在Python中使用ctypes使用C ++代码

Question

I have the following C++ and both functions return int 0 which indicate a success.

#include "stdafx.h"
#include <iostream>
#include "scapi.h"


int main() {

    int ret;

    ret = sc_LoginByLogon(L"hostname.domain.ltd", L"admin", L"pass");
    std::cout << "LoginByLogon: " << ret << std::endl;

    void* out_p;

    ret = sc_GetUserInfoByUserLogon(L"username", &out_p);
    std::cout << "GetUserInfoByUserLogon: " << ret << std::endl;
}

I'm now trying to create a wrapper in Python for these two functions and have come up with the following code:

import sys
import ctypes
from ctypes import *

# Load DLL into memory.
class SUserInfoApiV4(Structure):
    INTRFDEF_SIZE_RESERVED = 32
    _fields_ = [
                 ('m_nStructLength', c_int),
                 ('m_nVersion', c_short),
                 ('m_nSubVersion', c_short),
                 ('m_achReserved', c_char * (INTRFDEF_SIZE_RESERVED - sizeof(c_long))),
                 ('m_nAccessRights', c_long),
                 ('m_nUserType', c_short),
                 ('m_nUserId', c_int),
                 ('m_nSubRights', c_long),
                 ('m_nNotUsed1', c_int),
                 ('m_wzFullName', c_wchar * 101),
                 ('m_wzDescription', c_wchar * 101),
                 ('m_wzEMail', c_wchar * 101),
                 ('m_wzUserLogon', c_wchar * 21),
                 ('m_wzPassword', c_wchar * 17),
                 ('m_szCardNo', c_char * 40),
                 ('m_szPINCode', c_char * 5),
                 ('m_szPUKCode', c_char * 9),
                 ('m_nLogonFails', c_short),
                 ('m_bUserLocked', c_short),
                 ('m_bUserDisabled', c_short),
                 ('m_bAvoidPin', c_short),
                 ('m_bPrintAll', c_short),
                 ('m_bCardOpen', c_short),
                 ('m_nBillingModel', c_short),
                 ('m_nAccountingModel', c_short),
                 ('m_nUserRights', c_int),
                 ('m_bAllowEncryption', c_short),
                 ('m_bAllowCheckPrinting', c_char),
                 ('m_bAllowPmail', c_char),
                 ('m_bDenyRetain', c_char),
                 ('m_lCreationDate', c_long),
                 ('m_lLastLogin', c_long),
                 ('m_nServerId', c_int),
                 ('m_nDomainId', c_int),
                 ('m_nTreeNodeId', c_int),
                 ('m_nNid', c_int),
                 ('m_wzCostCode', c_wchar * 51)
    ]

def main(argv):
    # import library
    lib = ctypes.cdll.LoadLibrary('scAPI.dll')

    # login
    login = lib.sc_LoginByLogon('hostname.domain.ltd', 'admin', 'pass')

    # sc_GetUserInfoByUserLogon
    SUserInfoApiV4p = POINTER(SUserInfoApiV4)
    sc_GetUserInfoByUserLogon = lib.sc_GetUserInfoByUserLogon
    sc_GetUserInfoByUserLogon.argtypes = [c_wchar_p, POINTER(SUserInfoApiV4p)]
    sc_GetUserInfoByUserLogon.restype = c_int

    # get user object
    out_p = SUserInfoApiV4p()
    user = sc_GetUserInfoByUserLogon('username', byref(out_p))

    # debug
    print 'LoginByLogon: ' + str(login)
    print 'GetUserInfoByUserLogon: ' + str(user)
    #print 'Full name:', out_p.contents.m_wzFullName

if __name__ == '__main__':
    main(sys.argv)

The code should have worked, but in Python only sc_LoginByLogon returns 0 while sc_GetUserInfoByUserLogon fails (1). The documentation only states that "1 = General failure", so I'm stuck.

Any obvious ideas would be highly appreciated.

Answer 1

Thanks to Mark Tolonen it now works after explicitly defining the login function before calling. Didn't think I have to since it already returned int 0 which indicates a success.

The only problem is that all properties such as "m_wzFullName" skip the first character for some reason.

Edit: I solved the last bug thanks to this thread: python ctypes pragma pack for byte aligned read

# sc_LoginByLogon
sc_LoginByLogon = lib.sc_LoginByLogon
sc_LoginByLogon.argtypes = [c_wchar_p, c_wchar_p, c_wchar_p]
sc_LoginByLogon.restype = c_int