NAME
t_getinfo() — get protocol-specific service information
SYNOPSIS
#include <xti.h> /* for X/OPEN Transport Interface - XTI */
/* or */
#include <tiuser.h> /* for Transport Layer Interface - TLI */
int t_getinfo (fd, info);
int fd;
struct info *info;
DESCRIPTION
The
t_getinfo()
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
t_open().
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:
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
t_connect()
and
t_rcvconnect().
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 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()
and
t_rcvdis()
functions.
A value of -1 specifies that there is no limit on the amount of data sent
with
these abortive release functions.
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
T_SENDZERO
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
CAE Specification X/Open Transport Interface (XTI)
manual for a discussion of the
separate issue of zero-length fragments within a TSDU. Note: HP currently
does not support
T_SENDZERO
flag within the
timod
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
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 of the underlying transport protocol.
The
servtype
field of
info
specifies 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()
will return -2 for
etsdu,
connect,
and
discon.
Valid States
All - apart from
T_UNINIT.
Fork Safety
t_getinfo
is not fork-safe.
RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned, and
t_errno
is set to indicate the error.
ERRORS
On failure,
t_errno
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 transport provider for which there is no
suitable XTI (t_errno).
STANDARDS CONFORMANCE
t_getinfo(): SVID2, XPG3, XPG4
Printable version
