NAME

t_look() − look at the current event on a transport endpoint

SYNOPSIS

#include <xti.h> (for X/OPEN Transport Interface - XTI)

or

#include <tiuser.h> (for Transport Layer Interface - TLI)

int t_look (fd)
int fd;

DESCRIPTION

The t_look() 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. 

Valid States

All - apart from T_UNINIT

XTI Internet Protocol-specific Information

As soon as a segment with the TCP urgent pointer set enters the TCP receive buffer, the event T_EXDATA is indicated.  T_EXDATA remains set until all data up to the byte pointed to by the TCP urgent pointer has been received.  If the urgent pointer is updated, and the user has not yet received the byte previously pointed to by the urgent pointer, the update is transparent to the user. 

RETURN VALUE

Upon success, t_look() returns a value that indicates which of the following 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_ERROR (TLI ONLY) fatal error occurred. 

­T_EXDATA expedited data received. 

­T_DISCONNECT disconnect received. 

­T_UDERR datagram error indication. 

­T_ORDREL orderly release indication. 

­T_GODATA (XTI only) flow control restrictions on normal data flow have been lifted.  Normal data may be sent again. 

­T_GOEXDATA (XTI only) flow control restrictions on expedited data flow have been lifted.  Expedited data may be sent again. 

ERRORS

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

­[TBADF] The specified identifier does not refer to a transport endpoint. 

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

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

SEE ALSO

t_open(3), t_snd(3), t_sndudata(3). 

STANDARDS CONFORMANCE

t_look(): SVID2, XPG3, XPG4

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996