Readme/C/9、动态库加载/概述.md

//
// Created by 诸葛温侯 on 2023/9/27.
//

#ifndef JIANGHUKE_SERVICE_GATE_H
#define JIANGHUKE_SERVICE_GATE_H

class ServiceGate {
public:
    ServiceGate();

    void create();
};

#endif //JIANGHUKE_SERVICE_GATE_H

//
// Created by 诸葛温侯 on 2023/9/25.
//
#include "service_gate.h"
#include <iostream>

ServiceGate::ServiceGate() = default;

void ServiceGate::create() {
    std::cout << "haha" << std::endl;
}

// 导出create函数
extern "C" {
void create() {
    ServiceGate gate;
    gate.create();
}
}

#include <iostream>

#ifndef WIN32

#include <dlfcn.h>

#   define OPEN_LIBRARY(libName) dlopen(libName, RTLD_NOW | RTLD_GLOBAL)
#   define CLOSE_LIBRARY(handle) dlclose(handle)
#   define GET_SYMBOL(handle, symName) dlsym(handle, symName)
#   define GET_ERROR() dlerror()
#else

#include <winsock2.h>
#include <Windows.h>

#ifdef UNICODE
#   define OPEN_LIBRARY(libName) LoadLibraryW(libName)
#else
#   define OPEN_LIBRARY(libName) LoadLibraryA(libName)
#endif

#   define CLOSE_LIBRARY(handle) FreeLibrary(static_cast<HMODULE>(handle))
#   define GET_SYMBOL(handle, symName) GetProcAddress(static_cast<HMODULE>(handle), symName)
#   define GET_ERROR() "Windows error"

#endif

struct module {
    void (*create)();
};

int main(int argc, char *argv[]) {
    void *libraryHandle = OPEN_LIBRARY("./service_gate.so");
    if (libraryHandle == nullptr) {
        // 动态库加载失败
        const char *error = GET_ERROR();
        std::cout << error << std::endl;
    }

    // 获取create函数指针
    typedef void (*CreateFunc)();
    auto create = reinterpret_cast<CreateFunc>(GET_SYMBOL(libraryHandle, "create"));

    if (create == nullptr) {
        // 获取函数指针失败
        const char *error = GET_ERROR();
        std::cout << error << std::endl;
    }

    module mod{};
    mod.create = create;

    mod.create();


    CLOSE_LIBRARY(libraryHandle);
    return 0;

}