connld(7)                                                         connld(7)


   NAME
         connld - line discipline for unique stream connections

   DESCRIPTION
         connld is a STREAMS-based module that provides unique connections
         between server and client processes.  It can only be pushed [see
         streamio(7)] onto one end of a STREAMS-based pipe that may
         subsequently be attached to a name in the file system name space.
         After the pipe end is attached, a new pipe is created internally when
         an originating process attempts to open(2) or creat(2) the file
         system name.  A file descriptor for one end of the new pipe is
         packaged into a message identical to that for the ioctl ISENDFD [see
         streamio(7)] and is transmitted along the stream to the server
         process on the other end.  The originating process is blocked until
         the server responds.

         The server responds to the ISENDFD request by accepting the file
         descriptor through the IRECVFD ioctl message.  When this happens,
         the file descriptor associated with the other end of the new pipe is
         transmitted to the originating process as the file descriptor
         returned from open(2) or creat(2).

         If the server does not respond to the ISENDFD request, the stream
         that the connld module is pushed on becomes uni-directional because
         the server will not be able to retrieve any data off the stream until
         the IRECVFD request is issued.  If the server process exits before
         issuing the IRECVFD request, the open(2) or the creat(2) system
         calls will fail and return -1 to the originating process.

         When the connld module is pushed onto a pipe, messages going back and
         forth through the pipe are ignored by connld.

         On success, an open of connld returns 0.  On failure, errno is set to
         the following values:

         EINVAL       A stream onto which connld is being pushed is not a pipe
                      or the pipe does not have a write queue pointer pointing
                      to a stream head read queue.

         EINVAL       The other end of the pipe onto which connld is being
                      pushed is linked under a multiplexor.

         EPIPE        connld is being pushed onto a pipe end whose other end
                      is no longer there.

         ENOMEM       An internal pipe could not be created.

         ENXIO        An MHANGUP message is at the stream head of the pipe
                      onto which connld is being pushed.




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   connld(7)                                                         connld(7)


         EAGAIN       Internal data structures could not be allocated.

         ENFILE       A file table entry could not be allocated.

   SEE ALSO
         streamio(7)
         Programmer's Guide: STREAMS














































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