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:

Error Description Values

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

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

dup(2), exec(2), fork(2), open(2), attributes(5)