C - dlopen dlsym

 

 

-----------------------------------------------------------------------------dlsym-----------------------------------------------------------------------------

測試dlsym打開的函數指針能不能屢次調用

#include <stdio.h>
#include <dlfcn.h>
#include <unistd.h>
#include <time.h>

int main(){
int (*func)(int a, int b);
void *handle = NULL;
int c;
    char *myso = "./mylib.so";
        if((handle = dlopen(myso, RTLD_NOW)) != NULL) {
            printf("success\n");
            func = (void(*)())dlsym(handle, "add");
            if(func != NULL){c=(*func)(1,2);}
            printf("1--%d",c);
            if(func != NULL){c=(*func)(2,2);}
             printf("\n2--%d",c);
            dlclose(handle);
        }
                            else printf("dlopen - %s\n", dlerror());
}

gcc main.c -ldl -rdynamic

 

#include <stdlib.h>
#include <stdio.h>


int add(int a,int b){
 return a+b;
}

gcc -fPIC -shared -o mylib.so add.c

 

調用：

./a.out

執行結果：