我使用
Python 3.6.0和ctypes来访问从.dll导出的函数.我想通过使用paramflags参数实例化函数原型来访问函数. .dll中的一个函数是静态定义的,因此不会导出.但是.dll还包含一个指向该函数并导出的函数指针.
这是.dll的简化版本
typedef void ( *function ) ( int *output, int input );
__declspec( dllexport ) void two( int *output, int input );
__declspec( dllexport ) extern const function four;
void two( int *output, int input ) {
*output = 2 * input;
}
static void three( int *output, int input ) {
*output = 3 * input;
}
const function four = three;
这是我的Python代码
import ctypes
dll = ctypes.cdll.test
# calling two( ) as an attribute of dll
two = dll.two
two.argtypes = [ ctypes.POINTER( ctypes.c_int ), ctypes.c_int ]
two.restype = None
output = ctypes.c_int( )
# output = c_long(2)
two( ctypes.byref( output ), 1 )
print( ‘output =’, output )
# calling two( ) by instantiating a function prototype with paramflags
function = ctypes.CFUNCTYPE( None, ctypes.POINTER( ctypes.c_int ), ctypes.c_int )
paramflags = ( ( 2, ‘output’ ), ( 1, ‘input’ ) )
two = function( ( ‘two’, dll ), paramflags )
# output = 2
output = two( 1 )
print( ‘output =’, output )
# I can call four( ) using in_dll( )
four = function.in_dll( dll, ‘four’ )
output = ctypes.c_int( )
# output = c_long(3)
four( ctypes.byref( output ), 1 )
print( ‘output =’, output )
# but not as an attribute of dll
four = dll.four
four.argtypes = [ ctypes.POINTER( ctypes.c_int ), ctypes.c_int ]
four.restype = None
output = ctypes.c_int( )
# this results in a “OSError: exception: access violation writing 0x6C0C3064”
four( ctypes.byref( output ), 1 )
print( ‘output =’, output )
# nor by instantiating a function prototype
paramflags = ( ( 2, ‘output’ ), ( 1, ‘input’ ) )
four = function( ( ‘four’, dll ), paramflags )
# this results in a “OSError: exception: access violation writing 0x6C0C3064”
output = four( 1 )
print( ‘output =’, output )
我可以访问两个()作为dll的属性,并通过实例化一个函数原型.但是,当我尝试使用four()时,我得到“OSError：exception：access violation writing 0x6C0C3064”.经过大量的实验,我发现我可以使用in_dll()访问four(),但后来我无法应用paramflags功能.
有没有办法访问four()并使用paramflags？
注意：我不想更改dll(它不是我的项目的一部分),我试图在Python端解决它.