CONNLD(4M) STREAMS Modules CONNLD(4M)
NAME
connld - line discipline for unique stream connections
SYNOPSIS
int ioctl(fd, I_PUSH, "connld");
DESCRIPTION
connld is a STREAMS-based module that provides unique connections between
server and client processes. It can only be pushed (see
streamio(4I))
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(4I)) 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
creat(2).
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.
ERRORS
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
M_HANGUP message is at the stream head of the pipe onto
which
connld is being pushed.
EAGAIN Internal data structures could not be allocated.
ENFILE A file table entry could not be allocated.
SEE ALSO
creat(2),
open(2),
fattach(3C),
streamio(4I) STREAMS Programming Guide June 19, 2021
CONNLD(4M)