Thanks. I will try to fix the problem this evening. On Sat, Dec 26, 2009 at 12:43 AM, Nikolaus Rath <Nikolaus@rath.org> wrote:

Hello,

Py++ translates the struct

typedef int cb_fun_t(char *); struct info {   cb_fun_t* cb_fun;   int flag; };

into the Python Structure

class info(ctypes.Structure):    """class info""" info._fields_ = [ #class info    ("cb_fun", ctypes.POINTER( ctypes.CFUNCTYPE( ctypes.c_int, ctypes.c_char_p ) )),    ("flag", ctypes.c_int), ]

This is wrong and produces segfaults. The correct version is

class info(ctypes.Structure):    """class info""" info._fields_ = [ #class info    ("cb_fun", ctypes.CFUNCTYPE( ctypes.c_int, ctypes.c_char_p ) ),    ("flag", ctypes.c_int), ]

I have attached a small example that demonstrates the problem. lib.c is a small C library, build_api.py creates the broken api.py with Py++. api_correct.py is the manually corrected API with the correct structure. call.py demonstrates that the first API segfaults and the second API works:

$ python call.py Calling do_callback with flag=7 do_callback called with flag=7 cb_fun received 'Hello World' cb_fun returns 42 cb_fun returned 42 do_callback returned 42 Calling do_callback with flag=7 do_callback called with flag=7 Segmentation fault

Please let me know if you can reproduce the problem. It took me quite some time to figure this out.

Best,

  -Nikolaus

--  »Time flies like an arrow, fruit flies like a Banana.«

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