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.

This function returns the current event on the transport endpoint specified by fd. This function enables a transport provider to notify a transport user of an asynchronous event when the user is calling functions in synchronous mode. Certain events require immediate notification of the user and are indicated by a specific error, TLOOK, on the current or next function to be executed.

This function also enables a transport user to poll a transport endpoint periodically for asynchronous events.

Upon success, t_look() returns a value that indicates which of the allowable events has occurred, or returns zero if no event exists. One of the following events is returned:

T_LISTEN

Connection indication received.

T_CONNECT

Connect confirmation received.

T_DATA

Normal data received.

T_EXDATA

Expedited data received.

T_DISCONNECT

Disconnection received.

T_UDERR

Datagram error indication.

T_ORDREL

Orderly release indication.

T_GODATA

Flow control restrictions on normal data flow that led to a TFLOW error have been lifted. Normal data may be sent again.

T_GOEXDATA

Flow control restrictions on expedited data flow that led to a TFLOW error have been lifted. Expedited data may be sent again.

On failure, -1 is returned and t_errno is set to indicate the error.

ALL - apart from T_UNINIT.

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

TBADF

The specified file descriptor does not refer to a transport endpoint.

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).

TSYSERR

A system error has occurred during execution of this function.

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

Return Values

Error Description Values

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

t_open(3NSL), t_snd(3NSL), t_sndudata(3NSL), attributes(5)