Question

我越来越难以在epoll_event中使用void * ptr。我可以将它链接到一个结构？例如，我可以这样做吗？因为我正在尝试这样的东西，但它不起作用，监听套接字上的第一个循环是好的，但在另一个事件进入后崩溃。有人可以帮助我理解如何使用data.ptr？

struct client { 
int fd; 
int connection_status;
};

struct epoll_event *events = NULL;
struct epoll_event ev;
struct client *c = new client;
struct client *event_c = NULL;

c.fd = (socket);

int efd = epoll_create1(0);
ev.data.fd = c.fd;
ev.events = EPOLLIN;
ev.data.ptr = c;
epoll_ctl ( efd , EPOLL_CTL_ADD , c.fd , &ev );

events = (struct epoll_event*)calloc ( XXX , sizeof event );

while(1) {
    int n = epoll_wait ( efd , events , XXX , -1 ); 
    for ( int i = 0 ; i  < n ; i++ ) {
        event_c = (struct client*) events[i].data.ptr;
        cout << "SOCKET: " << event_c->fd << endl;

        if (c->fd == events[i].data.fd ) {
            struct client *new_c = new client;
            struct epoll_event new_ev;
            struct sockaddr inaddr;
            sockletn_t in_len;
            int nfd = accept ( c->fd , &inaddr , &in_len );
            /* make socket non-blocking ... / error checking */
            new_c->fd = nfd;
            new_c->connection_status = 1;
            new_ev.data.fd = nfd;
            new_ev.events = EPOLLIN;
            new_ev.data.ptr = client;
            int r = epoll_ctl ( efd , EPOLL_CTL_ADD , nfd , &new_ev );
            continue;
         } else {
            ssize_t count;
            char buf[512];
            int count = read ( events[i].data.fd , buf , sizeof buf );
            // ... error checking blah blah blah

            int rc = write ( 1 , buf , count );
        }
    }
}

Answer 1

void *ptr和int fd都位于struct epoll_event内的联合内。你应该使用其中任何一个而不是两个。因此，在您的结构中，同时添加fd的字段，并且只将指针链接到ptr的{{1}}字段中的结构。这样当你拿回指针然后从中获取epoll_event以供进一步使用。

如何使用epoll_event data.ptr

1 个答案: