从共享库调用函数 [英] Calling functions from a shared library

问题描述

我试图从共享库的函数中调用核心"函数，但我得到:

I'm trying to call a "core" function from a shared library's function but I get:

./a.out: symbol lookup error: ./libtest.so: undefined symbol: testf

我使用的代码非常基础，因为我刚刚开始编写共享库，并且仅用于测试目的:main.h

The code I'm using is very basic because I'm just getting into writing shared libraries and it's just for testing purposes: main.h

extern void testf();

main.c

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

extern void testf()
{
    printf("bla bla\n");
}

int main () {

void *handle = NULL;
void (*testlib)(void) = NULL;

handle = dlopen("./libtest.so" ,RTLD_LAZY);
testlib = dlsym(handle, "testfunc");

if ( testlib == NULL ) 
{
    printf("Error: %s \n", dlerror());
}
else 
{
    testlib();
}
}

libtest.c

#include <stdio.h>
#include "main.h"

void testfunc() {

printf("Test plugin\n");
testf();
}

以及我用来编译它的命令:

And the commands I compile it with:

gcc -fPIC -g -c -Wall libtest.c
gcc -shared -Wl,-soname,libtest.so.1 -o libtest.so libtest.o -lc
gcc main.c -ldl

有可能实现吗?试图找到答案，但真的不知道如何正确地形成问题，以便我可以更好地搜索它.

Is it possible to achieve this? Tried to find the answer, but don't really know how to form the question right so I can search better for it.

谢谢！

推荐答案

抱歉，找到了答案:我在编译主程序时使用了错误的参数，应该使用:

Sorry, managed to find the answer: I was compiling the main program with wrong parameters, should use:

gcc main.c -ldl -rdynamic

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