t_sync.3xti

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3XTI 代码 · 共 108 行

.TH t_sync 3xti
.SH Name
t_sync \- synchronize transport library 
.SH Syntax
.B #include <xti.h>
.br
.sp 1
.B int t_sync(\fIfd\fB)
.br
.B int \fIfd\fB;
.SH Arguments
.IP \fIfd\fR 10
Identifies the local transport endpoint. 
.SH Description
For the transport endpoint specified by \fIfd\fR, 
.PN t_sync()
synchronizes the data structures managed by the transport library with
information from the underlying transport provider. In doing so, 
.PN t_sync()
can convert an uninitialized file descriptor to an initialized transport endpoint, by
updating and allocating the necessary library data structures. The file descriptor, which is
assumed to have referenced a transport endpoint, has to be obtained by means of an
.PN open()\fR,\fR
.PN dup()\fR,\fR
or be the result of a fork and
.PN exec()\fR.\fR
The function also allows two
cooperating processes to synchronize their interaction with a transport
provider.
.NXR "t_sync system call"
.NXR "transport library" "synchronizing"
.PP
For example, if a process forks a new process and issues an
.PN exec()\fR,\fR 
the new process must issue a 
.PN t_sync() 
to build the
private library data structure associated with a transport endpoint and
to synchronize the data structure with the relevant provider
information.
.PP
It is important to remember that the transport provider treats all users
of a transport endpoint as a single user. If multiple processes are
using the same endpoint, they should coordinate their activates so as not
to violate the state of the transport endpoint. The 
.PN t_sync()
function returns the current state of the transport endpoint to the
user, thereby enabling the user to verify the state before taking
further action. This coordination is valid only among cooperating
processes; it is possible that a process or an incoming event could
change the endpoint's state after a 
.PN t_sync() 
is issued.
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 6p
Parameters@Before Call@After Call
.sp 6p
_
.sp 6p
fd@x@/
.sp 6p
_
.TE
.PP
.sp 12p
.SH Return Values
Upon successful completion, 
.PN t_sync
returns the state of the
transport endpoint. On failure, a value of \-1 is returned, and \fBt_errno\fR 
is set to indicate the error. The state returned is one of the
following:
.IP \fBT_IDLE\fP 10
Idle
.IP \fBT_OUTCON\fP
Outgoing connection pending
.IP \fBT_INCON\fP
Incoming connection pending
.IP \fBT_DATAXFER\fP
Data transfer
.IP \fBT_OUTREL\fP
Outgoing orderly release (waiting for an orderly release indication).
.IP \fBT_INREL\fP
Incoming orderly release (waiting for an orderly release request) 
.SH Diagnostics
On failure, \fBt_errno\fR is set to one of the following:
.TP 20
[TBADF]
The specified file descriptor does not refer to a transport endpoint.
This error may be returned when the \fIfd\fR has been previously closed
or an erroneous number may have been passed to the call.
.TP 20 
[TSTATECHNG]
The transport endpoint is undergoing a state change.
.TP 20
[TSYSERR]
A system error has occurred during execution of this function.
.SH See Also
dup(2), 
exec(2), 
fork(2), 
open(2)