t_getinfo(3N) UNIX System V(Networking Support Utilities) t_getinfo(3N)
NAME
tgetinfo - get protocol-specific service information
SYNOPSIS
#include <tiuser.h>
int tgetinfo(fd, info)
int fd;
struct tinfo *info;
DESCRIPTION
This function returns the current characteristics of the underlying
transport protocol associated with file descriptor fd. The info
structure is used to return the same information returned by topen.
This function enables a transport user to access this information during
any phase of communication.
This argument points to a tinfo structure, which contains the following
members:
long addr;/* max size of the transport protocol address */
long options;/* max number of bytes of protocol-specific options */
long tsdu;/* max size of a transport service data unit (TSDU) */
long etsdu;/* max size of an 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 tsnddis and trcvdis 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 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.
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t_getinfo(3N) UNIX System V(Networking Support Utilities) t_getinfo(3N)
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
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 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 tsnddis and
trcvdis 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 talloc 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 tgetinfo enables a
user to retrieve the current characteristics.
The servtype field of info may specify one of the following values on
return:
TCOTS The transport provider supports a connection-mode service
but does not support the optional orderly release
facility.
TCOTSORD The transport provider supports a connection-mode service
with the optional orderly release facility.
TCLTS The transport provider supports a connectionless-mode
service. For this service type, topen will return -2 for
etsdu, connect, and discon.
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t_getinfo(3N) UNIX System V(Networking Support Utilities) t_getinfo(3N)
On failure, terrno may 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.
SEE ALSO
topen(3N)
Programmer's Guide: Networking Interfaces
DIAGNOSTICS
tgetinfo returns 0 on success and -1 on failure and terrno is set to
indicate the error.
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