Menu
For low-level purposes, I need to construct a ctypes pointer from an arbitrary address, given as an integer. For instance:
INTP = ctypes.POINTER(ctypes.c_int) p = INTP(0x12345678) # i *know* this is the address But all such attempts result in
TypeError: expected c_long instead of int Is there anything I can do to overcome this? In case someone wonders why I need this, it's done so as to extract the OVERLAPPED struct from a win32file.PyOVERLAPPED, for integrating ctypes-exposed functions with win32file wrapped APIs.
Thanks,
-Tomer
351
ctypes is a foreign function library for Python. It provides C compatible data types, and allows calling functions in DLLs or shared libraries. It can be used to wrap these libraries in pure Python.
It is a big C++ codebase with a (very) thin python wrapper which uses CDLL to load the C++ and call some C functions that are available to allow primitive python scripting of the code.
c_char_p is a subclass of _SimpleCData , with _type_ == 'z' . The __init__ method calls the type's setfunc , which for simple type 'z' is z_set . In Python 2, the z_set function (2.7.
You can use ctypes.cast(addr, type). I'll extend your example to acquire an address via a known object, to demonstrate:
INTP = ctypes.POINTER(ctypes.c_int) num = ctypes.c_int(42) addr = ctypes.addressof(num) print 'address:', addr, type(addr) ptr = ctypes.cast(addr, INTP) print 'pointer:', ptr print 'value:', ptr[0] Output:
address: 4301122528 <type 'int'> pointer: <__main__.LP_c_int object at 0x1005decb0> value: 42 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
