t_getinfo(3N) manual page
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t_getinfo - get protocol-specific service information
cc [
flag ... ] file ... -lnsl [ library ... ]
#include <tiuser.h>
int t_getinfo(int fildes,
struct t_info *info);
MT-Safe
This function returns
the current characteristics of the underlying transport protocol associated
with file descriptor fildes. The info structure is used to return the same
information returned by t_open(3N)
. This function enables a transport user
to access this information during any phase of communication.
The info argument
points to a t_info structure, which contains the following members:
- long
addr;
- /* max size of transport protocol address */
- long options;
- /* max
number of bytes of protocol-specific options */
- long tsdu;
- /* max size of
transport service data unit (TSDU
) */
- long etsdu;
- /* max size of expedited
transport service data unit (ETSDU
) */
- long connect;
- /* max amount of data
allowed on connection establishment functions */
- long discon;
- /* max amount
of data allowed on t_snddis(3N)
and t_rcvdis(3N)
functions */
- long servtype;
- /* service type supported by the transport provider */
The values of the
fields have the following meanings:
- addr
- 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.
- options
- 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.
- tsdu
- 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 across a connection of a data stream
with no logical boundaries preserved; 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 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 does
support the sending across a connection of an expedited data stream with
no logical boundaries preserved. 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 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.
- discon
- A value greater than or equal to zero specifies the maximum amount
of data that may be associated with the t_snddis(3N)
and t_rcvdis(3N)
functions; 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, as described below.
If a transport user is concerned
with protocol independence, the above sizes may be accessed to determine
how large the buffers must be to hold each piece of information. Alternatively,
the t_alloc() function 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 may change as a result of option negotiation, and
t_getinfo() enables a user to retrieve the current characteristics.
The
servtype field of info may specify one of the following values on return:
- 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, t_open(3N)
will return -2 for etsdu, connect, and
discon.
t_getinfo() returns 0 on success. On failure t_getinfo()
returns -1, t_errno is set to indicate the error, and possibly errno is
set.
On failure, t_errno will be set to one of the following:
- TBADF
-
The specified file descriptor does not refer to a transport endpoint.
- TSYSERR
- A system error has occurred during execution of this function, errno will
be set to the specific error.
t_open(3N)
, t_rcvdis(3N)
, t_snddis(3N)
This interface is safe in multithreaded applications.
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