t_listen.3xti

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3XTI 代码 · 共 136 行

.TH t_listen 3xti
.SH Name
t_listen \- listen for a connect request 
.SH Syntax
.B #include <xti.h>
.br
.sp 1
.B int t_listen(\fIfd, call\fB)
.br
.B int \fIfd\fB;
.br
.B struct t_call \fI*call\fB;
.SH Arguments
.IP \fIfd\fR 10
Identifies the local transport endpoint where the connect indication
arrived.  
.IP \fIcall\fR 10
Contains information describing the connect indication. The \fIcall\fR
points to a \fBt_call\fR structure which contains the following members:
.EX
struct netbuf \fIaddr\fP;
struct netbuf \fIopt\fP;
struct netbuf \fIudata\fP;
int \fIsequence\fR;
.EE
.IP
The members of the \fBt_call\fR structure have the following meanings:
.RS 10
.IP \fIaddr\fP 12
Returns the protocol address of the calling transport user.
.IP \fIudata\fP 12
Returns any user data sent by the caller on the connect request.
.IP \fIsequence\fP 12
Identifies the returned connect indication with a  unique number. The value of \fIsequence\fR 
enables the user to listen for multiple connect indications before responding to any of them.
.RE
.IP
Because this function returns values for the \fIaddr\fR, \fIopt\fR, and
\fIudata\fR fields of \fIcall\fR, the \fImaxlen\fR field of each must be
set before issuing the 
.PN t_listen() 
to indicate the maximum size of the buffer for each.
.SH Description
This function listens for a connect request from a calling transport
user. The \fIfd\fR identifies the local transport endpoint where connect
indications arrive. On return, \fIcall\fR contains information
describing the connect indication.
.NXR "t_listen system call"
.NXR "connect request" "listening for"
.PP
By default, 
.PN t_listen 
executes in synchronous mode and waits for a
connect indiction to arrive before returning to the user. However, if
O_NONBLOCK is set by means of 
.PN t_open()
or
.PN fcntl()\fR,\fR 
.PN t_listen() 
executes asynchronously, reducing to a poll for existing connect indications. If none are 
available, it returns \-1 and sets 
.PN t_errno()
to [TNODATA].
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 4p
Parameters@Before Call@After Call
.sp 4p
_
.sp 6p
fd@x@/
call->addr.maxlen@x@/
call->addr.len@/@x
call->addr.buf@x@(x)
call->opt.maxlen@x@/
call->opt.len@/@x
call->opt.buf@x@(x)
call->udata.maxlen@x@/
call->udata.len@/@x
call->udata.buf@x@(?)
call->sequence@/@x
.sp 6p
_
.TE
.PP
.sp 12p
.SH Return Values
Upon successful completion, a value of 0 is returned. On failure, a
value of \-1 is returned, and \fBt_errno\fR is set to indicate the
error.
.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.
.TP 20 
[TOUTSTATE]
The function was issued in the wrong sequence on the transport endpoint
referenced by \fIfd\fR.
.TP 20
[TBADQLEN]
The \fIqlen\fR of the endpoint referenced by \fIfd\fR is zero.
.TP 20
[TBUFOVFLW]
The number of bytes allocated for an incoming argument is not sufficient
to store the value of that argument. The provider's state, as seen by
the user, changes to T_INCON, and the connect indication
information to be returned in \fIcall\fR is discarded. The value of
\fIsequence\fR returned can be used to do a 
.PN t_snddis()\fR.\fR
.TP 20
[TNODATA]
O_NONBLOCK was set, but no connect indications had been queued.
.TP 20
[TLOOK]
An asynchronous event has occurred on the transport endpoint and requires immediate attention.
.TP 20
[TNOTSUPPORT]
This function is not supported by the underlying transport provider. 
.TP 20
[TSYSERR]
A system error has occurred during execution of this function.
.SH See Also
fcntl(2),
t_accept(3xti),
t_alloc(3xti),
t_bind(3xti), 
t_connect(3xti),
t_open(3xti),
t_optmgmt(3xti), 
t_rcvconnect(3xti)