Hi!

At Sun, 31 Jul 2011 14:40:10 +0900, SATOH Fumiyasu wrote:

I've regenerated the patch with 'hg export' instead of 'hg log -p'. (Sorry, I'm a Mercurial newbie.)

At Sun, 31 Jul 2011 01:41:22 +0900, SATOH Fumiyasu wrote:

...

Dovecot ignores EINPROGRESS on connect(2) for non-blocking fd. This is wrong. After that, read(2) to fd (or write(2) to fd) fails with ENOTCONN if the connection of fd is not completed.

The attached patch fixes this problem.

Any comment?

On a high-load Solaris 10 box, dovecot-lda fails to query (I/O) to dovecot dict socket with ENOTCONN. My patch fixes this problem.

Regards,

-- -- Name: SATOH Fumiyasu (fumiyas @ osstech co jp) -- Business Home: http://www.OSSTech.co.jp/ -- Personal Home: http://www.SFO.jp/blog/

At Wed, 10 Aug 2011 20:37:46 +0300, Timo Sirainen wrote:

On 2.8.2011, at 5.25, SATOH Fumiyasu wrote:

...

...

...

Dovecot ignores EINPROGRESS on connect(2) for non-blocking fd. This is wrong. After that, read(2) to fd (or write(2) to fd) fails with ENOTCONN if the connection of fd is not completed.

The attached patch fixes this problem.

If you do that, then there's no point in making the socket non-blocking before connect().

Linux connect(2) manpage said:

   EINPROGRESS
          The socket is nonblocking and the connection
          cannot be completed immediately.  It is pos-
          sible to select(2) or poll(2) for completion
          by  selecting the socket for writing.  After
          select(2) indicates  writability,  use  get-
          sockopt(2)  to  read  the SO_ERROR option at
          level SOL_SOCKET to determine  whether  con-
          nect()  completed  successfully (SO_ERROR is
          zero) or unsuccessfully (SO_ERROR is one  of
          the  usual error codes listed here, explain-
          ing the reason for the failure).

Solaris 10 connect(3SOCKET) manpage said:

   EINPROGRESS             The socket is non-blocking,
                           and  the  connection cannot
                           be  completed  immediately.
                           You  can use  select(3C) to
                           complete the connection  by
                           selecting  the  socket  for
                           writing.

Windows connect function document said (http://msdn.microsoft.com/en-us/library/ms737625%28v=vs.85%29.aspx):

With a nonblocking socket, the connection attempt cannot be completed immediately. In this case, connect will return SOCKET_ERROR, and WSAGetLastError will return WSAEWOULDBLOCK. In this case, there are three possible scenarios:

* Use the select function to determine the completion of the
  connection request by checking to see if the socket is writeable.
* If the application is using WSAAsyncSelect to indicate interest
  in connection events, then the application will receive an
  FD_CONNECT notification indicating that the connect operation is
  complete (successfully or not).
* If the application is using WSAEventSelect to indicate interest
  in connection events, then the associated event object will be
  signaled indicating that the connect operation is complete
  (successfully or not).

...

On a high-load Solaris 10 box, dovecot-lda fails to query (I/O) to dovecot dict socket with ENOTCONN. My patch fixes this problem.

I think Linux/etc returns EAGAIN in such situation. Maybe the right fix is to just add EINPROGRESS check for net_connect_unix_with_retries()? (With some extra changes so that it actually sees that errno from net_connect_unix())

I think you MUST wait for the fd to complete connect() before read() from / write() to the fd in such situation.

-- -- Name: SATOH Fumiyasu (fumiyas @ osstech co jp) -- Business Home: http://www.OSSTech.co.jp/ -- Personal Home: http://www.SFO.jp/blog/