NAME

t_sync - synchronise transport library

SYNOPSIS

#include <xti.h>

int t_sync(
    int fd)

DESCRIPTION

Parameters
Before call
After call
fd
x
/

For the transport endpoint specified by fd, t_sync() synchronises the data structures managed by the transport library with information from the underlying transport provider. In doing so, it can convert an uninitialised file descriptor (obtained via open(), dup() or as a result of a fork() and exec()) to an initialised 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 synchronise their interaction with a transport provider.

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

VALID STATES

ALL - apart from T_UNINIT

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.

RETURN VALUE

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).

SEE ALSO

dup(), exec(), fork(), open().