Question

在我的cpp文件中

extern "C" {
    Password obj;
    _declspec(dllexport) BOOL decrypt(const char *encryptedPassword, char *password, size_t *sizeOfThePasswordPtr)
    {
        return obj.decrypt(encryptedPassword, password, sizeOfThePasswordPtr);
    }
}

在我的python文件中：

    lib = ctypes.WinDLL(os.path.join(baseDir, "basicLib.dll"))
    encryptedValue = ctypes.c_char_p('absfdxfd')
    decryptedValue = ctypes.c_char_p()
    size = ctypes.c_size_t(1024)
    lib.decrypt.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_size_t]
    lib.decrypt(encryptedValue, decryptedValue, size)

调用函数时出现此错误WindowsError: exception: access violation reading 0x0000000000000400。问题是因为encryptedValue参数。

只有在设置encryptedValue = ctypes.c_char_p()时它才有效，但如果我传入一些值，我会得到异常。请告诉我原因。

Answer 1

# WinDLL is for __stdcall functions.  Use CDLL.
# This is most likely the cause of your exception because the parameters
# are marshalled on the stack incorrectly.
lib = ctypes.CDLL(os.path.join(baseDir, "basicLib.dll"))

# No need to explicitly create c_char_p objects if you declare argtypes,
# but make sure it is a byte string if using Python 3
encryptedValue = b'absfdxfd'

# Create a writable buffer for the output.
decryptedValue = ctypes.create_string_buffer(1024)

# Good
lib.decrypt.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_size_t]

# No need to declare explicit c_size_t() object either.
lib.decrypt(encryptedValue, decryptedValue, len(decryptedValue))

Ctypes：WindowsError：exception：调用C ++函数时访问冲突读取0x0000000000000400

1 个答案: