Purpose
Gets protocol-specific service information.
Library
Transport Layer Interface Library (libtli.a)
Syntax
#include <tiuser.h>
int t_getinfo(fd, info)
int fd;
struct t_info * info;
Description
The t_getinfo subroutine returns the
current characteristics of the underlying transport protocol associated
with fd file descriptor. The t_info structure
is used to return the same information returned by the t_open subroutine.
This function enables a transport user to access this information
during any phase of communication.
Parameters
| Item |
Description |
|---|
| fd |
Specifies the file descriptor. |
| info |
Points to a t_info structure that contains the following
members:
long addr;
long options;
long tsdu;
long etsdu;
long connect;
long discon;
long servtype;
The values of the fields have the following
meanings:
- addr
- A value greater than or equal to 0 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.
- options
- A value greater than or equal to 0 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.
- tsdu
- A value greater than 0 specifies the maximum size of a transport
service data unit (TSDU); a value of 0 specifies that the transport
provider does not support the concept of TSDU, although it does support
the sending of a data stream having 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.
- etsdu
- A value greater than 0 specifies the maximum size of an expedited
transport service data unit (ETSDU); a value of 0 specifies that the
transport provider does not support the concept of ETSDU, although
it does support the sending of an expedited data stream having no
logical boundaries preserved across a connection; a value of -1 specifies
that there is no limit on the size of an ETSDU; and a value of -2
specifies that the transfer of expedited data is not supported by
the transport provider.
- connect
- A value greater than or equal to 0 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.
- discon
- A value greater than or equal to 0 specifies the maximum amount
of data that may be associated with the t_snddis and t_rcvdis subroutines;
a value of -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.
- servtype
- This field specifies the service type supported by the transport
provider.
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 t_alloc subroutine
may be used to allocate these buffers. An error will result if a transport
user exceeds the allowed data size on any function. The value of each
field can change as a result of option negotiation; the t_getinfo subroutine
enables a user to retrieve the current characteristics.
|
Return Values
On successful completion, the t_getinfo subroutine
returns a value of 0. Otherwise, it returns a value of -1, and the t_errno variable
is set to indicate the error.
The servtype field of the info parameter
may specify one of the following values on return:
| Value |
Description |
|---|
| T_COTS |
The transport provider supports a connection-mode service,
but does not support the optional orderly release facility. |
| T_COTS_ORD |
The transport provider supports a connection-mode service
with the optional orderly release facility. |
| T_CLTS |
The transport provider supports a connectionless-mode service.
For this service type, the t_open subroutine returns -2 for
the values in the etsdu, connect, and discon fields. |
Error Codes
In unsuccessful, the t_errno variable
is set to one of the following:
| Value |
Description |
|---|
| TBADF |
The specified file descriptor does not refer to a transport
end point. |
| TSYSERR |
A system error has occurred during execution of this function. |