avoid unicode paths because of ctypes

#http://msdn.microsoft.com/en-us/library/windows/desktop/dd374130
#http://code.google.com/p/pywinauto/source/browse/pywinauto/win32defines.py?r=ab2f9eb3fc0cfb5d2faaa4326ca7d598474a39ca
from ctypes import *
from ctypes.wintypes import *
import sys

def wide2multibyte(fn):
    """Map a UTF-16 (wide character) string to a new character string. The new
    character string is not necessarily from a multibyte character set.
    Objective: take a unicode string and convert it to a multibyte string that
    Windows can use to represent file names in e.g. Chinese (mbcs will only work
    if the host system 'happens to be' in the right geographical location)."""
    if not sys.platform.startswith("win"):
        return fn

    # constants, taken from pywinauto package
    CP_UTF8 = 65001 # Variable c_int
    CP_ACP = 0      # Variable c_int
    NULL = 0        # Variable c_int
    LPBOOL = POINTER(c_long)

    fnEnc = fn.encode("utf-16-le")
    codePage = CP_UTF8 # --> Ergo: lpDefaultChar, lpUsedDefaultChar must be NULL
    codePage = CP_ACP
    dwFlags = 0
    lpWideCharStr = fnEnc
    cchWideChar = len(fn)   # counts the number of chars, not bytes
    lpMultiByteStr = create_string_buffer(len(fnEnc))
    cbMultiByte = 0
    lpDefaultChar = c_char_p(NULL)  # ???
    lpUsedDefaultChar = c_int(NULL)

    #Returns the number of bytes written to the buffer pointed to by lpMultiByteStr if successful.
    wideCharToMultiByte = windll.kernel32.WideCharToMultiByte
    wideCharToMultiByte.restype = c_int
    wideCharToMultiByte.argtypes = [UINT, DWORD, LPCWSTR,
                                    c_int, LPSTR, c_int,
                                    LPCSTR, LPBOOL]
    # why don't ArgumentErrors have a zero-based origin?
    # E.g. 'ArgumentError: argument 1:...' means 'wrong type for codePage parameter'!

    # determine size
    mbcssize = wideCharToMultiByte(codePage, dwFlags, lpWideCharStr,
                                   cchWideChar, lpMultiByteStr, cbMultiByte,
                                   lpDefaultChar, lpUsedDefaultChar)
    # do conversion
    retcode = wideCharToMultiByte(codePage, dwFlags, lpWideCharStr,
                                  cchWideChar, lpMultiByteStr, mbcssize,
                                  lpDefaultChar, lpUsedDefaultChar)
    print retcode
    print mbcssize
    print repr(lpMultiByteStr.value), lpMultiByteStr.value

    if mbcssize <= 0:
        getLastError = windll.kernel32.GetLastError
        getLastError.restype = DWORD
        retcodes = {122: "ERROR_INSUFFICIENT_BUFFER",
                    1004: "ERROR_INVALID_FLAGS",
                    87: "ERROR_INVALID_PARAMETER",
                    1113: "ERROR_NO_UNICODE_TRANSLATION"}
        retcode = getLastError()
        print "Error:", retcodes.get(retcode, retcode) # error code: 0
    return lpMultiByteStr.value

fn = u'\u0c0f\u0c2e\u0c02\u0c21\u0c40' + '.txt'
wide2multibyte(fn)