libevent file文件读取事件

最新推荐文章于 2025-05-12 13:22:50 发布

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#libevent #O_RDONLY

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#include <iostream>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <event2/event.h>

using namespace std;


static void READ_CB(int sock, short which , void* arg)
{
    char szBuff[1024];
    memset(szBuff, 0, sizeof(szBuff));
    
    int rd_len = read(sock, szBuff, sizeof(szBuff)-1);
    if (rd_len > 0)
    {
        cout<<szBuff<<endl;
    }
    
}
int main()
{
    //初始化配置上下文
    event_config *pevconf = event_config_new();
    if (!pevconf)
    {
        cerr<<"event_config_new error"<<endl;
        return -1;
    }
    //EV_FEATURE_FDS：需要一个允许文件描述符和套接字的事件方法
    event_config_require_features(pevconf, EV_FEATURE_FDS);
    event_base *pevbs = event_base_new_with_config(pevconf);
    if (!pevbs)
    {
        cerr<<"event_base_new_with_config error"<<endl;
        return -1;
    }
    
    //以非阻塞性读取打开系统文件
    int sock = open("/var/log/auth.log", O_RDONLY | O_NONBLOCK, 0);
    
    //将sock文件移动到文件末尾，否则会从文件开头开始读取
    lseek(sock, 0, SEEK_END);
    //文件读取、持久性事件
    event* pevf = event_new(pevbs, sock, EV_READ|EV_PERSIST, READ_CB, event_self_cbarg());
    if (!pevf)
    {
        cerr<<"event_new error"<<endl;
    }
    event_add(pevf, NULL);
    
    event_base_dispatch(pevbs);
    event_config_free(pevconf);
    event_base_free(pevbs);
    return 0;
}

可以进行linux终端登陆来进行测试
./event_file
Feb 5 01:29:31 ubuntu1 sshd[17635]: Accepted password for zhangsan from 192.168.202.1 port 52975 ssh2
Feb 5 01:29:31 ubuntu1 sshd[17635]: pam_unix(sshd:session): session opened for user zhangsan by (uid=0)

Feb 5 01:29:31 ubuntu1 systemd-logind[910]: New session 506 of user zhangsan.

Feb 5 01:31:09 ubuntu1 sshd[17635]: pam_unix(sshd:session): session closed for user zhangsan

Feb 5 01:31:09 ubuntu1 systemd-logind[910]: Removed session 506.