t_getinfo(3)t_getinfo(3)NAMEt_getinfo() - get protocol-specific service information
SYNOPSISDESCRIPTION
The function returns the current characteristics of the underlying
transport protocol associated with file descriptor fd. The info struc‐
ture is used to return the same information returned by This function
enables a transport user to access this information during any phase of
communication.
This argument points to a structure which contains the following mem‐
bers:
t_scalar_t addr; /* max size of the transport protocol address */
t_scalar_t options; /* max number of bytes of protocol-specific options */
t_scalar_t tsdu; /* max size of a transport service data unit,TSDU */
t_scalar_t etsdu; /* max size of expedited transport service data unit,ETSDU */
t_scalar_t connect; /* max data allowed on connection establishment functions */
t_scalar_t discon; /* max data allowed on t_snddis and t_rcvdis functions */
t_scalar_t servtype; /* service type supported by the transport provider */
t_scalar_t flags; /* other info about 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.
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.
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.
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.
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 the
connection establishment functions and
A value of −1 specifies that there is no limit on the
amount of data sent during connection establishment.
A value of −2 specifies that the transport provider
does not allow data to be sent with connection estab‐
lishment functions.
discon A value greater than or equal to zero specifies the
maximum amount of data that may be associated with the
and functions.
A value of −1 specifies that there is no limit on the
amount of data sent with these abortive release func‐
tions.
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.
flags This is a bit field used to specify other information
about the transport provider. If the bit is set in
flags, this indicates that the underlying transport
provider supports the sending of zero-length TSDUs.
See Appendix A, "ISO Transport Protocol Information"
of the manual for a discussion of the separate issue
of zero-length fragments within a TSDU. Note: HP cur‐
rently does not support flag within the module.
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 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 enables a user
to retrieve the current characteristics of the underlying transport
protocol.
The servtype field of info specifies one of the following values on
return:
The transport provider supports a connection-mode service but does not
support
the optional orderly release facility.
The transport provider supports a connection-mode service with the
optional
orderly release facility.
The transport provider supports a connectionless-mode service. For
this
service type, will return −2 for etsdu, connect, and
discon.
Valid States
All - apart from
Fork Safety
is not fork-safe.
RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a
value of −1 is returned, and is set to indicate the error.
ERRORS
On failure, is set to the following
[TBADF] The specified identifier does not refer to a transport
endpoint.
[TSYSERR] A system error has occurred during execution of this
function.
[TPROTO] (XTI only) This error indicates that a communication
problem has been detected between XTI and the trans‐
port provider for which there is no suitable XTI (
SEE ALSOt_alloc(3), t_open(3), thread_safety(5).
STANDARDS CONFORMANCEt_getinfo(3)
