python通过swig实现的C语言接口传递指针时是如何工作的?

Question

我最近在尝试使用swig生成一个c语言项目的python接口，但是碰到一些指针传递的问题。以下是我的代码:

// swig_test.c
POINT *test() {
    POINT point; 
    point.x = 5;
    point.y = 2;
    //int r = point.x%point.y;
    printf("test\n");
    printf("point.x: %d, %d\n", point.x, &(point.x));
    printf("point.y: %d\n", point.y);
    printf("&point: %d\n\n", &point);
    return &point;
}

int test2(POINT *p)
{
    POINT point = *p;
    printf("p: %d, %d, %d\n", p, (*p).x, (*p).y);

    printf("test2\n");
    printf("point.x: %d, %d\n", (*p).x, point.x);
    printf("point.y: %d, %d\n", (*p).y, point.y);
    printf("point.x: %d\n", point.x);
    printf("point.y: %d\n", point.y);
    int r = 1; //point.x% point.y;
    return r;
}

int main()
{
    POINT *p = test();
    int r = test2(p);
    printf("%d", r);
}

// swig_test.h
#include <stdio.h>
#include <string.h>

struct POINT;
typedef struct POINT POINT;

struct POINT
{
    unsigned int x;
    unsigned int y;
};

POINT *test();
int test2(POINT *p);

// swig_test.i
 %module swig_test
 %{
 /* Put header files here or function declarations like below */
 #include "swig_test.h"
 extern POINT *test();
 extern int test2(POINT *p);
 %}

 %include "swig_test.h"
 extern POINT* test();
 extern int test2(POINT* p);

// main.py
import _swig_test as module
global point 
point = module.test()
print(module.test2(point))

当我只运行C的可执行文件版本时，输出是正确的:

test
point.x: 5, 2012281584
point.y: 2
&point: 2012281584

p: 2012281584, 5, 2
test2
point.x: 2012274424, 5
point.y: 0, 2
point.x: 5
point.y: 2
1

但是当我生成了pyd动态库并链接进python，指针传递进test2后所指向的值就发生了变化:

test
point.x: 5, 666825456
point.y: 2
&point: 666825456

p: 666825456, 666825496, 119
test2
point.x: 666825496, 666825496
point.y: 119, 119
point.x: 666825496
point.y: 119
1

由命令行可见，被传递的指针本身没有变化，但是所指向的值变了，请问这是为什么？难道python在结束test之后，所有变量已经都被释放了？

Answer 1

https://blog.csdn.net/u012247418/article/details/80260728