note

相关系统调用接口：dlopen\dlclose\dlerror\dlsym

code

 math.c

int add(int x, int y) {
    return (x+y);
}

int sub(int x, int y) {
    return (x-y);
}

main.c

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

int main(int argc, char** argv) {
    void* handle = NULL;
    int x = 22;
    int y = 33;
    handle = dlopen(argv[1], RTLD_NOW);
    if (handle == NULL) {
        printf("dll load error\n");
        printf("%s\n", dlerror());
        fflush(stdout);
        exit(1);
    }
    printf("dll load success\n");
    void* f = dlsym(handle, "add");
    if (f == NULL) {
        printf("dlsym return NULL\n");
        printf("%s\n", dlerror());
        fflush(stdout);
        dlclose(handle);
        exit(1);
    }
    int (*fun)(int,int) = f;
    printf("%d+%d=%d\n", x,y,fun(x,y));
    fflush(stdout);
    dlclose(handle);
    exit(0);
}

makefile

default:
	gcc -c math.c -o math.o
	gcc -shared -fPIC -o libmath.so math.o
	export LD_LIBRARY_PATH=.
	gcc main.c -L. -o main.exe -ldl -lmath

test