如何使用epoll机制实现ubus下的notify发送消息和register接受消息 写出代码

下面是一个使用 epoll 机制实现 ubus 下的 notify 发送消息和 register 接收消息的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/epoll.h>
#include <libubox/blobmsg_json.h>
#include <libubus.h>

#define MAX_EVENTS 10

int main(int argc, char *argv[]) {
    int epoll_fd, ubus_fd, n;
    struct epoll_event event, events[MAX_EVENTS];
    struct ubus_context *ctx;
    struct ubus_request req;
    
    // 初始化 ubus 对象
    ctx = ubus_connect(NULL);
    if (!ctx) {
        fprintf(stderr, "Failed to connect to ubus\n");
        return -1;
    }
    
    // 创建 epoll 对象
    epoll_fd = epoll_create1(0);
    if (epoll_fd == -1) {
        fprintf(stderr, "Failed to create epoll object\n");
        ubus_free(ctx);
        return -1;
    }
    
    // 注册消息接收回调函数
    ubus_fd = ubus_get_fd(ctx);
    event.events = EPOLLIN;
    event.data.fd = ubus_fd;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, ubus_fd, &event) == -1) {
        fprintf(stderr, "Failed to register ubus_fd to epoll\n");
        close(epoll_fd);
        ubus_free(ctx);
        return -1;
    }
    
    // 发送消息
    memset(&req, 0, sizeof(req));
    req.path = "/ubus/path";
    req.method = "method_name";
    req.args = blobmsg_new_array();
    blobmsg_add_string(req.args, NULL, "arg1");
    blobmsg_add_string(req.args, NULL, "arg2");
    ubus_invoke_async(ctx, &req, &req.req_id);
    event.events = EPOLLIN;
    event.data.fd = req.req_id;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, req.req_id, &event) == -1) {
        fprintf(stderr, "Failed to register request event to epoll\n");
        close(epoll_fd);
        ubus_free(ctx);
        return -1;
    }
    
    // 等待事件发生并处理事件
    while (1) {
        n = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
        if (n == -1) {
            fprintf(stderr, "Failed to wait for events\n");
            close(epoll_fd);
            ubus_free(ctx);
            return -1;
        }
        
        for (int i = 0; i < n; i++) {
            if (events[i].data.fd == ubus_fd) {
                ubus_handle_event(ctx);
            } else {
                ubus_complete_request(ctx, events[i].data.fd);
            }
        }
    }
    
    // 释放资源
    blobmsg_free(req.args);
    close(epoll_fd);
    ubus_free(ctx);
    return 0;
}

以上代码仅供参考，具体实现方式需要根据具体需求进行调整。