写一个 epoll 的服务端程序

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <arpa/inet.h>#include <sys/epoll.h>#include <fcntl.h>
#define BUF_SIZE 4#define EPOLL_SIZE 50
int setNonBlockingMode(int fd) {    int flag = fcntl(fd, F_GETFL, 0);    fcntl(fd, F_SETFL, flag | O_NONBLOCK);    return 0;}
void errorHandling(const char *message) {    fputs(message, stderr);    fputc('\n', stderr);    exit(1);}
int main(int argc, char *argv[]) {    int servSock, clntSock;    struct sockaddr_in servAddr, clntAddr;    socklen_t clntAddrSize;    char buf[BUF_SIZE];    struct epoll_event *epEvents;    struct epoll_event event;    int epfd, eventCnt, i;
    if (argc != 2)        errorHandling("Usage: ./server <port>");
    servSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);    if (servSock == -1)        errorHandling("socket() error");
    memset(&servAddr, 0, sizeof(servAddr));    servAddr.sin_family = AF_INET;    servAddr.sin_addr.s_addr = htonl(INADDR_ANY);    servAddr.sin_port = htons(atoi(argv[1]));
    if (bind(servSock, (struct sockaddr *) &servAddr, sizeof(servAddr)) == -1)        errorHandling("bind() error");
    if (listen(servSock, 5) == -1)        errorHandling("listen() error");
    epfd = epoll_create(EPOLL_SIZE);    epEvents = malloc(sizeof(struct epoll_event) * EPOLL_SIZE);
    event.events = EPOLLIN;    event.data.fd = servSock;    epoll_ctl(epfd, EPOLL_CTL_ADD, servSock, &event);
    while (1) {        eventCnt = epoll_wait(epfd, epEvents, EPOLL_SIZE, -1);        if (eventCnt == -1)            errorHandling("epoll() error");
        for (i = 0; i < eventCnt; ++i) {            if (epEvents[i].data.fd == servSock) {                clntAddrSize = sizeof(clntAddr);                clntSock = accept(servSock, (struct sockaddr *) &clntAddr, &clntAddrSize);                setNonBlockingMode(clntSock);
                event.events = EPOLLIN | EPOLLET;                event.data.fd = clntSock;                epoll_ctl(epfd, EPOLL_CTL_ADD, clntSock, &event);                printf("Connected client: %d\n", clntSock);            } else {                while (1) {                    int strLen = read(epEvents[i].data.fd, buf, BUF_SIZE);                    if (strLen == 0) {                        epoll_ctl(epfd, EPOLL_CTL_DEL, epEvents[i].data.fd, NULL);                        close(epEvents[i].data.fd);                        printf("Closed client: %d\n", epEvents[i].data.fd);                        break;                    } else if (strLen < 0) {                        if (errno == EAGAIN)                            break;                        errorHandling("read() error");                    } else {                        write(epEvents[i].data.fd, buf, strLen);                    }                }            }        }    }
    close(servSock);    close(epfd);    return 0;}