t_getinfo.3xti

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH t_getinfo 3xti
.SH Name
t_getinfo \- get protocol-specific service information 
.SH Syntax
.B #include <xti.h>
.br
.sp 1
.B int t_getinfo(\fIfd, info\fB)
.br
.B int \fIfd\fB;
.br
.B struct t_info \fI*info\fB;
.SH Arguments
.IP \fIfd\fR 10
Identifies the file descriptor that is associated with the underlying 
transport protocol from which the current characteristics are to be returned.
.IP \fIinfo\fR 10
Specifies the structure that is used to return the same information
returned by 
.PN t_open()\fR.\fR 
Points to a \fBt_info\fR structure which contains the following members:
.RS
.IP "long \fIaddr\fP;" 15
/* max size of the transport protocol address */
.IP "long \fIoptions\fP;" 15
/* max number of bytes of protocol-specific options */
.IP "long \fItsdu\fP;" 15
/* max size of a transport service data unit (TSDU) */
.IP "long \fIetsdu\fP;" 15
/* max size of an expedited transport service data unit (ETSDU) */
.IP "long \fIconnect\fP;" 15
/* max amount of data allowed on connection establishment functions */
.IP "long \fIdiscon\fP;" 15
/* max amount of data allowed on 
.PN t_snddis()
and 
.PN t_rcvdis()
functions */
.IP "long \fIservtype\fP;" 15
/* service type supported by the transport provider */
.RE
.IP 
The values of the fields have the following meanings:
.RS 10
.IP \fIaddr\fP 12
A value greater than or equal to zero indicates the maximum size of a transport protocol address; 
a value of \-1 specifies that there is no limit on the address size; and a value of \-2 specifies that
the transport provider does not provide user access to transport protocol addresses.
.IP \fIoptions\fP 12
A value greater than or equal to zero indicates the maximum number of bytes of protocol-specific 
options supported by the provider; a value of \-1 specifies that there is no limit on the option 
size and a value of \-2 specifies that the transport provider does not support user-settable options.
.IP \fItsdu\fP 12
A value greater than zero specifies the maximum size of a transport service data unit (TSDU); a 
value of zero specifies that the transport provider does not support the concept of TSDU, although 
it does support the sending of a data stream with no logical boundaries preserved across a 
connection; a value of \-1 specifies that there is no limit on the size of a TSDU and a value of \-2 
specifies that the transfer of normal data is not supported by the transport provider.
.IP \fIetsdu\fP 12
A value greater than zero specifies the maximum size of an expedited transport service data unit 
(ETSDU); a value of zero specifies that the transport provider does not support the concept of 
ETSDU, although it it does support the sending of an expedited data stream with no logical 
boundaries preserved across a connection; a value of \-1 specifies that there is no limit on the 
size of ETSDU; and a value of \-2 specifies that the transfer of expedited data is not supported 
by the transport provider.
.IP \fIconnect\fP 12
A value greater than or equal to zero specifies the maximum amount of data that may be associated 
with connection establishment functions; a value of \-1 specifies that there is no limit on the 
amount of data sent during connection establishment; and a value of \-2 specifies that the transport 
provider does not allow data to be sent with connection establishment functions.
.IP \fIdiscon\fP 12
A value greater than or equal to zero specifies the maximum amount of data that may be associated 
with the 
.PN t_snddis()
and 
.PN t_rcvdis()
functions; a value \-1 specifies that there 
is no limit on the amount of data sent with these abortive release functions; and a value of \-2 
specifies that the transport provider does not allow data to be sent with the abortive release 
functions.
.IP \fIservtype\fP 12
This field specifies the service type supported by the transport provider, as described.
.RE
.IP
.sp 2
If a transport user is concerned with protocol independence, the sizes may be accessed
to determine how large the buffers must be to hold each piece of information. Alternatively, 
the 
.PN t_alloc()
function can be used to allocate these buffers. An error results if a transport user 
exceeds the allowed data size on any function. The value of each field may change as a result 
of option negotiation, and 
.PN t_getinfo() 
enables a user to retrieve the current characteristics of the underlying transport protocol.
.IP
The \fIservtype\fR field of \fIinfo\fR specifies one of the following values on return:
.RS 10
.IP T_COTS 12
The transport provider supports a connection-mode service but does not support the optional orderly 
release facility.
.IP T_COTS_ORD 12 
The transport provider supports a connection-mode service with the optional orderly release facility.
.IP T_CLTS	 12
The transport provider supports a connectionless-mode service. For this service type, 
.PN t_open()
returns \-2 for ETSDU, 
.PN connect
and 
.PN discon\fR.\fR
.RE
.SH Description
This function returns the current characteristics of the underlying
transport protocol associated with file descriptor \fIfd\fR. The
\fIinfo\fR structure is used to return the same information returned by
.PN t_open()\fR.\fR 
This function enables a transport user to access
this information during any phase of communications.
.NXR "transport protocol" "returning characteristics"
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 4p
Parameters@Before Call@After Call
.sp 4p
_
.sp 6p
fd@x@/
info->addr@/@x
info->options@/@x
info->tsdu@/@x
info->etsdu@/@x
info->connect@/@x
info->discon@/@x
info->sertype@/@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
[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
t_alloc(3xti), 
t_open(3xti)