t_sndudata.3xti

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3XTI 代码 · 共 132 行

.TH t_sndudata 3xti
.SH Name
t_sndudata \- send a data unit
.SH Syntax
.B #include <xti.h>
.br
.sp 1
.B int t_sndudata(\fIfd, unitdata\fB)
.br
.B int \fIfd\fB;
.br
.B struct t_unitdata \fI*unitdata\fB;
.SH Arguments
.IP \fIfd\fR 10
Identifies the local transport endpoint through which data will be sent.
.IP \fIunitdata\fR 10
Points to a \fBt_unitdata\fR structure containing the following members:
.EX
struct netbuf \fIaddr\fP;
struct netbuf \fIopt\fP;
struct netbuf \fIudata\fR;
.EE
.IP 
The members have the following meanings:
.RS 10
.IP \fIaddr\fP 12
Specifies the protocol address of the destination user.
.IP \fIopt\fP	
Identifies protocol-specific options that the user wants associated with the request.
.IP \fIudata\fP
Specifies the user data to be sent.
.RE
.SH Description
This function is used in connectionless mode to send a data unit to
another transport user.
.NXR "t_sndudata system call"
.NXR "connectionless mode" "sending data"
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 6p
Parameters@Before Call@After Call
.sp 6p
_
.sp 6p
fd@x@/
unitdata->addr.maxlen@/@/
unitdata->addr.len@x@/
unitdata->opt.maxlen@/@/
unitdata->opt.len@x@/
unitdata->opt.buf@?(?)@/
unitdata->udata.maxlen@/@/
unitdata->udata.len@x@/
unitdata->udata.buf@x(x)@/
.sp 6p
_
.TE
.PP
.sp 12p
.sp 2
If the \fIlen\fR field of \fIudata\fR is zero, and sending of zero
octets is not supported by the underlying transport service, the
.PN t_sndudata() 
returns \-1 with \fBt_errno\fR set to [TBADDATA].
.PP
By default, 
.PN t_sndudata()
operates in synchronous mode and may wait if
flow control restrictions prevent the data from being accepted by the
local transport provider at the time the call is made. However, if
O_NONBLOCK is set by means of 
.PN t_open() 
or 
.PN fcntl(),
.PN t_sndudata()
executes in asynchronous mode and fails under such
conditions. The process can arrange to be notified of the clearance of a
flow control restriction by means of 
.PN t_look()\fR.\fR 
.PP
If the amount of data specified in \fIudata\fR exceeds the TSDU size as
returned in the \fItsdu\fR field of the \fIinfo\fR argument of
.PN t_open() 
or 
.PN t_getinfo(), 
the provider generates a protocol error. See [TSYSERR] under the DIAGNOSTICS
section. If 
.PN t_sndudata()
is issued before the destination user has activated its transport endpoint, 
the data unit can be discarded.
.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
[TFLOW]
O_NONBLOCK was set, but the flow control mechanism prevented the
transport provider from accepting any data at this time.
.TP 20
[TBADDATA]
Illegal amount of data; zero octets are not supported.
.TP 20
[TLOOK]
An asynchronous event has occurred on the transport endpoint.
.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. A
protocol error cannot cause 
.PN t_sndudata()
to fail until a subsequent access of the transport endpoint.
.SH See Also
fcntl(2), 
t_alloc(3xti), 
t_open(3xti),
t_rcvudata(3xti), 
t_rcvuderr(3xti)