举例说明linux poll服务端和客户端代码

好的，下面是一个简单的使用poll实现的服务端和客户端代码：

服务端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <poll.h>

#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    int server_fd, client_fds[MAX_CLIENTS], max_fd, activity, i, valread, sd;
    struct sockaddr_in address;
    char buffer[BUFFER_SIZE] = {0};
    struct pollfd fds[MAX_CLIENTS + 1];

    // 创建socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置socket选项
    int opt = 1;
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }

    // 绑定地址和端口
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(8080);
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听socket
    if (listen(server_fd, 3) < 0) {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    // 初始化pollfd数组
    memset(fds, 0, sizeof(fds));
    fds[0].fd = server_fd;
    fds[0].events = POLLIN;
    for (i = 1; i < MAX_CLIENTS + 1; i++) {
        fds[i].fd = -1;
    }

    // 循环等待客户端连接
    while (1) {
        // 调用poll函数等待事件
        activity = poll(fds, MAX_CLIENTS + 1, -1);
        if (activity < 0) {
            perror("poll failed");
            exit(EXIT_FAILURE);
        }

        // 处理server_fd的事件
        if (fds[0].revents & POLLIN) {
            int new_socket;
            if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
                perror("accept failed");
                exit(EXIT_FAILURE);
            }

            // 将新连接的socket加入到fds数组中
            for (i = 1; i < MAX_CLIENTS + 1; i++) {
                if (fds[i].fd == -1) {
                    fds[i].fd = new_socket;
                    fds[i].events = POLLIN;
                    break;
                }
            }
        }

        // 处理客户端socket的事件
        for (i = 1; i < MAX_CLIENTS + 1; i++) {
            sd = fds[i].fd;

            if (sd > 0 && fds[i].revents & POLLIN) {
                if ((valread = read(sd, buffer, BUFFER_SIZE)) == 0) {
                    // 客户端关闭连接
                    close(sd);
                    fds[i].fd = -1;
                } else {
                    // 处理客户端发送的数据
                    buffer[valread] = '\0';
                    printf("Received message: %s\n", buffer);
                    send(sd, buffer, strlen(buffer), 0);
                }
            }
        }
    }

    return 0;
}

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    int sock = 0, valread;
    struct sockaddr_in serv_addr;
    char buffer[BUFFER_SIZE] = {0};

    // 创建socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("\n Socket creation error \n");
        return -1;
    }

    // 设置服务器地址和端口
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(8080);
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }

    // 连接服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        printf("\nConnection Failed \n");
        return -1;
    }

    // 发送数据
    char *hello = "Hello from client";
    send(sock, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    // 接收数据
    valread = read(sock, buffer, BUFFER_SIZE);
    printf("%s\n", buffer);

    return 0;
}