T_SYNC(3NSL) Networking Services Library Functions T_SYNC(3NSL)


NAME


t_sync - synchronize transport library

SYNOPSIS


#include <xti.h>


int t_sync(int fd);


DESCRIPTION


This routine is part of the XTI interfaces which evolved from the TLI
interfaces. XTI represents the future evolution of these interfaces.
However, TLI interfaces are supported for compatibility. When using a TLI
routine that has the same name as an XTI routine, the tiuser.h header
file must be used. Refer to the TLI COMPATIBILITY section for a
description of differences between the two interfaces.


For the transport endpoint specified by fd, t_sync() synchronizes the
data structures managed by the transport library with information from
the underlying transport provider. In doing so, it can convert an
uninitialized file descriptor (obtained by means of a open(2), dup(2) or
as a result of a fork(2) and exec(2)) to an initialized transport
endpoint, assuming that the file descriptor referenced a transport
endpoint, by updating and allocating the necessary library data
structures. This function also allows two cooperating processes to
synchronize their interaction with a transport provider.


For example, if a process forks a new process and issues an exec(2), the
new process must issue a t_sync() to build the private library data
structure associated with a transport endpoint and to synchronize the
data structure with the relevant provider information.


It is important to remember that the transport provider treats all users
of a transport endpoint as a single user. If multiple processes are using
the same endpoint, they should coordinate their activities so as not to
violate the state of the transport endpoint. The function t_sync()
returns the current state of the transport endpoint to the user, thereby
enabling the user to verify the state before taking further action. This
coordination is only valid among cooperating processes; it is possible
that a process or an incoming event could change the endpoint's state
after a t_sync() is issued.


If the transport endpoint is undergoing a state transition when t_sync()
is called, the function will fail.

RETURN VALUES


On successful completion, the state of the transport endpoint is
returned. Otherwise, a value of -1 is returned and t_errno is set to
indicate an error. The state returned is one of the following:

T_UNBND
Unbound.


T_IDLE
Idle.


T_OUTCON
Outgoing connection pending.


T_INCON
Incoming connection pending.


T_DATAXFER
Data transfer.


T_OUTREL
Outgoing orderly release (waiting for an orderly release
indication).


T_INREL
Incoming orderly release (waiting for an orderly release
request).


ERRORS


On failure, t_errno is set to one of the following:

TBADF
The specified file descriptor does not refer to a transport
endpoint. This error may be returned when the fd has been
previously closed or an erroneous number may have been
passed to the call.


TPROTO
This error indicates that a communication problem has been
detected between XTI and the transport provider for which
there is no other suitable XTI error (t_errno).


TSTATECHNG
The transport endpoint is undergoing a state change.


TSYSERR
A system error has occurred during execution of this
function.


TLI COMPATIBILITY


The XTI and TLI interface definitions have common names but use different
header files. This, and other semantic differences between the two
interfaces are described in the subsections below.

Interface Header


The XTI interfaces use the header file, xti.h. TLI interfaces should not
use this header. They should use the header:
#include <tiuser.h>

Error Description Values


The t_errno value that can be set by the XTI interface and cannot be set
by the TLI interface is:
TPROTO

ATTRIBUTES


See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT Level | Safe |
+---------------+-----------------+

SEE ALSO


dup(2), exec(2), fork(2), open(2), attributes(7)


May 7, 1998 T_SYNC(3NSL)