closing non-blocking socket

Question

I have the following code in C.

void setNonBlocking(SOCKET fd){
    int flags;
    if (-1 == (flags = fcntl(fd, F_GETFL, 0)))
        flags = 0;

    fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}

int main(){

int sock;
connect(sock, .....);
setNonBlocking(sock);
....
close(sock);

//we will do something here but the application exits in/after the close operation

}

I am using the socket in non-blocking mode with setNonBlocking function. When i close socket, the application immediately exits without segfault or anything else. I don't see this issue if i don't use setNonBlocking function.

How can i close the non-blocking socket without this issue?

Run your code under GDB. The behavior you're describing (close causing application exit without crash) is pretty much impossible. — diciu
Have you created a socket using the socket() function? This is missing in your code. You declare sock (which at this point contains garbage or 0) and then you call connect. — Frunsi
Can you explain more about how you do send/receive etc in your code? That might be more helpful. Normally close should not behave differently just because the socket is non-blocking. — Jay

nos nos · Accepted Answer · 2009-12-29T10:40:26

Perhaps your application is getting SIGPIPE. You should normally handle or ignore the SIGPIPE signal when programming with sockets.

closing non-blocking socket

2 Answers