__init__.py 文件源码

def ioctl_fn_ptr_r(request, datatype, return_python=None):
    """ Create a helper function for invoking a ioctl() read call.

    This function creates a helper function for creating a ioctl() read function.
    It will call the ioctl() function with a pointer to data, and return the contents
    of the data after the call.

    If the datatype is a integer type (int, long, etc), it will be returned as a python int or long.

    :param request: The ioctl request to call.
    :param datatype: The data type of the data returned by the ioctl() call.
    :param return_python: Whether we should attempt to convert the return data to a Python value. Defaults to True for fundamental ctypes data types.
    :return: A function for invoking the specified ioctl().

    :Example:
      ::

          import ctypes
          import os
          import ioctl
          import ioctl.linux
          RNDGETENTCNT = ioctl.linux.IOR('R', 0x00, ctypes.c_int)
          rndgetentcnt = ioctl.ioctl_fn_ptr_r(RNDGETENTCNT, ctypes.c_int)
          fd = os.open('/dev/random', os.O_RDONLY)
          entropy_avail = rndgetentcnt(fd)
    """

    check_request(request)
    check_ctypes_datatype(datatype)
    if return_python is not None and not isinstance(return_python, bool):
        raise TypeError('return_python must be None or a boolean, but was {}'.format(return_python.__class__.__name__))


    if return_python is None:
        return_python = issubclass(datatype, ctypes._SimpleCData)

    def fn(fd):
        check_fd(fd)
        value = datatype()
        ioctl(fd, request, ctypes.byref(value))
        if return_python:
            return value.value
        else:
            return value
    return fn