Python ctypes 模块，wstring_at() 实例源码

def _decode_surrogatepass(data, codec):
    """Like data.decode(codec, 'surrogatepass') but makes utf-16-le/be work
    on Python < 3.4 + Windows

    https://bugs.python.org/issue27971

    Raises UnicodeDecodeError, LookupError
    """

    try:
        return data.decode(codec, _surrogatepass)
    except UnicodeDecodeError:
        if not _codec_can_decode_with_surrogatepass(codec):
            if _normalize_codec(codec) == "utf-16-be":
                data = _swap_bytes(data)
                codec = "utf-16-le"
            if _normalize_codec(codec) == "utf-16-le":
                buffer_ = ctypes.create_string_buffer(data + b"\x00\x00")
                value = ctypes.wstring_at(buffer_, len(data) // 2)
                if value.encode("utf-16-le", _surrogatepass) != data:
                    raise
                return value
            else:
                raise
        else:
            raise

def get_env(shell=None, for_subprocess=False):
    """
    Return environment variables for the current user

    :param shell:
        The shell to get the env from - unused on Windows

    :param for_subprocess:
        If True, and the code is being run in Sublime Text 2, the result will
        be byte strings instead of unicode strings

    :return:
        A 2-element tuple:

         - [0] unicode string shell path
         - [1] env dict with keys and values as unicode strings
    """

    shell = os.environ['ComSpec']
    if not isinstance(shell, str_cls) and for_subprocess is False:
        shell = shell.decode(_sys_encoding)

    if sys.version_info < (3,) and for_subprocess is False:
        str_pointer = kernel32.GetEnvironmentStringsW()
        string = ctypes.wstring_at(str_pointer)

        values = {}
        while string != '':
            if string[0].isalpha():
                name, value = string.split(u'=', 1)
                values[name.upper()] = value
            # Include the trailing null byte, and measure each
            # char as 2 bytes since Windows uses UTF-16 for
            # wide chars
            str_pointer += (len(string) + 1) * 2
            string = ctypes.wstring_at(str_pointer)
    else:
        values = dict(os.environ)

    return (shell, values)

def FillDeviceAttributes(device, descriptor):
  """Fill out the attributes of the device.

  Fills the devices HidAttributes and product string
  into the descriptor.

  Args:
    device: A handle to the open device
    descriptor: The DeviceDescriptor to populate with the
      attributes.

  Returns:
    None

  Raises:
    WindowsError when unable to obtain attributes or product
      string.
  """
  attributes = HidAttributes()
  result = hid.HidD_GetAttributes(device, ctypes.byref(attributes))
  if not result:
    raise ctypes.WinError()

  buf = ctypes.create_string_buffer(1024)
  result = hid.HidD_GetProductString(device, buf, 1024)

  if not result:
    raise ctypes.WinError()

  descriptor.vendor_id = attributes.VendorID
  descriptor.product_id = attributes.ProductID
  descriptor.product_string = ctypes.wstring_at(buf)

def EnumKey(key, index):
    """This calls the Windows RegEnumKeyEx function in a Unicode safe way."""
    buf = ctypes.create_unicode_buffer(257)
    length = ctypes.wintypes.DWORD(257)
    rc = RegEnumKeyEx(key.handle, index, ctypes.cast(buf, ctypes.c_wchar_p),
                      ctypes.byref(length), LPDWORD(), ctypes.c_wchar_p(),
                      LPDWORD(), ctypes.POINTER(FileTime)())
    if rc != 0:
        raise ctypes.WinError(2)

    return ctypes.wstring_at(buf, length.value).rstrip(u"\x00")

def Reg2Py(data, size, data_type):
    if data_type == _winreg.REG_DWORD:
        if size == 0:
            return 0
        return ctypes.cast(data, ctypes.POINTER(ctypes.c_int)).contents.value
    elif data_type == _winreg.REG_SZ or data_type == _winreg.REG_EXPAND_SZ:
        return ctypes.wstring_at(data, size // 2).rstrip(u"\x00")
    elif data_type == _winreg.REG_MULTI_SZ:
        return ctypes.wstring_at(data, size // 2).rstrip(u"\x00").split(u"\x00")
    else:
        if size == 0:
            return None
        return ctypes.string_at(data, size)

def _safe_wstring_at(self, buff, offset):
        idx = 0
        length = 0
        while offset + idx + 1 < len(buff):
            if buff[offset+idx] == b'\x00' and buff[offset+idx+1] == b'\x00':
                return ct.wstring_at(ct.addressof(buff) + offset, length)
            idx += 2
            length += 1
        return None # terminating null char not found