t_look(3N)

NAME

t_look − look at the current event on a transport endpoint

SYNOPSIS

cc [ flag ... ] file ... −lnsl [ library ... ]

#include <xti.h>

int t_look(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, a different header file, tiuser.h , must be used. Refer to the section, TLI COMPATIBILITY , for a description of differences between the two interfaces.

This function returns the current event that is awaiting acknowledgement and that originated 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. Those events that require immediate notification of the user are indicated by the error value TLOOK on the current or next function to be executed. Such events block the progress of communications until acknowledgement is given.

Details on events which cause functions to produce the failure indication TLOOK may be found in Section 5.6 of X/Open CAE Specification: Networking Services, Issue 4.

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

VALID STATES

Legitimate states (see t_getstate(3N)) for a call to this routine are every one except T_UNINIT .

RETURN VALUES

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

T_CONNECT Connect confirmation received

T_DATA Normal data received

T_DISCONNECT Disconnect received

T_EXDATA Expedited data received

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.

T_LISTEN Connection indication received

T_ORDREL Orderly release indication

T_UDERR Datagram error indication

On failure, −1 is returned, t_errno is set to indicate the error, and possibly errno is set.

ERRORS

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 t_errno value.

TSYSERR A system error has occurred during execution of this function, errno will be set to the specific error.

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>

Return Values

The return values that are defined by the XTI interface and cannot be returned by the TLI interface are:

T_GODATA

T_GOEXDATA

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

For more information refer to the Transport Interfaces Programming Guide.

ATTRIBUTES

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

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	MT-Safe

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