通过Ctypes从C到Python-将函数指针的结构包装为静态函数

本文介绍了通过Ctypes从C到Python-将函数指针的结构包装为静态函数的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 我在C库中有这样的结构。 DataFn中的函数指针指向静态函数。I have structs in a C library that are like this.The function pointers in DataFn point to static functions. .h struct Data { int i; int *array;};typedef struct { bool (* const fn1) (struct Data*, const char *source); ....} DataFn;extern DataFn const DATAFUNC使用objdump，该表仅包含DATAFUNC和其他一些东西来自gcc。Using objdump, the table only contains DATAFUNC and a few other things from gcc.这在C语言中很好，在其中调用fn1就像DATAFUNC.fn1（...，...），但是如何将其包装这样就可以在python w / ctypes中调用fn1了吗？This is fine in C where calling fn1 would go like DATAFUNC.fn1(..., ...), but how would something like this be wrapped around so fn1 can be called in python w/ ctypes?示例python libc = ctypes.cdll.LoadLibrary("./data.so")print(libc.DATAFUNC)导致 < _FuncPtr对象位于0x6ffffcd7430> 与此类似，但是没有 推荐答案 [Python 3.Docs]：ctypes-Python的外部函数库包含eve 我相信缺少的主要部分是 ctypes 的 in_dll 方法>类型（访问从dll导出的值部分）。I believe that the main piece missing, was the in_dll method of a ctypes type (Accessing values exported from dll section).除此之外，为了与 C 一起使用数据，您需要让 Python 知道数据格式。这适用于：Other than that, in order to work with C data, you need to let Python know of the data format. That applies to: struct s。通过子类化 ctypes定义 Python 对应对象。结构 函数指针（适用于您的情况）。使用 ctypes定义它们。CFUNCTYPE structs. Define Python counterparts by subclassing ctypes.StructureFunction pointers (applies to your case). Define them using ctypes.CFUNCTYPE我准备了一个简化的示例来说明以上。请注意，为了简化操作，我没有进行任何错误处理（检查 NULL （应该是您应该））。I prepared a simplified example that illustrates the above. Note that I didn't do any error handling (checking for NULLs (which you should)), to keep things simple. ch ：struct Data { int i;};typedef struct { int (* const fn1) (struct Data*, const char*);} DataFn;extern DataFn const DATAFUNC; cc ：#include <stdio.h>#include "c.h"static int func1(struct Data *pData, const char *source) { printf("From C - Data.i: [%d], source: [%s]\n", pData->i, source); return -255;}DataFn const DATAFUNC = {&func1}; code00.py ：#!/usr/bin/env python3import sysfrom ctypes import c_int, c_char_p, Structure, CDLL, CFUNCTYPE, POINTER, byrefclass Data(Structure): _fields_ = [ ("i", c_int), ]fn1_type = CFUNCTYPE(c_int, POINTER(Data), c_char_p)class DataFn(Structure): _fields_ = [ ("fn1", fn1_type), ]def main(): data = Data(127) dll = CDLL("./c.so") data_func = DataFn.in_dll(dll, "DATAFUNC") ret = data_func.fn1(byref(data), "abcd".encode()) print("DATAFUNC.fn1 returned {:d}".format(ret))if __name__ == "__main__": print("Python {:s} on {:s}\n".format(sys.version, sys.platform)) main() 输出： [cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q049962265]> lsc.c c.h code00.py[cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q049962265]> gcc -shared -fPIC -o c.so c.c[cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q049962265]> lsc.c c.h code.py c.so[cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q049962265]> objdump -t c.so | grep DATAFUNC0000000000200e10 g O .data.rel.ro 0000000000000008 DATAFUNC[cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q049962265]> python3 code00.pyPython 3.5.2 (default, Nov 23 2017, 16:37:01)[GCC 5.4.0 20160609] on linuxFrom C - Data.i: [127], source: [abcd]DATAFUNC.fn1 returned -255 这篇关于通过Ctypes从C到Python-将函数指针的结构包装为静态函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！