V8/usr/man/man4/connld.4

.TH CONNLD 4
.SH NAME
connld \- unique stream connection
.SH DESCRIPTION
This stream module (see
.IR stream (4))
is used to provide unique connections
to a server.
The file descriptor
.I fd
should refer to an end of a stream\-usually a pipe\-that
will subsequently be mounted onto a file by
.IR gmount (2).
When an
.IR open
or
.IR creat (2)
call is applied to a stream-associated file with this module installed,
a new pipe is created internally.
A message identical to that described for the
FIOSNDFD
request (see
.IR stream (4))
is sent along the stream to the process
at the other end.
This process must respond in one of these ways:
it may simply write some data, or reply with
.LP
	ioctl(fd1, FIOACCEPT, (char *)NULL);
.LP
Then the attempt to open the stream succeeds,
and the returned file descriptor refers to the new pipe,
whose other end is held by the server process.
It may also respond by passing a new file descriptor,
using
.LP
	ioctl(fd1, FIOSNDFD, &fd2);
.LP
Then the local end of the internally-created pipe is discarded, and
the returned file descriptor refers to the transmitted file.
.PP 
On the other hand, if the server process closes the transmitted file descriptor,
or does
.LP
	ioctl(fd1, FIOREJECT, (char *)NULL);
.LP
then the attempt to open fails.
.PP
Finally, if the entity, whether process or device, that receives
the FIOSNDFD message fails to respond in some appropriate way,
the process attempting to open the file will wait until it is sent
a signal, or the system is rebooted, or the end of eternity,
whichever comes first.