connld - line discipline for unique stream connections
connld is a STREAMS-based module that provides unique con-
nections between server and client processes. It can only be
pushed (see streamio(7I)) onto one end of a STREAMS-based
pipe that may subsequently be attached to a name in the file
system name space with
fattach(3C). 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 I_SENDFD (see
streamio(7I)) 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 I_SENDFD request by accepting
the file descriptor through the I_RECVFD 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
If the server does not respond to the I_SENDFD 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 I_RECVFD request is
issued. If the server process exits before issuing the
I_RECVFD request, the open(2) or the creat(2) invocation
will fail and return -1 to the originating process.
When the connld module is pushed onto a pipe, it ignores
messages going back and forth through the pipe.
On success, an open of connld returns 0. On failure, errno
is set to the following values:
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.
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.
An internal pipe could not be created.
ENXIO An M_HANGUP message is at the stream head of the pipe
onto which connld is being pushed.
Internal data structures could not be allocated.
A file table entry could not be allocated.
creat(2), open(2), fattach(3C), streamio(7I)
STREAMS Programming Guide
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