Access Violation using Python Ctypes

I am trying to import and use a function from a DLL using Pythons ctypes module, but I keep getting this error:

Windows Error: exception: access violation writing 0x0000002C

I've had a look at the other questions on similar topics on here, but none seem to be able to provide an answer that works. My current code is as follows:

from ctypes import *

dll = "./WinlicenseSDK/WinlicenseSDK.dll"

mydll = cdll.LoadLibrary(dll)

name = c_char_p("A.N. Body")
org = c_char_p("ACME")
pcID = c_char_p("APC44567")
zero = c_int(0)
licenseKey = create_string_buffer("")    

mydll.WLGenLicenseFileKey(HASH, name, org, pcID, zero, zero, zero, zero, zero, licenseKey)

Context: I'm investigating licensing techniques for a piece of software. The above function generates a license key from hashing the parameters.

The last parameter for the WLGenLicenseFileKey is a string buffer that the generated key is written to.

I tried setting the argtypes for the function with mydll.WLGenLicenseFileKey.argtypes = ... but this won't work as there is not a string buffer ctypes raw type as there is for strings, ints, floats etc.

Can anybody tell me where I am going wrong?

EDIT:

The C/C++ function definition:

int WLGenLicenseFileKeyW(    
wchar_t* pLicenseHash,     
wchar_t* pUserName,     
wchar_t* pOrganization,    
wchar_t* pCustomData,     
wchar_t* pMachineID,   
int NumDays,    
int NumExec,    
SYSTEMTIME* pExpirationDate,     
int CountryId,     
int Runtime,     
int GlobalTime,    
char* pBufferOut    
);

That is all the information that the documentation gives on the function.

The length of your licenseKey buffer is one byte, and you are not passing Unicode strings. I'm not in front of my PC, but I this should be close assuming your parameters are otherwise correct. Make sure to call the W version of the function. You also don't need to create the exact types as long as they are ints and pointers.

buffer = create_string_buffer(REQUIRED_BUFSIZE)
mydll.WLGenLicenseKeyW(u"A.N. Body", u"ACME", u"APC44567", None, None, 0, 0, None, 0, 0, 0, buffer)

If you do want to use argtypes, then this is what you want:

mydll.WLGenLicenseKeyW.argtypes = [c_wchar_t,c_wchar_t,c_wchar_t,c_wchar_t,c_wchar_t,c_int,c_int,c_void_p,c_int,c_int,c_int,c_char_p]

SYSTEMTIME would also need to be defined if you want to pass something besides NULL.

edit

I found some documentation. The function uses the stdcall calling convention, so use:

mydll = WinDLL(dll)