TGETINFO(3N) DG/UX 4.30 TGETINFO(3N)
NAME
t_getinfo - 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 t_info 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 TSDU (ETSDU) */
long connect; /* max amount of data allowed on connection functions */
long discon; /* max amount of data allowed on t_snddis and t_rcvdis */
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
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TGETINFO(3N) DG/UX 4.30 TGETINFO(3N)
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 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:
T_COTS The transport provider supports a connection-
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TGETINFO(3N) DG/UX 4.30 TGETINFO(3N)
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, topen will return -2 for etsdu, connect,
and discon.
On failure, t_errno 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
t_open(3N).
DIAGNOSTICS
tgetinfo returns 0 on success and -1 on failure and t_errno
is set to indicate the error.
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