Python ctypes:访问冲突 [英] Python ctypes: Access violation

问题描述

我正在尝试为第三方C DLL编写Python包装器.

I am trying to write a Python wrapper for a 3rd-party C DLL.

函数 WolaInit 初始化库并返回一个句柄，以用于后续函数调用.

The function WolaInit initializes the library and returns a handle to be used for subsequent function calls.

import ctypes

# Load WOLA DLL into memory.
wolaDLL = ctypes.WinDLL("wola.dll")

# Function prototypes
WolaInit = wolaDLL.WolaInit
WolaInit.restype = ctypes.c_ulong
WolaInit.argtypes = [
        ctypes.c_int,              # La
        ctypes.c_int,              # Ls
        ctypes.c_int,              # R
        ctypes.c_int,              # N
        ctypes.c_int]              # stacking

WolaGetStacking = wolaDLL.WolaGetStacking
WolaGetStacking.restype = ctypes.c_int
WolaGetStacking.argtypes = [ctypes.c_ulong]

# Parameters
La = 128
Ls = 64
R = 32
N = 8
stacking = 0

# Initialize
wolaHandle = WolaInit(La, Ls, R, N, stacking)
print('Handle: ' + hex(wolaHandle))

# Test if library was initialized
stackingVal = WolaGetStacking(wolaHandle)

但是，当使用返回的句柄时，会发生访问冲突(访问冲突的地址对应于句柄值加上一个额外的偏移量).

However when using the returned handle, an access violation occurs (the address of the access violation corresponds to the handle value plus an additional offset).

Handle: 0x3fe22310

Traceback (most recent call last):

  File "<ipython-input-47-5ba1f23d5c33>", line 1, in <module>
    runfile('D:/Projects/Desyncra_611110600/Simulations/WOLA/wola.py', wdir='D:/Projects/Desyncra_611110600/Simulations/WOLA')

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 710, in runfile
    execfile(filename, namespace)

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 101, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "D:/Projects/Desyncra_611110600/Simulations/WOLA/wola.py", line 69, in <module>
    stackingVal = WolaGetStacking(wolaHandle)

OSError: exception: access violation reading 0x000000003FE22328

这种访问冲突的原因可能是什么?如何解决?

What could be the reason for this access violation and how to resolve it?

推荐答案

句柄通常实现为指针.在64位系统上，指针是64位的.在Windows上， c_ulong 是32位.我认为您正在截断句柄，但是没有看到函数原型，这只是一个理论. c_void_p 可能是更适合该句柄的类型.

Handles are typically implemented as pointers. On 64-bit systems, pointers are 64-bit. On Windows, c_ulong is 32-bits. I think you are truncating the handle, but without seeing the function prototypes it is only a theory. c_void_p may be a more appropriate type for the handle.

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