kevent and unix dgram socket problem
Robert Watson
rwatson at FreeBSD.org
Tue Apr 3 13:46:52 UTC 2007
On Tue, 3 Apr 2007, Jason Carroll wrote:
> // create the local address, bind & listen
> struct sockaddr_un addr;
> memset(&addr, 0, sizeof(addr));
> addr.sun_family = AF_LOCAL;
> strncpy(addr.sun_path, "usock", UN_PATH_LEN - 1);
> assert(bind(fd, (sockaddr*) &addr, sizeof(sockaddr_un)) == 0);
> assert(listen(fd, LISTENQ) == 0);
Try dropping the listen() call. This is only required for stream sockets
where you will then accept() new connections (returning new sockets).
listen() should probably be returning an error, and apparently isn't. What
may be happening is that as of the point where listen() is called, future
attempts to register kevents for "read" will be set up to detect whether
accept() will return a socket or not, not whether there is data in the socket
listen() has been called on.
I'll investigate adding a check so that an error would have been returned
here. This relates to another bug we have, in which if you register a kqueue
event for "read" on a TCP socket before calling listen(), then the result is
very different from what happens if you register the kqueue event after
listen().
Robert N M Watson
Computer Laboratory
University of Cambridge
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