Help: 64bit python call c and got OSError: exception: access violation writing 0xFFFFFFFF99222A60

[Jason Qian]

Again, thanks for the help. Everything is working fine after the changes.

Here is one more new issue needs some help.

On c side,

   The createService function can pass a  callback handler as second
parameter.
   Without callback handler, it works fine. But if we add the callback
handler,  the application will give a exception due to the pointer of
callback handler = NULL;

   Not sure, why the callback handler missed up, when the app calling from
python.

Thanks

-- python

lib.createService.argtypes=[ctypes.c_void_p,ctypes.c_char_p]
lib.createService.restype=ctypes.c_int

def create_services(self,servicename):
        result=lib.createService(self.obj,servicename)
        return result

--c --

__declspec(dllexport) int createService(void* obj, const char* serviceName)
{
     return ((myPythonAPI*)obj)->createService(serviceName);
}

int myPythonAPI::createService(const char* serviceName)
{
     //case 1 :
     //This works fine
     createService(methodname);

    //case 2
    //This will not working,
     InvocationCallback serviceCallback;
    createService(methodname, &serviceCallback);
}











On Mon, Jan 22, 2018 at 5:58 PM, Jason Qian <jqian at tibco.com> wrote:

> Thanks you very much, fixed the problem :)
>
> On Mon, Jan 22, 2018 at 4:28 PM, Random832 <random832 at fastmail.com> wrote:
>
>> On Mon, Jan 22, 2018, at 16:00, Jason Qian via Python-list wrote:
>> > Hello!
>> >
>> >   I am using ctypes on Windows to interface with a dll  and it works
>> fine
>> > on Linux and windows 32-bit python.  But, when using 64-bit python, we
>> got
>> > error "exception: access violation writing 0xFFFFFFFF99222A60".
>>
>> You are treating the obj type (myPythonAPI *) as c_int, which is only 32
>> bits. You should be using a pointer type instead (ideally you should be
>> using void * and c_void_p, so Python doesn't need the class definition.)
>> Don't forget to set lib.loadInstance.restype as well.
>>
>> > __declspec(dllexport) myPythonAPI* loadInstance(){ return new
>> > myPythonAPI(); }
>> > __declspec(dllexport) int createService(myPythonAPI* obj, const char*
>> > serviceName) { eturn obj->createService(serviceName);
>>
>> > lib = cdll.LoadLibrary('xxxxxxx.dll')
>> >
>> > lib.createService.argtypes=[c_int,ctypes.c_char_p]
>> > lib.createService.restype=ctypes.c_int
>> >
>> > class myDriver(object):
>> > def init(self):
>> > self.obj = lib.loadInstance()
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
>
>