE
        env = os.environ if env is None else env
        comspec = env.get("COMSPEC", unicode("cmd.exe"))
        if (
            _subprocess.GetVersion() >= 0x80000000 or
            os.path.basename(comspec).lower() == "command.com"
        ):
            w9xpopen = self._find_w9xpopen()
            args = unicode('"%s" %s') % (w9xpopen, args)
            creationflags |= _subprocess.CREATE_NEW_CONSOLE

        super(Popen, self)._execute_child(
            args, executable,
            preexec_fn, close_fds, cwd, env, universal_newlines,
            startupinfo, creationflags, False, to_close, p2cread,
            p2cwrite, c2pread, c2pwrite, errread, errwrite,
        )

_subprocess.CreateProcess = CreateProcess
# fmt: on