t_optmgmt.3xti

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3XTI 代码 · 共 151 行

.TH t_optmgmt 3xti
.SH Name
t_optmgmt \- manage options for a transport endpoint 
.SH Syntax
.B #include <xti.h>
.br
.sp 1
.B int t_optmgmt(\fIfd, req, ret\fB)
.br
.B int \fIfd\fB;
.br
.B struct t_optmgmt \fI*req\fB;
.br
.B struct t_optmgmt \fI*ret\fB;
.SH Arguments
.IP \fIfd\fR 10
Identifies a bound transport endpoint.
.IP \fIreq\fR 10
Points to a \fBt_optmgmt\fR structure. See also \fIret\fR argument.
.IP \fIret\fR 10
Points to a \fBt_optmgmt\fR structure containing the following members:
.EX
struct netbuf \fIopt\fP;
long \fIflags\fR;
.EE
.IP 
The meanings of the fields are as follows:
.RS 10
.IP  \fIopt\fP 
Identifies protocol options.
.IP \fIflags\fP	
Specifies the action to take with these options.
.RE
.PP
The options are represented by a \fBnetbuf\fR structure in a manner
similar to the address in 
.PN t_bind(). 
The \fIreq\fR argument is
used to request a specific action of the provider and to send options
to the provider. The \fIlen\fR field specifies the number of bytes in the
options. The \fIbuf\fR field points to the options buffer, and the
\fImaxlen\fR field has no meaning for the \fIreq\fR argument. The
transport provider can return options and flag values to the user
through \fIret\fR. For \fIret\fR, \fImaxlen\fR specifies the maximum
size of the options buffer,  and \fIbuf\fR points to the buffer where the
options are to be placed. On return, \fIlen\fR specifies the number of
bytes of options returned. The \fImaxlen\fR field has no meaning for
the \fIreq\fR argument, but must be set in the \fIret\fR argument to
specify the maximum number of bytes the option buffer can hold. The
actual structure and content of the options is imposed by the transport
provider.
.PP
The \fIflags\fR field of \fIreq\fR must specify one of the following
actions:
.RS 10
.IP "T_NEGOTIATE" 16
This action enables the user to negotiate the values of the options specified 
in \fIreq\fP with the transport provider. The transport provider evaluates the 
requested options and negotiates the values, returns the negotiated values 
through \fIret\fP.
.sp
.IP "T_CHECK" 16
This action enables the user to verify whether the options specified in \fIreq\fP 
are supported by the transport provider. On return, the \fIflags\fP field of \fIret\fR 
has either T_SUCCESS or T_FAILURE set to indicate to the user 
whether options are supported. These \fIflags\fR are only meaningful for the 
T_CHECK request.
.IP "T_DEFAULT" 16
This action enables a user to retrieve the default options supported by the transport 
provider into the \fIopt\fP field of \fIret\fP. In \fIreq\fR, the \fIlen\fP field of 
\fIopt\fP must be zero and the \fIbuf\fP field may be NULL.
.RE
.SH Description
The 
.PN t_optmgmt()
function enables a transport user to receive,
verify, or negotiate protocol options with the transport provider.
.NXR "t_optmgmt system call"
.NXR "transport user" "protocol options"
.PP
If issued as part of the connectionless-mode service,
.PN t_optmgmt()
may block due to flow control constraints. That is, the function does not complete until the 
transport provider has processed all previously sent data units.
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 6p
Parameters@Before Call@After Call
.sp 6p
_
.sp 6p
fd@x@/
req->opt.maxlen@/@/
req->opt.len@x@/
req->opt.buf@x(x)@/
req->flags@x@/
ret->opt.maxlen@x@/
ret->opt.len@/@x
ret->opt.buf@x@(x)
ret->flags@/@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.
.TP 20
[TACCES]
The user does not have permission to negotiate the specified options.
.TP 20
[TBADOPT]
The specified protocol options were in an incorrect format or contained
illegal information.
.TP 20
[TBADFLAG]
An invalid flag was specified.
.TP 20
[TBUFOVFLW]
The number of bytes allowed for an incoming argument is not sufficient
to store the value of that argument. The information to be returned in
\fIret\fR is discarded.
.TP 20
[TNOTSUPPORT]
This function is not supported by the current implementation of XTI.
.TP 20
[TSYSERR]
A system error has occurred during execution of this function.
.SH See Also
.MS t_accept 3xti , 
.MS t_alloc 3xti ,
.MS t_connect 3xti ,
.MS t_getinfo 3xti , 
.MS t_listen 3xti , 
.MS t_open 3xti ,
.MS t_rcvconnect 3xti