Fix network poll() issue: don't interrupt poll if socket not connected. Listen sockets are not connected and the poll() is waiting for connection events.

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5717 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 17 insertions, 2 deletions

diff --git a/nuttx/net/net_poll.c b/nuttx/net/net_poll.c
index 1838f541e..583d469a7 100644
--- a/nuttx/net/net_poll.c
+++ b/nuttx/net/net_poll.c
@@ -253,9 +253,24 @@ static inline int net_pollsetup(FAR struct socket *psock,
       fds->revents |= (POLLOUT & fds->events);
     }
 
-  /* Check for a loss of connection events */
+  /* Check for a loss of connection events.  We need to be careful here.
+   * There are four possibilities:
+   *
+   * 1) The socket is connected and we are waiting for data availability
+   *    events.
+   * 2) This is a listener socket that was never connected and we are
+   *    waiting for connection events.
+   * 3) This socket was previously connected, but the peer has gracefully
+   *    closed the connection.
+   * 4) This socket was previously connected, but we lost the connection
+   *    due to some exceptional event.
+   *
+   * We can detect 1) and 3), but 2) and 4) appear the same.  So we
+   * do the best we can for now:  We will report POLLHUP if the socket
+   * has been gracefully closed.
+   */
 
-  if (!_SS_ISCONNECTED(psock->s_flags))
+  if (_SS_ISCLOSED(psock->s_flags))
     {
       fds->revents |= (POLLERR | POLLHUP);
     }